bpf: Consolidate locks and reference state in verifier state

Currently, state for RCU read locks and preemption is in
bpf_verifier_state, while locks and pointer reference state remains in
bpf_func_state. There is no particular reason to keep the latter in
bpf_func_state. Additionally, it is copied into a new frame's state and
copied back to the caller frame's state everytime the verifier processes
a pseudo call instruction. This is a bit wasteful, given this state is
global for a given verification state / path.

Move all resource and reference related state in bpf_verifier_state
structure in this patch, in preparation for introducing new reference
state types in the future.

Since we switch print_verifier_state and friends to print using vstate,
we now need to explicitly pass in the verifier state from the caller
along with the bpf_func_state, so modify the prototype and callers to do
so. To ensure func state matches the verifier state when we're printing
data, take in frame number instead of bpf_func_state pointer instead and
avoid inconsistencies induced by the caller.

Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20241204030400.208005-2-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 11 insertions, 9 deletions

diff --git a/kernel/bpf/log.c b/kernel/bpf/log.c
index 4a858fdb6476..2d28ce926053 100644
--- a/kernel/bpf/log.c
+++ b/kernel/bpf/log.c
@@ -753,9 +753,10 @@ static void print_reg_state(struct bpf_verifier_env *env,
 	verbose(env, ")");
 }
 
-void print_verifier_state(struct bpf_verifier_env *env, const struct bpf_func_state *state,
-			  bool print_all)
+void print_verifier_state(struct bpf_verifier_env *env, const struct bpf_verifier_state *vstate,
+			  u32 frameno, bool print_all)
 {
+	const struct bpf_func_state *state = vstate->frame[frameno];
 	const struct bpf_reg_state *reg;
 	int i;
 
@@ -843,11 +844,11 @@ void print_verifier_state(struct bpf_verifier_env *env, const struct bpf_func_st
 			break;
 		}
 	}
-	if (state->acquired_refs && state->refs[0].id) {
-		verbose(env, " refs=%d", state->refs[0].id);
-		for (i = 1; i < state->acquired_refs; i++)
-			if (state->refs[i].id)
-				verbose(env, ",%d", state->refs[i].id);
+	if (vstate->acquired_refs && vstate->refs[0].id) {
+		verbose(env, " refs=%d", vstate->refs[0].id);
+		for (i = 1; i < vstate->acquired_refs; i++)
+			if (vstate->refs[i].id)
+				verbose(env, ",%d", vstate->refs[i].id);
 	}
 	if (state->in_callback_fn)
 		verbose(env, " cb");
@@ -864,7 +865,8 @@ static inline u32 vlog_alignment(u32 pos)
 			BPF_LOG_MIN_ALIGNMENT) - pos - 1;
 }
 
-void print_insn_state(struct bpf_verifier_env *env, const struct bpf_func_state *state)
+void print_insn_state(struct bpf_verifier_env *env, const struct bpf_verifier_state *vstate,
+		      u32 frameno)
 {
 	if (env->prev_log_pos && env->prev_log_pos == env->log.end_pos) {
 		/* remove new line character */
@@ -873,5 +875,5 @@ void print_insn_state(struct bpf_verifier_env *env, const struct bpf_func_state
 	} else {
 		verbose(env, "%d:", env->insn_idx);
 	}
-	print_verifier_state(env, state, false);
+	print_verifier_state(env, vstate, frameno, false);
 }