git: 5524122ee3b7 - stable/13 - x86: clear %db registers in new process

[Konstantin Belousov]

The branch stable/13 has been updated by kib:

URL: https://cgit.FreeBSD.org/src/commit/?id=5524122ee3b78b3a9bba1d0a0d9b8ac080a8e6d8

commit 5524122ee3b78b3a9bba1d0a0d9b8ac080a8e6d8
Author:     Konstantin Belousov <kib at FreeBSD.org>
AuthorDate: 2021-03-30 15:40:02 +0000
Commit:     Konstantin Belousov <kib at FreeBSD.org>
CommitDate: 2021-04-06 00:47:34 +0000

    x86: clear %db registers in new process
    
    PR:     254661
    
    (cherry picked from commit 8223717ce62c1ad0becc34ce69fe2d1771f3ba05)
---
 sys/amd64/amd64/vm_machdep.c | 8 ++++++++
 sys/i386/i386/vm_machdep.c   | 8 ++++++++
 2 files changed, 16 insertions(+)

diff --git a/sys/amd64/amd64/vm_machdep.c b/sys/amd64/amd64/vm_machdep.c
index f64259decbff..98d212dc8771 100644
--- a/sys/amd64/amd64/vm_machdep.c
+++ b/sys/amd64/amd64/vm_machdep.c
@@ -229,6 +229,14 @@ cpu_fork(struct thread *td1, struct proc *p2, struct thread *td2, int flags)
 
 	copy_thread(td1, td2);
 
+	/* Reset debug registers in the new process */
+	pcb2->pcb_dr0 = 0;
+	pcb2->pcb_dr1 = 0;
+	pcb2->pcb_dr2 = 0;
+	pcb2->pcb_dr3 = 0;
+	pcb2->pcb_dr6 = 0;
+	pcb2->pcb_dr7 = 0;
+
 	/* Point mdproc and then copy over p1's contents */
 	mdp2 = &p2->p_md;
 	bcopy(&p1->p_md, mdp2, sizeof(*mdp2));
diff --git a/sys/i386/i386/vm_machdep.c b/sys/i386/i386/vm_machdep.c
index c04fb57db4b1..ed40ebe5d1c8 100644
--- a/sys/i386/i386/vm_machdep.c
+++ b/sys/i386/i386/vm_machdep.c
@@ -241,6 +241,14 @@ cpu_fork(struct thread *td1, struct proc *p2, struct thread *td2, int flags)
 
 	copy_thread(td1, td2);
 
+	/* Reset debug registers in the new process */
+	pcb2->pcb_dr0 = 0;
+	pcb2->pcb_dr1 = 0;
+	pcb2->pcb_dr2 = 0;
+	pcb2->pcb_dr3 = 0;
+	pcb2->pcb_dr6 = 0;
+	pcb2->pcb_dr7 = 0;
+
 	/* Point mdproc and then copy over td1's contents */
 	mdp2 = &p2->p_md;
 	bcopy(&p1->p_md, mdp2, sizeof(*mdp2));