lkml.org 
[lkml]   [2021]   [Dec]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v1 04/12] x86/mce: Remove noinstr annotation from mce_setup()
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
>

\
 
 \ /
  Last update: 2021-12-09 13:17    [W:0.148 / U:0.296 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site