From 0a504fa1a780332760f2a4369a1adc3ee9f620d0 Mon Sep 17 00:00:00 2001 From: Ilya Leoshkevich Date: Tue, 21 Feb 2023 00:49:58 +0100 Subject: libbpf: Document bpf_{btf,link,map,prog}_get_info_by_fd() Replace the short informal description with the proper doc comments. Suggested-by: Andrii Nakryiko Signed-off-by: Ilya Leoshkevich Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20230220234958.764997-1-iii@linux.ibm.com --- tools/lib/bpf/bpf.h | 69 +++++++++++++++++++++++++++++++++++++++++++++++++---- 1 file changed, 64 insertions(+), 5 deletions(-) (limited to 'tools/lib/bpf/bpf.h') diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h index 9ed9bceb4111..f0f786373238 100644 --- a/tools/lib/bpf/bpf.h +++ b/tools/lib/bpf/bpf.h @@ -1,7 +1,7 @@ /* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */ /* - * common eBPF ELF operations. + * Common BPF ELF operations. * * Copyright (C) 2013-2015 Alexei Starovoitov * Copyright (C) 2015 Wang Nan @@ -386,14 +386,73 @@ LIBBPF_API int bpf_link_get_fd_by_id(__u32 id); LIBBPF_API int bpf_link_get_fd_by_id_opts(__u32 id, const struct bpf_get_fd_by_id_opts *opts); LIBBPF_API int bpf_obj_get_info_by_fd(int bpf_fd, void *info, __u32 *info_len); -/* Type-safe variants of bpf_obj_get_info_by_fd(). The callers still needs to - * pass info_len, which should normally be - * sizeof(struct bpf_{prog,map,btf,link}_info), in order to be compatible with - * different libbpf and kernel versions. + +/** + * @brief **bpf_prog_get_info_by_fd()** obtains information about the BPF + * program corresponding to *prog_fd*. + * + * Populates up to *info_len* bytes of *info* and updates *info_len* with the + * actual number of bytes written to *info*. + * + * @param prog_fd BPF program file descriptor + * @param info pointer to **struct bpf_prog_info** that will be populated with + * BPF program information + * @param info_len pointer to the size of *info*; on success updated with the + * number of bytes written to *info* + * @return 0, on success; negative error code, otherwise (errno is also set to + * the error code) */ LIBBPF_API int bpf_prog_get_info_by_fd(int prog_fd, struct bpf_prog_info *info, __u32 *info_len); + +/** + * @brief **bpf_map_get_info_by_fd()** obtains information about the BPF + * map corresponding to *map_fd*. + * + * Populates up to *info_len* bytes of *info* and updates *info_len* with the + * actual number of bytes written to *info*. + * + * @param map_fd BPF map file descriptor + * @param info pointer to **struct bpf_map_info** that will be populated with + * BPF map information + * @param info_len pointer to the size of *info*; on success updated with the + * number of bytes written to *info* + * @return 0, on success; negative error code, otherwise (errno is also set to + * the error code) + */ LIBBPF_API int bpf_map_get_info_by_fd(int map_fd, struct bpf_map_info *info, __u32 *info_len); + +/** + * @brief **bpf_btf_get_info_by_fd()** obtains information about the + * BTF object corresponding to *btf_fd*. + * + * Populates up to *info_len* bytes of *info* and updates *info_len* with the + * actual number of bytes written to *info*. + * + * @param btf_fd BTF object file descriptor + * @param info pointer to **struct bpf_btf_info** that will be populated with + * BTF object information + * @param info_len pointer to the size of *info*; on success updated with the + * number of bytes written to *info* + * @return 0, on success; negative error code, otherwise (errno is also set to + * the error code) + */ LIBBPF_API int bpf_btf_get_info_by_fd(int btf_fd, struct bpf_btf_info *info, __u32 *info_len); + +/** + * @brief **bpf_btf_get_info_by_fd()** obtains information about the BPF + * link corresponding to *link_fd*. + * + * Populates up to *info_len* bytes of *info* and updates *info_len* with the + * actual number of bytes written to *info*. + * + * @param link_fd BPF link file descriptor + * @param info pointer to **struct bpf_link_info** that will be populated with + * BPF link information + * @param info_len pointer to the size of *info*; on success updated with the + * number of bytes written to *info* + * @return 0, on success; negative error code, otherwise (errno is also set to + * the error code) + */ LIBBPF_API int bpf_link_get_info_by_fd(int link_fd, struct bpf_link_info *info, __u32 *info_len); struct bpf_prog_query_opts { -- cgit v1.2.3 From 912dd4b0c2a50a839301520badb241f36664ae07 Mon Sep 17 00:00:00 2001 From: Kui-Feng Lee Date: Wed, 22 Mar 2023 20:24:03 -0700 Subject: libbpf: Update a bpf_link with another struct_ops. Introduce bpf_link__update_map(), which allows to atomically update underlying struct_ops implementation for given struct_ops BPF link. Also add old_map_fd to struct bpf_link_update_opts to handle BPF_F_REPLACE feature. Signed-off-by: Kui-Feng Lee Link: https://lore.kernel.org/r/20230323032405.3735486-7-kuifeng@meta.com Signed-off-by: Martin KaFai Lau --- tools/lib/bpf/bpf.c | 8 +++++++- tools/lib/bpf/bpf.h | 3 ++- tools/lib/bpf/libbpf.c | 35 +++++++++++++++++++++++++++++++++++ tools/lib/bpf/libbpf.h | 1 + tools/lib/bpf/libbpf.map | 1 + 5 files changed, 46 insertions(+), 2 deletions(-) (limited to 'tools/lib/bpf/bpf.h') diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c index e750b6f5fcc3..767035900354 100644 --- a/tools/lib/bpf/bpf.c +++ b/tools/lib/bpf/bpf.c @@ -794,11 +794,17 @@ int bpf_link_update(int link_fd, int new_prog_fd, if (!OPTS_VALID(opts, bpf_link_update_opts)) return libbpf_err(-EINVAL); + if (OPTS_GET(opts, old_prog_fd, 0) && OPTS_GET(opts, old_map_fd, 0)) + return libbpf_err(-EINVAL); + memset(&attr, 0, attr_sz); attr.link_update.link_fd = link_fd; attr.link_update.new_prog_fd = new_prog_fd; attr.link_update.flags = OPTS_GET(opts, flags, 0); - attr.link_update.old_prog_fd = OPTS_GET(opts, old_prog_fd, 0); + if (OPTS_GET(opts, old_prog_fd, 0)) + attr.link_update.old_prog_fd = OPTS_GET(opts, old_prog_fd, 0); + else if (OPTS_GET(opts, old_map_fd, 0)) + attr.link_update.old_map_fd = OPTS_GET(opts, old_map_fd, 0); ret = sys_bpf(BPF_LINK_UPDATE, &attr, attr_sz); return libbpf_err_errno(ret); diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h index f0f786373238..b073e73439ef 100644 --- a/tools/lib/bpf/bpf.h +++ b/tools/lib/bpf/bpf.h @@ -336,8 +336,9 @@ struct bpf_link_update_opts { size_t sz; /* size of this struct for forward/backward compatibility */ __u32 flags; /* extra flags */ __u32 old_prog_fd; /* expected old program FD */ + __u32 old_map_fd; /* expected old map FD */ }; -#define bpf_link_update_opts__last_field old_prog_fd +#define bpf_link_update_opts__last_field old_map_fd LIBBPF_API int bpf_link_update(int link_fd, int new_prog_fd, const struct bpf_link_update_opts *opts); diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 4ff82baba0ea..2b5ea2500b80 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -11677,6 +11677,41 @@ struct bpf_link *bpf_map__attach_struct_ops(const struct bpf_map *map) return &link->link; } +/* + * Swap the back struct_ops of a link with a new struct_ops map. + */ +int bpf_link__update_map(struct bpf_link *link, const struct bpf_map *map) +{ + struct bpf_link_struct_ops *st_ops_link; + __u32 zero = 0; + int err; + + if (!bpf_map__is_struct_ops(map) || map->fd < 0) + return -EINVAL; + + st_ops_link = container_of(link, struct bpf_link_struct_ops, link); + /* Ensure the type of a link is correct */ + if (st_ops_link->map_fd < 0) + return -EINVAL; + + err = bpf_map_update_elem(map->fd, &zero, map->st_ops->kern_vdata, 0); + /* It can be EBUSY if the map has been used to create or + * update a link before. We don't allow updating the value of + * a struct_ops once it is set. That ensures that the value + * never changed. So, it is safe to skip EBUSY. + */ + if (err && err != -EBUSY) + return err; + + err = bpf_link_update(link->fd, map->fd, NULL); + if (err < 0) + return err; + + st_ops_link->map_fd = map->fd; + + return 0; +} + typedef enum bpf_perf_event_ret (*bpf_perf_event_print_t)(struct perf_event_header *hdr, void *private_data); diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h index db4992a036f8..1615e55e2e79 100644 --- a/tools/lib/bpf/libbpf.h +++ b/tools/lib/bpf/libbpf.h @@ -719,6 +719,7 @@ bpf_program__attach_freplace(const struct bpf_program *prog, struct bpf_map; LIBBPF_API struct bpf_link *bpf_map__attach_struct_ops(const struct bpf_map *map); +LIBBPF_API int bpf_link__update_map(struct bpf_link *link, const struct bpf_map *map); struct bpf_iter_attach_opts { size_t sz; /* size of this struct for forward/backward compatibility */ diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map index 50dde1f6521e..a5aa3a383d69 100644 --- a/tools/lib/bpf/libbpf.map +++ b/tools/lib/bpf/libbpf.map @@ -386,6 +386,7 @@ LIBBPF_1.1.0 { LIBBPF_1.2.0 { global: bpf_btf_get_info_by_fd; + bpf_link__update_map; bpf_link_get_info_by_fd; bpf_map_get_info_by_fd; bpf_prog_get_info_by_fd; -- cgit v1.2.3 From 94e55c0fdaf4268bdda2d3b375bc61daba056e85 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Thu, 6 Apr 2023 16:42:01 -0700 Subject: libbpf: Wire through log_true_size returned from kernel for BPF_PROG_LOAD Add output-only log_true_size field to bpf_prog_load_opts to return bpf_attr->log_true_size value back from bpf() syscall. Note, that we have to drop const modifier from opts in bpf_prog_load(). This could potentially cause compilation error for some users. But the usual practice is to define bpf_prog_load_ops as a local variable next to bpf_prog_load() call and pass pointer to it, so const vs non-const makes no difference and won't even come up in most (if not all) cases. There are no runtime and ABI backwards/forward compatibility issues at all. If user provides old struct bpf_prog_load_opts, libbpf won't set new fields. If old libbpf is provided new bpf_prog_load_opts, nothing will happen either as old libbpf doesn't yet know about this new field. Adding a new variant of bpf_prog_load() just for this seems like a big and unnecessary overkill. As a corroborating evidence is the fact that entire selftests/bpf code base required not adjustment whatsoever. Signed-off-by: Andrii Nakryiko Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20230406234205.323208-16-andrii@kernel.org --- tools/lib/bpf/bpf.c | 7 +++++-- tools/lib/bpf/bpf.h | 11 +++++++++-- 2 files changed, 14 insertions(+), 4 deletions(-) (limited to 'tools/lib/bpf/bpf.h') diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c index f1d04ee14d83..a031de0a707a 100644 --- a/tools/lib/bpf/bpf.c +++ b/tools/lib/bpf/bpf.c @@ -230,9 +230,9 @@ alloc_zero_tailing_info(const void *orecord, __u32 cnt, int bpf_prog_load(enum bpf_prog_type prog_type, const char *prog_name, const char *license, const struct bpf_insn *insns, size_t insn_cnt, - const struct bpf_prog_load_opts *opts) + struct bpf_prog_load_opts *opts) { - const size_t attr_sz = offsetofend(union bpf_attr, fd_array); + const size_t attr_sz = offsetofend(union bpf_attr, log_true_size); void *finfo = NULL, *linfo = NULL; const char *func_info, *line_info; __u32 log_size, log_level, attach_prog_fd, attach_btf_obj_fd; @@ -312,6 +312,7 @@ int bpf_prog_load(enum bpf_prog_type prog_type, } fd = sys_bpf_prog_load(&attr, attr_sz, attempts); + OPTS_SET(opts, log_true_size, attr.log_true_size); if (fd >= 0) return fd; @@ -352,6 +353,7 @@ int bpf_prog_load(enum bpf_prog_type prog_type, } fd = sys_bpf_prog_load(&attr, attr_sz, attempts); + OPTS_SET(opts, log_true_size, attr.log_true_size); if (fd >= 0) goto done; } @@ -366,6 +368,7 @@ int bpf_prog_load(enum bpf_prog_type prog_type, attr.log_level = 1; fd = sys_bpf_prog_load(&attr, attr_sz, attempts); + OPTS_SET(opts, log_true_size, attr.log_true_size); } done: /* free() doesn't affect errno, so we don't need to restore it */ diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h index b073e73439ef..cfa0cdfa50f8 100644 --- a/tools/lib/bpf/bpf.h +++ b/tools/lib/bpf/bpf.h @@ -96,13 +96,20 @@ struct bpf_prog_load_opts { __u32 log_level; __u32 log_size; char *log_buf; + /* output: actual total log contents size (including termintaing zero). + * It could be both larger than original log_size (if log was + * truncated), or smaller (if log buffer wasn't filled completely). + * If kernel doesn't support this feature, log_size is left unchanged. + */ + __u32 log_true_size; + size_t :0; }; -#define bpf_prog_load_opts__last_field log_buf +#define bpf_prog_load_opts__last_field log_true_size LIBBPF_API int bpf_prog_load(enum bpf_prog_type prog_type, const char *prog_name, const char *license, const struct bpf_insn *insns, size_t insn_cnt, - const struct bpf_prog_load_opts *opts); + struct bpf_prog_load_opts *opts); /* Flags to direct loading requirements */ #define MAPS_RELAX_COMPAT 0x01 -- cgit v1.2.3 From 097d8002b754a865beef880e5c1cdc3ef7c2163d Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Thu, 6 Apr 2023 16:42:02 -0700 Subject: libbpf: Wire through log_true_size for bpf_btf_load() API Similar to what we did for bpf_prog_load() in previous patch, wire returning of log_true_size value from kernel back to the user through OPTS out field. Signed-off-by: Andrii Nakryiko Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20230406234205.323208-17-andrii@kernel.org --- tools/lib/bpf/bpf.c | 6 ++++-- tools/lib/bpf/bpf.h | 11 +++++++++-- 2 files changed, 13 insertions(+), 4 deletions(-) (limited to 'tools/lib/bpf/bpf.h') diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c index a031de0a707a..128ac723c4ea 100644 --- a/tools/lib/bpf/bpf.c +++ b/tools/lib/bpf/bpf.c @@ -1083,9 +1083,9 @@ int bpf_raw_tracepoint_open(const char *name, int prog_fd) return libbpf_err_errno(fd); } -int bpf_btf_load(const void *btf_data, size_t btf_size, const struct bpf_btf_load_opts *opts) +int bpf_btf_load(const void *btf_data, size_t btf_size, struct bpf_btf_load_opts *opts) { - const size_t attr_sz = offsetofend(union bpf_attr, btf_log_level); + const size_t attr_sz = offsetofend(union bpf_attr, btf_log_true_size); union bpf_attr attr; char *log_buf; size_t log_size; @@ -1128,6 +1128,8 @@ int bpf_btf_load(const void *btf_data, size_t btf_size, const struct bpf_btf_loa attr.btf_log_level = 1; fd = sys_bpf_fd(BPF_BTF_LOAD, &attr, attr_sz); } + + OPTS_SET(opts, log_true_size, attr.btf_log_true_size); return libbpf_err_errno(fd); } diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h index cfa0cdfa50f8..a2c091389b18 100644 --- a/tools/lib/bpf/bpf.h +++ b/tools/lib/bpf/bpf.h @@ -124,11 +124,18 @@ struct bpf_btf_load_opts { char *log_buf; __u32 log_level; __u32 log_size; + /* output: actual total log contents size (including termintaing zero). + * It could be both larger than original log_size (if log was + * truncated), or smaller (if log buffer wasn't filled completely). + * If kernel doesn't support this feature, log_size is left unchanged. + */ + __u32 log_true_size; + size_t :0; }; -#define bpf_btf_load_opts__last_field log_size +#define bpf_btf_load_opts__last_field log_true_size LIBBPF_API int bpf_btf_load(const void *btf_data, size_t btf_size, - const struct bpf_btf_load_opts *opts); + struct bpf_btf_load_opts *opts); LIBBPF_API int bpf_map_update_elem(int fd, const void *key, const void *value, __u64 flags); -- cgit v1.2.3