ARM: 6482/2: Fix find_next_zero_bit and related assembly

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.

Cc: <stable@kernel.org>
Reviewed-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Tested-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: James Jones <jajones@nvidia.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 4 insertions, 2 deletions

diff --git a/arch/arm/lib/findbit.S b/arch/arm/lib/findbit.S
index 1e4cbd4e7be..64f6bc1a913 100644
--- a/arch/arm/lib/findbit.S
+++ b/arch/arm/lib/findbit.S
@@ -174,8 +174,8 @@ ENDPROC(_find_next_bit_be)
  */
 .L_found:
 #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
 #endif
+                cmp     r1, r0                  @ Clamp to maxbit
+                movlo   r0, r1
                 mov     pc, lr