From: Andrii Nakryiko <andriin@fb.com>
To: <andrii.nakryiko@gmail.com>, <ast@fb.com>, <daniel@iogearbox.net>,
<netdev@vger.kernel.org>, <bpf@vger.kernel.org>,
<sdf@fomichev.me>, <kernel-team@fb.com>
Cc: Andrii Nakryiko <andriin@fb.com>
Subject: [PATCH v3 bpf-next 5/9] libbpf: add tracepoint attach API
Date: Thu, 27 Jun 2019 22:52:59 -0700 [thread overview]
Message-ID: <20190628055303.1249758-6-andriin@fb.com> (raw)
In-Reply-To: <20190628055303.1249758-1-andriin@fb.com>
Allow attaching BPF programs to kernel tracepoint BPF hooks specified by
category and name.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
---
tools/lib/bpf/libbpf.c | 78 ++++++++++++++++++++++++++++++++++++++++
tools/lib/bpf/libbpf.h | 4 +++
tools/lib/bpf/libbpf.map | 1 +
3 files changed, 83 insertions(+)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 65d2fef41003..76d1599a7d56 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -4229,6 +4229,84 @@ struct bpf_link *bpf_program__attach_uprobe(struct bpf_program *prog,
return link;
}
+static int determine_tracepoint_id(const char* tp_category, const char* tp_name)
+{
+ char file[PATH_MAX];
+ int ret;
+
+ ret = snprintf(file, sizeof(file),
+ "/sys/kernel/debug/tracing/events/%s/%s/id",
+ tp_category, tp_name);
+ if (ret < 0)
+ return -errno;
+ if (ret >= sizeof(file)) {
+ pr_debug("tracepoint %s/%s path is too long\n",
+ tp_category, tp_name);
+ return -E2BIG;
+ }
+ return parse_uint_from_file(file);
+}
+
+static int perf_event_open_tracepoint(const char* tp_category,
+ const char* tp_name)
+{
+ struct perf_event_attr attr = {};
+ char errmsg[STRERR_BUFSIZE];
+ int tp_id, pfd, err;
+
+ tp_id = determine_tracepoint_id(tp_category, tp_name);
+ if (tp_id < 0){
+ pr_warning("failed to determine tracepoint '%s/%s' perf ID: %s\n",
+ tp_category, tp_name,
+ libbpf_strerror_r(tp_id, errmsg, sizeof(errmsg)));
+ return tp_id;
+ }
+
+ attr.type = PERF_TYPE_TRACEPOINT;
+ attr.size = sizeof(attr);
+ attr.config = tp_id;
+
+ pfd = syscall( __NR_perf_event_open, &attr, -1 /* pid */, 0 /* cpu */,
+ -1 /* group_fd */, PERF_FLAG_FD_CLOEXEC);
+ if (pfd < 0) {
+ err = -errno;
+ pr_warning("tracepoint '%s/%s' perf_event_open() failed: %s\n",
+ tp_category, tp_name,
+ libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+ return err;
+ }
+ return pfd;
+}
+
+struct bpf_link *bpf_program__attach_tracepoint(struct bpf_program *prog,
+ const char *tp_category,
+ const char *tp_name)
+{
+ char errmsg[STRERR_BUFSIZE];
+ struct bpf_link *link;
+ int pfd, err;
+
+ pfd = perf_event_open_tracepoint(tp_category, tp_name);
+ if (pfd < 0) {
+ pr_warning("program '%s': failed to create tracepoint '%s/%s' perf event: %s\n",
+ bpf_program__title(prog, false),
+ tp_category, tp_name,
+ libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
+ return ERR_PTR(pfd);
+ }
+ link = bpf_program__attach_perf_event(prog, pfd);
+ if (IS_ERR(link)) {
+ close(pfd);
+ err = PTR_ERR(link);
+ pr_warning("program '%s': failed to attach to tracepoint '%s/%s': %s\n",
+ bpf_program__title(prog, false),
+ tp_category, tp_name,
+ libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+ return link;
+ }
+ return 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 bd767cc11967..60611f4b4e1d 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -178,6 +178,10 @@ LIBBPF_API struct bpf_link *
bpf_program__attach_uprobe(struct bpf_program *prog, bool retprobe,
pid_t pid, const char *binary_path,
size_t func_offset);
+LIBBPF_API struct bpf_link *
+bpf_program__attach_tracepoint(struct bpf_program *prog,
+ const char *tp_category,
+ const char *tp_name);
struct bpf_insn;
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index 57a40fb60718..3c618b75ef65 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -171,6 +171,7 @@ LIBBPF_0.0.4 {
bpf_object__load_xattr;
bpf_program__attach_kprobe;
bpf_program__attach_perf_event;
+ bpf_program__attach_tracepoint;
bpf_program__attach_uprobe;
btf_dump__dump_type;
btf_dump__free;
--
2.17.1
next prev parent reply other threads:[~2019-06-28 5:53 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-28 5:52 [PATCH v3 bpf-next 0/9] libbpf: add bpf_link and tracing attach APIs Andrii Nakryiko
2019-06-28 5:52 ` [PATCH v3 bpf-next 1/9] libbpf: make libbpf_strerror_r agnostic to sign of error Andrii Nakryiko
2019-06-28 19:34 ` Song Liu
2019-06-28 5:52 ` [PATCH v3 bpf-next 2/9] libbpf: introduce concept of bpf_link Andrii Nakryiko
2019-06-28 16:02 ` Stanislav Fomichev
2019-06-28 16:42 ` Andrii Nakryiko
2019-06-28 17:45 ` Stanislav Fomichev
2019-06-28 17:49 ` Alexei Starovoitov
2019-06-28 17:55 ` Stanislav Fomichev
2019-06-28 19:37 ` Song Liu
2019-06-28 5:52 ` [PATCH v3 bpf-next 3/9] libbpf: add ability to attach/detach BPF program to perf event Andrii Nakryiko
2019-06-28 16:04 ` Stanislav Fomichev
2019-06-28 16:50 ` Andrii Nakryiko
2019-06-28 17:54 ` Stanislav Fomichev
2019-06-28 17:59 ` Andrii Nakryiko
2019-06-28 18:00 ` Stanislav Fomichev
2019-06-28 18:04 ` Andrii Nakryiko
2019-06-28 18:14 ` Stanislav Fomichev
2019-06-28 18:15 ` Andrii Nakryiko
2019-06-28 18:05 ` Stanislav Fomichev
2019-06-28 5:52 ` [PATCH v3 bpf-next 4/9] libbpf: add kprobe/uprobe attach API Andrii Nakryiko
2019-06-28 19:46 ` Song Liu
2019-06-28 19:59 ` Andrii Nakryiko
2019-06-28 20:09 ` Song Liu
2019-06-28 20:34 ` Andrii Nakryiko
2019-06-28 5:52 ` Andrii Nakryiko [this message]
2019-06-28 19:50 ` [PATCH v3 bpf-next 5/9] libbpf: add tracepoint " Song Liu
2019-06-28 20:13 ` Song Liu
2019-06-28 5:53 ` [PATCH v3 bpf-next 6/9] libbpf: add raw " Andrii Nakryiko
2019-06-28 19:54 ` Song Liu
2019-06-28 5:53 ` [PATCH v3 bpf-next 7/9] selftests/bpf: switch test to new attach_perf_event API Andrii Nakryiko
2019-06-28 20:09 ` Song Liu
2019-06-28 5:53 ` [PATCH v3 bpf-next 8/9] selftests/bpf: add kprobe/uprobe selftests Andrii Nakryiko
2019-06-28 20:10 ` Song Liu
2019-06-28 5:53 ` [PATCH v3 bpf-next 9/9] selftests/bpf: convert existing tracepoint tests to new APIs Andrii Nakryiko
2019-06-28 20:13 ` Song Liu
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