1 // Copyright 2013 The Go Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style
3 // license that can be found in the LICENSE file.
5 // +build amd64 amd64p32
6 // +build darwin dragonfly freebsd linux nacl netbsd openbsd solaris
14 func dumpregs(c *sigctxt) {
15 print("rax ", hex(c.rax()), "\n")
16 print("rbx ", hex(c.rbx()), "\n")
17 print("rcx ", hex(c.rcx()), "\n")
18 print("rdx ", hex(c.rdx()), "\n")
19 print("rdi ", hex(c.rdi()), "\n")
20 print("rsi ", hex(c.rsi()), "\n")
21 print("rbp ", hex(c.rbp()), "\n")
22 print("rsp ", hex(c.rsp()), "\n")
23 print("r8 ", hex(c.r8()), "\n")
24 print("r9 ", hex(c.r9()), "\n")
25 print("r10 ", hex(c.r10()), "\n")
26 print("r11 ", hex(c.r11()), "\n")
27 print("r12 ", hex(c.r12()), "\n")
28 print("r13 ", hex(c.r13()), "\n")
29 print("r14 ", hex(c.r14()), "\n")
30 print("r15 ", hex(c.r15()), "\n")
31 print("rip ", hex(c.rip()), "\n")
32 print("rflags ", hex(c.rflags()), "\n")
33 print("cs ", hex(c.cs()), "\n")
34 print("fs ", hex(c.fs()), "\n")
35 print("gs ", hex(c.gs()), "\n")
40 // May run during STW, so write barriers are not allowed.
42 func sighandler(sig uint32, info *siginfo, ctxt unsafe.Pointer, gp *g) {
44 c := &sigctxt{info, ctxt}
47 sigprof(uintptr(c.rip()), uintptr(c.rsp()), 0, gp, _g_.m)
52 // x86-64 has 48-bit virtual addresses. The top 16 bits must echo bit 47.
53 // The hardware delivers a different kind of fault for a malformed address
54 // than it does for an attempt to access a valid but unmapped address.
55 // OS X 10.9.2 mishandles the malformed address case, making it look like
56 // a user-generated signal (like someone ran kill -SEGV ourpid).
57 // We pass user-generated signals to os/signal, or else ignore them.
58 // Doing that here - and returning to the faulting code - results in an
59 // infinite loop. It appears the best we can do is rewrite what the kernel
60 // delivers into something more like the truth. The address used below
61 // has very little chance of being the one that caused the fault, but it is
62 // malformed, it is clearly not a real pointer, and if it does get printed
63 // in real life, people will probably search for it and find this code.
64 // There are no Google hits for b01dfacedebac1e or 0xb01dfacedebac1e
65 // as I type this comment.
66 if sig == _SIGSEGV && c.sigcode() == _SI_USER {
67 c.set_sigcode(_SI_USER + 1)
68 c.set_sigaddr(0xb01dfacedebac1e)
72 flags := int32(_SigThrow)
73 if sig < uint32(len(sigtable)) {
74 flags = sigtable[sig].flags
76 if c.sigcode() != _SI_USER && flags&_SigPanic != 0 {
77 // Make it look like a call to the signal func.
78 // Have to pass arguments out of band since
79 // augmenting the stack frame would break
80 // the unwinding code.
82 gp.sigcode0 = uintptr(c.sigcode())
83 gp.sigcode1 = uintptr(c.sigaddr())
84 gp.sigpc = uintptr(c.rip())
87 // Work around Leopard bug that doesn't set FPE_INTDIV.
88 // Look at instruction to see if it is a divide.
89 // Not necessary in Snow Leopard (si_code will be != 0).
90 if sig == _SIGFPE && gp.sigcode0 == 0 {
91 pc := (*[4]byte)(unsafe.Pointer(gp.sigpc))
93 if pc[i]&0xF0 == 0x40 { // 64-bit REX prefix
95 } else if pc[i] == 0x66 { // 16-bit instruction prefix
98 if pc[i] == 0xF6 || pc[i] == 0xF7 {
99 gp.sigcode0 = _FPE_INTDIV
104 pc := uintptr(c.rip())
105 sp := uintptr(c.rsp())
107 // If we don't recognize the PC as code
108 // but we do recognize the top pointer on the stack as code,
109 // then assume this was a call to non-code and treat like
110 // pc == 0, to make unwinding show the context.
111 if pc != 0 && findfunc(pc) == nil && findfunc(*(*uintptr)(unsafe.Pointer(sp))) != nil {
115 // Only push runtime.sigpanic if pc != 0.
116 // If pc == 0, probably panicked because of a
117 // call to a nil func. Not pushing that onto sp will
118 // make the trace look like a call to runtime.sigpanic instead.
119 // (Otherwise the trace will end at runtime.sigpanic and we
120 // won't get to see who faulted.)
122 if regSize > ptrSize {
124 *(*uintptr)(unsafe.Pointer(sp)) = 0
127 *(*uintptr)(unsafe.Pointer(sp)) = pc
128 c.set_rsp(uint64(sp))
130 c.set_rip(uint64(funcPC(sigpanic)))
134 if c.sigcode() == _SI_USER || flags&_SigNotify != 0 {
140 if flags&_SigKill != 0 {
144 if flags&_SigThrow == 0 {
149 _g_.m.caughtsig.set(gp)
155 if sig < uint32(len(sigtable)) {
156 print(sigtable[sig].name, "\n")
158 print("Signal ", sig, "\n")
161 print("PC=", hex(c.rip()), " m=", _g_.m.id, "\n")
162 if _g_.m.lockedg != nil && _g_.m.ncgo > 0 && gp == _g_.m.g0 {
163 print("signal arrived during cgo execution\n")
168 level, _, docrash := gotraceback()
171 tracebacktrap(uintptr(c.rip()), uintptr(c.rsp()), 0, gp)
172 if crashing > 0 && gp != _g_.m.curg && _g_.m.curg != nil && readgstatus(_g_.m.curg)&^_Gscan == _Grunning {
173 // tracebackothers on original m skipped this one; trace it now.
174 goroutineheader(_g_.m.curg)
175 traceback(^uintptr(0), ^uintptr(0), 0, gp)
176 } else if crashing == 0 {
185 if crashing < sched.mcount {
186 // There are other m's that need to dump their stacks.
187 // Relay SIGQUIT to the next m by sending it to the current process.
188 // All m's that have already received SIGQUIT have signal masks blocking
189 // receipt of any signals, so the SIGQUIT will go to an m that hasn't seen it yet.
190 // When the last m receives the SIGQUIT, it will fall through to the call to
191 // crash below. Just in case the relaying gets botched, each m involved in
192 // the relay sleeps for 5 seconds and then does the crash/exit itself.
193 // In expected operation, the last m has received the SIGQUIT and run
194 // crash/exit and the process is gone, all long before any of the
195 // 5-second sleeps have finished.
198 usleep(5 * 1000 * 1000)