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ARM: fix the memset fix 

From Kernel commit 418df63a ARM: 7670/1: fix the memset fix

| Commit 455bd4c430b0 ("ARM: 7668/1: fix memset-related crashes caused by
| recent GCC (4.7.2) optimizations") attempted to fix a compliance issue
| with the memset return value.  However the memset itself became broken
| by that patch for misaligned pointers.
|
| This fixes the above by branching over the entry code from the
| misaligned fixup code to avoid reloading the original pointer.
|
| Also, because the function entry alignment is wrong in the Thumb mode
| compilation, that fixup code is moved to the end.
|
| While at it, the entry instructions are slightly reworked to help dual
| issue pipelines.
|
| Signed-off-by: Nicolas Pitre <nico@linaro.org>
| Tested-by: Alexander Holler <holler@ahsoftware.de>
| Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
This commit is contained in:
Nicolas Pitre 2013-03-12 13:00:42 +01:00 committed by Sascha Hauer
parent 2683e56174
commit 4586f9626b
1 changed files with 13 additions and 20 deletions
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33
arch/arm/lib/memset.S
View File

@ -14,31 +14,15 @@
.text
.align 5
.word 0
1: subs r2, r2, #4 @ 1 do we have enough
blt 5f @ 1 bytes to align with?
cmp r3, #2 @ 1
strltb r1, [ip], #1 @ 1
strleb r1, [ip], #1 @ 1
strb r1, [ip], #1 @ 1
add r2, r2, r3 @ 1 (r2 = r2 - (4 - r3))
/*
* The pointer is now aligned and the length is adjusted. Try doing the
* memset again.
*/
ENTRY(memset)
/*
* Preserve the contents of r0 for the return value.
*/
mov ip, r0
ands r3, ip, #3 @ 1 unaligned?
bne 1b @ 1
ands r3, r0, #3 @ 1 unaligned?
mov ip, r0 @ preserve r0 as return value
bne 6f @ 1
/*
* we know that the pointer in ip is aligned to a word boundary.
*/
orr r1, r1, r1, lsl #8
1: orr r1, r1, r1, lsl #8
orr r1, r1, r1, lsl #16
mov r3, r1
cmp r2, #16
@ -127,5 +111,14 @@ ENTRY(memset)
tst r2, #1
strneb r1, [ip], #1
mov pc, lr
6: subs r2, r2, #4 @ 1 do we have enough
blt 5b @ 1 bytes to align with?
cmp r3, #2 @ 1
strltb r1, [ip], #1 @ 1
strleb r1, [ip], #1 @ 1
strb r1, [ip], #1 @ 1
add r2, r2, r3 @ 1 (r2 = r2 - (4 - r3))
b 1b
ENDPROC(memset)