From 75354c7e52dc0f482ed3b77840e339ca9b478f51 Mon Sep 17 00:00:00 2001
From: cognet <cognet@FreeBSD.org>
Date: Sat, 20 Nov 2004 16:52:10 +0000
Subject: [PATCH] Implement enough to be able to enter and leave DDB.

---
 sys/arm/arm/undefined.c      | 25 +++++++++++++++++++++++--
 sys/arm/include/cpufunc.h    |  1 +
 sys/arm/include/db_machdep.h | 22 +++++++++++++++++++---
 3 files changed, 43 insertions(+), 5 deletions(-)

diff --git a/sys/arm/arm/undefined.c b/sys/arm/arm/undefined.c
index 6a62e9cc767..0c8ea4188a3 100644
--- a/sys/arm/arm/undefined.c
+++ b/sys/arm/arm/undefined.c
@@ -60,6 +60,9 @@ __FBSDID("$FreeBSD$");
 #include <sys/types.h>
 #include <sys/lock.h>
 #include <sys/mutex.h>
+#ifdef KDB
+#include <sys/kdb.h>
+#endif
 #ifdef FAST_FPE
 #include <sys/acct.h>
 #endif
@@ -188,6 +191,7 @@ undefinedinstruction(trapframe_t *frame)
 		enable_interrupts(I32_bit);
 
 	frame->tf_pc -= INSN_SIZE;
+	atomic_add_int(&cnt.v_trap, 1);
 
 	fault_pc = frame->tf_pc;
 
@@ -251,13 +255,30 @@ undefinedinstruction(trapframe_t *frame)
 			       fault_code) == 0)
 		    break;
 
-	if (uh == NULL) {
+	if (uh == NULL && (fault_code & FAULT_USER)) {
 		/* Fault has not been handled */
 		trapsignal(td, SIGILL, 0);
 	}
 
-	if ((fault_code & FAULT_USER) == 0)
+	if ((fault_code & FAULT_USER) == 0) {
+		if (fault_instruction == KERNEL_BREAKPOINT) {
+#ifdef KDB
+		kdb_trap(0, 0, frame);
+#else
+		printf("No debugger in kernel.\n");
+#endif
+		frame->tf_pc += 4;
 		return;
+		} else {
+#ifdef KDB
+			printf("Undefined instruction in kernel.\n");
+			kdb_trap(0, 0, frame);
+#else
+			panic("Undefined instruction in kernel.\n");
+#endif
+		}
+		
+	}		
 
 #ifdef FAST_FPE
 	/* Optimised exit code */
diff --git a/sys/arm/include/cpufunc.h b/sys/arm/include/cpufunc.h
index a558b393d2f..d1b5786180f 100644
--- a/sys/arm/include/cpufunc.h
+++ b/sys/arm/include/cpufunc.h
@@ -53,6 +53,7 @@
 static __inline void
 breakpoint(void)
 {
+	__asm(".word      0xe7ffffff");
 }
 
 struct cpu_functions {
diff --git a/sys/arm/include/db_machdep.h b/sys/arm/include/db_machdep.h
index e0b255d5207..f40daa537a0 100644
--- a/sys/arm/include/db_machdep.h
+++ b/sys/arm/include/db_machdep.h
@@ -47,7 +47,7 @@ typedef int		db_expr_t;
 #define	BKPT_SET(inst)	(BKPT_INST)
 
 #define	BKPT_SKIP do {							\
-	kdb_frame->tf_pc -= BKPT_SIZE; \
+	kdb_frame->tf_pc += BKPT_SIZE; \
 } while (0)
 
 #define	db_clear_single_step(regs)
@@ -56,9 +56,25 @@ typedef int		db_expr_t;
 #define	IS_BREAKPOINT_TRAP(type, code)	(type == T_BREAKPOINT)
 #define	IS_WATCHPOINT_TRAP(type, code)	(0)
 
+
 #define	inst_trap_return(ins)	(0)
-#define	inst_return(ins)	(0)
-#define	inst_call(ins)		(0)
+/* ldmxx reg, {..., pc}
+					    01800000  stack mode
+					    000f0000  register
+					    0000ffff  register list */
+/* mov pc, reg
+					    0000000f  register */
+#define	inst_return(ins)	(((ins) & 0x0e108000) == 0x08108000 || \
+				 ((ins) & 0x0ff0fff0) == 0x01a0f000)
+/* bl ...
+					    00ffffff  offset>>2 */
+#define	inst_call(ins)		(((ins) & 0x0f000000) == 0x0b000000)
+/* b ...
+					    00ffffff  offset>>2 */
+/* ldr pc, [pc, reg, lsl #2]
+					    0000000f  register */
+
+
 #define	inst_load(ins)		(0)
 #define	inst_store(ins)		(0)
 
-- 
2.45.2