[34-longterm 097/209] ARM: 6482/2: Fix find_next_zero_bit and related assembly

From: Paul Gortmaker
Date: Thu Apr 14 2011 - 13:51:08 EST

From: James Jones <jajones@xxxxxxxxxx>

| This is a commit scheduled for the next v2.6.34 longterm release. |
| If you see a problem with using this for longterm, please comment.|

commit 0e91ec0c06d2cd15071a6021c94840a50e6671aa upstream.

The find_next_bit, find_first_bit, find_next_zero_bit
and find_first_zero_bit functions were not properly
clamping to the maxbit argument at the bit level. They
were instead only checking maxbit at the byte level.
To fix this, add a compare and a conditional move
instruction to the end of the common bit-within-the-
byte code used by all the functions and be sure not to
clobber the maxbit argument before it is used.

Reviewed-by: Nicolas Pitre <nicolas.pitre@xxxxxxxxxx>
Tested-by: Stephen Warren <swarren@xxxxxxxxxx>
Signed-off-by: James Jones <jajones@xxxxxxxxxx>
Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx>
Signed-off-by: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
arch/arm/lib/findbit.S | 6 ++++--
1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/arm/lib/findbit.S b/arch/arm/lib/findbit.S
index 1e4cbd4..64f6bc1 100644
--- a/arch/arm/lib/findbit.S
+++ b/arch/arm/lib/findbit.S
@@ -174,8 +174,8 @@ ENDPROC(_find_next_bit_be)
#if __LINUX_ARM_ARCH__ >= 5
- rsb r1, r3, #0
- and r3, r3, r1
+ rsb r0, r3, #0
+ and r3, r3, r0
clz r3, r3
rsb r3, r3, #31
add r0, r2, r3
@@ -190,5 +190,7 @@ ENDPROC(_find_next_bit_be)
addeq r2, r2, #1
mov r0, r2
+ cmp r1, r0 @ Clamp to maxbit
+ movlo r0, r1
mov pc, lr


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