Add new function libbpf_find_kernel_btf_id() to find the btf type id of the kernel, including vmlinux and modules.
Signed-off-by: Menglong Dong <[email protected]> --- tools/lib/bpf/libbpf.c | 83 ++++++++++++++++++++++++++++++++++++++++ tools/lib/bpf/libbpf.h | 3 ++ tools/lib/bpf/libbpf.map | 1 + 3 files changed, 87 insertions(+) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 01f407591a92..44e34007de8c 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -9500,6 +9500,89 @@ int libbpf_find_vmlinux_btf_id(const char *name, return libbpf_err(err); } +int libbpf_find_kernel_btf_id(const char *name, + enum bpf_attach_type attach_type, + int *btf_obj_fd, int *btf_type_id) +{ + struct btf *btf, *vmlinux_btf; + struct bpf_btf_info info; + __u32 btf_id = 0, len; + char btf_name[64]; + int err, fd; + + vmlinux_btf = btf__load_vmlinux_btf(); + err = libbpf_get_error(vmlinux_btf); + if (err) + return libbpf_err(err); + + err = find_attach_btf_id(vmlinux_btf, name, attach_type); + if (err > 0) { + *btf_type_id = err; + *btf_obj_fd = 0; + err = 0; + goto out; + } + + /* kernel too old to support module BTFs */ + if (!feat_supported(NULL, FEAT_MODULE_BTF)) { + err = -EOPNOTSUPP; + goto out; + } + + while (true) { + err = bpf_btf_get_next_id(btf_id, &btf_id); + if (err) { + err = -errno; + goto out; + } + + fd = bpf_btf_get_fd_by_id(btf_id); + if (fd < 0) { + if (errno == ENOENT) + continue; + err = -errno; + goto out; + } + + len = sizeof(info); + memset(&info, 0, sizeof(info)); + info.name = ptr_to_u64(btf_name); + info.name_len = sizeof(btf_name); + + err = bpf_btf_get_info_by_fd(fd, &info, &len); + if (err) { + err = -errno; + goto fd_out; + } + + if (!info.kernel_btf || strcmp(btf_name, "vmlinux") == 0) { + close(fd); + continue; + } + + btf = btf_get_from_fd(fd, vmlinux_btf); + err = libbpf_get_error(btf); + if (err) + goto fd_out; + + err = find_attach_btf_id(btf, name, attach_type); + if (err > 0) { + *btf_type_id = err; + *btf_obj_fd = fd; + err = 0; + break; + } + close(fd); + continue; +fd_out: + close(fd); + break; + } +out: + btf__free(vmlinux_btf); + return err; +} + static int libbpf_find_prog_btf_id(const char *name, __u32 attach_prog_fd) { struct bpf_prog_info info; diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h index 5723cbbfcc41..ca151bbec833 100644 --- a/tools/lib/bpf/libbpf.h +++ b/tools/lib/bpf/libbpf.h @@ -306,6 +306,9 @@ LIBBPF_API int libbpf_attach_type_by_name(const char *name, enum bpf_attach_type *attach_type); LIBBPF_API int libbpf_find_vmlinux_btf_id(const char *name, enum bpf_attach_type attach_type); +LIBBPF_API int libbpf_find_kernel_btf_id(const char *name, + enum bpf_attach_type attach_type, + int *btf_obj_fd, int *btf_type_id); /* Accessors of bpf_program */ struct bpf_program; diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map index 86804fd90dd1..73c60f47b4bb 100644 --- a/tools/lib/bpf/libbpf.map +++ b/tools/lib/bpf/libbpf.map @@ -413,4 +413,5 @@ LIBBPF_1.4.0 { bpf_token_create; btf__new_split; btf_ext__raw_data; + libbpf_find_kernel_btf_id; } LIBBPF_1.3.0; -- 2.39.2
