On Mon, 12 Jun 2023 20:58:57 +0900
"Masami Hiramatsu (Google)" <mhiramat@xxxxxxxxxx> wrote:
> From: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
>
> To hide the first dummy 'data' argument on the tracepoint probe events,
> the BTF argument array was modified (skip the first argument for tracepoint),
> but the '$arg*' meta argument parser missed that.
>
> Fix to increment the argument index if it is tracepoint probe. And decrement
> the index when searching the type of the argument.
I'm curious. What if we want a variable that points to that data argument? ;-)
Probably just add a new type I guess.
Anyway,
Reviewed-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
-- Steve
>
> Signed-off-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
> ---
> kernel/trace/trace_probe.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
> index 473e1c43bc57..643aa3a51d5a 100644
> --- a/kernel/trace/trace_probe.c
> +++ b/kernel/trace/trace_probe.c
> @@ -456,7 +456,10 @@ static int parse_btf_arg(const char *varname, struct fetch_insn *code,
>
> if (name && !strcmp(name, varname)) {
> code->op = FETCH_OP_ARG;
> - code->param = i;
> + if (ctx->flags & TPARG_FL_TPOINT)
> + code->param = i + 1;
> + else
> + code->param = i;
> return 0;
> }
> }
> @@ -470,8 +473,11 @@ static const struct fetch_type *parse_btf_arg_type(int arg_idx,
> struct btf *btf = traceprobe_get_btf();
> const char *typestr = NULL;
>
> - if (btf && ctx->params)
> + if (btf && ctx->params) {
> + if (ctx->flags & TPARG_FL_TPOINT)
> + arg_idx--;
> typestr = type_from_btf_id(btf, ctx->params[arg_idx].type);
> + }
>
> return find_fetch_type(typestr, ctx->flags);
> }
