Determine whether we're currently on the alternative signal stack

dynamically, by comparing the stack pointer against the altstack
base and size, so that you get the correct answer if you longjmp
out of the signal handler, as tested by regress/sys/kern/stackjmp/.
Also, fix alt stack handling on vax, where it was completely broken.

Testing and corrections by miod@, krw@, tobiasu@, pirofti@

3 files changed, 8 insertions, 16 deletions

diff --git a/sys/arch/vax/include/cpu.h b/sys/arch/vax/include/cpu.h
index d16676d7ad5..aa30873fdd4 100644
--- a/sys/arch/vax/include/cpu.h
+++ b/sys/arch/vax/include/cpu.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: cpu.h,v 1.40 2011/09/15 00:48:24 miod Exp $	*/
+/*	$OpenBSD: cpu.h,v 1.41 2012/12/02 07:03:31 guenther Exp $	*/
 /*	$NetBSD: cpu.h,v 1.41 1999/10/21 20:01:36 ragge Exp $	*/
 
 /*
@@ -123,6 +123,7 @@ extern	int	want_resched;	/* resched() was called */
  * This is used during profiling to integrate system time.
  */
 #define	PROC_PC(p)	(((struct trapframe *)((p)->p_addr->u_pcb.framep))->pc)
+#define	PROC_STACK(p)	(((struct trapframe *)((p)->p_addr->u_pcb.framep))->sp)
 
 /*
  * Give a profiling tick to the current process when the user profiling
diff --git a/sys/arch/vax/include/signal.h b/sys/arch/vax/include/signal.h
index 65f8a520838..59f306b9887 100644
--- a/sys/arch/vax/include/signal.h
+++ b/sys/arch/vax/include/signal.h
@@ -1,4 +1,4 @@
-/*      $OpenBSD: signal.h,v 1.7 2011/03/23 16:54:37 pirofti Exp $   */
+/*      $OpenBSD: signal.h,v 1.8 2012/12/02 07:03:31 guenther Exp $   */
 /*      $NetBSD: signal.h,v 1.4 1995/01/10 19:01:52 jtc Exp $   */
 
 /*
@@ -50,7 +50,7 @@ typedef int sig_atomic_t;
  * a non-standard exit is performed.
  */
 struct	sigcontext {
-	int	sc_onstack;		/* sigstack state to restore */
+	int	__sc_unused;
 	int	sc_mask;		/* signal mask to restore */
 	int	sc_sp;			/* sp to restore */
 	int	sc_fp;			/* fp to restore */
diff --git a/sys/arch/vax/vax/machdep.c b/sys/arch/vax/vax/machdep.c
index fd8ea7d88ee..8c043067dc5 100644
--- a/sys/arch/vax/vax/machdep.c
+++ b/sys/arch/vax/vax/machdep.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: machdep.c,v 1.122 2012/10/08 21:47:50 deraadt Exp $ */
+/* $OpenBSD: machdep.c,v 1.123 2012/12/02 07:03:32 guenther Exp $ */
 /* $NetBSD: machdep.c,v 1.108 2000/09/13 15:00:23 thorpej Exp $	 */
 
 /*
@@ -346,7 +346,7 @@ consinit()
  * Old sigcontext structure, still used by userland until setjmp is fixed.
  */
 struct	osigcontext {
-	int	sc_onstack;		/* sigstack state to restore */
+	int	__sc_unused;
 	int	sc_mask;		/* signal mask to restore */
 	int	sc_sp;			/* sp to restore */
 	int	sc_fp;			/* fp to restore */
@@ -394,10 +394,6 @@ sys_sigreturn(p, v, retval)
 	    (ksc.sc_ps & PSL_CM)) {
 		return (EINVAL);
 	}
-	if (ksc.sc_onstack & 01)
-		p->p_sigstk.ss_flags |= SS_ONSTACK;
-	else
-		p->p_sigstk.ss_flags &= ~SS_ONSTACK;
 	/* Restore signal mask. */
 	p->p_sigmask = ksc.sc_mask & ~sigcantmask;
 
@@ -450,13 +446,12 @@ sendsig(catcher, sig, mask, code, type, val)
 	struct	trapframe *syscf;
 	struct	sigframe *sigf, gsigf;
 	unsigned int	cursp;
-	int	onstack;
 
 	syscf = p->p_addr->u_pcb.framep;
-	onstack = p->p_sigstk.ss_flags & SS_ONSTACK;
 
 	/* Allocate space for the signal handler context. */
-	if (onstack)
+	if ((p->p_sigstk.ss_flags & SS_DISABLE) == 0 &&
+	    !sigonstack(syscf->sp) && (psp->ps_sigonstack & sigmask(sig)))
 		cursp = ((int)p->p_sigstk.ss_sp + p->p_sigstk.ss_size);
 	else
 		cursp = syscf->sp;
@@ -475,7 +470,6 @@ sendsig(catcher, sig, mask, code, type, val)
 		initsiginfo(&gsigf.sf_si, sig, code, type, val);
 	}
 
-	gsigf.sf_sc.sc_onstack = p->p_sigstk.ss_flags & SS_ONSTACK;
 	gsigf.sf_sc.sc_mask = mask;
 	gsigf.sf_sc.sc_sp = syscf->sp; 
 	gsigf.sf_sc.sc_fp = syscf->fp; 
@@ -508,9 +502,6 @@ sendsig(catcher, sig, mask, code, type, val)
 	 */
 	syscf->sp = (unsigned)sigf;
 	syscf->ap = (unsigned)sigf + offsetof(struct sigframe, sf_pc);
-
-	if (onstack)
-		p->p_sigstk.ss_flags |= SS_ONSTACK;
 }
 
 int	waittime = -1;