pc/pc64: keep shadow copy of DR7 in Mach and use that to check whether we need to reset DR7 in procsave(); remove superfluous reset of DR7 in mmurelease()

1 files changed, 6 insertions, 2 deletions

diff --git a/sys/src/9/pc64/main.c b/sys/src/9/pc64/main.c
index ea920fe56..24bb0d073 100644
--- a/sys/src/9/pc64/main.c
+++ b/sys/src/9/pc64/main.c
@@ -798,8 +798,10 @@ procrestore(Proc *p)
 {
 	uvlong t;
 	
-	if(p->dr[7] != 0)
+	if(p->dr[7] != 0){
+		m->dr7 = p->dr[7];
 		putdr(p->dr);
+	}
 
 	if(p->kp)
 		return;
@@ -814,8 +816,10 @@ procsave(Proc *p)
 {
 	uvlong t;
 	
-	if(p->dr[7] != 0)
+	if(m->dr7 != 0){
+		m->dr7 = 0;
 		putdr7(0);
+	}
 
 	cycles(&t);
 	p->kentry -= t;