On Wed, Jun 17, 2020 at 01:43:45PM -0700, Andrey Ignatov wrote:
[ ... ]
> diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
> index e5c5305e859c..fa21b1e766ae 100644
> --- a/kernel/bpf/btf.c
> +++ b/kernel/bpf/btf.c
> @@ -3577,6 +3577,67 @@ btf_get_prog_ctx_type(struct bpf_verifier_log *log, struct btf *btf,
> return ctx_type;
> }
>
> +#define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type)
> +#define BPF_LINK_TYPE(_id, _name)
> +static const struct bpf_map_ops * const btf_vmlinux_map_ops[] = {
> +#define BPF_MAP_TYPE(_id, _ops) \
> + [_id] = &_ops,
> +#include <linux/bpf_types.h>
> +#undef BPF_MAP_TYPE
> +};
> +static u32 btf_vmlinux_map_ids[] = {
> +#define BPF_MAP_TYPE(_id, _ops) \
> + [_id] = (u32)-1,
> +#include <linux/bpf_types.h>
> +#undef BPF_MAP_TYPE
> +};
> +#undef BPF_PROG_TYPE
> +#undef BPF_LINK_TYPE
> +
> +static int btf_vmlinux_map_ids_init(const struct btf *btf,
> + struct bpf_verifier_log *log)
> +{
> + int base_btf_id, btf_id, i;
> + const char *btf_name;
> +
> + base_btf_id = btf_find_by_name_kind(btf, "bpf_map", BTF_KIND_STRUCT);
> + if (base_btf_id < 0)
> + return base_btf_id;
> +
> + BUILD_BUG_ON(ARRAY_SIZE(btf_vmlinux_map_ops) !=
> + ARRAY_SIZE(btf_vmlinux_map_ids));
> +
> + for (i = 0; i < ARRAY_SIZE(btf_vmlinux_map_ops); ++i) {
> + if (!btf_vmlinux_map_ops[i])
> + continue;
> + btf_name = btf_vmlinux_map_ops[i]->map_btf_name;
> + if (!btf_name) {
> + btf_vmlinux_map_ids[i] = base_btf_id;
> + continue;
> + }
> + btf_id = btf_find_by_name_kind(btf, btf_name, BTF_KIND_STRUCT);
> + if (btf_id < 0)
> + return btf_id;
> + btf_vmlinux_map_ids[i] = btf_id;
Since map_btf_name is already in map_ops, how about storing map_btf_id in
map_ops also?
btf_id 0 is "void" which is as good as -1, so there is no need
to modify all map_ops to init map_btf_id to -1.
> + btf_id = btf_find_by_name_kind_next(btf, btf_name,
> + BTF_KIND_STRUCT,
> + btf_id + 1);
> + if (btf_id > 0) {
> + bpf_log(log,
> + "Ambiguous btf_id for struct %s: %u, %u.\n",
> + btf_name, btf_vmlinux_map_ids[i], btf_id);
> + return -EINVAL;
> + }
> + }
> +
> + return 0;
> +}
> +
