libbpf: Find correct module BTFs for struct_ops maps and progs.

Locate the module BTFs for struct_ops maps and progs and pass them to the
kernel. This ensures that the kernel correctly resolves type IDs from the
appropriate module BTFs.

For the map of a struct_ops object, the FD of the module BTF is set to
bpf_map to keep a reference to the module BTF. The FD is passed to the
kernel as value_type_btf_obj_fd when the struct_ops object is loaded.

For a bpf_struct_ops prog, attach_btf_obj_fd of bpf_prog is the FD of a
module BTF in the kernel.

Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240119225005.668602-13-thinker.li@gmail.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
This commit is contained in:
Kui-Feng Lee
2024-01-19 14:50:03 -08:00
committed by Andrii Nakryiko
parent d767ead51f
commit 0b0dfaf1be
4 changed files with 38 additions and 12 deletions

View File

@@ -326,6 +326,7 @@ static int probe_map_create(enum bpf_map_type map_type)
case BPF_MAP_TYPE_STRUCT_OPS:
/* we'll get -ENOTSUPP for invalid BTF type ID for struct_ops */
opts.btf_vmlinux_value_type_id = 1;
opts.value_type_btf_obj_fd = -1;
exp_err = -524; /* -ENOTSUPP */
break;
case BPF_MAP_TYPE_BLOOM_FILTER: