From 7ca61121598338ab713a5c705a843f3b8fed9f90 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Tue, 5 Oct 2021 22:11:05 -0700 Subject: libbpf: Add API that copies all BTF types from one BTF object to another Add a bulk copying api, btf__add_btf(), that speeds up and simplifies appending entire contents of one BTF object to another one, taking care of copying BTF type data, adjusting resulting BTF type IDs according to their new locations in the destination BTF object, as well as copying and deduplicating all the referenced strings and updating all the string offsets in new BTF types as appropriate. This API is intended to be used from tools that are generating and otherwise manipulating BTFs generically, such as pahole. In pahole's case, this API is useful for speeding up parallelized BTF encoding, as it allows pahole to offload all the intricacies of BTF type copying to libbpf and handle the parallelization aspects of the process. Signed-off-by: Andrii Nakryiko Signed-off-by: Daniel Borkmann Acked-by: Song Liu Cc: Arnaldo Carvalho de Melo Link: https://lore.kernel.org/bpf/20211006051107.17921-2-andrii@kernel.org --- tools/lib/bpf/btf.h | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) (limited to 'tools/lib/bpf/btf.h') diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h index 2cfe31327920..864eb51753a1 100644 --- a/tools/lib/bpf/btf.h +++ b/tools/lib/bpf/btf.h @@ -173,6 +173,28 @@ LIBBPF_API int btf__find_str(struct btf *btf, const char *s); LIBBPF_API int btf__add_str(struct btf *btf, const char *s); LIBBPF_API int btf__add_type(struct btf *btf, const struct btf *src_btf, const struct btf_type *src_type); +/** + * @brief **btf__add_btf()** appends all the BTF types from *src_btf* into *btf* + * @param btf BTF object which all the BTF types and strings are added to + * @param src_btf BTF object which all BTF types and referenced strings are copied from + * @return BTF type ID of the first appended BTF type, or negative error code + * + * **btf__add_btf()** can be used to simply and efficiently append the entire + * contents of one BTF object to another one. All the BTF type data is copied + * over, all referenced type IDs are adjusted by adding a necessary ID offset. + * Only strings referenced from BTF types are copied over and deduplicated, so + * if there were some unused strings in *src_btf*, those won't be copied over, + * which is consistent with the general string deduplication semantics of BTF + * writing APIs. + * + * If any error is encountered during this process, the contents of *btf* is + * left intact, which means that **btf__add_btf()** follows the transactional + * semantics and the operation as a whole is all-or-nothing. + * + * *src_btf* has to be non-split BTF, as of now copying types from split BTF + * is not supported and will result in -ENOTSUP error code returned. + */ +LIBBPF_API int btf__add_btf(struct btf *btf, const struct btf *src_btf); LIBBPF_API int btf__add_int(struct btf *btf, const char *name, size_t byte_sz, int encoding); LIBBPF_API int btf__add_float(struct btf *btf, const char *name, size_t byte_sz); -- cgit From 223f903e9c832699f4e5f422281a60756c1c6cfe Mon Sep 17 00:00:00 2001 From: Yonghong Song Date: Tue, 12 Oct 2021 09:48:38 -0700 Subject: bpf: Rename BTF_KIND_TAG to BTF_KIND_DECL_TAG Patch set [1] introduced BTF_KIND_TAG to allow tagging declarations for struct/union, struct/union field, var, func and func arguments and these tags will be encoded into dwarf. They are also encoded to btf by llvm for the bpf target. After BTF_KIND_TAG is introduced, we intended to use it for kernel __user attributes. But kernel __user is actually a type attribute. Upstream and internal discussion showed it is not a good idea to mix declaration attribute and type attribute. So we proposed to introduce btf_type_tag as a type attribute and existing btf_tag renamed to btf_decl_tag ([2]). This patch renamed BTF_KIND_TAG to BTF_KIND_DECL_TAG and some other declarations with *_tag to *_decl_tag to make it clear the tag is for declaration. In the future, BTF_KIND_TYPE_TAG might be introduced per [3]. [1] https://lore.kernel.org/bpf/20210914223004.244411-1-yhs@fb.com/ [2] https://reviews.llvm.org/D111588 [3] https://reviews.llvm.org/D111199 Fixes: b5ea834dde6b ("bpf: Support for new btf kind BTF_KIND_TAG") Fixes: 5b84bd10363e ("libbpf: Add support for BTF_KIND_TAG") Fixes: 5c07f2fec003 ("bpftool: Add support for BTF_KIND_TAG") Signed-off-by: Yonghong Song Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20211012164838.3345699-1-yhs@fb.com --- tools/lib/bpf/btf.h | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) (limited to 'tools/lib/bpf/btf.h') diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h index 864eb51753a1..4011e206e6f7 100644 --- a/tools/lib/bpf/btf.h +++ b/tools/lib/bpf/btf.h @@ -236,7 +236,7 @@ LIBBPF_API int btf__add_datasec_var_info(struct btf *btf, int var_type_id, __u32 offset, __u32 byte_sz); /* tag construction API */ -LIBBPF_API int btf__add_tag(struct btf *btf, const char *value, int ref_type_id, +LIBBPF_API int btf__add_decl_tag(struct btf *btf, const char *value, int ref_type_id, int component_idx); struct btf_dedup_opts { @@ -426,9 +426,9 @@ static inline bool btf_is_float(const struct btf_type *t) return btf_kind(t) == BTF_KIND_FLOAT; } -static inline bool btf_is_tag(const struct btf_type *t) +static inline bool btf_is_decl_tag(const struct btf_type *t) { - return btf_kind(t) == BTF_KIND_TAG; + return btf_kind(t) == BTF_KIND_DECL_TAG; } static inline __u8 btf_int_encoding(const struct btf_type *t) @@ -499,10 +499,10 @@ btf_var_secinfos(const struct btf_type *t) return (struct btf_var_secinfo *)(t + 1); } -struct btf_tag; -static inline struct btf_tag *btf_tag(const struct btf_type *t) +struct btf_decl_tag; +static inline struct btf_decl_tag *btf_decl_tag(const struct btf_type *t) { - return (struct btf_tag *)(t + 1); + return (struct btf_decl_tag *)(t + 1); } #ifdef __cplusplus -- cgit From b96c07f3b5ae6944eb52fd96a322340aa80aef5d Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Wed, 20 Oct 2021 18:43:55 -0700 Subject: libbpf: Deprecate btf__finalize_data() and move it into libbpf.c There isn't a good use case where anyone but libbpf itself needs to call btf__finalize_data(). It was implemented for internal use and it's not clear why it was made into public API in the first place. To function, it requires active ELF data, which is stored inside bpf_object for the duration of opening phase only. But the only BTF that needs bpf_object's ELF is that bpf_object's BTF itself, which libbpf fixes up automatically during bpf_object__open() operation anyways. There is no need for any additional fix up and no reasonable scenario where it's useful and appropriate. Thus, btf__finalize_data() is just an API atavism and is better removed. So this patch marks it as deprecated immediately (v0.6+) and moves the code from btf.c into libbpf.c where it's used in the context of bpf_object opening phase. Such code co-location allows to make code structure more straightforward and remove bpf_object__section_size() and bpf_object__variable_offset() internal helpers from libbpf_internal.h, making them static. Their naming is also adjusted to not create a wrong illusion that they are some sort of method of bpf_object. They are internal helpers and are called appropriately. This is part of libbpf 1.0 effort ([0]). [0] Closes: https://github.com/libbpf/libbpf/issues/276 Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Acked-by: Song Liu Link: https://lore.kernel.org/bpf/20211021014404.2635234-2-andrii@kernel.org --- tools/lib/bpf/btf.h | 1 + 1 file changed, 1 insertion(+) (limited to 'tools/lib/bpf/btf.h') diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h index 4011e206e6f7..c9364be42035 100644 --- a/tools/lib/bpf/btf.h +++ b/tools/lib/bpf/btf.h @@ -123,6 +123,7 @@ LIBBPF_API struct btf *btf__load_from_kernel_by_id_split(__u32 id, struct btf *b LIBBPF_DEPRECATED_SINCE(0, 6, "use btf__load_from_kernel_by_id instead") LIBBPF_API int btf__get_from_id(__u32 id, struct btf **btf); +LIBBPF_DEPRECATED_SINCE(0, 6, "intended for internal libbpf use only") LIBBPF_API int btf__finalize_data(struct bpf_object *obj, struct btf *btf); LIBBPF_DEPRECATED_SINCE(0, 6, "use btf__load_into_kernel instead") LIBBPF_API int btf__load(struct btf *btf); -- cgit From 6a886de070fad850d6cb74a787c9ed017303d9ac Mon Sep 17 00:00:00 2001 From: Hengqi Chen Date: Fri, 22 Oct 2021 21:06:19 +0800 Subject: libbpf: Add btf__type_cnt() and btf__raw_data() APIs Add btf__type_cnt() and btf__raw_data() APIs and deprecate btf__get_nr_type() and btf__get_raw_data() since the old APIs don't follow the libbpf naming convention for getters which omit 'get' in the name (see [0]). btf__raw_data() is just an alias to the existing btf__get_raw_data(). btf__type_cnt() now returns the number of all types of the BTF object including 'void'. [0] Closes: https://github.com/libbpf/libbpf/issues/279 Signed-off-by: Hengqi Chen Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20211022130623.1548429-2-hengqi.chen@gmail.com --- tools/lib/bpf/btf.h | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'tools/lib/bpf/btf.h') diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h index c9364be42035..bc005ba3ceec 100644 --- a/tools/lib/bpf/btf.h +++ b/tools/lib/bpf/btf.h @@ -132,7 +132,9 @@ LIBBPF_API __s32 btf__find_by_name(const struct btf *btf, const char *type_name); LIBBPF_API __s32 btf__find_by_name_kind(const struct btf *btf, const char *type_name, __u32 kind); +LIBBPF_DEPRECATED_SINCE(0, 7, "use btf__type_cnt() instead; note that btf__get_nr_types() == btf__type_cnt() - 1") LIBBPF_API __u32 btf__get_nr_types(const struct btf *btf); +LIBBPF_API __u32 btf__type_cnt(const struct btf *btf); LIBBPF_API const struct btf *btf__base_btf(const struct btf *btf); LIBBPF_API const struct btf_type *btf__type_by_id(const struct btf *btf, __u32 id); @@ -145,7 +147,9 @@ LIBBPF_API int btf__resolve_type(const struct btf *btf, __u32 type_id); LIBBPF_API int btf__align_of(const struct btf *btf, __u32 id); LIBBPF_API int btf__fd(const struct btf *btf); LIBBPF_API void btf__set_fd(struct btf *btf, int fd); +LIBBPF_DEPRECATED_SINCE(0, 7, "use btf__raw_data() instead") LIBBPF_API const void *btf__get_raw_data(const struct btf *btf, __u32 *size); +LIBBPF_API const void *btf__raw_data(const struct btf *btf, __u32 *size); LIBBPF_API const char *btf__name_by_offset(const struct btf *btf, __u32 offset); LIBBPF_API const char *btf__str_by_offset(const struct btf *btf, __u32 offset); LIBBPF_API int btf__get_map_kv_tids(const struct btf *btf, const char *map_name, -- cgit