__tfork() needs to set the stack address of the new thread in the kernel,

so that it can't get a signal while still running on the parent thread's
stack.  Also, pass in sizeof(struct __tfork) to provide forward compat
when more members are added.  This is an ABI change, so switch syscall
numbers and bump lib majors this time.

ok deraadt@ matthew@

1 files changed, 11 insertions, 7 deletions

diff --git a/sys/arch/sparc/sparc/vm_machdep.c b/sys/arch/sparc/sparc/vm_machdep.c
index 80b24f37955..8f28e16bd3f 100644
--- a/sys/arch/sparc/sparc/vm_machdep.c
+++ b/sys/arch/sparc/sparc/vm_machdep.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: vm_machdep.c,v 1.54 2011/04/07 15:30:16 miod Exp $	*/
+/*	$OpenBSD: vm_machdep.c,v 1.55 2012/06/21 00:56:59 guenther Exp $	*/
 /*	$NetBSD: vm_machdep.c,v 1.30 1997/03/10 23:55:40 pk Exp $ */
 
 /*
@@ -407,12 +407,6 @@ cpu_fork(p1, p2, stack, stacksize, func, arg)
 	/* Copy parent's trapframe */
 	*tf2 = *(struct trapframe *)((int)opcb + USPACE - sizeof(*tf2));
 
-	/*
-	 * If specified, give the child a different stack.
-	 */
-	if (stack != NULL)
-		tf2->tf_out[6] = (u_int)stack + stacksize;
-
 	/* Duplicate efforts of syscall(), but slightly differently */
 	if (tf2->tf_global[1] & SYSCALL_G2RFLAG) {
 		/* jmp %g2 (or %g7, deprecated) on success */
@@ -439,6 +433,16 @@ cpu_fork(p1, p2, stack, stacksize, func, arg)
 	rp->rw_local[0] = (int)func;		/* Function to call */
 	rp->rw_local[1] = (int)arg;		/* and its argument */
 
+	/*
+	 * If specified, give the child a different stack, with space
+	 * reserved for the frame, and zero the frame pointer.
+	 */
+	if (stack != NULL) {
+		tf2->tf_out[6] = (u_int)stack + stacksize
+		    - sizeof(struct frame);
+		rp->rw_in[6] = 0;
+	}
+
 	npcb->pcb_pc = (int)proc_trampoline - 8;
 	npcb->pcb_sp = (int)rp;
 	npcb->pcb_psr &= ~PSR_CWP;	/* Run in window #0 */