Commit 53431798 authored by Masami Hiramatsu (Google)'s avatar Masami Hiramatsu (Google)
Browse files

tracing/probes: Fix tracepoint event with $arg* to fetch correct argument 

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.

Link: https://lore.kernel.org/all/168657113778.3038017.12245893750241701312.stgit@mhiramat.roam.corp.google.com/



Reviewed-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: default avatarMasami Hiramatsu (Google) <mhiramat@kernel.org>
parent a2bd0c08

kernel/trace/trace_probe.c

+8 −2
Original line number Diff line number Diff line
@@ -456,6 +456,9 @@ static int parse_btf_arg(const char *varname, struct fetch_insn *code, 


		if (name && !strcmp(name, varname)) {

			code->op = FETCH_OP_ARG;

			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);

}