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7fbb98c5cb
linux/arch/x86/kernel
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Steven Rostedt 7fbb98c5cb x86: Save cr2 in NMI in case NMIs take a page fault 
Avi Kivity reported that page faults in NMIs could cause havic if
the NMI preempted another page fault handler:

   The recent changes to NMI allow exceptions to take place in NMI
   handlers, but I think that a #PF (say, due to access to vmalloc space)
   is still problematic.  Consider the sequence

    #PF  (cr2 set by processor)
      NMI
        ...
        #PF (cr2 clobbered)
          do_page_fault()
          IRET
        ...
        IRET
      do_page_fault()
        address = read_cr2()

   The last line reads the overwritten cr2 value.

Originally I wrote a patch to solve this by saving the cr2 on the stack.
Brian Gerst suggested to save it in the r12 register as both r12 and rbx
are saved by the do_nmi handler as required by the C standard. But rbx
is already used for saving if swapgs needs to be run on exit of the NMI
handler.

Link: http://lkml.kernel.org/r/4FBB8C40.6080304@redhat.com
Link: http://lkml.kernel.org/r/1337763411.13348.140.camel@gandalf.stny.rr.com

Reported-by: Avi Kivity <avi@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Suggested-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2012-06-07 10:21:21 -04:00
..
acpi Merge branch 'x86-trampoline-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-05-29 20:14:53 -07:00
apic x86/debug: Add KERN_<LEVEL> to bare printks, convert printks to pr_<level> 2012-06-06 09:17:22 +02:00
cpu x86/debug: Add KERN_<LEVEL> to bare printks, convert printks to pr_<level> 2012-06-06 09:17:22 +02:00
.gitignore
alternative.c x86/debug: Add KERN_<LEVEL> to bare printks, convert printks to pr_<level> 2012-06-06 09:17:22 +02:00
amd_gart_64.c X86 & IA64: adapt for dma_map_ops changes 2012-03-28 16:36:31 +02:00
amd_nb.c x86/debug: Add KERN_<LEVEL> to bare printks, convert printks to pr_<level> 2012-06-06 09:17:22 +02:00
apb_timer.c Merge branch 'timers-clocksource-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2011-07-23 10:34:47 -07:00
aperture_64.c memblock, x86: Replace memblock_x86_reserve/free_range() with generic ones 2011-07-14 11:47:53 -07:00
apm_32.c x86/debug: Add KERN_<LEVEL> to bare printks, convert printks to pr_<level> 2012-06-06 09:17:22 +02:00
asm-offsets_32.c x86: Generate system call tables and unistd_*.h from tables 2011-11-17 13:35:37 -08:00
asm-offsets_64.c x32: If configured, add x32 system calls to system call tables 2012-02-20 12:52:06 -08:00
asm-offsets.c x86, efi: EFI boot stub support 2011-12-12 14:26:10 -08:00
audit_64.c
bootflag.c
check.c x86: kernel/check.c simple_strtoul cleanup 2012-05-15 15:36:41 -07:00
cpuid.c Disintegrate asm/system.h for X86 2012-03-28 18:11:12 +01:00
crash_dump_32.c x86: remove the second argument of k[un]map_atomic() 2012-03-20 21:48:15 +08:00
crash_dump_64.c
crash.c x86, nmi: Wire up NMI handlers to new routines 2011-10-10 06:56:57 +02:00
devicetree.c irq_domain/x86: Convert x86 (embedded) to use common irq_domain 2012-02-23 14:37:47 -07:00
doublefault_32.c
dumpstack_32.c x86/debug: Add KERN_<LEVEL> to bare printks, convert printks to pr_<level> 2012-06-06 09:17:22 +02:00
dumpstack_64.c x86/debug: Add KERN_<LEVEL> to bare printks, convert printks to pr_<level> 2012-06-06 09:17:22 +02:00
dumpstack.c x86/debug: Add KERN_<LEVEL> to bare printks, convert printks to pr_<level> 2012-06-06 09:17:22 +02:00
e820.c x86: print e820 physical addresses consistently with other parts of kernel 2012-05-29 16:22:20 -07:00
early_printk.c Merge branch 'x86-platform-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-01-11 19:13:40 -08:00
early-quirks.c
entry_32.S x86: get rid of calling do_notify_resume() when returning to kernel mode 2012-06-01 13:01:51 -04:00
entry_64.S x86: Save cr2 in NMI in case NMIs take a page fault 2012-06-07 10:21:21 -04:00
ftrace.c ftrace: Use breakpoint method to update ftrace caller 2012-05-31 23:12:19 -04:00
head32.c x86, realmode: Move ACPI wakeup to unified realmode code 2012-05-08 11:46:05 -07:00
head64.c x86, realmode: Move ACPI wakeup to unified realmode code 2012-05-08 11:46:05 -07:00
head_32.S Merge branch 'x86-trampoline-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-05-29 20:14:53 -07:00
head_64.S Merge branch 'x86-trampoline-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-05-29 20:14:53 -07:00
head.c memblock, x86: Replace memblock_x86_reserve/free_range() with generic ones 2011-07-14 11:47:53 -07:00
hpet.c x86: hpet: Fix copy-and-paste mistake in earlier change 2012-05-25 15:32:29 +02:00
hw_breakpoint.c
i386_ksyms_32.c
i387.c x86: replace percpu_xxx funcs with this_cpu_xxx 2012-05-14 14:15:31 -07:00
i8237.c
i8253.c x86: Use common i8253 clockevent 2011-07-01 10:37:14 +02:00
i8259.c Disintegrate asm/system.h for X86 2012-03-28 18:11:12 +01:00
io_delay.c
ioport.c
irq_32.c x86: Use common threadinfo allocator 2012-05-08 14:08:44 +02:00
irq_64.c x86: Add stack top margin for stack overflow checking 2011-12-07 09:27:11 +01:00
irq_work.c
irq.c x86/debug: Add KERN_<LEVEL> to bare printks, convert printks to pr_<level> 2012-06-06 09:17:22 +02:00
irqinit.c Merge branch 'x86-cleanups-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-03-29 18:21:35 -07:00
jump_label.c jump_label, x86: Fix section mismatch 2011-12-06 20:41:02 +01:00
kdebugfs.c simple_open: automatically convert to simple_open() 2012-04-05 15:25:50 -07:00
kgdb.c KGDB/KDB regression fixes 2012-04-04 17:26:08 -07:00
kprobes-common.h x86/kprobes: Split out optprobe related code to kprobes-opt.c 2012-03-06 09:49:49 +01:00
kprobes-opt.c x86/kprobes: Split out optprobe related code to kprobes-opt.c 2012-03-06 09:49:49 +01:00
kprobes.c x86: Avoid double stack traces with show_regs() 2012-05-09 11:44:42 +02:00
kvm.c KVM: Do not take reference to mm during async #PF 2012-05-06 15:00:02 +03:00
kvmclock.c kvmclock: remove unneeded EXPORT macro 2012-04-08 12:49:54 +03:00
ldt.c Disintegrate asm/system.h for X86 2012-03-28 18:11:12 +01:00
machine_kexec_32.c Disintegrate asm/system.h for X86 2012-03-28 18:11:12 +01:00
machine_kexec_64.c
Makefile Merge branch 'x86-trampoline-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-05-29 20:14:53 -07:00
microcode_amd.c x86, microcode: Ensure that module is only loaded on supported AMD CPUs 2012-04-13 11:51:05 +02:00
microcode_core.c x86, microcode: microcode_core.c simple_strtoul cleanup 2012-05-07 11:36:49 -07:00
microcode_intel.c x86/microcode: Ensure that module is only loaded on supported Intel CPUs 2012-05-07 14:37:14 +02:00
mmconf-fam10h_64.c
module.c x86/debug: Add KERN_<LEVEL> to bare printks, convert printks to pr_<level> 2012-06-06 09:17:22 +02:00
mpparse.c Merge branch 'x86-trampoline-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-05-29 20:14:53 -07:00
msr.c Disintegrate asm/system.h for X86 2012-03-28 18:11:12 +01:00
nmi_selftest.c Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-05-23 10:21:19 -07:00
nmi.c x86: Reset the debug_stack update counter 2012-05-31 23:12:20 -04:00
paravirt_patch_32.c
paravirt_patch_64.c
paravirt-spinlocks.c
paravirt.c x86: replace percpu_xxx funcs with this_cpu_xxx 2012-05-14 14:15:31 -07:00
pci-calgary_64.c x86/debug: Add KERN_<LEVEL> to bare printks, convert printks to pr_<level> 2012-06-06 09:17:22 +02:00
pci-dma.c X86: integrate CMA with DMA-mapping subsystem 2012-05-21 15:09:38 +02:00
pci-iommu_table.c arch/x86/kernel/pci-iommu_table.c: Convert sprintf_symbol to %pS 2011-05-10 10:21:35 +02:00
pci-nommu.c X86: integrate CMA with DMA-mapping subsystem 2012-05-21 15:09:38 +02:00
pci-swiotlb.c X86 & IA64: adapt for dma_map_ops changes 2012-03-28 16:36:31 +02:00
pcspeaker.c
probe_roms.c x86: Include probe_roms.h in probe_roms.c 2012-03-08 10:57:35 +01:00
process_32.c Merge branch 'x86-fpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-05-23 10:59:07 -07:00
process_64.c x86/debug: Add KERN_<LEVEL> to bare printks, convert printks to pr_<level> 2012-06-06 09:17:22 +02:00
process.c x86/debug: Add KERN_<LEVEL> to bare printks, convert printks to pr_<level> 2012-06-06 09:17:22 +02:00
ptrace.c x86, x32, ptrace: Remove PTRACE_ARCH_PRCTL for x32 2012-06-01 13:54:21 -07:00
pvclock.c
quirks.c x86, amd: Fix up numa_node information for AMD CPU family 15h model 0-0fh northbridge functions 2011-12-05 18:13:11 +01:00
reboot_fixups_32.c
reboot.c x86/debug: Add KERN_<LEVEL> to bare printks, convert printks to pr_<level> 2012-06-06 09:17:22 +02:00
relocate_kernel_32.S kexec, x86: Fix incorrect jump back address if not preserving context 2011-07-21 11:19:28 +02:00
relocate_kernel_64.S kexec, x86: Fix incorrect jump back address if not preserving context 2011-07-21 11:19:28 +02:00
resource.c
rtc.c x86/rtc, mrst: Don't register a platform RTC device for for Intel MID platforms 2011-12-05 17:09:21 +01:00
setup_percpu.c percpu, x86: don't use PMD_SIZE as embedded atom_size on 32bit 2012-05-08 09:42:18 -07:00
setup.c Merge branch 'x86-trampoline-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-05-29 20:14:53 -07:00
signal.c x86/debug: Add KERN_<LEVEL> to bare printks, convert printks to pr_<level> 2012-06-06 09:17:22 +02:00
smp.c x86/reboot: Update nonmi_ipi parameter 2012-05-14 11:49:38 +02:00
smpboot.c x86/debug: Add KERN_<LEVEL> to bare printks, convert printks to pr_<level> 2012-06-06 09:17:22 +02:00
stacktrace.c x86: Swap save_stack_trace_regs parameters 2011-06-14 22:48:51 -04:00
step.c x86-64: Add user_64bit_mode paravirt op 2011-08-04 16:13:49 -07:00
sys_i386_32.c
sys_x86_64.c Merge branch 'x86-x32-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-03-29 18:12:23 -07:00
syscall_32.c x86, syscall: Re-fix typo in comment 2011-11-18 16:25:07 -08:00
syscall_64.c x32: If configured, add x32 system calls to system call tables 2012-02-20 12:52:06 -08:00
tboot.c x86, realmode: fixes compilation issue in tboot.c 2012-05-08 15:04:27 -07:00
tce_64.c Disintegrate asm/system.h for X86 2012-03-28 18:11:12 +01:00
test_nx.c x86: Eliminate various 'set but not used' warnings 2011-05-21 19:10:33 +02:00
test_rodata.c x86, extable: Remove open-coded exception table entries in arch/x86/kernel/test_rodata.c 2012-04-20 13:51:38 -07:00
time.c MCA: delete all remaining traces of microchannel bus support. 2012-05-17 19:06:13 -04:00
tls.c Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-03-29 14:28:26 -07:00
tls.h
topology.c x86: Fix files explicitly requiring export.h for EXPORT_SYMBOL/THIS_MODULE 2011-10-31 19:30:35 -04:00
traps.c x86/debug: Add KERN_<LEVEL> to bare printks, convert printks to pr_<level> 2012-06-06 09:17:22 +02:00
tsc_sync.c x86/tsc: Reduce the TSC sync check time for core-siblings 2012-02-22 11:49:40 +01:00
tsc.c x86/debug: Add KERN_<LEVEL> to bare printks, convert printks to pr_<level> 2012-06-06 09:17:22 +02:00
uprobes.c uprobes/core: Handle breakpoint and singlestep exceptions 2012-03-14 07:41:36 +01:00
verify_cpu.S
vm86_32.c x86/debug: Add KERN_<LEVEL> to bare printks, convert printks to pr_<level> 2012-06-06 09:17:22 +02:00
vmlinux.lds.S x86, realmode: Move ACPI wakeup to unified realmode code 2012-05-08 11:46:05 -07:00
vsmp_64.c x86/vsmp: Fix number of CPUs when vsmp is disabled 2012-05-14 14:42:33 +02:00
vsyscall_64.c x86/debug: Add KERN_<LEVEL> to bare printks, convert printks to pr_<level> 2012-06-06 09:17:22 +02:00
vsyscall_emu_64.S x86-64: Rework vsyscall emulation and add vsyscall= parameter 2011-08-10 19:26:46 -05:00
vsyscall_trace.h x86-64: Add vsyscall:emulate_vsyscall trace event 2011-08-04 16:13:53 -07:00
x86_init.c x86/apic: Replace io_apic_ops with x86_io_apic_ops. 2012-05-01 14:50:09 -04:00
x8664_ksyms_64.c
xsave.c x86/debug: Add KERN_<LEVEL> to bare printks, convert printks to pr_<level> 2012-06-06 09:17:22 +02:00