linux-kernel - Re: [PATCH v3 27/46] kmsan: instrumentation.h: add instrumentation_begin_with

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Message-ID: <CAG_fn=WhNZ8+7RXvr_2nGa-mCpLYxBK=cw3wFg6bxOqgXTOH0A@mail.gmail.com>
Date:   Mon, 16 May 2022 13:49:16 +0200
From:   Alexander Potapenko <glider@...gle.com>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     Alexander Viro <viro@...iv.linux.org.uk>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Andrey Konovalov <andreyknvl@...gle.com>,
        Andy Lutomirski <luto@...nel.org>,
        Arnd Bergmann <arnd@...db.de>, Borislav Petkov <bp@...en8.de>,
        Christoph Hellwig <hch@....de>,
        Christoph Lameter <cl@...ux.com>,
        David Rientjes <rientjes@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Ilya Leoshkevich <iii@...ux.ibm.com>,
        Ingo Molnar <mingo@...hat.com>, Jens Axboe <axboe@...nel.dk>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Kees Cook <keescook@...omium.org>,
        Marco Elver <elver@...gle.com>,
        Mark Rutland <mark.rutland@....com>,
        Matthew Wilcox <willy@...radead.org>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Pekka Enberg <penberg@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Petr Mladek <pmladek@...e.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Vegard Nossum <vegard.nossum@...cle.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        kasan-dev <kasan-dev@...glegroups.com>,
        Linux Memory Management List <linux-mm@...ck.org>,
        Linux-Arch <linux-arch@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 27/46] kmsan: instrumentation.h: add instrumentation_begin_with_regs()

On Wed, Apr 27, 2022 at 3:28 PM Thomas Gleixner <tglx@...utronix.de> wrote:
>
> On Tue, Apr 26 2022 at 18:42, Alexander Potapenko wrote:
> > +void kmsan_instrumentation_begin(struct pt_regs *regs)
> > +{
> > +     struct kmsan_context_state *state = &kmsan_get_context()->cstate;
> > +
> > +     if (state)
> > +             __memset(state, 0, sizeof(struct kmsan_context_state));
>
>   sizeof(*state) please
>
> > +     if (!kmsan_enabled || !regs)
> > +             return;
>
> Why has state to be cleared when kmsan is not enabled and how do you end up
> with regs == NULL here?
>
> Thanks,
>
>         tglx
>
> --
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As discussed in another thread, I'll be dropping this patch in favor
of the new kmsan_unpoison_entry_regs().

I'll also ensure I consistently use sizeof(*pointer) where applicable.

Regarding regs==NULL, this is actually not a thing.

-- 
Alexander Potapenko
Software Engineer

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