Relax verifier's restriction that was meant to forbid tailcall usage
when subprog count was higher than 1.
Also, do not max out the stack depth of program that utilizes tailcalls.
Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@xxxxxxxxx>
---
kernel/bpf/verifier.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 644ee9286ecf..05034cff89ca 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -4384,10 +4384,12 @@ static int check_map_func_compatibility(struct bpf_verifier_env *env,
case BPF_FUNC_tail_call:
if (map->map_type != BPF_MAP_TYPE_PROG_ARRAY)
goto error;
+#if !defined(CONFIG_X86_64) || !defined(CONFIG_BPF_JIT_ALWAYS_ON)
if (env->subprog_cnt > 1) {
verbose(env, "tail_calls are not allowed in programs with bpf-to-bpf calls\n");
return -EINVAL;
}
+#endif
break;
case BPF_FUNC_perf_event_read:
case BPF_FUNC_perf_event_output:
@@ -10633,7 +10635,9 @@ static int fixup_bpf_calls(struct bpf_verifier_env *env)
* the program array.
*/
prog->cb_access = 1;
+#if !defined(CONFIG_X86_64) || !defined(CONFIG_BPF_JIT_ALWAYS_ON)
env->prog->aux->stack_depth = MAX_BPF_STACK;
+#endif
env->prog->aux->max_pkt_offset = MAX_PACKET_OFF;
/* mark bpf_tail_call as different opcode to avoid
--
2.20.1
