From 08ac454e258e38813afb906650f19acce3afd982 Mon Sep 17 00:00:00 2001 From: Mykyta Yatsenko Date: Wed, 5 Jun 2024 18:51:35 +0100 Subject: [PATCH] libbpf: Auto-attach struct_ops BPF maps in BPF skeleton Similarly to `bpf_program`, support `bpf_map` automatic attachment in `bpf_object__attach_skeleton`. Currently only struct_ops maps could be attached. On bpftool side, code-generate links in skeleton struct for struct_ops maps. Similarly to `bpf_program_skeleton`, set links in `bpf_map_skeleton`. On libbpf side, extend `bpf_map` with new `autoattach` field to support enabling or disabling autoattach functionality, introducing getter/setter for this field. `bpf_object__(attach|detach)_skeleton` is extended with attaching/detaching struct_ops maps logic. Signed-off-by: Mykyta Yatsenko Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20240605175135.117127-1-yatsenko@meta.com --- tools/bpf/bpftool/gen.c | 36 +++++++++++++++++++--- tools/lib/bpf/libbpf.c | 64 ++++++++++++++++++++++++++++++++++++++-- tools/lib/bpf/libbpf.h | 18 +++++++++++ tools/lib/bpf/libbpf.map | 2 ++ 4 files changed, 113 insertions(+), 7 deletions(-) diff --git a/tools/bpf/bpftool/gen.c b/tools/bpf/bpftool/gen.c index d244a7de387e..4a4eedfcd479 100644 --- a/tools/bpf/bpftool/gen.c +++ b/tools/bpf/bpftool/gen.c @@ -848,7 +848,7 @@ out: } static void -codegen_maps_skeleton(struct bpf_object *obj, size_t map_cnt, bool mmaped) +codegen_maps_skeleton(struct bpf_object *obj, size_t map_cnt, bool mmaped, bool populate_links) { struct bpf_map *map; char ident[256]; @@ -888,6 +888,14 @@ codegen_maps_skeleton(struct bpf_object *obj, size_t map_cnt, bool mmaped) printf("\ts->maps[%zu].mmaped = (void **)&obj->%s;\n", i, ident); } + + if (populate_links && bpf_map__type(map) == BPF_MAP_TYPE_STRUCT_OPS) { + codegen("\ + \n\ + s->maps[%zu].link = &obj->links.%s;\n\ + ", + i, ident); + } i++; } } @@ -1141,7 +1149,7 @@ static void gen_st_ops_shadow_init(struct btf *btf, struct bpf_object *obj) static int do_skeleton(int argc, char **argv) { char header_guard[MAX_OBJ_NAME_LEN + sizeof("__SKEL_H__")]; - size_t map_cnt = 0, prog_cnt = 0, file_sz, mmap_sz; + size_t map_cnt = 0, prog_cnt = 0, attach_map_cnt = 0, file_sz, mmap_sz; DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts); char obj_name[MAX_OBJ_NAME_LEN] = "", *obj_data; struct bpf_object *obj = NULL; @@ -1225,6 +1233,10 @@ static int do_skeleton(int argc, char **argv) bpf_map__name(map)); continue; } + + if (bpf_map__type(map) == BPF_MAP_TYPE_STRUCT_OPS) + attach_map_cnt++; + map_cnt++; } bpf_object__for_each_program(prog, obj) { @@ -1297,6 +1309,9 @@ static int do_skeleton(int argc, char **argv) bpf_program__name(prog)); } printf("\t} progs;\n"); + } + + if (prog_cnt + attach_map_cnt) { printf("\tstruct {\n"); bpf_object__for_each_program(prog, obj) { if (use_loader) @@ -1306,6 +1321,19 @@ static int do_skeleton(int argc, char **argv) printf("\t\tstruct bpf_link *%s;\n", bpf_program__name(prog)); } + + bpf_object__for_each_map(map, obj) { + if (!get_map_ident(map, ident, sizeof(ident))) + continue; + if (bpf_map__type(map) != BPF_MAP_TYPE_STRUCT_OPS) + continue; + + if (use_loader) + printf("t\tint %s_fd;\n", ident); + else + printf("\t\tstruct bpf_link *%s;\n", ident); + } + printf("\t} links;\n"); } @@ -1448,7 +1476,7 @@ static int do_skeleton(int argc, char **argv) obj_name ); - codegen_maps_skeleton(obj, map_cnt, true /*mmaped*/); + codegen_maps_skeleton(obj, map_cnt, true /*mmaped*/, true /*links*/); codegen_progs_skeleton(obj, prog_cnt, true /*populate_links*/); codegen("\ @@ -1786,7 +1814,7 @@ static int do_subskeleton(int argc, char **argv) } } - codegen_maps_skeleton(obj, map_cnt, false /*mmaped*/); + codegen_maps_skeleton(obj, map_cnt, false /*mmaped*/, false /*links*/); codegen_progs_skeleton(obj, prog_cnt, false /*links*/); codegen("\ diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index d1627a2ca30b..4a28fac4908a 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -572,6 +572,7 @@ struct bpf_map { bool pinned; bool reused; bool autocreate; + bool autoattach; __u64 map_extra; }; @@ -1400,6 +1401,7 @@ static int init_struct_ops_maps(struct bpf_object *obj, const char *sec_name, map->def.value_size = type->size; map->def.max_entries = 1; map->def.map_flags = strcmp(sec_name, STRUCT_OPS_LINK_SEC) == 0 ? BPF_F_LINK : 0; + map->autoattach = true; map->st_ops = calloc(1, sizeof(*map->st_ops)); if (!map->st_ops) @@ -4819,6 +4821,20 @@ int bpf_map__set_autocreate(struct bpf_map *map, bool autocreate) return 0; } +int bpf_map__set_autoattach(struct bpf_map *map, bool autoattach) +{ + if (!bpf_map__is_struct_ops(map)) + return libbpf_err(-EINVAL); + + map->autoattach = autoattach; + return 0; +} + +bool bpf_map__autoattach(const struct bpf_map *map) +{ + return map->autoattach; +} + int bpf_map__reuse_fd(struct bpf_map *map, int fd) { struct bpf_map_info info; @@ -12900,8 +12916,10 @@ struct bpf_link *bpf_map__attach_struct_ops(const struct bpf_map *map) __u32 zero = 0; int err, fd; - if (!bpf_map__is_struct_ops(map)) + if (!bpf_map__is_struct_ops(map)) { + pr_warn("map '%s': can't attach non-struct_ops map\n", map->name); return libbpf_err_ptr(-EINVAL); + } if (map->fd < 0) { pr_warn("map '%s': can't attach BPF map without FD (was it created?)\n", map->name); @@ -13945,6 +13963,35 @@ int bpf_object__attach_skeleton(struct bpf_object_skeleton *s) */ } + /* Skeleton is created with earlier version of bpftool + * which does not support auto-attachment + */ + if (s->map_skel_sz < sizeof(struct bpf_map_skeleton)) + return 0; + + for (i = 0; i < s->map_cnt; i++) { + struct bpf_map *map = *s->maps[i].map; + struct bpf_link **link = s->maps[i].link; + + if (!map->autocreate || !map->autoattach) + continue; + + if (*link) + continue; + + /* only struct_ops maps can be attached */ + if (!bpf_map__is_struct_ops(map)) + continue; + *link = bpf_map__attach_struct_ops(map); + + if (!*link) { + err = -errno; + pr_warn("map '%s': failed to auto-attach: %d\n", + bpf_map__name(map), err); + return libbpf_err(err); + } + } + return 0; } @@ -13958,6 +14005,18 @@ void bpf_object__detach_skeleton(struct bpf_object_skeleton *s) bpf_link__destroy(*link); *link = NULL; } + + if (s->map_skel_sz < sizeof(struct bpf_map_skeleton)) + return; + + for (i = 0; i < s->map_cnt; i++) { + struct bpf_link **link = s->maps[i].link; + + if (link) { + bpf_link__destroy(*link); + *link = NULL; + } + } } void bpf_object__destroy_skeleton(struct bpf_object_skeleton *s) @@ -13965,8 +14024,7 @@ void bpf_object__destroy_skeleton(struct bpf_object_skeleton *s) if (!s) return; - if (s->progs) - bpf_object__detach_skeleton(s); + bpf_object__detach_skeleton(s); if (s->obj) bpf_object__close(*s->obj); free(s->maps); diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h index 26e4e35528c5..64a6a3d323e3 100644 --- a/tools/lib/bpf/libbpf.h +++ b/tools/lib/bpf/libbpf.h @@ -978,6 +978,23 @@ bpf_object__prev_map(const struct bpf_object *obj, const struct bpf_map *map); LIBBPF_API int bpf_map__set_autocreate(struct bpf_map *map, bool autocreate); LIBBPF_API bool bpf_map__autocreate(const struct bpf_map *map); +/** + * @brief **bpf_map__set_autoattach()** sets whether libbpf has to auto-attach + * map during BPF skeleton attach phase. + * @param map the BPF map instance + * @param autoattach whether to attach map during BPF skeleton attach phase + * @return 0 on success; negative error code, otherwise + */ +LIBBPF_API int bpf_map__set_autoattach(struct bpf_map *map, bool autoattach); + +/** + * @brief **bpf_map__autoattach()** returns whether BPF map is configured to + * auto-attach during BPF skeleton attach phase. + * @param map the BPF map instance + * @return true if map is set to auto-attach during skeleton attach phase; false, otherwise + */ +LIBBPF_API bool bpf_map__autoattach(const struct bpf_map *map); + /** * @brief **bpf_map__fd()** gets the file descriptor of the passed * BPF map @@ -1672,6 +1689,7 @@ struct bpf_map_skeleton { const char *name; struct bpf_map **map; void **mmaped; + struct bpf_link **link; }; struct bpf_prog_skeleton { diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map index c1ce8aa3520b..40595233dc7f 100644 --- a/tools/lib/bpf/libbpf.map +++ b/tools/lib/bpf/libbpf.map @@ -419,6 +419,8 @@ LIBBPF_1.4.0 { LIBBPF_1.5.0 { global: + bpf_map__autoattach; + bpf_map__set_autoattach; bpf_program__attach_sockmap; ring__consume_n; ring_buffer__consume_n;