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runtime: save LR to stack when panicking to handle leaf function traceback

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R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/7289047
This commit is contained in:
Shenghou Ma 2013-02-06 01:18:37 +08:00
parent 4360ef8de2
commit 7de3d71797
2 changed files with 17 additions and 5 deletions
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16
src/pkg/runtime/signal_linux_arm.c
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@ -68,11 +68,17 @@ runtime·sighandler(int32 sig, Siginfo *info, void *context, G *gp)
gp->sigcode1 = r->fault_address;
gp->sigpc = r->arm_pc;
// If this is a leaf function, we do smash LR,
// but we're not going back there anyway.
// Don't bother smashing if r->arm_pc is 0,
// which is probably a call to a nil func: the
// old link register is more useful in the stack trace.
// We arrange lr, and pc to pretend the panicking
// function calls sigpanic directly.
// Always save LR to stack so that panics in leaf
// functions are correctly handled. This smashes
// the stack frame but we're not going back there
// anyway.
r->arm_sp -= 4;
*(uint32 *)r->arm_sp = r->arm_lr;
// Don't bother saving PC if it's zero, which is
// probably a call to a nil func: the old link register
// is more useful in the stack trace.
if(r->arm_pc != 0)
r->arm_lr = r->arm_pc;
// In case we are panicking from external C code

6
src/pkg/runtime/traceback_arm.c
View File

@ -182,6 +182,12 @@ runtime·gentraceback(byte *pc0, byte *sp, byte *lr0, G *gp, int32 skip, uintptr
// If this was deferproc or newproc, the caller had an extra 12.
if(f->entry == (uintptr)runtime·deferproc || f->entry == (uintptr)runtime·newproc)
sp += 12;
// sighandler saves the lr on stack before fake a call to sigpanic
if(waspanic) {
pc = *(uintptr *)sp;
sp += 4;
}
}
if(pcbuf == nil && (pc = gp->gopc) != 0 && (f = runtime·findfunc(pc)) != nil