Re: [PATCH] arm64: relax assembly code alignment from 16 byte to 4 byte
From: Catalin Marinas
Date: Wed Sep 20 2017 - 08:19:17 EST
On Wed, Sep 20, 2017 at 07:58:34PM +0900, Masahiro Yamada wrote:
> 2017-09-08 1:46 GMT+09:00 Catalin Marinas <catalin.marinas@xxxxxxx>:
> > 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@xxxxxxxxxxxxx>
> >> ---
> >> 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@xxxxxxx>
> >> 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.
> I still do not see this patch in linux-next.
It won't make it into linux-next now, I'll push it as a fix for -rc2
(sorry, I've been away at Plumbers and didn't get the chance to send any
pull request). I'll push the patch out on fixes/core once I investigate
some unrelated failures.