From: Fangrui Song <maskray@google.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Mark Rutland <mark.rutland@arm.com>,
Kees Cook <keescook@chromium.org>,
Tom Stellard <tstellar@redhat.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Nick Desaulniers <ndesaulniers@google.com>,
LKML <linux-kernel@vger.kernel.org>,
clang-built-linux <clang-built-linux@googlegroups.com>,
Sami Tolvanen <samitolvanen@google.com>,
Will Deacon <will@kernel.org>,
Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH] arm64: disable -fsanitize=shadow-call-stack for big-endian
Date: Wed, 27 May 2020 11:35:17 -0700 [thread overview]
Message-ID: <20200527183517.uhph2pvnkyf6c5p7@google.com> (raw)
In-Reply-To: <CAK8P3a3-L-AQomvTcBv-KH1cVVu6uYNT_-2Ofir3UgwzGjcSug@mail.gmail.com>
On 2020-05-27, Arnd Bergmann wrote:
>On Wed, May 27, 2020 at 7:28 PM 'Nick Desaulniers' via Clang Built
>Linux <clang-built-linux@googlegroups.com> wrote:
>>
>> On Wed, May 27, 2020 at 8:24 AM Mark Rutland <mark.rutland@arm.com> wrote:
>> >
>> > On Wed, May 27, 2020 at 03:39:46PM +0200, Arnd Bergmann wrote:
>> > > clang-11 and earlier do not support -fsanitize=shadow-call-stack
>> > > in combination with -mbig-endian, but the Kconfig check does not
>> > > pass the endianess flag, so building a big-endian kernel with
>> > > this fails at build time:
>> > >
>> > > clang: error: unsupported option '-fsanitize=shadow-call-stack' for target 'aarch64_be-unknown-linux'
>> > >
>> > > Change the Kconfig check to let Kconfig figure this out earlier
>> > > and prevent the broken configuration. I assume this is a bug
>> > > in clang that needs to be fixed, but we also have to work
>> > > around existing releases.
>> > >
>> > > Fixes: 5287569a790d ("arm64: Implement Shadow Call Stack")
>> > > Link: https://bugs.llvm.org/show_bug.cgi?id=46076
>> > > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
>> >
>> > I suspect this is similar to the patchable-function-entry issue, and
>> > this is an oversight that we'd rather fix toolchain side.
>> >
>> > Nick, Fangrui, thoughts?
>>
>> Exactly, Fangrui already has a fix: https://reviews.llvm.org/D80647.
>> Thanks Fangrui!
>
>Ok, great! I had opened the bug first so I could reference it in the
>commit changelog, it seems the fix came fast than I managed to
>send out the kernel workaround.
>
>Do we still want the kernel workaround anyway to make it work
>with older clang versions, or do we expect to fall back to not
>use the integrated assembler for the moment?
>
> Arnd
We can condition it on `CLANG_VERSION >= 100001` (assuming Tom (CCed)
is happy (and there is still time) cherrying pick the two commits https://bugs.llvm.org/show_bug.cgi?id=46076 to clang 10.0.1)
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next prev parent reply other threads:[~2020-05-27 18:35 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-27 13:39 [PATCH] arm64: disable -fsanitize=shadow-call-stack for big-endian Arnd Bergmann
2020-05-27 15:24 ` Mark Rutland
2020-05-27 17:28 ` Nick Desaulniers
2020-05-27 18:28 ` Arnd Bergmann
2020-05-27 18:35 ` Fangrui Song [this message]
2020-05-27 19:01 ` Arnd Bergmann
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