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Date:   Wed, 6 May 2020 10:34:16 -0700
From:   Fangrui Song <maskray@google.com>
To:     Nick Desaulniers <ndesaulniers@google.com>
Cc:     Nathan Chancellor <natechancellor@gmail.com>,
        Ard Biesheuvel <ardb@kernel.org>,
        Arnd Bergmann <arnd@arndb.de>, Torsten Duwe <duwe@lst.de>,
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        Will Deacon <will@kernel.org>,
        Amit Daniel Kachhap <amit.kachhap@arm.com>,
        Torsten Duwe <duwe@suse.de>,
        Ard Biesheuvel <ard.biesheuvel@linaro.org>,
        AKASHI Takahiro <takahiro.akashi@linaro.org>,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        Julien Thierry <jthierry@redhat.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Marc Zyngier <maz@kernel.org>,
        Kees Cook <keescook@chromium.org>,
        Alexandre Ghiti <alex@ghiti.fr>,
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Subject: Re: [PATCH] arm64: disable patchable function entry on big-endian
 clang builds
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On 2020-05-06, Nick Desaulniers wrote:
>On Wed, May 6, 2020 at 8:46 AM 'Fangrui Song' via Clang Built Linux
><clang-built-linux@googlegroups.com> wrote:
>> Created https://reviews.llvm.org/D79495 to allow the function attribute
>> 'patchable_function_entry' on aarch64_be.
>> I think -fpatchable-function-entry= just works.
>>
>> Note, LLD does not support aarch64_be
>> (https://github.com/ClangBuiltLinux/linux/issues/380).
>
>I've approved the patch. Thanks for the quick fix.  Looks like we
>backported -fpatchable-function-entry= to the clang-10 release, so we
>should cherry pick your fix to the release-10 branch for the clang
>10.1 release.
>
>I'd rather have this fixed on the toolchain side.

+1.

Cherry picked to release/10.x
https://github.com/llvm/llvm-project/commit/98f9f73f6d2367aa8001c4d16de9d3b347febb08
I did not use any endianness-sensitive in the original implementation,
so hopefully this will not run into issues.


The scheduled rc1 of LLVM 10.0.1 will happen on May 18, 2020
(https://lists.llvm.org/pipermail/llvm-dev/2020-April/141128.html)
We should be quick if we want to test it on qemu or real hardware.