On 12/08/2022 03:40, Hangbin Liu wrote:
> Similar with commit 10b62d6a38f7 ("libbpf: Add names for auxiliary maps"),
> let's make bpf_prog_load() also ignore name if kernel doesn't support
> program name.
>
> To achieve this, we need to call sys_bpf_prog_load() directly in
> probe_kern_prog_name() to avoid circular dependency. sys_bpf_prog_load()
> also need to be exported in the bpf.h file.
>
> Signed-off-by: Hangbin Liu <liuhangbin@xxxxxxxxx>
> ---
> tools/lib/bpf/bpf.c | 6 ++----
> tools/lib/bpf/bpf.h | 3 +++
> tools/lib/bpf/libbpf.c | 11 +++++++++--
> 3 files changed, 14 insertions(+), 6 deletions(-)
>
> diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
> index 6a96e665dc5d..575867d69496 100644
> --- a/tools/lib/bpf/bpf.c
> +++ b/tools/lib/bpf/bpf.c
> @@ -84,9 +84,7 @@ static inline int sys_bpf_fd(enum bpf_cmd cmd, union bpf_attr *attr,
> return ensure_good_fd(fd);
> }
>
> -#define PROG_LOAD_ATTEMPTS 5
> -
> -static inline int sys_bpf_prog_load(union bpf_attr *attr, unsigned int size, int attempts)
> +int sys_bpf_prog_load(union bpf_attr *attr, unsigned int size, int attempts)
> {
> int fd;
>
> @@ -263,7 +261,7 @@ int bpf_prog_load(enum bpf_prog_type prog_type,
> attr.prog_ifindex = OPTS_GET(opts, prog_ifindex, 0);
> attr.kern_version = OPTS_GET(opts, kern_version, 0);
>
> - if (prog_name)
> + if (prog_name && kernel_supports(NULL, FEAT_PROG_NAME))
> libbpf_strlcpy(attr.prog_name, prog_name, sizeof(attr.prog_name));
> attr.license = ptr_to_u64(license);
>
> diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
> index 9c50beabdd14..125c580e45f8 100644
> --- a/tools/lib/bpf/bpf.h
> +++ b/tools/lib/bpf/bpf.h
> @@ -35,6 +35,9 @@
> extern "C" {
> #endif
>
> +#define PROG_LOAD_ATTEMPTS 5
> +int sys_bpf_prog_load(union bpf_attr *attr, unsigned int size, int attempts);
> +
bpf.h is the user-facing header, should these go into libbpf_internal.h
instead?
By the way, I observe that libbpf_set_memlock_rlim() in bpf.h (below) is
not prefixed with LIBBPF_API, although it is exposed in the libbpf.map,
Andrii is this expected?
> int libbpf_set_memlock_rlim(size_t memlock_bytes);
>
> struct bpf_map_create_opts {
> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index 3f01f5cd8a4c..1bcb2735d3f1 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -4419,10 +4419,17 @@ static int probe_kern_prog_name(void)
> BPF_MOV64_IMM(BPF_REG_0, 0),
> BPF_EXIT_INSN(),
> };
> - int ret, insn_cnt = ARRAY_SIZE(insns);
> + union bpf_attr attr = {
> + .prog_type = BPF_PROG_TYPE_SOCKET_FILTER,
> + .prog_name = "test",
> + .license = ptr_to_u64("GPL"),
> + .insns = ptr_to_u64(insns),
> + .insn_cnt = (__u32)ARRAY_SIZE(insns),
> + };
I think you cannot initialise "attr" directly, you need a "memset(&attr,
0, sizeof(attr));" first, in case the struct contains padding between
the fields.
> + int ret;
>
> /* make sure loading with name works */
> - ret = bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, "test", "GPL", insns, insn_cnt, NULL);
> + ret = sys_bpf_prog_load(&attr, sizeof(attr), PROG_LOAD_ATTEMPTS);
> return probe_fd(ret);
> }
>
