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SubjectRe: [PATCH 3/3] x86/mm, tracing: Fix CR2 corruption
On Wed, Jul 03, 2019 at 04:47:01PM -0400, Steven Rostedt wrote:
> On Wed, 3 Jul 2019 13:27:09 -0700
> Andy Lutomirski <luto@kernel.org> wrote:
>
>
> > > @@ -1180,10 +1189,10 @@ idtentry xenint3 do_int3 has_error_co
> > > #endif
> > >
> > > idtentry general_protection do_general_protection has_error_code=1
> > > -idtentry page_fault do_page_fault has_error_code=1
> > > +idtentry page_fault do_page_fault has_error_code=1 read_cr2=1
> > >
> > > #ifdef CONFIG_KVM_GUEST
> > > -idtentry async_page_fault do_async_page_fault has_error_code=1
> > > +idtentry async_page_fault do_async_page_fault has_error_code=1 read_cr2=1
> > > #endif
> > >
> > > #ifdef CONFIG_X86_MCE
> > > @@ -1338,18 +1347,9 @@ ENTRY(error_entry)
> > > movq %rax, %rsp /* switch stack */
> > > ENCODE_FRAME_POINTER
> > > pushq %r12
> > > -
> > > - /*
> > > - * We need to tell lockdep that IRQs are off. We can't do this until
> > > - * we fix gsbase, and we should do it before enter_from_user_mode
> > > - * (which can take locks).
> > > - */
> > > - TRACE_IRQS_OFF
> >
> > This hunk looks wrong. Am I missing some other place that handles the
> > case where we enter from kernel mode and IRQs were on?
>
> Yeah, looks like we might be missing a TRACE_IRQS_OFF from the
> from_usermode_stack_switch path.

Oh bugger, there's a second error_entry call.

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