From mboxrd@z Thu Jan 1 00:00:00 1970 From: catalin.marinas@arm.com (Catalin Marinas) Date: Wed, 20 Sep 2017 13:19:07 +0100 Subject: [PATCH] arm64: relax assembly code alignment from 16 byte to 4 byte In-Reply-To: References: <1504173383-8367-1-git-send-email-yamada.masahiro@socionext.com> <20170907164651.3bmhdkbnxvj3pz7g@armageddon.cambridge.arm.com> Message-ID: <20170920121907.x4jxd74tuogkb52a@localhost> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Wed, Sep 20, 2017 at 07:58:34PM +0900, Masahiro Yamada wrote: > 2017-09-08 1:46 GMT+09:00 Catalin Marinas : > > 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 > >> --- > >> > >> 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 > >> 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. -- Catalin