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

22 files changed, 41 insertions, 5 deletions

diff --git a/src/pkg/runtime/os_darwin.h b/src/pkg/runtime/os_darwin.h
index 83386fa94f..5fcb717cbb 100644
--- a/src/pkg/runtime/os_darwin.h
+++ b/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);
diff --git a/src/pkg/runtime/os_freebsd.h b/src/pkg/runtime/os_freebsd.h
index cb01e39e0a..a37ad7cd87 100644
--- a/src/pkg/runtime/os_freebsd.h
+++ b/src/pkg/runtime/os_freebsd.h
@@ -1,6 +1,7 @@
 #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);
diff --git a/src/pkg/runtime/os_linux.h b/src/pkg/runtime/os_linux.h
index 5ae5d24feb..a23fe0f735 100644
--- a/src/pkg/runtime/os_linux.h
+++ b/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);
diff --git a/src/pkg/runtime/os_netbsd.h b/src/pkg/runtime/os_netbsd.h
index 13a6279270..19d72fd254 100644
--- a/src/pkg/runtime/os_netbsd.h
+++ b/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
diff --git a/src/pkg/runtime/os_openbsd.h b/src/pkg/runtime/os_openbsd.h
index 2c6f3c4e90..a599aad053 100644
--- a/src/pkg/runtime/os_openbsd.h
+++ b/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
diff --git a/src/pkg/runtime/signal_darwin_386.c b/src/pkg/runtime/signal_darwin_386.c
index deb16d7a60..132ca931b6 100644
--- a/src/pkg/runtime/signal_darwin_386.c
+++ b/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);
 }
 
diff --git a/src/pkg/runtime/signal_darwin_amd64.c b/src/pkg/runtime/signal_darwin_amd64.c
index 33dc9a6be5..4b7256bf43 100644
--- a/src/pkg/runtime/signal_darwin_amd64.c
+++ b/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);
 }
 
diff --git a/src/pkg/runtime/signal_freebsd_386.c b/src/pkg/runtime/signal_freebsd_386.c
index f9c8f91223..254e5e2772 100644
--- a/src/pkg/runtime/signal_freebsd_386.c
+++ b/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);
 }
 
diff --git a/src/pkg/runtime/signal_freebsd_amd64.c b/src/pkg/runtime/signal_freebsd_amd64.c
index 475e69c1df..7dbf36075b 100644
--- a/src/pkg/runtime/signal_freebsd_amd64.c
+++ b/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);
 }
 
diff --git a/src/pkg/runtime/signal_freebsd_arm.c b/src/pkg/runtime/signal_freebsd_arm.c
index 5b8ad5f173..2a0e9ac913 100644
--- a/src/pkg/runtime/signal_freebsd_arm.c
+++ b/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);
 }
 
diff --git a/src/pkg/runtime/signal_linux_386.c b/src/pkg/runtime/signal_linux_386.c
index 1fdb03f572..9b45ec3bd2 100644
--- a/src/pkg/runtime/signal_linux_386.c
+++ b/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);
 }
 
diff --git a/src/pkg/runtime/signal_linux_amd64.c b/src/pkg/runtime/signal_linux_amd64.c
index 30b12fa1be..c4e39a6ab0 100644
--- a/src/pkg/runtime/signal_linux_amd64.c
+++ b/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);
 }
 
diff --git a/src/pkg/runtime/signal_linux_arm.c b/src/pkg/runtime/signal_linux_arm.c
index 577ac29bfa..b5a137c369 100644
--- a/src/pkg/runtime/signal_linux_arm.c
+++ b/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);
 }
 
diff --git a/src/pkg/runtime/signal_netbsd_386.c b/src/pkg/runtime/signal_netbsd_386.c
index f788f12f55..08744c4251 100644
--- a/src/pkg/runtime/signal_netbsd_386.c
+++ b/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);
 }
 
diff --git a/src/pkg/runtime/signal_netbsd_amd64.c b/src/pkg/runtime/signal_netbsd_amd64.c
index 5bdc143ad0..46afb682ba 100644
--- a/src/pkg/runtime/signal_netbsd_amd64.c
+++ b/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);
 }
 
diff --git a/src/pkg/runtime/signal_netbsd_arm.c b/src/pkg/runtime/signal_netbsd_arm.c
index 5dfea5ca1c..97f62687bd 100644
--- a/src/pkg/runtime/signal_netbsd_arm.c
+++ b/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);
 }
 
diff --git a/src/pkg/runtime/signal_openbsd_386.c b/src/pkg/runtime/signal_openbsd_386.c
index e1537fed82..516797c8d2 100644
--- a/src/pkg/runtime/signal_openbsd_386.c
+++ b/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);
 }
 
diff --git a/src/pkg/runtime/signal_openbsd_amd64.c b/src/pkg/runtime/signal_openbsd_amd64.c
index a82d5163c6..0d0db770b5 100644
--- a/src/pkg/runtime/signal_openbsd_amd64.c
+++ b/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);
 }
 
diff --git a/src/pkg/runtime/thread_darwin.c b/src/pkg/runtime/thread_darwin.c
index df1adf63e9..83c638067d 100644
--- a/src/pkg/runtime/thread_darwin.c
+++ b/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
diff --git a/src/pkg/runtime/thread_linux.c b/src/pkg/runtime/thread_linux.c
index 1a7eb7240c..fdd40c223e 100644
--- a/src/pkg/runtime/thread_linux.c
+++ b/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));
 }
diff --git a/src/pkg/runtime/thread_netbsd.c b/src/pkg/runtime/thread_netbsd.c
index 21fbc588a9..bbe7df6e98 100644
--- a/src/pkg/runtime/thread_netbsd.c
+++ b/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);
 }
diff --git a/src/pkg/runtime/thread_openbsd.c b/src/pkg/runtime/thread_openbsd.c
index 2900f370b7..ce8043f016 100644
--- a/src/pkg/runtime/thread_openbsd.c
+++ b/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);
 }