1 files changed, 15 insertions, 14 deletions

diff --git a/arch/arm/kernel/entry-header.S b/arch/arm/kernel/entry-header.S
index 8db307d0954b..2fdf8679b46e 100644
--- a/arch/arm/kernel/entry-header.S
+++ b/arch/arm/kernel/entry-header.S
@@ -208,26 +208,21 @@
 #endif
         .endif
         msr     spsr_cxsf, \rpsr
-#if defined(CONFIG_CPU_V6)
-        ldr     r0, [sp]
-        strex   r1, r2, [sp]                    @ clear the exclusive monitor
-        ldmib   sp, {r1 - pc}^                  @ load r1 - pc, cpsr
-#elif defined(CONFIG_CPU_32v6K)
-        clrex                                   @ clear the exclusive monitor
-        ldmia   sp, {r0 - pc}^                  @ load r0 - pc, cpsr
-#else
-        ldmia   sp, {r0 - pc}^                  @ load r0 - pc, cpsr
+#if defined(CONFIG_CPU_V6) || defined(CONFIG_CPU_32v6K)
+        @ We must avoid clrex due to Cortex-A15 erratum #830321
+        sub     r0, sp, #4                      @ uninhabited address
+        strex   r1, r2, [r0]                    @ clear the exclusive monitor
 #endif
+        ldmia   sp, {r0 - pc}^                  @ load r0 - pc, cpsr
         .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_V6)
+#if defined(CONFIG_CPU_V6) || defined(CONFIG_CPU_32v6K)
+        @ We must avoid clrex due to Cortex-A15 erratum #830321
         strex   r1, r2, [sp]                    @ clear the exclusive monitor
-#elif defined(CONFIG_CPU_32v6K)
-        clrex                                   @ clear the exclusive monitor
 #endif
         .if     \fast
         ldmdb   sp, {r1 - lr}^                  @ get calling r1 - lr
@@ -261,7 +256,10 @@
         .endif
         ldr     lr, [sp, #S_SP]                 @ top of the stack
         ldrd    r0, r1, [sp, #S_LR]             @ calling lr and pc
-        clrex                                   @ clear the exclusive monitor
+
+        @ We must avoid clrex due to Cortex-A15 erratum #830321
+        strex   r2, r1, [sp, #S_LR]             @ clear the exclusive monitor
+
         stmdb   lr!, {r0, r1, \rpsr}            @ calling lr and rfe context
         ldmia   sp, {r0 - r12}
         mov     sp, lr
@@ -282,13 +280,16 @@
         .endm
 #else   /* ifdef CONFIG_CPU_V7M */
         .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
         ldr     lr, [sp, #\offset + S_PC]       @ get pc
         add     sp, sp, #\offset + S_SP
         msr     spsr_cxsf, r1                   @ save in spsr_svc
+
+        @ We must avoid clrex due to Cortex-A15 erratum #830321
+        strex   r1, r2, [sp]                    @ clear the exclusive monitor
+
         .if     \fast
         ldmdb   sp, {r1 - r12}                  @ get calling r1 - r12
         .else