3 files changed, 32 insertions, 14 deletions

diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
index b3a36b0cfc81..1883a4a9f16a 100644
--- a/include/linux/kprobes.h
+++ b/include/linux/kprobes.h
@@ -266,7 +266,7 @@ extern void kprobes_inc_nmissed_count(struct kprobe *p);
 extern bool arch_within_kprobe_blacklist(unsigned long addr);
 extern int arch_populate_kprobe_blacklist(void);
 extern bool arch_kprobe_on_func_entry(unsigned long offset);
-extern bool kprobe_on_func_entry(kprobe_opcode_t *addr, const char *sym, unsigned long offset);
+extern int kprobe_on_func_entry(kprobe_opcode_t *addr, const char *sym, unsigned long offset);
 
 extern bool within_kprobe_blacklist(unsigned long addr);
 extern int kprobe_add_ksym_blacklist(unsigned long entry);
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index f7fb5d135930..1a5bc321e0a5 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -1954,29 +1954,45 @@ bool __weak arch_kprobe_on_func_entry(unsigned long offset)
 	return !offset;
 }
 
-bool kprobe_on_func_entry(kprobe_opcode_t *addr, const char *sym, unsigned long offset)
+/**
+ * kprobe_on_func_entry() -- check whether given address is function entry
+ * @addr: Target address
+ * @sym:  Target symbol name
+ * @offset: The offset from the symbol or the address
+ *
+ * This checks whether the given @addr+@offset or @sym+@offset is on the
+ * function entry address or not.
+ * This returns 0 if it is the function entry, or -EINVAL if it is not.
+ * And also it returns -ENOENT if it fails the symbol or address lookup.
+ * Caller must pass @addr or @sym (either one must be NULL), or this
+ * returns -EINVAL.
+ */
+int kprobe_on_func_entry(kprobe_opcode_t *addr, const char *sym, unsigned long offset)
 {
 	kprobe_opcode_t *kp_addr = _kprobe_addr(addr, sym, offset);
 
 	if (IS_ERR(kp_addr))
-		return false;
+		return PTR_ERR(kp_addr);
 
-	if (!kallsyms_lookup_size_offset((unsigned long)kp_addr, NULL, &offset) ||
-						!arch_kprobe_on_func_entry(offset))
-		return false;
+	if (!kallsyms_lookup_size_offset((unsigned long)kp_addr, NULL, &offset))
+		return -ENOENT;
 
-	return true;
+	if (!arch_kprobe_on_func_entry(offset))
+		return -EINVAL;
+
+	return 0;
 }
 
 int register_kretprobe(struct kretprobe *rp)
 {
-	int ret = 0;
+	int ret;
 	struct kretprobe_instance *inst;
 	int i;
 	void *addr;
 
-	if (!kprobe_on_func_entry(rp->kp.addr, rp->kp.symbol_name, rp->kp.offset))
-		return -EINVAL;
+	ret = kprobe_on_func_entry(rp->kp.addr, rp->kp.symbol_name, rp->kp.offset);
+	if (ret)
+		return ret;
 
 	if (kretprobe_blacklist_size) {
 		addr = kprobe_addr(&rp->kp);
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index e6fba1798771..56c7fbff7bd7 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -221,9 +221,9 @@ bool trace_kprobe_on_func_entry(struct trace_event_call *call)
 {
 	struct trace_kprobe *tk = trace_kprobe_primary_from_call(call);
 
-	return tk ? kprobe_on_func_entry(tk->rp.kp.addr,
+	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) : false;
+			tk->rp.kp.addr ? 0 : tk->rp.kp.offset) == 0) : false;
 }
 
 bool trace_kprobe_error_injectable(struct trace_event_call *call)
@@ -828,9 +828,11 @@ static int trace_kprobe_create(int argc, const char *argv[])
 		}
 		if (is_return)
 			flags |= TPARG_FL_RETURN;
-		if (kprobe_on_func_entry(NULL, symbol, offset))
+		ret = kprobe_on_func_entry(NULL, symbol, offset);
+		if (ret == 0)
 			flags |= TPARG_FL_FENTRY;
-		if (offset && is_return && !(flags & TPARG_FL_FENTRY)) {
+		/* Defer the ENOENT case until register kprobe */
+		if (ret == -EINVAL && is_return) {
 			trace_probe_log_err(0, BAD_RETPROBE);
 			goto parse_error;
 		}