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-rw-r--r--arch/arm/include/asm/atomic.h26
-rw-r--r--arch/arm/kernel/entry-armv.S7
-rw-r--r--arch/arm/kernel/entry-header.S14
3 files changed, 21 insertions, 26 deletions
diff --git a/arch/arm/include/asm/atomic.h b/arch/arm/include/asm/atomic.h
index 9ed2377fe8e5..d0daeab2234e 100644
--- a/arch/arm/include/asm/atomic.h
+++ b/arch/arm/include/asm/atomic.h
@@ -19,31 +19,21 @@
#ifdef __KERNEL__
+/*
+ * On ARM, ordinary assignment (str instruction) doesn't clear the local
+ * strex/ldrex monitor on some implementations. The reason we can use it for
+ * atomic_set() is the clrex or dummy strex done on every exception return.
+ */
#define atomic_read(v) ((v)->counter)
+#define atomic_set(v,i) (((v)->counter) = (i))
#if __LINUX_ARM_ARCH__ >= 6
/*
* ARMv6 UP and SMP safe atomic ops. We use load exclusive and
* store exclusive to ensure that these are atomic. We may loop
- * to ensure that the update happens. Writing to 'v->counter'
- * without using the following operations WILL break the atomic
- * nature of these ops.
+ * to ensure that the update happens.
*/
-static inline void atomic_set(atomic_t *v, int i)
-{
- unsigned long tmp;
-
- __asm__ __volatile__("@ atomic_set\n"
-"1: ldrex %0, [%1]\n"
-" strex %0, %2, [%1]\n"
-" teq %0, #0\n"
-" bne 1b"
- : "=&r" (tmp)
- : "r" (&v->counter), "r" (i)
- : "cc");
-}
-
static inline void atomic_add(int i, atomic_t *v)
{
unsigned long tmp;
@@ -163,8 +153,6 @@ static inline void atomic_clear_mask(unsigned long mask, unsigned long *addr)
#error SMP not supported on pre-ARMv6 CPUs
#endif
-#define atomic_set(v,i) (((v)->counter) = (i))
-
static inline int atomic_add_return(int i, atomic_t *v)
{
unsigned long flags;
diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index 3d727a8a23bc..a332bc7225bf 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -734,13 +734,6 @@ ENTRY(__switch_to)
#ifdef CONFIG_MMU
ldr r6, [r2, #TI_CPU_DOMAIN]
#endif
-#if __LINUX_ARM_ARCH__ >= 6
-#ifdef CONFIG_CPU_32v6K
- clrex
-#else
- strex r5, r4, [ip] @ Clear exclusive monitor
-#endif
-#endif
#if defined(CONFIG_HAS_TLS_REG)
mcr p15, 0, r3, c13, c0, 3 @ set TLS register
#elif !defined(CONFIG_TLS_REG_EMUL)
diff --git a/arch/arm/kernel/entry-header.S b/arch/arm/kernel/entry-header.S
index a4eaf4f920c5..e17e3c30d957 100644
--- a/arch/arm/kernel/entry-header.S
+++ b/arch/arm/kernel/entry-header.S
@@ -76,13 +76,25 @@
#ifndef CONFIG_THUMB2_KERNEL
.macro svc_exit, rpsr
msr spsr_cxsf, \rpsr
+#if defined(CONFIG_CPU_32v6K)
+ clrex @ clear the exclusive monitor
ldmia sp, {r0 - pc}^ @ load r0 - pc, cpsr
+#elif defined (CONFIG_CPU_V6)
+ ldr r0, [sp]
+ strex r1, r2, [sp] @ clear the exclusive monitor
+ ldmib sp, {r1 - pc}^ @ load r1 - pc, cpsr
+#endif
.endm
.macro restore_user_regs, fast = 0, offset = 0
ldr r1, [sp, #\offset + S_PSR] @ get calling cpsr
ldr lr, [sp, #\offset + S_PC]! @ get pc
msr spsr_cxsf, r1 @ save in spsr_svc
+#if defined(CONFIG_CPU_32v6K)
+ clrex @ clear the exclusive monitor
+#elif defined (CONFIG_CPU_V6)
+ strex r1, r2, [sp] @ clear the exclusive monitor
+#endif
.if \fast
ldmdb sp, {r1 - lr}^ @ get calling r1 - lr
.else
@@ -98,6 +110,7 @@
.endm
#else /* CONFIG_THUMB2_KERNEL */
.macro svc_exit, rpsr
+ clrex @ clear the exclusive monitor
ldr r0, [sp, #S_SP] @ top of the stack
ldr r1, [sp, #S_PC] @ return address
tst r0, #4 @ orig stack 8-byte aligned?
@@ -110,6 +123,7 @@
.endm
.macro restore_user_regs, fast = 0, offset = 0
+ clrex @ clear the exclusive monitor
mov r2, sp
load_user_sp_lr r2, r3, \offset + S_SP @ calling sp, lr
ldr r1, [sp, #\offset + S_PSR] @ get calling cpsr
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