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[173.230.99.219]) by smtp.gmail.com with ESMTPSA id f15sm4521028ilc.51.2020.08.14.12.16.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 14 Aug 2020 12:16:03 -0700 (PDT) From: YiFei Zhu To: bpf@vger.kernel.org Cc: Alexei Starovoitov , Daniel Borkmann , Stanislav Fomichev , Mahesh Bandewar , YiFei Zhu Subject: [RFC PATCH bpf-next 3/5] libbpf: Add BPF_PROG_ADD_MAP syscall and use it on .metadata section Date: Fri, 14 Aug 2020 14:15:56 -0500 Message-Id: X-Mailer: git-send-email 2.28.0 In-Reply-To: References: MIME-Version: 1.0 Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org From: YiFei Zhu The patch adds a simple wrapper bpf_prog_add_map around the syscall. And when using libbpf to load a program, it will probe the kernel for the support of this syscall, and scan for the .metadata ELF section and load it as an internal map like a .data section. In the case that kernel supports the BPF_PROG_ADD_MAP syscall and a .metadata section exists, the map will be explicitly attached to the program via the syscall immediately after program is loaded. -EEXIST is ignored for this syscall. Signed-off-by: YiFei Zhu --- tools/lib/bpf/bpf.c | 11 +++++ tools/lib/bpf/bpf.h | 1 + tools/lib/bpf/libbpf.c | 97 +++++++++++++++++++++++++++++++++++++++- tools/lib/bpf/libbpf.map | 1 + 4 files changed, 109 insertions(+), 1 deletion(-) diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c index eab14c97c15d..9b2173d4f92c 100644 --- a/tools/lib/bpf/bpf.c +++ b/tools/lib/bpf/bpf.c @@ -872,3 +872,14 @@ int bpf_enable_stats(enum bpf_stats_type type) return sys_bpf(BPF_ENABLE_STATS, &attr, sizeof(attr)); } + +int bpf_prog_add_map(int prog_fd, int map_fd, int flags) +{ + union bpf_attr attr = {}; + + attr.prog_add_map.prog_fd = prog_fd; + attr.prog_add_map.map_fd = map_fd; + attr.prog_add_map.flags = flags; + + return sys_bpf(BPF_PROG_ADD_MAP, &attr, sizeof(attr)); +} diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h index 28855fd5b5f4..d76fee8f84e0 100644 --- a/tools/lib/bpf/bpf.h +++ b/tools/lib/bpf/bpf.h @@ -240,6 +240,7 @@ LIBBPF_API int bpf_task_fd_query(int pid, int fd, __u32 flags, char *buf, enum bpf_stats_type; /* defined in up-to-date linux/bpf.h */ LIBBPF_API int bpf_enable_stats(enum bpf_stats_type type); +LIBBPF_API int bpf_prog_add_map(int prog_fd, int map_fd, int flags); #ifdef __cplusplus } /* extern "C" */ #endif diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 7be04e45d29c..3ab1cb1f2af3 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -180,6 +180,8 @@ struct bpf_capabilities { __u32 btf_func_global:1; /* kernel support for expected_attach_type in BPF_PROG_LOAD */ __u32 exp_attach_type:1; + /* kernel support for BPF_PROG_ADD_MAP */ + __u32 prog_add_map:1; }; enum reloc_type { @@ -288,6 +290,7 @@ struct bpf_struct_ops { #define KCONFIG_SEC ".kconfig" #define KSYMS_SEC ".ksyms" #define STRUCT_OPS_SEC ".struct_ops" +#define METADATA_SEC ".metadata" enum libbpf_map_type { LIBBPF_MAP_UNSPEC, @@ -295,6 +298,7 @@ enum libbpf_map_type { LIBBPF_MAP_BSS, LIBBPF_MAP_RODATA, LIBBPF_MAP_KCONFIG, + LIBBPF_MAP_METADATA, }; static const char * const libbpf_type_to_btf_name[] = { @@ -302,6 +306,7 @@ static const char * const libbpf_type_to_btf_name[] = { [LIBBPF_MAP_BSS] = BSS_SEC, [LIBBPF_MAP_RODATA] = RODATA_SEC, [LIBBPF_MAP_KCONFIG] = KCONFIG_SEC, + [LIBBPF_MAP_METADATA] = METADATA_SEC, }; struct bpf_map { @@ -380,6 +385,8 @@ struct bpf_object { size_t nr_maps; size_t maps_cap; + struct bpf_map *metadata_map; + char *kconfig; struct extern_desc *externs; int nr_extern; @@ -403,6 +410,7 @@ struct bpf_object { Elf_Data *rodata; Elf_Data *bss; Elf_Data *st_ops_data; + Elf_Data *metadata; size_t strtabidx; struct { GElf_Shdr shdr; @@ -418,6 +426,7 @@ struct bpf_object { int rodata_shndx; int bss_shndx; int st_ops_shndx; + int metadata_shndx; } efile; /* * All loaded bpf_object is linked in a list, which is @@ -1030,6 +1039,7 @@ static struct bpf_object *bpf_object__new(const char *path, obj->efile.obj_buf_sz = obj_buf_sz; obj->efile.maps_shndx = -1; obj->efile.btf_maps_shndx = -1; + obj->efile.metadata_shndx = -1; obj->efile.data_shndx = -1; obj->efile.rodata_shndx = -1; obj->efile.bss_shndx = -1; @@ -1391,6 +1401,9 @@ bpf_object__init_internal_map(struct bpf_object *obj, enum libbpf_map_type type, if (data) memcpy(map->mmaped, data, data_sz); + if (type == LIBBPF_MAP_METADATA) + obj->metadata_map = map; + pr_debug("map %td is \"%s\"\n", map - obj->maps, map->name); return 0; } @@ -1426,6 +1439,14 @@ static int bpf_object__init_global_data_maps(struct bpf_object *obj) if (err) return err; } + if (obj->efile.metadata_shndx >= 0) { + err = bpf_object__init_internal_map(obj, LIBBPF_MAP_METADATA, + obj->efile.metadata_shndx, + obj->efile.metadata->d_buf, + obj->efile.metadata->d_size); + if (err) + return err; + } return 0; } @@ -2665,6 +2686,9 @@ static int bpf_object__elf_collect(struct bpf_object *obj) } else if (strcmp(name, STRUCT_OPS_SEC) == 0) { obj->efile.st_ops_data = data; obj->efile.st_ops_shndx = idx; + } else if (strcmp(name, METADATA_SEC) == 0) { + obj->efile.metadata = data; + obj->efile.metadata_shndx = idx; } else { pr_debug("skip section(%d) %s\n", idx, name); } @@ -3078,7 +3102,8 @@ static bool bpf_object__shndx_is_data(const struct bpf_object *obj, { return shndx == obj->efile.data_shndx || shndx == obj->efile.bss_shndx || - shndx == obj->efile.rodata_shndx; + shndx == obj->efile.rodata_shndx || + shndx == obj->efile.metadata_shndx; } static bool bpf_object__shndx_is_maps(const struct bpf_object *obj, @@ -3099,6 +3124,8 @@ bpf_object__section_to_libbpf_map_type(const struct bpf_object *obj, int shndx) return LIBBPF_MAP_RODATA; else if (shndx == obj->efile.symbols_shndx) return LIBBPF_MAP_KCONFIG; + else if (shndx == obj->efile.metadata_shndx) + return LIBBPF_MAP_METADATA; else return LIBBPF_MAP_UNSPEC; } @@ -3633,6 +3660,59 @@ bpf_object__probe_exp_attach_type(struct bpf_object *obj) return 0; } +static int +bpf_object__probe_prog_add_map(struct bpf_object *obj) +{ + struct bpf_load_program_attr prog_attr; + struct bpf_create_map_attr map_attr; + char *cp, errmsg[STRERR_BUFSIZE]; + struct bpf_insn insns[] = { + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + }; + int prog, map; + + if (!obj->caps.global_data) + return 0; + + memset(&map_attr, 0, sizeof(map_attr)); + map_attr.map_type = BPF_MAP_TYPE_ARRAY; + map_attr.key_size = sizeof(int); + map_attr.value_size = 32; + map_attr.max_entries = 1; + + map = bpf_create_map_xattr(&map_attr); + if (map < 0) { + cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg)); + pr_warn("Error in %s():%s(%d). Couldn't create simple array map.\n", + __func__, cp, errno); + return -errno; + } + + memset(&prog_attr, 0, sizeof(prog_attr)); + prog_attr.prog_type = BPF_PROG_TYPE_SOCKET_FILTER; + prog_attr.insns = insns; + prog_attr.insns_cnt = ARRAY_SIZE(insns); + prog_attr.license = "GPL"; + + prog = bpf_load_program_xattr(&prog_attr, NULL, 0); + if (prog < 0) { + cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg)); + pr_warn("Error in %s():%s(%d). Couldn't create simple program.\n", + __func__, cp, errno); + + close(map); + return -errno; + } + + if (!bpf_prog_add_map(prog, map, 0)) + obj->caps.prog_add_map = 1; + + close(map); + close(prog); + return 0; +} + static int bpf_object__probe_caps(struct bpf_object *obj) { @@ -3644,6 +3724,7 @@ bpf_object__probe_caps(struct bpf_object *obj) bpf_object__probe_btf_datasec, bpf_object__probe_array_mmap, bpf_object__probe_exp_attach_type, + bpf_object__probe_prog_add_map, }; int i, ret; @@ -5404,6 +5485,20 @@ load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt, if (ret >= 0) { if (log_buf && load_attr.log_level) pr_debug("verifier log:\n%s", log_buf); + + if (prog->obj->metadata_map && prog->obj->caps.prog_add_map) { + if (bpf_prog_add_map(ret, bpf_map__fd(prog->obj->metadata_map), 0) && + errno != EEXIST) { + int fd = ret; + + ret = -errno; + cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg)); + pr_warn("add metadata map failed: %s\n", cp); + close(fd); + goto out; + } + } + *pfd = ret; ret = 0; goto out; diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map index 0c4722bfdd0a..86494a464c34 100644 --- a/tools/lib/bpf/libbpf.map +++ b/tools/lib/bpf/libbpf.map @@ -288,6 +288,7 @@ LIBBPF_0.1.0 { bpf_map__set_value_size; bpf_map__type; bpf_map__value_size; + bpf_prog_add_map; bpf_program__attach_xdp; bpf_program__autoload; bpf_program__is_sk_lookup;