savectx() strikes again: the saved stack pointer wasn't properly adjusted

to remove the return address. It's only the frame pointer and luck that
allowed the code to work at all.

5 files changed, 18 insertions, 31 deletions

diff --git a/sys/amd64/amd64/cpu_switch.S b/sys/amd64/amd64/cpu_switch.S
index fdaacd2..a07a559 100644
--- a/sys/amd64/amd64/cpu_switch.S
+++ b/sys/amd64/amd64/cpu_switch.S
@@ -33,7 +33,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- *	$Id: swtch.s,v 1.25 1996/01/03 21:41:29 wollman Exp $
+ *	$Id: swtch.s,v 1.26 1996/01/23 02:39:16 davidg Exp $
  */
 
 #include "npx.h"	/* for NNPX */
@@ -510,7 +510,7 @@ ENTRY(mvesp)
  * Update pcb, saving current processor state.
  */
 ENTRY(savectx)
-	/* PCB */
+	/* fetch PCB */
 	movl	4(%esp),%ecx
 
 	/* caller's return address - child won't execute this routine */
@@ -519,7 +519,8 @@ ENTRY(savectx)
 
 	movl	$1,PCB_EAX(%ecx)		/* return 1 in child */
 	movl	%ebx,PCB_EBX(%ecx)
-	movl	%esp,PCB_ESP(%ecx)
+	leal	4(%esp),%eax			/* stack minus return address */
+	movl	%eax,PCB_ESP(%ecx)
 	movl	%ebp,PCB_EBP(%ecx)
 	movl	%esi,PCB_ESI(%ecx)
 	movl	%edi,PCB_EDI(%ecx)
diff --git a/sys/amd64/amd64/swtch.s b/sys/amd64/amd64/swtch.s
index fdaacd2..a07a559 100644
--- a/sys/amd64/amd64/swtch.s
+++ b/sys/amd64/amd64/swtch.s
@@ -33,7 +33,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- *	$Id: swtch.s,v 1.25 1996/01/03 21:41:29 wollman Exp $
+ *	$Id: swtch.s,v 1.26 1996/01/23 02:39:16 davidg Exp $
  */
 
 #include "npx.h"	/* for NNPX */
@@ -510,7 +510,7 @@ ENTRY(mvesp)
  * Update pcb, saving current processor state.
  */
 ENTRY(savectx)
-	/* PCB */
+	/* fetch PCB */
 	movl	4(%esp),%ecx
 
 	/* caller's return address - child won't execute this routine */
@@ -519,7 +519,8 @@ ENTRY(savectx)
 
 	movl	$1,PCB_EAX(%ecx)		/* return 1 in child */
 	movl	%ebx,PCB_EBX(%ecx)
-	movl	%esp,PCB_ESP(%ecx)
+	leal	4(%esp),%eax			/* stack minus return address */
+	movl	%eax,PCB_ESP(%ecx)
 	movl	%ebp,PCB_EBP(%ecx)
 	movl	%esi,PCB_ESI(%ecx)
 	movl	%edi,PCB_EDI(%ecx)
diff --git a/sys/amd64/amd64/vm_machdep.c b/sys/amd64/amd64/vm_machdep.c
index a8edbbd..5f1f50f 100644
--- a/sys/amd64/amd64/vm_machdep.c
+++ b/sys/amd64/amd64/vm_machdep.c
@@ -38,7 +38,7 @@
  *
  *	from: @(#)vm_machdep.c	7.3 (Berkeley) 5/13/91
  *	Utah $Hdr: vm_machdep.c 1.16.1.1 89/06/23$
- *	$Id: vm_machdep.c,v 1.51 1996/01/19 03:57:43 dyson Exp $
+ *	$Id: vm_machdep.c,v 1.52 1996/01/23 02:39:17 davidg Exp $
  */
 
 #include "npx.h"
@@ -587,17 +587,9 @@ cpu_fork(p1, p2)
 	pmap_activate(&p2->p_vmspace->vm_pmap, &up->u_pcb);
 
 	/*
-	 *
-	 * Arrange for a non-local goto when the new process
-	 * is started, to resume here, returning nonzero from setjmp.
+	 * Return (0) in parent, (1) in child.
 	 */
-	if (savectx(&up->u_pcb)) {
-		/*
-		 * Return 1 in child.
-		 */
-		return (1);
-	}
-	return (0);
+	return (savectx(&up->u_pcb));
 }
 
 void
diff --git a/sys/i386/i386/swtch.s b/sys/i386/i386/swtch.s
index fdaacd2..a07a559 100644
--- a/sys/i386/i386/swtch.s
+++ b/sys/i386/i386/swtch.s
@@ -33,7 +33,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- *	$Id: swtch.s,v 1.25 1996/01/03 21:41:29 wollman Exp $
+ *	$Id: swtch.s,v 1.26 1996/01/23 02:39:16 davidg Exp $
  */
 
 #include "npx.h"	/* for NNPX */
@@ -510,7 +510,7 @@ ENTRY(mvesp)
  * Update pcb, saving current processor state.
  */
 ENTRY(savectx)
-	/* PCB */
+	/* fetch PCB */
 	movl	4(%esp),%ecx
 
 	/* caller's return address - child won't execute this routine */
@@ -519,7 +519,8 @@ ENTRY(savectx)
 
 	movl	$1,PCB_EAX(%ecx)		/* return 1 in child */
 	movl	%ebx,PCB_EBX(%ecx)
-	movl	%esp,PCB_ESP(%ecx)
+	leal	4(%esp),%eax			/* stack minus return address */
+	movl	%eax,PCB_ESP(%ecx)
 	movl	%ebp,PCB_EBP(%ecx)
 	movl	%esi,PCB_ESI(%ecx)
 	movl	%edi,PCB_EDI(%ecx)
diff --git a/sys/i386/i386/vm_machdep.c b/sys/i386/i386/vm_machdep.c
index a8edbbd..5f1f50f 100644
--- a/sys/i386/i386/vm_machdep.c
+++ b/sys/i386/i386/vm_machdep.c
@@ -38,7 +38,7 @@
  *
  *	from: @(#)vm_machdep.c	7.3 (Berkeley) 5/13/91
  *	Utah $Hdr: vm_machdep.c 1.16.1.1 89/06/23$
- *	$Id: vm_machdep.c,v 1.51 1996/01/19 03:57:43 dyson Exp $
+ *	$Id: vm_machdep.c,v 1.52 1996/01/23 02:39:17 davidg Exp $
  */
 
 #include "npx.h"
@@ -587,17 +587,9 @@ cpu_fork(p1, p2)
 	pmap_activate(&p2->p_vmspace->vm_pmap, &up->u_pcb);
 
 	/*
-	 *
-	 * Arrange for a non-local goto when the new process
-	 * is started, to resume here, returning nonzero from setjmp.
+	 * Return (0) in parent, (1) in child.
 	 */
-	if (savectx(&up->u_pcb)) {
-		/*
-		 * Return 1 in child.
-		 */
-		return (1);
-	}
-	return (0);
+	return (savectx(&up->u_pcb));
 }
 
 void