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From:   Alexander Potapenko <glider@google.com>
Date:   Wed, 19 Oct 2022 14:44:28 -0700
Message-ID: <CAG_fn=WF1i+JL_E-7wWEpgtxRNssm_vZx+hqGh_pYDuX1WGPVQ@mail.gmail.com>
Subject: Re: [PATCH v7 18/43] instrumented.h: add KMSAN support
To:     youling 257 <youling257@gmail.com>
Cc:     Marco Elver <elver@google.com>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Alexei Starovoitov <ast@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Andrey Konovalov <andreyknvl@google.com>,
        Andy Lutomirski <luto@kernel.org>,
        Arnd Bergmann <arnd@arndb.de>, Borislav Petkov <bp@alien8.de>,
        Christoph Hellwig <hch@lst.de>,
        Christoph Lameter <cl@linux.com>,
        David Rientjes <rientjes@google.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Eric Biggers <ebiggers@kernel.org>,
        Eric Dumazet <edumazet@google.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        Ilya Leoshkevich <iii@linux.ibm.com>,
        Ingo Molnar <mingo@redhat.com>, Jens Axboe <axboe@kernel.dk>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>,
        Kees Cook <keescook@chromium.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Matthew Wilcox <willy@infradead.org>,
        "Michael S. Tsirkin" <mst@redhat.com>,
        Pekka Enberg <penberg@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Petr Mladek <pmladek@suse.com>,
        Stephen Rothwell <sfr@canb.auug.org.au>,
        Steven Rostedt <rostedt@goodmis.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Vasily Gorbik <gor@linux.ibm.com>,
        Vegard Nossum <vegard.nossum@oracle.com>,
        Vlastimil Babka <vbabka@suse.cz>, kasan-dev@googlegroups.com,
        linux-mm@kvack.org, linux-arch@vger.kernel.org,
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On Wed, Oct 19, 2022 at 1:07 PM youling 257 <youling257@gmail.com> wrote:
>
> That is i did,i already test, remove "u64 __tmp=E2=80=A6kmsan_unpoison_me=
mory", no help.
> i only remove kmsan_copy_to_user, fix my issue.

Do you have any profiling results that can help pinpoint functions
that are affected by this change?
Also, am I getting it right you are building x86 Android?


> 2022-10-20 4:00 GMT+08:00, Marco Elver <elver@google.com>:
> > On Thu, Oct 20, 2022 at 03:29AM +0800, youling 257 wrote:
> > [...]
> >> > What arch?
> >> > If x86, can you try to revert only the change to
> >> > instrument_get_user()? (I wonder if the u64 conversion is causing
> >> > issues.)
> >> >
> >> arch x86, this's my revert,
> >> https://github.com/youling257/android-mainline/commit/401cbfa61cbfc20c=
87a5be8e2dda68ac5702389f
> >> i tried different revert, have to remove kmsan_copy_to_user.
> >
> > There you reverted only instrument_put_user() - does it fix the issue?
> >
> > If not, can you try only something like this (only revert
> > instrument_get_user()):
> >
> > diff --git a/include/linux/instrumented.h b/include/linux/instrumented.=
h
> > index 501fa8486749..dbe3ec38d0e6 100644
> > --- a/include/linux/instrumented.h
> > +++ b/include/linux/instrumented.h
> > @@ -167,9 +167,6 @@ instrument_copy_from_user_after(const void *to, con=
st
> > void __user *from,
> >   */
> >  #define instrument_get_user(to)                              \
> >  ({                                                   \
> > -     u64 __tmp =3D (u64)(to);                          \
> > -     kmsan_unpoison_memory(&__tmp, sizeof(__tmp));   \
> > -     to =3D __tmp;                                     \
> >  })
> >
> >
> > Once we know which one of these is the issue, we can figure out a prope=
r
> > fix.
> >
> > Thanks,
> >
> > -- Marco
> >
>
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--
Alexander Potapenko
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