Index: sys/amd64/amd64/db_trace.c
===================================================================
--- sys/amd64/amd64/db_trace.c
+++ sys/amd64/amd64/db_trace.c
@@ -188,7 +188,6 @@
 #define	TRAP_INTERRUPT	5
 
 static void db_nextframe(struct amd64_frame **, db_addr_t *, struct thread *);
-static int db_numargs(struct amd64_frame *);
 static void db_print_stack_entry(const char *, int, char **, long *, db_addr_t,
     void *);
 static void decode_syscall(int, struct thread *);
@@ -198,62 +197,12 @@
 		    int access, struct dbreg *d);
 int  amd64_clr_watch(int watchnum, struct dbreg *d);
 
-/*
- * Figure out how many arguments were passed into the frame at "fp".
- */
-static int
-db_numargs(fp)
-	struct amd64_frame *fp;
-{
-#if 1
-	return (0);	/* regparm, needs dwarf2 info */
-#else
-	long	*argp;
-	int	inst;
-	int	args;
-
-	argp = (long *)db_get_value((long)&fp->f_retaddr, 8, FALSE);
-	/*
-	 * XXX etext is wrong for LKMs.  We should attempt to interpret
-	 * the instruction at the return address in all cases.  This
-	 * may require better fault handling.
-	 */
-	if (argp < (long *)btext || argp >= (long *)etext) {
-		args = 5;
-	} else {
-		inst = db_get_value((long)argp, 4, FALSE);
-		if ((inst & 0xff) == 0x59)	/* popl %ecx */
-			args = 1;
-		else if ((inst & 0xffff) == 0xc483)	/* addl $Ibs, %esp */
-			args = ((inst >> 16) & 0xff) / 4;
-		else
-			args = 5;
-	}
-	return (args);
-#endif
-}
-
 static void
-db_print_stack_entry(name, narg, argnp, argp, callpc, frame)
-	const char *name;
-	int narg;
-	char **argnp;
-	long *argp;
-	db_addr_t callpc;
-	void *frame;
+db_print_stack_entry(const char *name, int narg, char **argnp, long *argp,
+    db_addr_t callpc, void *frame)
 {
-	db_printf("%s(", name);
-#if 0
-	while (narg) {
-		if (argnp)
-			db_printf("%s=", *argnp++);
-		db_printf("%lr", (long)db_get_value((long)argp, 8, FALSE));
-		argp++;
-		if (--narg != 0)
-			db_printf(",");
-	}
-#endif
-	db_printf(") at ");
+
+	db_printf("%s() at ", name);
 	db_printsym(callpc, DB_STGY_PROC);
 	if (frame != NULL)
 		db_printf("/frame 0x%lx", (register_t)frame);
@@ -384,8 +333,8 @@
 }
 
 static int
-db_backtrace(struct thread *td, struct trapframe *tf,
-    struct amd64_frame *frame, db_addr_t pc, int count)
+db_backtrace(struct thread *td, struct amd64_frame *frame, db_addr_t pc,
+    int count)
 {
 	struct amd64_frame *actframe;
 #define MAXNARG	16
@@ -405,41 +354,9 @@
 		sym = db_search_symbol(pc, DB_STGY_ANY, &offset);
 		db_symbol_values(sym, &name, NULL);
 
-		/*
-		 * Attempt to determine a (possibly fake) frame that gives
-		 * the caller's pc.  It may differ from `frame' if the
-		 * current function never sets up a standard frame or hasn't
-		 * set one up yet or has just discarded one.  The last two
-		 * cases can be guessed fairly reliably for code generated
-		 * by gcc.  The first case is too much trouble to handle in
-		 * general because the amount of junk on the stack depends
-		 * on the pc (the special handling of "calltrap", etc. in
-		 * db_nextframe() works because the `next' pc is special).
-		 */
 		actframe = frame;
 		if (first) {
-			if (tf != NULL) {
-				int instr;
-
-				instr = db_get_value(pc, 4, FALSE);
-				if ((instr & 0xffffffff) == 0xe5894855) {
-					/* pushq %rbp; movq %rsp, %rbp */
-					actframe = (void *)(get_rsp(tf) - 8);
-				} else if ((instr & 0xffffff) == 0xe58948) {
-					/* movq %rsp, %rbp */
-					actframe = (void *)get_rsp(tf);
-					if (tf->tf_rbp == 0) {
-						/* Fake frame better. */
-						frame = actframe;
-					}
-				} else if ((instr & 0xff) == 0xc3) {
-					/* ret */
-					actframe = (void *)(get_rsp(tf) - 8);
-				} else if (offset == 0) {
-					/* Probably an assembler symbol. */
-					actframe = (void *)(get_rsp(tf) - 8);
-				}
-			} else if (strcmp(name, "fork_trampoline") == 0) {
+			if (strcmp(name, "fork_trampoline") == 0) {
 				/*
 				 * Don't try to walk back on a stack for a
 				 * process that hasn't actually been run yet.
@@ -456,7 +373,7 @@
 		if (sym != NULL && db_sym_numargs(sym, &narg, argnames)) {
 			argnp = argnames;
 		} else {
-			narg = db_numargs(frame);
+			narg = 0;
 		}
 
 		db_print_stack_entry(name, narg, argnp, argp, pc, actframe);
@@ -495,7 +412,7 @@
 	frame = (struct amd64_frame *)rbp;
 	callpc = (db_addr_t)db_get_value((long)&frame->f_retaddr, 8, FALSE);
 	frame = frame->f_frame;
-	db_backtrace(curthread, NULL, frame, callpc, -1);
+	db_backtrace(curthread, frame, callpc, -1);
 }
 
 int
@@ -504,8 +421,8 @@
 	struct pcb *ctx;
 
 	ctx = kdb_thr_ctx(thr);
-	return (db_backtrace(thr, NULL, (struct amd64_frame *)ctx->pcb_rbp,
-		    ctx->pcb_rip, count));
+	return (db_backtrace(thr, (struct amd64_frame *)ctx->pcb_rbp,
+	    ctx->pcb_rip, count));
 }
 
 int