[PATCH] ARM: decompressor: a minor optimization
From: Dave.Martin@arm.com (Dave Martin)
Date: 2014-06-02 10:25:16
On Fri, May 30, 2014 at 08:30:33PM +0900, Masahiro Yamada wrote:
"ldr sp, [r0, #28]" can be squashed into the previous ldm instruction.
See commit 77754410fb8ecd7cf307bcd75d60f3b22b8c3cd2 ARM: 6286/1: fix Thumb-2 decompressor broken by "Auto calculate ZRELADDR" Loading sp with LDMIA is not allowed in Thumb. For simpler code maintenance, the code was just made Thumb-compatible anyway by splitting out the sp load while fixing another issue. This isn't part of a core loop, so shouldn't have a significant impact on performance. git blame can be useful for finding out how an odd-looking piece of code came into existence. Sometimes you have to dig through a few patches to find the answer. Cheers ---Dave
quoted hunk ↗ jump to hunk
Signed-off-by: Masahiro Yamada <redacted> --- arch/arm/boot/compressed/head.S | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S index 066b034..8c392c5 100644 --- a/arch/arm/boot/compressed/head.S +++ b/arch/arm/boot/compressed/head.S@@ -194,8 +194,7 @@ not_angel: blcs cache_on restart: adr r0, LC0 - ldmia r0, {r1, r2, r3, r6, r10, r11, r12} - ldr sp, [r0, #28] + ldmia r0, {r1, r2, r3, r6, r10, r11, r12, sp} /* * We might be running at a different address. We need-- 1.9.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel at lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel