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Commit 159a90b9 authored by Ian Lance Taylor's avatar Ian Lance Taylor
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runtime: merge Unix sighandler functions 

Replace all the Unix sighandler functions with a single instance.
Push the relatively small amount of processor-specific code into five
methods on sigctxt: sigpc, sigsp, siglr, fault, preparePanic.
(Some processors already had a fault method.)

Change-Id: Ib459412ff8f7e0f5ad06bfd43eb827c8b196fc32
Reviewed-on: https://go-review.googlesource.com/29752
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: 's avatarDavid Crawshaw <crawshaw@golang.org>
parent 890c09ef
Hide whitespace changes
Inline Side-by-side
Showing with 398 additions and 952 deletions
src/runtime/signal_386.go
View file @ 159a90b9
......@@ -27,152 +27,54 @@ func dumpregs(c *sigctxt) {
print("gs ", hex(c.gs()), "\n")
}
var crashing int32
// May run during STW, so write barriers are not allowed.
//
//go:nowritebarrierrec
func sighandler(sig uint32, info *siginfo, ctxt unsafe.Pointer, gp *g) {
_g_ := getg()
c := &sigctxt{info, ctxt}
if sig == _SIGPROF {
sigprof(uintptr(c.eip()), uintptr(c.esp()), 0, gp, _g_.m)
return
}
flags := int32(_SigThrow)
if sig < uint32(len(sigtable)) {
flags = sigtable[sig].flags
}
if c.sigcode() != _SI_USER && flags&_SigPanic != 0 {
// Make it look like a call to the signal func.
// Have to pass arguments out of band since
// augmenting the stack frame would break
// the unwinding code.
gp.sig = sig
gp.sigcode0 = uintptr(c.sigcode())
gp.sigcode1 = uintptr(c.sigaddr())
gp.sigpc = uintptr(c.eip())
if GOOS == "darwin" {
// Work around Leopard bug that doesn't set FPE_INTDIV.
// Look at instruction to see if it is a divide.
// Not necessary in Snow Leopard (si_code will be != 0).
if sig == _SIGFPE && gp.sigcode0 == 0 {
pc := (*[4]byte)(unsafe.Pointer(gp.sigpc))
i := 0
if pc[i] == 0x66 { // 16-bit instruction prefix
i++
}
if pc[i] == 0xF6 || pc[i] == 0xF7 {
gp.sigcode0 = _FPE_INTDIV
}
func (c *sigctxt) sigpc() uintptr { return uintptr(c.eip()) }
func (c *sigctxt) sigsp() uintptr { return uintptr(c.esp()) }
func (c *sigctxt) siglr() uintptr { return 0 }
func (c *sigctxt) fault() uintptr { return uintptr(c.sigaddr()) }
// preparePanic sets up the stack to look like a call to sigpanic.
func (c *sigctxt) preparePanic(sig uint32, gp *g) {
if GOOS == "darwin" {
// Work around Leopard bug that doesn't set FPE_INTDIV.
// Look at instruction to see if it is a divide.
// Not necessary in Snow Leopard (si_code will be != 0).
if sig == _SIGFPE && gp.sigcode0 == 0 {
pc := (*[4]byte)(unsafe.Pointer(gp.sigpc))
i := 0
if pc[i] == 0x66 { // 16-bit instruction prefix
i++
}
}
pc := uintptr(c.eip())
sp := uintptr(c.esp())
// If we don't recognize the PC as code
// but we do recognize the top pointer on the stack as code,
// then assume this was a call to non-code and treat like
// pc == 0, to make unwinding show the context.
if pc != 0 && findfunc(pc) == nil && findfunc(*(*uintptr)(unsafe.Pointer(sp))) != nil {
pc = 0
}
// Only push runtime.sigpanic if pc != 0.
// If pc == 0, probably panicked because of a
// call to a nil func. Not pushing that onto sp will
// make the trace look like a call to runtime.sigpanic instead.
// (Otherwise the trace will end at runtime.sigpanic and we
// won't get to see who faulted.)
if pc != 0 {
if sys.RegSize > sys.PtrSize {
sp -= sys.PtrSize
*(*uintptr)(unsafe.Pointer(sp)) = 0
if pc[i] == 0xF6 || pc[i] == 0xF7 {
gp.sigcode0 = _FPE_INTDIV
}
sp -= sys.PtrSize
*(*uintptr)(unsafe.Pointer(sp)) = pc
c.set_esp(uint32(sp))
}
c.set_eip(uint32(funcPC(sigpanic)))
return
}
if c.sigcode() == _SI_USER || flags&_SigNotify != 0 {
if sigsend(sig) {
return
}
}
if c.sigcode() == _SI_USER && signal_ignored(sig) {
return
}
if flags&_SigKill != 0 {
dieFromSignal(int32(sig))
}
if flags&_SigThrow == 0 {
return
}
_g_.m.throwing = 1
_g_.m.caughtsig.set(gp)
if crashing == 0 {
startpanic()
}
pc := uintptr(c.eip())
sp := uintptr(c.esp())
if sig < uint32(len(sigtable)) {
print(sigtable[sig].name, "\n")
} else {
print("Signal ", sig, "\n")
// If we don't recognize the PC as code
// but we do recognize the top pointer on the stack as code,
// then assume this was a call to non-code and treat like
// pc == 0, to make unwinding show the context.
if pc != 0 && findfunc(pc) == nil && findfunc(*(*uintptr)(unsafe.Pointer(sp))) != nil {
pc = 0
}
print("PC=", hex(c.eip()), " m=", _g_.m.id, "\n")
if _g_.m.lockedg != nil && _g_.m.ncgo > 0 && gp == _g_.m.g0 {
print("signal arrived during cgo execution\n")
gp = _g_.m.lockedg
}
print("\n")
level, _, docrash := gotraceback()
if level > 0 {
goroutineheader(gp)
tracebacktrap(uintptr(c.eip()), uintptr(c.esp()), 0, gp)
if crashing > 0 && gp != _g_.m.curg && _g_.m.curg != nil && readgstatus(_g_.m.curg)&^_Gscan == _Grunning {
// tracebackothers on original m skipped this one; trace it now.
goroutineheader(_g_.m.curg)
traceback(^uintptr(0), ^uintptr(0), 0, gp)
} else if crashing == 0 {
tracebackothers(gp)
print("\n")
}
dumpregs(c)
}
if docrash {
crashing++
if crashing < sched.mcount {
// There are other m's that need to dump their stacks.
// Relay SIGQUIT to the next m by sending it to the current process.
// All m's that have already received SIGQUIT have signal masks blocking
// receipt of any signals, so the SIGQUIT will go to an m that hasn't seen it yet.
// When the last m receives the SIGQUIT, it will fall through to the call to
// crash below. Just in case the relaying gets botched, each m involved in
// the relay sleeps for 5 seconds and then does the crash/exit itself.
// In expected operation, the last m has received the SIGQUIT and run
// crash/exit and the process is gone, all long before any of the
// 5-second sleeps have finished.
print("\n-----\n\n")
raiseproc(_SIGQUIT)
usleep(5 * 1000 * 1000)
// Only push runtime.sigpanic if pc != 0.
// If pc == 0, probably panicked because of a
// call to a nil func. Not pushing that onto sp will
// make the trace look like a call to runtime.sigpanic instead.
// (Otherwise the trace will end at runtime.sigpanic and we
// won't get to see who faulted.)
if pc != 0 {
if sys.RegSize > sys.PtrSize {
sp -= sys.PtrSize
*(*uintptr)(unsafe.Pointer(sp)) = 0
}
crash()
sp -= sys.PtrSize
*(*uintptr)(unsafe.Pointer(sp)) = pc
c.set_esp(uint32(sp))
}
exit(2)
c.set_eip(uint32(funcPC(sigpanic)))
}
src/runtime/signal_amd64x.go
View file @ 159a90b9
......@@ -36,175 +36,56 @@ func dumpregs(c *sigctxt) {
print("gs ", hex(c.gs()), "\n")
}
var crashing int32
// May run during STW, so write barriers are not allowed.
//
//go:nowritebarrierrec
func sighandler(sig uint32, info *siginfo, ctxt unsafe.Pointer, gp *g) {
_g_ := getg()
c := &sigctxt{info, ctxt}
if sig == _SIGPROF {
sigprof(uintptr(c.rip()), uintptr(c.rsp()), 0, gp, _g_.m)
return
}
func (c *sigctxt) sigpc() uintptr { return uintptr(c.rip()) }
func (c *sigctxt) sigsp() uintptr { return uintptr(c.rsp()) }
func (c *sigctxt) siglr() uintptr { return 0 }
func (c *sigctxt) fault() uintptr { return uintptr(c.sigaddr()) }
// preparePanic sets up the stack to look like a call to sigpanic.
func (c *sigctxt) preparePanic(sig uint32, gp *g) {
if GOOS == "darwin" {
// x86-64 has 48-bit virtual addresses. The top 16 bits must echo bit 47.
// The hardware delivers a different kind of fault for a malformed address
// than it does for an attempt to access a valid but unmapped address.
// OS X 10.9.2 mishandles the malformed address case, making it look like
// a user-generated signal (like someone ran kill -SEGV ourpid).
// We pass user-generated signals to os/signal, or else ignore them.
// Doing that here - and returning to the faulting code - results in an
// infinite loop. It appears the best we can do is rewrite what the kernel
// delivers into something more like the truth. The address used below
// has very little chance of being the one that caused the fault, but it is
// malformed, it is clearly not a real pointer, and if it does get printed
// in real life, people will probably search for it and find this code.
// There are no Google hits for b01dfacedebac1e or 0xb01dfacedebac1e
// as I type this comment.
if sig == _SIGSEGV && c.sigcode() == _SI_USER {
c.set_sigcode(_SI_USER + 1)
c.set_sigaddr(0xb01dfacedebac1e)
}
}
flags := int32(_SigThrow)
if sig < uint32(len(sigtable)) {
flags = sigtable[sig].flags
}
if c.sigcode() != _SI_USER && flags&_SigPanic != 0 {
// Make it look like a call to the signal func.
// Have to pass arguments out of band since
// augmenting the stack frame would break
// the unwinding code.
gp.sig = sig
gp.sigcode0 = uintptr(c.sigcode())
gp.sigcode1 = uintptr(c.sigaddr())
gp.sigpc = uintptr(c.rip())
if GOOS == "darwin" {
// Work around Leopard bug that doesn't set FPE_INTDIV.
// Look at instruction to see if it is a divide.
// Not necessary in Snow Leopard (si_code will be != 0).
if sig == _SIGFPE && gp.sigcode0 == 0 {
pc := (*[4]byte)(unsafe.Pointer(gp.sigpc))
i := 0
if pc[i]&0xF0 == 0x40 { // 64-bit REX prefix
i++
} else if pc[i] == 0x66 { // 16-bit instruction prefix
i++
}
if pc[i] == 0xF6 || pc[i] == 0xF7 {
gp.sigcode0 = _FPE_INTDIV
}
// Work around Leopard bug that doesn't set FPE_INTDIV.
// Look at instruction to see if it is a divide.
// Not necessary in Snow Leopard (si_code will be != 0).
if sig == _SIGFPE && gp.sigcode0 == 0 {
pc := (*[4]byte)(unsafe.Pointer(gp.sigpc))
i := 0
if pc[i]&0xF0 == 0x40 { // 64-bit REX prefix
i++
} else if pc[i] == 0x66 { // 16-bit instruction prefix
i++
}
}
pc := uintptr(c.rip())
sp := uintptr(c.rsp())
// If we don't recognize the PC as code
// but we do recognize the top pointer on the stack as code,
// then assume this was a call to non-code and treat like
// pc == 0, to make unwinding show the context.
if pc != 0 && findfunc(pc) == nil && findfunc(*(*uintptr)(unsafe.Pointer(sp))) != nil {
pc = 0
}
// Only push runtime.sigpanic if pc != 0.
// If pc == 0, probably panicked because of a
// call to a nil func. Not pushing that onto sp will
// make the trace look like a call to runtime.sigpanic instead.
// (Otherwise the trace will end at runtime.sigpanic and we
// won't get to see who faulted.)
if pc != 0 {
if sys.RegSize > sys.PtrSize {
sp -= sys.PtrSize
*(*uintptr)(unsafe.Pointer(sp)) = 0
if pc[i] == 0xF6 || pc[i] == 0xF7 {
gp.sigcode0 = _FPE_INTDIV
}
sp -= sys.PtrSize
*(*uintptr)(unsafe.Pointer(sp)) = pc
c.set_rsp(uint64(sp))
}
c.set_rip(uint64(funcPC(sigpanic)))
return
}
if c.sigcode() == _SI_USER || flags&_SigNotify != 0 {
if sigsend(sig) {
return
}
}
if c.sigcode() == _SI_USER && signal_ignored(sig) {
return
}
if flags&_SigKill != 0 {
dieFromSignal(int32(sig))
}
if flags&_SigThrow == 0 {
return
}
_g_.m.throwing = 1
_g_.m.caughtsig.set(gp)
if crashing == 0 {
startpanic()
}
if sig < uint32(len(sigtable)) {
print(sigtable[sig].name, "\n")
} else {
print("Signal ", sig, "\n")
}
print("PC=", hex(c.rip()), " m=", _g_.m.id, "\n")
if _g_.m.lockedg != nil && _g_.m.ncgo > 0 && gp == _g_.m.g0 {
print("signal arrived during cgo execution\n")
gp = _g_.m.lockedg
}
print("\n")
pc := uintptr(c.rip())
sp := uintptr(c.rsp())
level, _, docrash := gotraceback()
if level > 0 {
goroutineheader(gp)
tracebacktrap(uintptr(c.rip()), uintptr(c.rsp()), 0, gp)
if crashing > 0 && gp != _g_.m.curg && _g_.m.curg != nil && readgstatus(_g_.m.curg)&^_Gscan == _Grunning {
// tracebackothers on original m skipped this one; trace it now.
goroutineheader(_g_.m.curg)
traceback(^uintptr(0), ^uintptr(0), 0, gp)
} else if crashing == 0 {
tracebackothers(gp)
print("\n")
}
dumpregs(c)
// If we don't recognize the PC as code
// but we do recognize the top pointer on the stack as code,
// then assume this was a call to non-code and treat like
// pc == 0, to make unwinding show the context.
if pc != 0 && findfunc(pc) == nil && findfunc(*(*uintptr)(unsafe.Pointer(sp))) != nil {
pc = 0
}
if docrash {
crashing++
if crashing < sched.mcount {
// There are other m's that need to dump their stacks.
// Relay SIGQUIT to the next m by sending it to the current process.
// All m's that have already received SIGQUIT have signal masks blocking
// receipt of any signals, so the SIGQUIT will go to an m that hasn't seen it yet.
// When the last m receives the SIGQUIT, it will fall through to the call to
// crash below. Just in case the relaying gets botched, each m involved in
// the relay sleeps for 5 seconds and then does the crash/exit itself.
// In expected operation, the last m has received the SIGQUIT and run
// crash/exit and the process is gone, all long before any of the
// 5-second sleeps have finished.
print("\n-----\n\n")
raiseproc(_SIGQUIT)
usleep(5 * 1000 * 1000)
// Only push runtime.sigpanic if pc != 0.
// If pc == 0, probably panicked because of a
// call to a nil func. Not pushing that onto sp will
// make the trace look like a call to runtime.sigpanic instead.
// (Otherwise the trace will end at runtime.sigpanic and we
// won't get to see who faulted.)
if pc != 0 {
if sys.RegSize > sys.PtrSize {
sp -= sys.PtrSize
*(*uintptr)(unsafe.Pointer(sp)) = 0
}
crash()
sp -= sys.PtrSize
*(*uintptr)(unsafe.Pointer(sp)) = pc
c.set_rsp(uint64(sp))
}
exit(2)
c.set_rip(uint64(funcPC(sigpanic)))
}
src/runtime/signal_arm.go
View file @ 159a90b9
......@@ -32,139 +32,40 @@ func dumpregs(c *sigctxt) {
print("fault ", hex(c.fault()), "\n")
}
var crashing int32
// May run during STW, so write barriers are not allowed.
//
//go:nowritebarrierrec
func sighandler(sig uint32, info *siginfo, ctxt unsafe.Pointer, gp *g) {
_g_ := getg()
c := &sigctxt{info, ctxt}
if sig == _SIGPROF {
sigprof(uintptr(c.pc()), uintptr(c.sp()), uintptr(c.lr()), gp, _g_.m)
return
}
flags := int32(_SigThrow)
if sig < uint32(len(sigtable)) {
flags = sigtable[sig].flags
}
if c.sigcode() != _SI_USER && flags&_SigPanic != 0 {
// Make it look like a call to the signal func.
// Have to pass arguments out of band since
// augmenting the stack frame would break
// the unwinding code.
gp.sig = sig
gp.sigcode0 = uintptr(c.sigcode())
gp.sigcode1 = uintptr(c.fault())
gp.sigpc = uintptr(c.pc())
// 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.
sp := c.sp() - 4
c.set_sp(sp)
*(*uint32)(unsafe.Pointer(uintptr(sp))) = c.lr()
pc := gp.sigpc
// If we don't recognize the PC as code
// but we do recognize the link register as code,
// then assume this was a call to non-code and treat like
// pc == 0, to make unwinding show the context.
if pc != 0 && findfunc(pc) == nil && findfunc(uintptr(c.lr())) != nil {
pc = 0
}
// 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 pc != 0 {
c.set_lr(uint32(pc))
}
// In case we are panicking from external C code
c.set_r10(uint32(uintptr(unsafe.Pointer(gp))))
c.set_pc(uint32(funcPC(sigpanic)))
return
}
if c.sigcode() == _SI_USER || flags&_SigNotify != 0 {
if sigsend(sig) {
return
}
}
if c.sigcode() == _SI_USER && signal_ignored(sig) {
return
}
if flags&_SigKill != 0 {
dieFromSignal(int32(sig))
}
if flags&_SigThrow == 0 {
return
}
_g_.m.throwing = 1
_g_.m.caughtsig.set(gp)
if crashing == 0 {
startpanic()
}
if sig < uint32(len(sigtable)) {
print(sigtable[sig].name, "\n")
} else {
print("Signal ", sig, "\n")
}
print("PC=", hex(c.pc()), " m=", _g_.m.id, "\n")
if _g_.m.lockedg != nil && _g_.m.ncgo > 0 && gp == _g_.m.g0 {
print("signal arrived during cgo execution\n")
gp = _g_.m.lockedg
}
print("\n")
level, _, docrash := gotraceback()
if level > 0 {
goroutineheader(gp)
tracebacktrap(uintptr(c.pc()), uintptr(c.sp()), uintptr(c.lr()), gp)
if crashing > 0 && gp != _g_.m.curg && _g_.m.curg != nil && readgstatus(_g_.m.curg)&^_Gscan == _Grunning {
// tracebackothers on original m skipped this one; trace it now.
goroutineheader(_g_.m.curg)
traceback(^uintptr(0), ^uintptr(0), 0, gp)
} else if crashing == 0 {
tracebackothers(gp)
print("\n")
}
dumpregs(c)
func (c *sigctxt) sigpc() uintptr { return uintptr(c.pc()) }
func (c *sigctxt) sigsp() uintptr { return uintptr(c.sp()) }
func (c *sigctxt) siglr() uintptr { return uintptr(c.lr()) }
// preparePanic sets up the stack to look like a call to sigpanic.
func (c *sigctxt) preparePanic(sig uint32, gp *g) {
// 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.
sp := c.sp() - 4
c.set_sp(sp)
*(*uint32)(unsafe.Pointer(uintptr(sp))) = c.lr()
pc := gp.sigpc
// If we don't recognize the PC as code
// but we do recognize the link register as code,
// then assume this was a call to non-code and treat like
// pc == 0, to make unwinding show the context.
if pc != 0 && findfunc(pc) == nil && findfunc(uintptr(c.lr())) != nil {
pc = 0
}
if docrash {
crashing++
if crashing < sched.mcount {
// There are other m's that need to dump their stacks.
// Relay SIGQUIT to the next m by sending it to the current process.
// All m's that have already received SIGQUIT have signal masks blocking
// receipt of any signals, so the SIGQUIT will go to an m that hasn't seen it yet.
// When the last m receives the SIGQUIT, it will fall through to the call to
// crash below. Just in case the relaying gets botched, each m involved in
// the relay sleeps for 5 seconds and then does the crash/exit itself.
// In expected operation, the last m has received the SIGQUIT and run
// crash/exit and the process is gone, all long before any of the
// 5-second sleeps have finished.
print("\n-----\n\n")
raiseproc(_SIGQUIT)
usleep(5 * 1000 * 1000)
}
crash()
// 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 pc != 0 {
c.set_lr(uint32(pc))
}
exit(2)
// In case we are panicking from external C code
c.set_r10(uint32(uintptr(unsafe.Pointer(gp))))
c.set_pc(uint32(funcPC(sigpanic)))
}
src/runtime/signal_arm64.go
View file @ 159a90b9
......@@ -48,139 +48,40 @@ func dumpregs(c *sigctxt) {
print("fault ", hex(c.fault()), "\n")
}
var crashing int32
// May run during STW, so write barriers are not allowed.
//
//go:nowritebarrierrec
func sighandler(sig uint32, info *siginfo, ctxt unsafe.Pointer, gp *g) {
_g_ := getg()
c := &sigctxt{info, ctxt}
if sig == _SIGPROF {
sigprof(uintptr(c.pc()), uintptr(c.sp()), uintptr(c.lr()), gp, _g_.m)
return
}
flags := int32(_SigThrow)
if sig < uint32(len(sigtable)) {
flags = sigtable[sig].flags
}
if c.sigcode() != _SI_USER && flags&_SigPanic != 0 {
// Make it look like a call to the signal func.
// Have to pass arguments out of band since
// augmenting the stack frame would break
// the unwinding code.
gp.sig = sig
gp.sigcode0 = uintptr(c.sigcode())
gp.sigcode1 = uintptr(c.fault())
gp.sigpc = uintptr(c.pc())
// 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.
sp := c.sp() - sys.SpAlign // needs only sizeof uint64, but must align the stack
c.set_sp(sp)
*(*uint64)(unsafe.Pointer(uintptr(sp))) = c.lr()
pc := gp.sigpc
// If we don't recognize the PC as code
// but we do recognize the link register as code,
// then assume this was a call to non-code and treat like
// pc == 0, to make unwinding show the context.
if pc != 0 && findfunc(pc) == nil && findfunc(uintptr(c.lr())) != nil {
pc = 0
}
// 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 pc != 0 {
c.set_lr(uint64(pc))
}
// In case we are panicking from external C code
c.set_r28(uint64(uintptr(unsafe.Pointer(gp))))
c.set_pc(uint64(funcPC(sigpanic)))
return
}
if c.sigcode() == _SI_USER || flags&_SigNotify != 0 {
if sigsend(sig) {
return
}
}
if c.sigcode() == _SI_USER && signal_ignored(sig) {
return
}
if flags&_SigKill != 0 {
dieFromSignal(int32(sig))
}
if flags&_SigThrow == 0 {
return
}
_g_.m.throwing = 1
_g_.m.caughtsig.set(gp)
if crashing == 0 {
startpanic()
}
if sig < uint32(len(sigtable)) {
print(sigtable[sig].name, "\n")
} else {
print("Signal ", sig, "\n")
}
print("PC=", hex(c.pc()), " m=", _g_.m.id, "\n")
if _g_.m.lockedg != nil && _g_.m.ncgo > 0 && gp == _g_.m.g0 {
print("signal arrived during cgo execution\n")
gp = _g_.m.lockedg
}
print("\n")
level, _, docrash := gotraceback()
if level > 0 {
goroutineheader(gp)
tracebacktrap(uintptr(c.pc()), uintptr(c.sp()), uintptr(c.lr()), gp)
if crashing > 0 && gp != _g_.m.curg && _g_.m.curg != nil && readgstatus(_g_.m.curg)&^_Gscan == _Grunning {
// tracebackothers on original m skipped this one; trace it now.
goroutineheader(_g_.m.curg)
traceback(^uintptr(0), ^uintptr(0), 0, gp)
} else if crashing == 0 {
tracebackothers(gp)
print("\n")
}
dumpregs(c)
func (c *sigctxt) sigpc() uintptr { return uintptr(c.pc()) }
func (c *sigctxt) sigsp() uintptr { return uintptr(c.sp()) }
func (c *sigctxt) siglr() uintptr { return uintptr(c.lr()) }
// preparePanic sets up the stack to look like a call to sigpanic.
func (c *sigctxt) preparePanic(sig uint32, gp *g) {
// 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.
sp := c.sp() - sys.SpAlign // needs only sizeof uint64, but must align the stack
c.set_sp(sp)
*(*uint64)(unsafe.Pointer(uintptr(sp))) = c.lr()
pc := gp.sigpc
// If we don't recognize the PC as code
// but we do recognize the link register as code,
// then assume this was a call to non-code and treat like
// pc == 0, to make unwinding show the context.
if pc != 0 && findfunc(pc) == nil && findfunc(uintptr(c.lr())) != nil {
pc = 0
}
if docrash {
crashing++
if crashing < sched.mcount {
// There are other m's that need to dump their stacks.
// Relay SIGQUIT to the next m by sending it to the current process.
// All m's that have already received SIGQUIT have signal masks blocking
// receipt of any signals, so the SIGQUIT will go to an m that hasn't seen it yet.
// When the last m receives the SIGQUIT, it will fall through to the call to
// crash below. Just in case the relaying gets botched, each m involved in
// the relay sleeps for 5 seconds and then does the crash/exit itself.
// In expected operation, the last m has received the SIGQUIT and run
// crash/exit and the process is gone, all long before any of the
// 5-second sleeps have finished.
print("\n-----\n\n")
raiseproc(_SIGQUIT)
usleep(5 * 1000 * 1000)
}
crash()
// 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 pc != 0 {
c.set_lr(uint64(pc))
}
exit(2)
// In case we are panicking from external C code
c.set_r28(uint64(uintptr(unsafe.Pointer(gp))))
c.set_pc(uint64(funcPC(sigpanic)))
}
src/runtime/signal_darwin_amd64.go
View file @ 159a90b9
......@@ -60,5 +60,25 @@ func (c *sigctxt) fixsigcode(sig uint32) {
// SIGTRAP on something other than INT 3.
c.set_sigcode(_SI_USER)
}
case _SIGSEGV:
// x86-64 has 48-bit virtual addresses. The top 16 bits must echo bit 47.
// The hardware delivers a different kind of fault for a malformed address
// than it does for an attempt to access a valid but unmapped address.
// OS X 10.9.2 mishandles the malformed address case, making it look like
// a user-generated signal (like someone ran kill -SEGV ourpid).
// We pass user-generated signals to os/signal, or else ignore them.
// Doing that here - and returning to the faulting code - results in an
// infinite loop. It appears the best we can do is rewrite what the kernel
// delivers into something more like the truth. The address used below
// has very little chance of being the one that caused the fault, but it is
// malformed, it is clearly not a real pointer, and if it does get printed
// in real life, people will probably search for it and find this code.
// There are no Google hits for b01dfacedebac1e or 0xb01dfacedebac1e
// as I type this comment.
if c.sigcode() == _SI_USER {
c.set_sigcode(_SI_USER + 1)
c.set_sigaddr(0xb01dfacedebac1e)
}
}
}
src/runtime/signal_linux_s390x.go
View file @ 159a90b9
......@@ -70,139 +70,42 @@ func dumpregs(c *sigctxt) {
print("link ", hex(c.link()), "\n")
}
var crashing int32
// May run during STW, so write barriers are not allowed.
//
//go:nowritebarrierrec
func sighandler(sig uint32, info *siginfo, ctxt unsafe.Pointer, gp *g) {
_g_ := getg()
c := &sigctxt{info, ctxt}
if sig == _SIGPROF {
sigprof(uintptr(c.pc()), uintptr(c.sp()), uintptr(c.link()), gp, _g_.m)
return
}
flags := int32(_SigThrow)
if sig < uint32(len(sigtable)) {
flags = sigtable[sig].flags
}
if c.sigcode() != _SI_USER && flags&_SigPanic != 0 {
// Make it look like a call to the signal func.
// Have to pass arguments out of band since
// augmenting the stack frame would break
// the unwinding code.
gp.sig = sig
gp.sigcode0 = uintptr(c.sigcode())
gp.sigcode1 = uintptr(c.sigaddr())
gp.sigpc = uintptr(c.pc())
// We arrange link, and pc to pretend the panicking
// function calls sigpanic directly.
// Always save LINK to stack so that panics in leaf
// functions are correctly handled. This smashes
// the stack frame but we're not going back there
// anyway.
sp := c.sp() - sys.MinFrameSize
c.set_sp(sp)
*(*uint64)(unsafe.Pointer(uintptr(sp))) = c.link()
pc := uintptr(gp.sigpc)
// If we don't recognize the PC as code
// but we do recognize the link register as code,
// then assume this was a call to non-code and treat like
// pc == 0, to make unwinding show the context.
if pc != 0 && findfunc(pc) == nil && findfunc(uintptr(c.link())) != nil {
pc = 0
}
// 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 pc != 0 {
c.set_link(uint64(pc))
}
// In case we are panicking from external C code
c.set_r0(0)
c.set_r13(uint64(uintptr(unsafe.Pointer(gp))))
c.set_pc(uint64(funcPC(sigpanic)))
return
}
if c.sigcode() == _SI_USER || flags&_SigNotify != 0 {
if sigsend(sig) {
return
}
}
if c.sigcode() == _SI_USER && signal_ignored(sig) {
return
}
if flags&_SigKill != 0 {
dieFromSignal(int32(sig))
}
if flags&_SigThrow == 0 {
return
}
_g_.m.throwing = 1
_g_.m.caughtsig.set(gp)
if crashing == 0 {
startpanic()
}
if sig < uint32(len(sigtable)) {
print(sigtable[sig].name, "\n")
} else {
print("Signal ", sig, "\n")
}
print("PC=", hex(c.pc()), " m=", _g_.m.id, "\n")
if _g_.m.lockedg != nil && _g_.m.ncgo > 0 && gp == _g_.m.g0 {
print("signal arrived during cgo execution\n")
gp = _g_.m.lockedg
}
print("\n")
level, _, docrash := gotraceback()
if level > 0 {
goroutineheader(gp)
tracebacktrap(uintptr(c.pc()), uintptr(c.sp()), uintptr(c.link()), gp)
if crashing > 0 && gp != _g_.m.curg && _g_.m.curg != nil && readgstatus(_g_.m.curg)&^_Gscan == _Grunning {
// tracebackothers on original m skipped this one; trace it now.
goroutineheader(_g_.m.curg)
traceback(^uintptr(0), ^uintptr(0), 0, gp)
} else if crashing == 0 {
tracebackothers(gp)
print("\n")
}
dumpregs(c)
func (c *sigctxt) sigpc() uintptr { return uintptr(c.pc()) }
func (c *sigctxt) sigsp() uintptr { return uintptr(c.sp()) }
func (c *sigctxt) siglr() uintptr { return uintptr(c.link()) }
func (c *sigctxt) fault() uintptr { return uintptr(c.sigaddr()) }
// preparePanic sets up the stack to look like a call to sigpanic.
func (c *sigctxt) preparePanic(sig uint32, gp *g) {
// We arrange link, and pc to pretend the panicking
// function calls sigpanic directly.
// Always save LINK to stack so that panics in leaf
// functions are correctly handled. This smashes
// the stack frame but we're not going back there
// anyway.
sp := c.sp() - sys.MinFrameSize
c.set_sp(sp)
*(*uint64)(unsafe.Pointer(uintptr(sp))) = c.link()
pc := uintptr(gp.sigpc)
// If we don't recognize the PC as code
// but we do recognize the link register as code,
// then assume this was a call to non-code and treat like
// pc == 0, to make unwinding show the context.
if pc != 0 && findfunc(pc) == nil && findfunc(uintptr(c.link())) != nil {
pc = 0
}
if docrash {
crashing++
if crashing < sched.mcount {
// There are other m's that need to dump their stacks.
// Relay SIGQUIT to the next m by sending it to the current process.
// All m's that have already received SIGQUIT have signal masks blocking
// receipt of any signals, so the SIGQUIT will go to an m that hasn't seen it yet.
// When the last m receives the SIGQUIT, it will fall through to the call to
// crash below. Just in case the relaying gets botched, each m involved in
// the relay sleeps for 5 seconds and then does the crash/exit itself.
// In expected operation, the last m has received the SIGQUIT and run
// crash/exit and the process is gone, all long before any of the
// 5-second sleeps have finished.
print("\n-----\n\n")
raiseproc(_SIGQUIT)
usleep(5 * 1000 * 1000)
}
crash()
// 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 pc != 0 {
c.set_link(uint64(pc))
}
exit(2)
// In case we are panicking from external C code
c.set_r0(0)
c.set_r13(uint64(uintptr(unsafe.Pointer(gp))))
c.set_pc(uint64(funcPC(sigpanic)))
}
src/runtime/signal_mips64x.go
View file @ 159a90b9
......@@ -51,138 +51,41 @@ func dumpregs(c *sigctxt) {
print("hi ", hex(c.hi()), "\n")
}
var crashing int32
// May run during STW, so write barriers are not allowed.
//
//go:nowritebarrierrec
func sighandler(sig uint32, info *siginfo, ctxt unsafe.Pointer, gp *g) {
_g_ := getg()
c := &sigctxt{info, ctxt}
if sig == _SIGPROF {
sigprof(uintptr(c.pc()), uintptr(c.sp()), uintptr(c.link()), gp, _g_.m)
return
}
flags := int32(_SigThrow)
if sig < uint32(len(sigtable)) {
flags = sigtable[sig].flags
}
if c.sigcode() != _SI_USER && flags&_SigPanic != 0 {
// Make it look like a call to the signal func.
// Have to pass arguments out of band since
// augmenting the stack frame would break
// the unwinding code.
gp.sig = sig
gp.sigcode0 = uintptr(c.sigcode())
gp.sigcode1 = uintptr(c.sigaddr())
gp.sigpc = uintptr(c.pc())
// We arrange link, and pc to pretend the panicking
// function calls sigpanic directly.
// Always save LINK to stack so that panics in leaf
// functions are correctly handled. This smashes
// the stack frame but we're not going back there
// anyway.
sp := c.sp() - sys.PtrSize
c.set_sp(sp)
*(*uint64)(unsafe.Pointer(uintptr(sp))) = c.link()
pc := gp.sigpc
// If we don't recognize the PC as code
// but we do recognize the link register as code,
// then assume this was a call to non-code and treat like
// pc == 0, to make unwinding show the context.
if pc != 0 && findfunc(pc) == nil && findfunc(uintptr(c.link())) != nil {
pc = 0
}
// 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 pc != 0 {
c.set_link(uint64(pc))
}
// In case we are panicking from external C code
c.set_r30(uint64(uintptr(unsafe.Pointer(gp))))
c.set_pc(uint64(funcPC(sigpanic)))
return
}
if c.sigcode() == _SI_USER || flags&_SigNotify != 0 {
if sigsend(sig) {
return
}
}
if c.sigcode() == _SI_USER && signal_ignored(sig) {
return
}
if flags&_SigKill != 0 {
dieFromSignal(int32(sig))
}
if flags&_SigThrow == 0 {
return
}
_g_.m.throwing = 1
_g_.m.caughtsig.set(gp)
if crashing == 0 {
startpanic()
}
if sig < uint32(len(sigtable)) {
print(sigtable[sig].name, "\n")
} else {
print("Signal ", sig, "\n")
}
print("PC=", hex(c.pc()), " m=", _g_.m.id, "\n")
if _g_.m.lockedg != nil && _g_.m.ncgo > 0 && gp == _g_.m.g0 {
print("signal arrived during cgo execution\n")
gp = _g_.m.lockedg
}
print("\n")
level, _, docrash := gotraceback()
if level > 0 {
goroutineheader(gp)
tracebacktrap(uintptr(c.pc()), uintptr(c.sp()), uintptr(c.link()), gp)
if crashing > 0 && gp != _g_.m.curg && _g_.m.curg != nil && readgstatus(_g_.m.curg)&^_Gscan == _Grunning {
// tracebackothers on original m skipped this one; trace it now.
goroutineheader(_g_.m.curg)
traceback(^uintptr(0), ^uintptr(0), 0, gp)
} else if crashing == 0 {
tracebackothers(gp)
print("\n")
}
dumpregs(c)
func (c *sigctxt) sigpc() uintptr { return uintptr(c.pc()) }
func (c *sigctxt) sigsp() uintptr { return uintptr(c.sp()) }
func (c *sigctxt) siglr() uintptr { return uintptr(c.link()) }
func (c *sigctxt) fault() uintptr { return uintptr(c.sigaddr()) }
// preparePanic sets up the stack to look like a call to sigpanic.
func (c *sigctxt) preparePanic(sig uint32, gp *g) {
// We arrange link, and pc to pretend the panicking
// function calls sigpanic directly.
// Always save LINK to stack so that panics in leaf
// functions are correctly handled. This smashes
// the stack frame but we're not going back there
// anyway.
sp := c.sp() - sys.PtrSize
c.set_sp(sp)
*(*uint64)(unsafe.Pointer(uintptr(sp))) = c.link()
pc := gp.sigpc
// If we don't recognize the PC as code
// but we do recognize the link register as code,
// then assume this was a call to non-code and treat like
// pc == 0, to make unwinding show the context.
if pc != 0 && findfunc(pc) == nil && findfunc(uintptr(c.link())) != nil {
pc = 0
}
if docrash {
crashing++
if crashing < sched.mcount {
// There are other m's that need to dump their stacks.
// Relay SIGQUIT to the next m by sending it to the current process.
// All m's that have already received SIGQUIT have signal masks blocking
// receipt of any signals, so the SIGQUIT will go to an m that hasn't seen it yet.
// When the last m receives the SIGQUIT, it will fall through to the call to
// crash below. Just in case the relaying gets botched, each m involved in
// the relay sleeps for 5 seconds and then does the crash/exit itself.
// In expected operation, the last m has received the SIGQUIT and run
// crash/exit and the process is gone, all long before any of the
// 5-second sleeps have finished.
print("\n-----\n\n")
raiseproc(_SIGQUIT)
usleep(5 * 1000 * 1000)
}
crash()
// 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 pc != 0 {
c.set_link(uint64(pc))
}
exit(2)
// In case we are panicking from external C code
c.set_r30(uint64(uintptr(unsafe.Pointer(gp))))
c.set_pc(uint64(funcPC(sigpanic)))
}
src/runtime/signal_ppc64x.go
View file @ 159a90b9
......@@ -53,140 +53,42 @@ func dumpregs(c *sigctxt) {
print("trap ", hex(c.trap()), "\n")
}
var crashing int32
// May run during STW, so write barriers are not allowed.
//
//go:nowritebarrierrec
func sighandler(sig uint32, info *siginfo, ctxt unsafe.Pointer, gp *g) {
_g_ := getg()
c := &sigctxt{info, ctxt}
if sig == _SIGPROF {
sigprof(uintptr(c.pc()), uintptr(c.sp()), uintptr(c.link()), gp, _g_.m)
return
}
flags := int32(_SigThrow)
if sig < uint32(len(sigtable)) {
flags = sigtable[sig].flags
}
if c.sigcode() != _SI_USER && flags&_SigPanic != 0 {
// Make it look like a call to the signal func.
// Have to pass arguments out of band since
// augmenting the stack frame would break
// the unwinding code.
gp.sig = sig
gp.sigcode0 = uintptr(c.sigcode())
gp.sigcode1 = uintptr(c.fault())
gp.sigpc = uintptr(c.pc())
// We arrange link, and pc to pretend the panicking
// function calls sigpanic directly.
// Always save LINK to stack so that panics in leaf
// functions are correctly handled. This smashes
// the stack frame but we're not going back there
// anyway.
sp := c.sp() - sys.MinFrameSize
c.set_sp(sp)
*(*uint64)(unsafe.Pointer(uintptr(sp))) = c.link()
pc := gp.sigpc
// If we don't recognize the PC as code
// but we do recognize the link register as code,
// then assume this was a call to non-code and treat like
// pc == 0, to make unwinding show the context.
if pc != 0 && findfunc(pc) == nil && findfunc(uintptr(c.link())) != nil {
pc = 0
}
// 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 pc != 0 {
c.set_link(uint64(pc))
}
// In case we are panicking from external C code
c.set_r0(0)
c.set_r30(uint64(uintptr(unsafe.Pointer(gp))))
c.set_r12(uint64(funcPC(sigpanic)))
c.set_pc(uint64(funcPC(sigpanic)))
return
}
if c.sigcode() == _SI_USER || flags&_SigNotify != 0 {
if sigsend(sig) {
return
}
}
if c.sigcode() == _SI_USER && signal_ignored(sig) {
return
}
if flags&_SigKill != 0 {
dieFromSignal(int32(sig))
}
if flags&_SigThrow == 0 {
return
}
_g_.m.throwing = 1
_g_.m.caughtsig.set(gp)
if crashing == 0 {
startpanic()
}
if sig < uint32(len(sigtable)) {
print(sigtable[sig].name, "\n")
} else {
print("Signal ", sig, "\n")
}
print("PC=", hex(c.pc()), " m=", _g_.m.id, "\n")
if _g_.m.lockedg != nil && _g_.m.ncgo > 0 && gp == _g_.m.g0 {
print("signal arrived during cgo execution\n")
gp = _g_.m.lockedg
}
print("\n")
level, _, docrash := gotraceback()
if level > 0 {
goroutineheader(gp)
tracebacktrap(uintptr(c.pc()), uintptr(c.sp()), uintptr(c.link()), gp)
if crashing > 0 && gp != _g_.m.curg && _g_.m.curg != nil && readgstatus(_g_.m.curg)&^_Gscan == _Grunning {
// tracebackothers on original m skipped this one; trace it now.
goroutineheader(_g_.m.curg)
traceback(^uintptr(0), ^uintptr(0), 0, gp)
} else if crashing == 0 {
tracebackothers(gp)
print("\n")
}
dumpregs(c)
func (c *sigctxt) sigpc() uintptr { return uintptr(c.pc()) }
func (c *sigctxt) sigsp() uintptr { return uintptr(c.sp()) }
func (c *sigctxt) siglr() uintptr { return uintptr(c.link()) }
// preparePanic sets up the stack to look like a call to sigpanic.
func (c *sigctxt) preparePanic(sig uint32, gp *g) {
// We arrange link, and pc to pretend the panicking
// function calls sigpanic directly.
// Always save LINK to stack so that panics in leaf
// functions are correctly handled. This smashes
// the stack frame but we're not going back there
// anyway.
sp := c.sp() - sys.MinFrameSize
c.set_sp(sp)
*(*uint64)(unsafe.Pointer(uintptr(sp))) = c.link()
pc := gp.sigpc
// If we don't recognize the PC as code
// but we do recognize the link register as code,
// then assume this was a call to non-code and treat like
// pc == 0, to make unwinding show the context.
if pc != 0 && findfunc(pc) == nil && findfunc(uintptr(c.link())) != nil {
pc = 0
}
if docrash {
crashing++
if crashing < sched.mcount {
// There are other m's that need to dump their stacks.
// Relay SIGQUIT to the next m by sending it to the current process.
// All m's that have already received SIGQUIT have signal masks blocking
// receipt of any signals, so the SIGQUIT will go to an m that hasn't seen it yet.
// When the last m receives the SIGQUIT, it will fall through to the call to
// crash below. Just in case the relaying gets botched, each m involved in
// the relay sleeps for 5 seconds and then does the crash/exit itself.
// In expected operation, the last m has received the SIGQUIT and run
// crash/exit and the process is gone, all long before any of the
// 5-second sleeps have finished.
print("\n-----\n\n")
raiseproc(_SIGQUIT)
usleep(5 * 1000 * 1000)
}
crash()
// 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 pc != 0 {
c.set_link(uint64(pc))
}
exit(2)
// In case we are panicking from external C code
c.set_r0(0)
c.set_r30(uint64(uintptr(unsafe.Pointer(gp))))
c.set_r12(uint64(funcPC(sigpanic)))
c.set_pc(uint64(funcPC(sigpanic)))
}
src/runtime/signal_sighandler.go 0 → 100644
View file @ 159a90b9
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// +build darwin dragonfly freebsd linux nacl netbsd openbsd solaris
package runtime
import (
"unsafe"
)
// crashing is the number of m's we have waited for when implementing
// GOTRACEBACK=crash when a signal is received.
var crashing int32
// sighandler is invoked when a signal occurs. The global g will be
// set to a gsignal goroutine and we will be running on the alternate
// signal stack. The parameter g will be the value of the global g
// when the signal occurred. The sig, info, and ctxt parameters are
// from the system signal handler: they are the parameters passed when
// the SA is passed to the sigaction system call.
//
// The garbage collector may have stopped the world, so write barriers
// are not allowed.
//
//go:nowritebarrierrec
func sighandler(sig uint32, info *siginfo, ctxt unsafe.Pointer, gp *g) {
_g_ := getg()
c := &sigctxt{info, ctxt}
if sig == _SIGPROF {
sigprof(c.sigpc(), c.sigsp(), c.siglr(), gp, _g_.m)
return
}
flags := int32(_SigThrow)
if sig < uint32(len(sigtable)) {
flags = sigtable[sig].flags
}
if c.sigcode() != _SI_USER && flags&_SigPanic != 0 {
// The signal is going to cause a panic.
// Arrange the stack so that it looks like the point
// where the signal occurred made a call to the
// function sigpanic. Then set the PC to sigpanic.
// Have to pass arguments out of band since
// augmenting the stack frame would break
// the unwinding code.
gp.sig = sig
gp.sigcode0 = uintptr(c.sigcode())
gp.sigcode1 = uintptr(c.fault())
gp.sigpc = c.sigpc()
c.preparePanic(sig, gp)
return
}
if c.sigcode() == _SI_USER || flags&_SigNotify != 0 {
if sigsend(sig) {
return
}
}
if c.sigcode() == _SI_USER && signal_ignored(sig) {
return
}
if flags&_SigKill != 0 {
dieFromSignal(int32(sig))
}
if flags&_SigThrow == 0 {
return
}
_g_.m.throwing = 1
_g_.m.caughtsig.set(gp)
if crashing == 0 {
startpanic()
}
if sig < uint32(len(sigtable)) {
print(sigtable[sig].name, "\n")
} else {
print("Signal ", sig, "\n")
}
print("PC=", hex(c.sigpc()), " m=", _g_.m.id, "\n")
if _g_.m.lockedg != nil && _g_.m.ncgo > 0 && gp == _g_.m.g0 {
print("signal arrived during cgo execution\n")
gp = _g_.m.lockedg
}
print("\n")
level, _, docrash := gotraceback()
if level > 0 {
goroutineheader(gp)
tracebacktrap(c.sigpc(), c.sigsp(), c.siglr(), gp)
if crashing > 0 && gp != _g_.m.curg && _g_.m.curg != nil && readgstatus(_g_.m.curg)&^_Gscan == _Grunning {
// tracebackothers on original m skipped this one; trace it now.
goroutineheader(_g_.m.curg)
traceback(^uintptr(0), ^uintptr(0), 0, gp)
} else if crashing == 0 {
tracebackothers(gp)
print("\n")
}
dumpregs(c)
}
if docrash {
crashing++
if crashing < sched.mcount {
// There are other m's that need to dump their stacks.
// Relay SIGQUIT to the next m by sending it to the current process.
// All m's that have already received SIGQUIT have signal masks blocking
// receipt of any signals, so the SIGQUIT will go to an m that hasn't seen it yet.
// When the last m receives the SIGQUIT, it will fall through to the call to
// crash below. Just in case the relaying gets botched, each m involved in
// the relay sleeps for 5 seconds and then does the crash/exit itself.
// In expected operation, the last m has received the SIGQUIT and run
// crash/exit and the process is gone, all long before any of the
// 5-second sleeps have finished.
print("\n-----\n\n")
raiseproc(_SIGQUIT)
usleep(5 * 1000 * 1000)
}
crash()
}
exit(2)
}
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