This is the first in a series of MPX tracing patches.
I've found these extremely useful in the process of
debugging applications and the kernel code itself.
This exception hooks in to the bounds (#BR) exception
very early and allows capturing the key registers which
would influence how the exception is handled.
Note that bndcfgu/bndstatus are technically still
64-bit registers even in 32-bit mode.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Hansen <dave@sr71.net>
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/20150607183703.5FE2619A@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The MPX code can only work on the current task. You can not,
for instance, enable MPX management in another process or
thread. You can also not handle a fault for another process or
thread.
Despite this, we pass a task_struct around prolifically. This
patch removes all of the task struct passing for code paths
where the code can not deal with another task (which turns out
to be all of them).
This has no functional changes. It's just a cleanup.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Hansen <dave@sr71.net>
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: bp@alien8.de
Link: http://lkml.kernel.org/r/20150607183702.6A81DA2C@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The MPX registers (bndcsr/bndcfgu/bndstatus) are not directly
accessible via normal instructions. They essentially act as
if they were floating point registers and are saved/restored
along with those registers.
There are two main paths in the MPX code where we care about
the contents of these registers:
1. #BR (bounds) faults
2. the prctl() code where we are setting MPX up
Both of those paths _might_ be called without the FPU having
been used. That means that 'tsk->thread.fpu.state' might
never be allocated.
Also, fpu_save_init() is not preempt-safe. It was a bug to
call it without disabling preemption. The new
get_xsave_addr() calls unlazy_fpu() instead and properly
disables preemption.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dave Hansen <dave@sr71.net>
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: Rik van Riel <riel@redhat.com>
Cc: Suresh Siddha <sbsiddha@gmail.com>
Cc: bp@alien8.de
Link: http://lkml.kernel.org/r/20150607183701.BC0D37CF@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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>
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>
This cleans up the call sites and the function a bit,
and also makes it more symmetric with the other high
level FPU state handling functions.
It's still only valid for the current task, as we copy
to the FPU registers of the current CPU.
No change in functionality.
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: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Factor out the FPU error code handling code from traps.c and fpu/internal.h
and move them close to each other.
Also convert the helper functions to 'struct fpu *', which further simplifies
them.
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: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
So 6 years ago we made the FPU fpstate dynamically allocated:
aa283f4927 ("x86, fpu: lazy allocation of FPU area - v5")
61c4628b53 ("x86, fpu: split FPU state from task struct - v5")
In hindsight this was a mistake:
- it complicated context allocation failure handling, such as:
/* kthread execs. TODO: cleanup this horror. */
if (WARN_ON(fpstate_alloc_init(fpu)))
force_sig(SIGKILL, tsk);
- it caused us to enable irqs in fpu__restore():
local_irq_enable();
/*
* does a slab alloc which can sleep
*/
if (fpstate_alloc_init(fpu)) {
/*
* ran out of memory!
*/
do_group_exit(SIGKILL);
return;
}
local_irq_disable();
- it (slightly) slowed down task creation/destruction by adding
slab allocation/free pattens.
- it made access to context contents (slightly) slower by adding
one more pointer dereference.
The motivation for the dynamic allocation was two-fold:
- reduce memory consumption by non-FPU tasks
- allocate and handle only the necessary amount of context for
various XSAVE processors that have varying hardware frame
sizes.
These days, with glibc using SSE memcpy by default and GCC optimizing
for SSE/AVX by default, the scope of FPU using apps on an x86 system is
much larger than it was 6 years ago.
For example on a freshly installed Fedora 21 desktop system, with a
recent kernel, all non-kthread tasks have used the FPU shortly after
bootup.
Also, even modern embedded x86 CPUs try to support the latest vector
instruction set - so they'll too often use the larger xstate frame
sizes.
So remove the dynamic allocation complication by embedding the FPU
fpstate in task_struct again. This should make the FPU a lot more
accessible to all sorts of atomic contexts.
We could still optimize for the xstate frame size in the future,
by moving the state structure to the last element of task_struct,
and allocating only a part of that.
This change is kept minimal by still keeping the ctx_alloc()/free()
routines (that now do nothing substantial) - we'll remove them in
the following patches.
Reviewed-by: Borislav Petkov <bp@alien8.de>
Cc: Andy Lutomirski <luto@amacapital.net>
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: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
So fpu_save_init() is a historic name that got its name when the only
way the FPU state was FNSAVE, which cleared (well, destroyed) the FPU
state after saving it.
Nowadays the name is misleading, because ever since the introduction of
FXSAVE (and more modern FPU saving instructions) the 'we need to reload
the FPU state' part is only true if there's a pending FPU exception [*],
which is almost never the case.
So rename it to copy_fpregs_to_fpstate() to make it clear what's
happening. Also add a few comments about why we cannot keep registers
in certain cases.
Also clean up the control flow a bit, to make it more apparent when
we are dropping/keeping FP registers, and to optimize the common
case (of keeping fpregs) some more.
[*] Probably not true anymore, modern instructions always leave the FPU
state intact, even if exceptions are pending: because pending FP
exceptions are posted on the next FP instruction, not asynchronously.
They were truly asynchronous back in the IRQ13 case, and we had to
synchronize with them, but that code is not working anymore: we don't
have IRQ13 mapped in the IDT anymore.
But a cleanup patch is obviously not the place to change subtle behavior.
Reviewed-by: Borislav Petkov <bp@alien8.de>
Cc: Andy Lutomirski <luto@amacapital.net>
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: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This unifies all the FPU related header files under a unified, hiearchical
naming scheme:
- asm/fpu/types.h: FPU related data types, needed for 'struct task_struct',
widely included in almost all kernel code, and hence kept
as small as possible.
- asm/fpu/api.h: FPU related 'public' methods exported to other subsystems.
- asm/fpu/internal.h: FPU subsystem internal methods
- asm/fpu/xsave.h: XSAVE support internal methods
(Also standardize the header guard in asm/fpu/internal.h.)
Reviewed-by: Borislav Petkov <bp@alien8.de>
Cc: Andy Lutomirski <luto@amacapital.net>
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: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Migrate this function to pure 'struct fpu' usage.
Reviewed-by: Borislav Petkov <bp@alien8.de>
Cc: Andy Lutomirski <luto@amacapital.net>
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: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
It's another piece of FPU internals that is better off close to
the other FPU internals.
Reviewed-by: Borislav Petkov <bp@alien8.de>
Cc: Andy Lutomirski <luto@amacapital.net>
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: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Fix a minor header file dependency bug in asm/fpu-internal.h: it
relies on i387.h but does not include it. All users of fpu-internal.h
included it explicitly.
Also remove unnecessary includes, to reduce compilation time.
This also makes it easier to use it as a standalone header file
for FPU internals, such as an upcoming C module in arch/x86/kernel/fpu/.
Reviewed-by: Borislav Petkov <bp@alien8.de>
Cc: Andy Lutomirski <luto@amacapital.net>
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: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This field is kept separate from the main FPU state structure for
no good reason.
Reviewed-by: Borislav Petkov <bp@alien8.de>
Cc: Andy Lutomirski <luto@amacapital.net>
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: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Most init_fpu() users don't want the register-saving aspect of the
function, they are calling it for 'current' and when FPU registers
are not allocated and initialized yet.
Split out a simplified API that does just that (and add debug-checks
for these conditions): fpstate_alloc_init().
Use it where appropriate.
Reviewed-by: Borislav Petkov <bp@alien8.de>
Cc: Andy Lutomirski <luto@amacapital.net>
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: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This function is a misnomer on two levels:
1) it doesn't really manipulate TS on modern CPUs anymore, its
primary purpose is to save FPU state, used:
- when executing fork()/clone(): to copy current FPU state
to the child's FPU state.
- when handling math exceptions: to generate the math error
si_code in the signal frame.
2) even on legacy CPUs it doesn't actually 'unlazy', if then
it lazies the FPU state: as a side effect of the old FNSAVE
instruction which clears (destroys) FPU state it's necessary
to set CR0::TS.
So rename it to fpu__save() to better reflect its purpose.
Reviewed-by: Borislav Petkov <bp@alien8.de>
Cc: Andy Lutomirski <luto@amacapital.net>
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: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Use IA32_SYSCALL_VECTOR for both compat and native.
Signed-off-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>
Link: http://lkml.kernel.org/r/1431185813-15413-4-git-send-email-brgerst@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Those were leftovers of the x86 merge, see
081f75bbdc ("traps: x86: make traps_32.c and traps_64.c equal")
for example and are not needed now.
Signed-off-by: Borislav Petkov <bp@suse.de>
Deferred errors indicate error conditions that were not corrected, but
require no action from S/W (or action is optional).These errors provide
info about a latent UC MCE that can occur when a poisoned data is
consumed by the processor.
Processors that report these errors can be configured to generate APIC
interrupts to notify OS about the error.
Provide an interrupt handler in this patch so that OS can catch these
errors as and when they happen. Currently, we simply log the errors and
exit the handler as S/W action is not mandated.
Signed-off-by: Aravind Gopalakrishnan <Aravind.Gopalakrishnan@amd.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: x86-ml <x86@kernel.org>
Cc: linux-edac <linux-edac@vger.kernel.org>
Link: http://lkml.kernel.org/r/1430913538-1415-5-git-send-email-Aravind.Gopalakrishnan@amd.com
Signed-off-by: Borislav Petkov <bp@suse.de>
Pull NOHZ changes from Ingo Molnar:
"This tree adds full dynticks support to KVM guests (support the
disabling of the timer tick on the guest). The main missing piece was
the recognition of guest execution as RCU extended quiescent state and
related changes"
* 'timers-nohz-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
kvm,rcu,nohz: use RCU extended quiescent state when running KVM guest
context_tracking: Export context_tracking_user_enter/exit
context_tracking: Run vtime_user_enter/exit only when state == CONTEXT_USER
context_tracking: Add stub context_tracking_is_enabled
context_tracking: Generalize context tracking APIs to support user and guest
context_tracking: Rename context symbols to prepare for transition state
ppc: Remove unused cpp symbols in kvm headers
Pull x86 fpu changes from Ingo Molnar:
"Various x86 FPU handling cleanups, refactorings and fixes (Borislav
Petkov, Oleg Nesterov, Rik van Riel)"
* 'x86-fpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (21 commits)
x86/fpu: Kill eager_fpu_init_bp()
x86/fpu: Don't allocate fpu->state for swapper/0
x86/fpu: Rename drop_init_fpu() to fpu_reset_state()
x86/fpu: Fold __drop_fpu() into its sole user
x86/fpu: Don't abuse drop_init_fpu() in flush_thread()
x86/fpu: Use restore_init_xstate() instead of math_state_restore() on kthread exec
x86/fpu: Introduce restore_init_xstate()
x86/fpu: Document user_fpu_begin()
x86/fpu: Factor out memset(xstate, 0) in fpu_finit() paths
x86/fpu: Change xstateregs_get()/set() to use ->xsave.i387 rather than ->fxsave
x86/fpu: Don't abuse FPU in kernel threads if use_eager_fpu()
x86/fpu: Always allow FPU in interrupt if use_eager_fpu()
x86/fpu: __kernel_fpu_begin() should clear fpu_owner_task even if use_eager_fpu()
x86/fpu: Also check fpu_lazy_restore() when use_eager_fpu()
x86/fpu: Use task_disable_lazy_fpu_restore() helper
x86/fpu: Use an explicit if/else in switch_fpu_prepare()
x86/fpu: Introduce task_disable_lazy_fpu_restore() helper
x86/fpu: Move lazy restore functions up a few lines
x86/fpu: Change math_error() to use unlazy_fpu(), kill (now) unused save_init_fpu()
x86/fpu: Don't do __thread_fpu_end() if use_eager_fpu()
...
user_mode_ignore_vm86() can be used instead of user_mode(), in
places where we have already done a v8086_mode() security
check of ptregs.
But doing this check in the wrong place would be a bug that
could result in security problems, and also the naming still
isn't very clear.
Furthermore, it only affects 32-bit kernels, while most
development happens on 64-bit kernels.
If we replace them with user_mode() checks then the cost is only
a very minor increase in various slowpaths:
text data bss dec hex filename
10573391 703562 1753042 13029995 c6d26b vmlinux.o.before
10573423 703562 1753042 13030027 c6d28b vmlinux.o.after
So lets get rid of this distinction once and for all.
Acked-by: Borislav Petkov <bp@suse.de>
Acked-by: Andy Lutomirski <luto@kernel.org>
Cc: Andrew Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brad Spengler <spender@grsecurity.net>
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: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20150329090233.GA1963@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This allows us to remove some unnecessary ifdefs. There should
be no change to the generated code.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brad Spengler <spender@grsecurity.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/f7e00f0d668e253abf0bd8bf36491ac47bd761ff.1426728647.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
user_mode_vm() and user_mode() are now the same. Change all callers
of user_mode_vm() to user_mode().
The next patch will remove the definition of user_mode_vm.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brad Spengler <spender@grsecurity.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/43b1f57f3df70df5a08b0925897c660725015554.1426728647.git.luto@kernel.org
[ Merged to a more recent kernel. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
A few of the user_mode() checks in traps.c are immediately after
explicit checks for vm86 mode. Change them to user_mode_ignore_vm86().
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brad Spengler <spender@grsecurity.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/0b324d5b75c3402be07f8d3c6245ed7f4995029e.1426728647.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Call it what it does and in accordance with the context where it is
used: we reset the FPU state either because we were unable to restore it
from the one saved in the task or because we simply want to reset it.
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The one in do_debug() is probably harmless, but better safe than sorry.
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Cc: <stable@vger.kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/d67deaa9df5458363623001f252d1aee3215d014.1425948056.git.luto@amacapital.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Current context tracking symbols are designed to express living state.
As such they are prefixed with "IN_": IN_USER, IN_KERNEL.
Now we are going to use these symbols to also express state transitions
such as context_tracking_enter(IN_USER) or context_tracking_exit(IN_USER).
But while the "IN_" prefix works well to express entering a context, it's
confusing to depict a context exit: context_tracking_exit(IN_USER)
could mean two things:
1) We are exiting the current context to enter user context.
2) We are exiting the user context
We want 2) but the reviewer may be confused and understand 1)
So lets disambiguate these symbols and rename them to CONTEXT_USER and
CONTEXT_KERNEL.
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Will deacon <will.deacon@arm.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
I broke 32-bit kernels. The implementation of sp0 was correct
as far as I can tell, but sp0 was much weirder on x86_32 than I
realized. It has the following issues:
- Init's sp0 is inconsistent with everything else's: non-init tasks
are offset by 8 bytes. (I have no idea why, and the comment is unhelpful.)
- vm86 does crazy things to sp0.
Fix it up by replacing this_cpu_sp0() with
current_top_of_stack() and using a new percpu variable to track
the top of the stack on x86_32.
Signed-off-by: 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: Thomas Gleixner <tglx@linutronix.de>
Fixes: 75182b1632 ("x86/asm/entry: Switch all C consumers of kernel_stack to this_cpu_sp0()")
Link: http://lkml.kernel.org/r/d09dbe270883433776e0cbee3c7079433349e96d.1425692936.git.luto@amacapital.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This will make modifying the semantics of kernel_stack easier.
The change to ist_begin_non_atomic() is necessary because sp0 no
longer points to the same THREAD_SIZE-aligned region as RSP;
it's one byte too high for that. At Denys' suggestion, rather
than offsetting it, just check explicitly that we're in the
correct range ending at sp0. This has the added benefit that we
no longer assume that the thread stack is aligned to
THREAD_SIZE.
Suggested-by: Denys Vlasenko <dvlasenk@redhat.com>
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/ef8254ad414cbb8034c9a56396eeb24f5dd5b0de.1425611534.git.luto@amacapital.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
As early_trap_init() doesn't use IST, replace
set_intr_gate_ist() and set_system_intr_gate_ist() with their
standard counterparts.
set_intr_gate() requires a trace_debug symbol which we don't
have and won't use. This patch separates set_intr_gate() into two
parts, and uses base version in early_trap_init().
Reported-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Acked-by: Andy Lutomirski <luto@amacapital.net>
Cc: <dave.hansen@linux.intel.com>
Cc: <lizefan@huawei.com>
Cc: <masami.hiramatsu.pt@hitachi.com>
Cc: <oleg@redhat.com>
Cc: <rostedt@goodmis.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1425010789-13714-1-git-send-email-wangnan0@huawei.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Before this patch early_trap_init() installs DEBUG_STACK for
X86_TRAP_BP and X86_TRAP_DB. However, DEBUG_STACK doesn't work
correctly until cpu_init() <-- trap_init().
This patch passes 0 to set_intr_gate_ist() and
set_system_intr_gate_ist() instead of DEBUG_STACK to let it use
same stack as kernel, and installs DEBUG_STACK for them in
trap_init().
As core runs at ring 0 between early_trap_init() and
trap_init(), there is no chance to get a bad stack before
trap_init().
As NMI is also enabled in trap_init(), we don't need to care
about is_debug_stack() and related things used in
arch/x86/kernel/nmi.c.
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Cc: <dave.hansen@linux.intel.com>
Cc: <lizefan@huawei.com>
Cc: <luto@amacapital.net>
Cc: <oleg@redhat.com>
Link: http://lkml.kernel.org/r/1424929779-13174-1-git-send-email-wangnan0@huawei.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull FPU updates from Borislav Petkov:
"A round of updates to the FPU maze from Oleg and Rik. It should make
the code a bit more understandable/readable/streamlined and a preparation
for more cleanups and improvements in that area."
Signed-off-by: Ingo Molnar <mingo@kernel.org>
math_error() calls save_init_fpu() after conditional_sti(), this means
that the caller can be preempted. If !use_eager_fpu() we can hit the
WARN_ON_ONCE(!__thread_has_fpu(tsk)) and/or save the wrong FPU state.
Change math_error() to use unlazy_fpu() and kill save_init_fpu().
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Rik van Riel <riel@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1423252925-14451-4-git-send-email-riel@redhat.com
Signed-off-by: Borislav Petkov <bp@suse.de>
Pull x86 fpu updates from Ingo Molnar:
"Initial round of kernel_fpu_begin/end cleanups from Oleg Nesterov,
plus a cleanup from Borislav Petkov"
* 'x86-fpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86, fpu: Fix math_state_restore() race with kernel_fpu_begin()
x86, fpu: Don't abuse has_fpu in __kernel_fpu_begin/end()
x86, fpu: Introduce per-cpu in_kernel_fpu state
x86/fpu: Use a symbolic name for asm operand
context_tracking_user_exit() has no effect if in_interrupt() returns true,
so ist_enter() didn't work. Fix it by calling exception_enter(), and thus
context_tracking_user_exit(), before incrementing the preempt count.
This also adds an assertion that will catch the problem reliably if
CONFIG_PROVE_RCU=y to help prevent the bug from being reintroduced.
Link: http://lkml.kernel.org/r/261ebee6aee55a4724746d0d7024697013c40a08.1422709102.git.luto@amacapital.net
Fixes: 9592747538 x86, traps: Track entry into and exit from IST context
Reported-and-tested-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
math_state_restore() can race with kernel_fpu_begin() if irq comes
right after __thread_fpu_begin(), __save_init_fpu() will overwrite
fpu->state we are going to restore.
Add 2 simple helpers, kernel_fpu_disable() and kernel_fpu_enable()
which simply set/clear in_kernel_fpu, and change math_state_restore()
to exclude kernel_fpu_begin() in between.
Alternatively we could use local_irq_save/restore, but probably these
new helpers can have more users.
Perhaps they should disable/enable preemption themselves, in this case
we can remove preempt_disable() in __restore_xstate_sig().
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: matt.fleming@intel.com
Cc: bp@suse.de
Cc: pbonzini@redhat.com
Cc: luto@amacapital.net
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Suresh Siddha <sbsiddha@gmail.com>
Link: http://lkml.kernel.org/r/20150115192028.GD27332@redhat.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
In some IST handlers, if the interrupt came from user mode,
we can safely enable preemption. Add helpers to do it safely.
This is intended to be used my the memory failure code in
do_machine_check.
Acked-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
We currently pretend that IST context is like standard exception
context, but this is incorrect. IST entries from userspace are like
standard exceptions except that they use per-cpu stacks, so they are
atomic. IST entries from kernel space are like NMIs from RCU's
perspective -- they are not quiescent states even if they
interrupted the kernel during a quiescent state.
Add and use ist_enter and ist_exit to track IST context. Even
though x86_32 has no IST stacks, we track these interrupts the same
way.
This fixes two issues:
- Scheduling from an IST interrupt handler will now warn. It would
previously appear to work as long as we got lucky and nothing
overwrote the stack frame. (I don't know of any bugs in this
that would trigger the warning, but it's good to be on the safe
side.)
- RCU handling in IST context was dangerous. As far as I know,
only machine checks were likely to trigger this, but it's good to
be on the safe side.
Note that the machine check handlers appears to have been missing
any context tracking at all before this patch.
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
This causes all non-NMI, non-double-fault kernel entries from
userspace to run on the normal kernel stack. Double-fault is
exempt to minimize confusion if we double-fault directly from
userspace due to a bad kernel stack.
This is, suprisingly, simpler and shorter than the current code. It
removes the IMO rather frightening paranoid_userspace path, and it
make sync_regs much simpler.
There is no risk of stack overflow due to this change -- the kernel
stack that we switch to is empty.
This will also enable us to create non-atomic sections within
machine checks from userspace, which will simplify memory failure
handling. It will also allow the upcoming fsgsbase code to be
simplified, because it doesn't need to worry about usergs when
scheduling in paranoid_exit, as that code no longer exists.
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Tony Luck <tony.luck@intel.com>
Acked-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Pull x86 MPX fixes from Thomas Gleixner:
"Three updates for the new MPX infrastructure:
- Use the proper error check in the trap handler
- Add a proper config option for it
- Bring documentation up to date"
* 'x86-mpx-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86, mpx: Give MPX a real config option prompt
x86, mpx: Update documentation
x86_64/traps: Fix always true condition
Pull x86 MPX support from Thomas Gleixner:
"This enables support for x86 MPX.
MPX is a new debug feature for bound checking in user space. It
requires kernel support to handle the bound tables and decode the
bound violating instruction in the trap handler"
* 'x86-mpx-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
asm-generic: Remove asm-generic arch_bprm_mm_init()
mm: Make arch_unmap()/bprm_mm_init() available to all architectures
x86: Cleanly separate use of asm-generic/mm_hooks.h
x86 mpx: Change return type of get_reg_offset()
fs: Do not include mpx.h in exec.c
x86, mpx: Add documentation on Intel MPX
x86, mpx: Cleanup unused bound tables
x86, mpx: On-demand kernel allocation of bounds tables
x86, mpx: Decode MPX instruction to get bound violation information
x86, mpx: Add MPX-specific mmap interface
x86, mpx: Introduce VM_MPX to indicate that a VMA is MPX specific
x86, mpx: Add MPX to disabled features
ia64: Sync struct siginfo with general version
mips: Sync struct siginfo with general version
mpx: Extend siginfo structure to include bound violation information
x86, mpx: Rename cfg_reg_u and status_reg
x86: mpx: Give bndX registers actual names
x86: Remove arbitrary instruction size limit in instruction decoder
These functions can be executed on the int3 stack, so kprobes
are dangerous. Tracing is probably a bad idea, too.
Fixes: b645af2d59 ("x86_64, traps: Rework bad_iret")
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Cc: <stable@vger.kernel.org> # Backport as far back as it would apply
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/50e33d26adca60816f3ba968875801652507d0c4.1416870125.git.luto@amacapital.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
It's possible for iretq to userspace to fail. This can happen because
of a bad CS, SS, or RIP.
Historically, we've handled it by fixing up an exception from iretq to
land at bad_iret, which pretends that the failed iret frame was really
the hardware part of #GP(0) from userspace. To make this work, there's
an extra fixup to fudge the gs base into a usable state.
This is suboptimal because it loses the original exception. It's also
buggy because there's no guarantee that we were on the kernel stack to
begin with. For example, if the failing iret happened on return from an
NMI, then we'll end up executing general_protection on the NMI stack.
This is bad for several reasons, the most immediate of which is that
general_protection, as a non-paranoid idtentry, will try to deliver
signals and/or schedule from the wrong stack.
This patch throws out bad_iret entirely. As a replacement, it augments
the existing swapgs fudge into a full-blown iret fixup, mostly written
in C. It's should be clearer and more correct.
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
On a 32-bit kernel, this has no effect, since there are no IST stacks.
On a 64-bit kernel, #SS can only happen in user code, on a failed iret
to user space, a canonical violation on access via RSP or RBP, or a
genuine stack segment violation in 32-bit kernel code. The first two
cases don't need IST, and the latter two cases are unlikely fatal bugs,
and promoting them to double faults would be fine.
This fixes a bug in which the espfix64 code mishandles a stack segment
violation.
This saves 4k of memory per CPU and a tiny bit of code.
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There's nothing special enough about the espfix64 double fault fixup to
justify writing it in assembly. Move it to C.
This also fixes a bug: if the double fault came from an IST stack, the
old asm code would return to a partially uninitialized stack frame.
Fixes: 3891a04aaf
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is really the meat of the MPX patch set. If there is one patch to
review in the entire series, this is the one. There is a new ABI here
and this kernel code also interacts with userspace memory in a
relatively unusual manner. (small FAQ below).
Long Description:
This patch adds two prctl() commands to provide enable or disable the
management of bounds tables in kernel, including on-demand kernel
allocation (See the patch "on-demand kernel allocation of bounds tables")
and cleanup (See the patch "cleanup unused bound tables"). Applications
do not strictly need the kernel to manage bounds tables and we expect
some applications to use MPX without taking advantage of this kernel
support. This means the kernel can not simply infer whether an application
needs bounds table management from the MPX registers. The prctl() is an
explicit signal from userspace.
PR_MPX_ENABLE_MANAGEMENT is meant to be a signal from userspace to
require kernel's help in managing bounds tables.
PR_MPX_DISABLE_MANAGEMENT is the opposite, meaning that userspace don't
want kernel's help any more. With PR_MPX_DISABLE_MANAGEMENT, the kernel
won't allocate and free bounds tables even if the CPU supports MPX.
PR_MPX_ENABLE_MANAGEMENT will fetch the base address of the bounds
directory out of a userspace register (bndcfgu) and then cache it into
a new field (->bd_addr) in the 'mm_struct'. PR_MPX_DISABLE_MANAGEMENT
will set "bd_addr" to an invalid address. Using this scheme, we can
use "bd_addr" to determine whether the management of bounds tables in
kernel is enabled.
Also, the only way to access that bndcfgu register is via an xsaves,
which can be expensive. Caching "bd_addr" like this also helps reduce
the cost of those xsaves when doing table cleanup at munmap() time.
Unfortunately, we can not apply this optimization to #BR fault time
because we need an xsave to get the value of BNDSTATUS.
==== Why does the hardware even have these Bounds Tables? ====
MPX only has 4 hardware registers for storing bounds information.
If MPX-enabled code needs more than these 4 registers, it needs to
spill them somewhere. It has two special instructions for this
which allow the bounds to be moved between the bounds registers
and some new "bounds tables".
They are similar conceptually to a page fault and will be raised by
the MPX hardware during both bounds violations or when the tables
are not present. This patch handles those #BR exceptions for
not-present tables by carving the space out of the normal processes
address space (essentially calling the new mmap() interface indroduced
earlier in this patch set.) and then pointing the bounds-directory
over to it.
The tables *need* to be accessed and controlled by userspace because
the instructions for moving bounds in and out of them are extremely
frequent. They potentially happen every time a register pointing to
memory is dereferenced. Any direct kernel involvement (like a syscall)
to access the tables would obviously destroy performance.
==== Why not do this in userspace? ====
This patch is obviously doing this allocation in the kernel.
However, MPX does not strictly *require* anything in the kernel.
It can theoretically be done completely from userspace. Here are
a few ways this *could* be done. I don't think any of them are
practical in the real-world, but here they are.
Q: Can virtual space simply be reserved for the bounds tables so
that we never have to allocate them?
A: As noted earlier, these tables are *HUGE*. An X-GB virtual
area needs 4*X GB of virtual space, plus 2GB for the bounds
directory. If we were to preallocate them for the 128TB of
user virtual address space, we would need to reserve 512TB+2GB,
which is larger than the entire virtual address space today.
This means they can not be reserved ahead of time. Also, a
single process's pre-popualated bounds directory consumes 2GB
of virtual *AND* physical memory. IOW, it's completely
infeasible to prepopulate bounds directories.
Q: Can we preallocate bounds table space at the same time memory
is allocated which might contain pointers that might eventually
need bounds tables?
A: This would work if we could hook the site of each and every
memory allocation syscall. This can be done for small,
constrained applications. But, it isn't practical at a larger
scale since a given app has no way of controlling how all the
parts of the app might allocate memory (think libraries). The
kernel is really the only place to intercept these calls.
Q: Could a bounds fault be handed to userspace and the tables
allocated there in a signal handler instead of in the kernel?
A: (thanks to tglx) mmap() is not on the list of safe async
handler functions and even if mmap() would work it still
requires locking or nasty tricks to keep track of the
allocation state there.
Having ruled out all of the userspace-only approaches for managing
bounds tables that we could think of, we create them on demand in
the kernel.
Based-on-patch-by: Qiaowei Ren <qiaowei.ren@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: linux-mm@kvack.org
Cc: linux-mips@linux-mips.org
Cc: Dave Hansen <dave@sr71.net>
Link: http://lkml.kernel.org/r/20141114151829.AD4310DE@viggo.jf.intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This essentially reverts commit:
ecd50f714c ("kprobes, x86: Call exception_enter after kprobes handled")
since it causes build errors with CONFIG_CONTEXT_TRACKING and
that has been made from misunderstandings;
context_track_user_*() don't involve much in interrupt context,
it just returns if in_interrupt() is true.
Instead of changing the do_debug/int3(), this just adds
context_track_user_*() to kprobes blacklist, since those are
still can be called right before kprobes handles int3 and debug
exceptions, and probing those will cause an infinite loop.
Reported-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Kees Cook <keescook@chromium.org>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Seiji Aguchi <seiji.aguchi@hds.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Kees Cook <keescook@chromium.org>
Link: http://lkml.kernel.org/r/20140614064711.7865.45957.stgit@kbuild-fedora.novalocal
Signed-off-by: Ingo Molnar <mingo@kernel.org>
If the probed insn triggers a trap, ->si_addr = regs->ip is technically
correct, but this is not what the signal handler wants; we need to pass
the address of the probed insn, not the address of xol slot.
Add the new arch-agnostic helper, uprobe_get_trap_addr(), and change
fill_trap_info() and math_error() to use it. !CONFIG_UPROBES case in
uprobes.h uses a macro to avoid include hell and ensure that it can be
compiled even if an architecture doesn't define instruction_pointer().
Test-case:
#include <signal.h>
#include <stdio.h>
#include <unistd.h>
extern void probe_div(void);
void sigh(int sig, siginfo_t *info, void *c)
{
int passed = (info->si_addr == probe_div);
printf(passed ? "PASS\n" : "FAIL\n");
_exit(!passed);
}
int main(void)
{
struct sigaction sa = {
.sa_sigaction = sigh,
.sa_flags = SA_SIGINFO,
};
sigaction(SIGFPE, &sa, NULL);
asm (
"xor %ecx,%ecx\n"
".globl probe_div; probe_div:\n"
"idiv %ecx\n"
);
return 0;
}
it fails if probe_div() is probed.
Note: show_unhandled_signals users should probably use this helper too,
but we need to cleanup them first.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Move the callsite of fill_trap_info() into do_error_trap() and remove
the "siginfo_t *info" argument.
This obviously breaks DO_ERROR() which passed info == NULL, we simply
change fill_trap_info() to return "siginfo_t *" and add the "default"
case which returns SEND_SIG_PRIV.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Extract the fill-siginfo code from DO_ERROR_INFO() into the new helper,
fill_trap_info().
It can calculate si_code and si_addr looking at trapnr, so we can remove
these arguments from DO_ERROR_INFO() and simplify the source code. The
generated code is the same, __builtin_constant_p(trapnr) == T.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Move the common code from DO_ERROR() and DO_ERROR_INFO() into the new
helper, do_error_trap(). This simplifies define's and shaves 527 bytes
from traps.o.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
force_sig() is just force_sig_info(SEND_SIG_PRIV). Imho it should die,
we have too many ugly "send signal" helpers.
And do_trap() looks just ugly because it uses force_sig_info() or
force_sig() depending on info != NULL.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
As requested by Linus add explicit __visible to the asmlinkage users.
This marks all functions visible to assembler.
Tree sweep for arch/x86/*
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Link: http://lkml.kernel.org/r/1398984278-29319-3-git-send-email-andi@firstfloor.org
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Use NOKPROBE_SYMBOL macro for protecting functions
from kprobes instead of __kprobes annotation under
arch/x86.
This applies nokprobe_inline annotation for some cases,
because NOKPROBE_SYMBOL() will inhibit inlining by
referring the symbol address.
This just folds a bunch of previous NOKPROBE_SYMBOL()
cleanup patches for x86 to one patch.
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Link: http://lkml.kernel.org/r/20140417081814.26341.51656.stgit@ltc230.yrl.intra.hitachi.co.jp
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Borislav Petkov <bp@suse.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fernando Luis Vázquez Cao <fernando_b1@lab.ntt.co.jp>
Cc: Gleb Natapov <gleb@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Jesper Nilsson <jesper.nilsson@axis.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Lebon <jlebon@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Matt Fleming <matt.fleming@intel.com>
Cc: Michel Lespinasse <walken@google.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Seiji Aguchi <seiji.aguchi@hds.com>
Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Move exception_enter() call after kprobes handler
is done. Since the exception_enter() involves
many other functions (like printk), it can cause
recursive int3/break loop when kprobes probe such
functions.
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Borislav Petkov <bp@suse.de>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Kees Cook <keescook@chromium.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Seiji Aguchi <seiji.aguchi@hds.com>
Link: http://lkml.kernel.org/r/20140417081740.26341.10894.stgit@ltc230.yrl.intra.hitachi.co.jp
Signed-off-by: Ingo Molnar <mingo@kernel.org>
To avoid a kernel crash by probing on lockdep code, call
kprobe_int3_handler() and kprobe_debug_handler()(which was
formerly called post_kprobe_handler()) directly from
do_int3 and do_debug.
Currently kprobes uses notify_die() to hook the int3/debug
exceptoins. Since there is a locking code in notify_die,
the lockdep code can be invoked. And because the lockdep
involves printk() related things, theoretically, we need to
prohibit probing on such code, which means much longer blacklist
we'll have. Instead, hooking the int3/debug for kprobes before
notify_die() can avoid this problem.
Anyway, most of the int3 handlers in the kernel are already
called from do_int3 directly, e.g. ftrace_int3_handler,
poke_int3_handler, kgdb_ll_trap. Actually only
kprobe_exceptions_notify is on the notifier_call_chain.
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Borislav Petkov <bp@suse.de>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Jonathan Lebon <jlebon@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Seiji Aguchi <seiji.aguchi@hds.com>
Link: http://lkml.kernel.org/r/20140417081733.26341.24423.stgit@ltc230.yrl.intra.hitachi.co.jp
Signed-off-by: Ingo Molnar <mingo@kernel.org>
So I was reading the exception handler generation code and got a real
headache looking at the unstructured mess that our DO_ERROR*()
generation code is today.
Make it more readable.
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Link: http://lkml.kernel.org/n/tip-kuabysiykvUJpgus35lhnhvs@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull x86/trace changes from Ingo Molnar:
"This adds page fault tracepoints which have zero runtime cost in the
disabled case via IDT trickery (no NOPs in the page fault hotpath)"
* 'x86-trace-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86, trace: Change user|kernel_page_fault to page_fault_user|kernel
x86, trace: Add page fault tracepoints
x86, trace: Delete __trace_alloc_intr_gate()
x86, trace: Register exception handler to trace IDT
x86, trace: Remove __alloc_intr_gate()
Only a couple of arches (sh/x86) use fpu_counter in task_struct so it can
be moved out into ARCH specific thread_struct, reducing the size of
task_struct for other arches.
Compile tested i386_defconfig + gcc 4.7.3
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Paul Mundt <paul.mundt@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch registers exception handlers for tracing to a trace IDT.
To implemented it in set_intr_gate(), this patch does followings.
- Register the exception handlers to
the trace IDT by prepending "trace_" to the handler's names.
- Also, newly introduce trace_page_fault() to add tracepoints
in a subsequent patch.
Signed-off-by: Seiji Aguchi <seiji.aguchi@hds.com>
Link: http://lkml.kernel.org/r/52716DEC.5050204@hds.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Rewrite the preempt_count macros in order to extract the 3 basic
preempt_count value modifiers:
__preempt_count_add()
__preempt_count_sub()
and the new:
__preempt_count_dec_and_test()
And since we're at it anyway, replace the unconventional
$op_preempt_count names with the more conventional preempt_count_$op.
Since these basic operators are equivalent to the previous _notrace()
variants, do away with the _notrace() versions.
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/n/tip-ewbpdbupy9xpsjhg960zwbv8@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
In fd4363fff3 ("x86: Introduce int3 (breakpoint)-based
instruction patching"), the mechanism that was introduced for
notifying alternatives code from int3 exception handler that and
exception occured was die_notifier.
This is however problematic, as early code might be using jump
labels even before the notifier registration has been performed,
which will then lead to an oops due to unhandled exception. One
of such occurences has been encountered by Fengguang:
int3: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
Modules linked in:
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 3.11.0-rc1-01429-g04bf576 #8
task: ffff88000da1b040 ti: ffff88000da1c000 task.ti: ffff88000da1c000
RIP: 0010:[<ffffffff811098cc>] [<ffffffff811098cc>] ttwu_do_wakeup+0x28/0x225
RSP: 0000:ffff88000dd03f10 EFLAGS: 00000006
RAX: 0000000000000000 RBX: ffff88000dd12940 RCX: ffffffff81769c40
RDX: 0000000000000002 RSI: 0000000000000000 RDI: 0000000000000001
RBP: ffff88000dd03f28 R08: ffffffff8176a8c0 R09: 0000000000000002
R10: ffffffff810ff484 R11: ffff88000dd129e8 R12: ffff88000dbc90c0
R13: ffff88000dbc90c0 R14: ffff88000da1dfd8 R15: ffff88000da1dfd8
FS: 0000000000000000(0000) GS:ffff88000dd00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: 00000000ffffffff CR3: 0000000001c88000 CR4: 00000000000006e0
Stack:
ffff88000dd12940 ffff88000dbc90c0 ffff88000da1dfd8 ffff88000dd03f48
ffffffff81109e2b ffff88000dd12940 0000000000000000 ffff88000dd03f68
ffffffff81109e9e 0000000000000000 0000000000012940 ffff88000dd03f98
Call Trace:
<IRQ>
[<ffffffff81109e2b>] ttwu_do_activate.constprop.56+0x6d/0x79
[<ffffffff81109e9e>] sched_ttwu_pending+0x67/0x84
[<ffffffff8110c845>] scheduler_ipi+0x15a/0x2b0
[<ffffffff8104dfb4>] smp_reschedule_interrupt+0x38/0x41
[<ffffffff8173bf5d>] reschedule_interrupt+0x6d/0x80
<EOI>
[<ffffffff810ff484>] ? __atomic_notifier_call_chain+0x5/0xc1
[<ffffffff8105cc30>] ? native_safe_halt+0xd/0x16
[<ffffffff81015f10>] default_idle+0x147/0x282
[<ffffffff81017026>] arch_cpu_idle+0x3d/0x5d
[<ffffffff81127d6a>] cpu_idle_loop+0x46d/0x5db
[<ffffffff81127f5c>] cpu_startup_entry+0x84/0x84
[<ffffffff8104f4f8>] start_secondary+0x3c8/0x3d5
[...]
Fix this by directly calling poke_int3_handler() from the int3
exception handler (analogically to what ftrace has been doing
already), instead of relying on notifier, registration of which
might not have yet been finalized by the time of the first trap.
Reported-and-tested-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: H. Peter Anvin <hpa@linux.intel.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/alpine.LNX.2.00.1307231007490.14024@pobox.suse.cz
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Since the IDT is referenced from a fixmap, make sure it is page aligned.
Merge with 32-bit one, since it was already aligned to deal with F00F
bug. Since bss is cleared before IDT setup, it can live there. This also
moves the other *_idt_table variables into common locations.
This avoids the risk of the IDT ever being moved in the bss and having
the mapping be offset, resulting in calling incorrect handlers. In the
current upstream kernel this is not a manifested bug, but heavily patched
kernels (such as those using the PaX patch series) did encounter this bug.
The tables other than idt_table technically do not need to be page
aligned, at least not at the current time, but using a common
declaration avoids mistakes. On 64 bits the table is exactly one page
long, anyway.
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: http://lkml.kernel.org/r/20130716183441.GA14232@www.outflux.net
Reported-by: PaX Team <pageexec@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Pull x86 tracing updates from Ingo Molnar:
"This tree adds IRQ vector tracepoints that are named after the handler
and which output the vector #, based on a zero-overhead approach that
relies on changing the IDT entries, by Seiji Aguchi.
The new tracepoints look like this:
# perf list | grep -i irq_vector
irq_vectors:local_timer_entry [Tracepoint event]
irq_vectors:local_timer_exit [Tracepoint event]
irq_vectors:reschedule_entry [Tracepoint event]
irq_vectors:reschedule_exit [Tracepoint event]
irq_vectors:spurious_apic_entry [Tracepoint event]
irq_vectors:spurious_apic_exit [Tracepoint event]
irq_vectors:error_apic_entry [Tracepoint event]
irq_vectors:error_apic_exit [Tracepoint event]
[...]"
* 'x86-tracing-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/tracing: Add config option checking to the definitions of mce handlers
trace,x86: Do not call local_irq_save() in load_current_idt()
trace,x86: Move creation of irq tracepoints from apic.c to irq.c
x86, trace: Add irq vector tracepoints
x86: Rename variables for debugging
x86, trace: Introduce entering/exiting_irq()
tracing: Add DEFINE_EVENT_FN() macro
Pull x86 debug update from Ingo Molnar:
"Misc debuggability improvements:
- Optimize the x86 CPU register printout a bit
- Expose the tboot TXT log via debugfs
- Small do_debug() cleanup"
* 'x86-debug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/tboot: Provide debugfs interfaces to access TXT log
x86: Remove weird PTR_ERR() in do_debug
x86/debug: Only print out DR registers if they are not power-on defaults
Rename variables for debugging to describe meaning of them precisely.
Also, introduce a generic way to switch IDT by checking a current state,
debug on/off.
Signed-off-by: Seiji Aguchi <seiji.aguchi@hds.com>
Link: http://lkml.kernel.org/r/51C323A8.7050905@hds.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
62edab905 changed the argument to notify_die() from dr6 to &dr6,
but weirdly, used PTR_ERR() to cast it to a long. Since dr6 is
on the stack, this is an abuse of PTR_ERR(). Cast to long, as
per kernel standard.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: K.Prasad <prasad@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/1371357768-4968-8-git-send-email-rusty@rustcorp.com.au
Signed-off-by: Ingo Molnar <mingo@kernel.org>
It is sometimes very helpful to be able to pinpoint the location which
causes a double fault before it turns into a triple fault and the
machine reboots. We have this for 32-bit already so extend it to 64-bit.
On 64-bit we get the register snapshot at #DF time and not from the
first exception which actually causes the #DF. It should be close
enough, though.
[ hpa: and definitely better than nothing, which is what we have now. ]
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: http://lkml.kernel.org/r/1368093749-31296-1-git-send-email-bp@alien8.de
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Pull perparatory x86 kasrl changes from Ingo Molnar:
"This contains changes from the ongoing KASLR work, by Kees Cook.
The main changes are the use of a read-only IDT on x86 (which
decouples the userspace visible virtual IDT address from the physical
address), and a rework of ELF relocation support, in preparation of
random, boot-time kernel image relocation."
* 'x86-kaslr-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86, relocs: Refactor the relocs tool to merge 32- and 64-bit ELF
x86, relocs: Build separate 32/64-bit tools
x86, relocs: Add 64-bit ELF support to relocs tool
x86, relocs: Consolidate processing logic
x86, relocs: Generalize ELF structure names
x86: Use a read-only IDT alias on all CPUs
Make a copy of the IDT (as seen via the "sidt" instruction) read-only.
This primarily removes the IDT from being a target for arbitrary memory
write attacks, and has the added benefit of also not leaking the kernel
base offset, if it has been relocated.
We already did this on vendor == Intel and family == 5 because of the
F0 0F bug -- regardless of if a particular CPU had the F0 0F bug or
not. Since the workaround was so cheap, there simply was no reason to
be very specific. This patch extends the readonly alias to all CPUs,
but does not activate the #PF to #UD conversion code needed to deliver
the proper exception in the F0 0F case except on Intel family 5
processors.
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: http://lkml.kernel.org/r/20130410192422.GA17344@www.outflux.net
Cc: Eric Northup <digitaleric@google.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
On exception exit, we restore the previous context tracking state based on
the regs of the interrupted frame. Iff that frame is in user mode as
stated by user_mode() helper, we restore the context tracking user mode.
However there is a tiny chunck of low level arch code after we pass through
user_enter() and until the CPU eventually resumes userspace.
If an exception happens in this tiny area, exception_enter() correctly
exits the context tracking user mode but exception_exit() won't restore
it because of the value returned by user_mode(regs).
As a result we may return to userspace with the wrong context tracking
state.
To fix this, change exception_enter() to return the context tracking state
prior to its call and pass this saved state to exception_exit(). This restores
the real context tracking state of the interrupted frame.
(May be this patch was suggested to me, I don't recall exactly. If so,
sorry for the missing credit).
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Mats Liljegren <mats.liljegren@enea.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Namhyung Kim <namhyung.kim@lge.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Exceptions handling on context tracking should share common
treatment: on entry we exit user mode if the exception triggered
in that context. Then on exception exit we return to that previous
context.
Generalize this to avoid duplication across archs.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Mats Liljegren <mats.liljegren@enea.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Namhyung Kim <namhyung.kim@lge.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Linear mode (CR0.PG = 0) is mutually exclusive with 64-bit mode; all
64-bit code has to use page tables. This makes it awkward before we
have first set up properly all-covering page tables to access objects
that are outside the static kernel range.
So far we have dealt with that simply by mapping a fixed amount of
low memory, but that fails in at least two upcoming use cases:
1. We will support load and run kernel, struct boot_params, ramdisk,
command line, etc. above the 4 GiB mark.
2. need to access ramdisk early to get microcode to update that as
early possible.
We could use early_iomap to access them too, but it will make code to
messy and hard to be unified with 32 bit.
Hence, set up a #PF table and use a fixed number of buffers to set up
page tables on demand. If the buffers fill up then we simply flush
them and start over. These buffers are all in __initdata, so it does
not increase RAM usage at runtime.
Thus, with the help of the #PF handler, we can set the final kernel
mapping from blank, and switch to init_level4_pgt later.
During the switchover in head_64.S, before #PF handler is available,
we use three pages to handle kernel crossing 1G, 512G boundaries with
sharing page by playing games with page aliasing: the same page is
mapped twice in the higher-level tables with appropriate wraparound.
The kernel region itself will be properly mapped; other mappings may
be spurious.
early_make_pgtable is using kernel high mapping address to access pages
to set page table.
-v4: Add phys_base offset to make kexec happy, and add
init_mapping_kernel() - Yinghai
-v5: fix compiling with xen, and add back ident level3 and level2 for xen
also move back init_level4_pgt from BSS to DATA again.
because we have to clear it anyway. - Yinghai
-v6: switch to init_level4_pgt in init_mem_mapping. - Yinghai
-v7: remove not needed clear_page for init_level4_page
it is with fill 512,8,0 already in head_64.S - Yinghai
-v8: we need to keep that handler alive until init_mem_mapping and don't
let early_trap_init to trash that early #PF handler.
So split early_trap_pf_init out and move it down. - Yinghai
-v9: switchover only cover kernel space instead of 1G so could avoid
touch possible mem holes. - Yinghai
-v11: change far jmp back to far return to initial_code, that is needed
to fix failure that is reported by Konrad on AMD systems. - Yinghai
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Link: http://lkml.kernel.org/r/1359058816-7615-12-git-send-email-yinghai@kernel.org
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Pull one final 386 removal patch from Peter Anvin.
IRQ 13 FPU error handling is gone. That was not one of the proudest
moments in PC history.
* 'x86/nuke386' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86, 386 removal: Remove support for IRQ 13 FPU error reporting
Remove support for FPU error reporting via IRQ 13, as opposed to
exception 16 (#MF). One last remnant of i386 gone.
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: Alan Cox <alan@linux.intel.com>
Create a new subsystem that probes on kernel boundaries
to keep track of the transitions between level contexts
with two basic initial contexts: user or kernel.
This is an abstraction of some RCU code that use such tracking
to implement its userspace extended quiescent state.
We need to pull this up from RCU into this new level of indirection
because this tracking is also going to be used to implement an "on
demand" generic virtual cputime accounting. A necessary step to
shutdown the tick while still accounting the cputime.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Gilad Ben-Yossef <gilad@benyossef.com>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
[ paulmck: fix whitespace error and email address. ]
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Pull x86/fpu update from Ingo Molnar:
"The biggest change is the addition of the non-lazy (eager) FPU saving
support model and enabling it on CPUs with optimized xsaveopt/xrstor
FPU state saving instructions.
There are also various Sparse fixes"
Fix up trivial add-add conflict in arch/x86/kernel/traps.c
* 'x86-fpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86, kvm: fix kvm's usage of kernel_fpu_begin/end()
x86, fpu: remove cpu_has_xmm check in the fx_finit()
x86, fpu: make eagerfpu= boot param tri-state
x86, fpu: enable eagerfpu by default for xsaveopt
x86, fpu: decouple non-lazy/eager fpu restore from xsave
x86, fpu: use non-lazy fpu restore for processors supporting xsave
lguest, x86: handle guest TS bit for lazy/non-lazy fpu host models
x86, fpu: always use kernel_fpu_begin/end() for in-kernel FPU usage
x86, kvm: use kernel_fpu_begin/end() in kvm_load/put_guest_fpu()
x86, fpu: remove unnecessary user_fpu_end() in save_xstate_sig()
x86, fpu: drop_fpu() before restoring new state from sigframe
x86, fpu: Unify signal handling code paths for x86 and x86_64 kernels
x86, fpu: Consolidate inline asm routines for saving/restoring fpu state
x86, signal: Cleanup ifdefs and is_ia32, is_x32
Pull x86/asm changes from Ingo Molnar:
"The one change that stands out is the alternatives patching change
that prevents us from ever patching back instructions from SMP to UP:
this simplifies things and speeds up CPU hotplug.
Other than that it's smaller fixes, cleanups and improvements."
* 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86: Unspaghettize do_trap()
x86_64: Work around old GAS bug
x86: Use REP BSF unconditionally
x86: Prefer TZCNT over BFS
x86/64: Adjust types of temporaries used by ffs()/fls()/fls64()
x86: Drop unnecessary kernel_eflags variable on 64-bit
x86/smp: Don't ever patch back to UP if we unplug cpus
Add necessary hooks to x86 exception for userspace
RCU extended quiescent state support.
This includes traps, page fault, debug exceptions, etc...
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Alessio Igor Bogani <abogani@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Avi Kivity <avi@redhat.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Geoff Levand <geoff@infradead.org>
Cc: Gilad Ben Yossef <gilad@benyossef.com>
Cc: Hakan Akkan <hakanakkan@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Kevin Hilman <khilman@ti.com>
Cc: Max Krasnyansky <maxk@qualcomm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephen Hemminger <shemminger@vyatta.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Sven-Thorsten Dietrich <thebigcorporation@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
There is some unnatural label based layout in this function.
Convert the unnecessary goto to readable conditional blocks.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cleanup the label maze in this function. Having a
seperate function to first handle the traps that don't
generate a signal makes it easier to convert into
more readable conditional paths.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1348577479-2564-1-git-send-email-fweisbec@gmail.com
[ Fixed 32-bit build failure. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Decouple non-lazy/eager fpu restore policy from the existence of the xsave
feature. Introduce a synthetic CPUID flag to represent the eagerfpu
policy. "eagerfpu=on" boot paramter will enable the policy.
Requested-by: H. Peter Anvin <hpa@zytor.com>
Requested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Link: http://lkml.kernel.org/r/1347300665-6209-2-git-send-email-suresh.b.siddha@intel.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Fundamental model of the current Linux kernel is to lazily init and
restore FPU instead of restoring the task state during context switch.
This changes that fundamental lazy model to the non-lazy model for
the processors supporting xsave feature.
Reasons driving this model change are:
i. Newer processors support optimized state save/restore using xsaveopt and
xrstor by tracking the INIT state and MODIFIED state during context-switch.
This is faster than modifying the cr0.TS bit which has serializing semantics.
ii. Newer glibc versions use SSE for some of the optimized copy/clear routines.
With certain workloads (like boot, kernel-compilation etc), application
completes its work with in the first 5 task switches, thus taking upto 5 #DNA
traps with the kernel not getting a chance to apply the above mentioned
pre-load heuristic.
iii. Some xstate features (like AMD's LWP feature) don't honor the cr0.TS bit
and thus will not work correctly in the presence of lazy restore. Non-lazy
state restore is needed for enabling such features.
Some data on a two socket SNB system:
* Saved 20K DNA exceptions during boot on a two socket SNB system.
* Saved 50K DNA exceptions during kernel-compilation workload.
* Improved throughput of the AVX based checksumming function inside the
kernel by ~15% as xsave/xrstor is faster than the serializing clts/stts
pair.
Also now kernel_fpu_begin/end() relies on the patched
alternative instructions. So move check_fpu() which uses the
kernel_fpu_begin/end() after alternative_instructions().
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Link: http://lkml.kernel.org/r/1345842782-24175-7-git-send-email-suresh.b.siddha@intel.com
Merge 32-bit boot fix from,
Link: http://lkml.kernel.org/r/1347300665-6209-4-git-send-email-suresh.b.siddha@intel.com
Cc: Jim Kukunas <james.t.kukunas@linux.intel.com>
Cc: NeilBrown <neilb@suse.de>
Cc: Avi Kivity <avi@redhat.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Use a more current logging style:
- Bare printks should have a KERN_<LEVEL> for consistency's sake
- Add pr_fmt where appropriate
- Neaten some macro definitions
- Convert some Ok output to OK
- Use "%s: ", __func__ in pr_fmt for summit
- Convert some printks to pr_<level>
Message output is not identical in all cases.
Signed-off-by: Joe Perches <joe@perches.com>
Cc: levinsasha928@gmail.com
Link: http://lkml.kernel.org/r/1337655007.24226.10.camel@joe2Laptop
[ merged two similar patches, tidied up the changelog ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When the function tracer starts modifying the code via breakpoints
it sets a variable (modifying_ftrace_code) to inform the breakpoint
handler to call the ftrace int3 code.
But there's no synchronization between setting this code and the
handler, thus it is possible for the handler to be called on another
CPU before it sees the variable. This will cause a kernel crash as
the int3 handler will not know what to do with it.
I originally added smp_mb()'s to force the visibility of the variable
but H. Peter Anvin suggested that I just make it atomic.
[ Added comments as suggested by Peter Zijlstra ]
Suggested-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Pull the MCA deletion branch from Paul Gortmaker:
"It was good that we could support MCA machines back in the day, but
realistically, nobody is using them anymore. They were mostly limited
to 386-sx 16MHz CPU and some 486 class machines and never more than
64MB of RAM. Even the enthusiast hobbyist community seems to have
dried up close to ten years ago, based on what you can find searching
various websites dedicated to the relatively short lived hardware.
So lets remove the support relating to CONFIG_MCA. There is no point
carrying this forward, wasting cycles doing routine maintenance on it;
wasting allyesconfig build time on validating it, wasting I/O on git
grep'ping over it, and so on."
Let's see if anybody screams. It generally has compiled, and James
Bottomley pointed out that there was a MCA extension from NCR that
allowed for up to 4GB of memory and PPro-class machines. So in *theory*
there may be users out there.
But even James (technically listed as a maintainer) doesn't actually
have a system, and while Alan Cox claims to have a machine in his cellar
that he offered to anybody who wants to take it off his hands, he didn't
argue for keeping MCA support either.
So we could bring it back. But somebody had better speak up and talk
about how they have actually been using said MCA hardware with modern
kernels for us to do that. And David already took the patch to delete
all the networking driver code (commit a5e371f61a: "drivers/net:
delete all code/drivers depending on CONFIG_MCA").
* 'delete-mca' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux:
MCA: delete all remaining traces of microchannel bus support.
scsi: delete the MCA specific drivers and driver code
serial: delete the MCA specific 8250 support.
arm: remove ability to select CONFIG_MCA
Hardware with MCA bus is limited to 386 and 486 class machines
that are now 20+ years old and typically with less than 32MB
of memory. A quick search on the internet, and you see that
even the MCA hobbyist/enthusiast community has lost interest
in the early 2000 era and never really even moved ahead from
the 2.4 kernels to the 2.6 series.
This deletes anything remaining related to CONFIG_MCA from core
kernel code and from the x86 architecture. There is no point in
carrying this any further into the future.
One complication to watch for is inadvertently scooping up
stuff relating to machine check, since there is overlap in
the TLA name space (e.g. arch/x86/boot/mca.c).
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: James Bottomley <JBottomley@Parallels.com>
Cc: x86@kernel.org
Acked-by: Ingo Molnar <mingo@elte.hu>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
This method changes x86 to add a breakpoint to the mcount locations
instead of calling stop machine.
Now that iret can be handled by NMIs, we perform the following to
update code:
1) Add a breakpoint to all locations that will be modified
2) Sync all cores
3) Update all locations to be either a nop or call (except breakpoint
op)
4) Sync all cores
5) Remove the breakpoint with the new code.
6) Sync all cores
[
Added updates that Masami suggested:
Use unlikely(modifying_ftrace_code) in int3 trap to keep kprobes efficient.
Don't use NOTIFY_* in ftrace handler in int3 as it is not a notifier.
]
Cc: H. Peter Anvin <hpa@zytor.com>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
