Re: CVS commit: src/sys/kern

[Maxime Villard <max%m00nbsd.net@localhost>]

Le 08/12/2019 à 14:22, Martin Husemann a écrit :
> On Sun, Dec 08, 2019 at 12:58:20PM +0100, Maxime Villard wrote:
> > kMSan has special constraints which, in this specific case, come down to: each
> > function called from a KCOV instrumentation callback must be a static inline
> > tagged with __nomsan.
> >
> > This was not the case with the updated in_interrupt(), but also still isn't the
> > case with the lwp_getspecific() call, which will have to be dropped.
>
> This does not sound like a good reason to introduce MD code in sys/kern to
> me. Could should not be made worse to deal with sanitizer restrictions.
>
> Are there any alternatives?

The clean way of doing this is having an MD kcov.h included from subr_kcov.c,
like kASan.

However, I expect that we will want a per-lwp kcov flag to indicate the current
context (in exception, in interrupt, in nmi, etc), and when that happens, I
don't expect that we will need in_interrupt anymore.

Therefore, I wouldn't bother adding kcov.h headers, and rolling back to the
previous version of in_interrupt for now is fine, considering that kcov
currently has no use outside of amd64.