runtime: make onM and mcall take Go func values
This gives them correct types in Go and also makes it
possible to use them to run Go code on an m stack.
LGTM=iant
R=golang-codereviews, dave, iant
CC=dvyukov, golang-codereviews, khr, r
https://golang.org/cl/137970044
diff --git a/src/pkg/runtime/asm_amd64.s b/src/pkg/runtime/asm_amd64.s
index 0933fa9..1d98fc2 100644
--- a/src/pkg/runtime/asm_amd64.s
+++ b/src/pkg/runtime/asm_amd64.s
@@ -153,7 +153,7 @@
MOVQ gobuf_pc(BX), BX
JMP BX
-// void mcall(void (*fn)(G*))
+// func mcall(fn func(*g))
// Switch to m->g0's stack, call fn(g).
// Fn must never return. It should gogo(&g->sched)
// to keep running g.
@@ -180,6 +180,8 @@
MOVQ (g_sched+gobuf_sp)(SI), SP // sp = m->g0->sched.sp
PUSHQ AX
ARGSIZE(8)
+ MOVQ DI, DX
+ MOVQ 0(DI), DI
CALL DI
POPQ AX
MOVQ $runtime·badmcall2(SB), AX
@@ -194,7 +196,7 @@
TEXT runtime·switchtoM(SB), NOSPLIT, $0-8
RET
-// void onM(void (*fn)())
+// func onM(fn func())
// calls fn() on the M stack.
// switches to the M stack if not already on it, and
// switches back when fn() returns.
@@ -220,6 +222,8 @@
// call target function
ARGSIZE(0)
+ MOVQ DI, DX
+ MOVQ 0(DI), DI
CALL DI
// switch back to g
@@ -234,6 +238,8 @@
onm:
// already on m stack, just call directly
+ MOVQ DI, DX
+ MOVQ 0(DI), DI
CALL DI
RET
