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// 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 aix darwin dragonfly freebsd hurd 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
// testSigtrap is used by the runtime tests. If non-nil, it is called
// on SIGTRAP. If it returns true, the normal behavior on SIGTRAP is
// suppressed.
var testSigtrap func(info *_siginfo_t, ctxt *sigctxt, gp *g) bool
// 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_t, ctxt unsafe.Pointer, gp *g) {
_g_ := getg()
c := &sigctxt{info, ctxt}
sigfault, sigpc := getSiginfo(info, ctxt)
if sig == _SIGURG && usestackmaps {
// We may be signaled to do a stack scan.
// The signal delivery races with enter/exitsyscall.
// We may be on g0 stack now. gp.m.curg is the g we
// want to scan.
// If we're not on g stack, give up. The sender will
// try again later.
// If we're not stopped at a safepoint (doscanstack will
// return false), also give up.
if s := readgstatus(gp.m.curg); s == _Gscansyscall {
if gp == gp.m.curg {
if doscanstack(gp, (*gcWork)(unsafe.Pointer(gp.scangcw))) {
gp.gcscanvalid = true
gp.gcscandone = true
}
}
gp.m.curg.scangcw = 0
notewakeup(&gp.m.scannote)
return
}
}
if sig == _SIGPROF {
sigprof(sigpc, gp, _g_.m)
return
}
if sig == _SIGTRAP && testSigtrap != nil && testSigtrap(info, (*sigctxt)(noescape(unsafe.Pointer(c))), gp) {
return
}
flags := int32(_SigThrow)
if sig < uint32(len(sigtable)) {
flags = sigtable[sig].flags
}
if flags&_SigPanic != 0 && gp.throwsplit {
// We can't safely sigpanic because it may grow the
// stack. Abort in the signal handler instead.
flags = (flags &^ _SigPanic) | _SigThrow
}
if isAbortPC(sigpc) {
// On many architectures, the abort function just
// causes a memory fault. Don't turn that into a panic.
flags = _SigThrow
}
if c.sigcode() != _SI_USER && flags&_SigPanic != 0 {
// Emulate gc by passing arguments out of band,
// although we don't really have to.
gp.sig = sig
gp.sigcode0 = uintptr(c.sigcode())
gp.sigcode1 = sigfault
gp.sigpc = sigpc
setg(gp)
// All signals were blocked due to the sigaction mask;
// unblock them.
var set sigset
sigfillset(&set)
sigprocmask(_SIG_UNBLOCK, &set, nil)
sigpanic()
throw("sigpanic returned")
}
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(sig)
}
if flags&_SigThrow == 0 {
return
}
_g_.m.throwing = 1
_g_.m.caughtsig.set(gp)
if crashing == 0 {
startpanic_m()
}
if sig < uint32(len(sigtable)) {
print(sigtable[sig].name, "\n")
} else {
print("Signal ", sig, "\n")
}
print("PC=", hex(sigpc), " m=", _g_.m.id, " sigcode=", c.sigcode(), "\n")
if _g_.m.lockedg != 0 && _g_.m.ncgo > 0 && gp == _g_.m.g0 {
print("signal arrived during cgo execution\n")
gp = _g_.m.lockedg.ptr()
}
print("\n")
level, _, docrash := gotraceback()
if level > 0 {
goroutineheader(gp)
traceback(0)
if crashing == 0 {
tracebackothers(gp)
print("\n")
}
dumpregs(info, ctxt)
}
if docrash {
crashing++
if crashing < mcount()-int32(extraMCount) {
// 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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