Re: [PATCH RFC bpf-next v2 4/4] bpf: Support 64-bit pointers to kfuncs

[Jiri Olsa <olsajiri@gmail.com>]

On Thu, Feb 16, 2023 at 12:59:31AM +0100, Ilya Leoshkevich wrote:

SNIP

> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> index 71158a6786a1..47d390923610 100644
> --- a/kernel/bpf/verifier.c
> +++ b/kernel/bpf/verifier.c
> @@ -2115,8 +2115,8 @@ static int add_subprog(struct bpf_verifier_env *env, int off)
>  struct bpf_kfunc_desc {
>  	struct btf_func_model func_model;
>  	u32 func_id;
> -	s32 imm;
>  	u16 offset;
> +	unsigned long addr;
>  };
>  
>  struct bpf_kfunc_btf {
> @@ -2166,6 +2166,19 @@ find_kfunc_desc(const struct bpf_prog *prog, u32 func_id, u16 offset)
>  		       sizeof(tab->descs[0]), kfunc_desc_cmp_by_id_off);
>  }
>  
> +int bpf_get_kfunc_addr(const struct bpf_prog *prog, u32 func_id, u16 offset,
> +		       u8 **func_addr)
> +{
> +	const struct bpf_kfunc_desc *desc;
> +
> +	desc = find_kfunc_desc(prog, func_id, offset);
> +	if (!desc)
> +		return -EFAULT;

should we warn here? this should alwayss succeed, right?

jirka

> +
> +	*func_addr = (u8 *)desc->addr;
> +	return 0;
> +}
> +

SNIP