kernel: catch execution read fault on SG_NOEXEC segment

fault() now has an additional pc argument that is
used to detect fault on a non-executable segment.
that is, we check on read fault if the segment
has the SG_NOEXEC attribute and the program counter
is within faulting page.

1 files changed, 1 insertions, 16 deletions

diff --git a/sys/src/9/bcm/trap.c b/sys/src/9/bcm/trap.c
index 8522eacd2..5affb4070 100644
--- a/sys/src/9/bcm/trap.c
+++ b/sys/src/9/bcm/trap.c
@@ -87,8 +87,6 @@ faultarm(Ureg *ureg, uintptr va, int user, int read)
 {
 	int n, insyscall;
 	char buf[ERRMAX];
-	static int cnt, lastpid;
-	static ulong lastva;
 
 	if(up == nil) {
 		dumpregs(ureg);
@@ -96,20 +94,7 @@ faultarm(Ureg *ureg, uintptr va, int user, int read)
 	}
 	insyscall = up->insyscall;
 	up->insyscall = 1;
-	/* this is quite helpful during mmu and cache debugging */
-	if(va == lastva && up->pid == lastpid) {
-		++cnt;
-		if (cnt >= 2)
-			/* fault() isn't fixing the underlying cause */
-			panic("fault: %d consecutive faults for va %#lux",
-				cnt+1, va);
-	} else {
-		cnt = 0;
-		lastva = va;
-		lastpid = up->pid;
-	}
-
-	n = fault(va, read);
+	n = fault(va, ureg->pc, read);
 	if(n < 0){
 		if(!user){
 			dumpregs(ureg);