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bpf: Use function pointers count as struct_ops links count

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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: Martin KaFai Lau <martin.lau@linux.dev>
Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
Link: https://lore.kernel.org/r/20241112145849.3436772-3-xukuohai@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Xu Kuohai 2024-11-12 22:58:48 +08:00 committed by Alexei Starovoitov
parent bd9d9b48eb
commit 821a3fa32b
1 changed files with 25 additions and 10 deletions
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35
kernel/bpf/bpf_struct_ops.c
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@ -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.
@ -480,11 +480,11 @@ 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]) {
bpf_link_put(st_map->links[i]);
st_map->links[i] = NULL;
}
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;
}
}
@ -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;
}