runtime: save correct pid for new m's on plan9/amd64

The pid field in the Tos structure is a 32-bit value.
Loading a 64-bit word also brings in the next field
which is used for the profiling clock.

LGTM=0intro, aram
R=rsc, 0intro, aram
CC=golang-codereviews, mischief
https://golang.org/cl/139560044

diff --git a/src/runtime/sys_plan9_amd64.s b/src/runtime/sys_plan9_amd64.s
index b0e1864602b48237f004d941f0485d3287d3a43a..3a96c2bf915b73be9da49b9cd84e8053f0dbbfa3 100644 (file)
--- a/src/runtime/sys_plan9_amd64.s
+++ b/src/runtime/sys_plan9_amd64.s
@@ -149,7 +149,7 @@ TEXT runtime·tstart_plan9(SB),NOSPLIT,$0
 
        // Initialize procid from TOS struct.
        MOVQ    _tos(SB), AX
-       MOVQ    64(AX), AX
+       MOVL    64(AX), AX
        MOVQ    AX, m_procid(CX)        // save pid as m->procid
 
        // Finally, initialize g.