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 <eddyz87@xxxxxxxxx>
---
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 882079f16291..002d1e9b2260 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);
--
2.47.1
