runtime: preparation for non-Go threads running Go code

* Handle p==nil in signalstack by setting SS_DISABLE flag.
* Make minit only allocate a signal g if there's not one already.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/7323072

src/pkg/runtime/os_darwin.h

@@ -5,6 +5,7 @@
 #define SIG_DFL ((void*)0)
 #define SIG_IGN ((void*)1)
 #define SIGHUP 1
+#define SS_DISABLE 4
 
 int32	runtime·bsdthread_create(void*, M*, G*, void(*)(void));
 int32	runtime·bsdthread_register(void);

src/pkg/runtime/os_freebsd.h

 #define SIG_DFL ((void*)0)
 #define SIG_IGN ((void*)1)
 #define SIGHUP 1
+#define SS_DISABLE 4
 
 int32	runtime·thr_new(ThrParam*, int32);
 void	runtime·sighandler(int32 sig, Siginfo *info, void *context, G *gp);

src/pkg/runtime/os_linux.h

@@ -5,6 +5,7 @@
 #define SIG_DFL ((void*)0)
 #define SIG_IGN ((void*)1)
 #define SIGHUP 1
+#define SS_DISABLE 2
 
 // Linux-specific system calls
 int32	runtime·futex(uint32*, int32, uint32, Timespec*, uint32*, uint32);

src/pkg/runtime/os_netbsd.h

@@ -5,6 +5,7 @@
 #define SIG_DFL ((void*)0)
 #define SIG_IGN ((void*)1)
 #define SIGHUP 1
+#define SS_DISABLE 4
 
 #define SIG_BLOCK 1
 #define SIG_UNBLOCK 2

src/pkg/runtime/os_openbsd.h

@@ -5,6 +5,7 @@
 #define SIG_DFL ((void*)0)
 #define SIG_IGN ((void*)1)
 #define SIGHUP 1
+#define SS_DISABLE 4
 
 #define SIG_BLOCK 1
 #define SIG_UNBLOCK 2

src/pkg/runtime/signal_darwin_386.c

@@ -125,6 +125,8 @@ runtime·signalstack(byte *p, int32 n)
 	st.ss_sp = p;
 	st.ss_size = n;
 	st.ss_flags = 0;
+	if(p == nil)
+		st.ss_flags = SS_DISABLE;
 	runtime·sigaltstack(&st, nil);
 }
 

src/pkg/runtime/signal_darwin_amd64.c

@@ -135,6 +135,8 @@ runtime·signalstack(byte *p, int32 n)
 	st.ss_sp = p;
 	st.ss_size = n;
 	st.ss_flags = 0;
+	if(p == nil)
+		st.ss_flags = SS_DISABLE;
 	runtime·sigaltstack(&st, nil);
 }
 

src/pkg/runtime/signal_freebsd_386.c

@@ -120,6 +120,8 @@ runtime·signalstack(byte *p, int32 n)
 	st.ss_sp = (int8*)p;
 	st.ss_size = n;
 	st.ss_flags = 0;
+	if(p == nil)
+		st.ss_flags = SS_DISABLE;
 	runtime·sigaltstack(&st, nil);
 }
 

src/pkg/runtime/signal_freebsd_amd64.c

@@ -128,6 +128,8 @@ runtime·signalstack(byte *p, int32 n)
 	st.ss_sp = (int8*)p;
 	st.ss_size = n;
 	st.ss_flags = 0;
+	if(p == nil)
+		st.ss_flags = SS_DISABLE;
 	runtime·sigaltstack(&st, nil);
 }
 

src/pkg/runtime/signal_freebsd_arm.c

@@ -143,6 +143,8 @@ runtime·signalstack(byte *p, int32 n)
 	st.ss_sp = (uint8*)p;
 	st.ss_size = n;
 	st.ss_flags = 0;
+	if(p == nil)
+		st.ss_flags = SS_DISABLE;
 	runtime·sigaltstack(&st, nil);
 }
 

src/pkg/runtime/signal_linux_386.c

@@ -116,6 +116,8 @@ runtime·signalstack(byte *p, int32 n)
 	st.ss_sp = p;
 	st.ss_size = n;
 	st.ss_flags = 0;
+	if(p == nil)
+		st.ss_flags = SS_DISABLE;
 	runtime·sigaltstack(&st, nil);
 }
 

src/pkg/runtime/signal_linux_amd64.c

@@ -126,6 +126,8 @@ runtime·signalstack(byte *p, int32 n)
 	st.ss_sp = p;
 	st.ss_size = n;
 	st.ss_flags = 0;
+	if(p == nil)
+		st.ss_flags = SS_DISABLE;
 	runtime·sigaltstack(&st, nil);
 }
 

src/pkg/runtime/signal_linux_arm.c

@@ -132,6 +132,8 @@ runtime·signalstack(byte *p, int32 n)
 	st.ss_sp = p;
 	st.ss_size = n;
 	st.ss_flags = 0;
+	if(p == nil)
+		st.ss_flags = SS_DISABLE;
 	runtime·sigaltstack(&st, nil);
 }
 

src/pkg/runtime/signal_netbsd_386.c

@@ -120,6 +120,8 @@ runtime·signalstack(byte *p, int32 n)
 	st.ss_sp = p;
 	st.ss_size = n;
 	st.ss_flags = 0;
+	if(p == nil)
+		st.ss_flags = SS_DISABLE;
 	runtime·sigaltstack(&st, nil);
 }
 

src/pkg/runtime/signal_netbsd_amd64.c

@@ -127,6 +127,8 @@ runtime·signalstack(byte *p, int32 n)
 	st.ss_sp = p;
 	st.ss_size = n;
 	st.ss_flags = 0;
+	if(p == nil)
+		st.ss_flags = SS_DISABLE;
 	runtime·sigaltstack(&st, nil);
 }
 

src/pkg/runtime/signal_netbsd_arm.c

@@ -149,6 +149,8 @@ runtime·signalstack(byte *p, int32 n)
 	st.ss_sp = (uint8*)p;
 	st.ss_size = n;
 	st.ss_flags = 0;
+	if(p == nil)
+		st.ss_flags = SS_DISABLE;
 	runtime·sigaltstack(&st, nil);
 }
 

src/pkg/runtime/signal_openbsd_386.c

@@ -116,6 +116,8 @@ runtime·signalstack(byte *p, int32 n)
 	st.ss_sp = p;
 	st.ss_size = n;
 	st.ss_flags = 0;
+	if(p == nil)
+		st.ss_flags = SS_DISABLE;
 	runtime·sigaltstack(&st, nil);
 }
 

src/pkg/runtime/signal_openbsd_amd64.c

@@ -125,6 +125,8 @@ runtime·signalstack(byte *p, int32 n)
 	st.ss_sp = p;
 	st.ss_size = n;
 	st.ss_flags = 0;
+	if(p == nil)
+		st.ss_flags = SS_DISABLE;
 	runtime·sigaltstack(&st, nil);
 }
 

src/pkg/runtime/thread_darwin.c

@@ -113,7 +113,8 @@ void
 runtime·minit(void)
 {
 	// Initialize signal handling.
-	m->gsignal = runtime·malg(32*1024);	// OS X wants >=8K, Linux >=2K
+	if(m->gsignal == nil)
+		m->gsignal = runtime·malg(32*1024);	// OS X wants >=8K, Linux >=2K
 	runtime·signalstack((byte*)m->gsignal->stackguard - StackGuard, 32*1024);
 
 	runtime·sigprocmask(SIG_SETMASK, &sigset_none, nil);
@@ -438,10 +439,11 @@ runtime·sigpanic(void)
 	runtime·panicstring(runtime·sigtab[g->sig].name);
 }
 
-// TODO(rsc): place holder to fix build.
+#pragma textflag 7
 void
 runtime·osyield(void)
 {
+	runtime·usleep(1);
 }
 
 uintptr

src/pkg/runtime/thread_linux.c

@@ -175,7 +175,8 @@ void
 runtime·minit(void)
 {
 	// Initialize signal handling.
-	m->gsignal = runtime·malg(32*1024);	// OS X wants >=8K, Linux >=2K
+	if(m->gsignal == nil)
+		m->gsignal = runtime·malg(32*1024);	// OS X wants >=8K, Linux >=2K
 	runtime·signalstack((byte*)m->gsignal->stackguard - StackGuard, 32*1024);
 	runtime·rtsigprocmask(SIG_SETMASK, &sigset_none, nil, sizeof(Sigset));
 }

src/pkg/runtime/thread_netbsd.c

@@ -193,7 +193,8 @@ runtime·minit(void)
 	m->procid = runtime·lwp_self();
 
 	// Initialize signal handling
-	m->gsignal = runtime·malg(32*1024);
+	if(m->gsignal == nil)
+		m->gsignal = runtime·malg(32*1024);
 	runtime·signalstack((byte*)m->gsignal->stackguard - StackGuard, 32*1024);
 	runtime·sigprocmask(SIG_SETMASK, &sigset_none, nil);
 }

src/pkg/runtime/thread_openbsd.c

@@ -170,7 +170,8 @@ void
 runtime·minit(void)
 {
 	// Initialize signal handling
-	m->gsignal = runtime·malg(32*1024);
+	if(m->gsignal == nil)
+		m->gsignal = runtime·malg(32*1024);
 	runtime·signalstack((byte*)m->gsignal->stackguard - StackGuard, 32*1024);
 	runtime·sigprocmask(SIG_SETMASK, sigset_none);
 }