[v5,bpf-next,12/14] libbpf: support attachment of BPF tracing programs to kernel modules

Message ID	20201203035204.1411380-13-andrii@kernel.org (mailing list archive)
State	Superseded
Delegated to:	BPF
Headers	show Return-Path: <bpf-owner@kernel.org> From: Andrii Nakryiko <andrii@kernel.org> To: <bpf@vger.kernel.org>, <netdev@vger.kernel.org>, <ast@fb.com>, <daniel@iogearbox.net> CC: <andrii@kernel.org>, <kernel-team@fb.com> Subject: [PATCH v5 bpf-next 12/14] libbpf: support attachment of BPF tracing programs to kernel modules Date: Wed, 2 Dec 2020 19:52:02 -0800 Message-ID: <20201203035204.1411380-13-andrii@kernel.org> In-Reply-To: <20201203035204.1411380-1-andrii@kernel.org> References: <20201203035204.1411380-1-andrii@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8BIT Content-Type: text/plain Precedence: bulk
Series	Support BTF-powered BPF tracing programs for kernel modules \| expand [v5,bpf-next,00/14] Support BTF-powered BPF tracing programs for kernel modules [v5,bpf-next,01/14] bpf: fix bpf_put_raw_tracepoint()'s use of __module_address() [v5,bpf-next,02/14] bpf: keep module's btf_data_size intact after load [v5,bpf-next,03/14] libbpf: add internal helper to load BTF data by FD [v5,bpf-next,04/14] libbpf: refactor CO-RE relocs to not assume a single BTF object [v5,bpf-next,05/14] libbpf: add kernel module BTF support for CO-RE relocations [v5,bpf-next,06/14] selftests/bpf: add bpf_testmod kernel module for testing [v5,bpf-next,07/14] selftests/bpf: add support for marking sub-tests as skipped [v5,bpf-next,08/14] selftests/bpf: add CO-RE relocs selftest relying on kernel module BTF [v5,bpf-next,09/14] bpf: remove hard-coded btf_vmlinux assumption from BPF verifier [v5,bpf-next,10/14] bpf: allow to specify kernel module BTFs when attaching BPF programs [v5,bpf-next,11/14] libbpf: factor out low-level BPF program loading helper [v5,bpf-next,12/14] libbpf: support attachment of BPF tracing programs to kernel modules [v5,bpf-next,13/14] selftests/bpf: add tp_btf CO-RE reloc test for modules [v5,bpf-next,14/14] selftests/bpf: add fentry/fexit/fmod_ret selftest for kernel module

Context	Check	Description
netdev/cover_letter	success	Link
netdev/fixes_present	success	Link
netdev/patch_count	success	Link
netdev/tree_selection	success	Clearly marked for bpf-next
netdev/subject_prefix	success	Link
netdev/source_inline	warning	Was 1 now: 1
netdev/verify_signedoff	success	Link
netdev/module_param	success	Was 0 now: 0
netdev/build_32bit	success	Errors and warnings before: 0 this patch: 0
netdev/kdoc	success	Errors and warnings before: 0 this patch: 0
netdev/verify_fixes	success	Link
netdev/checkpatch	warning	CHECK: Alignment should match open parenthesis WARNING: line length of 81 exceeds 80 columns WARNING: line length of 92 exceeds 80 columns WARNING: line length of 93 exceeds 80 columns WARNING: line length of 95 exceeds 80 columns WARNING: line length of 97 exceeds 80 columns WARNING: line length of 98 exceeds 80 columns
netdev/build_allmodconfig_warn	success	Errors and warnings before: 0 this patch: 0
netdev/header_inline	success	Link
netdev/stable	success	Stable not CCed

diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c index e371ef91f5e8..77f409f85b38 100644 --- a/tools/lib/bpf/bpf.c +++ b/tools/lib/bpf/bpf.c @@ -230,8 +230,11 @@ int libbpf__bpf_prog_load(const struct bpf_prog_load_params *load_attr) attr.prog_type = load_attr->prog_type; attr.expected_attach_type = load_attr->expected_attach_type; + if (load_attr->attach_prog_fd) + attr.attach_prog_fd = load_attr->attach_prog_fd; + else + attr.attach_btf_obj_fd = load_attr->attach_btf_obj_fd; attr.attach_btf_id = load_attr->attach_btf_id; - attr.attach_prog_fd = load_attr->attach_prog_fd; attr.prog_ifindex = load_attr->prog_ifindex; attr.kern_version = load_attr->kern_version; diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 0280df77cf5f..7e7b961ba131 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -278,6 +278,7 @@ struct bpf_program { enum bpf_prog_type type; enum bpf_attach_type expected_attach_type; int prog_ifindex; + __u32 attach_btf_obj_fd; __u32 attach_btf_id; __u32 attach_prog_fd; void *func_info; @@ -408,6 +409,7 @@ struct module_btf { struct btf *btf; char *name; __u32 id; + int fd; }; struct bpf_object { @@ -4766,7 +4768,7 @@ static int load_module_btfs(struct bpf_object *obj) if (err) { err = -errno; pr_warn("failed to get BTF object #%d info: %d\n", id, err); - return err; + goto err_out; } /* ignore non-module BTFs */ @@ -4776,25 +4778,33 @@ static int load_module_btfs(struct bpf_object *obj) } btf = btf_get_from_fd(fd, obj->btf_vmlinux); - close(fd); if (IS_ERR(btf)) { pr_warn("failed to load module [%s]'s BTF object #%d: %ld\n", name, id, PTR_ERR(btf)); - return PTR_ERR(btf); + err = PTR_ERR(btf); + goto err_out; } err = btf_ensure_mem((void **)&obj->btf_modules, &obj->btf_module_cap, sizeof(*obj->btf_modules), obj->btf_module_cnt + 1); if (err) - return err; + goto err_out; mod_btf = &obj->btf_modules[obj->btf_module_cnt++]; mod_btf->btf = btf; mod_btf->id = id; + mod_btf->fd = fd; mod_btf->name = strdup(name); - if (!mod_btf->name) - return -ENOMEM; + if (!mod_btf->name) { + err = -ENOMEM; + goto err_out; + } + continue; + +err_out: + close(fd); + return err; } return 0; @@ -6830,7 +6840,10 @@ load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt, load_attr.insn_cnt = insns_cnt; load_attr.license = license; load_attr.attach_btf_id = prog->attach_btf_id; - load_attr.attach_prog_fd = prog->attach_prog_fd; + if (prog->attach_prog_fd) + load_attr.attach_prog_fd = prog->attach_prog_fd; + else + load_attr.attach_btf_obj_fd = prog->attach_btf_obj_fd; load_attr.attach_btf_id = prog->attach_btf_id; load_attr.kern_version = kern_version; load_attr.prog_ifindex = prog->prog_ifindex; @@ -6926,11 +6939,11 @@ load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt, return ret; } -static int libbpf_find_attach_btf_id(struct bpf_program *prog); +static int libbpf_find_attach_btf_id(struct bpf_program *prog, int *btf_obj_fd, int *btf_type_id); int bpf_program__load(struct bpf_program *prog, char *license, __u32 kern_ver) { - int err = 0, fd, i, btf_id; + int err = 0, fd, i; if (prog->obj->loaded) { pr_warn("prog '%s': can't load after object was loaded\n", prog->name); @@ -6940,10 +6953,14 @@ int bpf_program__load(struct bpf_program *prog, char *license, __u32 kern_ver) if ((prog->type == BPF_PROG_TYPE_TRACING || prog->type == BPF_PROG_TYPE_LSM || prog->type == BPF_PROG_TYPE_EXT) && !prog->attach_btf_id) { - btf_id = libbpf_find_attach_btf_id(prog); - if (btf_id <= 0) - return btf_id; - prog->attach_btf_id = btf_id; + int btf_obj_fd = 0, btf_type_id = 0; + + err = libbpf_find_attach_btf_id(prog, &btf_obj_fd, &btf_type_id); + if (err) + return err; + + prog->attach_btf_obj_fd = btf_obj_fd; + prog->attach_btf_id = btf_type_id; } if (prog->instances.nr < 0 || !prog->instances.fds) { @@ -7453,6 +7470,7 @@ int bpf_object__load_xattr(struct bpf_object_load_attr *attr) /* clean up module BTFs */ for (i = 0; i < obj->btf_module_cnt; i++) { + close(obj->btf_modules[i].fd); btf__free(obj->btf_modules[i].btf); free(obj->btf_modules[i].name); } @@ -8795,8 +8813,8 @@ static int find_btf_by_prefix_kind(const struct btf *btf, const char *prefix, 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) +static inline int find_attach_btf_id(struct btf *btf, const char *name, + enum bpf_attach_type attach_type) { int err; @@ -8812,9 +8830,6 @@ static inline int __find_vmlinux_btf_id(struct btf *btf, const char *name, else err = btf__find_by_name_kind(btf, name, BTF_KIND_FUNC); - if (err <= 0) - pr_warn("%s is not found in vmlinux BTF\n", name); - return err; } @@ -8830,7 +8845,10 @@ int libbpf_find_vmlinux_btf_id(const char *name, return -EINVAL; } - err = __find_vmlinux_btf_id(btf, name, attach_type); + err = find_attach_btf_id(btf, name, attach_type); + if (err <= 0) + pr_warn("%s is not found in vmlinux BTF\n", name); + btf__free(btf); return err; } @@ -8868,11 +8886,49 @@ static int libbpf_find_prog_btf_id(const char *name, __u32 attach_prog_fd) return err; } -static int libbpf_find_attach_btf_id(struct bpf_program *prog) +static int find_kernel_btf_id(struct bpf_object *obj, const char *attach_name, + enum bpf_attach_type attach_type, + int *btf_obj_fd, int *btf_type_id) +{ + int ret, i; + + ret = find_attach_btf_id(obj->btf_vmlinux, attach_name, attach_type); + if (ret > 0) { + *btf_obj_fd = 0; /* vmlinux BTF */ + *btf_type_id = ret; + return 0; + } + if (ret != -ENOENT) + return ret; + + ret = load_module_btfs(obj); + if (ret) + return ret; + + for (i = 0; i < obj->btf_module_cnt; i++) { + const struct module_btf *mod = &obj->btf_modules[i]; + + ret = find_attach_btf_id(mod->btf, attach_name, attach_type); + if (ret > 0) { + *btf_obj_fd = mod->fd; + *btf_type_id = ret; + return 0; + } + if (ret == -ENOENT) + continue; + + return ret; + } + + return -ESRCH; +} + +static int libbpf_find_attach_btf_id(struct bpf_program *prog, int *btf_obj_fd, int *btf_type_id) { enum bpf_attach_type attach_type = prog->expected_attach_type; __u32 attach_prog_fd = prog->attach_prog_fd; - const char *name = prog->sec_name; + const char *name = prog->sec_name, *attach_name; + const struct bpf_sec_def *sec = NULL; int i, err; if (!name) @@ -8883,17 +8939,37 @@ static int libbpf_find_attach_btf_id(struct bpf_program *prog) continue; if (strncmp(name, section_defs[i].sec, section_defs[i].len)) continue; - if (attach_prog_fd) - err = libbpf_find_prog_btf_id(name + section_defs[i].len, - attach_prog_fd); - else - err = __find_vmlinux_btf_id(prog->obj->btf_vmlinux, - name + section_defs[i].len, - attach_type); + + sec = &section_defs[i]; + break; + } + + if (!sec) { + pr_warn("failed to identify BTF ID based on ELF section name '%s'\n", name); + return -ESRCH; + } + attach_name = name + sec->len; + + /* BPF program's BTF ID */ + if (attach_prog_fd) { + err = libbpf_find_prog_btf_id(attach_name, attach_prog_fd); + if (err < 0) { + pr_warn("failed to find BPF program (FD %d) BTF ID for '%s': %d\n", + attach_prog_fd, attach_name, err); + return err; + } + *btf_obj_fd = 0; + *btf_type_id = err; + return 0; + } + + /* kernel/module BTF ID */ + err = find_kernel_btf_id(prog->obj, attach_name, attach_type, btf_obj_fd, btf_type_id); + if (err) { + pr_warn("failed to find kernel BTF type ID of '%s': %d\n", attach_name, err); return err; } - pr_warn("failed to identify btf_id based on ELF section name '%s'\n", name); - return -ESRCH; + return 0; } int libbpf_attach_type_by_name(const char *name, @@ -10782,6 +10858,7 @@ int bpf_program__set_attach_target(struct bpf_program *prog, return btf_id; prog->attach_btf_id = btf_id; + prog->attach_btf_obj_fd = 0; prog->attach_prog_fd = attach_prog_fd; return 0; } diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h index 681073a67ae3..969d0ac592ba 100644 --- a/tools/lib/bpf/libbpf_internal.h +++ b/tools/lib/bpf/libbpf_internal.h @@ -160,6 +160,7 @@ struct bpf_prog_load_params { const char *license; __u32 kern_version; __u32 attach_prog_fd; + __u32 attach_btf_obj_fd; __u32 attach_btf_id; __u32 prog_ifindex; __u32 prog_btf_fd;

[v5,bpf-next,12/14] libbpf: support attachment of BPF tracing programs to kernel modules

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