x86: add x86_clear_dbregs() helper

Move the code from exec_setregs() to reset debug registers state on exec,
to the x86_clear_dbregs() helper

Reviewed by:	jhb
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D29687

1 files changed, 29 insertions, 21 deletions

diff --git a/sys/i386/i386/machdep.c b/sys/i386/i386/machdep.c
index a9749d331f89..5fec2e448c53 100644
--- a/sys/i386/i386/machdep.c
+++ b/sys/i386/i386/machdep.c
@@ -1122,6 +1122,34 @@ setup_priv_lcall_gate(struct proc *p)
 #endif
 
 /*
+ * Reset the hardware debug registers if they were in use.
+ * They won't have any meaning for the newly exec'd process.
+ */
+void
+x86_clear_dbregs(struct pcb *pcb)
+{
+        if ((pcb->pcb_flags & PCB_DBREGS) == 0)
+		return;
+
+	pcb->pcb_dr0 = 0;
+	pcb->pcb_dr1 = 0;
+	pcb->pcb_dr2 = 0;
+	pcb->pcb_dr3 = 0;
+	pcb->pcb_dr6 = 0;
+	pcb->pcb_dr7 = 0;
+
+	if (pcb == curpcb) {
+		/*
+		 * Clear the debug registers on the running CPU,
+		 * otherwise they will end up affecting the next
+		 * process we switch to.
+		 */
+		reset_dbregs();
+	}
+	pcb->pcb_flags &= ~PCB_DBREGS;
+}
+
+/*
  * Reset registers to default values on exec.
  */
 void
@@ -1174,27 +1202,7 @@ exec_setregs(struct thread *td, struct image_params *imgp, uintptr_t stack)
 	/* PS_STRINGS value for BSD/OS binaries.  It is 0 for non-BSD/OS. */
 	regs->tf_ebx = (register_t)imgp->ps_strings;
 
-        /*
-         * Reset the hardware debug registers if they were in use.
-         * They won't have any meaning for the newly exec'd process.  
-         */
-        if (pcb->pcb_flags & PCB_DBREGS) {
-                pcb->pcb_dr0 = 0;
-                pcb->pcb_dr1 = 0;
-                pcb->pcb_dr2 = 0;
-                pcb->pcb_dr3 = 0;
-                pcb->pcb_dr6 = 0;
-                pcb->pcb_dr7 = 0;
-                if (pcb == curpcb) {
-		        /*
-			 * Clear the debug registers on the running
-			 * CPU, otherwise they will end up affecting
-			 * the next process we switch to.
-			 */
-		        reset_dbregs();
-                }
-		pcb->pcb_flags &= ~PCB_DBREGS;
-        }
+	x86_clear_dbregs(pcb);
 
 	pcb->pcb_initial_npxcw = __INITIAL_NPXCW__;