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 b0e1864..3a96c2b 100644
--- a/src/runtime/sys_plan9_amd64.s
+++ b/src/runtime/sys_plan9_amd64.s
@@ -149,7 +149,7 @@
// 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.
