On Sat, Aug 27, 2022 at 07:54:43PM -0700, Yonghong Song wrote:
SNIP
> diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
> index 903719b89238..4a081bfb4c8a 100644
> --- a/kernel/bpf/btf.c
> +++ b/kernel/bpf/btf.c
> @@ -5328,6 +5328,31 @@ static bool is_int_ptr(struct btf *btf, const struct btf_type *t)
> return btf_type_is_int(t);
> }
>
> +static u32 get_ctx_arg_idx(struct btf *btf, const struct btf_type *func_proto,
> + int off)
> +{
> + const struct btf_param *args;
> + const struct btf_type *t;
> + u32 offset = 0, nr_args;
> + int i;
> +
> + nr_args = btf_type_vlen(func_proto);
> + args = (const struct btf_param *)(func_proto + 1);
> + for (i = 0; i < nr_args; i++) {
> + t = btf_type_skip_modifiers(btf, args[i].type, NULL);
> + offset += btf_type_is_ptr(t) ? 8 : roundup(t->size, 8);
> + if (off < offset)
> + return i;
> + }
> +
> + t = btf_type_skip_modifiers(btf, func_proto->type, NULL);
> + offset += btf_type_is_ptr(t) ? 8 : roundup(t->size, 8);
> + if (off < offset)
> + return nr_args;
> +
> + return nr_args + 1;
> +}
> +
> bool btf_ctx_access(int off, int size, enum bpf_access_type type,
> const struct bpf_prog *prog,
> struct bpf_insn_access_aux *info)
> @@ -5347,7 +5372,7 @@ bool btf_ctx_access(int off, int size, enum bpf_access_type type,
> tname, off);
> return false;
> }
> - arg = off / 8;
> + arg = t == NULL ? (off / 8) : get_ctx_arg_idx(btf, t, off);
is the t == NULL check needed? we relied on t being defined later in the code
jirka
> args = (const struct btf_param *)(t + 1);
> /* if (t == NULL) Fall back to default BPF prog with
> * MAX_BPF_FUNC_REG_ARGS u64 arguments.
> @@ -5417,7 +5442,7 @@ bool btf_ctx_access(int off, int size, enum bpf_access_type type,
> /* skip modifiers */
> while (btf_type_is_modifier(t))
> t = btf_type_by_id(btf, t->type);
> - if (btf_type_is_small_int(t) || btf_is_any_enum(t))
> + if (btf_type_is_small_int(t) || btf_is_any_enum(t) || __btf_type_is_struct(t))
> /* accessing a scalar */
> return true;
> if (!btf_type_is_ptr(t)) {
> @@ -5881,7 +5906,7 @@ static int __get_type_size(struct btf *btf, u32 btf_id,
> if (btf_type_is_ptr(t))
> /* kernel size of pointer. Not BPF's size of pointer*/
> return sizeof(void *);
> - if (btf_type_is_int(t) || btf_is_any_enum(t))
> + if (btf_type_is_int(t) || btf_is_any_enum(t) || __btf_type_is_struct(t))
> return t->size;
> return -EINVAL;
SNIP
