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SubjectRe: [PATCH] arm64: relax assembly code alignment from 16 byte to 4 byte
On Thu, Aug 31, 2017 at 06:56:23PM +0900, Masahiro Yamada wrote:
> Aarch64 instructions must be word aligned. The current 16 byte
> alignment is more than enough. Relax it into 4 byte alignment.
>
> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
> ---
>
> I do not know why arm64 Linux requires 16 byte alignment.
>
> I dug git-history of arch/arm64/include/asm/linkage.h
> and the only commit I see is:
>
> commit aeed41a9371ee02257b608eb06a9058507a7d0f4
> Author: Marc Zyngier <Marc.Zyngier@arm.com>
> Date: Fri Oct 19 17:33:27 2012 +0100
>
> arm64: fix alignment padding in assembly code
>
> It just opt out of the asm-generic variant to remove 0x90.
> So, the amount of alignment might not be not optimized yet.
>
> Please correct me if I am missing something.

Not sure why we ended up with 4. Possibly because we forgot the power of
2 difference for arm/arm64.

Queued for 4.14. Thanks.

--
Catalin

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