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Subject[PATCH] arm64: relax assembly code alignment from 16 byte to 4 byte
Date
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.


arch/arm64/include/asm/linkage.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/linkage.h b/arch/arm64/include/asm/linkage.h
index 636c1bc..1b26629 100644
--- a/arch/arm64/include/asm/linkage.h
+++ b/arch/arm64/include/asm/linkage.h
@@ -1,7 +1,7 @@
#ifndef __ASM_LINKAGE_H
#define __ASM_LINKAGE_H

-#define __ALIGN .align 4
-#define __ALIGN_STR ".align 4"
+#define __ALIGN .align 2
+#define __ALIGN_STR ".align 2"

#endif
--
2.7.4
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