runtime: print error on receipt of signal on non-Go thread

It's the best we can do before Go 1.

For issue 3250; not a fix but at least less mysterious.

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/5797068

src/pkg/runtime/sys_darwin_386.s

@@ -126,13 +126,18 @@ TEXT runtime·sigaction(SB),7,$0
 //	20(FP)	context
 TEXT runtime·sigtramp(SB),7,$40
 	get_tls(CX)
+	
+	// check that m exists
+	MOVL	m(CX), BP
+	CMPL	BP, $0
+	JNE	2(PC)
+	CALL	runtime·badsignal(SB)
 
 	// save g
 	MOVL	g(CX), DI
 	MOVL	DI, 20(SP)
 
 	// g = m->gsignal
-	MOVL	m(CX), BP
 	MOVL	m_gsignal(BP), BP
 	MOVL	BP, g(CX)
 

src/pkg/runtime/sys_darwin_amd64.s

@@ -117,12 +117,17 @@ TEXT runtime·sigaction(SB),7,$0
 TEXT runtime·sigtramp(SB),7,$64
 	get_tls(BX)
 
+	// check that m exists
+	MOVQ	m(BX), BP
+	CMPQ	BP, $0
+	JNE	2(PC)
+	CALL	runtime·badsignal(SB)
+
 	// save g
 	MOVQ	g(BX), R10
 	MOVQ	R10, 48(SP)
 
 	// g = m->gsignal
-	MOVQ	m(BX), BP
 	MOVQ	m_gsignal(BP), BP
 	MOVQ	BP, g(BX)
 

src/pkg/runtime/sys_freebsd_386.s

@@ -159,12 +159,17 @@ TEXT runtime·sigaction(SB),7,$-4
 TEXT runtime·sigtramp(SB),7,$44
 	get_tls(CX)
 
+	// check that m exists
+	MOVL	m(CX), BX
+	CMPL	BX, $0
+	JNE	2(PC)
+	CALL	runtime·badsignal(SB)
+
 	// save g
 	MOVL	g(CX), DI
 	MOVL	DI, 20(SP)
 	
 	// g = m->gsignal
-	MOVL	m(CX), BX
 	MOVL	m_gsignal(BX), BX
 	MOVL	BX, g(CX)
 

src/pkg/runtime/sys_freebsd_amd64.s

@@ -135,12 +135,17 @@ TEXT runtime·sigaction(SB),7,$-8
 TEXT runtime·sigtramp(SB),7,$64
 	get_tls(BX)
 	
+	// check that m exists
+	MOVQ	m(BX), BP
+	CMPQ	BP, $0
+	JNE	2(PC)
+	CALL	runtime·badsignal(SB)
+
 	// save g
 	MOVQ	g(BX), R10
 	MOVQ	R10, 40(SP)
 	
 	// g = m->signal
-	MOVQ	m(BX), BP
 	MOVQ	m_gsignal(BP), BP
 	MOVQ	BP, g(BX)
 	

src/pkg/runtime/sys_linux_386.s

@@ -167,6 +167,12 @@ TEXT runtime·rt_sigaction(SB),7,$0
 TEXT runtime·sigtramp(SB),7,$44
 	get_tls(CX)
 
+	// check that m exists
+	MOVL	m(CX), BX
+	CMPL	BX, $0
+	JNE	2(PC)
+	CALL	runtime·badsignal(SB)
+
 	// save g
 	MOVL	g(CX), DI
 	MOVL	DI, 20(SP)

src/pkg/runtime/sys_linux_amd64.s

@@ -154,12 +154,17 @@ TEXT runtime·rt_sigaction(SB),7,$0-32
 TEXT runtime·sigtramp(SB),7,$64
 	get_tls(BX)
 
+	// check that m exists
+	MOVQ	m(BX), BP
+	CMPQ	BP, $0
+	JNE	2(PC)
+	CALL	runtime·badsignal(SB)
+
 	// save g
 	MOVQ	g(BX), R10
 	MOVQ	R10, 40(SP)
 
 	// g = m->gsignal
-	MOVQ	m(BX), BP
 	MOVQ	m_gsignal(BP), BP
 	MOVQ	BP, g(BX)
 

src/pkg/runtime/sys_netbsd_386.s

@@ -138,12 +138,17 @@ TEXT runtime·sigaction(SB),7,$-4
 TEXT runtime·sigtramp(SB),7,$44
 	get_tls(CX)
 
+	// check that m exists
+	MOVL	m(CX), BX
+	CMPL	BX, $0
+	JNE	2(PC)
+	CALL	runtime·badsignal(SB)
+
 	// save g
 	MOVL	g(CX), DI
 	MOVL	DI, 20(SP)
 	
 	// g = m->gsignal
-	MOVL	m(CX), BX
 	MOVL	m_gsignal(BX), BX
 	MOVL	BX, g(CX)
 

src/pkg/runtime/sys_netbsd_amd64.s

@@ -176,12 +176,17 @@ TEXT runtime·sigaction(SB),7,$-8
 TEXT runtime·sigtramp(SB),7,$64
 	get_tls(BX)
 	
+	// check that m exists
+	MOVQ	m(BX), BP
+	CMPQ	BP, $0
+	JNE	2(PC)
+	CALL	runtime·badsignal(SB)
+
 	// save g
 	MOVQ	g(BX), R10
 	MOVQ	R10, 40(SP)
 	
 	// g = m->signal
-	MOVQ	m(BX), BP
 	MOVQ	m_gsignal(BP), BP
 	MOVQ	BP, g(BX)
 	

src/pkg/runtime/sys_openbsd_386.s

@@ -138,12 +138,17 @@ TEXT runtime·sigaction(SB),7,$-4
 TEXT runtime·sigtramp(SB),7,$44
 	get_tls(CX)
 
+	// check that m exists
+	MOVL	m(CX), BX
+	CMPL	BX, $0
+	JNE	2(PC)
+	CALL	runtime·badsignal(SB)
+
 	// save g
 	MOVL	g(CX), DI
 	MOVL	DI, 20(SP)
 	
 	// g = m->gsignal
-	MOVL	m(CX), BX
 	MOVL	m_gsignal(BX), BX
 	MOVL	BX, g(CX)
 

src/pkg/runtime/sys_openbsd_amd64.s

@@ -176,12 +176,17 @@ TEXT runtime·sigaction(SB),7,$-8
 TEXT runtime·sigtramp(SB),7,$64
 	get_tls(BX)
 	
+	// check that m exists
+	MOVQ	m(BX), BP
+	CMPQ	BP, $0
+	JNE	2(PC)
+	CALL	runtime·badsignal(SB)
+
 	// save g
 	MOVQ	g(BX), R10
 	MOVQ	R10, 40(SP)
 	
 	// g = m->signal
-	MOVQ	m(BX), BP
 	MOVQ	m_gsignal(BP), BP
 	MOVQ	BP, g(BX)
 	

src/pkg/runtime/sys_windows_386.s

@@ -58,6 +58,26 @@ TEXT	runtime·badcallback(SB),7,$24
 	MOVL	BP, SI
 	RET
 
+TEXT	runtime·badsignal(SB),7,$24
+	// stderr
+	MOVL	$-12, 0(SP)
+	MOVL	SP, BP
+	CALL	*runtime·GetStdHandle(SB)
+	MOVL	BP, SP
+
+	MOVL	AX, 0(SP)	// handle
+	MOVL	$runtime·badsignalmsg(SB), DX // pointer
+	MOVL	DX, 4(SP)
+	MOVL	runtime·badsignallen(SB), DX // count
+	MOVL	DX, 8(SP)
+	LEAL	20(SP), DX  // written count
+	MOVL	$0, 0(DX)
+	MOVL	DX, 12(SP)
+	MOVL	$0, 16(SP) // overlapped
+	CALL	*runtime·WriteFile(SB)
+	MOVL	BP, SI
+	RET
+
 // faster get/set last error
 TEXT runtime·getlasterror(SB),7,$0
 	MOVL	0x34(FS), AX
@@ -79,7 +99,15 @@ TEXT runtime·sigtramp(SB),7,$28
 	MOVL	CX, 0(SP)
 	MOVL	context+8(FP), CX
 	MOVL	CX, 4(SP)
+
 	get_tls(CX)
+
+	// check that m exists
+	MOVL	m(CX), AX
+	CMPL	AX, $0
+	JNE	2(PC)
+	CALL	runtime·badsignal(SB)
+
 	MOVL	g(CX), CX
 	MOVL	CX, 8(SP)
 

src/pkg/runtime/sys_windows_amd64.s

@@ -82,6 +82,28 @@ TEXT runtime·badcallback(SB),7,$48
 	
 	RET
 
+TEXT runtime·badsignal(SB),7,$48
+	// stderr
+	MOVQ	$-12, CX // stderr
+	MOVQ	CX, 0(SP)
+	MOVQ	runtime·GetStdHandle(SB), AX
+	CALL	AX
+
+	MOVQ	AX, CX	// handle
+	MOVQ	CX, 0(SP)
+	MOVQ	$runtime·badsignalmsg(SB), DX // pointer
+	MOVQ	DX, 8(SP)
+	MOVL	$runtime·badsignallen(SB), R8 // count
+	MOVQ	R8, 16(SP)
+	LEAQ	40(SP), R9  // written count
+	MOVQ	$0, 0(R9)
+	MOVQ	R9, 24(SP)
+	MOVQ	$0, 32(SP)	// overlapped
+	MOVQ	runtime·WriteFile(SB), AX
+	CALL	AX
+	
+	RET
+
 // faster get/set last error
 TEXT runtime·getlasterror(SB),7,$0
 	MOVQ	0x30(GS), AX
@@ -106,7 +128,15 @@ TEXT runtime·sigtramp(SB),7,$56
 	// copy arguments for call to sighandler
 	MOVQ	CX, 0(SP)
 	MOVQ	R8, 8(SP)
+
 	get_tls(CX)
+
+	// check that m exists
+	MOVQ	m(BX), AX
+	CMPQ	AX, $0
+	JNE	2(PC)
+	CALL	runtime·badsignal(SB)
+
 	MOVQ	g(CX), CX
 	MOVQ	CX, 16(SP)
 

src/pkg/runtime/thread_darwin.c

@@ -487,3 +487,13 @@ runtime·badcallback(void)
 {
 	runtime·write(2, badcallback, sizeof badcallback - 1);
 }
+
+static int8 badsignal[] = "runtime: signal received on thread not created by Go.\n";
+
+// This runs on a foreign stack, without an m or a g.  No stack split.
+#pragma textflag 7
+void
+runtime·badsignal(void)
+{
+	runtime·write(2, badsignal, sizeof badsignal - 1);
+}

src/pkg/runtime/thread_freebsd.c

@@ -205,3 +205,13 @@ runtime·badcallback(void)
 {
 	runtime·write(2, badcallback, sizeof badcallback - 1);
 }
+
+static int8 badsignal[] = "runtime: signal received on thread not created by Go.\n";
+
+// This runs on a foreign stack, without an m or a g.  No stack split.
+#pragma textflag 7
+void
+runtime·badsignal(void)
+{
+	runtime·write(2, badsignal, sizeof badsignal - 1);
+}

src/pkg/runtime/thread_linux.c

@@ -265,3 +265,13 @@ runtime·badcallback(void)
 {
 	runtime·write(2, badcallback, sizeof badcallback - 1);
 }
+
+static int8 badsignal[] = "runtime: signal received on thread not created by Go.\n";
+
+// This runs on a foreign stack, without an m or a g.  No stack split.
+#pragma textflag 7
+void
+runtime·badsignal(void)
+{
+	runtime·write(2, badsignal, sizeof badsignal - 1);
+}

src/pkg/runtime/thread_netbsd.c

@@ -223,3 +223,13 @@ runtime·badcallback(void)
 {
 	runtime·write(2, badcallback, sizeof badcallback - 1);
 }
+
+static int8 badsignal[] = "runtime: signal received on thread not created by Go.\n";
+
+// This runs on a foreign stack, without an m or a g.  No stack split.
+#pragma textflag 7
+void
+runtime·badsignal(void)
+{
+	runtime·write(2, badsignal, sizeof badsignal - 1);
+}

src/pkg/runtime/thread_openbsd.c

@@ -223,3 +223,13 @@ runtime·badcallback(void)
 {
 	runtime·write(2, badcallback, sizeof badcallback - 1);
 }
+
+static int8 badsignal[] = "runtime: signal received on thread not created by Go.\n";
+
+// This runs on a foreign stack, without an m or a g.  No stack split.
+#pragma textflag 7
+void
+runtime·badsignal(void)
+{
+	runtime·write(2, badsignal, sizeof badsignal - 1);
+}

src/pkg/runtime/thread_plan9.c

@@ -257,3 +257,13 @@ runtime·badcallback(void)
 {
 	runtime·pwrite(2, badcallback, sizeof badcallback - 1, -1LL);
 }
+
+static int8 badsignal[] = "runtime: signal received on thread not created by Go.\n";
+
+// This runs on a foreign stack, without an m or a g.  No stack split.
+#pragma textflag 7
+void
+runtime·badsignal(void)
+{
+	runtime·pwrite(2, badsignal, sizeof badsignal - 1, -1LL);
+}

src/pkg/runtime/thread_windows.c

@@ -425,3 +425,6 @@ runtime·setprof(bool on)
 
 int8 runtime·badcallbackmsg[] = "runtime: cgo callback on thread not created by Go.\n";
 int32 runtime·badcallbacklen = sizeof runtime·badcallbackmsg - 1;
+
+int8 runtime·badsignalmsg[] = "runtime: signal received on thread not created by Go.\n";
+int32 runtime·badsignallen = sizeof runtime·badsignalmsg - 1;