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ARM: 8223/1: Add unwinding support for __memzero function

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The __memzero function never had unwinding annotations added.
Currently, when accessing invalid pointer by __memzero occurs the
backtrace shown will stop at __memzero or some completely unrelated
function. Add unwinding annotations in hopes of getting a more
useful backtrace in following cases:
1. die on accessing invalid pointer by __memzero
2. kprobe trapped at any instruction within __memzero
3. interrupted at any instruction within __memzero

Signed-off-by: Lin Yongting <linyongting@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Lin Yongting 2014-11-26 14:33:49 +01:00 committed by Russell King
parent 296630c9c8
commit 20cb6abfe0
1 changed files with 12 additions and 0 deletions
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12
arch/arm/lib/memzero.S
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@ -9,6 +9,7 @@
*/
#include <linux/linkage.h>
#include <asm/assembler.h>
#include <asm/unwind.h>
.text
.align 5
@ -18,6 +19,7 @@
* mis-aligned by, and r1 is the number of bytes. If r1 < 4, then we
* don't bother; we use byte stores instead.
*/
UNWIND( .fnstart )
1: subs r1, r1, #4 @ 1 do we have enough
blt 5f @ 1 bytes to align with?
cmp r3, #2 @ 1
@ -47,6 +49,9 @@ ENTRY(__memzero)
* use the LR
*/
str lr, [sp, #-4]! @ 1
UNWIND( .fnend )
UNWIND( .fnstart )
UNWIND( .save {lr} )
mov ip, r2 @ 1
mov lr, r2 @ 1
@ -66,6 +71,7 @@ ENTRY(__memzero)
tst r1, #16 @ 1 16 bytes or more?
stmneia r0!, {r2, r3, ip, lr} @ 4
ldr lr, [sp], #4 @ 1
UNWIND( .fnend )
#else
@ -75,6 +81,9 @@ ENTRY(__memzero)
*/
stmfd sp!, {r4-r7, lr}
UNWIND( .fnend )
UNWIND( .fnstart )
UNWIND( .save {r4-r7, lr} )
mov r4, r2
mov r5, r2
mov r6, r2
@ -105,9 +114,11 @@ ENTRY(__memzero)
tst r1, #16
stmneia r0!, {r4-r7}
ldmfd sp!, {r4-r7, lr}
UNWIND( .fnend )
#endif
UNWIND( .fnstart )
4: tst r1, #8 @ 1 8 bytes or more?
stmneia r0!, {r2, r3} @ 2
tst r1, #4 @ 1 4 bytes or more?
@ -122,4 +133,5 @@ ENTRY(__memzero)
tst r1, #1 @ 1 a byte left over
strneb r2, [r0], #1 @ 1
ret lr @ 1
UNWIND( .fnend )
ENDPROC(__memzero)