diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h index 85afb6744ce251..9b75b39f83d78a 100644 --- a/include/linux/bpf_verifier.h +++ b/include/linux/bpf_verifier.h @@ -196,6 +196,7 @@ struct bpf_verifier_state { struct bpf_verifier_state_list { struct bpf_verifier_state state; struct bpf_verifier_state_list *next; + int miss_cnt, hit_cnt; }; /* Possible states for alu_state member. */ @@ -268,6 +269,7 @@ struct bpf_verifier_env { bool strict_alignment; /* perform strict pointer alignment checks */ struct bpf_verifier_state *cur_state; /* current verifier state */ struct bpf_verifier_state_list **explored_states; /* search pruning optimization */ + struct bpf_verifier_state_list *free_list; struct bpf_map *used_maps[MAX_USED_MAPS]; /* array of map's used by eBPF program */ u32 used_map_cnt; /* number of used maps */ u32 id_gen; /* used to generate unique reg IDs */ diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 2dbecc621d0606..87e187e83d4e9d 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -6107,12 +6107,14 @@ static int propagate_liveness(struct bpf_verifier_env *env, static int is_state_visited(struct bpf_verifier_env *env, int insn_idx) { struct bpf_verifier_state_list *new_sl; - struct bpf_verifier_state_list *sl; + struct bpf_verifier_state_list *sl, **pprev; struct bpf_verifier_state *cur = env->cur_state, *new; int i, j, err, states_cnt = 0; cur->last_insn_idx = env->prev_insn_idx; - sl = env->explored_states[insn_idx]; + pprev = &env->explored_states[insn_idx]; + sl = *pprev; + if (!sl) /* this 'insn_idx' instruction wasn't marked, so we will not * be doing state search here @@ -6123,6 +6125,7 @@ static int is_state_visited(struct bpf_verifier_env *env, int insn_idx) while (sl != STATE_LIST_MARK) { if (states_equal(env, &sl->state, cur)) { + sl->hit_cnt++; /* reached equivalent register/stack state, * prune the search. * Registers read by the continuation are read by us. @@ -6138,8 +6141,35 @@ static int is_state_visited(struct bpf_verifier_env *env, int insn_idx) return err; return 1; } - sl = sl->next; states_cnt++; + sl->miss_cnt++; + /* heuristic to determine whether this state is beneficial + * to keep checking from state equivalence point of view. + * Higher numbers increase max_states_per_insn and verification time, + * but do not meaningfully decrease insn_processed. + */ + if (sl->miss_cnt > sl->hit_cnt * 3 + 3) { + /* the state is unlikely to be useful. Remove it to + * speed up verification + */ + *pprev = sl->next; + if (sl->state.frame[0]->regs[0].live & REG_LIVE_DONE) { + free_verifier_state(&sl->state, false); + kfree(sl); + env->peak_states--; + } else { + /* cannot free this state, since parentage chain may + * walk it later. Add it for free_list instead to + * be freed at the end of verification + */ + sl->next = env->free_list; + env->free_list = sl; + } + sl = *pprev; + continue; + } + pprev = &sl->next; + sl = *pprev; } if (env->max_states_per_insn < states_cnt) @@ -7456,6 +7486,14 @@ static void free_states(struct bpf_verifier_env *env) struct bpf_verifier_state_list *sl, *sln; int i; + sl = env->free_list; + while (sl) { + sln = sl->next; + free_verifier_state(&sl->state, false); + kfree(sl); + sl = sln; + } + if (!env->explored_states) return;