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/linux/arm/signal.c b/src/pkg/runtime/linux/arm/signal.c
index 481bd13..843c40b 100644
--- a/src/pkg/runtime/linux/arm/signal.c
+++ b/src/pkg/runtime/linux/arm/signal.c
@@ -50,16 +50,15 @@
}
void
-runtime·sighandler(int32 sig, Siginfo *info, void *context)
+runtime·sighandler(int32 sig, Siginfo *info, void *context, G *gp)
{
Ucontext *uc;
Sigcontext *r;
- G *gp;
uc = context;
r = &uc->uc_mcontext;
- if((gp = m->curg) != nil && (runtime·sigtab[sig].flags & SigPanic)) {
+ if(gp != nil && (runtime·sigtab[sig].flags & SigPanic)) {
// Make it look like a call to the signal func.
// Have to pass arguments out of band since
// augmenting the stack frame would break
@@ -99,8 +98,8 @@
runtime·printf("\n");
if(runtime·gotraceback()){
- runtime·traceback((void*)r->arm_pc, (void*)r->arm_sp, (void*)r->arm_lr, m->curg);
- runtime·tracebackothers(m->curg);
+ runtime·traceback((void*)r->arm_pc, (void*)r->arm_sp, (void*)r->arm_lr, gp);
+ runtime·tracebackothers(gp);
runtime·printf("\n");
runtime·dumpregs(r);
}
diff --git a/src/pkg/runtime/linux/arm/sys.s b/src/pkg/runtime/linux/arm/sys.s
index b25cf81..6c222fc 100644
--- a/src/pkg/runtime/linux/arm/sys.s
+++ b/src/pkg/runtime/linux/arm/sys.s
@@ -197,11 +197,24 @@
RET
TEXT runtime·sigtramp(SB),7,$24
+ // save g
+ MOVW g, R3
+ MOVW g, 20(R13)
+
+ // g = m->gsignal
MOVW m_gsignal(m), g
+
+ // copy arguments for call to sighandler
MOVW R0, 4(R13)
MOVW R1, 8(R13)
MOVW R2, 12(R13)
+ MOVW R3, 16(R13)
+
BL runtime·sighandler(SB)
+
+ // restore g
+ MOVW 20(R13), g
+
RET
TEXT runtime·rt_sigaction(SB),7,$0
