tracing/probes: Use struct_size() instead of defining custom macros

Remove SIZEOF_TRACE_KPROBE() and SIZEOF_TRACE_UPROBE() and use
struct_size() as that's what it is made for. No need to have custom
macros. Especially since struct_size() has some extra memory checks for
correctness.

Link: https://lkml.kernel.org/r/20210817035027.795000217@goodmis.orgAcked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

kernel/trace/trace_kprobe.c

@@ -80,10 +80,6 @@ static struct trace_kprobe *to_trace_kprobe(struct dyn_event *ev)
 	for_each_dyn_event(dpos)		\
 		if (is_trace_kprobe(dpos) && (pos = to_trace_kprobe(dpos)))
 
-#define SIZEOF_TRACE_KPROBE(n)				\
-	(offsetof(struct trace_kprobe, tp.args) +	\
-	(sizeof(struct probe_arg) * (n)))
-
 static nokprobe_inline bool trace_kprobe_is_return(struct trace_kprobe *tk)
 {
 	return tk->rp.handler != NULL;
@@ -265,7 +261,7 @@ static struct trace_kprobe *alloc_trace_kprobe(const char *group,
 	struct trace_kprobe *tk;
 	int ret = -ENOMEM;
 
-	tk = kzalloc(SIZEOF_TRACE_KPROBE(nargs), GFP_KERNEL);
+	tk = kzalloc(struct_size(tk, tp.args, nargs), GFP_KERNEL);
 	if (!tk)
 		return ERR_PTR(ret);
 

kernel/trace/trace_uprobe.c

@@ -83,10 +83,6 @@ static struct trace_uprobe *to_trace_uprobe(struct dyn_event *ev)
 	for_each_dyn_event(dpos)		\
 		if (is_trace_uprobe(dpos) && (pos = to_trace_uprobe(dpos)))
 
-#define SIZEOF_TRACE_UPROBE(n)				\
-	(offsetof(struct trace_uprobe, tp.args) +	\
-	(sizeof(struct probe_arg) * (n)))
-
 static int register_uprobe_event(struct trace_uprobe *tu);
 static int unregister_uprobe_event(struct trace_uprobe *tu);
 
@@ -340,7 +336,7 @@ alloc_trace_uprobe(const char *group, const char *event, int nargs, bool is_ret)
 	struct trace_uprobe *tu;
 	int ret;
 
-	tu = kzalloc(SIZEOF_TRACE_UPROBE(nargs), GFP_KERNEL);
+	tu = kzalloc(struct_size(tu, tp.args, nargs), GFP_KERNEL);
 	if (!tu)
 		return ERR_PTR(-ENOMEM);