bpf: include backedges in peak_states stat

Count states accumulated in bpf_scc_visit->backedges in
env->peak_states.

Signed-off-by: Eduard Zingerman <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Alexei Starovoitov <[e-mail]>

include/linux/bpf_verifier.h

···
 	 */
 	struct bpf_verifier_state *entry_state;
 	struct bpf_scc_backedge *backedges; /* list of backedges */
+	u32 num_backedges;
 };
 
 /* An array of bpf_scc_visit structs sharing tht same bpf_scc_callchain->scc
···
 	u32 longest_mark_read_walk;
 	u32 free_list_size;
 	u32 explored_states_size;
+	u32 num_backedges;
 	bpfptr_t fd_array;
 
 	/* bit mask to keep track of whether a register has been accessed

kernel/bpf/verifier.c

···
 {
 	u32 cur_states;
 
-	cur_states = env->explored_states_size + env->free_list_size;
+	cur_states = env->explored_states_size + env->free_list_size + env->num_backedges;
 	env->peak_states = max(env->peak_states, cur_states);
 }
 
···
 	if (env->log.level & BPF_LOG_LEVEL2)
 		verbose(env, "SCC exit %s\n", format_callchain(env, &callchain));
 	visit->entry_state = NULL;
+	env->num_backedges -= visit->num_backedges;
+	visit->num_backedges = 0;
+	update_peak_states(env);
 	return propagate_backedges(env, visit);
 }
 
···
 		verbose(env, "SCC backedge %s\n", format_callchain(env, &callchain));
 	backedge->next = visit->backedges;
 	visit->backedges = backedge;
+	visit->num_backedges++;
+	env->num_backedges++;
+	update_peak_states(env);
 	return 0;
 }