Commit 23b37d61 authored by Eduard Zingerman's avatar Eduard Zingerman Committed by Alexei Starovoitov
Browse files

bpf: set 'changed' status if propagate_precision() did any updates 



Add an out parameter to `propagate_precision()` to record whether any
new precision bits were set during its execution.

Signed-off-by: default avatarEduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20250611200836.4135542-5-eddyz87@gmail.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 9a2a0d79

kernel/bpf/verifier.c

+23 −12
Original line number Diff line number Diff line
@@ -4678,7 +4678,9 @@ static void mark_all_scalars_imprecise(struct bpf_verifier_env *env, struct bpf_ 
 * finalized states which help in short circuiting more future states.

 */

static int __mark_chain_precision(struct bpf_verifier_env *env,

				  struct bpf_verifier_state *starting_state, int regno)

				  struct bpf_verifier_state *starting_state,

				  int regno,

				  bool *changed)

{

	struct bpf_verifier_state *st = starting_state;

	struct backtrack_state *bt = &env->bt;
@@ -4686,13 +4688,14 @@ static int __mark_chain_precision(struct bpf_verifier_env *env, 
	int last_idx = starting_state->insn_idx;

	int subseq_idx = -1;

	struct bpf_func_state *func;

	bool tmp, skip_first = true;

	struct bpf_reg_state *reg;

	bool skip_first = true;

	int i, fr, err;









	if (!env->bpf_capable)









		return 0;

















	changed = changed ?: &tmp;









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









	bt_init(bt, starting_state->curframe);
















@@ -4738,8 +4741,10 @@ static int __mark_chain_precision(struct bpf_verifier_env *env,







				for_each_set_bit(i, mask, 32) {









					reg = &st->frame[0]->regs[i];









					bt_clear_reg(bt, i);









					if (reg->type == SCALAR_VALUE)









					if (reg->type == SCALAR_VALUE) {









						reg->precise = true;









						*changed = true;









					}









				}









				return 0;









			}








@@ -4798,10 +4803,12 @@ static int __mark_chain_precision(struct bpf_verifier_env *env,







					bt_clear_frame_reg(bt, fr, i);









					continue;









				}









				if (reg->precise)









				if (reg->precise) {









					bt_clear_frame_reg(bt, fr, i);









				else









				} else {









					reg->precise = true;









					*changed = true;









				}









			}

















			bitmap_from_u64(mask, bt_frame_stack_mask(bt, fr));








@@ -4816,10 +4823,12 @@ static int __mark_chain_precision(struct bpf_verifier_env *env,







					continue;









				}









				reg = &func->stack[i].spilled_ptr;









				if (reg->precise)









				if (reg->precise) {









					bt_clear_frame_slot(bt, fr, i);









				else









				} else {









					reg->precise = true;









					*changed = true;









				}









			}









			if (env->log.level & BPF_LOG_LEVEL2) {









				fmt_reg_mask(env->tmp_str_buf, TMP_STR_BUF_LEN,








@@ -4855,7 +4864,7 @@ static int __mark_chain_precision(struct bpf_verifier_env *env,















int mark_chain_precision(struct bpf_verifier_env *env, int regno)









{









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









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









}

















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








@@ -4864,7 +4873,7 @@ int mark_chain_precision(struct bpf_verifier_env *env, int regno)







static int mark_chain_precision_batch(struct bpf_verifier_env *env,









				      struct bpf_verifier_state *starting_state)









{









	return __mark_chain_precision(env, starting_state, -1);









	return __mark_chain_precision(env, starting_state, -1, NULL);









}

















static bool is_spillable_regtype(enum bpf_reg_type type)








@@ -18893,7 +18902,9 @@ static int propagate_liveness(struct bpf_verifier_env *env,







 * propagate them into the current state









 */









static int propagate_precision(struct bpf_verifier_env *env,









			       const struct bpf_verifier_state *old)









			       const struct bpf_verifier_state *old,









			       struct bpf_verifier_state *cur,









			       bool *changed)









{









	struct bpf_reg_state *state_reg;









	struct bpf_func_state *state;








@@ -18941,7 +18952,7 @@ static int propagate_precision(struct bpf_verifier_env *env,







			verbose(env, "\n");









	}

















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









	err = __mark_chain_precision(env, cur, -1, changed);









	if (err < 0)









		return err;
















@@ -19264,7 +19275,7 @@ static int is_state_visited(struct bpf_verifier_env *env, int insn_idx)







			 */









			if (is_jmp_point(env, env->insn_idx))









				err = err ? : push_jmp_history(env, cur, 0, 0);









			err = err ? : propagate_precision(env, &sl->state);









			err = err ? : propagate_precision(env, &sl->state, cur, NULL);









			if (err)









				return err;









			return 1;