Commit 9a2a0d79 authored by Eduard Zingerman's avatar Eduard Zingerman Committed by Alexei Starovoitov
Browse files

bpf: starting_state parameter for __mark_chain_precision() 



Allow `mark_chain_precision()` to run from an arbitrary starting state
by replacing direct references to `env->cur_state` with a parameter.

Signed-off-by: default avatarEduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20250611200836.4135542-4-eddyz87@gmail.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 13f843c0

kernel/bpf/verifier.c

+13 −11
Original line number Diff line number Diff line
@@ -4677,12 +4677,13 @@ static void mark_all_scalars_imprecise(struct bpf_verifier_env *env, struct bpf_ 
 * mark_all_scalars_imprecise() to hopefully get more permissive and generic

 * finalized states which help in short circuiting more future states.

 */

static int __mark_chain_precision(struct bpf_verifier_env *env, int regno)

static int __mark_chain_precision(struct bpf_verifier_env *env,

				  struct bpf_verifier_state *starting_state, int regno)

{

	struct bpf_verifier_state *st = starting_state;

	struct backtrack_state *bt = &env->bt;

	struct bpf_verifier_state *st = env->cur_state;

	int first_idx = st->first_insn_idx;

	int last_idx = env->insn_idx;

	int last_idx = starting_state->insn_idx;

	int subseq_idx = -1;

	struct bpf_func_state *func;

	struct bpf_reg_state *reg;
@@ -4693,7 +4694,7 @@ static int __mark_chain_precision(struct bpf_verifier_env *env, int regno) 
		return 0;









	/* set frame number from which we are starting to backtrack */









	bt_init(bt, env->cur_state->curframe);









	bt_init(bt, starting_state->curframe);

















	/* Do sanity checks against current state of register and/or stack









	 * slot, but don't set precise flag in current state, as precision








@@ -4757,7 +4758,7 @@ static int __mark_chain_precision(struct bpf_verifier_env *env, int regno)







				err = backtrack_insn(env, i, subseq_idx, hist, bt);









			}









			if (err == -ENOTSUPP) {









				mark_all_scalars_precise(env, env->cur_state);









				mark_all_scalars_precise(env, starting_state);









				bt_reset(bt);









				return 0;









			} else if (err) {








@@ -4845,7 +4846,7 @@ static int __mark_chain_precision(struct bpf_verifier_env *env, int regno)







	 * fallback to marking all precise









	 */









	if (!bt_empty(bt)) {









		mark_all_scalars_precise(env, env->cur_state);









		mark_all_scalars_precise(env, starting_state);









		bt_reset(bt);









	}
















@@ -4854,15 +4855,16 @@ static int __mark_chain_precision(struct bpf_verifier_env *env, int regno)















int mark_chain_precision(struct bpf_verifier_env *env, int regno)









{









	return __mark_chain_precision(env, regno);









	return __mark_chain_precision(env, env->cur_state, regno);









}

















/* mark_chain_precision_batch() assumes that env->bt is set in the caller to









 * desired reg and stack masks across all relevant frames









 */









static int mark_chain_precision_batch(struct bpf_verifier_env *env)









static int mark_chain_precision_batch(struct bpf_verifier_env *env,









				      struct bpf_verifier_state *starting_state)









{









	return __mark_chain_precision(env, -1);









	return __mark_chain_precision(env, starting_state, -1);









}

















static bool is_spillable_regtype(enum bpf_reg_type type)








@@ -9515,7 +9517,7 @@ static int get_constant_map_key(struct bpf_verifier_env *env,







	 * to prevent pruning on it.









	 */









	bt_set_frame_slot(&env->bt, key->frameno, spi);









	err = mark_chain_precision_batch(env);









	err = mark_chain_precision_batch(env, env->cur_state);









	if (err < 0)









		return err;
















@@ -18939,7 +18941,7 @@ static int propagate_precision(struct bpf_verifier_env *env,







			verbose(env, "\n");









	}

















	err = mark_chain_precision_batch(env);









	err = mark_chain_precision_batch(env, env->cur_state);









	if (err < 0)









		return err;