Re: [PATCH 3/3] x86/mm, tracing: Fix CR2 corruption

[Steven Rostedt]

On Wed, 3 Jul 2019 13:27:09 -0700
Andy Lutomirski <luto@xxxxxxxxxx> 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.

-- Steve