diff options
author | KP Singh <kpsingh@google.com> | 2020-01-17 22:28:25 +0100 |
---|---|---|
committer | Alexei Starovoitov <ast@kernel.org> | 2020-01-17 13:59:34 -0800 |
commit | a6ed02cac690b635dbb938690e795812ce1e14ca (patch) | |
tree | ba5d20de0b6fc00988964ae2ab917a90651a08a1 /tools | |
parent | c701917e647c6aaee5e7bbb7a2c1ca99e8552c58 (diff) |
libbpf: Load btf_vmlinux only once per object.
As more programs (TRACING, STRUCT_OPS, and upcoming LSM) use vmlinux
BTF information, loading the BTF vmlinux information for every program
in an object is sub-optimal. The fix was originally proposed in:
https://lore.kernel.org/bpf/CAEf4BzZodr3LKJuM7QwD38BiEH02Cc1UbtnGpVkCJ00Mf+V_Qg@mail.gmail.com/
The btf_vmlinux is populated in the object if any of the programs in
the object requires it just before the programs are loaded and freed
after the programs finish loading.
Reported-by: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Signed-off-by: KP Singh <kpsingh@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Brendan Jackman <jackmanb@chromium.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200117212825.11755-1-kpsingh@chromium.org
Diffstat (limited to 'tools')
-rw-r--r-- | tools/lib/bpf/libbpf.c | 153 |
1 files changed, 101 insertions, 52 deletions
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index fc41c3f2e983..faab96a42141 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -385,6 +385,10 @@ struct bpf_object { struct list_head list; struct btf *btf; + /* Parse and load BTF vmlinux if any of the programs in the object need + * it at load time. + */ + struct btf *btf_vmlinux; struct btf_ext *btf_ext; void *priv; @@ -633,7 +637,8 @@ find_member_by_name(const struct btf *btf, const struct btf_type *t, } #define STRUCT_OPS_VALUE_PREFIX "bpf_struct_ops_" -#define STRUCT_OPS_VALUE_PREFIX_LEN (sizeof(STRUCT_OPS_VALUE_PREFIX) - 1) +static int find_btf_by_prefix_kind(const struct btf *btf, const char *prefix, + const char *name, __u32 kind); static int find_struct_ops_kern_types(const struct btf *btf, const char *tname, @@ -644,7 +649,6 @@ find_struct_ops_kern_types(const struct btf *btf, const char *tname, const struct btf_type *kern_type, *kern_vtype; const struct btf_member *kern_data_member; __s32 kern_vtype_id, kern_type_id; - char vtname[128] = STRUCT_OPS_VALUE_PREFIX; __u32 i; kern_type_id = btf__find_by_name_kind(btf, tname, BTF_KIND_STRUCT); @@ -660,13 +664,11 @@ find_struct_ops_kern_types(const struct btf *btf, const char *tname, * find "struct bpf_struct_ops_tcp_congestion_ops" from the * btf_vmlinux. */ - strncat(vtname + STRUCT_OPS_VALUE_PREFIX_LEN, tname, - sizeof(vtname) - STRUCT_OPS_VALUE_PREFIX_LEN - 1); - kern_vtype_id = btf__find_by_name_kind(btf, vtname, - BTF_KIND_STRUCT); + kern_vtype_id = find_btf_by_prefix_kind(btf, STRUCT_OPS_VALUE_PREFIX, + tname, BTF_KIND_STRUCT); if (kern_vtype_id < 0) { - pr_warn("struct_ops init_kern: struct %s is not found in kernel BTF\n", - vtname); + pr_warn("struct_ops init_kern: struct %s%s is not found in kernel BTF\n", + STRUCT_OPS_VALUE_PREFIX, tname); return kern_vtype_id; } kern_vtype = btf__type_by_id(btf, kern_vtype_id); @@ -683,8 +685,8 @@ find_struct_ops_kern_types(const struct btf *btf, const char *tname, break; } if (i == btf_vlen(kern_vtype)) { - pr_warn("struct_ops init_kern: struct %s data is not found in struct %s\n", - tname, vtname); + pr_warn("struct_ops init_kern: struct %s data is not found in struct %s%s\n", + tname, STRUCT_OPS_VALUE_PREFIX, tname); return -EINVAL; } @@ -835,7 +837,6 @@ static int bpf_map__init_kern_struct_ops(struct bpf_map *map, static int bpf_object__init_kern_struct_ops_maps(struct bpf_object *obj) { - struct btf *kern_btf = NULL; struct bpf_map *map; size_t i; int err; @@ -846,20 +847,12 @@ static int bpf_object__init_kern_struct_ops_maps(struct bpf_object *obj) if (!bpf_map__is_struct_ops(map)) continue; - if (!kern_btf) { - kern_btf = libbpf_find_kernel_btf(); - if (IS_ERR(kern_btf)) - return PTR_ERR(kern_btf); - } - - err = bpf_map__init_kern_struct_ops(map, obj->btf, kern_btf); - if (err) { - btf__free(kern_btf); + err = bpf_map__init_kern_struct_ops(map, obj->btf, + obj->btf_vmlinux); + if (err) return err; - } } - btf__free(kern_btf); return 0; } @@ -2357,6 +2350,41 @@ static int bpf_object__finalize_btf(struct bpf_object *obj) return 0; } +static inline bool libbpf_prog_needs_vmlinux_btf(struct bpf_program *prog) +{ + if (prog->type == BPF_PROG_TYPE_STRUCT_OPS) + return true; + + /* BPF_PROG_TYPE_TRACING programs which do not attach to other programs + * also need vmlinux BTF + */ + if (prog->type == BPF_PROG_TYPE_TRACING && !prog->attach_prog_fd) + return true; + + return false; +} + +static int bpf_object__load_vmlinux_btf(struct bpf_object *obj) +{ + struct bpf_program *prog; + int err; + + bpf_object__for_each_program(prog, obj) { + if (libbpf_prog_needs_vmlinux_btf(prog)) { + obj->btf_vmlinux = libbpf_find_kernel_btf(); + if (IS_ERR(obj->btf_vmlinux)) { + err = PTR_ERR(obj->btf_vmlinux); + pr_warn("Error loading vmlinux BTF: %d\n", err); + obj->btf_vmlinux = NULL; + return err; + } + return 0; + } + } + + return 0; +} + static int bpf_object__sanitize_and_load_btf(struct bpf_object *obj) { int err = 0; @@ -4884,18 +4912,14 @@ out: return ret; } -static int libbpf_find_attach_btf_id(const char *name, - enum bpf_attach_type attach_type, - __u32 attach_prog_fd); +static int libbpf_find_attach_btf_id(struct bpf_program *prog); int bpf_program__load(struct bpf_program *prog, char *license, __u32 kern_ver) { int err = 0, fd, i, btf_id; if (prog->type == BPF_PROG_TYPE_TRACING) { - btf_id = libbpf_find_attach_btf_id(prog->section_name, - prog->expected_attach_type, - prog->attach_prog_fd); + btf_id = libbpf_find_attach_btf_id(prog); if (btf_id <= 0) return btf_id; prog->attach_btf_id = btf_id; @@ -5273,10 +5297,15 @@ int bpf_object__load_xattr(struct bpf_object_load_attr *attr) err = err ? : bpf_object__resolve_externs(obj, obj->kconfig); err = err ? : bpf_object__sanitize_and_load_btf(obj); err = err ? : bpf_object__sanitize_maps(obj); + err = err ? : bpf_object__load_vmlinux_btf(obj); err = err ? : bpf_object__init_kern_struct_ops_maps(obj); err = err ? : bpf_object__create_maps(obj); err = err ? : bpf_object__relocate(obj, attr->target_btf_path); err = err ? : bpf_object__load_progs(obj, attr->log_level); + + btf__free(obj->btf_vmlinux); + obj->btf_vmlinux = NULL; + if (err) goto out; @@ -6497,34 +6526,52 @@ invalid_prog: return -EINVAL; } -#define BTF_PREFIX "btf_trace_" +#define BTF_TRACE_PREFIX "btf_trace_" +#define BTF_MAX_NAME_SIZE 128 + +static int find_btf_by_prefix_kind(const struct btf *btf, const char *prefix, + const char *name, __u32 kind) +{ + char btf_type_name[BTF_MAX_NAME_SIZE]; + int ret; + + ret = snprintf(btf_type_name, sizeof(btf_type_name), + "%s%s", prefix, name); + /* snprintf returns the number of characters written excluding the + * the terminating null. So, if >= BTF_MAX_NAME_SIZE are written, it + * indicates truncation. + */ + if (ret < 0 || ret >= sizeof(btf_type_name)) + return -ENAMETOOLONG; + return btf__find_by_name_kind(btf, btf_type_name, kind); +} + +static inline int __find_vmlinux_btf_id(struct btf *btf, const char *name, + enum bpf_attach_type attach_type) +{ + int err; + + if (attach_type == BPF_TRACE_RAW_TP) + err = find_btf_by_prefix_kind(btf, BTF_TRACE_PREFIX, name, + BTF_KIND_TYPEDEF); + else + err = btf__find_by_name_kind(btf, name, BTF_KIND_FUNC); + + return err; +} + int libbpf_find_vmlinux_btf_id(const char *name, enum bpf_attach_type attach_type) { - struct btf *btf = libbpf_find_kernel_btf(); - char raw_tp_btf[128] = BTF_PREFIX; - char *dst = raw_tp_btf + sizeof(BTF_PREFIX) - 1; - const char *btf_name; - int err = -EINVAL; - __u32 kind; + struct btf *btf; + btf = libbpf_find_kernel_btf(); if (IS_ERR(btf)) { pr_warn("vmlinux BTF is not found\n"); return -EINVAL; } - if (attach_type == BPF_TRACE_RAW_TP) { - /* prepend "btf_trace_" prefix per kernel convention */ - strncat(dst, name, sizeof(raw_tp_btf) - sizeof(BTF_PREFIX)); - btf_name = raw_tp_btf; - kind = BTF_KIND_TYPEDEF; - } else { - btf_name = name; - kind = BTF_KIND_FUNC; - } - err = btf__find_by_name_kind(btf, btf_name, kind); - btf__free(btf); - return err; + return __find_vmlinux_btf_id(btf, name, attach_type); } static int libbpf_find_prog_btf_id(const char *name, __u32 attach_prog_fd) @@ -6560,10 +6607,11 @@ out: return err; } -static int libbpf_find_attach_btf_id(const char *name, - enum bpf_attach_type attach_type, - __u32 attach_prog_fd) +static int libbpf_find_attach_btf_id(struct bpf_program *prog) { + enum bpf_attach_type attach_type = prog->expected_attach_type; + __u32 attach_prog_fd = prog->attach_prog_fd; + const char *name = prog->section_name; int i, err; if (!name) @@ -6578,8 +6626,9 @@ static int libbpf_find_attach_btf_id(const char *name, err = libbpf_find_prog_btf_id(name + section_defs[i].len, attach_prog_fd); else - err = libbpf_find_vmlinux_btf_id(name + section_defs[i].len, - attach_type); + err = __find_vmlinux_btf_id(prog->obj->btf_vmlinux, + name + section_defs[i].len, + attach_type); if (err <= 0) pr_warn("%s is not found in vmlinux BTF\n", name); return err; |