Re: [PATCH 39/43] x86: kmsan: handle register passing from uninstrumented code

[Thomas Gleixner]

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 +++

> @@ -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);

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

Thanks,

        tglx