Commit 821a3fa3 authored by Xu Kuohai's avatar Xu Kuohai Committed by Alexei Starovoitov
Browse files

bpf: Use function pointers count as struct_ops links count 



Only function pointers in a struct_ops structure can be linked to bpf
progs, so set the links count to the function pointers count, instead
of the total members count in the structure.

Suggested-by: default avatarMartin KaFai Lau <martin.lau@linux.dev>
Signed-off-by: default avatarXu Kuohai <xukuohai@huawei.com>
Link: https://lore.kernel.org/r/20241112145849.3436772-3-xukuohai@huaweicloud.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent bd9d9b48

kernel/bpf/bpf_struct_ops.c

+25 −10
Original line number Diff line number Diff line
@@ -31,7 +31,7 @@ struct bpf_struct_ops_map { 
	 * (in kvalue.data).

	 */

	struct bpf_link **links;

	u32 links_cnt;

	u32 funcs_cnt;

	u32 image_pages_cnt;

	/* image_pages is an array of pages that has all the trampolines

	 * that stores the func args before calling the bpf_prog.
@@ -480,13 +480,13 @@ static void bpf_struct_ops_map_put_progs(struct bpf_struct_ops_map *st_map) 
{

	u32 i;



	for (i = 0; i < st_map->links_cnt; i++) {

		if (st_map->links[i]) {

	for (i = 0; i < st_map->funcs_cnt; i++) {

		if (!st_map->links[i])

			break;

		bpf_link_put(st_map->links[i]);

		st_map->links[i] = NULL;

	}

}

}



static void bpf_struct_ops_map_free_image(struct bpf_struct_ops_map *st_map)

{
@@ -600,6 +600,7 @@ static long bpf_struct_ops_map_update_elem(struct bpf_map *map, void *key, 
	int prog_fd, err;

	u32 i, trampoline_start, image_off = 0;

	void *cur_image = NULL, *image = NULL;

	struct bpf_link **plink;



	if (flags)

		return -EINVAL;
@@ -638,6 +639,7 @@ static long bpf_struct_ops_map_update_elem(struct bpf_map *map, void *key, 
	udata = &uvalue->data;

	kdata = &kvalue->data;



	plink = st_map->links;

	module_type = btf_type_by_id(btf_vmlinux, st_ops_ids[IDX_MODULE_ID]);

	for_each_member(i, t, member) {

		const struct btf_type *mtype, *ptype;
@@ -713,7 +715,7 @@ static long bpf_struct_ops_map_update_elem(struct bpf_map *map, void *key, 
		}

		bpf_link_init(&link->link, BPF_LINK_TYPE_STRUCT_OPS,

			      &bpf_struct_ops_link_lops, prog);

		st_map->links[i] = &link->link;

		*plink++ = &link->link;



		trampoline_start = image_off;

		err = bpf_struct_ops_prepare_trampoline(tlinks, link,
@@ -894,6 +896,19 @@ static int bpf_struct_ops_map_alloc_check(union bpf_attr *attr) 
	return 0;

}



static u32 count_func_ptrs(const struct btf *btf, const struct btf_type *t)

{

	int i;

	u32 count;

	const struct btf_member *member;



	count = 0;

	for_each_member(i, t, member)

		if (btf_type_resolve_func_ptr(btf, member->type, NULL))

			count++;

	return count;

}



static struct bpf_map *bpf_struct_ops_map_alloc(union bpf_attr *attr)

{

	const struct bpf_struct_ops_desc *st_ops_desc;
@@ -960,9 +975,9 @@ static struct bpf_map *bpf_struct_ops_map_alloc(union bpf_attr *attr) 
	map = &st_map->map;



	st_map->uvalue = bpf_map_area_alloc(vt->size, NUMA_NO_NODE);

	st_map->links_cnt = btf_type_vlen(t);

	st_map->funcs_cnt = count_func_ptrs(btf, t);

	st_map->links =

		bpf_map_area_alloc(st_map->links_cnt * sizeof(struct bpf_links *),

		bpf_map_area_alloc(st_map->funcs_cnt * sizeof(struct bpf_link *),

				   NUMA_NO_NODE);

	if (!st_map->uvalue || !st_map->links) {

		ret = -ENOMEM;
@@ -993,7 +1008,7 @@ static u64 bpf_struct_ops_map_mem_usage(const struct bpf_map *map) 
	usage = sizeof(*st_map) +

			vt->size - sizeof(struct bpf_struct_ops_value);

	usage += vt->size;

	usage += btf_type_vlen(vt) * sizeof(struct bpf_links *);

	usage += st_map->funcs_cnt * sizeof(struct bpf_link *);

	usage += PAGE_SIZE;

	return usage;

}