runtime: log all thread stack traces during GODEBUG=crash on Linux and OS X

Normally, a panic/throw only shows the thread stack for the current thread
and all paused goroutines. Goroutines running on other threads, or other threads
running on their system stacks, are opaque. Change that when GODEBUG=crash,
by passing a SIGQUIT around to all the threads when GODEBUG=crash.
If this works out reasonably well, we might make the SIGQUIT relay part of
the standard panic/throw death, perhaps eliding idle m's.

Change-Id: If7dd354f7f3a6e326d17c254afcf4f7681af2f8b
Reviewed-on: https://go-review.googlesource.com/2811
Reviewed-by: Rick Hudson <rlh@golang.org>

src/runtime/defs_nacl_386.go

@@ -3,6 +3,7 @@ package runtime
 const (
 	// These values are referred to in the source code
 	// but really don't matter. Even so, use the standard numbers.
+	_SIGQUIT = 3
 	_SIGSEGV = 11
 	_SIGPROF = 27
 )

src/runtime/defs_nacl_amd64p32.go

@@ -3,6 +3,7 @@ package runtime
 const (
 	// These values are referred to in the source code
 	// but really don't matter. Even so, use the standard numbers.
+	_SIGQUIT = 3
 	_SIGSEGV = 11
 	_SIGPROF = 27
 )

src/runtime/defs_nacl_arm.go

@@ -3,6 +3,7 @@ package runtime
 const (
 	// These values are referred to in the source code
 	// but really don't matter. Even so, use the standard numbers.
+	_SIGQUIT = 3
 	_SIGSEGV = 11
 	_SIGPROF = 27
 )

src/runtime/defs_windows.go

@@ -41,7 +41,6 @@ const (
 	DUPLICATE_SAME_ACCESS   = C.DUPLICATE_SAME_ACCESS
 	THREAD_PRIORITY_HIGHEST = C.THREAD_PRIORITY_HIGHEST
 
-	SIGPROF          = 0 // dummy value for badsignal
 	SIGINT           = C.SIGINT
 	CTRL_C_EVENT     = C.CTRL_C_EVENT
 	CTRL_BREAK_EVENT = C.CTRL_BREAK_EVENT

src/runtime/defs_windows_386.go

@@ -15,7 +15,6 @@ const (
 	_DUPLICATE_SAME_ACCESS   = 0x2
 	_THREAD_PRIORITY_HIGHEST = 0x2
 
-	_SIGPROF          = 0 // dummy value for badsignal
 	_SIGINT           = 0x2
 	_CTRL_C_EVENT     = 0x0
 	_CTRL_BREAK_EVENT = 0x1

src/runtime/defs_windows_amd64.go

@@ -15,7 +15,6 @@ const (
 	_DUPLICATE_SAME_ACCESS   = 0x2
 	_THREAD_PRIORITY_HIGHEST = 0x2
 
-	_SIGPROF          = 0 // dummy value for badsignal
 	_SIGINT           = 0x2
 	_CTRL_C_EVENT     = 0x0
 	_CTRL_BREAK_EVENT = 0x1

src/runtime/os1_windows.go

@@ -575,6 +575,14 @@ func setBadSignalMsg() {
 	}
 }
 
+const (
+	_SIGPROF = 0 // dummy value for badsignal
+	_SIGQUIT = 0 // dummy value for sighandler
+)
+
+func raiseproc(sig int32) {
+}
+
 func crash() {
 	// TODO: This routine should do whatever is needed
 	// to make the Windows program abort/crash as it

src/runtime/os2_plan9.go

@@ -69,6 +69,6 @@ const (
 	_SIGINTDIV = 4
 	_SIGFLOAT  = 5
 	_SIGTRAP   = 6
-	// dummy value defined for badsignal
-	_SIGPROF   = 0
+	_SIGPROF   = 0 // dummy value defined for badsignal
+	_SIGQUIT   = 0 // dummy value defined for sighandler
 )

src/runtime/os3_solaris.go

@@ -418,6 +418,10 @@ func raise(sig int32) /* int32 */ {
 	sysvicall1(libc_raise, uintptr(sig))
 }
 
+func raiseproc(sig int32) /* int32 */ {
+	sysvicall1(libc_raise, uintptr(sig))
+}
+
 //go:nosplit
 func read(fd int32, buf unsafe.Pointer, nbyte int32) int32 {
 	return int32(sysvicall3(libc_read, uintptr(fd), uintptr(buf), uintptr(nbyte)))

src/runtime/os_darwin.go

@@ -34,3 +34,4 @@ func sigtramp()
 func setitimer(mode int32, new, old *itimerval)
 
 func raise(int32)
+func raiseproc(int32)

src/runtime/os_dragonfly.go

@@ -28,6 +28,7 @@ func sysctl(mib *uint32, miblen uint32, out *byte, size *uintptr, dst *byte, nds
 func getrlimit(kind int32, limit unsafe.Pointer) int32
 
 func raise(sig int32)
+func raiseproc(sig int32)
 
 //go:noescape
 func sys_umtx_sleep(addr *uint32, val, timeout int32) int32

src/runtime/os_freebsd.go

@@ -27,6 +27,7 @@ func sysctl(mib *uint32, miblen uint32, out *byte, size *uintptr, dst *byte, nds
 //go:noescape
 func getrlimit(kind int32, limit unsafe.Pointer) int32
 func raise(sig int32)
+func raiseproc(sig int32)
 
 //go:noescape
 func sys_umtx_op(addr *uint32, mode int32, val uint32, ptr2, ts *timespec) int32

src/runtime/os_linux.go

@@ -27,6 +27,7 @@ func rtsigprocmask(sig uint32, new, old *sigset, size int32)
 //go:noescape
 func getrlimit(kind int32, limit unsafe.Pointer) int32
 func raise(sig uint32)
+func raiseproc(sig uint32)
 
 //go:noescape
 func sched_getaffinity(pid, len uintptr, buf *uintptr) int32

src/runtime/os_nacl.go

@@ -49,3 +49,6 @@ func sigpanic() {
 	g.sig = _SIGSEGV
 	panicmem()
 }
+
+func raiseproc(sig int32) {
+}

src/runtime/os_netbsd.go

@@ -24,6 +24,7 @@ func sysctl(mib *uint32, miblen uint32, out *byte, size *uintptr, dst *byte, nds
 func lwp_tramp()
 
 func raise(sig int32)
+func raiseproc(sig int32)
 
 //go:noescape
 func getcontext(ctxt unsafe.Pointer)

src/runtime/os_openbsd.go

@@ -20,6 +20,7 @@ func sigprocmask(mode int32, new uint32) uint32
 func sysctl(mib *uint32, miblen uint32, out *byte, size *uintptr, dst *byte, ndst uintptr) int32
 
 func raise(sig int32)
+func raiseproc(sig int32)
 
 //go:noescape
 func tfork(param *tforkt, psize uintptr, mm *m, gg *g, fn uintptr) int32

src/runtime/signal_amd64x.go

@@ -7,7 +7,9 @@
 
 package runtime
 
-import "unsafe"
+import (
+	"unsafe"
+)
 
 func dumpregs(c *sigctxt) {
 	print("rax    ", hex(c.rax()), "\n")
@@ -33,6 +35,8 @@ func dumpregs(c *sigctxt) {
 	print("gs     ", hex(c.gs()), "\n")
 }
 
+var crashing int32
+
 func sighandler(sig uint32, info *siginfo, ctxt unsafe.Pointer, gp *g) {
 	_g_ := getg()
 	c := &sigctxt{info, ctxt}
@@ -131,7 +135,10 @@ func sighandler(sig uint32, info *siginfo, ctxt unsafe.Pointer, gp *g) {
 
 	_g_.m.throwing = 1
 	_g_.m.caughtsig = gp
+
+	if crashing == 0 {
 		startpanic()
+	}
 
 	if sig < uint32(len(sigtable)) {
 		print(sigtable[sig].name, "\n")
@@ -139,7 +146,7 @@ func sighandler(sig uint32, info *siginfo, ctxt unsafe.Pointer, gp *g) {
 		print("Signal ", sig, "\n")
 	}
 
-	print("PC=", hex(c.rip()), "\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
@@ -150,12 +157,39 @@ func sighandler(sig uint32, info *siginfo, ctxt unsafe.Pointer, gp *g) {
 	if gotraceback(&docrash) > 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 docrash {
+		// TODO(rsc): Implement raiseproc on other systems
+		// and then add to this switch.
+		switch GOOS {
+		case "darwin", "linux":
+			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()
 	}
 

src/runtime/sys_darwin_386.s

@@ -50,7 +50,12 @@ TEXT runtime·write(SB),NOSPLIT,$0
 	MOVL	AX, ret+12(FP)
 	RET
 
-TEXT runtime·raise(SB),NOSPLIT,$16
+TEXT runtime·raise(SB),NOSPLIT,$0
+	// Ideally we'd send the signal to the current thread,
+	// not the whole process, but that's too hard on OS X.
+	JMP	runtime·raiseproc(SB)
+
+TEXT runtime·raiseproc(SB),NOSPLIT,$16
 	MOVL	$20, AX // getpid
 	INT	$0x80
 	MOVL	AX, 4(SP)	// pid

src/runtime/sys_darwin_amd64.s

@@ -66,7 +66,12 @@ TEXT runtime·write(SB),NOSPLIT,$0
 	MOVL	AX, ret+24(FP)
 	RET
 
-TEXT runtime·raise(SB),NOSPLIT,$24
+TEXT runtime·raise(SB),NOSPLIT,$0
+	// Ideally we'd send the signal to the current thread,
+	// not the whole process, but that's too hard on OS X.
+	JMP	runtime·raiseproc(SB)
+
+TEXT runtime·raiseproc(SB),NOSPLIT,$24
 	MOVL	$(0x2000000+20), AX // getpid
 	SYSCALL
 	MOVQ	AX, DI	// arg 1 - pid

src/runtime/sys_linux_386.s

@@ -93,6 +93,15 @@ TEXT runtime·raise(SB),NOSPLIT,$12
 	CALL	*runtime·_vdso(SB)
 	RET
 
+TEXT runtime·raiseproc(SB),NOSPLIT,$12
+	MOVL	$20, AX	// syscall - getpid
+	CALL	*runtime·_vdso(SB)
+	MOVL	AX, BX	// arg 1 pid
+	MOVL	sig+0(FP), CX	// arg 2 signal
+	MOVL	$37, AX	// syscall - kill
+	CALL	*runtime·_vdso(SB)
+	RET
+
 TEXT runtime·setitimer(SB),NOSPLIT,$0-12
 	MOVL	$104, AX			// syscall - setitimer
 	MOVL	mode+0(FP), BX

src/runtime/sys_linux_amd64.s

@@ -91,6 +91,15 @@ TEXT runtime·raise(SB),NOSPLIT,$0
 	SYSCALL
 	RET
 
+TEXT runtime·raiseproc(SB),NOSPLIT,$0
+	MOVL	$39, AX	// syscall - getpid
+	SYSCALL
+	MOVL	AX, DI	// arg 1 pid
+	MOVL	sig+0(FP), SI	// arg 2
+	MOVL	$62, AX	// syscall - kill
+	SYSCALL
+	RET
+
 TEXT runtime·setitimer(SB),NOSPLIT,$0-24
 	MOVL	mode+0(FP), DI
 	MOVQ	new+8(FP), SI

src/runtime/sys_linux_arm.s

@@ -18,6 +18,8 @@
 #define SYS_write (SYS_BASE + 4)
 #define SYS_open (SYS_BASE + 5)
 #define SYS_close (SYS_BASE + 6)
+#define SYS_getpid (SYS_BASE + 20)
+#define SYS_kill (SYS_BASE + 37)
 #define SYS_gettimeofday (SYS_BASE + 78)
 #define SYS_clone (SYS_BASE + 120)
 #define SYS_rt_sigreturn (SYS_BASE + 173)
@@ -113,6 +115,15 @@ TEXT	runtime·raise(SB),NOSPLIT,$-4
 	SWI	$0
 	RET
 
+TEXT	runtime·raiseproc(SB),NOSPLIT,$-4
+	MOVW	$SYS_getpid, R7
+	SWI	$0
+	// arg 1 tid already in R0 from getpid
+	MOVW	sig+0(FP), R1	// arg 2 - signal
+	MOVW	$SYS_kill, R7
+	SWI	$0
+	RET
+
 TEXT runtime·mmap(SB),NOSPLIT,$0
 	MOVW	0(FP), R0
 	MOVW	4(FP), R1

src/runtime/sys_linux_ppc64x.s

@@ -18,6 +18,8 @@
 #define SYS_write		  4
 #define SYS_open		  5
 #define SYS_close		  6
+#define SYS_getpid		 20
+#define SYS_kill		 37
 #define SYS_fcntl		 55
 #define SYS_gettimeofday	 78
 #define SYS_select		 82	// always return -ENOSYS
@@ -118,6 +120,13 @@ TEXT runtime·raise(SB),NOSPLIT,$-8
 	SYSCALL	$SYS_tkill
 	RETURN
 
+TEXT runtime·raiseproc(SB),NOSPLIT,$-8
+	SYSCALL	$SYS_getpid
+	MOVW	R3, R3	// arg 1 pid
+	MOVW	sig+0(FP), R4	// arg 2
+	SYSCALL	$SYS_kill
+	RETURN
+
 TEXT runtime·setitimer(SB),NOSPLIT,$-8-24
 	MOVW	mode+0(FP), R3
 	MOVD	new+8(FP), R4