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SubjectRe: [PATCH 39/43] x86: kmsan: handle register passing from uninstrumented code
On Fri, Dec 17, 2021 at 10:51 PM Thomas Gleixner <tglx@linutronix.de> wrote:
>
> Alexander,
>
> On Tue, Dec 14 2021 at 17:20, Alexander Potapenko wrote:
> > When calling KMSAN-instrumented functions from non-instrumented
> > functions, function parameters may not be initialized properly, leading
> > to false positive reports. In particular, this happens all the time when
> > calling interrupt handlers from `noinstr` IDT entries.
> >
> > Fortunately, x86 code has instrumentation_begin() and
>
> It's not only x86 code:
> > kernel/entry/common.c | 3 +++

Shall this bit go into a separate patch?

> > @@ -76,6 +77,7 @@ __visible noinstr void do_syscall_64(struct pt_regs *regs, int nr)
> > nr = syscall_enter_from_user_mode(regs, nr);
> >
> > instrumentation_begin();
> > + kmsan_instrumentation_begin(regs);
>
> Can we please make this something like:
>
> instrumentation_begin_at_entry(regs);

Fine, will do.
Do you think it would make sense to hide it inside
instrumentation_begin(), or is it ok to have both macros follow each
other?

> or some other sensible name which hides that kmsan gunk and avoids to
> touch all of this again when KFOOSAN comes around?
>
> Thanks,
>
> tglx
>
>
>


--
Alexander Potapenko
Software Engineer

Google Germany GmbH
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