Commit Graph

318 Commits

Author SHA1 Message Date
Andy Lutomirski
9999c8c01f x86/entry: Call enter_from_user_mode() with IRQs off
Now that slow-path syscalls always enter C before enabling
interrupts, it's straightforward to call enter_from_user_mode() before
enabling interrupts rather than doing it as part of entry tracing.

With this change, we should finally be able to retire exception_enter().

This will also enable optimizations based on knowing that we never
change context tracking state with interrupts on.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/bc376ecf87921a495e874ff98139b1ca2f5c5dd7.1457558566.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-03-10 10:53:26 +01:00
Andy Lutomirski
a798f09111 x86/entry/32: Change INT80 to be an interrupt gate
We want all of the syscall entries to run with interrupts off so that
we can efficiently run context tracking before enabling interrupts.

This will regress int $0x80 performance on 32-bit kernels by a
couple of cycles.  This shouldn't matter much -- int $0x80 is not a
fast path.

This effectively reverts:

  657c1eea00 ("x86/entry/32: Fix entry_INT80_32() to expect interrupts to be on")

... and fixes the same issue differently.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/59b4f90c9ebfccd8c937305dbbbca680bc74b905.1457558566.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-03-10 10:53:26 +01:00
Andy Lutomirski
fda57b2267 x86/entry: Improve system call entry comments
Ingo suggested that the comments should explain when the various
entries are used.  This adds these explanations and improves other
parts of the comments.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/9524ecef7a295347294300045d08354d6a57c6e7.1457578375.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-03-10 09:48:15 +01:00
Andy Lutomirski
392a62549f x86/entry: Remove TIF_SINGLESTEP entry work
Now that SYSENTER with TF set puts X86_EFLAGS_TF directly into
regs->flags, we don't need a TIF_SINGLESTEP fixup in the syscall
entry code.  Remove it.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/2d15f24da52dafc9d2f0b8d76f55544f4779c517.1457578375.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-03-10 09:48:14 +01:00
Andy Lutomirski
7536656f08 x86/entry/32: Simplify and fix up the SYSENTER stack #DB/NMI fixup
Right after SYSENTER, we can get a #DB or NMI.  On x86_32, there's no IST,
so the exception handler is invoked on the temporary SYSENTER stack.

Because the SYSENTER stack is very small, we have a fixup to switch
off the stack quickly when this happens.  The old fixup had several issues:

 1. It checked the interrupt frame's CS and EIP.  This wasn't
    obviously correct on Xen or if vm86 mode was in use [1].

 2. In the NMI handler, it did some frightening digging into the
    stack frame.  I'm not convinced this digging was correct.

 3. The fixup didn't switch stacks and then switch back.  Instead, it
    synthesized a brand new stack frame that would redirect the IRET
    back to the SYSENTER code.  That frame was highly questionable.
    For one thing, if NMI nested inside #DB, we would effectively
    abort the #DB prologue, which was probably safe but was
    frightening.  For another, the code used PUSHFL to write the
    FLAGS portion of the frame, which was simply bogus -- by the time
    PUSHFL was called, at least TF, NT, VM, and all of the arithmetic
    flags were clobbered.

Simplify this considerably.  Instead of looking at the saved frame
to see where we came from, check the hardware ESP register against
the SYSENTER stack directly.  Malicious user code cannot spoof the
kernel ESP register, and by moving the check after SAVE_ALL, we can
use normal PER_CPU accesses to find all the relevant addresses.

With this patch applied, the improved syscall_nt_32 test finally
passes on 32-bit kernels.

[1] It isn't obviously correct, but it is nonetheless safe from vm86
    shenanigans as far as I can tell.  A user can't point EIP at
    entry_SYSENTER_32 while in vm86 mode because entry_SYSENTER_32,
    like all kernel addresses, is greater than 0xffff and would thus
    violate the CS segment limit.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/b2cdbc037031c07ecf2c40a96069318aec0e7971.1457578375.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-03-10 09:48:14 +01:00
Andy Lutomirski
f2b375756c x86/entry: Vastly simplify SYSENTER TF (single-step) handling
Due to a blatant design error, SYSENTER doesn't clear TF (single-step).

As a result, if a user does SYSENTER with TF set, we will single-step
through the kernel until something clears TF.  There is absolutely
nothing we can do to prevent this short of turning off SYSENTER [1].

Simplify the handling considerably with two changes:

  1. We already sanitize EFLAGS in SYSENTER to clear NT and AC.  We can
     add TF to that list of flags to sanitize with no overhead whatsoever.

  2. Teach do_debug() to ignore single-step traps in the SYSENTER prologue.

That's all we need to do.

Don't get too excited -- our handling is still buggy on 32-bit
kernels.  There's nothing wrong with the SYSENTER code itself, but
the #DB prologue has a clever fixup for traps on the very first
instruction of entry_SYSENTER_32, and the fixup doesn't work quite
correctly.  The next two patches will fix that.

[1] We could probably prevent it by forcing BTF on at all times and
    making sure we clear TF before any branches in the SYSENTER
    code.  Needless to say, this is a bad idea.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/a30d2ea06fe4b621fe6a9ef911b02c0f38feb6f2.1457578375.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-03-10 09:48:13 +01:00
Andy Lutomirski
c2c9b52fab x86/entry/32: Restore FLAGS on SYSEXIT
We weren't restoring FLAGS at all on SYSEXIT.  Apparently no one cared.

With this patch applied, native kernels should always honor
task_pt_regs()->flags, which opens the door for some sys_iopl()
cleanups.  I'll do those as a separate series, though, since getting
it right will involve tweaking some paravirt ops.

( The short version is that, before this patch, sys_iopl(), invoked via
  SYSENTER, wasn't guaranteed to ever transfer the updated
  regs->flags, so sys_iopl() had to change the hardware flags register
  as well. )

Reported-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/3f98b207472dc9784838eb5ca2b89dcc845ce269.1457578375.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-03-10 09:48:12 +01:00
Andy Lutomirski
67f590e8d4 x86/entry/32: Filter NT and speed up AC filtering in SYSENTER
This makes the 32-bit code work just like the 64-bit code.  It should
speed up syscalls on 32-bit kernels on Skylake by something like 20
cycles (by analogy to the 64-bit compat case).

It also cleans up NT just like we do for the 64-bit case.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/07daef3d44bd1ed62a2c866e143e8df64edb40ee.1457578375.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-03-10 09:48:12 +01:00
Andy Lutomirski
e786041153 x86/entry/compat: In SYSENTER, sink AC clearing below the existing FLAGS test
CLAC is slow, and the SYSENTER code already has an unlikely path
that runs if unusual flags are set.  Drop the CLAC and instead rely
on the unlikely path to clear AC.

This seems to save ~24 cycles on my Skylake laptop.  (Hey, Intel,
make this faster please!)

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/90d6db2189f9add83bc7bddd75a0c19ebbd676b2.1457578375.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-03-10 09:48:12 +01:00
Andy Lutomirski
58a5aac533 x86/entry/32: Introduce and use X86_BUG_ESPFIX instead of paravirt_enabled
x86_64 has very clean espfix handling on paravirt: espfix64 is set
up in native_iret, so paravirt systems that override iret bypass
espfix64 automatically.  This is robust and straightforward.

x86_32 is messier.  espfix is set up before the IRET paravirt patch
point, so it can't be directly conditionalized on whether we use
native_iret.  We also can't easily move it into native_iret without
regressing performance due to a bizarre consideration.  Specifically,
on 64-bit kernels, the logic is:

  if (regs->ss & 0x4)
          setup_espfix;

On 32-bit kernels, the logic is:

  if ((regs->ss & 0x4) && (regs->cs & 0x3) == 3 &&
      (regs->flags & X86_EFLAGS_VM) == 0)
          setup_espfix;

The performance of setup_espfix itself is essentially irrelevant, but
the comparison happens on every IRET so its performance matters.  On
x86_64, there's no need for any registers except flags to implement
the comparison, so we fold the whole thing into native_iret.  On
x86_32, we don't do that because we need a free register to
implement the comparison efficiently.  We therefore do espfix setup
before restoring registers on x86_32.

This patch gets rid of the explicit paravirt_enabled check by
introducing X86_BUG_ESPFIX on 32-bit systems and using an ALTERNATIVE
to skip espfix on paravirt systems where iret != native_iret.  This is
also messy, but it's at least in line with other things we do.

This improves espfix performance by removing a branch, but no one
cares.  More importantly, it removes a paravirt_enabled user, which is
good because paravirt_enabled is ill-defined and is going away.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Borislav Petkov <bp@suse.de>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luis R. Rodriguez <mcgrof@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: boris.ostrovsky@oracle.com
Cc: david.vrabel@citrix.com
Cc: konrad.wilk@oracle.com
Cc: lguest@lists.ozlabs.org
Cc: xen-devel@lists.xensource.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-03-08 14:16:44 +01:00
Ingo Molnar
ec87e1cf7d Linux 4.5-rc7
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Merge tag 'v4.5-rc7' into x86/asm, to pick up SMAP fix

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-03-07 09:27:30 +01:00
Christoph Hellwig
4babf2c5ef x86: wire up preadv2 and pwritev2
Signed-off-by: Milosz Tanski <milosz@adfin.com>
[hch: rebased due to newly added syscalls]
Reviewed-by: Stephen Bates <stephen.bates@pmcs.com>
Tested-by: Stephen Bates <stephen.bates@pmcs.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-03-04 12:20:10 -05:00
Josh Poimboeuf
c0dd671686 objtool: Mark non-standard object files and directories
Code which runs outside the kernel's normal mode of operation often does
unusual things which can cause a static analysis tool like objtool to
emit false positive warnings:

 - boot image
 - vdso image
 - relocation
 - realmode
 - efi
 - head
 - purgatory
 - modpost

Set OBJECT_FILES_NON_STANDARD for their related files and directories,
which will tell objtool to skip checking them.  It's ok to skip them
because they don't affect runtime stack traces.

Also skip the following code which does the right thing with respect to
frame pointers, but is too "special" to be validated by a tool:

 - entry
 - mcount

Also skip the test_nx module because it modifies its exception handling
table at runtime, which objtool can't understand.  Fortunately it's
just a test module so it doesn't matter much.

Currently objtool is the only user of OBJECT_FILES_NON_STANDARD, but it
might eventually be useful for other tools.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Bernd Petrovitsch <bernd@petrovitsch.priv.at>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Chris J Arges <chris.j.arges@canonical.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michal Marek <mmarek@suse.cz>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Pedro Alves <palves@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: live-patching@vger.kernel.org
Link: http://lkml.kernel.org/r/366c080e3844e8a5b6a0327dc7e8c2b90ca3baeb.1456719558.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-02-29 08:35:02 +01:00
Andy Lutomirski
3d44d51bd3 x86/entry/compat: Add missing CLAC to entry_INT80_32
This doesn't seem to fix a regression -- I don't think the CLAC was
ever there.

I double-checked in a debugger: entries through the int80 gate do
not automatically clear AC.

Stable maintainers: I can provide a backport to 4.3 and earlier if
needed.  This needs to be backported all the way to 3.10.

Reported-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: <stable@vger.kernel.org> # v3.10 and later
Fixes: 63bcff2a30 ("x86, smap: Add STAC and CLAC instructions to control user space access")
Link: http://lkml.kernel.org/r/b02b7e71ae54074be01fc171cbd4b72517055c0e.1456345086.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-02-25 08:31:20 +01:00
Adam Buchbinder
6a6256f9e0 x86: Fix misspellings in comments
Signed-off-by: Adam Buchbinder <adam.buchbinder@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: trivial@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-02-24 08:44:58 +01:00
Andy Lutomirski
04d1d281dc x86/entry/32: Add an ASM_CLAC to entry_SYSENTER_32
Both before and after 5f310f739b ("x86/entry/32: Re-implement
SYSENTER using the new C path"), we relied on a uaccess very early
in the SYSENTER path to clear AC.  After that change, though, we can
potentially make it all the way into C code with AC set, which
enlarges the attack surface for SMAP bypass by doing SYSENTER with
AC set.

Strengthen the SMAP protection by addding the missing ASM_CLAC right
at the beginning.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/3e36be110724896e32a4a1fe73bacb349d3cba94.1456262295.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-02-24 08:43:04 +01:00
Josh Poimboeuf
058fb73274 x86/asm/entry: Create stack frames in thunk functions
Thunk functions are callable non-leaf functions that don't honor
CONFIG_FRAME_POINTER, which can result in bad stack traces.  Also they
aren't annotated as ELF callable functions which can confuse tooling.

Create stack frames for them when CONFIG_FRAME_POINTER is enabled and
add the ELF function type.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Reviewed-by: Borislav Petkov <bp@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Bernd Petrovitsch <bernd@petrovitsch.priv.at>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Chris J Arges <chris.j.arges@canonical.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michal Marek <mmarek@suse.cz>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Pedro Alves <palves@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: live-patching@vger.kernel.org
Link: http://lkml.kernel.org/r/4373e5bff459b9fd66ce5d45bfcc881a5c202643.1453405861.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-02-24 08:35:43 +01:00
Kees Cook
018ef8dcf3 x86/vdso: Mark the vDSO code read-only after init
The vDSO does not need to be writable after __init, so mark it as
__ro_after_init. The result kills the exploit method of writing to the
vDSO from kernel space resulting in userspace executing the modified code,
as shown here to bypass SMEP restrictions: http://itszn.com/blog/?p=21

The memory map (with added vDSO address reporting) shows the vDSO moving
into read-only memory:

Before:
	[    0.143067] vDSO @ ffffffff82004000
	[    0.143551] vDSO @ ffffffff82006000
	---[ High Kernel Mapping ]---
	0xffffffff80000000-0xffffffff81000000      16M                         pmd
	0xffffffff81000000-0xffffffff81800000       8M   ro     PSE     GLB x  pmd
	0xffffffff81800000-0xffffffff819f3000    1996K   ro             GLB x  pte
	0xffffffff819f3000-0xffffffff81a00000      52K   ro                 NX pte
	0xffffffff81a00000-0xffffffff81e00000       4M   ro     PSE     GLB NX pmd
	0xffffffff81e00000-0xffffffff81e05000      20K   ro             GLB NX pte
	0xffffffff81e05000-0xffffffff82000000    2028K   ro                 NX pte
	0xffffffff82000000-0xffffffff8214f000    1340K   RW             GLB NX pte
	0xffffffff8214f000-0xffffffff82281000    1224K   RW                 NX pte
	0xffffffff82281000-0xffffffff82400000    1532K   RW             GLB NX pte
	0xffffffff82400000-0xffffffff83200000      14M   RW     PSE     GLB NX pmd
	0xffffffff83200000-0xffffffffc0000000     974M                         pmd

After:
	[    0.145062] vDSO @ ffffffff81da1000
	[    0.146057] vDSO @ ffffffff81da4000
	---[ High Kernel Mapping ]---
	0xffffffff80000000-0xffffffff81000000      16M                         pmd
	0xffffffff81000000-0xffffffff81800000       8M   ro     PSE     GLB x  pmd
	0xffffffff81800000-0xffffffff819f3000    1996K   ro             GLB x  pte
	0xffffffff819f3000-0xffffffff81a00000      52K   ro                 NX pte
	0xffffffff81a00000-0xffffffff81e00000       4M   ro     PSE     GLB NX pmd
	0xffffffff81e00000-0xffffffff81e0b000      44K   ro             GLB NX pte
	0xffffffff81e0b000-0xffffffff82000000    2004K   ro                 NX pte
	0xffffffff82000000-0xffffffff8214c000    1328K   RW             GLB NX pte
	0xffffffff8214c000-0xffffffff8227e000    1224K   RW                 NX pte
	0xffffffff8227e000-0xffffffff82400000    1544K   RW             GLB NX pte
	0xffffffff82400000-0xffffffff83200000      14M   RW     PSE     GLB NX pmd
	0xffffffff83200000-0xffffffffc0000000     974M                         pmd

Based on work by PaX Team and Brad Spengler.

Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Andy Lutomirski <luto@kernel.org>
Acked-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brad Spengler <spender@grsecurity.net>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: David Brown <david.brown@linaro.org>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Emese Revfy <re.emese@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mathias Krause <minipli@googlemail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: PaX Team <pageexec@freemail.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kernel-hardening@lists.openwall.com
Cc: linux-arch <linux-arch@vger.kernel.org>
Link: http://lkml.kernel.org/r/1455748879-21872-7-git-send-email-keescook@chromium.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-02-22 08:51:39 +01:00
Andy Lutomirski
4e79e182b4 x86/entry/compat: Keep TS_COMPAT set during signal delivery
Signal delivery needs to know the sign of an interrupted syscall's
return value in order to detect -ERESTART variants.  Normally this
works independently of bitness because syscalls internally return
long.  Under ptrace, however, this can break, and syscall_get_error
is supposed to sign-extend regs->ax if needed.

We were clearing TS_COMPAT too early, though, and this prevented
sign extension, which subtly broke syscall restart under ptrace.

Reported-by: Robert O'Callahan <robert@ocallahan.org>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org # 4.3.x-
Fixes: c5c46f59e4 ("x86/entry: Add new, comprehensible entry and exit handlers written in C")
Link: http://lkml.kernel.org/r/cbce3cf545522f64eb37f5478cb59746230db3b5.1455142412.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-02-17 09:51:06 +01:00
Andy Lutomirski
bb56968a37 x86/syscalls/64: Mark sys_iopl() as using ptregs
sys_iopl() both reads and writes pt_regs->flags.  Mark it as using ptregs.

This isn't strictly necessary, as pt_regs->flags is available
even in the fast path, but this is very lightweight now that we
have syscall qualifiers and it could avoid some pain down the
road.

Reported-and-tested-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/3de0ca692fa8bf414c5e3d7afe3e6195d1a10e1f.1454261517.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-02-01 08:53:25 +01:00
Andy Lutomirski
eb2a54c327 x86/entry/64: Fix fast-path syscall return register state
I was fishing RIP (i.e. RCX) out of pt_regs->cx and RFLAGS (i.e.
R11) out of pt_regs->r11.  While it usually worked (pt_regs
started out with CX == IP and R11 == FLAGS), it was very
fragile.  In particular, it broke sys_iopl() because sys_iopl()
forgot to mark itself as using ptregs.

Undo that part of the syscall rework.  There was no compelling
reason to do it this way.  While I'm at it, load RCX and R11
before the other regs to be a little friendlier to the CPU, as
they will be the first of the reloaded registers to be used.

Reported-and-tested-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 1e423bff95 x86/entry/64: ("Migrate the 64-bit syscall slow path to C")
Link: http://lkml.kernel.org/r/a85f8360c397e48186a9bc3e565ad74307a7b011.1454261517.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-02-01 08:53:25 +01:00
Andy Lutomirski
b7765086b7 x86/entry/64: Fix an IRQ state error on ptregs-using syscalls
I messed up the IRQ state when jumping off the fast path due to
invocation of a ptregs-using syscall.  This bug shouldn't have
had any impact yet, but it would have caused problems with
subsequent context tracking cleanups.

Reported-and-tested-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 1e423bff95 x86/entry/64: ("Migrate the 64-bit syscall slow path to C")
Link: http://lkml.kernel.org/r/ab92cd365fb7b0a56869e920017790d96610fdca.1454261517.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-02-01 08:53:25 +01:00
Borislav Petkov
8c72530699 x86/vdso: Use static_cpu_has()
... and simplify and speed up a tad.

Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1453842730-28463-10-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-01-30 11:22:23 +01:00
Borislav Petkov
cd4d09ec6f x86/cpufeature: Carve out X86_FEATURE_*
Move them to a separate header and have the following
dependency:

  x86/cpufeatures.h <- x86/processor.h <- x86/cpufeature.h

This makes it easier to use the header in asm code and not
include the whole cpufeature.h and add guards for asm.

Suggested-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1453842730-28463-5-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-01-30 11:22:17 +01:00
Andy Lutomirski
1e423bff95 x86/entry/64: Migrate the 64-bit syscall slow path to C
This is more complicated than the 32-bit and compat cases
because it preserves an asm fast path for the case where the
callee-saved regs aren't needed in pt_regs and no entry or exit
work needs to be done.

This appears to slow down fastpath syscalls by no more than one
cycle on my Skylake laptop.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/ce2335a4d42dc164b24132ee5e8c7716061f947b.1454022279.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-01-29 09:46:38 +01:00
Andy Lutomirski
24d978b76f x86/entry/64: Stop using int_ret_from_sys_call in ret_from_fork
ret_from_fork is now open-coded and is no longer tangled up with
the syscall code.  This isn't so bad -- this adds very little
code, and IMO the result is much easier to understand.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/a0747e2a5e47084655a1e96351c545b755c41fa7.1454022279.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-01-29 09:46:38 +01:00
Andy Lutomirski
46eabf06c0 x86/entry/64: Call all native slow-path syscalls with full pt-regs
This removes all of the remaining asm syscall stubs except for
stub_ptregs_64.  Entries in the main syscall table are now all
callable from C.

The resulting asm is every bit as ridiculous as it looks.  The
next few patches will clean it up.  This patch is here to let
reviewers rest their brains and for bisection.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/a6b3801be0d505d50aefabda02d3b93efbfc9c73.1454022279.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-01-29 09:46:38 +01:00
Andy Lutomirski
302f5b260c x86/entry/64: Always run ptregs-using syscalls on the slow path
64-bit syscalls currently have an optimization in which they are
called with partial pt_regs.  A small handful require full
pt_regs.

In the 32-bit and compat cases, I cleaned this up by forcing
full pt_regs for all syscalls.  The performance hit doesn't
really matter as the affected system calls are fundamentally
heavy and this is the 32-bit compat case.

I want to clean up the 64-bit case as well, but I don't want to
hurt fast path performance.  To do that, I want to force the
syscalls that use pt_regs onto the slow path.  This will enable
us to make slow path syscalls be real ABI-compliant C functions.

Use the new syscall entry qualification machinery for this.
'stub_clone' is now 'stub_clone/ptregs'.

The next patch will eliminate the stubs, and we'll just have
'sys_clone/ptregs'.

As of this patch, two-phase entry tracing is no longer used.  It
has served its purpose (namely a huge speedup on some workloads
prior to more general opportunistic SYSRET support), and once
the dust settles I'll send patches to back it out.

The implementation is heavily based on a patch from Brian Gerst:

  http://lkml.kernel.org/g/1449666173-15366-1-git-send-email-brgerst@gmail.com

Originally-From: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/b9beda88460bcefec6e7d792bd44eca9b760b0c4.1454022279.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-01-29 09:46:38 +01:00
Andy Lutomirski
cfcbadb49d x86/syscalls: Add syscall entry qualifiers
This will let us specify something like 'sys_xyz/foo' instead of
'sys_xyz' in the syscall table, where the 'foo' qualifier conveys
some extra information to the C code.

The intent is to allow things like sys_execve/ptregs to indicate
that sys_execve() touches pt_regs.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/2de06e33dce62556b3ec662006fcb295504e296e.1454022279.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-01-29 09:46:38 +01:00
Andy Lutomirski
3e65654e3d x86/syscalls: Move compat syscall entry handling into syscalltbl.sh
Rather than duplicating the compat entry handling in all
consumers of syscalls_BITS.h, handle it directly in
syscalltbl.sh.  Now we generate entries in syscalls_32.h like:

__SYSCALL_I386(5, sys_open)
__SYSCALL_I386(5, compat_sys_open)

and all of its consumers implicitly get the right entry point.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/b7c2b501dc0e6e43050e916b95807c3e2e16e9bb.1454022279.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-01-29 09:46:37 +01:00
Andy Lutomirski
32324ce15e x86/syscalls: Remove __SYSCALL_COMMON and __SYSCALL_X32
The common/64/x32 distinction has no effect other than
determining which kernels actually support the syscall.  Move
the logic into syscalltbl.sh.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/58d4a95f40e43b894f93288b4a3633963d0ee22e.1454022279.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-01-29 09:46:37 +01:00
Andy Lutomirski
fba324744b x86/syscalls: Refactor syscalltbl.sh
This splits out the code to emit a syscall line.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1bfcbba991f5cfaa9291ff950a593daa972a205f.1454022279.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-01-29 09:46:37 +01:00
Ingo Molnar
76b36fa896 Linux 4.5-rc1
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Merge tag 'v4.5-rc1' into x86/asm, to refresh the branch before merging new changes

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-01-29 09:41:18 +01:00
Andrey Ryabinin
c6d308534a UBSAN: run-time undefined behavior sanity checker
UBSAN uses compile-time instrumentation to catch undefined behavior
(UB).  Compiler inserts code that perform certain kinds of checks before
operations that could cause UB.  If check fails (i.e.  UB detected)
__ubsan_handle_* function called to print error message.

So the most of the work is done by compiler.  This patch just implements
ubsan handlers printing errors.

GCC has this capability since 4.9.x [1] (see -fsanitize=undefined
option and its suboptions).
However GCC 5.x has more checkers implemented [2].
Article [3] has a bit more details about UBSAN in the GCC.

[1] - https://gcc.gnu.org/onlinedocs/gcc-4.9.0/gcc/Debugging-Options.html
[2] - https://gcc.gnu.org/onlinedocs/gcc/Debugging-Options.html
[3] - http://developerblog.redhat.com/2014/10/16/gcc-undefined-behavior-sanitizer-ubsan/

Issues which UBSAN has found thus far are:

Found bugs:

 * out-of-bounds access - 97840cb67f ("netfilter: nfnetlink: fix
   insufficient validation in nfnetlink_bind")

undefined shifts:

 * d48458d4a7 ("jbd2: use a better hash function for the revoke
   table")

 * 10632008b9 ("clockevents: Prevent shift out of bounds")

 * 'x << -1' shift in ext4 -
   http://lkml.kernel.org/r/<5444EF21.8020501@samsung.com>

 * undefined rol32(0) -
   http://lkml.kernel.org/r/<1449198241-20654-1-git-send-email-sasha.levin@oracle.com>

 * undefined dirty_ratelimit calculation -
   http://lkml.kernel.org/r/<566594E2.3050306@odin.com>

 * undefined roundown_pow_of_two(0) -
   http://lkml.kernel.org/r/<1449156616-11474-1-git-send-email-sasha.levin@oracle.com>

 * [WONTFIX] undefined shift in __bpf_prog_run -
   http://lkml.kernel.org/r/<CACT4Y+ZxoR3UjLgcNdUm4fECLMx2VdtfrENMtRRCdgHB2n0bJA@mail.gmail.com>

   WONTFIX here because it should be fixed in bpf program, not in kernel.

signed overflows:

 * 32a8df4e0b ("sched: Fix odd values in effective_load()
   calculations")

 * mul overflow in ntp -
   http://lkml.kernel.org/r/<1449175608-1146-1-git-send-email-sasha.levin@oracle.com>

 * incorrect conversion into rtc_time in rtc_time64_to_tm() -
   http://lkml.kernel.org/r/<1449187944-11730-1-git-send-email-sasha.levin@oracle.com>

 * unvalidated timespec in io_getevents() -
   http://lkml.kernel.org/r/<CACT4Y+bBxVYLQ6LtOKrKtnLthqLHcw-BMp3aqP3mjdAvr9FULQ@mail.gmail.com>

 * [NOTABUG] signed overflow in ktime_add_safe() -
   http://lkml.kernel.org/r/<CACT4Y+aJ4muRnWxsUe1CMnA6P8nooO33kwG-c8YZg=0Xc8rJqw@mail.gmail.com>

[akpm@linux-foundation.org: fix unused local warning]
[akpm@linux-foundation.org: fix __int128 build woes]
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Michal Marek <mmarek@suse.cz>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Yury Gribov <y.gribov@samsung.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Kostya Serebryany <kcc@google.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-20 17:09:18 -08:00
Alexander Kuleshov
2024315124 x86/asm/entry: Remove unused SAVE_ALL/RESTORE_ALL macros for !CONFIG_x86_64
SAVE_ALL and RESTORE_ALL macros for !CONFIG_X86_64 were
introduced in commit:

  1a338ac32 commit ('sched, x86: Optimize the preempt_schedule() call')

... and were used in the ___preempt_schedule() and ___preempt_schedule_context()
functions from the arch/x86/kernel/preempt.S.

But the arch/x86/kernel/preempt.S file was removed in the following commit:

  0ad6e3c5 commit ('x86: Speed up ___preempt_schedule*() by using THUNK helpers')

The ___preempt_schedule()/___preempt_schedule_context() functions were
reimplemeted and do not use SAVE_ALL/RESTORE_ALL anymore.

These macros have no users anymore, so we can remove them.

Signed-off-by: Alexander Kuleshov <kuleshovmail@gmail.com>
Acked-by: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Borislav Petkov <bp@suse.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1453126394-13717-1-git-send-email-kuleshovmail@gmail.com
[ Improved the changelog. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-01-19 08:24:03 +01:00
Linus Torvalds
10a0c0f059 Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 fixes from Ingo Molnar:
 "Misc changes:
   - fix lguest bug
   - fix /proc/meminfo output on certain configs
   - fix pvclock bug
   - fix reboot on certain iMacs by adding new reboot quirk
   - fix bootup crash
   - fix FPU boot line option parsing
   - add more x86 self-tests
   - small cleanups, documentation improvements, etc"

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/cpu/amd: Remove an unneeded condition in srat_detect_node()
  x86/vdso/pvclock: Protect STABLE check with the seqcount
  x86/mm: Improve switch_mm() barrier comments
  selftests/x86: Test __kernel_sigreturn and __kernel_rt_sigreturn
  x86/reboot/quirks: Add iMac10,1 to pci_reboot_dmi_table[]
  lguest: Map switcher text R/O
  x86/boot: Hide local labels in verify_cpu()
  x86/fpu: Disable AVX when eagerfpu is off
  x86/fpu: Disable MPX when eagerfpu is off
  x86/fpu: Disable XGETBV1 when no XSAVE
  x86/fpu: Fix early FPU command-line parsing
  x86/mm: Use PAGE_ALIGNED instead of IS_ALIGNED
  selftests/x86: Disable the ldt_gdt_64 test for now
  x86/mm/pat: Make split_page_count() check for empty levels to fix /proc/meminfo output
  x86/boot: Double BOOT_HEAP_SIZE to 64KB
  x86/mm: Add barriers and document switch_mm()-vs-flush synchronization
2016-01-14 11:57:22 -08:00
Andy Lutomirski
78fd8c7288 x86/vdso/pvclock: Protect STABLE check with the seqcount
If the clock becomes unstable while we're reading it, we need to
bail.  We can do this by simply moving the check into the
seqcount loop.

Reported-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Alexander Graf <agraf@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Radim Krcmar <rkrcmar@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/755dcedb17269e1d7ce12a9a713dea303835137e.1451949191.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-01-13 11:46:29 +01:00
Linus Torvalds
fce205e9da Merge branch 'work.copy_file_range' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull vfs copy_file_range updates from Al Viro:
 "Several series around copy_file_range/CLONE"

* 'work.copy_file_range' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  btrfs: use new dedupe data function pointer
  vfs: hoist the btrfs deduplication ioctl to the vfs
  vfs: wire up compat ioctl for CLONE/CLONE_RANGE
  cifs: avoid unused variable and label
  nfsd: implement the NFSv4.2 CLONE operation
  nfsd: Pass filehandle to nfs4_preprocess_stateid_op()
  vfs: pull btrfs clone API to vfs layer
  locks: new locks_mandatory_area calling convention
  vfs: Add vfs_copy_file_range() support for pagecache copies
  btrfs: add .copy_file_range file operation
  x86: add sys_copy_file_range to syscall tables
  vfs: add copy_file_range syscall and vfs helper
2016-01-12 16:30:34 -08:00
Andy Lutomirski
bd902c5362 x86/vdso: Disallow vvar access to vclock IO for never-used vclocks
It makes me uncomfortable that even modern systems grant every
process direct read access to the HPET.

While fixing this for real without regressing anything is a mess
(unmapping the HPET is tricky because we don't adequately track
all the mappings), we can do almost as well by tracking which
vclocks have ever been used and only allowing pages associated
with used vclocks to be faulted in.

This will cause rogue programs that try to peek at the HPET to
get SIGBUS instead on most systems.

We can't restrict faults to vclock pages that are associated
with the currently selected vclock due to a race: a process
could start to access the HPET for the first time and race
against a switch away from the HPET as the current clocksource.
We can't segfault the process trying to peek at the HPET in this
case, even though the process isn't going to do anything useful
with the data.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/e79d06295625c02512277737ab55085a498ac5d8.1451446564.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-01-12 11:59:35 +01:00
Andy Lutomirski
a48a704261 x86/vdso: Use ->fault() instead of remap_pfn_range() for the vvar mapping
This is IMO much less ugly, and it also opens the door to
disallowing unprivileged userspace HPET access on systems with
usable TSCs.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/c19c2909e5ee3c3d8742f916586676bb7c40345f.1451446564.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-01-12 11:59:35 +01:00
Andy Lutomirski
05ef76b20f x86/vdso: Use .fault for the vDSO text mapping
The old scheme for mapping the vDSO text is rather complicated.
vdso2c generates a struct vm_special_mapping and a blank .pages
array of the correct size for each vdso image.  Init code in
vdso/vma.c populates the .pages array for each vDSO image, and
the mapping code selects the appropriate struct
vm_special_mapping.

With .fault, we can use a less roundabout approach: vdso_fault()
just returns the appropriate page for the selected vDSO image.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/f886954c186bafd74e1b967c8931d852ae199aa2.1451446564.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-01-12 11:59:34 +01:00
Andy Lutomirski
352b78c62f x86/vdso: Track each mm's loaded vDSO image as well as its base
As we start to do more intelligent things with the vDSO at
runtime (as opposed to just at mm initialization time), we'll
need to know which vDSO is in use.

In principle, we could guess based on the mm type, but that's
over-complicated and error-prone.  Instead, just track it in the
mmu context.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/c99ac48681bad709ca7ad5ee899d9042a3af6b00.1451446564.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-01-12 11:59:34 +01:00
Linus Torvalds
88cbfd0711 Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 asm updates from Ingo Molnar:
 "The main changes in this cycle were:

   - vDSO and asm entry improvements (Andy Lutomirski)

   - Xen paravirt entry enhancements (Boris Ostrovsky)

   - asm entry labels enhancement (Borislav Petkov)

   - and other misc changes (Thomas Gleixner, me)"

* 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/vsdo: Fix build on PARAVIRT_CLOCK=y, KVM_GUEST=n
  Revert "x86/kvm: On KVM re-enable (e.g. after suspend), update clocks"
  x86/entry/64_compat: Make labels local
  x86/platform/uv: Include clocksource.h for clocksource_touch_watchdog()
  x86/vdso: Enable vdso pvclock access on all vdso variants
  x86/vdso: Remove pvclock fixmap machinery
  x86/vdso: Get pvclock data from the vvar VMA instead of the fixmap
  x86, vdso, pvclock: Simplify and speed up the vdso pvclock reader
  x86/kvm: On KVM re-enable (e.g. after suspend), update clocks
  x86/entry/64: Bypass enter_from_user_mode on non-context-tracking boots
  x86/asm: Add asm macros for static keys/jump labels
  x86/asm: Error out if asm/jump_label.h is included inappropriately
  context_tracking: Switch to new static_branch API
  x86/entry, x86/paravirt: Remove the unused usergs_sysret32 PV op
  x86/paravirt: Remove the unused irq_enable_sysexit pv op
  x86/xen: Avoid fast syscall path for Xen PV guests
2016-01-11 15:58:16 -08:00
Andy Lutomirski
30bfa7b348 x86/entry: Restore traditional SYSENTER calling convention
It turns out that some Android versions hardcode the SYSENTER
calling convention.  This is buggy and will cause problems no
matter what the kernel does.  Nonetheless, we should try to
support it.

Credit goes to Linus for pointing out a clean way to handle
the SYSENTER/SYSCALL clobber differences while preserving
straightforward DWARF annotations.

I believe that the original offending Android commit was:

https://android.googlesource.com/platform%2Fbionic/+/7dc3684d7a2587e43e6d2a8e0e3f39bf759bd535

Reported-by: Qiuxu Zhuo <qiuxu.zhuo@intel.com>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-and-tested-by: Borislav Petkov <bp@alien8.de>
Cc: <mark.gross@intel.com>
Cc: Su Tao <tao.su@intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: <frank.wang@intel.com>
Cc: <borun.fu@intel.com>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Mingwei Shi <mingwei.shi@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2015-12-21 16:05:01 +01:00
Andy Lutomirski
6a613ac6bc x86/entry: Fix some comments
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-and-tested-by: Borislav Petkov <bp@alien8.de>
Cc: <mark.gross@intel.com>
Cc: Su Tao <tao.su@intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: <qiuxu.zhuo@intel.com>
Cc: <frank.wang@intel.com>
Cc: <borun.fu@intel.com>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Mingwei Shi <mingwei.shi@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2015-12-21 16:05:01 +01:00
Boris Ostrovsky
91e2eea98f x86/xen: Avoid fast syscall path for Xen PV guests
After 32-bit syscall rewrite, and specifically after commit:

  5f310f739b ("x86/entry/32: Re-implement SYSENTER using the new C path")

... the stack frame that is passed to xen_sysexit is no longer a
"standard" one (i.e. it's not pt_regs).

Since we end up calling xen_iret from xen_sysexit we don't need
to fix up the stack and instead follow entry_SYSENTER_32's IRET
path directly to xen_iret.

We can do the same thing for compat mode even though stack does
not need to be fixed. This will allow us to drop usergs_sysret32
paravirt op (in the subsequent patch)

Suggested-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: Borislav Petkov <bp@suse.de>
Acked-by: Andy Lutomirski <luto@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: david.vrabel@citrix.com
Cc: konrad.wilk@oracle.com
Cc: virtualization@lists.linux-foundation.org
Cc: xen-devel@lists.xenproject.org
Link: http://lkml.kernel.org/r/1447970147-1733-2-git-send-email-boris.ostrovsky@oracle.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2015-12-19 09:55:52 +01:00
Borislav Petkov
f74acf0e43 x86/entry/64_compat: Make labels local
... so that they don't appear as symbols in the final ELF.

Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1449916077-6506-1-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-12-14 09:28:48 +01:00
Andy Lutomirski
76480a6a55 x86/vdso: Enable vdso pvclock access on all vdso variants
Now that pvclock doesn't require access to the fixmap, all vdso
variants can use it.

The kernel side isn't wired up for 32-bit kernels yet, but this
covers 32-bit and x32 userspace on 64-bit kernels.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/a7ef693b7a4c88dd2173dc1d4bf6bc27023626eb.1449702533.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-12-11 08:56:03 +01:00
Andy Lutomirski
cc1e24fdb0 x86/vdso: Remove pvclock fixmap machinery
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/4933029991103ae44672c82b97a20035f5c1fe4f.1449702533.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-12-11 08:56:03 +01:00
Andy Lutomirski
dac16fba6f x86/vdso: Get pvclock data from the vvar VMA instead of the fixmap
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/9d37826fdc7e2d2809efe31d5345f97186859284.1449702533.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-12-11 08:56:03 +01:00
Andy Lutomirski
6b078f5de7 x86, vdso, pvclock: Simplify and speed up the vdso pvclock reader
The pvclock vdso code was too abstracted to understand easily
and excessively paranoid.  Simplify it for a huge speedup.

This opens the door for additional simplifications, as the vdso
no longer accesses the pvti for any vcpu other than vcpu 0.

Before, vclock_gettime using kvm-clock took about 45ns on my
machine. With this change, it takes 29ns, which is almost as
fast as the pure TSC implementation.

Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/6b51dcc41f1b101f963945c5ec7093d72bdac429.1449702533.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-12-11 08:56:02 +01:00
Zach Brown
cb4c4e8091 x86: add sys_copy_file_range to syscall tables
Add sys_copy_file_range to the x86 syscall tables.

Signed-off-by: Zach Brown <zab@redhat.com>
[Anna Schumaker: Update syscall number in syscall_32.tbl]
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-12-01 14:00:54 -05:00
Andy Lutomirski
478dc89cf3 x86/entry/64: Bypass enter_from_user_mode on non-context-tracking boots
On CONFIG_CONTEXT_TRACKING kernels that have context tracking
disabled at runtime (which includes most distro kernels), we
still have the overhead of a call to enter_from_user_mode in
interrupt and exception entries.

If jump labels are available, this uses the jump label
infrastructure to skip the call.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/73ee804fff48cd8c66b65b724f9f728a11a8c686.1447361906.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-11-24 09:56:44 +01:00
Ingo Molnar
49b2410631 Merge branch 'x86/urgent' into x86/asm, to pick up dependent fixes
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-11-24 09:55:11 +01:00
Andy Lutomirski
f10750536f x86/entry/64: Fix irqflag tracing wrt context tracking
Paolo pointed out that enter_from_user_mode could be called
while irqflags were traced as though IRQs were on.

In principle, this could confuse lockdep.  It doesn't cause any
problems that I've seen in any configuration, but if I build
with CONFIG_DEBUG_LOCKDEP=y, enable a nohz_full CPU, and add
code like:

	if (irqs_disabled()) {
		spin_lock(&something);
		spin_unlock(&something);
	}

to the top of enter_from_user_mode, then lockdep will complain
without this fix.  It seems that lockdep's irqflags sanity
checks are too weak to detect this bug without forcing the
issue.

This patch adds one byte to normal kernels, and it's IMO a bit
ugly. I haven't spotted a better way to do this yet, though.
The issue is that we can't do TRACE_IRQS_OFF until after SWAPGS
(if needed), but we're also supposed to do it before calling C
code.

An alternative approach would be to call trace_hardirqs_off in
enter_from_user_mode.  That would be less code and would not
bloat normal kernels at all, but it would be harder to see how
the code worked.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/86237e362390dfa6fec12de4d75a238acb0ae787.1447361906.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-11-24 09:55:02 +01:00
Boris Ostrovsky
75ef82190d x86/entry, x86/paravirt: Remove the unused usergs_sysret32 PV op
As result of commit "x86/xen: Avoid fast syscall path for Xen PV
guests", usergs_sysret32 pv op is not called by Xen PV guests
anymore and since they were the only ones who used it we can
safely remove it.

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: Borislav Petkov <bp@suse.de>
Acked-by: Andy Lutomirski <luto@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: david.vrabel@citrix.com
Cc: konrad.wilk@oracle.com
Cc: virtualization@lists.linux-foundation.org
Cc: xen-devel@lists.xenproject.org
Link: http://lkml.kernel.org/r/1447970147-1733-4-git-send-email-boris.ostrovsky@oracle.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-11-23 10:48:16 +01:00
Boris Ostrovsky
88c15ec90f x86/paravirt: Remove the unused irq_enable_sysexit pv op
As result of commit "x86/xen: Avoid fast syscall path for Xen PV
guests", the irq_enable_sysexit pv op is not called by Xen PV guests
anymore and since they were the only ones who used it we can
safely remove it.

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: Borislav Petkov <bp@suse.de>
Acked-by: Andy Lutomirski <luto@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: david.vrabel@citrix.com
Cc: konrad.wilk@oracle.com
Cc: virtualization@lists.linux-foundation.org
Cc: xen-devel@lists.xenproject.org
Link: http://lkml.kernel.org/r/1447970147-1733-3-git-send-email-boris.ostrovsky@oracle.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-11-23 10:48:16 +01:00
Boris Ostrovsky
5fdf5d37f4 x86/xen: Avoid fast syscall path for Xen PV guests
After 32-bit syscall rewrite, and specifically after commit:

  5f310f739b ("x86/entry/32: Re-implement SYSENTER using the new C path")

... the stack frame that is passed to xen_sysexit is no longer a
"standard" one (i.e. it's not pt_regs).

Since we end up calling xen_iret from xen_sysexit we don't need
to fix up the stack and instead follow entry_SYSENTER_32's IRET
path directly to xen_iret.

We can do the same thing for compat mode even though stack does
not need to be fixed. This will allow us to drop usergs_sysret32
paravirt op (in the subsequent patch)

Suggested-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: Borislav Petkov <bp@suse.de>
Acked-by: Andy Lutomirski <luto@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: david.vrabel@citrix.com
Cc: konrad.wilk@oracle.com
Cc: virtualization@lists.linux-foundation.org
Cc: xen-devel@lists.xenproject.org
Link: http://lkml.kernel.org/r/1447970147-1733-2-git-send-email-boris.ostrovsky@oracle.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-11-23 10:48:16 +01:00
Eric B Munson
a8ca5d0ecb mm: mlock: add new mlock system call
With the refactored mlock code, introduce a new system call for mlock.
The new call will allow the user to specify what lock states are being
added.  mlock2 is trivial at the moment, but a follow on patch will add a
new mlock state making it useful.

Signed-off-by: Eric B Munson <emunson@akamai.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Linus Torvalds
639ab3eb38 Merge branch 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 mm changes from Ingo Molnar:
 "The main changes are: continued PAT work by Toshi Kani, plus a new
  boot time warning about insecure RWX kernel mappings, by Stephen
  Smalley.

  The new CONFIG_DEBUG_WX=y warning is marked default-y if
  CONFIG_DEBUG_RODATA=y is already eanbled, as a special exception, as
  these bugs are hard to notice and this check already found several
  live bugs"

* 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/mm: Warn on W^X mappings
  x86/mm: Fix no-change case in try_preserve_large_page()
  x86/mm: Fix __split_large_page() to handle large PAT bit
  x86/mm: Fix try_preserve_large_page() to handle large PAT bit
  x86/mm: Fix gup_huge_p?d() to handle large PAT bit
  x86/mm: Fix slow_virt_to_phys() to handle large PAT bit
  x86/mm: Fix page table dump to show PAT bit
  x86/asm: Add pud_pgprot() and pmd_pgprot()
  x86/asm: Fix pud/pmd interfaces to handle large PAT bit
  x86/asm: Add pud/pmd mask interfaces to handle large PAT bit
  x86/asm: Move PUD_PAGE macros to page_types.h
  x86/vdso32: Define PGTABLE_LEVELS to 32bit VDSO
2015-11-03 21:23:56 -08:00
Andy Lutomirski
3bd29515d1 x86/entry/32: Fix FS and GS restore in opportunistic SYSEXIT
We either need to restore them before popping and thus changing
ESP, or we need to adjust the offsets.  The former is simpler.

Reported-and-tested-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 5f310f739b x86/entry/32: ("Re-implement SYSENTER using the new C path")
Link: http://lkml.kernel.org/r/461e5c7d8fa3821529893a4893ac9c4bc37f9e17.1445035014.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-10-18 12:11:16 +02:00
Andy Lutomirski
657c1eea00 x86/entry/32: Fix entry_INT80_32() to expect interrupts to be on
When I rewrote entry_INT80_32, I thought that int80 was an
interrupt gate.  It's a trap gate.  *facepalm*

Thanks to Brian Gerst for pointing out that it's better to
change the entry code than to change the gate type.

Suggested-by: Brian Gerst <brgerst@gmail.com>
Reported-and-tested-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 150ac78d63 ("x86/entry/32: Switch INT80 to the new C syscall path")
Link: http://lkml.kernel.org/r/dc09d9b574a5c1dcca996847875c73f8341ce0ad.1445035014.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-10-18 12:11:16 +02:00
Borislav Petkov
374a3a3916 x86/entry/64/compat: Document sysenter_fix_flags's reason for existence
The code under the label can normally be inline, without the
jumping back and forth but the latter is an optimization.

Document that.

Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20151009170859.GA24266@pd.tnic
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-10-11 11:06:40 +02:00
Andy Lutomirski
f5e6a9753a x86/entry: Split and inline syscall_return_slowpath()
GCC is unable to properly optimize functions that have a very
short likely case and a longer and register-heavier cold part --
it fails to sink all of the register saving and stack frame
setup code into the unlikely part.

Help it out with syscall_return_slowpath() by splitting it into
two parts and inline the hot part.

Saves 6 cycles for compat syscalls.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/0f773a894ab15c589ac794c2d34ca6ba9b5335c9.1444091585.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-10-09 09:41:13 +02:00
Andy Lutomirski
39b48e575e x86/entry: Split and inline prepare_exit_to_usermode()
GCC is unable to properly optimize functions that have a very
short likely case and a longer and register-heavier cold part --
it fails to sink all of the register saving and stack frame
setup code into the unlikely part.

Help it out with prepare_exit_to_usermode() by splitting it into
two parts and inline the hot part.

Saves 6-8 cycles for compat syscalls.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/9fc53eda4a5b924070952f12fa4ae3e477640a07.1444091585.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-10-09 09:41:13 +02:00
Andy Lutomirski
dd636071c3 x86/entry: Use pt_regs_to_thread_info() in syscall entry tracing
It generates simpler and faster code than current_thread_info().

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/a3b6633e7dcb9f673c1b619afae602d29d27d2cf.1444091585.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-10-09 09:41:12 +02:00
Andy Lutomirski
4aabd140f9 x86/entry: Hide two syscall entry assertions behind CONFIG_DEBUG_ENTRY
This shaves a few cycles off the slow paths.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/ce383fa9e129286ce6da6e00b53acd4c9fb5d06a.1444091585.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-10-09 09:41:12 +02:00
Andy Lutomirski
c68ca6787b x86/entry: Micro-optimize compat fast syscall arg fetch
We're following a 32-bit pointer, and the uaccess code isn't
smart enough to figure out that the access_ok() check isn't
needed.

This saves about three cycles on a cache-hot fast syscall.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/bdff034e2f23c5eb974c760cf494cb5bddce8f29.1444091585.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-10-09 09:41:12 +02:00
Andy Lutomirski
33c52129f4 x86/entry: Force inlining of 32-bit syscall code
On systems that support fast syscalls, we only really care about
the performance of the fast syscall path.  Forcibly inline it
and add a likely annotation.

This saves 4-6 cycles.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/8472036ff1f4b426b4c4c3e3d0b3bf5264407c0c.1444091585.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-10-09 09:41:12 +02:00
Andy Lutomirski
460d12453e x86/entry: Make irqs_disabled checks in exit code depend on lockdep
These checks are quite slow.  Disable them in non-lockdep
kernels to reduce the performance hit.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/eccff2a154ae6fb50f40228901003a6e9c24f3d0.1444091585.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-10-09 09:41:11 +02:00
Andy Lutomirski
8b13c2552f x86/entry: Remove unnecessary IRQ twiddling in fast 32-bit syscalls
This is slightly messy, but it eliminates an unnecessary cli;sti
pair.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/22f34b1096694a37326f36c53407b8dd90f37948.1444091585.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-10-09 09:41:11 +02:00
Andy Lutomirski
5f310f739b x86/entry/32: Re-implement SYSENTER using the new C path
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/5b99659e8be70f3dd10cd8970a5c90293d9ad9a7.1444091585.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-10-09 09:41:10 +02:00
Andy Lutomirski
150ac78d63 x86/entry/32: Switch INT80 to the new C syscall path
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/a7e8d8df96838eae3208dd0441023f3ce7a81831.1444091585.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-10-09 09:41:10 +02:00
Andy Lutomirski
39e8701f33 x86/entry/32: Open-code return tracking from fork and kthreads
syscall_exit is going away, and return tracing is just a
function call now, so open-code the two non-syscall 32-bit
users.

While we're at it, update the big register layout comment.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/a6b3c472fda7cda0e368c3ccd553dea7447dfdd2.1444091585.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-10-09 09:41:10 +02:00
Andy Lutomirski
7841b40871 x86/entry/compat: Implement opportunistic SYSRETL for compat syscalls
If CS, SS and IP are as expected and FLAGS is compatible with
SYSRETL, then return from fast compat syscalls (both SYSCALL and
SYSENTER) using SYSRETL.

Unlike native 64-bit opportunistic SYSRET, this is not invisible
to user code: RCX and R8-R15 end up in a different state than
shown saved in pt_regs.  To compensate, we only do this when
returning to the vDSO fast syscall return path.  This won't
interfere with syscall restart, as we won't use SYSRETL when
returning to the INT80 restart instruction.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/aa15e49db33773eb10b73d73466b6d5466d7856a.1444091585.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-10-09 09:41:10 +02:00
Andy Lutomirski
a474e67c91 x86/vdso/compat: Wire up SYSENTER and SYSCSALL for compat userspace
What, you didn't realize that SYSENTER and SYSCALL were actually
the same thing? :)

Unlike the old code, this actually passes the ptrace_syscall_32
test on AMD systems.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/b74615af58d785aa02d917213ec64e2022a2c796.1444091585.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-10-09 09:41:09 +02:00
Andy Lutomirski
710246df58 x86/entry: Add C code for fast system call entries
This handles both SYSENTER and SYSCALL.  The asm glue will take
care of the differences.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/6041a58a9b8ef6d2522ab4350deb1a1945eb563f.1444091585.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-10-09 09:41:09 +02:00
Andy Lutomirski
ee08c6bd31 x86/entry/64/compat: Migrate the body of the syscall entry to C
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/a2f0fce68feeba798a24339b5a7ec1ec2dd9eaf7.1444091585.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-10-09 09:41:09 +02:00
Andy Lutomirski
bd2d3a3ba6 x86/entry: Add do_syscall_32(), a C function to do 32-bit syscalls
System calls are really quite simple.  Add a helper to call
a 32-bit system call.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/a77ed179834c27da436fb4a7fb23c8ee77abc11c.1444091585.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-10-09 09:41:08 +02:00
Andy Lutomirski
eb974c6256 x86/syscalls: Give sys_call_ptr_t a useful type
Syscalls are asmlinkage functions (on 32-bit kernels), take six
args of type unsigned long, and return long.  Note that uml
could probably be slightly cleaned up on top of this patch.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/4d3ecc4a169388d47009175408b2961961744e6f.1444091585.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-10-09 09:41:08 +02:00
Andy Lutomirski
034042cc1e x86/entry/syscalls: Move syscall table declarations into asm/syscalls.h
The header was missing some compat declarations.

Also make sys_call_ptr_t have a consistent type.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/3166aaff0fb43897998fcb6ef92991533f8c5c6c.1444091585.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-10-09 09:41:08 +02:00
Andy Lutomirski
8169aff611 x86/entry/64/compat: Set up full pt_regs for all compat syscalls
This is conceptually simpler.  More importantly, it eliminates
the PTREGSCALL and execve stubs, which were not compatible with
the C ABI.  This means that C code can call through the compat
syscall table.

The execve stubs are a bit subtle.  They did two things: they
cleared some registers and they forced slow-path return.
Neither is necessary any more: elf_common_init clears the extra
registers and start_thread calls force_iret().

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/f95b7f7dfaacf88a8cae85bb06226cae53769287.1444091584.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-10-09 09:41:07 +02:00
Andy Lutomirski
2ec67971fa x86/entry/64/compat: Remove most of the fast system call machinery
We now have only one code path that calls through the compat
syscall table.  This will make it much more pleasant to change
the pt_regs vs register calling convention, which we need to do
to move the call into C.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/320cda5573cefdc601b955d23fbe8f36c085432d.1444091584.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-10-09 09:41:07 +02:00
Andy Lutomirski
c5f638ac90 x86/entry/64/compat: Remove audit optimizations
These audit optimizations are messy and hard to maintain.  We'll
get a similar effect from opportunistic sysret when fast compat
system calls are re-implemented.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/0bcca79ac7ff835d0e5a38725298865b01347a82.1444091584.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-10-09 09:41:07 +02:00
Andy Lutomirski
e62a254a1f x86/entry/64/compat: Disable SYSENTER and SYSCALL32 entries
We've disabled the vDSO helpers to call them, so turn off the
entries entirely (temporarily) in preparation for cleaning them
up.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/8d6e84bf651519289dc532dcc230adfabbd2a3eb.1444091584.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-10-09 09:41:07 +02:00
Andy Lutomirski
8242c6c84a x86/vdso/32: Save extra registers in the INT80 vsyscall path
The goal is to integrate the SYSENTER and SYSCALL32 entry paths
with the INT80 path.  SYSENTER clobbers ESP and EIP.  SYSCALL32
clobbers ECX (and, invisibly, R11).  SYSRETL (long mode to
compat mode) clobbers ECX and, invisibly, R11.  SYSEXIT (which
we only need for native 32-bit) clobbers ECX and EDX.

This means that we'll need to provide ESP to the kernel in a
register (I chose ECX, since it's only needed for SYSENTER) and
we need to provide the args that normally live in ECX and EDX in
memory.

The epilogue needs to restore ECX and EDX, since user code
relies on regs being preserved.

We don't need to do anything special about EIP, since the kernel
already knows where we are.  The kernel will eventually need to
know where int $0x80 lands, so add a vdso_image entry for it.

The only user-visible effect of this code is that ptrace-induced
changes to ECX and EDX during fast syscalls will be lost.  This
is already the case for the SYSENTER path.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/b860925adbee2d2627a0671fbfe23a7fd04127f8.1444091584.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-10-09 09:41:06 +02:00
Andy Lutomirski
29c0ce9508 x86/vdso: Replace hex int80 CFI annotations with GAS directives
Maintaining the current CFI annotations written in R'lyehian is
difficult for most of us.  Translate them to something a little
closer to English.

This will remove the CFI data for kernels built with extremely
old versions of binutils.  I think this is a fair tradeoff for
the ability for mortals to edit the asm.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/ae3ff4ff5278b4bfc1e1dab368823469866d4b71.1444091584.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-10-09 09:41:06 +02:00
Andy Lutomirski
f24f910884 x86/vdso: Define BUILD_VDSO while building and emit .eh_frame in asm
For the vDSO, user code wants runtime unwind info.  Make sure
that, if we use .cfi directives, we generate it.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/16e29ad8855e6508197000d8c41f56adb00d7580.1444091584.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-10-09 09:41:05 +02:00
Andy Lutomirski
0a6d1fa0d2 x86/vdso: Remove runtime 32-bit vDSO selection
32-bit userspace will now always see the same vDSO, which is
exactly what used to be the int80 vDSO.  Subsequent patches will
clean it up and make it support SYSENTER and SYSCALL using
alternatives.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/e7e6b3526fa442502e6125fe69486aab50813c32.1444091584.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-10-07 11:34:08 +02:00
Andy Lutomirski
b611acf473 x86/entry/64/compat: After SYSENTER, move STI after the NT fixup
We eventually want to make it all the way into C code before
enabling interrupts.  We need to rework our flags handling
slightly to delay enabling interrupts.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/35d24d2a9305da3182eab7b2cdfd32902e90962c.1444091584.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-10-07 11:34:08 +02:00
Andy Lutomirski
72f924783b x86/entry, locking/lockdep: Move lockdep_sys_exit() to prepare_exit_to_usermode()
Rather than worrying about exactly where LOCKDEP_SYS_EXIT should
go in the asm code, add it to prepare_exit_from_usermode() and
remove all of the asm calls that are followed by
prepare_exit_to_usermode().

LOCKDEP_SYS_EXIT now appears only in the syscall fast paths.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/1736ebe948b845e68120b86b89091f3ec27f5e8e.1444091584.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-10-07 11:34:07 +02:00
Andy Lutomirski
dd27f998f0 x86/entry/64/compat: Fix SYSENTER's NT flag before user memory access
Clearing NT is part of the prologue, whereas loading up arg6
makes more sense to think about as part of syscall processing.
Reorder them.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/19eb235828b2d2a52c53459e09f2974e15e65a35.1444091584.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-10-07 11:34:07 +02:00
Ingo Molnar
25a9a924c0 Merge branch 'linus' into x86/asm, to pick up fixes before applying new changes
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-10-07 11:24:24 +02:00
Ingo Molnar
38a413cbc2 Linux 4.3-rc3
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Merge tag 'v4.3-rc3' into x86/mm, to pick up fixes before applying new changes

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-10-06 10:56:54 +02:00
Andy Lutomirski
83c133cf11 x86/nmi/64: Fix a paravirt stack-clobbering bug in the NMI code
The NMI entry code that switches to the normal kernel stack needs to
be very careful not to clobber any extra stack slots on the NMI
stack.  The code is fine under the assumption that SWAPGS is just a
normal instruction, but that assumption isn't really true.  Use
SWAPGS_UNSAFE_STACK instead.

This is part of a fix for some random crashes that Sasha saw.

Fixes: 9b6e6a8334 ("x86/nmi/64: Switch stacks on userspace NMI entry")
Reported-and-tested-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/974bc40edffdb5c2950a5c4977f821a446b76178.1442791737.git.luto@kernel.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2015-09-22 22:40:36 +02:00
Andy Lutomirski
fc57a7c680 x86/paravirt: Replace the paravirt nop with a bona fide empty function
PARAVIRT_ADJUST_EXCEPTION_FRAME generates this code (using nmi as an
example, trimmed for readability):

    ff 15 00 00 00 00       callq  *0x0(%rip)        # 2796 <nmi+0x6>
              2792: R_X86_64_PC32     pv_irq_ops+0x2c

That's a call through a function pointer to regular C function that
does nothing on native boots, but that function isn't protected
against kprobes, isn't marked notrace, and is certainly not
guaranteed to preserve any registers if the compiler is feeling
perverse.  This is bad news for a CLBR_NONE operation.

Of course, if everything works correctly, once paravirt ops are
patched, it gets nopped out, but what if we hit this code before
paravirt ops are patched in?  This can potentially cause breakage
that is very difficult to debug.

A more subtle failure is possible here, too: if _paravirt_nop uses
the stack at all (even just to push RBP), it will overwrite the "NMI
executing" variable if it's called in the NMI prologue.

The Xen case, perhaps surprisingly, is fine, because it's already
written in asm.

Fix all of the cases that default to paravirt_nop (including
adjust_exception_frame) with a big hammer: replace paravirt_nop with
an asm function that is just a ret instruction.

The Xen case may have other problems, so document them.

This is part of a fix for some random crashes that Sasha saw.

Reported-and-tested-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/8f5d2ba295f9d73751c33d97fda03e0495d9ade0.1442791737.git.luto@kernel.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2015-09-22 22:40:28 +02:00
Toshi Kani
fb535ccb30 x86/vdso32: Define PGTABLE_LEVELS to 32bit VDSO
In case of CONFIG_X86_64, vdso32/vclock_gettime.c fakes a 32-bit
non-PAE kernel configuration by re-defining it to CONFIG_X86_32.
However, it does not re-define CONFIG_PGTABLE_LEVELS leaving it
as 4 levels.

This mismatch leads <asm/pgtable_type.h> to NOT include <asm-generic/
pgtable-nopud.h> and <asm-generic/pgtable-nopmd.h>, which will cause
compile errors when a later patch enhances <asm/pgtable_type.h> to
use PUD_SHIFT and PMD_SHIFT.  These -nopud & -nopmd headers define
these SHIFTs for the 32-bit non-PAE kernel.

Fix it by re-defining CONFIG_PGTABLE_LEVELS to 2 levels.

Signed-off-by: Toshi Kani <toshi.kani@hpe.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Juergen Gross <jgross@suse.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Konrad Wilk <konrad.wilk@oracle.com>
Cc: Robert Elliot <elliott@hpe.com>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/1442514264-12475-2-git-send-email-toshi.kani@hpe.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2015-09-22 21:27:32 +02:00
Borislav Petkov
93f13a9f96 x86/entry/vsyscall: Fix undefined symbol warning
Commit:

  3dc33bd30f ("x86/entry/vsyscall: Add CONFIG to control default")

did the ifdef/elif thing but GCC doesn't like that:

  arch/x86/entry/vsyscall/vsyscall_64.c:44:7: warning: "CONFIG_LEGACY_VSYSCALL_NONE" is not defined [-Wundef]
   #elif CONFIG_LEGACY_VSYSCALL_NONE
         ^

Use defined() instead.

Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20150921074829.GA3550@pd.tnic
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-09-21 09:56:59 +02:00
Kees Cook
3dc33bd30f x86/entry/vsyscall: Add CONFIG to control default
Most modern systems can run with vsyscall=none. In an effort to
provide a way for build-time defaults to lack legacy settings,
this adds a new CONFIG to select the type of vsyscall mapping to
use, similar to the existing "vsyscall" command line parameter.

Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20150813005519.GA11696@www.outflux.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-09-20 10:31:06 +02:00
Mathieu Desnoyers
5b25b13ab0 sys_membarrier(): system-wide memory barrier (generic, x86)
Here is an implementation of a new system call, sys_membarrier(), which
executes a memory barrier on all threads running on the system.  It is
implemented by calling synchronize_sched().  It can be used to
distribute the cost of user-space memory barriers asymmetrically by
transforming pairs of memory barriers into pairs consisting of
sys_membarrier() and a compiler barrier.  For synchronization primitives
that distinguish between read-side and write-side (e.g.  userspace RCU
[1], rwlocks), the read-side can be accelerated significantly by moving
the bulk of the memory barrier overhead to the write-side.

The existing applications of which I am aware that would be improved by
this system call are as follows:

* Through Userspace RCU library (http://urcu.so)
  - DNS server (Knot DNS) https://www.knot-dns.cz/
  - Network sniffer (http://netsniff-ng.org/)
  - Distributed object storage (https://sheepdog.github.io/sheepdog/)
  - User-space tracing (http://lttng.org)
  - Network storage system (https://www.gluster.org/)
  - Virtual routers (https://events.linuxfoundation.org/sites/events/files/slides/DPDK_RCU_0MQ.pdf)
  - Financial software (https://lkml.org/lkml/2015/3/23/189)

Those projects use RCU in userspace to increase read-side speed and
scalability compared to locking.  Especially in the case of RCU used by
libraries, sys_membarrier can speed up the read-side by moving the bulk of
the memory barrier cost to synchronize_rcu().

* Direct users of sys_membarrier
  - core dotnet garbage collector (https://github.com/dotnet/coreclr/issues/198)

Microsoft core dotnet GC developers are planning to use the mprotect()
side-effect of issuing memory barriers through IPIs as a way to implement
Windows FlushProcessWriteBuffers() on Linux.  They are referring to
sys_membarrier in their github thread, specifically stating that
sys_membarrier() is what they are looking for.

To explain the benefit of this scheme, let's introduce two example threads:

Thread A (non-frequent, e.g. executing liburcu synchronize_rcu())
Thread B (frequent, e.g. executing liburcu
rcu_read_lock()/rcu_read_unlock())

In a scheme where all smp_mb() in thread A are ordering memory accesses
with respect to smp_mb() present in Thread B, we can change each
smp_mb() within Thread A into calls to sys_membarrier() and each
smp_mb() within Thread B into compiler barriers "barrier()".

Before the change, we had, for each smp_mb() pairs:

Thread A                    Thread B
previous mem accesses       previous mem accesses
smp_mb()                    smp_mb()
following mem accesses      following mem accesses

After the change, these pairs become:

Thread A                    Thread B
prev mem accesses           prev mem accesses
sys_membarrier()            barrier()
follow mem accesses         follow mem accesses

As we can see, there are two possible scenarios: either Thread B memory
accesses do not happen concurrently with Thread A accesses (1), or they
do (2).

1) Non-concurrent Thread A vs Thread B accesses:

Thread A                    Thread B
prev mem accesses
sys_membarrier()
follow mem accesses
                            prev mem accesses
                            barrier()
                            follow mem accesses

In this case, thread B accesses will be weakly ordered. This is OK,
because at that point, thread A is not particularly interested in
ordering them with respect to its own accesses.

2) Concurrent Thread A vs Thread B accesses

Thread A                    Thread B
prev mem accesses           prev mem accesses
sys_membarrier()            barrier()
follow mem accesses         follow mem accesses

In this case, thread B accesses, which are ensured to be in program
order thanks to the compiler barrier, will be "upgraded" to full
smp_mb() by synchronize_sched().

* Benchmarks

On Intel Xeon E5405 (8 cores)
(one thread is calling sys_membarrier, the other 7 threads are busy
looping)

1000 non-expedited sys_membarrier calls in 33s =3D 33 milliseconds/call.

* User-space user of this system call: Userspace RCU library

Both the signal-based and the sys_membarrier userspace RCU schemes
permit us to remove the memory barrier from the userspace RCU
rcu_read_lock() and rcu_read_unlock() primitives, thus significantly
accelerating them. These memory barriers are replaced by compiler
barriers on the read-side, and all matching memory barriers on the
write-side are turned into an invocation of a memory barrier on all
active threads in the process. By letting the kernel perform this
synchronization rather than dumbly sending a signal to every process
threads (as we currently do), we diminish the number of unnecessary wake
ups and only issue the memory barriers on active threads. Non-running
threads do not need to execute such barrier anyway, because these are
implied by the scheduler context switches.

Results in liburcu:

Operations in 10s, 6 readers, 2 writers:

memory barriers in reader:    1701557485 reads, 2202847 writes
signal-based scheme:          9830061167 reads,    6700 writes
sys_membarrier:               9952759104 reads,     425 writes
sys_membarrier (dyn. check):  7970328887 reads,     425 writes

The dynamic sys_membarrier availability check adds some overhead to
the read-side compared to the signal-based scheme, but besides that,
sys_membarrier slightly outperforms the signal-based scheme. However,
this non-expedited sys_membarrier implementation has a much slower grace
period than signal and memory barrier schemes.

Besides diminishing the number of wake-ups, one major advantage of the
membarrier system call over the signal-based scheme is that it does not
need to reserve a signal. This plays much more nicely with libraries,
and with processes injected into for tracing purposes, for which we
cannot expect that signals will be unused by the application.

An expedited version of this system call can be added later on to speed
up the grace period. Its implementation will likely depend on reading
the cpu_curr()->mm without holding each CPU's rq lock.

This patch adds the system call to x86 and to asm-generic.

[1] http://urcu.so

membarrier(2) man page:

MEMBARRIER(2)              Linux Programmer's Manual             MEMBARRIER(2)

NAME
       membarrier - issue memory barriers on a set of threads

SYNOPSIS
       #include <linux/membarrier.h>

       int membarrier(int cmd, int flags);

DESCRIPTION
       The cmd argument is one of the following:

       MEMBARRIER_CMD_QUERY
              Query  the  set  of  supported commands. It returns a bitmask of
              supported commands.

       MEMBARRIER_CMD_SHARED
              Execute a memory barrier on all threads running on  the  system.
              Upon  return from system call, the caller thread is ensured that
              all running threads have passed through a state where all memory
              accesses  to  user-space  addresses  match program order between
              entry to and return from the system  call  (non-running  threads
              are de facto in such a state). This covers threads from all pro=E2=80=90
              cesses running on the system.  This command returns 0.

       The flags argument needs to be 0. For future extensions.

       All memory accesses performed  in  program  order  from  each  targeted
       thread is guaranteed to be ordered with respect to sys_membarrier(). If
       we use the semantic "barrier()" to represent a compiler barrier forcing
       memory  accesses  to  be performed in program order across the barrier,
       and smp_mb() to represent explicit memory barriers forcing full  memory
       ordering  across  the barrier, we have the following ordering table for
       each pair of barrier(), sys_membarrier() and smp_mb():

       The pair ordering is detailed as (O: ordered, X: not ordered):

                              barrier()   smp_mb() sys_membarrier()
              barrier()          X           X            O
              smp_mb()           X           O            O
              sys_membarrier()   O           O            O

RETURN VALUE
       On success, these system calls return zero.  On error, -1 is  returned,
       and errno is set appropriately. For a given command, with flags
       argument set to 0, this system call is guaranteed to always return the
       same value until reboot.

ERRORS
       ENOSYS System call is not implemented.

       EINVAL Invalid arguments.

Linux                             2015-04-15                     MEMBARRIER(2)

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nicholas Miell <nmiell@comcast.net>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Alan Cox <gnomes@lxorguk.ukuu.org.uk>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Stephen Hemminger <stephen@networkplumber.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Pranith Kumar <bobby.prani@gmail.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-11 15:21:34 -07:00
Kirill A. Shutemov
7cbea8dc01 mm: mark most vm_operations_struct const
With two exceptions (drm/qxl and drm/radeon) all vm_operations_struct
structs should be constant.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-10 13:29:01 -07:00
Andrea Arcangeli
1380fca084 userfaultfd: activate syscall
This activates the userfaultfd syscall.

[sfr@canb.auug.org.au: activate syscall fix]
[akpm@linux-foundation.org: don't enable userfaultfd on powerpc]
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Pavel Emelyanov <xemul@parallels.com>
Cc: Sanidhya Kashyap <sanidhya.gatech@gmail.com>
Cc: zhang.zhanghailiang@huawei.com
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Andres Lagar-Cavilla <andreslc@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Hugh Dickins <hughd@google.com>
Cc: Peter Feiner <pfeiner@google.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: "Huangpeng (Peter)" <peter.huangpeng@huawei.com>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-04 16:54:41 -07:00
Ingo Molnar
a5dd192496 Merge branch 'x86/urgent' into x86/asm to fix up conflicts and to pick up fixes
Conflicts:
	arch/x86/entry/entry_64_compat.S
	arch/x86/math-emu/get_address.c

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-18 09:39:47 +02:00
Linus Torvalds
cd88ec2317 x86: fix error handling for 32-bit compat out-of-range system call numbers
Commit 3f5159a922 ("x86/asm/entry/32: Update -ENOSYS handling to match
the 64-bit logic") broke the ENOSYS handling for the 32-bit compat case.
The proper error return value was never loaded into %rax, except if
things just happened to go through the audit paths, which ended up
reloading the return value.

This moves the loading or %rax into the normal system call path, just to
make sure the error case triggers it.  It's kind of sad, since it adds a
useless instruction to reload the register to the fast path, but it's
not like that single load from the stack is going to be noticeable.

Reported-by: David Drysdale <drysdale@google.com>
Tested-by: Kees Cook <keescook@chromium.org>
Acked-by: Andy Lutomirski <luto@amacapital.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-08-13 16:19:44 -07:00
Andy Lutomirski
6b7e26547f x86/vdso: Emit a GNU hash
Some dynamic loaders may be slightly faster if a GNU hash is
available.  Strangely, this seems to have no effect at all on
the vdso size.

This is unlikely to have any measurable effect on the time it
takes to resolve vdso symbols (since there are so few of them).
In some contexts, it can be a win for a different reason: if
every DSO has a GNU hash section, then libc can avoid
calculating SysV hashes at all.  Both musl and glibc appear to
have this optimization.

It's plausible that this breaks some ancient glibc version.  If
so, then, depending on what glibc versions break, we could
either require COMPAT_VDSO for them or consider reverting.

Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Isaac Dunham <ibid.ag@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Nathan Lynch <nathan_lynch@mentor.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: musl@lists.openwall.com <musl@lists.openwall.com>
Link: http://lkml.kernel.org/r/fd56cc057a2d62ab31c56a48d04fccb435b3fd4f.1438897382.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-08 10:42:07 +02:00
Andy Lutomirski
88cd622f92 x86/entry: Remove do_notify_resume(), syscall_trace_leave(), and their TIF masks
They are no longer used. Good riddance!

Deleting the TIF_ macros is really nice. It was never clear why
there were so many variants.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eric Paris <eparis@parisplace.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/22c61682f446628573dde0f1d573ab821677e06da.1438378274.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-05 10:54:35 +02:00
Andy Lutomirski
5d73fc7099 x86/entry/32: Migrate to C exit path
This removes the hybrid asm-and-C implementation of exit work.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eric Paris <eparis@parisplace.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/2baa438619ea6c027b40ec9fceacca52f09c74d09.1438378274.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-05 10:54:35 +02:00
Andy Lutomirski
c5f69fde26 x86/entry/32: Remove 32-bit syscall audit optimizations
The asm audit optimizations are ugly and obfuscate the code too
much. Remove them.

This will regress performance if syscall auditing is enabled on
32-bit kernels and SYSENTER is in use. If this becomes a
problem, interested parties are encouraged to implement the
equivalent of the 64-bit opportunistic SYSRET optimization.

Alternatively, a case could be made that, on 32-bit kernels, a
less messy asm audit optimization could be done. 32-bit kernels
don't have the complicated partial register saving tricks that
64-bit kernels have, so the SYSENTER post-syscall path could
just call the audit hooks directly.  Any reimplementation of
this ought to demonstrate that it only calls the audit hook once
per syscall, though, which does not currently appear to be true.

Someone would have to make the case that doing so would be
better than implementing opportunistic SYSEXIT, though.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eric Paris <eparis@parisplace.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/212be39dd8c90b44c4b7bbc678128d6b88bdb9912.1438378274.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-05 10:54:35 +02:00
Brian Gerst
5ed92a8ab7 x86/vm86: Use the normal pt_regs area for vm86
Change to use the normal pt_regs area to enter and exit vm86
mode.  This is done by increasing the padding at the top of the
stack to make room for the extra vm86 segment slots in the IRET
frame.  It then saves the 32-bit regs in the off-stack vm86
data, and copies in the vm86 regs.  Exiting back to 32-bit mode
does the reverse.  This allows removing the hacks to jump
directly into the exit asm code due to having to change the
stack pointer.  Returning normally from the vm86 syscall and the
exception handlers allows things like ptrace and auditing to work properly.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
Acked-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1438148483-11932-5-git-send-email-brgerst@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-07-31 13:31:09 +02:00
Ingo Molnar
5b929bd11d Merge branch 'x86/urgent' into x86/asm, before applying dependent patches
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-07-31 10:23:35 +02:00
Denys Vlasenko
c0c3322e98 x86/asm/entry/32: Revert 'Do not use R9 in SYSCALL32' commit
This change reverts most of commit 53e9accf0f 'Do not use R9 in
SYSCALL32'. I don't yet understand how, but code in that commit
sometimes fails to preserve EBP.

See https://bugzilla.kernel.org/show_bug.cgi?id=101061
"Problems while executing 32-bit code on AMD64"

Reported-and-tested-by: Krzysztof A. Sobiecki <sobkas@gmail.com>
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Will Drewry <wad@chromium.org>
Cc: Kees Cook <keescook@chromium.org>
CC: x86@kernel.org
Link: http://lkml.kernel.org/r/1437740203-11552-1-git-send-email-dvlasenk@redhat.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2015-07-24 16:36:00 +02:00
Andy Lutomirski
9dea5dc921 x86/entry/syscalls: Wire up 32-bit direct socket calls
On x86_64, there's no socketcall syscall; instead all of the
socket calls are real syscalls.  For 32-bit programs, we're
stuck offering the socketcall syscall, but it would be nice to
expose the direct calls as well.  This will enable seccomp to
filter socket calls (for new userspace only, but that's fine for
some applications) and it will provide a tiny performance boost.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Alexander Larsson <alexl@redhat.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Cosimo Cecchi <cosimo@endlessm.com>
Cc: Dan Nicholson <nicholson@endlessm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rajalakshmi Srinivasaraghavan <raji@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tulio Magno Quites Machado Filho <tuliom@linux.vnet.ibm.com>
Cc: libc-alpha <libc-alpha@sourceware.org>
Link: http://lkml.kernel.org/r/cb5138299d37d5800e2d135b01a7667fa6115854.1436912629.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-07-21 10:11:04 +02:00
Andy Lutomirski
d132803e6c x86/entry: Fix _TIF_USER_RETURN_NOTIFY check in prepare_exit_to_usermode
Linus noticed that the early return check was missing
_TIF_USER_RETURN_NOTIFY.  If the only work flag was
_TIF_USER_RETURN_NOTIFY, we'd skip user return notifiers.  Fix
it. (This is the only missing bit.)

This fixes double faults on a KVM host.  It's the same issue as
last time, except that this time it's very easy to trigger.
Apparently no one uses -next as a KVM host.

( I'm still not quite sure what it is that KVM does that blows up
  so badly if we miss a user return notifier.  My best guess is that KVM
  lets KERNEL_GS_BASE (i.e. the user's gs base) be negative and fixes
  it up in a user return notifier.  If we actually end up in user mode
  with a negative gs base, we blow up pretty badly. )

Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: c5c46f59e4 ("x86/entry: Add new, comprehensible entry and exit handlers written in C")
Link: http://lkml.kernel.org/r/3f801104d24ee7a6bb1446408d9950777aa63277.1436995419.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-07-17 16:08:22 +02:00
Andy Lutomirski
a97439aa1a x86/entry/64, x86/nmi/64: Add CONFIG_DEBUG_ENTRY NMI testing code
It turns out to be rather tedious to test the NMI nesting code.
Make it easier: add a new CONFIG_DEBUG_ENTRY option that causes
the NMI handler to pre-emptively unmask NMIs.

With this option set, errors in the repeat_nmi logic or failures
to detect that we're in a nested NMI will result in quick panics
under perf (especially if multiple counters are running at high
frequency) instead of requiring an unusual workload that
generates page faults or breakpoints inside NMIs.

I called it CONFIG_DEBUG_ENTRY instead of CONFIG_DEBUG_NMI_ENTRY
because I want to add new non-NMI checks elsewhere in the entry
code in the future, and I'd rather not add too many new config
options or add this option and then immediately rename it.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Borislav Petkov <bp@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-07-17 12:50:14 +02:00
Andy Lutomirski
36f1a77b3a x86/nmi/64: Make the "NMI executing" variable more consistent
Currently, "NMI executing" is one the first time an outermost
NMI hits repeat_nmi and zero thereafter.  Change it to be zero
each time for consistency.

This is intended to help NMI handling fail harder if it's buggy.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Borislav Petkov <bp@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-07-17 12:50:13 +02:00
Andy Lutomirski
23a781e987 x86/nmi/64: Minor asm simplification
Replace LEA; MOV with an equivalent SUB.  This saves one
instruction.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Borislav Petkov <bp@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-07-17 12:50:13 +02:00
Andy Lutomirski
810bc075f7 x86/nmi/64: Use DF to avoid userspace RSP confusing nested NMI detection
We have a tricky bug in the nested NMI code: if we see RSP
pointing to the NMI stack on NMI entry from kernel mode, we
assume that we are executing a nested NMI.

This isn't quite true.  A malicious userspace program can point
RSP at the NMI stack, issue SYSCALL, and arrange for an NMI to
happen while RSP is still pointing at the NMI stack.

Fix it with a sneaky trick.  Set DF in the region of code that
the RSP check is intended to detect.  IRET will clear DF
atomically.

( Note: other than paravirt, there's little need for all this
  complexity. We could check RIP instead of RSP. )

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Borislav Petkov <bp@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-07-17 12:50:12 +02:00
Andy Lutomirski
a27507ca2d x86/nmi/64: Reorder nested NMI checks
Check the repeat_nmi .. end_repeat_nmi special case first.  The
next patch will rework the RSP check and, as a side effect, the
RSP check will no longer detect repeat_nmi .. end_repeat_nmi, so
we'll need this ordering of the checks.

Note: this is more subtle than it appears.  The check for
repeat_nmi .. end_repeat_nmi jumps straight out of the NMI code
instead of adjusting the "iret" frame to force a repeat.  This
is necessary, because the code between repeat_nmi and
end_repeat_nmi sets "NMI executing" and then writes to the
"iret" frame itself.  If a nested NMI comes in and modifies the
"iret" frame while repeat_nmi is also modifying it, we'll end up
with garbage.  The old code got this right, as does the new
code, but the new code is a bit more explicit.

If we were to move the check right after the "NMI executing"
check, then we'd get it wrong and have random crashes.

( Because the "NMI executing" check would jump to the code that would
  modify the "iret" frame without checking if the interrupted NMI was
  currently modifying it. )

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Borislav Petkov <bp@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-07-17 12:50:12 +02:00
Andy Lutomirski
0b22930eba x86/nmi/64: Improve nested NMI comments
I found the nested NMI documentation to be difficult to follow.
Improve the comments.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Borislav Petkov <bp@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-07-17 12:50:11 +02:00
Andy Lutomirski
9b6e6a8334 x86/nmi/64: Switch stacks on userspace NMI entry
Returning to userspace is tricky: IRET can fail, and ESPFIX can
rearrange the stack prior to IRET.

The NMI nesting fixup relies on a precise stack layout and
atomic IRET.  Rather than trying to teach the NMI nesting fixup
to handle ESPFIX and failed IRET, punt: run NMIs that came from
user mode on the normal kernel stack.

This will make some nested NMIs visible to C code, but the C
code is okay with that.

As a side effect, this should speed up perf: it eliminates an
RDMSR when NMIs come from user mode.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Reviewed-by: Borislav Petkov <bp@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-07-17 12:50:11 +02:00
Andy Lutomirski
0e181bb581 x86/nmi/64: Remove asm code that saves CR2
Now that do_nmi saves CR2, we don't need to save it in asm.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Borislav Petkov <bp@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-07-17 12:50:11 +02:00
Andy Lutomirski
8f7f06b87a x86/entry/64: Fix IRQ state confusion and related warning on compat syscalls with CONFIG_AUDITSYSCALL=n
int_ret_from_sys_call now expects IRQs to be enabled.  I got
this right in the real sysexit_audit and sysretl_audit asm
paths, but I missed it in the #defined-away versions when
CONFIG_AUDITSYSCALL=n.  This is a straightforward fix for
CONFIG_AUDITSYSCALL=n

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 29ea1b258b ("x86/entry/64: Migrate 64-bit and compat syscalls to the new exit handlers and remove old assembly code")
Link: http://lkml.kernel.org/r/25cf0a01e01c6008118dd8f8d9f043020416700c.1436291493.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-07-08 21:10:25 +02:00
Andy Lutomirski
06a7b36c7b x86/entry: Remove SCHEDULE_USER and asm/context-tracking.h
SCHEDULE_USER is no longer used, and asm/context-tracking.h
contained nothing else.  Remove the header entirely.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Denys Vlasenko <vda.linux@googlemail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: paulmck@linux.vnet.ibm.com
Link: http://lkml.kernel.org/r/854e9b45f69af20e26c47099eb236321563ebcee.1435952415.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-07-07 10:59:09 +02:00
Andy Lutomirski
02bc7768fe x86/asm/entry/64: Migrate error and IRQ exit work to C and remove old assembly code
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Denys Vlasenko <vda.linux@googlemail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: paulmck@linux.vnet.ibm.com
Link: http://lkml.kernel.org/r/60e90901eee611e59e958bfdbbe39969b4f88fe5.1435952415.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-07-07 10:59:08 +02:00
Andy Lutomirski
a586f98e97 x86/asm/entry/64: Simplify IRQ stack pt_regs handling
There's no need for both RSI and RDI to point to the original stack.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Denys Vlasenko <vda.linux@googlemail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: paulmck@linux.vnet.ibm.com
Link: http://lkml.kernel.org/r/3a0481f809dd340c7d3f54ce3fd6d66ef2a578cd.1435952415.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-07-07 10:59:08 +02:00
Andy Lutomirski
ff467594f2 x86/asm/entry/64: Save all regs on interrupt entry
To prepare for the big rewrite of the error and interrupt exit
paths, we will need pt_regs completely filled in.

It's already completely filled in when error_exit runs, so rearrange
interrupt handling to match it.  This will slow down interrupt
handling very slightly (eight instructions), but the
simplification it enables will be more than worth it.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Denys Vlasenko <vda.linux@googlemail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: paulmck@linux.vnet.ibm.com
Link: http://lkml.kernel.org/r/d8a766a7f558b30e6e01352854628a2d9943460c.1435952415.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-07-07 10:59:07 +02:00
Andy Lutomirski
29ea1b258b x86/entry/64: Migrate 64-bit and compat syscalls to the new exit handlers and remove old assembly code
These need to be migrated together, as the compat case used to
jump into the middle of the 64-bit exit code.

Remove the old assembly code.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Denys Vlasenko <vda.linux@googlemail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: paulmck@linux.vnet.ibm.com
Link: http://lkml.kernel.org/r/d4d1d70de08ac3640badf50048a9e8f18fe2497f.1435952415.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-07-07 10:59:07 +02:00
Andy Lutomirski
cb6f64ed5a x86/entry/64: Really create an error-entry-from-usermode code path
In 539f511365 ("x86/asm/entry/64: Disentangle error_entry/exit
gsbase/ebx/usermode code"), I arranged the code slightly wrong
-- IRET faults would skip the code path that was intended to
execute on all error entries from user mode.  Fix it up.

While we're at it, make all the labels in error_entry local.

This does not fix a bug, but we'll need it, and it slightly
shrinks the code.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Denys Vlasenko <vda.linux@googlemail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: paulmck@linux.vnet.ibm.com
Link: http://lkml.kernel.org/r/91e17891e49fa3d61357eadc451529ad48143ee1.1435952415.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-07-07 10:59:07 +02:00
Andy Lutomirski
c5c46f59e4 x86/entry: Add new, comprehensible entry and exit handlers written in C
The current x86 entry and exit code, written in a mixture of assembly and
C code, is incomprehensible due to being open-coded in a lot of places
without coherent documentation.

It appears to work primary by luck and duct tape: i.e. obvious runtime
failures were fixed on-demand, without re-thinking the design.

Due to those reasons our confidence level in that code is low, and it is
very difficult to incrementally improve.

Add new code written in C, in preparation for simply deleting the old
entry code.

prepare_exit_to_usermode() is a new function that will handle all
slow path exits to user mode.  It is called with IRQs disabled
and it leaves us in a state in which it is safe to immediately
return to user mode.  IRQs must not be re-enabled at any point
after prepare_exit_to_usermode() returns and user mode is actually
entered. (We can, of course, fail to enter user mode and treat
that failure as a fresh entry to kernel mode.)

All callers of do_notify_resume() will be migrated to call
prepare_exit_to_usermode() instead; prepare_exit_to_usermode() needs
to do everything that do_notify_resume() does today, but it also
takes care of scheduling and context tracking.  Unlike
do_notify_resume(), it does not need to be called in a loop.

syscall_return_slowpath() is exactly what it sounds like: it will
be called on any syscall exit slow path. It will replace
syscall_trace_leave() and it calls prepare_exit_to_usermode() on the
way out.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Denys Vlasenko <vda.linux@googlemail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: paulmck@linux.vnet.ibm.com
Link: http://lkml.kernel.org/r/c57c8b87661a4152801d7d3786eac2d1a2f209dd.1435952415.git.luto@kernel.org
[ Improved the changelog a bit. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-07-07 10:59:06 +02:00
Andy Lutomirski
feed36cde0 x86/entry: Add enter_from_user_mode() and use it in syscalls
Changing the x86 context tracking hooks is dangerous because
there are no good checks that we track our context correctly.
Add a helper to check that we're actually in CONTEXT_USER when
we enter from user mode and wire it up for syscall entries.

Subsequent patches will wire this up for all non-NMI entries as
well.  NMIs are their own special beast and cannot currently
switch overall context tracking state.  Instead, they have their
own special RCU hooks.

This is a tiny speedup if !CONFIG_CONTEXT_TRACKING (removes a
branch) and a tiny slowdown if CONFIG_CONTEXT_TRACING (adds a
layer of indirection).  Eventually, we should fix up the core
context tracking code to supply a function that does what we
want (and can be much simpler than user_exit), which will enable
us to get rid of the extra call.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Denys Vlasenko <vda.linux@googlemail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: paulmck@linux.vnet.ibm.com
Link: http://lkml.kernel.org/r/853b42420066ec3fb856779cdc223a6dcb5d355b.1435952415.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-07-07 10:59:06 +02:00
Andy Lutomirski
1f484aa690 x86/entry: Move C entry and exit code to arch/x86/entry/common.c
The entry and exit C helpers were confusingly scattered between
ptrace.c and signal.c, even though they aren't specific to
ptrace or signal handling.  Move them together in a new file.

This change just moves code around.  It doesn't change anything.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Denys Vlasenko <vda.linux@googlemail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: paulmck@linux.vnet.ibm.com
Link: http://lkml.kernel.org/r/324d686821266544d8572423cc281f961da445f4.1435952415.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-07-07 10:59:05 +02:00
Andy Lutomirski
5e99cb7c35 x86/entry/64/compat: Fix bad fast syscall arg failure path
If user code does SYSCALL32 or SYSENTER without a valid stack,
then our attempt to determine the syscall args will result in a
failed uaccess fault.  Previously, we would try to recover by
jumping to the syscall exit code, but we'd run the syscall exit
work even though we never made it to the syscall entry work.

Clean it up by treating the failure path as a non-syscall entry
and exit pair.

This fixes strace's output when running the syscall_arg_fault
test. Without this fix, strace would get out of sync and would
fail to associate syscall entries with syscall exits.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Denys Vlasenko <vda.linux@googlemail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: paulmck@linux.vnet.ibm.com
Link: http://lkml.kernel.org/r/903010762c07a3d67df914fea2da84b52b0f8f1d.1435952415.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-07-07 10:58:30 +02:00
Brian Gerst
c338867d0e x86/compat: Check for both 32-bit compat and x32 in get_gate_vma()
Change this to CONFIG_COMPAT so both 32-bit compat and x32 will
do the check.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
Acked-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1434974121-32575-8-git-send-email-brgerst@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-07-06 15:28:57 +02:00
Brian Gerst
ab8b82ee6d x86/compat: Don't build the 32-bit VDSO if not needed
Build the 32-bit vdso only for native 32-bit or 32-bit compat is
enabled.  x32 should not force it to build.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1434974121-32575-7-git-send-email-brgerst@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-07-06 15:28:56 +02:00
Andy Lutomirski
03b9730b76 x86/asm/tsc: Add rdtsc_ordered() and use it in trivial call sites
rdtsc_barrier(); rdtsc() is an unnecessary mouthful and requires
more thought than should be necessary. Add an rdtsc_ordered()
helper and replace the trivial call sites with it.

This should not change generated code. The duplication of the
fence asm is temporary.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Huang Rui <ray.huang@amd.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Len Brown <lenb@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kvm ML <kvm@vger.kernel.org>
Link: http://lkml.kernel.org/r/dddbf98a2af53312e9aa73a5a2b1622fe5d6f52b.1434501121.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-07-06 15:23:29 +02:00
Andy Lutomirski
4ea1636b04 x86/asm/tsc: Rename native_read_tsc() to rdtsc()
Now that there is no paravirt TSC, the "native" is
inappropriate. The function does RDTSC, so give it the obvious
name: rdtsc().

Suggested-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Huang Rui <ray.huang@amd.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Len Brown <lenb@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kvm ML <kvm@vger.kernel.org>
Link: http://lkml.kernel.org/r/fd43e16281991f096c1e4d21574d9e1402c62d39.1434501121.git.luto@kernel.org
[ Ported it to v4.2-rc1. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-07-06 15:23:28 +02:00
Andy Lutomirski
c6e5ca35c4 x86/asm/tsc: Inline native_read_tsc() and remove __native_read_tsc()
In the following commit:

  cdc7957d19 ("x86: move native_read_tsc() offline")

... native_read_tsc() was moved out of line, presumably for some
now-obsolete vDSO-related reason. Undo it.

The entire rdtsc, shl, or sequence is only 11 bytes, and calls
via rdtscl() and similar helpers were already inlined.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Huang Rui <ray.huang@amd.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Len Brown <lenb@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kvm ML <kvm@vger.kernel.org>
Link: http://lkml.kernel.org/r/d05ffe2aaf8468ca475ebc00efad7b2fa174af19.1434501121.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-07-06 15:23:25 +02:00
Denys Vlasenko
c73e36b775 x86/asm/entry/32: Replace RESTORE_RSI_RDI with open-coded 32-bit reads
This doesn't change much, but uses shorter 32-bit insns:

        -48 8b 74 24 68         mov    0x68(%rsp),%rsi
        -48 8b 7c 24 70         mov    0x70(%rsp),%rdi
        -48 8b 54 24 60         mov    0x60(%rsp),%rdx
        +8b 54 24 60            mov    0x60(%rsp),%edx
        +8b 74 24 68            mov    0x68(%rsp),%esi
        +8b 7c 24 70            mov    0x70(%rsp),%edi

and does the loads in pt_regs order.

Since these are the only uses of RESTORE_RSI_RDI[_RDX], drop
these macros.

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Drewry <wad@chromium.org>
Link: http://lkml.kernel.org/r/1435954742-2545-1-git-send-email-dvlasenk@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-07-06 14:56:50 +02:00
Linus Torvalds
d70b3ef54c Merge branch 'x86-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 core updates from Ingo Molnar:
 "There were so many changes in the x86/asm, x86/apic and x86/mm topics
  in this cycle that the topical separation of -tip broke down somewhat -
  so the result is a more traditional architecture pull request,
  collected into the 'x86/core' topic.

  The topics were still maintained separately as far as possible, so
  bisectability and conceptual separation should still be pretty good -
  but there were a handful of merge points to avoid excessive
  dependencies (and conflicts) that would have been poorly tested in the
  end.

  The next cycle will hopefully be much more quiet (or at least will
  have fewer dependencies).

  The main changes in this cycle were:

   * x86/apic changes, with related IRQ core changes: (Jiang Liu, Thomas
     Gleixner)

     - This is the second and most intrusive part of changes to the x86
       interrupt handling - full conversion to hierarchical interrupt
       domains:

          [IOAPIC domain]   -----
                                 |
          [MSI domain]      --------[Remapping domain] ----- [ Vector domain ]
                                 |   (optional)          |
          [HPET MSI domain] -----                        |
                                                         |
          [DMAR domain]     -----------------------------
                                                         |
          [Legacy domain]   -----------------------------

       This now reflects the actual hardware and allowed us to distangle
       the domain specific code from the underlying parent domain, which
       can be optional in the case of interrupt remapping.  It's a clear
       separation of functionality and removes quite some duct tape
       constructs which plugged the remap code between ioapic/msi/hpet
       and the vector management.

     - Intel IOMMU IRQ remapping enhancements, to allow direct interrupt
       injection into guests (Feng Wu)

   * x86/asm changes:

     - Tons of cleanups and small speedups, micro-optimizations.  This
       is in preparation to move a good chunk of the low level entry
       code from assembly to C code (Denys Vlasenko, Andy Lutomirski,
       Brian Gerst)

     - Moved all system entry related code to a new home under
       arch/x86/entry/ (Ingo Molnar)

     - Removal of the fragile and ugly CFI dwarf debuginfo annotations.
       Conversion to C will reintroduce many of them - but meanwhile
       they are only getting in the way, and the upstream kernel does
       not rely on them (Ingo Molnar)

     - NOP handling refinements. (Borislav Petkov)

   * x86/mm changes:

     - Big PAT and MTRR rework: making the code more robust and
       preparing to phase out exposing direct MTRR interfaces to drivers -
       in favor of using PAT driven interfaces (Toshi Kani, Luis R
       Rodriguez, Borislav Petkov)

     - New ioremap_wt()/set_memory_wt() interfaces to support
       Write-Through cached memory mappings.  This is especially
       important for good performance on NVDIMM hardware (Toshi Kani)

   * x86/ras changes:

     - Add support for deferred errors on AMD (Aravind Gopalakrishnan)

       This is an important RAS feature which adds hardware support for
       poisoned data.  That means roughly that the hardware marks data
       which it has detected as corrupted but wasn't able to correct, as
       poisoned data and raises an APIC interrupt to signal that in the
       form of a deferred error.  It is the OS's responsibility then to
       take proper recovery action and thus prolonge system lifetime as
       far as possible.

     - Add support for Intel "Local MCE"s: upcoming CPUs will support
       CPU-local MCE interrupts, as opposed to the traditional system-
       wide broadcasted MCE interrupts (Ashok Raj)

     - Misc cleanups (Borislav Petkov)

   * x86/platform changes:

     - Intel Atom SoC updates

  ... and lots of other cleanups, fixlets and other changes - see the
  shortlog and the Git log for details"

* 'x86-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (222 commits)
  x86/hpet: Use proper hpet device number for MSI allocation
  x86/hpet: Check for irq==0 when allocating hpet MSI interrupts
  x86/mm/pat, drivers/infiniband/ipath: Use arch_phys_wc_add() and require PAT disabled
  x86/mm/pat, drivers/media/ivtv: Use arch_phys_wc_add() and require PAT disabled
  x86/platform/intel/baytrail: Add comments about why we disabled HPET on Baytrail
  genirq: Prevent crash in irq_move_irq()
  genirq: Enhance irq_data_to_desc() to support hierarchy irqdomain
  iommu, x86: Properly handle posted interrupts for IOMMU hotplug
  iommu, x86: Provide irq_remapping_cap() interface
  iommu, x86: Setup Posted-Interrupts capability for Intel iommu
  iommu, x86: Add cap_pi_support() to detect VT-d PI capability
  iommu, x86: Avoid migrating VT-d posted interrupts
  iommu, x86: Save the mode (posted or remapped) of an IRTE
  iommu, x86: Implement irq_set_vcpu_affinity for intel_ir_chip
  iommu: dmar: Provide helper to copy shared irte fields
  iommu: dmar: Extend struct irte for VT-d Posted-Interrupts
  iommu: Add new member capability to struct irq_remap_ops
  x86/asm/entry/64: Disentangle error_entry/exit gsbase/ebx/usermode code
  x86/asm/entry/32: Shorten __audit_syscall_entry() args preparation
  x86/asm/entry/32: Explain reloading of registers after __audit_syscall_entry()
  ...
2015-06-22 17:59:09 -07:00
Andy Lutomirski
539f511365 x86/asm/entry/64: Disentangle error_entry/exit gsbase/ebx/usermode code
The error_entry/error_exit code to handle gsbase and whether we
return to user mdoe was a mess:

 - error_sti was misnamed.  In particular, it did not enable interrupts.

 - Error handling for gs_change was hopelessly tangled the normal
   usermode path.  Separate it out.  This saves a branch in normal
   entries from kernel mode.

 - The comments were bad.

Fix it up.  As a nice side effect, there's now a code path that
happens on error entries from user mode.  We'll use it soon.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/f1be898ab93360169fb845ab85185948832209ee.1433878454.git.luto@kernel.org
[ Prettified it, clarified comments some more. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-06-10 08:47:57 +02:00
Denys Vlasenko
a92fde2523 x86/asm/entry/32: Shorten __audit_syscall_entry() args preparation
We use three MOVs to swap edx and ecx. We can use one XCHG
instead.

Expand the comments. It's difficult to keep track which arg#
every register corresponds to, so spell it out.

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Drewry <wad@chromium.org>
Link: http://lkml.kernel.org/r/1433876051-26604-3-git-send-email-dvlasenk@redhat.com
[ Expanded the comments some more. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-06-10 08:42:13 +02:00
Denys Vlasenko
1536bb46fa x86/asm/entry/32: Explain reloading of registers after __audit_syscall_entry()
Here it is not obvious why we load pt_regs->cx to %esi etc.
Lets improve comments.

Explain that here we combine two things: first, we reload
registers since some of them are clobbered by the C function we
just called; and we also convert 32-bit syscall params to 64-bit
C ABI, because we are going to jump back to syscall dispatch
code.

Move reloading of 6th argument into the macro instead of having
it after each of two macro invocations.

No actual code changes here.

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Drewry <wad@chromium.org>
Link: http://lkml.kernel.org/r/1433876051-26604-2-git-send-email-dvlasenk@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-06-10 08:42:13 +02:00
Denys Vlasenko
aee4b013a7 x86/asm/entry/32: Fix fallout from the R9 trick removal in the SYSCALL code
I put %ebp restoration code too late. Under strace, it is not
reached and %ebp is not restored upon return to userspace.

This is the fix. Run-tested.

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Drewry <wad@chromium.org>
Link: http://lkml.kernel.org/r/1433876051-26604-1-git-send-email-dvlasenk@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-06-10 08:42:12 +02:00
Denys Vlasenko
9b47feb708 x86/asm/entry: Clean up entry*.S style, final bits
A few bits were missed.

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-06-09 11:48:24 +02:00
Ingo Molnar
bace7117d3 x86/asm/entry: (Re-)rename __NR_entry_INT80_compat_max to __NR_syscall_compat_max
Brian Gerst noticed that I did a weird rename in the following commit:

   b2502b418e ("x86/asm/entry: Untangle 'system_call' into two entry points: entry_SYSCALL_64 and entry_INT80_32")

which renamed __NR_ia32_syscall_max to __NR_entry_INT80_compat_max.

Now the original name was a misnomer, but the new one is a misnomer as well,
as all the 32-bit compat syscall entry points (sysenter, syscall) share the
system call table, not just the INT80 based one.

Rename it to __NR_syscall_compat_max.

Reported-by: Brian Gerst <brgerst@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-06-08 23:43:38 +02:00
Denys Vlasenko
eb47854415 x86/asm/entry/32: Reinstate clearing of pt_regs->r8..r11 on EFAULT path
I broke this recently when I changed pt_regs->r8..r11 clearing
logic in INT 80 code path.

There is a branch from SYSENTER/SYSCALL code to INT 80 code:
if we fail to retrieve arg6, we return EFAULT. Before this
patch, in this case we don't clear pt_regs->r8..r11.

This patch fixes this. The resulting code is smaller and
simpler.

While at it, remove incorrect comment about syscall dispatching
CALL insn: it does not use RIP-relative addressing form (the
comment was meant to be "TODO: make this rip-relative", and
morphed since then, dropping "TODO").

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Drewry <wad@chromium.org>
Link: http://lkml.kernel.org/r/1433701470-28800-1-git-send-email-dvlasenk@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-06-08 23:43:37 +02:00
Ingo Molnar
4d7321381e x86/asm/entry/64: Clean up entry_64.S
Make the 64-bit syscall entry code a bit more readable:

 - use consistent assembly coding style similar to the other entry_*.S files

 - remove old comments that are not true anymore

 - eliminate whitespace noise

 - use consistent vertical spacing

 - fix various comments

 - reorganize entry point generation tables to be more readable

No code changed:

  # arch/x86/entry/entry_64.o:

   text    data     bss     dec     hex filename
  12282       0       0   12282    2ffa entry_64.o.before
  12282       0       0   12282    2ffa entry_64.o.after

md5:
   cbab1f2d727a2a8a87618eeb79f391b7  entry_64.o.before.asm
   cbab1f2d727a2a8a87618eeb79f391b7  entry_64.o.after.asm

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-06-08 20:48:43 +02:00
Ingo Molnar
9dda1658a9 Merge branch 'x86/asm' into x86/core, to prepare for new patch
Collect all changes to arch/x86/entry/entry_64.S, before applying
patch that changes most of the file.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-06-08 20:48:20 +02:00
Ingo Molnar
a49976d14f x86/asm/entry/32: Clean up entry_32.S
Make the 32-bit syscall entry code a bit more readable:

 - use consistent assembly coding style similar to entry_64.S

 - remove old comments that are not true anymore

 - eliminate whitespace noise

 - use consistent vertical spacing

 - fix various comments

No code changed:

  # arch/x86/entry/entry_32.o:

   text    data     bss     dec     hex filename
   6025       0       0    6025    1789 entry_32.o.before
   6025       0       0    6025    1789 entry_32.o.after

md5:
   f3fa16b2b0dca804f052deb6b30ba6cb  entry_32.o.before.asm
   f3fa16b2b0dca804f052deb6b30ba6cb  entry_32.o.after.asm

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-06-08 09:54:24 +02:00
Ingo Molnar
b2502b418e x86/asm/entry: Untangle 'system_call' into two entry points: entry_SYSCALL_64 and entry_INT80_32
The 'system_call' entry points differ starkly between native 32-bit and 64-bit
kernels: on 32-bit kernels it defines the INT 0x80 entry point, while on
64-bit it's the SYSCALL entry point.

This is pretty confusing when looking at generic code, and it also obscures
the nature of the entry point at the assembly level.

So unangle this by splitting the name into its two uses:

	system_call (32) -> entry_INT80_32
	system_call (64) -> entry_SYSCALL_64

As per the generic naming scheme for x86 system call entry points:

	entry_MNEMONIC_qualifier

where 'qualifier' is one of _32, _64 or _compat.

Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-06-08 09:14:21 +02:00
Ingo Molnar
4c8cd0c50d x86/asm/entry: Untangle 'ia32_sysenter_target' into two entry points: entry_SYSENTER_32 and entry_SYSENTER_compat
So the SYSENTER instruction is pretty quirky and it has different behavior
depending on bitness and CPU maker.

Yet we create a false sense of coherency by naming it 'ia32_sysenter_target'
in both of the cases.

Split the name into its two uses:

	ia32_sysenter_target (32)    -> entry_SYSENTER_32
	ia32_sysenter_target (64)    -> entry_SYSENTER_compat

As per the generic naming scheme for x86 system call entry points:

	entry_MNEMONIC_qualifier

where 'qualifier' is one of _32, _64 or _compat.

Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-06-08 08:47:46 +02:00
Ingo Molnar
2cd23553b4 x86/asm/entry: Rename compat syscall entry points
Rename the following system call entry points:

	ia32_cstar_target       -> entry_SYSCALL_compat
	ia32_syscall            -> entry_INT80_compat

The generic naming scheme for x86 system call entry points is:

	entry_MNEMONIC_qualifier

where 'qualifier' is one of _32, _64 or _compat.

Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-06-08 08:47:36 +02:00
Ingo Molnar
138bd56a21 x86/asm/entry/64/compat: Rename ia32entry.S -> entry_64_compat.S
So we now have the following system entry code related
files, which define the following system call instruction
and other entry paths:

   entry_32.S            # 32-bit binaries on 32-bit kernels
   entry_64.S            # 64-bit binaries on 64-bit kernels
   entry_64_compat.S	 # 32-bit binaries on 64-bit kernels

Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Drewry <wad@chromium.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-06-07 14:56:50 +02:00
Denys Vlasenko
7a5a9824c1 x86/asm/entry/32: Remove unnecessary optimization in stub32_clone
Really swap arguments #4 and #5 in stub32_clone instead of
"optimizing" it into a move.

Yes, tls_val is currently unused. Yes, on some CPUs XCHG is a
little bit more expensive than MOV. But a cycle or two on an
expensive syscall like clone() is way below noise floor, and
this optimization is simply not worth the obfuscation of logic.

[ There's also ongoing work on the clone() ABI by Josh Triplett
  that will depend on this change later on. ]

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Drewry <wad@chromium.org>
Link: http://lkml.kernel.org/r/1433339930-20880-2-git-send-email-dvlasenk@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-06-05 13:41:28 +02:00
Denys Vlasenko
5cdc683b7d x86/asm/entry/32: Explain the stub32_clone logic
The reason for copying of %r8 to %rcx is quite non-obvious.
Add a comment which explains why it is done.

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Drewry <wad@chromium.org>
Link: http://lkml.kernel.org/r/1433339930-20880-1-git-send-email-dvlasenk@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-06-05 13:41:27 +02:00
Ingo Molnar
54ad726c51 x86/asm/entry/32: Improve code readability
Make the 64-bit compat 32-bit syscall entry code a bit more readable:

 - eliminate whitespace noise

 - use consistent vertical spacing

 - use consistent assembly coding style similar to entry_64.S

 - fix various comments

No code changed:

arch/x86/entry/ia32entry.o:

   text	   data	    bss	    dec	    hex	filename
   1391	      0	      0	   1391	    56f	ia32entry.o.before
   1391	      0	      0	   1391	    56f	ia32entry.o.after

md5:
   f28501dcc366e68b557313942c6496d6  ia32entry.o.before.asm
   f28501dcc366e68b557313942c6496d6  ia32entry.o.after.asm

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-06-05 13:22:22 +02:00
Denys Vlasenko
53e9accf0f x86/asm/entry/32: Do not use R9 in SYSCALL32 entry point
SYSENTER and SYSCALL 32-bit entry points differ in handling of
arg2 and arg6.

SYSENTER:
 * ecx  arg2
 * ebp  user stack
 * 0(%ebp) arg6

SYSCALL:
 * ebp  arg2
 * esp  user stack
 * 0(%esp) arg6

Sysenter code loads 0(%ebp) to %ebp right away.
(This destroys %ebp. It means we do not preserve it on return.
It's not causing problems since userspace VDSO code does not
depend on it, and SYSENTER insn can't be sanely used outside of
VDSO).

Syscall code loads 0(%ebp) to %r9. This allows to eliminate one
MOV insn (r9 is a register where arg6 should be for 64-bit ABI),
but on audit/ptrace code paths this requires juggling of r9 and
ebp: (1) ptrace expects arg6 to be in pt_regs->bp;
(2) r9 is callee-clobbered register and needs to be
saved/restored     around calls to C functions.

This patch changes syscall code to load 0(%ebp) to %ebp, making
it more similar to sysenter code. It's a bit smaller:

   text    data     bss     dec     hex filename
   1407       0       0    1407     57f ia32entry.o.before
   1391       0       0    1391     56f ia32entry.o

To preserve ABI compat, we restore ebp on exit.

Run-tested.

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Drewry <wad@chromium.org>
Link: http://lkml.kernel.org/r/1433336169-18964-1-git-send-email-dvlasenk@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-06-05 13:22:22 +02:00
Denys Vlasenko
73cbf68791 x86/asm/entry/32: Open-code LOAD_ARGS32
This macro is small, has only three callsites, and one of them
is slightly different using a conditional parameter.

A few saved lines aren't worth the resulting obfuscation.

Generated machine code is identical.

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Drewry <wad@chromium.org>
Link: http://lkml.kernel.org/r/1433271842-9139-2-git-send-email-dvlasenk@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-06-05 13:22:22 +02:00
Denys Vlasenko
ef0cd5dc25 x86/asm/entry/32: Open-code CLEAR_RREGS
This macro is small, has only four callsites, and one of them is
slightly different using a conditional parameter.

A few saved lines aren't worth the resulting obfuscation.

Generated machine code is identical.

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
[ Added comments. ]
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Drewry <wad@chromium.org>
Link: http://lkml.kernel.org/r/1433271842-9139-1-git-send-email-dvlasenk@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-06-05 13:22:22 +02:00
Denys Vlasenko
61b1e3e782 x86/asm/entry/32: Simplify the zeroing of pt_regs->r8..r11 in the int80 code path
32-bit syscall entry points do not save the complete pt_regs struct,
they leave some fields uninitialized. However, they must be
careful to not leak uninitialized data in pt_regs->r8..r11 to
ptrace users.

CLEAR_RREGS macro is used to zero these fields out when needed.

However, in the int80 code path this zeroing is unconditional.
This patch simplifies it by storing zeroes there right away,
when pt_regs is constructed on stack.

This uses shorter instructions:

   text    data     bss     dec     hex filename
   1423       0       0    1423     58f ia32entry.o.before
   1407       0       0    1407     57f ia32entry.o

Compile-tested.

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Drewry <wad@chromium.org>
Link: http://lkml.kernel.org/r/1433266510-2938-1-git-send-email-dvlasenk@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-06-05 13:22:21 +02:00
Andy Lutomirski
5ca6f70f38 x86/asm/entry/64: Remove pointless jump to irq_return
INTERRUPT_RETURN turns into a jmp instruction.  There's no need
for extra indirection.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: <linux-kernel@vger.kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/2f2318653dbad284a59311f13f08cea71298fd7c.1433449436.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-06-05 12:42:41 +02:00
Ingo Molnar
00398a0018 x86/asm/entry: Move the vsyscall code to arch/x86/entry/vsyscall/
The vsyscall code is entry code too, so move it to arch/x86/entry/vsyscall/.

Cc: Borislav Petkov <bp@alien8.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-06-04 07:37:37 +02:00
Ingo Molnar
1f57d5d85b x86/asm/entry: Move the arch/x86/syscalls/ definitions to arch/x86/entry/syscalls/
The build time generated syscall definitions are entry code related, move
them into the arch/x86/entry/ directory.

Cc: Borislav Petkov <bp@alien8.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-06-04 07:37:37 +02:00
Ingo Molnar
d36f947904 x86/asm/entry: Move arch/x86/include/asm/calling.h to arch/x86/entry/
asm/calling.h is private to the entry code, make this more apparent
by moving it to the new arch/x86/entry/ directory.

Cc: Borislav Petkov <bp@alien8.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-06-04 07:37:36 +02:00
Ingo Molnar
e6b93f4e48 x86/asm/entry: Move the 'thunk' functions to arch/x86/entry/
These are all calling x86 entry code functions, so move them close
to other entry code.

Change lib-y to obj-y: there's no real difference between the two
as we don't really drop any of them during the linking stage, and
obj-y is the more common approach for core kernel object code.

Cc: Borislav Petkov <bp@alien8.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-06-04 07:37:33 +02:00
Ingo Molnar
d603c8e184 x86/asm/entry, x86/vdso: Move the vDSO code to arch/x86/entry/vdso/
Cc: Borislav Petkov <bp@alien8.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-06-03 18:51:37 +02:00
Ingo Molnar
19a433f451 x86/asm/entry: Move the compat syscall entry code to arch/x86/entry/
Move the ia32entry.S file over into arch/x86/entry/.

Cc: Borislav Petkov <bp@alien8.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-06-03 18:51:32 +02:00
Ingo Molnar
905a36a285 x86/asm/entry: Move entry_64.S and entry_32.S to arch/x86/entry/
Create a new directory hierarchy for the low level x86 entry code:

    arch/x86/entry/*

This will host all the low level glue that is currently scattered
all across arch/x86/.

Start with entry_64.S and entry_32.S.

Cc: Borislav Petkov <bp@alien8.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-06-03 18:51:28 +02:00