From 56351851479502e2d159aca40df6723ed3f856a9 Mon Sep 17 00:00:00 2001 From: Amery Hung Date: Wed, 3 Dec 2025 15:37:45 -0800 Subject: [PATCH] libbpf: Add support for associating BPF program with struct_ops Add low-level wrapper and libbpf API for BPF_PROG_ASSOC_STRUCT_OPS command in the bpf() syscall. Signed-off-by: Amery Hung Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20251203233748.668365-4-ameryhung@gmail.com --- src/bpf.c | 19 +++++++++++++++++++ src/bpf.h | 21 +++++++++++++++++++++ src/libbpf.c | 31 +++++++++++++++++++++++++++++++ src/libbpf.h | 16 ++++++++++++++++ src/libbpf.map | 2 ++ 5 files changed, 89 insertions(+) diff --git a/src/bpf.c b/src/bpf.c index b66f5fb..21b57a6 100644 --- a/src/bpf.c +++ b/src/bpf.c @@ -1397,3 +1397,22 @@ int bpf_prog_stream_read(int prog_fd, __u32 stream_id, void *buf, __u32 buf_len, err = sys_bpf(BPF_PROG_STREAM_READ_BY_FD, &attr, attr_sz); return libbpf_err_errno(err); } + +int bpf_prog_assoc_struct_ops(int prog_fd, int map_fd, + struct bpf_prog_assoc_struct_ops_opts *opts) +{ + const size_t attr_sz = offsetofend(union bpf_attr, prog_assoc_struct_ops); + union bpf_attr attr; + int err; + + if (!OPTS_VALID(opts, bpf_prog_assoc_struct_ops_opts)) + return libbpf_err(-EINVAL); + + memset(&attr, 0, attr_sz); + attr.prog_assoc_struct_ops.map_fd = map_fd; + attr.prog_assoc_struct_ops.prog_fd = prog_fd; + attr.prog_assoc_struct_ops.flags = OPTS_GET(opts, flags, 0); + + err = sys_bpf(BPF_PROG_ASSOC_STRUCT_OPS, &attr, attr_sz); + return libbpf_err_errno(err); +} diff --git a/src/bpf.h b/src/bpf.h index e983a3e..1f9c28d 100644 --- a/src/bpf.h +++ b/src/bpf.h @@ -733,6 +733,27 @@ struct bpf_prog_stream_read_opts { LIBBPF_API int bpf_prog_stream_read(int prog_fd, __u32 stream_id, void *buf, __u32 buf_len, struct bpf_prog_stream_read_opts *opts); +struct bpf_prog_assoc_struct_ops_opts { + size_t sz; + __u32 flags; + size_t :0; +}; +#define bpf_prog_assoc_struct_ops_opts__last_field flags + +/** + * @brief **bpf_prog_assoc_struct_ops** associates a BPF program with a + * struct_ops map. + * + * @param prog_fd FD for the BPF program + * @param map_fd FD for the struct_ops map to be associated with the BPF program + * @param opts optional options, can be NULL + * + * @return 0 on success; negative error code, otherwise (errno is also set to + * the error code) + */ +LIBBPF_API int bpf_prog_assoc_struct_ops(int prog_fd, int map_fd, + struct bpf_prog_assoc_struct_ops_opts *opts); + #ifdef __cplusplus } /* extern "C" */ #endif diff --git a/src/libbpf.c b/src/libbpf.c index 3dc8a80..c7c7901 100644 --- a/src/libbpf.c +++ b/src/libbpf.c @@ -14133,6 +14133,37 @@ int bpf_program__set_attach_target(struct bpf_program *prog, return 0; } +int bpf_program__assoc_struct_ops(struct bpf_program *prog, struct bpf_map *map, + struct bpf_prog_assoc_struct_ops_opts *opts) +{ + int prog_fd, map_fd; + + prog_fd = bpf_program__fd(prog); + if (prog_fd < 0) { + pr_warn("prog '%s': can't associate BPF program without FD (was it loaded?)\n", + prog->name); + return libbpf_err(-EINVAL); + } + + if (prog->type == BPF_PROG_TYPE_STRUCT_OPS) { + pr_warn("prog '%s': can't associate struct_ops program\n", prog->name); + return libbpf_err(-EINVAL); + } + + map_fd = bpf_map__fd(map); + if (map_fd < 0) { + pr_warn("map '%s': can't associate BPF map without FD (was it created?)\n", map->name); + return libbpf_err(-EINVAL); + } + + if (!bpf_map__is_struct_ops(map)) { + pr_warn("map '%s': can't associate non-struct_ops map\n", map->name); + return libbpf_err(-EINVAL); + } + + return bpf_prog_assoc_struct_ops(prog_fd, map_fd, opts); +} + int parse_cpu_mask_str(const char *s, bool **mask, int *mask_sz) { int err = 0, n, len, start, end = -1; diff --git a/src/libbpf.h b/src/libbpf.h index 65e68e9..e14d9e3 100644 --- a/src/libbpf.h +++ b/src/libbpf.h @@ -1006,6 +1006,22 @@ LIBBPF_API int bpf_program__set_attach_target(struct bpf_program *prog, int attach_prog_fd, const char *attach_func_name); +struct bpf_prog_assoc_struct_ops_opts; /* defined in bpf.h */ + +/** + * @brief **bpf_program__assoc_struct_ops()** associates a BPF program with a + * struct_ops map. + * + * @param prog BPF program + * @param map struct_ops map to be associated with the BPF program + * @param opts optional options, can be NULL + * + * @return 0, on success; negative error code, otherwise + */ +LIBBPF_API int +bpf_program__assoc_struct_ops(struct bpf_program *prog, struct bpf_map *map, + struct bpf_prog_assoc_struct_ops_opts *opts); + /** * @brief **bpf_object__find_map_by_name()** returns BPF map of * the given name, if it exists within the passed BPF object diff --git a/src/libbpf.map b/src/libbpf.map index 8ed8749..84fb90a 100644 --- a/src/libbpf.map +++ b/src/libbpf.map @@ -451,4 +451,6 @@ LIBBPF_1.7.0 { global: bpf_map__set_exclusive_program; bpf_map__exclusive_program; + bpf_prog_assoc_struct_ops; + bpf_program__assoc_struct_ops; } LIBBPF_1.6.0;