Simplify code that determines the number of arguments for a given function.

For amd64 this means removing db_numargs() and directly setting
narg to the correct value (instead of capping it during iteration).

On i386 rename db_numargs() to db_i386_numargs() and only call it
when we fail to get the correct number out of CTF.

discussed with an ok mpi@

2 files changed, 12 insertions, 23 deletions

diff --git a/sys/arch/amd64/amd64/db_trace.c b/sys/arch/amd64/amd64/db_trace.c
index 8760bd70d20..44a5228bbc3 100644
--- a/sys/arch/amd64/amd64/db_trace.c
+++ b/sys/arch/amd64/amd64/db_trace.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: db_trace.c,v 1.34 2017/08/14 16:32:37 mpi Exp $	*/
+/*	$OpenBSD: db_trace.c,v 1.35 2017/10/17 19:23:09 jasper Exp $	*/
 /*	$NetBSD: db_trace.c,v 1.1 2003/04/26 18:39:27 fvdl Exp $	*/
 
 /*
@@ -79,21 +79,9 @@ struct db_variable * db_eregs = db_regs + nitems(db_regs);
 #define	INTERRUPT	3
 #define	AST		4
 
-int db_numargs(struct callframe *, Elf_Sym *);
 void db_nextframe(struct callframe **, db_addr_t *, long *, int,
     int (*) (const char *, ...));
 
-int
-db_numargs(struct callframe *fp, Elf_Sym *sym)
-{
-	int args;
-
-	if ((args = db_ctf_func_numargs(sym)) != -1)
-		return args;
-
-	return 6;
-}
-
 /*
  * Figure out the next frame up in the call stack.
  * For trap(), we print the address of the faulting instruction and
@@ -243,14 +231,16 @@ db_stack_trace_print(db_expr_t addr, boolean_t have_addr, db_expr_t count,
 			narg = 0;
 		else {
 			is_trap = NONE;
-			narg = db_numargs(frame, sym);
+			narg = db_ctf_func_numargs(sym);
+			if (narg < 0 || narg > 6)
+				narg = 6;
 		}
 
 		(*pr)("%s(", name);
 
 		if (lastframe == 0 && offset == 0 && !have_addr) {
 			/* We have a breakpoint before the frame is set up */
-			for (i = 0; i < min(6, narg); i++) {
+			for (i = 0; i < narg; i++) {
 				(*pr)("%lx", *db_reg_args[i]);
 				if (--narg != 0)
 					(*pr)(",");
@@ -261,7 +251,7 @@ db_stack_trace_print(db_expr_t addr, boolean_t have_addr, db_expr_t count,
 			    &((struct callframe *)(ddb_regs.tf_rsp-8))->f_arg0;
 		} else {
 			argp = (unsigned long *)frame;
-			for (i = min(6, narg); i > 0; i--) {
+			for (i = narg; i > 0; i--) {
 				argp--;
 				(*pr)("%lx", db_get_value((db_addr_t)argp,
 				    sizeof(*argp), FALSE));
diff --git a/sys/arch/i386/i386/db_trace.c b/sys/arch/i386/i386/db_trace.c
index f65102128a2..2389c9e26df 100644
--- a/sys/arch/i386/i386/db_trace.c
+++ b/sys/arch/i386/i386/db_trace.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: db_trace.c,v 1.29 2017/08/11 20:50:15 mpi Exp $	*/
+/*	$OpenBSD: db_trace.c,v 1.30 2017/10/17 19:23:09 jasper Exp $	*/
 /*	$NetBSD: db_trace.c,v 1.18 1996/05/03 19:42:01 christos Exp $	*/
 
 /*
@@ -74,7 +74,7 @@ struct db_variable *db_eregs = db_regs + nitems(db_regs);
 #define	INTERRUPT	3
 #define	AST		4
 
-int db_numargs(struct callframe *, Elf_Sym *);
+int db_i386_numargs(struct callframe *);
 void db_nextframe(struct callframe **, db_addr_t *, int *, int,
     int (*pr)(const char *, ...));
 
@@ -82,16 +82,13 @@ void db_nextframe(struct callframe **, db_addr_t *, int *, int,
  * Figure out how many arguments were passed into the frame at "fp".
  */
 int
-db_numargs(struct callframe *fp, Elf_Sym *sym)
+db_i386_numargs(struct callframe *fp)
 {
 	int	*argp;
 	int	inst;
 	int	args;
 	extern char	etext[];
 
-	if ((args = db_ctf_func_numargs(sym)) != -1)
-		return args;
-
 	argp = (int *)db_get_value((int)&fp->f_retaddr, 4, FALSE);
 	if (argp < (int *)VM_MIN_KERNEL_ADDRESS || argp > (int *)etext) {
 		args = 5;
@@ -255,7 +252,9 @@ db_stack_trace_print(db_expr_t addr, boolean_t have_addr, db_expr_t count,
 			narg = 0;
 		else {
 			is_trap = NONE;
-			narg = db_numargs(frame, sym);
+			narg = db_ctf_func_numargs(sym);
+			if (narg < 0)
+				narg = db_i386_numargs(frame);
 		}
 
 		(*pr)("%s(", name);