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bpf: Show precise rejected function when attaching fexit/fmod_ret to __noreturn functions 

With this change, we know the precise rejected function name when
attaching fexit/fmod_ret to __noreturn functions from log.

$ ./fexit
libbpf: prog 'fexit': BPF program load failed: -EINVAL
libbpf: prog 'fexit': -- BEGIN PROG LOAD LOG --
Attaching fexit/fmod_ret to __noreturn function 'do_exit' is rejected.

Suggested-by: Leon Hwang <leon.hwang@linux.dev>
Signed-off-by: KaFai Wan <kafai.wan@linux.dev>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20250724151454.499040-2-kafai.wan@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
pull/1309/head
KaFai Wan 2025-07-24 23:14:51 +08:00 committed by Alexei Starovoitov
parent 5b4c54ac49
commit a5a6b29a70
2 changed files with 3 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
kernel/bpf/verifier.c
View File

@ -23985,7 +23985,8 @@ static int check_attach_btf_id(struct bpf_verifier_env *env)
} else if ((prog->expected_attach_type == BPF_TRACE_FEXIT || } else if ((prog->expected_attach_type == BPF_TRACE_FEXIT ||
prog->expected_attach_type == BPF_MODIFY_RETURN) && prog->expected_attach_type == BPF_MODIFY_RETURN) &&
btf_id_set_contains(&noreturn_deny, btf_id)) { btf_id_set_contains(&noreturn_deny, btf_id)) {
verbose(env, "Attaching fexit/fmod_ret to __noreturn functions is rejected.\n"); verbose(env, "Attaching fexit/fmod_ret to __noreturn function '%s' is rejected.\n",
tgt_info.tgt_name);
return -EINVAL; return -EINVAL;
} }

2
tools/testing/selftests/bpf/progs/fexit_noreturns.c
View File

@ -8,7 +8,7 @@
char _license[] SEC("license") = "GPL"; char _license[] SEC("license") = "GPL";
SEC("fexit/do_exit") SEC("fexit/do_exit")
__failure __msg("Attaching fexit/fmod_ret to __noreturn functions is rejected.") __failure __msg("Attaching fexit/fmod_ret to __noreturn function 'do_exit' is rejected.")
int BPF_PROG(noreturns) int BPF_PROG(noreturns)
{ {
return 0; return 0;