diff options
| author | Ingo Molnar <mingo@kernel.org> | 2015-10-06 10:56:54 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2015-10-06 10:56:54 +0200 |
| commit | 38a413cbc2b2834683b21823d964bc2d2f0abb82 (patch) | |
| tree | 2c62753bef5068ca9a34f13beee142304d028ec0 /arch/x86/entry | |
| parent | 55696b1f664e52b3036f21631f9c2247b667f587 (diff) | |
| parent | 9ffecb10283508260936b96022d4ee43a7798b4c (diff) | |
Merge tag 'v4.3-rc3' into x86/mm, to pick up fixes before applying new changes
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/entry')
| -rw-r--r-- | arch/x86/entry/entry_64.S | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index d3033183ed70..055a01de7c8d 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -1128,7 +1128,18 @@ END(error_exit) /* Runs on exception stack */ ENTRY(nmi) + /* + * Fix up the exception frame if we're on Xen. + * PARAVIRT_ADJUST_EXCEPTION_FRAME is guaranteed to push at most + * one value to the stack on native, so it may clobber the rdx + * scratch slot, but it won't clobber any of the important + * slots past it. + * + * Xen is a different story, because the Xen frame itself overlaps + * the "NMI executing" variable. + */ PARAVIRT_ADJUST_EXCEPTION_FRAME + /* * We allow breakpoints in NMIs. If a breakpoint occurs, then * the iretq it performs will take us out of NMI context. @@ -1179,9 +1190,12 @@ ENTRY(nmi) * we don't want to enable interrupts, because then we'll end * up in an awkward situation in which IRQs are on but NMIs * are off. + * + * We also must not push anything to the stack before switching + * stacks lest we corrupt the "NMI executing" variable. */ - SWAPGS + SWAPGS_UNSAFE_STACK cld movq %rsp, %rdx movq PER_CPU_VAR(cpu_current_top_of_stack), %rsp |