From b8c54ea455dc2e0bda7ea9b0370279c224e21045 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Thu, 14 Nov 2019 10:57:06 -0800 Subject: libbpf: Add support to attach to fentry/fexit tracing progs Teach libbpf to recognize tracing programs types and attach them to fentry/fexit. Signed-off-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann Acked-by: Song Liu Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20191114185720.1641606-7-ast@kernel.org --- tools/include/uapi/linux/bpf.h | 2 + tools/lib/bpf/libbpf.c | 99 +++++++++++++++++++++++++++++++----------- tools/lib/bpf/libbpf.h | 4 ++ tools/lib/bpf/libbpf.map | 2 + 4 files changed, 82 insertions(+), 25 deletions(-) (limited to 'tools') diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index df6809a76404..69c200e6e696 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -201,6 +201,8 @@ enum bpf_attach_type { BPF_CGROUP_GETSOCKOPT, BPF_CGROUP_SETSOCKOPT, BPF_TRACE_RAW_TP, + BPF_TRACE_FENTRY, + BPF_TRACE_FEXIT, __MAX_BPF_ATTACH_TYPE }; diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 96ef18cfeffb..98ee033e021f 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -3856,7 +3856,8 @@ bpf_object__load_progs(struct bpf_object *obj, int log_level) return 0; } -static int libbpf_attach_btf_id_by_name(const char *name, __u32 *btf_id); +static int libbpf_attach_btf_id_by_name(const char *name, + enum bpf_attach_type attach_type); static struct bpf_object * __bpf_object__open(const char *path, const void *obj_buf, size_t obj_buf_sz, @@ -3910,7 +3911,6 @@ __bpf_object__open(const char *path, const void *obj_buf, size_t obj_buf_sz, bpf_object__for_each_program(prog, obj) { enum bpf_prog_type prog_type; enum bpf_attach_type attach_type; - __u32 btf_id; err = libbpf_prog_type_by_name(prog->section_name, &prog_type, &attach_type); @@ -3923,10 +3923,11 @@ __bpf_object__open(const char *path, const void *obj_buf, size_t obj_buf_sz, bpf_program__set_type(prog, prog_type); bpf_program__set_expected_attach_type(prog, attach_type); if (prog_type == BPF_PROG_TYPE_TRACING) { - err = libbpf_attach_btf_id_by_name(prog->section_name, &btf_id); - if (err) + err = libbpf_attach_btf_id_by_name(prog->section_name, + attach_type); + if (err <= 0) goto out; - prog->attach_btf_id = btf_id; + prog->attach_btf_id = err; } } @@ -4935,6 +4936,10 @@ static const struct { BPF_PROG_SEC("raw_tp/", BPF_PROG_TYPE_RAW_TRACEPOINT), BPF_PROG_BTF("tp_btf/", BPF_PROG_TYPE_TRACING, BPF_TRACE_RAW_TP), + BPF_PROG_BTF("fentry/", BPF_PROG_TYPE_TRACING, + BPF_TRACE_FENTRY), + BPF_PROG_BTF("fexit/", BPF_PROG_TYPE_TRACING, + BPF_TRACE_FEXIT), BPF_PROG_SEC("xdp", BPF_PROG_TYPE_XDP), BPF_PROG_SEC("perf_event", BPF_PROG_TYPE_PERF_EVENT), BPF_PROG_SEC("lwt_in", BPF_PROG_TYPE_LWT_IN), @@ -5052,43 +5057,56 @@ int libbpf_prog_type_by_name(const char *name, enum bpf_prog_type *prog_type, } #define BTF_PREFIX "btf_trace_" -static int libbpf_attach_btf_id_by_name(const char *name, __u32 *btf_id) +int libbpf_find_vmlinux_btf_id(const char *name, + enum bpf_attach_type attach_type) { struct btf *btf = bpf_core_find_kernel_btf(); - char raw_tp_btf_name[128] = BTF_PREFIX; - char *dst = raw_tp_btf_name + sizeof(BTF_PREFIX) - 1; - int ret, i, err = -EINVAL; + 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; 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; +} + +static int libbpf_attach_btf_id_by_name(const char *name, + enum bpf_attach_type attach_type) +{ + int i, err; + if (!name) - goto out; + return -EINVAL; for (i = 0; i < ARRAY_SIZE(section_names); i++) { if (!section_names[i].is_attach_btf) continue; if (strncmp(name, section_names[i].sec, section_names[i].len)) continue; - /* prepend "btf_trace_" prefix per kernel convention */ - strncat(dst, name + section_names[i].len, - sizeof(raw_tp_btf_name) - sizeof(BTF_PREFIX)); - ret = btf__find_by_name(btf, raw_tp_btf_name); - if (ret <= 0) { - pr_warn("%s is not found in vmlinux BTF\n", dst); - goto out; - } - *btf_id = ret; - err = 0; - goto out; + err = libbpf_find_vmlinux_btf_id(name + section_names[i].len, + attach_type); + if (err <= 0) + pr_warn("%s is not found in vmlinux BTF\n", name); + return err; } pr_warn("failed to identify btf_id based on ELF section name '%s'\n", name); - err = -ESRCH; -out: - btf__free(btf); - return err; + return -ESRCH; } int libbpf_attach_type_by_name(const char *name, @@ -5716,6 +5734,37 @@ struct bpf_link *bpf_program__attach_raw_tracepoint(struct bpf_program *prog, return (struct bpf_link *)link; } +struct bpf_link *bpf_program__attach_trace(struct bpf_program *prog) +{ + char errmsg[STRERR_BUFSIZE]; + struct bpf_link_fd *link; + int prog_fd, pfd; + + prog_fd = bpf_program__fd(prog); + if (prog_fd < 0) { + pr_warn("program '%s': can't attach before loaded\n", + bpf_program__title(prog, false)); + return ERR_PTR(-EINVAL); + } + + link = malloc(sizeof(*link)); + if (!link) + return ERR_PTR(-ENOMEM); + link->link.destroy = &bpf_link__destroy_fd; + + pfd = bpf_raw_tracepoint_open(NULL, prog_fd); + if (pfd < 0) { + pfd = -errno; + free(link); + pr_warn("program '%s': failed to attach to trace: %s\n", + bpf_program__title(prog, false), + libbpf_strerror_r(pfd, errmsg, sizeof(errmsg))); + return ERR_PTR(pfd); + } + link->fd = pfd; + return (struct bpf_link *)link; +} + enum bpf_perf_event_ret bpf_perf_event_read_simple(void *mmap_mem, size_t mmap_size, size_t page_size, void **copy_mem, size_t *copy_size, diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h index 5aa27caad6c2..fbff419f6daf 100644 --- a/tools/lib/bpf/libbpf.h +++ b/tools/lib/bpf/libbpf.h @@ -188,6 +188,8 @@ libbpf_prog_type_by_name(const char *name, enum bpf_prog_type *prog_type, enum bpf_attach_type *expected_attach_type); LIBBPF_API int libbpf_attach_type_by_name(const char *name, enum bpf_attach_type *attach_type); +LIBBPF_API int libbpf_find_vmlinux_btf_id(const char *name, + enum bpf_attach_type attach_type); /* Accessors of bpf_program */ struct bpf_program; @@ -251,6 +253,8 @@ LIBBPF_API struct bpf_link * bpf_program__attach_raw_tracepoint(struct bpf_program *prog, const char *tp_name); +LIBBPF_API struct bpf_link * +bpf_program__attach_trace(struct bpf_program *prog); struct bpf_insn; /* diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map index 420e69bfe699..8ddc2c40e482 100644 --- a/tools/lib/bpf/libbpf.map +++ b/tools/lib/bpf/libbpf.map @@ -199,10 +199,12 @@ LIBBPF_0.0.6 { bpf_map__set_pin_path; bpf_object__open_file; bpf_object__open_mem; + bpf_program__attach_trace; bpf_program__get_expected_attach_type; bpf_program__get_type; bpf_program__is_tracing; bpf_program__set_tracing; bpf_program__size; btf__find_by_name_kind; + libbpf_find_vmlinux_btf_id; } LIBBPF_0.0.5; -- cgit v1.2.3-59-g8ed1b