runtime: fix windows/amd64 exception handler

R=golang-dev, rsc
CC=golang-dev, hectorchu
https://golang.org/cl/5797077

diff --git a/src/pkg/runtime/sys_windows_amd64.s b/src/pkg/runtime/sys_windows_amd64.s
index c8402d70e6360956edb15b96fa4ae1d46a079a4d..041383ee89b8dbb3c4b9332d1d28031bd41e6e8d 100644 (file)
--- a/src/pkg/runtime/sys_windows_amd64.s
+++ b/src/pkg/runtime/sys_windows_amd64.s
@@ -137,7 +137,7 @@ TEXT runtime·sigtramp(SB),7,$0
        get_tls(CX)
 
        // check that m exists
-       MOVQ    m(BX), AX
+       MOVQ    m(CX), AX
        CMPQ    AX, $0
        JNE     2(PC)
        CALL    runtime·badsignal(SB)