> Date: Mon, 12 Jul 2021 20:11:30 +0200
> From: Jasper Lievisse Adriaanse <[email protected]>
>
> On Sun, Jul 11, 2021 at 03:58:05PM +0200, Jasper Lievisse Adriaanse wrote:
> > Hi,
> >
> > When printing a trace from ddb, some architectures are limited by the
> > number of
> > registers which are used to pass arguments. If the number of arguments to a
> > function
> > exceeded this number, the code in db_stack_trace_print() would print that
> > many arguments
> > without any indication that one or more arguments aren't printed.
> >
> > Here's a diff that tweaks the output to make it clear there were more
> > arguments.
> > Do we want to print ',...' for each ommited argument (like this diff does)
> > or perhaps just a single ',...'?
>
> I think just printing a single instance of ',...' gets the point across.
> OK?
Actually, since we use -msave-args on amd64 the arguments are saved on
the stack. I think this means there is no limit on the number of
arguments we can print...
> Index: arch/amd64/amd64/db_trace.c
> ===================================================================
> RCS file: /cvs/src/sys/arch/amd64/amd64/db_trace.c,v
> retrieving revision 1.53
> diff -u -p -r1.53 db_trace.c
> --- arch/amd64/amd64/db_trace.c 14 May 2020 06:58:54 -0000 1.53
> +++ arch/amd64/amd64/db_trace.c 12 Jul 2021 18:08:21 -0000
> @@ -137,7 +137,7 @@ db_stack_trace_print(db_expr_t addr, int
>
> lastframe = 0;
> while (count && frame != 0) {
> - int narg;
> + int narg, extra_args = 0;
> unsigned int i;
> char * name;
> db_expr_t offset;
> @@ -165,8 +165,12 @@ db_stack_trace_print(db_expr_t addr, int
> }
>
> narg = db_ctf_func_numargs(sym);
> - if (narg < 0 || narg > 6)
> + if (narg < 0)
> narg = 6;
> + else if (narg > 6) {
> + narg = 6;
> + extra_args = 1;
> + }
>
> if (name == NULL)
> (*pr)("%lx(", callpc);
> @@ -204,6 +208,10 @@ db_stack_trace_print(db_expr_t addr, int
> if (--narg != 0)
> (*pr)(",");
> }
> +
> + if (extra_args)
> + (*pr)(",...");
> +
> (*pr)(") at ");
> db_printsym(callpc, DB_STGY_PROC, pr);
> (*pr)("\n");
> Index: arch/powerpc/ddb/db_trace.c
> ===================================================================
> RCS file: /cvs/src/sys/arch/powerpc/ddb/db_trace.c,v
> retrieving revision 1.17
> diff -u -p -r1.17 db_trace.c
> --- arch/powerpc/ddb/db_trace.c 14 May 2020 06:58:54 -0000 1.17
> +++ arch/powerpc/ddb/db_trace.c 12 Jul 2021 18:08:21 -0000
> @@ -123,7 +123,7 @@ db_stack_trace_print(db_expr_t addr, int
> Elf_Sym *sym;
> char *name;
> char c, *cp = modif;
> - int i, narg, trace_proc = 0;
> + int i, narg, trace_proc = 0, extra_args = 0;
>
> while ((c = *cp++) != 0) {
> if (c == 't')
> @@ -158,8 +158,12 @@ db_stack_trace_print(db_expr_t addr, int
> (*pr)("at 0x%lx", lr - 4);
> } else {
> narg = db_ctf_func_numargs(sym);
> - if (narg < 0 || narg > 8)
> + if (narg < 0)
> narg = 8;
> + else if (narg > 8) {
> + narg = 8;
> + extra_args = 1;
> + }
>
> (*pr)("%s(", name);
>
> @@ -172,6 +176,9 @@ db_stack_trace_print(db_expr_t addr, int
> (*pr)(",");
> }
> }
> +
> + if (extra_args)
> + (*pr)(",...");
>
> (*pr)(") at ");
> db_printsym(lr - 4, DB_STGY_PROC, pr);
>
> --
> jasper
>
>
