On Fri, Nov 29, 2024 at 5:29 AM Anton Protopopov <aspsk@xxxxxxxxxxxxx> wrote:
>
> Add new fd_array_cnt field to bpf_prog_load_opts
> and pass it in bpf_attr, if set.
>
> Signed-off-by: Anton Protopopov <aspsk@xxxxxxxxxxxxx>
> ---
> tools/lib/bpf/bpf.c | 5 +++--
> tools/lib/bpf/bpf.h | 5 ++++-
> tools/lib/bpf/features.c | 2 +-
> 3 files changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
> index becdfa701c75..0e7f59224936 100644
> --- a/tools/lib/bpf/bpf.c
> +++ b/tools/lib/bpf/bpf.c
> @@ -105,7 +105,7 @@ int sys_bpf_prog_load(union bpf_attr *attr, unsigned int size, int attempts)
> */
> int probe_memcg_account(int token_fd)
> {
> - const size_t attr_sz = offsetofend(union bpf_attr, prog_token_fd);
> + const size_t attr_sz = offsetofend(union bpf_attr, fd_array_cnt);
Thankfully this function doesn't set fd_array_cnt below.
Otherwise the detection of memcg would fail on older kernels.
Let's avoid people mindlessly adding init of fd_array_cnt here by accident.
Simply keep this line as-is.
offsetofend(.., prog_token_fd) is fine.
> struct bpf_insn insns[] = {
> BPF_EMIT_CALL(BPF_FUNC_ktime_get_coarse_ns),
> BPF_EXIT_INSN(),
> @@ -238,7 +238,7 @@ int bpf_prog_load(enum bpf_prog_type prog_type,
> const struct bpf_insn *insns, size_t insn_cnt,
> struct bpf_prog_load_opts *opts)
> {
> - const size_t attr_sz = offsetofend(union bpf_attr, prog_token_fd);
> + const size_t attr_sz = offsetofend(union bpf_attr, fd_array_cnt);
> void *finfo = NULL, *linfo = NULL;
> const char *func_info, *line_info;
> __u32 log_size, log_level, attach_prog_fd, attach_btf_obj_fd;
> @@ -311,6 +311,7 @@ int bpf_prog_load(enum bpf_prog_type prog_type,
> attr.line_info_cnt = OPTS_GET(opts, line_info_cnt, 0);
>
> attr.fd_array = ptr_to_u64(OPTS_GET(opts, fd_array, NULL));
> + attr.fd_array_cnt = OPTS_GET(opts, fd_array_cnt, 0);
>
> if (log_level) {
> attr.log_buf = ptr_to_u64(log_buf);
> diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
> index a4a7b1ad1b63..435da95d2058 100644
> --- a/tools/lib/bpf/bpf.h
> +++ b/tools/lib/bpf/bpf.h
> @@ -107,9 +107,12 @@ struct bpf_prog_load_opts {
> */
> __u32 log_true_size;
> __u32 token_fd;
> +
> + /* if set, provides the length of fd_array */
> + __u32 fd_array_cnt;
> size_t :0;
> };
> -#define bpf_prog_load_opts__last_field token_fd
> +#define bpf_prog_load_opts__last_field fd_array_cnt
>
> LIBBPF_API int bpf_prog_load(enum bpf_prog_type prog_type,
> const char *prog_name, const char *license,
> diff --git a/tools/lib/bpf/features.c b/tools/lib/bpf/features.c
> index 760657f5224c..5afc9555d9ac 100644
> --- a/tools/lib/bpf/features.c
> +++ b/tools/lib/bpf/features.c
> @@ -22,7 +22,7 @@ int probe_fd(int fd)
>
> static int probe_kern_prog_name(int token_fd)
> {
> - const size_t attr_sz = offsetofend(union bpf_attr, prog_token_fd);
> + const size_t attr_sz = offsetofend(union bpf_attr, fd_array_cnt);
Same here. Don't change it.
