4 files changed, 38 insertions, 19 deletions

diff --git a/lib/libpthread/thread/thr_init.c b/lib/libpthread/thread/thr_init.c
index 35731c4..be671a1 100644
--- a/lib/libpthread/thread/thr_init.c
+++ b/lib/libpthread/thread/thr_init.c
@@ -92,7 +92,6 @@ _thread_init(void)
 	int		mib[2];
 	struct clockinfo clockinfo;
 	struct sigaction act;
-	struct sigaltstack alt;
 
 	/* Check if this function has already been called: */
 	if (_thread_initial)
@@ -281,11 +280,15 @@ _thread_init(void)
 		/* Clear the signal queue: */
 		memset(_thread_sigq, 0, sizeof(_thread_sigq));
 
-		/* Create and install an alternate signal stack: */
-		alt.ss_sp = malloc(SIGSTKSZ);	/* recommended stack size */
-		alt.ss_size = SIGSTKSZ;
-		alt.ss_flags = 0;
-		if (_thread_sys_sigaltstack(&alt, NULL) != 0)
+		/*
+		 * Create and install an alternate signal stack of
+		 * the recommended size:
+		 */
+		_thread_sigstack.ss_sp = malloc(SIGSTKSZ);
+		_thread_sigstack.ss_size = SIGSTKSZ;
+		_thread_sigstack.ss_flags = 0;
+		if ((_thread_sigstack.ss_sp == NULL) ||
+		    (_thread_sys_sigaltstack(&_thread_sigstack, NULL) != 0))
 			PANIC("Unable to install alternate signal stack");
 
 		/* Enter a loop to get the existing signal status: */
diff --git a/lib/libpthread/thread/thr_kern.c b/lib/libpthread/thread/thr_kern.c
index 4d92385..2b7b270 100644
--- a/lib/libpthread/thread/thr_kern.c
+++ b/lib/libpthread/thread/thr_kern.c
@@ -71,6 +71,7 @@ thread_run_switch_hook(pthread_t thread_out, pthread_t thread_in);
 
 /* Static variables: */
 static int	last_tick = 0;
+static int	called_from_handler = 0;
 
 /*
  * This is called when a signal handler finishes and wants to
@@ -106,20 +107,12 @@ _thread_kern_sched(ucontext_t *scp)
 
 	/* Check if this function was called from the signal handler: */
 	if (scp != NULL) {
-		/*
-		 * The signal handler should have saved the state of
-		 * the current thread.  Restore the process signal
-		 * mask.
-		 */
-		if (_thread_sys_sigprocmask(SIG_SETMASK,
-		    &_process_sigmask, NULL) != 0)
-			PANIC("Unable to restore process mask after signal");
+		called_from_handler = 1;
 		/*
 		 * We're running on the signal stack; just call the
 		 * kernel scheduler directly.
 		 */
 		DBG_MSG("Entering scheduler due to signal\n");
-		_thread_kern_scheduler();
 	} else {
 		/* Save the state of the current thread: */
 		if (_setjmp(_thread_run->ctx.jb) == 0) {
@@ -162,9 +155,9 @@ _thread_kern_sched(ucontext_t *scp)
 			}
 			return;
 		}
-		/* Switch to the thread scheduler: */
-		___longjmp(_thread_kern_sched_jb, 1);
 	}
+	/* Switch to the thread scheduler: */
+	___longjmp(_thread_kern_sched_jb, 1);
 }
 
 void
@@ -188,6 +181,26 @@ _thread_kern_scheduler(void)
 	if ((_thread_run->flags & PTHREAD_FLAGS_PRIVATE) == 0)
 		_last_user_thread = _thread_run;
 
+	if (called_from_handler != 0) {
+		called_from_handler = 0;
+
+		/*
+		 * The signal handler should have saved the state of
+		 * the current thread.  Restore the process signal
+		 * mask.
+		 */
+		if (_thread_sys_sigprocmask(SIG_SETMASK,
+		    &_process_sigmask, NULL) != 0)
+			PANIC("Unable to restore process mask after signal");
+
+		/*
+		 * Since the signal handler didn't return normally, we
+		 * have to tell the kernel to reuse the signal stack.
+		 */
+		if (_thread_sys_sigaltstack(&_thread_sigstack, NULL) != 0)
+			PANIC("Unable to restore alternate signal stack");
+	}
+
 	/* Are there pending signals for this thread? */
 	if (_thread_run->check_pending != 0) {
 		_thread_run->check_pending = 0;
diff --git a/lib/libpthread/thread/thr_private.h b/lib/libpthread/thread/thr_private.h
index e8fff12..9d6bc31 100644
--- a/lib/libpthread/thread/thr_private.h
+++ b/lib/libpthread/thread/thr_private.h
@@ -1127,6 +1127,9 @@ SCLASS	volatile int	_sigq_check_reqd
 #endif
 ;
 
+/* The signal stack. */
+SCLASS struct sigaltstack _thread_sigstack;
+
 /* Thread switch hook. */
 SCLASS pthread_switch_routine_t _sched_switch_hook
 #ifdef GLOBAL_PTHREAD_PRIVATE
@@ -1268,7 +1271,7 @@ int     _thread_sys_sigsuspend(const sigset_t *);
 int     _thread_sys_siginterrupt(int, int);
 int     _thread_sys_sigpause(int);
 int     _thread_sys_sigreturn(ucontext_t *);
-int     _thread_sys_sigaltstack(const struct sigaltstack *, struct sigstack *);
+int     _thread_sys_sigaltstack(const struct sigaltstack *, struct sigaltstack *);
 int     _thread_sys_sigstack(const struct sigstack *, struct sigstack *);
 int     _thread_sys_sigvec(int, struct sigvec *, struct sigvec *);
 void    _thread_sys_psignal(unsigned int, const char *);
diff --git a/lib/libpthread/thread/thr_sig.c b/lib/libpthread/thread/thr_sig.c
index 3bcd9c1..3ac9740 100644
--- a/lib/libpthread/thread/thr_sig.c
+++ b/lib/libpthread/thread/thr_sig.c
@@ -1066,7 +1066,7 @@ thread_sigframe_add(pthread_t thread, int sig, int has_args)
 	/*
 	 * Set up the context:
 	 */
-	stackp += sizeof(double);
+	stackp -= sizeof(double);
 	_setjmp(thread->ctx.jb);
 	SET_STACK_JB(thread->ctx.jb, stackp);
 	SET_RETURN_ADDR_JB(thread->ctx.jb, _thread_sig_wrapper);