[PATCH bpf] bpf: clarify a misleading verifier error message

[PATCH bpf] bpf: clarify a misleading verifier error message

[Andrea Terzolo]

The current verifier error message states that tail_calls are not
allowed in non-JITed programs with BPF-to-BPF calls. While this is
accurate, it is not the only scenario where this restriction applies.
Some architectures do not support this feature combination even when
programs are JITed. This update improves the error message to better
reflect these limitations.

Suggested-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Signed-off-by: Andrea Terzolo <andreaterzolo3@gmail.com>
---
 kernel/bpf/verifier.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 3303a3605..2e94fe5ea 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -9887,7 +9887,7 @@ static int check_map_func_compatibility(struct bpf_verifier_env *env,
 		if (map->map_type != BPF_MAP_TYPE_PROG_ARRAY)
 			goto error;
 		if (env->subprog_cnt > 1 && !allow_tail_call_in_subprogs(env)) {
-			verbose(env, "tail_calls are not allowed in non-JITed programs with bpf-to-bpf calls\n");
+			verbose(env, "mixing of tail_calls and bpf-to-bpf calls not supported\n");
 			return -EINVAL;
 		}
 		break;
-- 
2.43.0

Re: [PATCH bpf] bpf: clarify a misleading verifier error message

[Shung-Hsi Yu]

On Tue, Mar 18, 2025 at 09:35:45AM +0100, Andrea Terzolo wrote:
> The current verifier error message states that tail_calls are not
> allowed in non-JITed programs with BPF-to-BPF calls. While this is
> accurate, it is not the only scenario where this restriction applies.
> Some architectures do not support this feature combination even when
> programs are JITed. This update improves the error message to better
> reflect these limitations.
> 
> Suggested-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
> Signed-off-by: Andrea Terzolo <andreaterzolo3@gmail.com>

Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>

Re: [PATCH bpf] bpf: clarify a misleading verifier error message

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to bpf/bpf-next.git (master)
by Alexei Starovoitov <ast@kernel.org>:

On Tue, 18 Mar 2025 09:35:45 +0100 you wrote:
> The current verifier error message states that tail_calls are not
> allowed in non-JITed programs with BPF-to-BPF calls. While this is
> accurate, it is not the only scenario where this restriction applies.
> Some architectures do not support this feature combination even when
> programs are JITed. This update improves the error message to better
> reflect these limitations.
> 
> [...]

Here is the summary with links:
  - [bpf] bpf: clarify a misleading verifier error message
    https://git.kernel.org/bpf/bpf-next/c/a2598045ead9

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html