When the NMI handler runs, it checks if it preempted a debug handler
and if that handler is using the debug stack. If it is, it changes the
IDT table not to update the stack, otherwise it will reset the debug
stack and corrupt the debug handler it preempted.
Now that ftrace uses breakpoints to change functions from nops to
callers, many more places may hit a breakpoint. Unfortunately this
includes some of the calls that lockdep performs. Which causes issues
with the debug stack. It too needs to change the debug stack before
tracing (if called from the debug handler).
Allow the debug_stack_set_zero() and debug_stack_reset() to be nested
so that the debug handlers can take advantage of them too.
[ Used this_cpu_*() over __get_cpu_var() as suggested by H. Peter Anvin ]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Since percpu_xxx() serial functions are duplicated with this_cpu_xxx().
Removing percpu_xxx() definition and replacing them by this_cpu_xxx()
in code. There is no function change in this patch, just preparation for
later percpu_xxx serial function removing.
On x86 machine the this_cpu_xxx() serial functions are same as
__this_cpu_xxx() without no unnecessary premmpt enable/disable.
Thanks for Stephen Rothwell, he found and fixed a i386 build error in
the patch.
Also thanks for Andrew Morton, he kept updating the patchset in Linus'
tree.
Signed-off-by: Alex Shi <alex.shi@intel.com>
Acked-by: Christoph Lameter <cl@gentwo.org>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
It's only called from amd.c:srat_detect_node(). The introduced
condition for calling the fixup code is true for all AMD
multi-node processors, e.g. Magny-Cours and Interlagos. There we
have 2 NUMA nodes on one socket. Thus there are cores having
different numa-node-id but with equal phys_proc_id.
There is no point to print error messages in such a situation.
The confusing/misleading error message was introduced with
commit 64be4c1c24 ("x86: Add
x86_init platform override to fix up NUMA core numbering").
Remove the default fixup function (especially the error message)
and replace it by a NULL pointer check, move the
Numascale-specific condition for calling the fixup into the
fixup-function itself and slightly adapt the comment.
Signed-off-by: Andreas Herrmann <andreas.herrmann3@amd.com>
Acked-by: Borislav Petkov <borislav.petkov@amd.com>
Cc: <stable@kernel.org>
Cc: <sp@numascale.com>
Cc: <bp@amd64.org>
Cc: <daniel@numascale-asia.com>
Link: http://lkml.kernel.org/r/20120402160648.GR27684@alberich.amd.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull x86 updates from Ingo Molnar.
This touches some non-x86 files due to the sanitized INLINE_SPIN_UNLOCK
config usage.
Fixed up trivial conflicts due to just header include changes (removing
headers due to cpu_idle() merge clashing with the <asm/system.h> split).
* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/apic/amd: Be more verbose about LVT offset assignments
x86, tls: Off by one limit check
x86/ioapic: Add io_apic_ops driver layer to allow interception
x86/olpc: Add debugfs interface for EC commands
x86: Merge the x86_32 and x86_64 cpu_idle() functions
x86/kconfig: Remove CONFIG_TR=y from the defconfigs
x86: Stop recursive fault in print_context_stack after stack overflow
x86/io_apic: Move and reenable irq only when CONFIG_GENERIC_PENDING_IRQ=y
x86/apic: Add separate apic_id_valid() functions for selected apic drivers
locking/kconfig: Simplify INLINE_SPIN_UNLOCK usage
x86/kconfig: Update defconfigs
x86: Fix excessive MSR print out when show_msr is not specified
Pull <linux/bug.h> cleanup from Paul Gortmaker:
"The changes shown here are to unify linux's BUG support under the one
<linux/bug.h> file. Due to historical reasons, we have some BUG code
in bug.h and some in kernel.h -- i.e. the support for BUILD_BUG in
linux/kernel.h predates the addition of linux/bug.h, but old code in
kernel.h wasn't moved to bug.h at that time. As a band-aid, kernel.h
was including <asm/bug.h> to pseudo link them.
This has caused confusion[1] and general yuck/WTF[2] reactions. Here
is an example that violates the principle of least surprise:
CC lib/string.o
lib/string.c: In function 'strlcat':
lib/string.c:225:2: error: implicit declaration of function 'BUILD_BUG_ON'
make[2]: *** [lib/string.o] Error 1
$
$ grep linux/bug.h lib/string.c
#include <linux/bug.h>
$
We've included <linux/bug.h> for the BUG infrastructure and yet we
still get a compile fail! [We've not kernel.h for BUILD_BUG_ON.] Ugh -
very confusing for someone who is new to kernel development.
With the above in mind, the goals of this changeset are:
1) find and fix any include/*.h files that were relying on the
implicit presence of BUG code.
2) find and fix any C files that were consuming kernel.h and hence
relying on implicitly getting some/all BUG code.
3) Move the BUG related code living in kernel.h to <linux/bug.h>
4) remove the asm/bug.h from kernel.h to finally break the chain.
During development, the order was more like 3-4, build-test, 1-2. But
to ensure that git history for bisect doesn't get needless build
failures introduced, the commits have been reorderd to fix the problem
areas in advance.
[1] https://lkml.org/lkml/2012/1/3/90
[2] https://lkml.org/lkml/2012/1/17/414"
Fix up conflicts (new radeon file, reiserfs header cleanups) as per Paul
and linux-next.
* tag 'bug-for-3.4' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux:
kernel.h: doesn't explicitly use bug.h, so don't include it.
bug: consolidate BUILD_BUG_ON with other bug code
BUG: headers with BUG/BUG_ON etc. need linux/bug.h
bug.h: add include of it to various implicit C users
lib: fix implicit users of kernel.h for TAINT_WARN
spinlock: macroize assert_spin_locked to avoid bug.h dependency
x86: relocate get/set debugreg fcns to include/asm/debugreg.
Dave found:
| During bootup, I now have 162 messages like this..
| [ 0.227346] MSR0000001b: 00000000fee00900
| [ 0.227465] MSR00000021: 0000000000000001
| [ 0.227584] MSR0000002a: 00000000c1c81400
|
| commit 21c3fcf3e3 looks suspect.
| It claims that it will only print these out if show_msr= is
| passed, but that doesn't seem to be the case.
Fix it by changing to the version that checks the index.
Reported-and-tested-by: Dave Jones <davej@redhat.com>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Link: http://lkml.kernel.org/r/1332477103-4595-1-git-send-email-yinghai@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull x86/fpu changes from Ingo Molnar.
* 'x86-fpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
i387: Split up <asm/i387.h> into exported and internal interfaces
i387: Uninline the generic FP helpers that we expose to kernel modules
Since we already have a debugreg.h header file, move the
assoc. get/set functions to it. In addition to it being the
logical home for them, it has a secondary advantage. The
functions that are moved use BUG(). So we really need to
have linux/bug.h in scope. But asm/processor.h is used about
600 times, vs. only about 15 for debugreg.h -- so adding bug.h
to the latter reduces the amount of time we'll be processing
it during a compile.
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: "H. Peter Anvin" <hpa@zytor.com>
While various modules include <asm/i387.h> to get access to things we
actually *intend* for them to use, most of that header file was really
pretty low-level internal stuff that we really don't want to expose to
others.
So split the header file into two: the small exported interfaces remain
in <asm/i387.h>, while the internal definitions that are only used by
core architecture code are now in <asm/fpu-internal.h>.
The guiding principle for this was to expose functions that we export to
modules, and leave them in <asm/i387.h>, while stuff that is used by
task switching or was marked GPL-only is in <asm/fpu-internal.h>.
The fpu-internal.h file could be further split up too, especially since
arch/x86/kvm/ uses some of the remaining stuff for its module. But that
kvm usage should probably be abstracted out a bit, and at least now the
internal FPU accessor functions are much more contained. Even if it
isn't perhaps as contained as it _could_ be.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/alpine.LFD.2.02.1202211340330.5354@i5.linux-foundation.org
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Instead of exporting the very low-level internals of the FPU state
save/restore code (ie things like 'fpu_owner_task'), we should export
the higher-level interfaces.
Inlining these things is pointless anyway: sure, sometimes the end
result is small, but while 'stts()' can result in just three x86
instructions, those are not cheap instructions (writing %cr0 is a
serializing instruction and a very slow one at that).
So the overhead of a function call is not noticeable, and we really
don't want random modules mucking about with our internal state save
logic anyway.
So this unexports 'fpu_owner_task', and instead uninlines and exports
the actual functions that modules can use: fpu_kernel_begin/end() and
unlazy_fpu().
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/alpine.LFD.2.02.1202211339590.5354@i5.linux-foundation.org
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
(And define it properly for x86-32, which had its 'current_task'
declaration in separate from x86-64)
Bitten by my dislike for modules on the machines I use, and the fact
that apparently nobody else actually wanted to test the patches I sent
out.
Snif. Nobody else cares.
Anyway, we probably should uninline the 'kernel_fpu_begin()' function
that is what modules actually use and that references this, but this is
the minimal fix for now.
Reported-by: Josh Boyer <jwboyer@gmail.com>
Reported-and-tested-by: Jongman Heo <jongman.heo@samsung.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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>
Found out that show_msr=<cpus> is broken, when I asked a
user to use it to capture debug info about broken MTRR's
whose MTRR settings are probably different between CPUs.
Only the first CPUs MSRs are printed, but that is not
enough to track down the suspected bug.
For years we called print_cpu_msr from print_cpu_info(),
but this commit:
| commit 2eaad1fddd
| Author: Mike Travis <travis@sgi.com>
| Date: Thu Dec 10 17:19:36 2009 -0800
|
| x86: Limit the number of processor bootup messages
removed the print_cpu_info() call from all APs.
Put it back - it will only print MSRs when the user
specifically requests them via show_msr=<cpus>.
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Cc: Mike Travis <travis@sgi.com>
Link: http://lkml.kernel.org/r/1329069237-11483-1-git-send-email-yinghai@kernel.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
* 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (39 commits)
perf tools: Fix compile error on x86_64 Ubuntu
perf report: Fix --stdio output alignment when --showcpuutilization used
perf annotate: Get rid of field_sep check
perf annotate: Fix usage string
perf kmem: Fix a memory leak
perf kmem: Add missing closedir() calls
perf top: Add error message for EMFILE
perf test: Change type of '-v' option to INCR
perf script: Add missing closedir() calls
tracing: Fix compile error when static ftrace is enabled
recordmcount: Fix handling of elf64 big-endian objects.
perf tools: Add const.h to MANIFEST to make perf-tar-src-pkg work again
perf tools: Add support for guest/host-only profiling
perf kvm: Do guest-only counting by default
perf top: Don't update total_period on process_sample
perf hists: Stop using 'self' for struct hist_entry
perf hists: Rename total_session to total_period
x86: Add counter when debug stack is used with interrupts enabled
x86: Allow NMIs to hit breakpoints in i386
x86: Keep current stack in NMI breakpoints
...
Mathieu Desnoyers pointed out a case that can cause issues with
NMIs running on the debug stack:
int3 -> interrupt -> NMI -> int3
Because the interrupt changes the stack, the NMI will not see that
it preempted the debug stack. Looking deeper at this case,
interrupts only happen when the int3 is from userspace or in
an a location in the exception table (fixup).
userspace -> int3 -> interurpt -> NMI -> int3
All other int3s that happen in the kernel should be processed
without ever enabling interrupts, as the do_trap() call will
panic the kernel if it is called to process any other location
within the kernel.
Adding a counter around the sections that enable interrupts while
using the debug stack allows the NMI to also check that case.
If the NMI sees that it either interrupted a task using the debug
stack or the debug counter is non-zero, then it will have to
change the IDT table to make the int3 not change stacks (which will
corrupt the stack if it does).
Note, I had to move the debug_usage functions out of processor.h
and into debugreg.h because of the static inlined functions to
inc and dec the debug_usage counter. __get_cpu_var() requires
smp.h which includes processor.h, and would fail to build.
Link: http://lkml.kernel.org/r/1323976535.23971.112.camel@gandalf.stny.rr.com
Reported-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: H. Peter Anvin <hpa@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Paul Turner <pjt@google.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
We want to allow NMI handlers to have breakpoints to be able to
remove stop_machine from ftrace, kprobes and jump_labels. But if
an NMI interrupts a current breakpoint, and then it triggers a
breakpoint itself, it will switch to the breakpoint stack and
corrupt the data on it for the breakpoint processing that it
interrupted.
Instead, have the NMI check if it interrupted breakpoint processing
by checking if the stack that is currently used is a breakpoint
stack. If it is, then load a special IDT that changes the IST
for the debug exception to keep the same stack in kernel context.
When the NMI is done, it puts it back.
This way, if the NMI does trigger a breakpoint, it will keep
using the same stack and not stomp on the breakpoint data for
the breakpoint it interrupted.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Several fields in struct cpuinfo_x86 were not defined for the
!SMP case, likely to save space. However, those fields still
have some meaning for UP, and keeping them allows some #ifdef
removal from other files. The additional size of the UP kernel
from this change is not significant enough to worry about
keeping up the distinction:
text data bss dec hex filename
4737168 506459 972040 6215667 5ed7f3 vmlinux.o.before
4737444 506459 972040 6215943 5ed907 vmlinux.o.after
for a difference of 276 bytes for an example UP config.
If someone wants those 276 bytes back badly then it should
be implemented in a cleaner way.
Signed-off-by: Kevin Winchester <kjwinchester@gmail.com>
Cc: Steffen Persvold <sp@numascale.com>
Link: http://lkml.kernel.org/r/1324428742-12498-1-git-send-email-kjwinchester@gmail.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
* 'x86-rdrand-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86, random: Verify RDRAND functionality and allow it to be disabled
x86, random: Architectural inlines to get random integers with RDRAND
random: Add support for architectural random hooks
Fix up trivial conflicts in drivers/char/random.c: the architectural
random hooks touched "get_random_int()" that was simplified to use MD5
and not do the keyptr thing any more (see commit 6e5714eaf7: "net:
Compute protocol sequence numbers and fragment IDs using MD5").
* 'x86-cpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86, amd: Include linux/elf.h since we use stuff from asm/elf.h
x86: cache_info: Update calculation of AMD L3 cache indices
x86: cache_info: Kill the atomic allocation in amd_init_l3_cache()
x86: cache_info: Kill the moronic shadow struct
x86: cache_info: Remove bogus free of amd_l3_cache data
x86, amd: Include elf.h explicitly, prepare the code for the module.h split
x86-32, amd: Move va_align definition to unbreak 32-bit build
x86, amd: Move BSP code to cpu_dev helper
x86: Add a BSP cpu_dev helper
x86, amd: Avoid cache aliasing penalties on AMD family 15h
If the CPU declares that RDRAND is available, go through a guranteed
reseed sequence, and make sure that it is actually working (producing
data.) If it does not, disable the CPU feature flag.
Allow RDRAND to be disabled on the command line (as opposed to at
compile time) for a user who has special requirements with regards to
random numbers.
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "Theodore Ts'o" <tytso@mit.edu>
