From 13f843c0177eeb367ac63467c538046b90785583 Mon Sep 17 00:00:00 2001 From: Eduard Zingerman Date: Wed, 11 Jun 2025 13:08:28 -0700 Subject: [PATCH] bpf: frame_insn_idx() utility function A function to return IP for a given frame in a call stack of a state. Will be used by a next patch. The `state->insn_idx = env->insn_idx;` assignment in the do_check() allows to use frame_insn_idx with env->cur_state. At the moment bpf_verifier_state->insn_idx is set when new cached state is added in is_state_visited() and accessed only in the contexts when the state is already in the cache. Hence this assignment does not change verifier behaviour. Signed-off-by: Eduard Zingerman Link: https://lore.kernel.org/r/20250611200836.4135542-3-eddyz87@gmail.com Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 75e4f6544b2ad..ebb98a78c9197 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -1964,6 +1964,14 @@ static void update_loop_entry(struct bpf_verifier_env *env, } } +/* Return IP for a given frame in a call stack */ +static u32 frame_insn_idx(struct bpf_verifier_state *st, u32 frame) +{ + return frame == st->curframe + ? st->insn_idx + : st->frame[frame + 1]->callsite; +} + static void update_branch_counts(struct bpf_verifier_env *env, struct bpf_verifier_state *st) { struct bpf_verifier_state_list *sl = NULL, *parent_sl; @@ -18790,9 +18798,7 @@ static bool states_equal(struct bpf_verifier_env *env, * and all frame states need to be equivalent */ for (i = 0; i <= old->curframe; i++) { - insn_idx = i == old->curframe - ? env->insn_idx - : old->frame[i + 1]->callsite; + insn_idx = frame_insn_idx(old, i); if (old->frame[i]->callsite != cur->frame[i]->callsite) return false; if (!func_states_equal(env, old->frame[i], cur->frame[i], insn_idx, exact)) @@ -19687,6 +19693,7 @@ static int do_check(struct bpf_verifier_env *env) } state->last_insn_idx = env->prev_insn_idx; + state->insn_idx = env->insn_idx; if (is_prune_point(env, env->insn_idx)) { err = is_state_visited(env, env->insn_idx); -- 2.47.2