runtime: pass to signal handler value of g at time of signal
The existing code assumed that signals only arrived
while executing on the goroutine stack (g == m->curg),
not while executing on the scheduler stack (g == m->g0).
Most of the signal handling trampolines correctly saved
and restored g already, but the sighandler C code did not
have access to it.
Some rewriting of assembly to make the various
implementations as similar as possible.
Will need to change Windows too but I don't
understand how sigtramp gets called there.
R=r
CC=golang-dev
https://golang.org/cl/4203042
diff --git a/src/pkg/runtime/darwin/386/sys.s b/src/pkg/runtime/darwin/386/sys.s
index 7961e36..9d2caca 100644
--- a/src/pkg/runtime/darwin/386/sys.s
+++ b/src/pkg/runtime/darwin/386/sys.s
@@ -80,33 +80,34 @@
get_tls(CX)
// save g
- MOVL g(CX), BP
- MOVL BP, 20(SP)
+ MOVL g(CX), DI
+ MOVL DI, 20(SP)
// g = m->gsignal
MOVL m(CX), BP
MOVL m_gsignal(BP), BP
MOVL BP, g(CX)
- MOVL handler+0(FP), DI
- // 4(FP) is sigstyle
- MOVL signo+8(FP), AX
- MOVL siginfo+12(FP), BX
- MOVL context+16(FP), CX
-
- MOVL AX, 0(SP)
+ // copy arguments to sighandler
+ MOVL sig+8(FP), BX
+ MOVL BX, 0(SP)
+ MOVL info+12(FP), BX
MOVL BX, 4(SP)
- MOVL CX, 8(SP)
- CALL DI
+ MOVL context+16(FP), BX
+ MOVL BX, 8(SP)
+ MOVL DI, 12(SP)
+
+ MOVL handler+0(FP), BX
+ CALL BX
// restore g
get_tls(CX)
- MOVL 20(SP), BP
- MOVL BP, g(CX)
+ MOVL 20(SP), DI
+ MOVL DI, g(CX)
+ // call sigreturn
MOVL context+16(FP), CX
MOVL style+4(FP), BX
-
MOVL $0, 0(SP) // "caller PC" - ignored
MOVL CX, 4(SP)
MOVL BX, 8(SP)
