This makes us recognize when we try to restore FPU state that matches
what we already have in the FPU on this CPU, and avoids the restore
entirely if so.
To do this, we add two new data fields:
- a percpu 'fpu_owner_task' variable that gets written any time we
update the "has_fpu" field, and thus acts as a kind of back-pointer
to the task that owns the CPU. The exception is when we save the FPU
state as part of a context switch - if the save can keep the FPU
state around, we leave the 'fpu_owner_task' variable pointing at the
task whose FP state still remains on the CPU.
- a per-thread 'last_cpu' field, that indicates which CPU that thread
used its FPU on last. We update this on every context switch
(writing an invalid CPU number if the last context switch didn't
leave the FPU in a lazily usable state), so we know that *that*
thread has done nothing else with the FPU since.
These two fields together can be used when next switching back to the
task to see if the CPU still matches: if 'fpu_owner_task' matches the
task we are switching to, we know that no other task (or kernel FPU
usage) touched the FPU on this CPU in the meantime, and if the current
CPU number matches the 'last_cpu' field, we know that this thread did no
other FP work on any other CPU, so the FPU state on the CPU must match
what was saved on last context switch.
In that case, we can avoid the 'f[x]rstor' entirely, and just clear the
CR0.TS bit.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This inlines what is usually just a couple of instructions, but more
importantly it also fixes the theoretical error case (can that FPU
restore really ever fail? Maybe we should remove the checking).
We can't start sending signals from within the scheduler, we're much too
deep in the kernel and are holding the runqueue lock etc. So don't
bother even trying.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This makes sure we clear the FPU usage counter for newly created tasks,
just so that we start off in a known state (for example, don't try to
preload the FPU state on the first task switch etc).
It also fixes a thinko in when we increment the fpu_counter at task
switch time, introduced by commit 34ddc81a23 ("i387: re-introduce FPU
state preloading at context switch time"). We should increment the
*new* task fpu_counter, not the old task, and only if we decide to use
that state (whether lazily or preloaded).
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
After all the FPU state cleanups and finally finding the problem that
caused all our FPU save/restore problems, this re-introduces the
preloading of FPU state that was removed in commit b3b0870ef3 ("i387:
do not preload FPU state at task switch time").
However, instead of simply reverting the removal, this reimplements
preloading with several fixes, most notably
- properly abstracted as a true FPU state switch, rather than as
open-coded save and restore with various hacks.
In particular, implementing it as a proper FPU state switch allows us
to optimize the CR0.TS flag accesses: there is no reason to set the
TS bit only to then almost immediately clear it again. CR0 accesses
are quite slow and expensive, don't flip the bit back and forth for
no good reason.
- Make sure that the same model works for both x86-32 and x86-64, so
that there are no gratuitous differences between the two due to the
way they save and restore segment state differently due to
architectural differences that really don't matter to the FPU state.
- Avoid exposing the "preload" state to the context switch routines,
and in particular allow the concept of lazy state restore: if nothing
else has used the FPU in the meantime, and the process is still on
the same CPU, we can avoid restoring state from memory entirely, just
re-expose the state that is still in the FPU unit.
That optimized lazy restore isn't actually implemented here, but the
infrastructure is set up for it. Of course, older CPU's that use
'fnsave' to save the state cannot take advantage of this, since the
state saving also trashes the state.
In other words, there is now an actual _design_ to the FPU state saving,
rather than just random historical baggage. Hopefully it's easier to
follow as a result.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This moves the bit that indicates whether a thread has ownership of the
FPU from the TS_USEDFPU bit in thread_info->status to a word of its own
(called 'has_fpu') in task_struct->thread.has_fpu.
This fixes two independent bugs at the same time:
- changing 'thread_info->status' from the scheduler causes nasty
problems for the other users of that variable, since it is defined to
be thread-synchronous (that's what the "TS_" part of the naming was
supposed to indicate).
So perfectly valid code could (and did) do
ti->status |= TS_RESTORE_SIGMASK;
and the compiler was free to do that as separate load, or and store
instructions. Which can cause problems with preemption, since a task
switch could happen in between, and change the TS_USEDFPU bit. The
change to TS_USEDFPU would be overwritten by the final store.
In practice, this seldom happened, though, because the 'status' field
was seldom used more than once, so gcc would generally tend to
generate code that used a read-modify-write instruction and thus
happened to avoid this problem - RMW instructions are naturally low
fat and preemption-safe.
- On x86-32, the current_thread_info() pointer would, during interrupts
and softirqs, point to a *copy* of the real thread_info, because
x86-32 uses %esp to calculate the thread_info address, and thus the
separate irq (and softirq) stacks would cause these kinds of odd
thread_info copy aliases.
This is normally not a problem, since interrupts aren't supposed to
look at thread information anyway (what thread is running at
interrupt time really isn't very well-defined), but it confused the
heck out of irq_fpu_usable() and the code that tried to squirrel
away the FPU state.
(It also caused untold confusion for us poor kernel developers).
It also turns out that using 'task_struct' is actually much more natural
for most of the call sites that care about the FPU state, since they
tend to work with the task struct for other reasons anyway (ie
scheduling). And the FPU data that we are going to save/restore is
found there too.
Thanks to Arjan Van De Ven <arjan@linux.intel.com> for pointing us to
the %esp issue.
Cc: Arjan van de Ven <arjan@linux.intel.com>
Reported-and-tested-by: Raphael Prevost <raphael@buro.asia>
Acked-and-tested-by: Suresh Siddha <suresh.b.siddha@intel.com>
Tested-by: Peter Anvin <hpa@zytor.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The AMD K7/K8 CPUs don't save/restore FDP/FIP/FOP unless an exception is
pending. In order to not leak FIP state from one process to another, we
need to do a floating point load after the fxsave of the old process,
and before the fxrstor of the new FPU state. That resets the state to
the (uninteresting) kernel load, rather than some potentially sensitive
user information.
We used to do this directly after the FPU state save, but that is
actually very inconvenient, since it
(a) corrupts what is potentially perfectly good FPU state that we might
want to lazy avoid restoring later and
(b) on x86-64 it resulted in a very annoying ordering constraint, where
"__unlazy_fpu()" in the task switch needs to be delayed until after
the DS segment has been reloaded just to get the new DS value.
Coupling it to the fxrstor instead of the fxsave automatically avoids
both of these issues, and also ensures that we only do it when actually
necessary (the FP state after a save may never actually get used). It's
simply a much more natural place for the leaked state cleanup.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Yes, taking the trap to re-load the FPU/MMX state is expensive, but so
is spending several days looking for a bug in the state save/restore
code. And the preload code has some rather subtle interactions with
both paravirtualization support and segment state restore, so it's not
nearly as simple as it should be.
Also, now that we no longer necessarily depend on a single bit (ie
TS_USEDFPU) for keeping track of the state of the FPU, we migth be able
to do better. If we are really switching between two processes that
keep touching the FP state, save/restore is inevitable, but in the case
of having one process that does most of the FPU usage, we may actually
be able to do much better than the preloading.
In particular, we may be able to keep track of which CPU the process ran
on last, and also per CPU keep track of which process' FP state that CPU
has. For modern CPU's that don't destroy the FPU contents on save time,
that would allow us to do a lazy restore by just re-enabling the
existing FPU state - with no restore cost at all!
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This creates three helper functions that do the TS_USEDFPU accesses, and
makes everybody that used to do it by hand use those helpers instead.
In addition, there's a couple of helper functions for the "change both
CR0.TS and TS_USEDFPU at the same time" case, and the places that do
that together have been changed to use those. That means that we have
fewer random places that open-code this situation.
The intent is partly to clarify the code without actually changing any
semantics yet (since we clearly still have some hard to reproduce bug in
this area), but also to make it much easier to use another approach
entirely to caching the CR0.TS bit for software accesses.
Right now we use a bit in the thread-info 'status' variable (this patch
does not change that), but we might want to make it a full field of its
own or even make it a per-cpu variable.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Touching TS_USEDFPU without touching CR0.TS is confusing, so don't do
it. By moving it into the callers, we always do the TS_USEDFPU next to
the CR0.TS accesses in the source code, and it's much easier to see how
the two go hand in hand.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 5b1cbac377 ("i387: make irq_fpu_usable() tests more robust")
added a sanity check to the #NM handler to verify that we never cause
the "Device Not Available" exception in kernel mode.
However, that check actually pinpointed a (fundamental) race where we do
cause that exception as part of the signal stack FPU state save/restore
code.
Because we use the floating point instructions themselves to save and
restore state directly from user mode, we cannot do that atomically with
testing the TS_USEDFPU bit: the user mode access itself may cause a page
fault, which causes a task switch, which saves and restores the FP/MMX
state from the kernel buffers.
This kind of "recursive" FP state save is fine per se, but it means that
when the signal stack save/restore gets restarted, it will now take the
'#NM' exception we originally tried to avoid. With preemption this can
happen even without the page fault - but because of the user access, we
cannot just disable preemption around the save/restore instruction.
There are various ways to solve this, including using the
"enable/disable_page_fault()" helpers to not allow page faults at all
during the sequence, and fall back to copying things by hand without the
use of the native FP state save/restore instructions.
However, the simplest thing to do is to just allow the #NM from kernel
space, but fix the race in setting and clearing CR0.TS that this all
exposed: the TS bit changes and the TS_USEDFPU bit absolutely have to be
atomic wrt scheduling, so while the actual state save/restore can be
interrupted and restarted, the act of actually clearing/setting CR0.TS
and the TS_USEDFPU bit together must not.
Instead of just adding random "preempt_disable/enable()" calls to what
is already excessively ugly code, this introduces some helper functions
that mostly mirror the "kernel_fpu_begin/end()" functionality, just for
the user state instead.
Those helper functions should probably eventually replace the other
ad-hoc CR0.TS and TS_USEDFPU tests too, but I'll need to think about it
some more: the task switching functionality in particular needs to
expose the difference between the 'prev' and 'next' threads, while the
new helper functions intentionally were written to only work with
'current'.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The check for save_init_fpu() (introduced in commit 5b1cbac377: "i387:
make irq_fpu_usable() tests more robust") was the wrong way around, but
I hadn't noticed, because my "tests" were bogus: the FPU exceptions are
disabled by default, so even doing a divide by zero never actually
triggers this code at all unless you do extra work to enable them.
So if anybody did enable them, they'd get one spurious warning.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
by the xen-pci[front|back] to conform to the one used in majority of
PCI drivers; Two fixes to make the code more resilient to invalid
configurations.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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Merge tag 'stable/for-linus-fixes-3.3-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen
Two fixes for VCPU offlining; One to fix the string format exposed
by the xen-pci[front|back] to conform to the one used in majority of
PCI drivers; Two fixes to make the code more resilient to invalid
configurations.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* tag 'stable/for-linus-fixes-3.3-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen:
xenbus_dev: add missing error check to watch handling
xen/pci[front|back]: Use %d instead of %1x for displaying PCI devfn.
xen pvhvm: do not remap pirqs onto evtchns if !xen_have_vector_callback
xen/smp: Fix CPU online/offline bug triggering a BUG: scheduling while atomic.
xen/bootup: During bootup suppress XENBUS: Unable to read cpu state
Some code - especially the crypto layer - wants to use the x86
FP/MMX/AVX register set in what may be interrupt (typically softirq)
context.
That *can* be ok, but the tests for when it was ok were somewhat
suspect. We cannot touch the thread-specific status bits either, so
we'd better check that we're not going to try to save FP state or
anything like that.
Now, it may be that the TS bit is always cleared *before* we set the
USEDFPU bit (and only set when we had already cleared the USEDFP
before), so the TS bit test may actually have been sufficient, but it
certainly was not obviously so.
So this explicitly verifies that we will not touch the TS_USEDFPU bit,
and adds a few related sanity-checks. Because it seems that somehow
AES-NI is corrupting user FP state. The cause is not clear, and this
patch doesn't fix it, but while debugging it I really wanted the code to
be more obviously correct and robust.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
It was marked asmlinkage for some really old and stale legacy reasons.
Fix that and the equally stale comment.
Noticed when debugging the irq_fpu_usable() bugs.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf: Fix double start/stop in x86_pmu_start()
perf evsel: Fix an issue where perf report fails to show the proper percentage
perf tools: Fix prefix matching for kernel maps
perf tools: Fix perf stack to non executable on x86_64
perf: Remove deprecated WARN_ON_ONCE()
The following patch fixes a bug introduced by the following
commit:
e050e3f0a7 ("perf: Fix broken interrupt rate throttling")
The patch caused the following warning to pop up depending on
the sampling frequency adjustments:
------------[ cut here ]------------
WARNING: at arch/x86/kernel/cpu/perf_event.c:995 x86_pmu_start+0x79/0xd4()
It was caused by the following call sequence:
perf_adjust_freq_unthr_context.part() {
stop()
if (delta > 0) {
perf_adjust_period() {
if (period > 8*...) {
stop()
...
start()
}
}
}
start()
}
Which caused a double start and a double stop, thus triggering
the assert in x86_pmu_start().
The patch fixes the problem by avoiding the double calls. We
pass a new argument to perf_adjust_period() to indicate whether
or not the event is already stopped. We can't just remove the
start/stop from that function because it's called from
__perf_event_overflow where the event needs to be reloaded via a
stop/start back-toback call.
The patch reintroduces the assertion in x86_pmu_start() which
was removed by commit:
84f2b9b ("perf: Remove deprecated WARN_ON_ONCE()")
In this second version, we've added calls to disable/enable PMU
during unthrottling or frequency adjustment based on bug report
of spurious NMI interrupts from Eric Dumazet.
Reported-and-tested-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Stephane Eranian <eranian@google.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: markus@trippelsdorf.de
Cc: paulus@samba.org
Link: http://lkml.kernel.org/r/20120207133956.GA4932@quad
[ Minor edits to the changelog and to the code ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Fixing a regression with the PMU MSRs when PMU virtualization is
disabled, a guest-internal DoS with the SYSCALL instruction, and a dirty
memory logging race that may cause live migration to fail.
* 'kvm-updates/3.3' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
KVM: do not #GP on perf MSR writes when vPMU is disabled
KVM: x86: fix missing checks in syscall emulation
KVM: x86: extend "struct x86_emulate_ops" with "get_cpuid"
KVM: Fix __set_bit() race in mark_page_dirty() during dirty logging
When a user offlines a VCPU and then onlines it, we get:
NMI watchdog disabled (cpu2): hardware events not enabled
BUG: scheduling while atomic: swapper/2/0/0x00000002
Modules linked in: dm_multipath dm_mod xen_evtchn iscsi_boot_sysfs iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi scsi_mod libcrc32c crc32c radeon fbco
ttm bitblit softcursor drm_kms_helper xen_blkfront xen_netfront xen_fbfront fb_sys_fops sysimgblt sysfillrect syscopyarea xen_kbdfront xenfs [last unloaded:
Pid: 0, comm: swapper/2 Tainted: G O 3.2.0phase15.1-00003-gd6f7f5b-dirty #4
Call Trace:
[<ffffffff81070571>] __schedule_bug+0x61/0x70
[<ffffffff8158eb78>] __schedule+0x798/0x850
[<ffffffff8158ed6a>] schedule+0x3a/0x50
[<ffffffff810349be>] cpu_idle+0xbe/0xe0
[<ffffffff81583599>] cpu_bringup_and_idle+0xe/0x10
The reason for this should be obvious from this call-chain:
cpu_bringup_and_idle:
\- cpu_bringup
| \-[preempt_disable]
|
|- cpu_idle
\- play_dead [assuming the user offlined the VCPU]
| \
| +- (xen_play_dead)
| \- HYPERVISOR_VCPU_off [so VCPU is dead, once user
| | onlines it starts from here]
| \- cpu_bringup [preempt_disable]
|
+- preempt_enable_no_reschedule()
+- schedule()
\- preempt_enable()
So we have two preempt_disble() and one preempt_enable(). Calling
preempt_enable() after the cpu_bringup() in the xen_play_dead
fixes the imbalance.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
With the new throttling/unthrottling code introduced with
commit:
e050e3f0a7 ("perf: Fix broken interrupt rate throttling")
we occasionally hit two WARN_ON_ONCE() checks in:
- intel_pmu_pebs_enable()
- intel_pmu_lbr_enable()
- x86_pmu_start()
The assertions are no longer problematic. There is a valid
path where they can trigger but it is harmless.
The assertion can be triggered with:
$ perf record -e instructions:pp ....
Leading to paths:
intel_pmu_pebs_enable
intel_pmu_enable_event
x86_perf_event_set_period
x86_pmu_start
perf_adjust_freq_unthr_context
perf_event_task_tick
scheduler_tick
And:
intel_pmu_lbr_enable
intel_pmu_enable_event
x86_perf_event_set_period
x86_pmu_start
perf_adjust_freq_unthr_context.
perf_event_task_tick
scheduler_tick
cpuc->enabled is always on because when we get to
perf_adjust_freq_unthr_context() the PMU is not totally
disabled. Furthermore when we need to adjust a period,
we only stop the event we need to change and not the
entire PMU. Thus, when we re-enable, cpuc->enabled is
already set. Note that when we stop the event, both
pebs and lbr are stopped if necessary (and possible).
Signed-off-by: Stephane Eranian <eranian@google.com>
Cc: peterz@infradead.org
Link: http://lkml.kernel.org/r/20120202110401.GA30911@quad
Signed-off-by: Ingo Molnar <mingo@elte.hu>
* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
bugs, x86: Fix printk levels for panic, softlockups and stack dumps
* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf top: Fix number of samples displayed
perf tools: Fix strlen() bug in perf_event__synthesize_event_type()
perf tools: Fix broken build by defining _GNU_SOURCE in Makefile
x86/dumpstack: Remove unneeded check in dump_trace()
perf: Fix broken interrupt rate throttling
* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/rt: Fix task stack corruption under __ARCH_WANT_INTERRUPTS_ON_CTXSW
sched: Fix ancient race in do_exit()
sched/nohz: Fix nohz cpu idle load balancing state with cpu hotplug
sched/s390: Fix compile error in sched/core.c
sched: Fix rq->nr_uninterruptible update race
* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/reboot: Remove VersaLogic Menlow reboot quirk
x86/reboot: Skip DMI checks if reboot set by user
x86: Properly parenthesize cmpxchg() macro arguments
Return to behaviour perf MSR had before introducing vPMU in case vPMU
is disabled. Some guests access those registers unconditionally and do
not expect it to fail.
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
On hosts without this patch, 32bit guests will crash (and 64bit guests
may behave in a wrong way) for example by simply executing following
nasm-demo-application:
[bits 32]
global _start
SECTION .text
_start: syscall
(I tested it with winxp and linux - both always crashed)
Disassembly of section .text:
00000000 <_start>:
0: 0f 05 syscall
The reason seems a missing "invalid opcode"-trap (int6) for the
syscall opcode "0f05", which is not available on Intel CPUs
within non-longmodes, as also on some AMD CPUs within legacy-mode.
(depending on CPU vendor, MSR_EFER and cpuid)
Because previous mentioned OSs may not engage corresponding
syscall target-registers (STAR, LSTAR, CSTAR), they remain
NULL and (non trapping) syscalls are leading to multiple
faults and finally crashs.
Depending on the architecture (AMD or Intel) pretended by
guests, various checks according to vendor's documentation
are implemented to overcome the current issue and behave
like the CPUs physical counterparts.
[mtosatti: cleanup/beautify code]
Signed-off-by: Stephan Baerwolf <stephan.baerwolf@tu-ilmenau.de>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
In order to be able to proceed checks on CPU-specific properties
within the emulator, function "get_cpuid" is introduced.
With "get_cpuid" it is possible to virtually call the guests
"cpuid"-opcode without changing the VM's context.
[mtosatti: cleanup/beautify code]
Signed-off-by: Stephan Baerwolf <stephan.baerwolf@tu-ilmenau.de>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
This commit removes the reboot quirk originally added by commit
e19e074 ("x86: Fix reboot problem on VersaLogic Menlow boards").
Testing with a VersaLogic Ocelot (VL-EPMs-21a rev 1.00 w/ BIOS
6.5.102) revealed the following regarding the reboot hang
problem:
- v2.6.37 reboot=bios was needed.
- v2.6.38-rc1: behavior changed, reboot=acpi is needed,
reboot=kbd and reboot=bios results in system hang.
- v2.6.38: VersaLogic patch (e19e074 "x86: Fix reboot problem on
VersaLogic Menlow boards") was applied prior to v2.6.38-rc7. This
patch sets a quirk for VersaLogic Menlow boards that forces the use
of reboot=bios, which doesn't work anymore.
- v3.2: It seems that commit 660e34c ("x86: Reorder reboot method
preferences") changed the default reboot method to acpi prior to
v3.0-rc1, which means the default behavior is appropriate for the
Ocelot. No VersaLogic quirk is required.
The Ocelot board used for testing can successfully reboot w/out
having to pass any reboot= arguments for all 3 current versions
of the BIOS.
Signed-off-by: Michael D Labriola <michael.d.labriola@gmail.com>
Cc: Matthew Garrett <mjg@redhat.com>
Cc: Michael D Labriola <mlabriol@gdeb.com>
Cc: Kushal Koolwal <kushalkoolwal@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/87vcnub9hu.fsf@gmail.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Skip DMI checks for vendor specific reboot quirks if the user
passed in a reboot= arg on the command line - we should never
override user choices.
Signed-off-by: Michael D Labriola <michael.d.labriola@gmail.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Michael D Labriola <mlabriol@gdeb.com>
Cc: Matthew Garrett <mjg@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/87wr8ab9od.fsf@gmail.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
* 'stable/for-linus-fixes-3.3' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen:
xen/granttable: Disable grant v2 for HVM domains.
x86: xen: size struct xen_spinlock to always fit in arch_spinlock_t
Smatch complains that we have some inconsistent NULL checking.
If "task" were NULL then it would lead to a NULL dereference
later. We can remove this test because earlier on in the
function we have:
if (!task)
task = current;
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Clemens Ladisch <clemens@ladisch.de>
Link: http://lkml.kernel.org/r/20120128105246.GA25092@elgon.mountain
Signed-off-by: Ingo Molnar <mingo@elte.hu>
* commit 'v3.3-rc1': (9775 commits)
Linux 3.3-rc1
x86, syscall: Need __ARCH_WANT_SYS_IPC for 32 bits
qnx4: don't leak ->BitMap on late failure exits
qnx4: reduce the insane nesting in qnx4_checkroot()
qnx4: di_fname is an array, for crying out loud...
KEYS: Permit key_serial() to be called with a const key pointer
keys: fix user_defined key sparse messages
ima: fix cred sparse warning
uml: fix compile for x86-64
MPILIB: Add a missing ENOMEM check
tpm: fix (ACPI S3) suspend regression
nvme: fix merge error due to change of 'make_request_fn' fn type
xen: using EXPORT_SYMBOL requires including export.h
gpio: tps65910: Use correct offset for gpio initialization
acpi/apei/einj: Add extensions to EINJ from rev 5.0 of acpi spec
intel_idle: Split up and provide per CPU initialization func
ACPI processor: Remove unneeded variable passed by acpi_processor_hotadd_init V2
tg3: Fix single-vector MSI-X code
openvswitch: Fix multipart datapath dumps.
ipv6: fix per device IP snmp counters
...
rsyslog will display KERN_EMERG messages on a connected
terminal. However, these messages are useless/undecipherable
for a general user.
For example, after a softlockup we get:
Message from syslogd@intel-s3e37-04 at Jan 25 14:18:06 ...
kernel:Stack:
Message from syslogd@intel-s3e37-04 at Jan 25 14:18:06 ...
kernel:Call Trace:
Message from syslogd@intel-s3e37-04 at Jan 25 14:18:06 ...
kernel:Code: ff ff a8 08 75 25 31 d2 48 8d 86 38 e0 ff ff 48 89
d1 0f 01 c8 0f ae f0 48 8b 86 38 e0 ff ff a8 08 75 08 b1 01 4c 89 e0 0f 01 c9 <e8> ea 69 dd ff 4c 29 e8 48 89 c7 e8 0f bc da ff 49 89 c4 49 89
This happens because the printk levels for these messages are
incorrect. Only an informational message should be displayed on
a terminal.
I modified the printk levels for various messages in the kernel
and tested the output by using the drivers/misc/lkdtm.c kernel
modules (ie, softlockups, panics, hard lockups, etc.) and
confirmed that the console output was still the same and that
the output to the terminals was correct.
For example, in the case of a softlockup we now see the much
more informative:
Message from syslogd@intel-s3e37-04 at Jan 25 10:18:06 ...
BUG: soft lockup - CPU4 stuck for 60s!
instead of the above confusing messages.
AFAICT, the messages no longer have to be KERN_EMERG. In the
most important case of a panic we set console_verbose(). As for
the other less severe cases the correct data is output to the
console and /var/log/messages.
Successfully tested by me using the drivers/misc/lkdtm.c module.
Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Cc: dzickus@redhat.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/1327586134-11926-1-git-send-email-prarit@redhat.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Quite oddly, all of the arguments passed through from the top
level macros to the second level which didn't need parentheses
had them, while the only expression (involving a parameter)
needing them didn't.
Very recently I got bitten by the lack thereof when using
something like "array + index" for the first operand, with
"array" being an array more narrow than int.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/4F2183A9020000780006F3E6@nat28.tlf.novell.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
We've decided to provide CPU family specific container files
(starting with CPU family 15h). E.g. for family 15h we have to
load microcode_amd_fam15h.bin instead of microcode_amd.bin
Rationale is that starting with family 15h patch size is larger
than 2KB which was hard coded as maximum patch size in various
microcode loaders (not just Linux).
Container files which include patches larger than 2KB cause
different kinds of trouble with such old patch loaders. Thus we
have to ensure that the default container file provides only
patches with size less than 2KB.
Signed-off-by: Andreas Herrmann <andreas.herrmann3@amd.com>
Cc: Borislav Petkov <borislav.petkov@amd.com>
Cc: <stable@kernel.org>
Link: http://lkml.kernel.org/r/20120120164412.GD24508@alberich.amd.com
[ documented the naming convention and tidied the code a bit. ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
That is the last one missing for those CPUs.
Others were recently added with commits
fb215366b3
(KVM: expose latest Intel cpu new features (BMI1/BMI2/FMA/AVX2) to guest)
and
commit 969df4b829
(x86: Report cpb and eff_freq_ro flags correctly)
Signed-off-by: Andreas Herrmann <andreas.herrmann3@amd.com>
Link: http://lkml.kernel.org/r/20120120163823.GC24508@alberich.amd.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Initialize two spinlocks in tlb_uv.c and also properly define/initialize
the uv_irq_lock.
The lack of explicit initialization seems to be functionally
harmless, but it is diagnosed when these are turned on:
CONFIG_DEBUG_SPINLOCK=y
CONFIG_DEBUG_MUTEXES=y
CONFIG_DEBUG_LOCK_ALLOC=y
CONFIG_LOCKDEP=y
Signed-off-by: Cliff Wickman <cpw@sgi.com>
Cc: <stable@kernel.org>
Cc: Dimitri Sivanich <sivanich@sgi.com>
Link: http://lkml.kernel.org/r/E1RnXd1-0003wU-PM@eag09.americas.sgi.com
[ Added the uv_irq_lock initialization fix by Dimitri Sivanich ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
uv_gpa_to_soc_phys_ram() was inadvertently ignoring the
shift values. This fix takes the shift into account.
Signed-off-by: Russ Anderson <rja@sgi.com>
Cc: <stable@kernel.org>
Link: http://lkml.kernel.org/r/20120119020753.GA7228@sgi.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Davem says:
1) Fix JIT code generation on x86-64 for divide by zero, from Eric Dumazet.
2) tg3 header length computation correction from Eric Dumazet.
3) More build and reference counting fixes for socket memory cgroup
code from Glauber Costa.
4) module.h snuck back into a core header after all the hard work we
did to remove that, from Paul Gortmaker and Jesper Dangaard Brouer.
5) Fix PHY naming regression and add some new PCI IDs in stmmac, from
Alessandro Rubini.
6) Netlink message generation fix in new team driver, should only advertise
the entries that changed during events, from Jiri Pirko.
7) SRIOV VF registration and unregistration fixes, and also add a
missing PCI ID, from Roopa Prabhu.
8) Fix infinite loop in tx queue flush code of brcmsmac, from Stanislaw Gruszka.
9) ftgmac100/ftmac100 build fix, missing interrupt.h include.
10) Memory leak fix in net/hyperv do_set_mutlicast() handling, from Wei Yongjun.
11) Off by one fix in netem packet scheduler, from Vijay Subramanian.
12) TCP loss detection fix from Yuchung Cheng.
13) TCP reset packet MD5 calculation uses wrong address, fix from Shawn Lu.
14) skge carrier assertion and DMA mapping fixes from Stephen Hemminger.
15) Congestion recovery undo performed at the wrong spot in BIC and CUBIC
congestion control modules, fix from Neal Cardwell.
16) Ethtool ETHTOOL_GSSET_INFO is unnecessarily restrictive, from Michał Mirosław.
17) Fix triggerable race in ipv6 sysctl handling, from Francesco Ruggeri.
18) Statistics bug fixes in mlx4 from Eugenia Emantayev.
19) rds locking bug fix during info dumps, from your's truly.
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (67 commits)
rds: Make rds_sock_lock BH rather than IRQ safe.
netprio_cgroup.h: dont include module.h from other includes
net: flow_dissector.c missing include linux/export.h
team: send only changed options/ports via netlink
net/hyperv: fix possible memory leak in do_set_multicast()
drivers/net: dsa/mv88e6xxx.c files need linux/module.h
stmmac: added PCI identifiers
llc: Fix race condition in llc_ui_recvmsg
stmmac: fix phy naming inconsistency
dsa: Add reporting of silicon revision for Marvell 88E6123/88E6161/88E6165 switches.
tg3: fix ipv6 header length computation
skge: add byte queue limit support
mv643xx_eth: Add Rx Discard and Rx Overrun statistics
bnx2x: fix compilation error with SOE in fw_dump
bnx2x: handle CHIP_REVISION during init_one
bnx2x: allow user to change ring size in ISCSI SD mode
bnx2x: fix Big-Endianess in ethtool -t
bnx2x: fixed ethtool statistics for MF modes
bnx2x: credit-leakage fixup on vlan_mac_del_all
macvlan: fix a possible use after free
...
If NR_CPUS < 256 then arch_spinlock_t is only 16 bits wide but struct
xen_spinlock is 32 bits. When a spin lock is contended and
xl->spinners is modified the two bytes immediately after the spin lock
would be corrupted.
This is a regression caused by 84eb950db1
(x86, ticketlock: Clean up types and accessors) which reduced the size
of arch_spinlock_t.
Fix this by making xl->spinners a u8 if NR_CPUS < 256. A
BUILD_BUG_ON() is also added to check the sizes of the two structures
are compatible.
In many cases this was not noticable as there would often be padding
bytes after the lock (e.g., if any of CONFIG_GENERIC_LOCKBREAK,
CONFIG_DEBUG_SPINLOCK, or CONFIG_DEBUG_LOCK_ALLOC were enabled).
The bnx2 driver is affected. In struct bnx2, phy_lock and
indirect_lock may have no padding after them. Contention on phy_lock
would corrupt indirect_lock making it appear locked and the driver
would deadlock.
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy@goop.org>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
CC: stable@kernel.org #only 3.2
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/accounting, proc: Fix /proc/stat interrupts sum
* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
tracepoints/module: Fix disabling tracepoints with taint CRAP or OOT
x86/kprobes: Add arch/x86/tools/insn_sanity to .gitignore
x86/kprobes: Fix typo transferred from Intel manual
* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86, syscall: Need __ARCH_WANT_SYS_IPC for 32 bits
x86, tsc: Fix SMI induced variation in quick_pit_calibrate()
x86, opcode: ANDN and Group 17 in x86-opcode-map.txt
x86/kconfig: Move the ZONE_DMA entry under a menu
x86/UV2: Add accounting for BAU strong nacks
x86/UV2: Ack BAU interrupt earlier
x86/UV2: Remove stale no-resources test for UV2 BAU
x86/UV2: Work around BAU bug
x86/UV2: Fix BAU destination timeout initialization
x86/UV2: Fix new UV2 hardware by using native UV2 broadcast mode
x86: Get rid of dubious one-bit signed bitfield
In checkin
303395ac3b x86: Generate system call tables and unistd_*.h from tables
the feature macros in <asm/unistd.h> were unified between 32 and 64
bits. Unfortunately 32 bits requires __ARCH_WANT_SYS_IPC and this was
inadvertently dropped.
Reported-by: Dmitry Kasatkin <dmitry.kasatkin@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Link: http://lkml.kernel.org/r/CALLzPKbeXN5gdngo8uYYU8mAow=XhrwBFBhKfG811f37BubQOg@mail.gmail.com
Randy Dunlap reports that we get
arch/x86/um/shared/sysdep/ptrace.h:7:20: error: redefinition of 'regs_return_value'
arch/x86/um/shared/sysdep/ptrace.h:7:20: note: previous definition of 'regs_return_value' was here
when compiling UML for x86-64.
Stephen Rothwell root-caused it and says:
"Caused by commit d7e7528bcd ("Audit: push audit success and retcode
into arch ptrace.h") (another patch that was never in linux-next :-().
This file now needs protection against double inclusion."
so let's do as the man says.
Reported-by: Randy Dunlap <rdunlap@xenotime.net>
Analyzed-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This includes initial support for the recently published ACPI 5.0 spec.
In particular, support for the "hardware-reduced" bit that eliminates
the dependency on legacy hardware.
APEI has patches resulting from testing on real hardware.
Plus other random fixes.
* 'release' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux: (52 commits)
acpi/apei/einj: Add extensions to EINJ from rev 5.0 of acpi spec
intel_idle: Split up and provide per CPU initialization func
ACPI processor: Remove unneeded variable passed by acpi_processor_hotadd_init V2
ACPI processor: Remove unneeded cpuidle_unregister_driver call
intel idle: Make idle driver more robust
intel_idle: Fix a cast to pointer from integer of different size warning in intel_idle
ACPI: kernel-parameters.txt : Add intel_idle.max_cstate
intel_idle: remove redundant local_irq_disable() call
ACPI processor: Fix error path, also remove sysdev link
ACPI: processor: fix acpi_get_cpuid for UP processor
intel_idle: fix API misuse
ACPI APEI: Convert atomicio routines
ACPI: Export interfaces for ioremapping/iounmapping ACPI registers
ACPI: Fix possible alignment issues with GAS 'address' references
ACPI, ia64: Use SRAT table rev to use 8bit or 16/32bit PXM fields (ia64)
ACPI, x86: Use SRAT table rev to use 8bit or 32bit PXM fields (x86/x86-64)
ACPI: Store SRAT table revision
ACPI, APEI, Resolve false conflict between ACPI NVS and APEI
ACPI, Record ACPI NVS regions
ACPI, APEI, EINJ, Refine the fix of resource conflict
...
Several problems fixed in this patch :
1) Target of the conditional jump in case a divide by 0 is performed
by a bpf is wrong.
2) Must 'generate' the full function prologue/epilogue at pass=0,
or else we can stop too early in pass=1 if the proglen doesnt change.
(if the increase of prologue/epilogue equals decrease of all
instructions length because some jumps are converted to near jumps)
3) Change the wrong length detection at the end of code generation to
issue a more explicit message, no need for a full stack trace.
Reported-by: Phil Oester <kernel@linuxace.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
JONGMAN HEO reports:
With current linus git (commit a25a2b84), I got following build error,
arch/x86/kernel/vm86_32.c: In function 'do_sys_vm86':
arch/x86/kernel/vm86_32.c:340: error: implicit declaration of function '__audit_syscall_exit'
make[3]: *** [arch/x86/kernel/vm86_32.o] Error 1
OK, I can reproduce it (32bit allmodconfig with AUDIT=y, AUDITSYSCALL=n)
It's due to commit d7e7528bcd: "Audit: push audit success and retcode
into arch ptrace.h".
Reported-by: JONGMAN HEO <jongman.heo@samsung.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/audit: (29 commits)
audit: no leading space in audit_log_d_path prefix
audit: treat s_id as an untrusted string
audit: fix signedness bug in audit_log_execve_info()
audit: comparison on interprocess fields
audit: implement all object interfield comparisons
audit: allow interfield comparison between gid and ogid
audit: complex interfield comparison helper
audit: allow interfield comparison in audit rules
Kernel: Audit Support For The ARM Platform
audit: do not call audit_getname on error
audit: only allow tasks to set their loginuid if it is -1
audit: remove task argument to audit_set_loginuid
audit: allow audit matching on inode gid
audit: allow matching on obj_uid
audit: remove audit_finish_fork as it can't be called
audit: reject entry,always rules
audit: inline audit_free to simplify the look of generic code
audit: drop audit_set_macxattr as it doesn't do anything
audit: inline checks for not needing to collect aux records
audit: drop some potentially inadvisable likely notations
...
Use evil merge to fix up grammar mistakes in Kconfig file.
Bad speling and horrible grammar (and copious swearing) is to be
expected, but let's keep it to commit messages and comments, rather than
expose it to users in config help texts or printouts.
pit_expect_msb() returns success wrongly in the below SMI scenario:
a. pit_verify_msb() has not yet seen the MSB transition.
b. we are close to the MSB transition though and got a SMI immediately after
returning from pit_verify_msb() which didn't see the MSB transition. PIT MSB
transition has happened somewhere during SMI execution.
c. returned from SMI and we noted down the 'tsc', saw the pit MSB change now and
exited the loop to calculate 'deltatsc'. Instead of noting the TSC at the MSB
transition, we are way off because of the SMI. And as the SMI happened
between the pit_verify_msb() and before the 'tsc' is recorded in the
for loop, 'delattsc' (d1/d2 in quick_pit_calibrate()) will be small and
quick_pit_calibrate() will not notice this error.
Depending on whether SMI disturbance happens while computing d1 or d2, we will
see the TSC calibrated value smaller or bigger than the expected value. As a
result, in a cluster we were seeing a variation of approximately +/- 20MHz in
the calibrated values, resulting in NTP failures.
[ As far as the SMI source is concerned, this is a periodic SMI that gets
disabled after ACPI is enabled by the OS. But the TSC calibration happens
before the ACPI is enabled. ]
To address this, change pit_expect_msb() so that
- the 'tsc' is the TSC in between the two reads that read the MSB
change from the PIT (same as before)
- the 'delta' is the difference in TSC from *before* the MSB changed
to *after* the MSB changed.
Now the delta is twice as big as before (it covers four PIT accesses,
roughly 4us) and quick_pit_calibrate() will loop a bit longer to get
the calibrated value with in the 500ppm precision. As the delta (d1/d2)
covers four PIT accesses, actual calibrated result might be closer to
250ppm precision.
As the loop now takes longer to stabilize, double MAX_QUICK_PIT_MS to 50.
SMI disturbance will showup as much larger delta's and the loop will take
longer than usual for the result to be with in the accepted precision. Or will
fallback to slow PIT calibration if it takes more than 50msec.
Also while we are at this, remove the calibration correction that aims to
get the result to the middle of the error bars. We really don't know which
direction to correct into, so remove it.
Reported-and-tested-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Link: http://lkml.kernel.org/r/1326843337.5291.4.camel@sbsiddha-mobl2
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Every arch calls:
if (unlikely(current->audit_context))
audit_syscall_entry()
which requires knowledge about audit (the existance of audit_context) in
the arch code. Just do it all in static inline in audit.h so that arch's
can remain blissfully ignorant.
Signed-off-by: Eric Paris <eparis@redhat.com>
