Commit 47f4f657 authored by Kui-Feng Lee's avatar Kui-Feng Lee Committed by Martin KaFai Lau
Browse files

bpf: make struct_ops_map support btfs other than btf_vmlinux. 



Once new struct_ops can be registered from modules, btf_vmlinux is no
longer the only btf that struct_ops_map would face.  st_map should remember
what btf it should use to get type information.

Signed-off-by: default avatarKui-Feng Lee <thinker.li@gmail.com>
Link: https://lore.kernel.org/r/20240119225005.668602-6-thinker.li@gmail.com


Signed-off-by: default avatarMartin KaFai Lau <martin.lau@kernel.org>
parent e6199511

kernel/bpf/bpf_struct_ops.c

+15 −9
Original line number Diff line number Diff line
@@ -46,6 +46,8 @@ struct bpf_struct_ops_map { 
	 * "links[]".

	 */

	void *image;

	/* The owner moduler's btf. */

	struct btf *btf;

	/* uvalue->data stores the kernel struct

	 * (e.g. tcp_congestion_ops) that is more useful

	 * to userspace than the kvalue.  For example,
@@ -314,7 +316,7 @@ static void bpf_struct_ops_map_put_progs(struct bpf_struct_ops_map *st_map) 
	}

}



static int check_zero_holes(const struct btf_type *t, void *data)

static int check_zero_holes(const struct btf *btf, const struct btf_type *t, void *data)

{

	const struct btf_member *member;

	u32 i, moff, msize, prev_mend = 0;
@@ -326,8 +328,8 @@ static int check_zero_holes(const struct btf_type *t, void *data) 
		    memchr_inv(data + prev_mend, 0, moff - prev_mend))

			return -EINVAL;



		mtype = btf_type_by_id(btf_vmlinux, member->type);

		mtype = btf_resolve_size(btf_vmlinux, mtype, &msize);

		mtype = btf_type_by_id(btf, member->type);

		mtype = btf_resolve_size(btf, mtype, &msize);

		if (IS_ERR(mtype))

			return PTR_ERR(mtype);

		prev_mend = moff + msize;
@@ -401,12 +403,12 @@ static long bpf_struct_ops_map_update_elem(struct bpf_map *map, void *key, 
	if (*(u32 *)key != 0)

		return -E2BIG;



	err = check_zero_holes(st_ops_desc->value_type, value);

	err = check_zero_holes(st_map->btf, st_ops_desc->value_type, value);

	if (err)

		return err;



	uvalue = value;

	err = check_zero_holes(t, uvalue->data);

	err = check_zero_holes(st_map->btf, t, uvalue->data);

	if (err)

		return err;
@@ -442,7 +444,7 @@ static long bpf_struct_ops_map_update_elem(struct bpf_map *map, void *key, 
		u32 moff;



		moff = __btf_member_bit_offset(t, member) / 8;

		ptype = btf_type_resolve_ptr(btf_vmlinux, member->type, NULL);

		ptype = btf_type_resolve_ptr(st_map->btf, member->type, NULL);

		if (ptype == module_type) {

			if (*(void **)(udata + moff))

				goto reset_unlock;
@@ -467,8 +469,8 @@ static long bpf_struct_ops_map_update_elem(struct bpf_map *map, void *key, 
		if (!ptype || !btf_type_is_func_proto(ptype)) {

			u32 msize;



			mtype = btf_type_by_id(btf_vmlinux, member->type);

			mtype = btf_resolve_size(btf_vmlinux, mtype, &msize);

			mtype = btf_type_by_id(st_map->btf, member->type);

			mtype = btf_resolve_size(st_map->btf, mtype, &msize);

			if (IS_ERR(mtype)) {

				err = PTR_ERR(mtype);

				goto reset_unlock;
@@ -607,6 +609,7 @@ static long bpf_struct_ops_map_delete_elem(struct bpf_map *map, void *key) 
static void bpf_struct_ops_map_seq_show_elem(struct bpf_map *map, void *key,

					     struct seq_file *m)

{

	struct bpf_struct_ops_map *st_map = (struct bpf_struct_ops_map *)map;

	void *value;

	int err;
@@ -616,7 +619,8 @@ static void bpf_struct_ops_map_seq_show_elem(struct bpf_map *map, void *key, 


	err = bpf_struct_ops_map_sys_lookup_elem(map, key, value);

	if (!err) {

		btf_type_seq_show(btf_vmlinux, map->btf_vmlinux_value_type_id,

		btf_type_seq_show(st_map->btf,

				  map->btf_vmlinux_value_type_id,

				  value, m);

		seq_puts(m, "\n");

	}
@@ -726,6 +730,8 @@ static struct bpf_map *bpf_struct_ops_map_alloc(union bpf_attr *attr) 
		return ERR_PTR(-ENOMEM);

	}



	st_map->btf = btf_vmlinux;



	mutex_init(&st_map->lock);

	bpf_map_init_from_attr(map, attr);