sync/atomic: fix arm check64 bug

R=r, rsc
CC=golang-dev
https://golang.org/cl/4571059

diff --git a/src/pkg/sync/atomic/asm_arm.s b/src/pkg/sync/atomic/asm_arm.s
index 448a98a01007c662e650cd8f42557eef90a16b33..95e2f5be41d56bcc9974503cdff0485e194089c2 100644 (file)
--- a/src/pkg/sync/atomic/asm_arm.s
+++ b/src/pkg/sync/atomic/asm_arm.s
@@ -90,11 +90,11 @@ add64loop:
 TEXT   check64<>(SB),7,$16
        MOVW    $10, R1
        // 8-aligned stack address scratch space.
-       MOVW    $8(SP), R3
-       AND     $~7, R3
+       MOVW    $8(R13), R5
+       AND     $~7, R5
 loop:
-       LDREXD  (R3), R2
-       STREXD  R2, (R3), R0
+       LDREXD  (R5), R2
+       STREXD  R2, (R5), R0
        CMP     $0, R0
        BEQ     ok
        SUB     $1, R1