[RFC PATCH 1/4] trace: Simplify kprobe overridable function check

[Yafang Shao]

Simplify the logic for checking overridable kprobe functions by removing
redundant code.

No functional change.

Signed-off-by: Yafang Shao <laoar.shao@xxxxxxxxx>
---
 kernel/trace/bpf_trace.c    | 13 ++++++---
 kernel/trace/trace_kprobe.c | 40 +++++----------------------
 kernel/trace/trace_probe.h  | 54 ++++++++++++++++++++++++++-----------
 3 files changed, 54 insertions(+), 53 deletions(-)

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 0b040a417442..c901ace836cb 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -1929,10 +1929,15 @@ int perf_event_attach_bpf_prog(struct perf_event *event,
 	 * Kprobe override only works if they are on the function entry,
 	 * and only if they are on the opt-in list.
 	 */
-	if (prog->kprobe_override &&
-	    (!trace_kprobe_on_func_entry(event->tp_event) ||
-	     !trace_kprobe_error_injectable(event->tp_event)))
-		return -EINVAL;
+	if (prog->kprobe_override) {
+		struct trace_kprobe *tp = trace_kprobe_primary_from_call(event->tp_event);
+
+		if (!tp)
+			return -EINVAL;
+		if (!trace_kprobe_on_func_entry(tp) ||
+		    !trace_kprobe_error_injectable(tp))
+			return -EINVAL;
+	}
 
 	mutex_lock(&bpf_event_mutex);
 
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index a5dbb72528e0..768702674a5c 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -53,17 +53,6 @@ static struct dyn_event_operations trace_kprobe_ops = {
 	.match = trace_kprobe_match,
 };
 
-/*
- * Kprobe event core functions
- */
-struct trace_kprobe {
-	struct dyn_event	devent;
-	struct kretprobe	rp;	/* Use rp.kp for kprobe use */
-	unsigned long __percpu *nhit;
-	const char		*symbol;	/* symbol name */
-	struct trace_probe	tp;
-};
-
 static bool is_trace_kprobe(struct dyn_event *ev)
 {
 	return ev->ops == &trace_kprobe_ops;
@@ -212,33 +201,16 @@ unsigned long trace_kprobe_address(struct trace_kprobe *tk)
 	return addr;
 }
 
-static nokprobe_inline struct trace_kprobe *
-trace_kprobe_primary_from_call(struct trace_event_call *call)
-{
-	struct trace_probe *tp;
-
-	tp = trace_probe_primary_from_call(call);
-	if (WARN_ON_ONCE(!tp))
-		return NULL;
-
-	return container_of(tp, struct trace_kprobe, tp);
-}
-
-bool trace_kprobe_on_func_entry(struct trace_event_call *call)
+bool trace_kprobe_on_func_entry(struct trace_kprobe *tp)
 {
-	struct trace_kprobe *tk = trace_kprobe_primary_from_call(call);
-
-	return tk ? (kprobe_on_func_entry(tk->rp.kp.addr,
-			tk->rp.kp.addr ? NULL : tk->rp.kp.symbol_name,
-			tk->rp.kp.addr ? 0 : tk->rp.kp.offset) == 0) : false;
+	return !kprobe_on_func_entry(tp->rp.kp.addr,
+			tp->rp.kp.addr ? NULL : tp->rp.kp.symbol_name,
+			tp->rp.kp.addr ? 0 : tp->rp.kp.offset);
 }
 
-bool trace_kprobe_error_injectable(struct trace_event_call *call)
+bool trace_kprobe_error_injectable(struct trace_kprobe *tp)
 {
-	struct trace_kprobe *tk = trace_kprobe_primary_from_call(call);
-
-	return tk ? within_error_injection_list(trace_kprobe_address(tk)) :
-	       false;
+	return within_error_injection_list(trace_kprobe_address(tp));
 }
 
 static int register_kprobe_event(struct trace_kprobe *tk);
diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
index 9fc56c937130..958eb78a9068 100644
--- a/kernel/trace/trace_probe.h
+++ b/kernel/trace/trace_probe.h
@@ -30,6 +30,7 @@
 
 #include "trace.h"
 #include "trace_output.h"
+#include "trace_dynevent.h"
 
 #define MAX_TRACE_ARGS		128
 #define MAX_ARGSTR_LEN		63
@@ -210,21 +211,6 @@ DECLARE_BASIC_PRINT_TYPE_FUNC(symbol);
 #define ASSIGN_FETCH_TYPE_END {}
 #define MAX_ARRAY_LEN	64
 
-#ifdef CONFIG_KPROBE_EVENTS
-bool trace_kprobe_on_func_entry(struct trace_event_call *call);
-bool trace_kprobe_error_injectable(struct trace_event_call *call);
-#else
-static inline bool trace_kprobe_on_func_entry(struct trace_event_call *call)
-{
-	return false;
-}
-
-static inline bool trace_kprobe_error_injectable(struct trace_event_call *call)
-{
-	return false;
-}
-#endif /* CONFIG_KPROBE_EVENTS */
-
 struct probe_arg {
 	struct fetch_insn	*code;
 	bool			dynamic;/* Dynamic array (string) is used */
@@ -271,6 +257,32 @@ struct event_file_link {
 	struct list_head		list;
 };
 
+/*
+ * Kprobe event core functions
+ */
+struct trace_kprobe {
+	struct dyn_event	devent;
+	struct kretprobe	rp;	/* Use rp.kp for kprobe use */
+	unsigned long __percpu	*nhit;
+	const char		*symbol;	/* symbol name */
+	struct trace_probe	tp;
+};
+
+#ifdef CONFIG_KPROBE_EVENTS
+bool trace_kprobe_on_func_entry(struct trace_kprobe *tp);
+bool trace_kprobe_error_injectable(struct trace_kprobe *tp);
+#else
+static inline bool trace_kprobe_on_func_entry(struct trace_kprobe *tp)
+{
+	return false;
+}
+
+static inline bool trace_kprobe_error_injectable(struct trace_kprobe *tp)
+{
+	return false;
+}
+#endif /* CONFIG_KPROBE_EVENTS */
+
 static inline unsigned int trace_probe_load_flag(struct trace_probe *tp)
 {
 	return smp_load_acquire(&tp->event->flags);
@@ -329,6 +341,18 @@ trace_probe_primary_from_call(struct trace_event_call *call)
 	return list_first_entry_or_null(&tpe->probes, struct trace_probe, list);
 }
 
+static nokprobe_inline struct trace_kprobe *
+trace_kprobe_primary_from_call(struct trace_event_call *call)
+{
+	struct trace_probe *tp;
+
+	tp = trace_probe_primary_from_call(call);
+	if (WARN_ON_ONCE(!tp))
+		return NULL;
+
+	return container_of(tp, struct trace_kprobe, tp);
+}
+
 static inline struct list_head *trace_probe_probe_list(struct trace_probe *tp)
 {
 	return &tp->event->probes;
-- 
2.47.3