bpf: extract same_callsites() as utility function

Extract same_callsites() from clean_live_states() as a utility function.
This function would be used by the next patch in the set.
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20231024000917.12153-3-eddyz87@gmail.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

kernel/bpf/verifier.c

@@ -1830,6 +1830,20 @@ static struct bpf_verifier_state_list **explored_state(struct bpf_verifier_env *
 	return &env->explored_states[(idx ^ state->callsite) % state_htab_size(env)];
 }
 
+static bool same_callsites(struct bpf_verifier_state *a, struct bpf_verifier_state *b)
+{
+	int fr;
+
+	if (a->curframe != b->curframe)
+		return false;
+
+	for (fr = a->curframe; fr >= 0; fr--)
+		if (a->frame[fr]->callsite != b->frame[fr]->callsite)
+			return false;
+
+	return true;
+}
+
 static void update_branch_counts(struct bpf_verifier_env *env, struct bpf_verifier_state *st)
 {
 	while (st) {
@@ -15909,18 +15923,14 @@ static void clean_live_states(struct bpf_verifier_env *env, int insn,
 			      struct bpf_verifier_state *cur)
 {
 	struct bpf_verifier_state_list *sl;
-	int i;
 
 	sl = *explored_state(env, insn);
 	while (sl) {
 		if (sl->state.branches)
 			goto next;
 		if (sl->state.insn_idx != insn ||
-		    sl->state.curframe != cur->curframe)
+		    !same_callsites(&sl->state, cur))
 			goto next;
-		for (i = 0; i <= cur->curframe; i++)
-			if (sl->state.frame[i]->callsite != cur->frame[i]->callsite)
-				goto next;
 		clean_verifier_state(env, &sl->state);
 next:
 		sl = sl->next;