when flipping the code descriptors also update cs in the

tss and not only in the frame since we might be returning that way too.
add a heuristic for detecting an exec protection fault:
iff we get a read protection fault (which we normally never
get due to our segments being always readable) we assume that
it was an exec protection indeed and go to page fault
routine which will decide the rest for us (including sending
a signal should that be needed).
problem found by drahn@ and testing by many ppl.

4 files changed, 15 insertions, 11 deletions

diff --git a/sys/arch/i386/i386/pmap.c b/sys/arch/i386/i386/pmap.c
index 1fc27e278a0..341f2d72c39 100644
--- a/sys/arch/i386/i386/pmap.c
+++ b/sys/arch/i386/i386/pmap.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: pmap.c,v 1.68 2003/04/17 03:56:20 drahn Exp $	*/
+/*	$OpenBSD: pmap.c,v 1.69 2003/05/02 21:07:47 mickey Exp $	*/
 /*	$NetBSD: pmap.c,v 1.91 2000/06/02 17:46:37 thorpej Exp $	*/
 
 /*
@@ -579,17 +579,20 @@ pmap_nxstack_account(struct pmap *pmap, vaddr_t va,
 	    va < VM_MAXUSER_ADDRESS && va >= 0x40000000) {
 		struct trapframe *tf = curproc->p_md.md_regs;
 		struct vm_map *map = &curproc->p_vmspace->vm_map;
+		struct pcb *pcb = &curproc->p_addr->u_pcb;
 
 		if (npte & PG_X && !(opte & PG_X)) {
 			if (++pmap->pm_nxpages == 1 &&
 			    pmap == vm_map_pmap(map)) {
-				tf->tf_cs = GSEL(GUCODE1_SEL, SEL_UPL);
+				pcb->pcb_cs = tf->tf_cs =
+				    GSEL(GUCODE1_SEL, SEL_UPL);
 				pmap_update_pg(va);
 			}
 		} else {
 			if (!--pmap->pm_nxpages &&
 			    pmap == vm_map_pmap(map)) {
-				tf->tf_cs = GSEL(GUCODE_SEL, SEL_UPL);
+				pcb->pcb_cs = tf->tf_cs =
+				    GSEL(GUCODE_SEL, SEL_UPL);
 				pmap_update_pg(va);
 			}
 		}
diff --git a/sys/arch/i386/i386/trap.c b/sys/arch/i386/i386/trap.c
index 8827ecd6a1d..68c6f74eac5 100644
--- a/sys/arch/i386/i386/trap.c
+++ b/sys/arch/i386/i386/trap.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: trap.c,v 1.53 2003/01/16 04:15:17 art Exp $	*/
+/*	$OpenBSD: trap.c,v 1.54 2003/05/02 21:07:48 mickey Exp $	*/
 /*	$NetBSD: trap.c,v 1.95 1996/05/05 06:50:02 mycroft Exp $	*/
 
 /*-
@@ -325,9 +325,9 @@ trap(frame)
 			goto out;
 		}
 #endif
-		sv.sival_int = rcr2();
-		trapsignal(p, SIGSEGV, vftype, SEGV_MAPERR, sv);
-		goto out;
+		if (ftype == VM_PROT_READ)
+			ftype |= VM_PROT_EXECUTE;
+		goto page_fault;
 
 	case T_TSSFLT|T_USER:
 		sv.sival_int = frame.tf_eip;
@@ -411,7 +411,7 @@ trap(frame)
 			goto we_re_toast;
 #endif
 		/* FALLTHROUGH */
-
+	page_fault:
 	case T_PAGEFLT|T_USER: {	/* page fault */
 		vaddr_t va, fa;
 		struct vmspace *vm = p->p_vmspace;
diff --git a/sys/arch/i386/include/pcb.h b/sys/arch/i386/include/pcb.h
index 18d135096cc..889bdc95397 100644
--- a/sys/arch/i386/include/pcb.h
+++ b/sys/arch/i386/include/pcb.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: pcb.h,v 1.7 2001/03/24 18:11:48 millert Exp $	*/
+/*	$OpenBSD: pcb.h,v 1.8 2003/05/02 21:07:50 mickey Exp $	*/
 /*	$NetBSD: pcb.h,v 1.21 1996/01/08 13:51:42 mycroft Exp $	*/
 
 /*-
@@ -61,6 +61,7 @@ struct pcb {
 #define	pcb_cr3	pcb_tss.tss_cr3
 #define	pcb_esp	pcb_tss.tss_esp
 #define	pcb_ebp	pcb_tss.tss_ebp
+#define	pcb_cs	pcb_tss.tss_cs
 #define	pcb_fs	pcb_tss.tss_fs
 #define	pcb_gs	pcb_tss.tss_gs
 #define	pcb_ldt_sel	pcb_tss.tss_ldt
diff --git a/sys/arch/i386/include/tss.h b/sys/arch/i386/include/tss.h
index 2ca42328a0d..5d47b1160f7 100644
--- a/sys/arch/i386/include/tss.h
+++ b/sys/arch/i386/include/tss.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: tss.h,v 1.4 2000/08/05 22:07:33 niklas Exp $	*/
+/*	$OpenBSD: tss.h,v 1.5 2003/05/02 21:07:50 mickey Exp $	*/
 /*	$NetBSD: tss.h,v 1.6 1995/10/11 04:20:28 mycroft Exp $	*/
 
 /*-
@@ -66,7 +66,7 @@ struct i386tss {
 	int	__tss_esi; 
 	int	__tss_edi; 
 	int	__tss_es;
-	int	__tss_cs;
+	int	tss_cs;
 	int	__tss_ss;
 	int	__tss_ds;
 	int	tss_fs;		/* saved segment register */