Messages in this thread | | | Date | Thu, 9 Dec 2021 13:16:56 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH v1 04/12] x86/mce: Remove noinstr annotation from mce_setup() |
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On Wed, Dec 08, 2021 at 12:13:35PM +0100, Borislav Petkov wrote: > From: Borislav Petkov <bp@suse.de> > > Instead, sandwitch around the call which is done in noinstr context and > mark the caller - mce_gather_info() - as noinstr. > > Signed-off-by: Borislav Petkov <bp@suse.de> > --- > arch/x86/kernel/cpu/mce/core.c | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c > index 87a277fc80b4..f61f14faa532 100644 > --- a/arch/x86/kernel/cpu/mce/core.c > +++ b/arch/x86/kernel/cpu/mce/core.c > @@ -127,7 +127,7 @@ static struct irq_work mce_irq_work; > BLOCKING_NOTIFIER_HEAD(x86_mce_decoder_chain); > > /* Do initial initialization of a struct mce */ > -noinstr void mce_setup(struct mce *m) > +void mce_setup(struct mce *m) > { > memset(m, 0, sizeof(struct mce)); > m->cpu = m->extcpu = smp_processor_id(); > @@ -430,9 +430,15 @@ static noinstr void mce_wrmsrl(u32 msr, u64 v) > * check into our "mce" struct so that we can use it later to assess > * the severity of the problem as we read per-bank specific details. > */ > -static inline void mce_gather_info(struct mce *m, struct pt_regs *regs) > +static noinstr void mce_gather_info(struct mce *m, struct pt_regs *regs) > { > + /* > + * Enable instrumentation around mce_setup() which calls external > + * facilities.
Yeah, that's what it does; but *why* is that correct? I'm thinking we're well past the exception entry code and are only using noinstr as a means to limit the amount of code in the MCE handler?
> + */ > + instrumentation_begin(); > mce_setup(m); > + instrumentation_end(); > > m->mcgstatus = mce_rdmsrl(MSR_IA32_MCG_STATUS); > if (regs) { > -- > 2.29.2 >
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