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From:   Dmitry Vyukov <dvyukov@google.com>
Date:   Fri, 9 Sep 2022 10:38:44 +0200
Message-ID: <CACT4Y+ZJXS0Hcj4D-O+KfXT0SJ9pUhEx=zDqhwgOa9Pz2te0KQ@mail.gmail.com>
Subject: Re: [PATCH v2 3/3] objtool, kcsan: Add volatile read/write
 instrumentation to whitelist
To:     Marco Elver <elver@google.com>
Cc:     "Paul E. McKenney" <paulmck@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Potapenko <glider@google.com>,
        Boqun Feng <boqun.feng@gmail.com>, kasan-dev@googlegroups.com,
        linux-kernel@vger.kernel.org,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        llvm@lists.linux.dev, Heiko Carstens <hca@linux.ibm.com>,
        Vasily Gorbik <gor@linux.ibm.com>,
        Alexander Gordeev <agordeev@linux.ibm.com>,
        Christian Borntraeger <borntraeger@linux.ibm.com>,
        Sven Schnelle <svens@linux.ibm.com>,
        Peter Zijlstra <peterz@infradead.org>,
        linux-s390@vger.kernel.org
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On Fri, 9 Sept 2022 at 09:38, Marco Elver <elver@google.com> wrote:
>
> Adds KCSAN's volatile instrumentation to objtool's uaccess whitelist.
>
> Recent kernel change have shown that this was missing from the uaccess
> whitelist (since the first upstreamed version of KCSAN):
>
>   mm/gup.o: warning: objtool: fault_in_readable+0x101: call to __tsan_volatile_write1() with UACCESS enabled
>
> Fixes: 75d75b7a4d54 ("kcsan: Support distinguishing volatile accesses")
> Signed-off-by: Marco Elver <elver@google.com>

Reviewed-by: Dmitry Vyukov <dvyukov@google.com>

> ---
> v2:
> * Fix commit message.
> ---
>  tools/objtool/check.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
>
> diff --git a/tools/objtool/check.c b/tools/objtool/check.c
> index e55fdf952a3a..67afdce3421f 100644
> --- a/tools/objtool/check.c
> +++ b/tools/objtool/check.c
> @@ -999,6 +999,16 @@ static const char *uaccess_safe_builtin[] = {
>         "__tsan_read_write4",
>         "__tsan_read_write8",
>         "__tsan_read_write16",
> +       "__tsan_volatile_read1",
> +       "__tsan_volatile_read2",
> +       "__tsan_volatile_read4",
> +       "__tsan_volatile_read8",
> +       "__tsan_volatile_read16",
> +       "__tsan_volatile_write1",
> +       "__tsan_volatile_write2",
> +       "__tsan_volatile_write4",
> +       "__tsan_volatile_write8",
> +       "__tsan_volatile_write16",
>         "__tsan_atomic8_load",
>         "__tsan_atomic16_load",
>         "__tsan_atomic32_load",
> --
> 2.37.2.789.g6183377224-goog
>