Re: [PATCH bpf-next 07/14] bpf: Allow arguments without names in static functions in BTF

[Alan Maguire <alan.maguire@oracle.com>]

On 30/09/2026 20:31, Alexei Starovoitov wrote:
> From: Alexei Starovoitov <ast@kernel.org>
> 
> Some static functions in BTF of a Rust program have arguments without
> names:
> 
>   [71] FUNC_PROTO '(anon)' ret_type_id=0 vlen=1
>           '(anon)' type_id=72
>   [81] FUNC 'unwrap_failed' type_id=71 linkage=static
> 
> and the kernel rejects such BTF with "Invalid arg#1". It's 5 of 25
> static functions in scx_cosmos and 6 of 24 in scx_simple.
> 
> The verifier looks at types of the arguments. The names are printed only,
> as "(anon)" when there is none. Allow such static FUNC. Global functions
> are checked as before.
> 
> The test "func (Some arg has no name)" in prog_tests/btf.c has a static
> function. Make it global to keep the check.
> 
> Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Acked-by: Alan Maguire <alan.maguire@oracle.com>

> ---
>  kernel/bpf/btf.c                             | 4 ++++
>  tools/testing/selftests/bpf/prog_tests/btf.c | 5 +++--
>  2 files changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
> index d27af5d8e495..c9d4b709380c 100644
> --- a/kernel/bpf/btf.c
> +++ b/kernel/bpf/btf.c
> @@ -5752,6 +5752,10 @@ static int btf_func_check(struct btf_verifier_env *env,
>  		return -EINVAL;
>  	}
>  
> +	/* Rust leaves out names of some arguments of static functions */
> +	if (btf_func_linkage(t) == BTF_FUNC_STATIC)
> +		return 0;
> +
>  	args = (const struct btf_param *)(proto_type + 1);
>  	nr_args = btf_type_vlen(proto_type);
>  	for (i = 0; i < nr_args; i++) {


> diff --git a/tools/testing/selftests/bpf/prog_tests/btf.c b/tools/testing/selftests/bpf/prog_tests/btf.c
> index 207341f4bd99..21fdeeb23405 100644
> --- a/tools/testing/selftests/bpf/prog_tests/btf.c
> +++ b/tools/testing/selftests/bpf/prog_tests/btf.c
> @@ -2793,7 +2793,7 @@ static struct btf_raw_test raw_tests[] = {
>  },
>  
>  {
> -	.descr = "func (Some arg has no name)",
> +	.descr = "func (Some arg of global func has no name)",
>  	.raw_types = {
>  		BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),	/* [1] */
>  		BTF_TYPE_INT_ENC(0, 0, 0, 32, 4),		/* [2] */
> @@ -2802,7 +2802,8 @@ static struct btf_raw_test raw_tests[] = {
>  			BTF_FUNC_PROTO_ARG_ENC(NAME_TBD, 1),
>  			BTF_FUNC_PROTO_ARG_ENC(0, 2),
>  		/* void func(int a, unsigned int) */
> -		BTF_FUNC_ENC(NAME_TBD, 3),			/* [4] */
> +		BTF_TYPE_ENC(NAME_TBD,				/* [4] */
> +			     BTF_INFO_ENC(BTF_KIND_FUNC, 0, BTF_FUNC_GLOBAL), 3),
>  		BTF_END_RAW,
>  	},
>  	.str_sec = "\0a\0func",