Messages in this thread | | | From | Andy Lutomirski <> | Date | Wed, 3 Jul 2019 15:26:47 -0700 | Subject | Re: [PATCH 3/3] x86/mm, tracing: Fix CR2 corruption |
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On Wed, Jul 3, 2019 at 3:01 PM Peter Zijlstra <peterz@infradead.org> wrote: > > On Wed, Jul 03, 2019 at 01:27:09PM -0700, Andy Lutomirski wrote: > > On Wed, Jul 3, 2019 at 3:28 AM root <peterz@infradead.org> wrote: > > > > @@ -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? > > > > - CALL_enter_from_user_mode > > > ret > > > > > > .Lerror_entry_done: > > > - TRACE_IRQS_OFF > > > ret > > > > > > /* > > Did you perchance mean to complain about the .Lerror_entry_done one?
Yes, duh.
I would suggest compiling with DEBUG_LOCKDEP and running perf and the x86 selftests. IIRC that's what catches most of the IRQ flag tracing errors.
> > Because I'm not seeing how the one before CALL_enter_from_user_mode can > ever be from-kernel. > > But yes, that .Lerror_entry_done one looks fishy.
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