Commit 1338b933 authored by Kui-Feng Lee's avatar Kui-Feng Lee Committed by Martin KaFai Lau
Browse files

bpf: pass btf object id in bpf_map_info. 



Include btf object id (btf_obj_id) in bpf_map_info so that tools (ex:
bpftools struct_ops dump) know the correct btf from the kernel to look up
type information of struct_ops types.

Since struct_ops types can be defined and registered in a module. The
type information of a struct_ops type are defined in the btf of the
module defining it.  The userspace tools need to know which btf is for
the module defining a struct_ops type.

Signed-off-by: default avatarKui-Feng Lee <thinker.li@gmail.com>
Link: https://lore.kernel.org/r/20240119225005.668602-7-thinker.li@gmail.com


Signed-off-by: default avatarMartin KaFai Lau <martin.lau@kernel.org>
parent 47f4f657

include/linux/bpf.h

+4 −0
Original line number Diff line number Diff line
@@ -1732,6 +1732,7 @@ struct bpf_dummy_ops { 
int bpf_struct_ops_test_run(struct bpf_prog *prog, const union bpf_attr *kattr,

			    union bpf_attr __user *uattr);

#endif

void bpf_map_struct_ops_info_fill(struct bpf_map_info *info, struct bpf_map *map);

#else

static inline const struct bpf_struct_ops_desc *bpf_struct_ops_find(u32 type_id)

{
@@ -1759,6 +1760,9 @@ static inline int bpf_struct_ops_link_create(union bpf_attr *attr) 
{

	return -EOPNOTSUPP;

}

static inline void bpf_map_struct_ops_info_fill(struct bpf_map_info *info, struct bpf_map *map)

{

}



#endif

include/uapi/linux/bpf.h

+1 −1
Original line number Diff line number Diff line
@@ -6487,7 +6487,7 @@ struct bpf_map_info { 
	__u32 btf_id;

	__u32 btf_key_type_id;

	__u32 btf_value_type_id;

	__u32 :32;	/* alignment pad */

	__u32 btf_vmlinux_id;

	__u64 map_extra;

} __attribute__((aligned(8)));

kernel/bpf/bpf_struct_ops.c

+7 −0
Original line number Diff line number Diff line
@@ -947,3 +947,10 @@ int bpf_struct_ops_link_create(union bpf_attr *attr) 
	kfree(link);

	return err;

}



void bpf_map_struct_ops_info_fill(struct bpf_map_info *info, struct bpf_map *map)

{

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



	info->btf_vmlinux_id = btf_obj_id(st_map->btf);

}

kernel/bpf/syscall.c

+2 −0
Original line number Diff line number Diff line
@@ -4691,6 +4691,8 @@ static int bpf_map_get_info_by_fd(struct file *file, 
		info.btf_value_type_id = map->btf_value_type_id;

	}

	info.btf_vmlinux_value_type_id = map->btf_vmlinux_value_type_id;

	if (map->map_type == BPF_MAP_TYPE_STRUCT_OPS)

		bpf_map_struct_ops_info_fill(&info, map);



	if (bpf_map_is_offloaded(map)) {

		err = bpf_map_offload_info_fill(&info, map);

tools/include/uapi/linux/bpf.h

+1 −1
Original line number Diff line number Diff line
@@ -6487,7 +6487,7 @@ struct bpf_map_info { 
	__u32 btf_id;

	__u32 btf_key_type_id;

	__u32 btf_value_type_id;

	__u32 :32;	/* alignment pad */

	__u32 btf_vmlinux_id;

	__u64 map_extra;

} __attribute__((aligned(8)));