From: Masami Hiramatsu (Google) <mhiramat@kernel.org>

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.

Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
  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);
  }