Fix entering KDB with dtrace-enabled kernel.

Reviewed by:	markj, jhb
Differential Revision:	https://reviews.freebsd.org/D24018

2 files changed, 9 insertions, 4 deletions

diff --git a/sys/cddl/dev/dtrace/riscv/dtrace_subr.c b/sys/cddl/dev/dtrace/riscv/dtrace_subr.c
index 68d98db30c83..ccc6b77090ab 100644
--- a/sys/cddl/dev/dtrace/riscv/dtrace_subr.c
+++ b/sys/cddl/dev/dtrace/riscv/dtrace_subr.c
@@ -255,6 +255,8 @@ dtrace_invop_start(struct trapframe *frame)
 	int invop;
 
 	invop = dtrace_invop(frame->tf_sepc, frame, frame->tf_sepc);
+	if (invop == 0)
+		return (-1);
 
 	if (match_opcode(invop, (MATCH_SD | RS2_RA | RS1_SP),
 	    (MASK_SD | RS2_MASK | RS1_MASK))) {
@@ -292,6 +294,10 @@ dtrace_invop_start(struct trapframe *frame)
 		return (0);
 	}
 
+#ifdef INVARIANTS
+	panic("Instruction %x doesn't match any opcode.", invop);
+#endif
+
 	return (-1);
 }
 
diff --git a/sys/riscv/riscv/trap.c b/sys/riscv/riscv/trap.c
index e1d8bb76e2df..9448043224fe 100644
--- a/sys/riscv/riscv/trap.c
+++ b/sys/riscv/riscv/trap.c
@@ -274,10 +274,9 @@ do_trap_supervisor(struct trapframe *frame)
 		break;
 	case EXCP_BREAKPOINT:
 #ifdef KDTRACE_HOOKS
-		if (dtrace_invop_jump_addr != 0) {
-			dtrace_invop_jump_addr(frame);
-			break;
-		}
+		if (dtrace_invop_jump_addr != NULL &&
+		    dtrace_invop_jump_addr(frame) == 0)
+				break;
 #endif
 #ifdef KDB
 		kdb_trap(exception, 0, frame);