[PATCH] ARM: bitops: Fix low-level code to be Thumb-2 compatible
Dave Martin
dave.martin at linaro.org
Wed Feb 2 13:53:44 EST 2011
The new bitops code cunningly str <Rt>, [r1, -r1] to trigger
a fault by attempting to store to address zero.
This code doesn't assemble in Thumb-2, since Thumb-2 doesn't
allow negative register offsets at all for loads and stores.
The patch loads 0 into r2 and uses that as a base register
instead for the Thumb-2 case: r2 seems non-live at every
instance of this problem.
The ARM case is unaffected.
Signed-off-by: Dave Martin <dave.martin at linaro.org>
---
arch/arm/lib/bitops.h | 16 ++++++++++++----
1 files changed, 12 insertions(+), 4 deletions(-)
diff --git a/arch/arm/lib/bitops.h b/arch/arm/lib/bitops.h
index f8a2bd3..87d6b17 100644
--- a/arch/arm/lib/bitops.h
+++ b/arch/arm/lib/bitops.h
@@ -1,7 +1,9 @@
#if __LINUX_ARM_ARCH__ >= 6
.macro bitop, instr
tst r1, #3
- strne r1, [r1, -r1] @ assert word-aligned
+ ARM( strne r1, [r1, -r1] ) @ assert word-aligned
+ THUMB( movne r2, #0 )
+ THUMB( strne r1, [r2] )
mov r2, #1
and r3, r0, #31 @ Get bit offset
mov r0, r0, lsr #5
@@ -17,7 +19,9 @@
.macro testop, instr, store
tst r1, #3
- strne r1, [r1, -r1] @ assert word-aligned
+ ARM( strne r1, [r1, -r1] ) @ assert word-aligned
+ THUMB( movne r2, #0 )
+ THUMB( strne r1, [r2] )
mov r2, #1
and r3, r0, #31 @ Get bit offset
mov r0, r0, lsr #5
@@ -38,7 +42,9 @@
#else
.macro bitop, instr
tst r1, #3
- strne r1, [r1, -r1] @ assert word-aligned
+ ARM( strne r1, [r1, -r1] ) @ assert word-aligned
+ THUMB( movne r2, #0 )
+ THUMB( strne r1, [r2] )
and r2, r0, #31
mov r0, r0, lsr #5
mov r3, #1
@@ -61,7 +67,9 @@
*/
.macro testop, instr, store
tst r1, #3
- strne r1, [r1, -r1] @ assert word-aligned
+ ARM( strne r1, [r1, -r1] ) @ assert word-aligned
+ THUMB( movne r2, #0 )
+ THUMB( strne r1, [r2] )
and r3, r0, #31
mov r0, r0, lsr #5
save_and_disable_irqs ip
--
1.7.1
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