[PATCH v6 bpf-next 0/5] libbpf: add perf buffer abstraction and API

[PATCH v6 bpf-next 0/5] libbpf: add perf buffer abstraction and API

[Andrii Nakryiko]

This patchset adds a high-level API for setting up and polling perf buffers
associated with BPF_MAP_TYPE_PERF_EVENT_ARRAY map. Details of APIs are
described in corresponding commit.

Patch #1 adds a set of APIs to set up and work with perf buffer.
Patch #2 enhances libbpf to support auto-setting PERF_EVENT_ARRAY map size.
Patch #3 adds test.
Patch #4 converts bpftool map event_pipe to new API.
Patch #5 updates README to mention perf_buffer_ prefix.

v5->v6:
- fix C99 for loop variable initialization usage (Yonghong);
v4->v5:
- initialize perf_buffer_raw_opts in bpftool map event_pipe (Jakub);
- add perf_buffer_ to README;
v3->v4:
- fixed bpftool event_pipe cmd error handling (Jakub);
v2->v3:
- added perf_buffer__new_raw for more low-level control;
- converted bpftool map event_pipe to new API (Daniel);
- fixed bug with error handling in create_maps (Song);
v1->v2:
- add auto-sizing of PERF_EVENT_ARRAY maps;

Andrii Nakryiko (5):
  libbpf: add perf buffer API
  libbpf: auto-set PERF_EVENT_ARRAY size to number of CPUs
  selftests/bpf: test perf buffer API
  tools/bpftool: switch map event_pipe to libbpf's perf_buffer
  libbpf: add perf_buffer_ prefix to README

 tools/bpf/bpftool/map_perf_ring.c             | 201 +++------
 tools/lib/bpf/README.rst                      |   3 +-
 tools/lib/bpf/libbpf.c                        | 397 +++++++++++++++++-
 tools/lib/bpf/libbpf.h                        |  49 +++
 tools/lib/bpf/libbpf.map                      |   4 +
 .../selftests/bpf/prog_tests/perf_buffer.c    |  94 +++++
 .../selftests/bpf/progs/test_perf_buffer.c    |  25 ++
 7 files changed, 628 insertions(+), 145 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/perf_buffer.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_perf_buffer.c

-- 
2.17.1

[PATCH v6 bpf-next 1/5] libbpf: add perf buffer API

[Andrii Nakryiko]

BPF_MAP_TYPE_PERF_EVENT_ARRAY map is often used to send data from BPF program
to user space for additional processing. libbpf already has very low-level API
to read single CPU perf buffer, bpf_perf_event_read_simple(), but it's hard to
use and requires a lot of code to set everything up. This patch adds
perf_buffer abstraction on top of it, abstracting setting up and polling
per-CPU logic into simple and convenient API, similar to what BCC provides.

perf_buffer__new() sets up per-CPU ring buffers and updates corresponding BPF
map entries. It accepts two user-provided callbacks: one for handling raw
samples and one for get notifications of lost samples due to buffer overflow.

perf_buffer__new_raw() is similar, but provides more control over how
perf events are set up (by accepting user-provided perf_event_attr), how
they are handled (perf_event_header pointer is passed directly to
user-provided callback), and on which CPUs ring buffers are created
(it's possible to provide a list of CPUs and corresponding map keys to
update). This API allows advanced users fuller control.

perf_buffer__poll() is used to fetch ring buffer data across all CPUs,
utilizing epoll instance.

perf_buffer__free() does corresponding clean up and unsets FDs from BPF map.

All APIs are not thread-safe. User should ensure proper locking/coordination if
used in multi-threaded set up.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
---
 tools/lib/bpf/libbpf.c   | 366 +++++++++++++++++++++++++++++++++++++++
 tools/lib/bpf/libbpf.h   |  49 ++++++
 tools/lib/bpf/libbpf.map |   4 +
 3 files changed, 419 insertions(+)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 2a08eb106221..ae569b50e2e0 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -32,7 +32,9 @@
 #include <linux/limits.h>
 #include <linux/perf_event.h>
 #include <linux/ring_buffer.h>
+#include <sys/epoll.h>
 #include <sys/ioctl.h>
+#include <sys/mman.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <sys/vfs.h>
@@ -4354,6 +4356,370 @@ bpf_perf_event_read_simple(void *mmap_mem, size_t mmap_size, size_t page_size,
 	return ret;
 }
 
+struct perf_buffer;
+
+struct perf_buffer_params {
+	struct perf_event_attr *attr;
+	/* if event_cb is specified, it takes precendence */
+	perf_buffer_event_fn event_cb;
+	/* sample_cb and lost_cb are higher-level common-case callbacks */
+	perf_buffer_sample_fn sample_cb;
+	perf_buffer_lost_fn lost_cb;
+	void *ctx;
+	int cpu_cnt;
+	int *cpus;
+	int *map_keys;
+};
+
+struct perf_cpu_buf {
+	struct perf_buffer *pb;
+	void *base; /* mmap()'ed memory */
+	void *buf; /* for reconstructing segmented data */
+	size_t buf_size;
+	int fd;
+	int cpu;
+	int map_key;
+};
+
+struct perf_buffer {
+	perf_buffer_event_fn event_cb;
+	perf_buffer_sample_fn sample_cb;
+	perf_buffer_lost_fn lost_cb;
+	void *ctx; /* passed into callbacks */
+
+	size_t page_size;
+	size_t mmap_size;
+	struct perf_cpu_buf **cpu_bufs;
+	struct epoll_event *events;
+	int cpu_cnt;
+	int epoll_fd; /* perf event FD */
+	int map_fd; /* BPF_MAP_TYPE_PERF_EVENT_ARRAY BPF map FD */
+};
+
+static void perf_buffer__free_cpu_buf(struct perf_buffer *pb,
+				      struct perf_cpu_buf *cpu_buf)
+{
+	if (!cpu_buf)
+		return;
+	if (cpu_buf->base &&
+	    munmap(cpu_buf->base, pb->mmap_size + pb->page_size))
+		pr_warning("failed to munmap cpu_buf #%d\n", cpu_buf->cpu);
+	if (cpu_buf->fd >= 0) {
+		ioctl(cpu_buf->fd, PERF_EVENT_IOC_DISABLE, 0);
+		close(cpu_buf->fd);
+	}
+	free(cpu_buf->buf);
+	free(cpu_buf);
+}
+
+void perf_buffer__free(struct perf_buffer *pb)
+{
+	int i;
+
+	if (!pb)
+		return;
+	if (pb->cpu_bufs) {
+		for (i = 0; i < pb->cpu_cnt && pb->cpu_bufs[i]; i++) {
+			struct perf_cpu_buf *cpu_buf = pb->cpu_bufs[i];
+
+			bpf_map_delete_elem(pb->map_fd, &cpu_buf->map_key);
+			perf_buffer__free_cpu_buf(pb, cpu_buf);
+		}
+		free(pb->cpu_bufs);
+	}
+	if (pb->epoll_fd >= 0)
+		close(pb->epoll_fd);
+	free(pb->events);
+	free(pb);
+}
+
+static struct perf_cpu_buf *
+perf_buffer__open_cpu_buf(struct perf_buffer *pb, struct perf_event_attr *attr,
+			  int cpu, int map_key)
+{
+	struct perf_cpu_buf *cpu_buf;
+	char msg[STRERR_BUFSIZE];
+	int err;
+
+	cpu_buf = calloc(1, sizeof(*cpu_buf));
+	if (!cpu_buf)
+		return ERR_PTR(-ENOMEM);
+
+	cpu_buf->pb = pb;
+	cpu_buf->cpu = cpu;
+	cpu_buf->map_key = map_key;
+
+	cpu_buf->fd = syscall(__NR_perf_event_open, attr, -1 /* pid */, cpu,
+			      -1, PERF_FLAG_FD_CLOEXEC);
+	if (cpu_buf->fd < 0) {
+		err = -errno;
+		pr_warning("failed to open perf buffer event on cpu #%d: %s\n",
+			   cpu, libbpf_strerror_r(err, msg, sizeof(msg)));
+		goto error;
+	}
+
+	cpu_buf->base = mmap(NULL, pb->mmap_size + pb->page_size,
+			     PROT_READ | PROT_WRITE, MAP_SHARED,
+			     cpu_buf->fd, 0);
+	if (cpu_buf->base == MAP_FAILED) {
+		cpu_buf->base = NULL;
+		err = -errno;
+		pr_warning("failed to mmap perf buffer on cpu #%d: %s\n",
+			   cpu, libbpf_strerror_r(err, msg, sizeof(msg)));
+		goto error;
+	}
+
+	if (ioctl(cpu_buf->fd, PERF_EVENT_IOC_ENABLE, 0) < 0) {
+		err = -errno;
+		pr_warning("failed to enable perf buffer event on cpu #%d: %s\n",
+			   cpu, libbpf_strerror_r(err, msg, sizeof(msg)));
+		goto error;
+	}
+
+	return cpu_buf;
+
+error:
+	perf_buffer__free_cpu_buf(pb, cpu_buf);
+	return (struct perf_cpu_buf *)ERR_PTR(err);
+}
+
+static struct perf_buffer *__perf_buffer__new(int map_fd, size_t page_cnt,
+					      struct perf_buffer_params *p);
+
+struct perf_buffer *perf_buffer__new(int map_fd, size_t page_cnt,
+				     const struct perf_buffer_opts *opts)
+{
+	struct perf_buffer_params p = {};
+	struct perf_event_attr attr = {
+		.config = PERF_COUNT_SW_BPF_OUTPUT,
+		.type = PERF_TYPE_SOFTWARE,
+		.sample_type = PERF_SAMPLE_RAW,
+		.sample_period = 1,
+		.wakeup_events = 1,
+	};
+
+	p.attr = &attr;
+	p.sample_cb = opts ? opts->sample_cb : NULL;
+	p.lost_cb = opts ? opts->lost_cb : NULL;
+	p.ctx = opts ? opts->ctx : NULL;
+
+	return __perf_buffer__new(map_fd, page_cnt, &p);
+}
+
+struct perf_buffer *
+perf_buffer__new_raw(int map_fd, size_t page_cnt,
+		     const struct perf_buffer_raw_opts *opts)
+{
+	struct perf_buffer_params p = {};
+
+	p.attr = opts->attr;
+	p.event_cb = opts->event_cb;
+	p.ctx = opts->ctx;
+	p.cpu_cnt = opts->cpu_cnt;
+	p.cpus = opts->cpus;
+	p.map_keys = opts->map_keys;
+
+	return __perf_buffer__new(map_fd, page_cnt, &p);
+}
+
+static struct perf_buffer *__perf_buffer__new(int map_fd, size_t page_cnt,
+					      struct perf_buffer_params *p)
+{
+	struct bpf_map_info map = {};
+	char msg[STRERR_BUFSIZE];
+	struct perf_buffer *pb;
+	__u32 map_info_len;
+	int err, i;
+
+	if (page_cnt & (page_cnt - 1)) {
+		pr_warning("page count should be power of two, but is %zu\n",
+			   page_cnt);
+		return ERR_PTR(-EINVAL);
+	}
+
+	map_info_len = sizeof(map);
+	err = bpf_obj_get_info_by_fd(map_fd, &map, &map_info_len);
+	if (err) {
+		err = -errno;
+		pr_warning("failed to get map info for map FD %d: %s\n",
+			   map_fd, libbpf_strerror_r(err, msg, sizeof(msg)));
+		return ERR_PTR(err);
+	}
+
+	if (map.type != BPF_MAP_TYPE_PERF_EVENT_ARRAY) {
+		pr_warning("map '%s' should be BPF_MAP_TYPE_PERF_EVENT_ARRAY\n",
+			   map.name);
+		return ERR_PTR(-EINVAL);
+	}
+
+	pb = calloc(1, sizeof(*pb));
+	if (!pb)
+		return ERR_PTR(-ENOMEM);
+
+	pb->event_cb = p->event_cb;
+	pb->sample_cb = p->sample_cb;
+	pb->lost_cb = p->lost_cb;
+	pb->ctx = p->ctx;
+
+	pb->page_size = getpagesize();
+	pb->mmap_size = pb->page_size * page_cnt;
+	pb->map_fd = map_fd;
+
+	pb->epoll_fd = epoll_create1(EPOLL_CLOEXEC);
+	if (pb->epoll_fd < 0) {
+		err = -errno;
+		pr_warning("failed to create epoll instance: %s\n",
+			   libbpf_strerror_r(err, msg, sizeof(msg)));
+		goto error;
+	}
+
+	if (p->cpu_cnt > 0) {
+		pb->cpu_cnt = p->cpu_cnt;
+	} else {
+		pb->cpu_cnt = libbpf_num_possible_cpus();
+		if (pb->cpu_cnt < 0) {
+			err = pb->cpu_cnt;
+			goto error;
+		}
+		if (map.max_entries < pb->cpu_cnt)
+			pb->cpu_cnt = map.max_entries;
+	}
+
+	pb->events = calloc(pb->cpu_cnt, sizeof(*pb->events));
+	if (!pb->events) {
+		err = -ENOMEM;
+		pr_warning("failed to allocate events: out of memory\n");
+		goto error;
+	}
+	pb->cpu_bufs = calloc(pb->cpu_cnt, sizeof(*pb->cpu_bufs));
+	if (!pb->cpu_bufs) {
+		err = -ENOMEM;
+		pr_warning("failed to allocate buffers: out of memory\n");
+		goto error;
+	}
+
+	for (i = 0; i < pb->cpu_cnt; i++) {
+		struct perf_cpu_buf *cpu_buf;
+		int cpu, map_key;
+
+		cpu = p->cpu_cnt > 0 ? p->cpus[i] : i;
+		map_key = p->cpu_cnt > 0 ? p->map_keys[i] : i;
+
+		cpu_buf = perf_buffer__open_cpu_buf(pb, p->attr, cpu, map_key);
+		if (IS_ERR(cpu_buf)) {
+			err = PTR_ERR(cpu_buf);
+			goto error;
+		}
+
+		pb->cpu_bufs[i] = cpu_buf;
+
+		err = bpf_map_update_elem(pb->map_fd, &map_key,
+					  &cpu_buf->fd, 0);
+		if (err) {
+			err = -errno;
+			pr_warning("failed to set cpu #%d, key %d -> perf FD %d: %s\n",
+				   cpu, map_key, cpu_buf->fd,
+				   libbpf_strerror_r(err, msg, sizeof(msg)));
+			goto error;
+		}
+
+		pb->events[i].events = EPOLLIN;
+		pb->events[i].data.ptr = cpu_buf;
+		if (epoll_ctl(pb->epoll_fd, EPOLL_CTL_ADD, cpu_buf->fd,
+			      &pb->events[i]) < 0) {
+			err = -errno;
+			pr_warning("failed to epoll_ctl cpu #%d perf FD %d: %s\n",
+				   cpu, cpu_buf->fd,
+				   libbpf_strerror_r(err, msg, sizeof(msg)));
+			goto error;
+		}
+	}
+
+	return pb;
+
+error:
+	if (pb)
+		perf_buffer__free(pb);
+	return ERR_PTR(err);
+}
+
+struct perf_sample_raw {
+	struct perf_event_header header;
+	uint32_t size;
+	char data[0];
+};
+
+struct perf_sample_lost {
+	struct perf_event_header header;
+	uint64_t id;
+	uint64_t lost;
+	uint64_t sample_id;
+};
+
+static enum bpf_perf_event_ret
+perf_buffer__process_record(struct perf_event_header *e, void *ctx)
+{
+	struct perf_cpu_buf *cpu_buf = ctx;
+	struct perf_buffer *pb = cpu_buf->pb;
+	void *data = e;
+
+	/* user wants full control over parsing perf event */
+	if (pb->event_cb)
+		return pb->event_cb(pb->ctx, cpu_buf->cpu, e);
+
+	switch (e->type) {
+	case PERF_RECORD_SAMPLE: {
+		struct perf_sample_raw *s = data;
+
+		if (pb->sample_cb)
+			pb->sample_cb(pb->ctx, cpu_buf->cpu, s->data, s->size);
+		break;
+	}
+	case PERF_RECORD_LOST: {
+		struct perf_sample_lost *s = data;
+
+		if (pb->lost_cb)
+			pb->lost_cb(pb->ctx, cpu_buf->cpu, s->lost);
+		break;
+	}
+	default:
+		pr_warning("unknown perf sample type %d\n", e->type);
+		return LIBBPF_PERF_EVENT_ERROR;
+	}
+	return LIBBPF_PERF_EVENT_CONT;
+}
+
+static int perf_buffer__process_records(struct perf_buffer *pb,
+					struct perf_cpu_buf *cpu_buf)
+{
+	enum bpf_perf_event_ret ret;
+
+	ret = bpf_perf_event_read_simple(cpu_buf->base, pb->mmap_size,
+					 pb->page_size, &cpu_buf->buf,
+					 &cpu_buf->buf_size,
+					 perf_buffer__process_record, cpu_buf);
+	if (ret != LIBBPF_PERF_EVENT_CONT)
+		return ret;
+	return 0;
+}
+
+int perf_buffer__poll(struct perf_buffer *pb, int timeout_ms)
+{
+	int i, cnt, err;
+
+	cnt = epoll_wait(pb->epoll_fd, pb->events, pb->cpu_cnt, timeout_ms);
+	for (i = 0; i < cnt; i++) {
+		struct perf_cpu_buf *cpu_buf = pb->events[i].data.ptr;
+
+		err = perf_buffer__process_records(pb, cpu_buf);
+		if (err) {
+			pr_warning("error while processing records: %d\n", err);
+			return err;
+		}
+	}
+	return cnt < 0 ? -errno : cnt;
+}
+
 struct bpf_prog_info_array_desc {
 	int	array_offset;	/* e.g. offset of jited_prog_insns */
 	int	count_offset;	/* e.g. offset of jited_prog_len */
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index f55933784f95..5cbf459ece0b 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -358,6 +358,26 @@ LIBBPF_API int bpf_prog_load(const char *file, enum bpf_prog_type type,
 LIBBPF_API int bpf_set_link_xdp_fd(int ifindex, int fd, __u32 flags);
 LIBBPF_API int bpf_get_link_xdp_id(int ifindex, __u32 *prog_id, __u32 flags);
 
+struct perf_buffer;
+
+typedef void (*perf_buffer_sample_fn)(void *ctx, int cpu,
+				      void *data, __u32 size);
+typedef void (*perf_buffer_lost_fn)(void *ctx, int cpu, __u64 cnt);
+
+/* common use perf buffer options */
+struct perf_buffer_opts {
+	/* if specified, sample_cb is called for each sample */
+	perf_buffer_sample_fn sample_cb;
+	/* if specified, lost_cb is called for each batch of lost samples */
+	perf_buffer_lost_fn lost_cb;
+	/* ctx is provided to sample_cb and lost_cb */
+	void *ctx;
+};
+
+LIBBPF_API struct perf_buffer *
+perf_buffer__new(int map_fd, size_t page_cnt,
+		 const struct perf_buffer_opts *opts);
+
 enum bpf_perf_event_ret {
 	LIBBPF_PERF_EVENT_DONE	= 0,
 	LIBBPF_PERF_EVENT_ERROR	= -1,
@@ -365,6 +385,35 @@ enum bpf_perf_event_ret {
 };
 
 struct perf_event_header;
+
+typedef enum bpf_perf_event_ret
+(*perf_buffer_event_fn)(void *ctx, int cpu, struct perf_event_header *event);
+
+/* raw perf buffer options, giving most power and control */
+struct perf_buffer_raw_opts {
+	/* perf event attrs passed directly into perf_event_open() */
+	struct perf_event_attr *attr;
+	/* raw event callback */
+	perf_buffer_event_fn event_cb;
+	/* ctx is provided to event_cb */
+	void *ctx;
+	/* if cpu_cnt == 0, open all on all possible CPUs (up to the number of
+	 * max_entries of given PERF_EVENT_ARRAY map)
+	 */
+	int cpu_cnt;
+	/* if cpu_cnt > 0, cpus is an array of CPUs to open ring buffers on */
+	int *cpus;
+	/* if cpu_cnt > 0, map_keys specify map keys to set per-CPU FDs for */
+	int *map_keys;
+};
+
+LIBBPF_API struct perf_buffer *
+perf_buffer__new_raw(int map_fd, size_t page_cnt,
+		     const struct perf_buffer_raw_opts *opts);
+
+LIBBPF_API void perf_buffer__free(struct perf_buffer *pb);
+LIBBPF_API int perf_buffer__poll(struct perf_buffer *pb, int timeout_ms);
+
 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.map b/tools/lib/bpf/libbpf.map
index e6b7d4edbc93..f9d316e873d8 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -179,4 +179,8 @@ LIBBPF_0.0.4 {
 		btf_dump__new;
 		btf__parse_elf;
 		libbpf_num_possible_cpus;
+		perf_buffer__free;
+		perf_buffer__new;
+		perf_buffer__new_raw;
+		perf_buffer__poll;
 } LIBBPF_0.0.3;
-- 
2.17.1

[PATCH v6 bpf-next 2/5] libbpf: auto-set PERF_EVENT_ARRAY size to number of CPUs

[Andrii Nakryiko]

For BPF_MAP_TYPE_PERF_EVENT_ARRAY typically correct size is number of
possible CPUs. This is impossible to specify at compilation time. This
change adds automatic setting of PERF_EVENT_ARRAY size to number of
system CPUs, unless non-zero size is specified explicitly. This allows
to adjust size for advanced specific cases, while providing convenient
and logical defaults.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Song Liu <songliubraving@fb.com>
---
 tools/lib/bpf/libbpf.c | 31 ++++++++++++++++++++++++-------
 1 file changed, 24 insertions(+), 7 deletions(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index ae569b50e2e0..ed07789b3e62 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -2116,6 +2116,7 @@ static int
 bpf_object__create_maps(struct bpf_object *obj)
 {
 	struct bpf_create_map_attr create_attr = {};
+	int nr_cpus = 0;
 	unsigned int i;
 	int err;
 
@@ -2138,7 +2139,22 @@ bpf_object__create_maps(struct bpf_object *obj)
 		create_attr.map_flags = def->map_flags;
 		create_attr.key_size = def->key_size;
 		create_attr.value_size = def->value_size;
-		create_attr.max_entries = def->max_entries;
+		if (def->type == BPF_MAP_TYPE_PERF_EVENT_ARRAY &&
+		    !def->max_entries) {
+			if (!nr_cpus)
+				nr_cpus = libbpf_num_possible_cpus();
+			if (nr_cpus < 0) {
+				pr_warning("failed to determine number of system CPUs: %d\n",
+					   nr_cpus);
+				err = nr_cpus;
+				goto err_out;
+			}
+			pr_debug("map '%s': setting size to %d\n",
+				 map->name, nr_cpus);
+			create_attr.max_entries = nr_cpus;
+		} else {
+			create_attr.max_entries = def->max_entries;
+		}
 		create_attr.btf_fd = 0;
 		create_attr.btf_key_type_id = 0;
 		create_attr.btf_value_type_id = 0;
@@ -2155,9 +2171,10 @@ bpf_object__create_maps(struct bpf_object *obj)
 		*pfd = bpf_create_map_xattr(&create_attr);
 		if (*pfd < 0 && (create_attr.btf_key_type_id ||
 				 create_attr.btf_value_type_id)) {
-			cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
+			err = -errno;
+			cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg));
 			pr_warning("Error in bpf_create_map_xattr(%s):%s(%d). Retrying without BTF.\n",
-				   map->name, cp, errno);
+				   map->name, cp, err);
 			create_attr.btf_fd = 0;
 			create_attr.btf_key_type_id = 0;
 			create_attr.btf_value_type_id = 0;
@@ -2169,11 +2186,11 @@ bpf_object__create_maps(struct bpf_object *obj)
 		if (*pfd < 0) {
 			size_t j;
 
-			err = *pfd;
+			err = -errno;
 err_out:
-			cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
-			pr_warning("failed to create map (name: '%s'): %s\n",
-				   map->name, cp);
+			cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg));
+			pr_warning("failed to create map (name: '%s'): %s(%d)\n",
+				   map->name, cp, err);
 			for (j = 0; j < i; j++)
 				zclose(obj->maps[j].fd);
 			return err;
-- 
2.17.1

[PATCH v6 bpf-next 3/5] selftests/bpf: test perf buffer API

[Andrii Nakryiko]

Add test verifying perf buffer API functionality.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Song Liu <songliubraving@fb.com>
---
 .../selftests/bpf/prog_tests/perf_buffer.c    | 94 +++++++++++++++++++
 .../selftests/bpf/progs/test_perf_buffer.c    | 25 +++++
 2 files changed, 119 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/perf_buffer.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_perf_buffer.c

diff --git a/tools/testing/selftests/bpf/prog_tests/perf_buffer.c b/tools/testing/selftests/bpf/prog_tests/perf_buffer.c
new file mode 100644
index 000000000000..64556ab0d1a9
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/perf_buffer.c
@@ -0,0 +1,94 @@
+// SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE
+#include <pthread.h>
+#include <sched.h>
+#include <sys/socket.h>
+#include <test_progs.h>
+
+static void on_sample(void *ctx, int cpu, void *data, __u32 size)
+{
+	int cpu_data = *(int *)data, duration = 0;
+	cpu_set_t *cpu_seen = ctx;
+
+	if (cpu_data != cpu)
+		CHECK(cpu_data != cpu, "check_cpu_data",
+		      "cpu_data %d != cpu %d\n", cpu_data, cpu);
+
+	CPU_SET(cpu, cpu_seen);
+}
+
+void test_perf_buffer(void)
+{
+	int err, prog_fd, nr_cpus, i, duration = 0;
+	const char *prog_name = "kprobe/sys_nanosleep";
+	const char *file = "./test_perf_buffer.o";
+	struct perf_buffer_opts pb_opts = {};
+	struct bpf_map *perf_buf_map;
+	cpu_set_t cpu_set, cpu_seen;
+	struct bpf_program *prog;
+	struct bpf_object *obj;
+	struct perf_buffer *pb;
+	struct bpf_link *link;
+
+	nr_cpus = libbpf_num_possible_cpus();
+	if (CHECK(nr_cpus < 0, "nr_cpus", "err %d\n", nr_cpus))
+		return;
+
+	/* load program */
+	err = bpf_prog_load(file, BPF_PROG_TYPE_KPROBE, &obj, &prog_fd);
+	if (CHECK(err, "obj_load", "err %d errno %d\n", err, errno))
+		return;
+
+	prog = bpf_object__find_program_by_title(obj, prog_name);
+	if (CHECK(!prog, "find_probe", "prog '%s' not found\n", prog_name))
+		goto out_close;
+
+	/* load map */
+	perf_buf_map = bpf_object__find_map_by_name(obj, "perf_buf_map");
+	if (CHECK(!perf_buf_map, "find_perf_buf_map", "not found\n"))
+		goto out_close;
+
+	/* attach kprobe */
+	link = bpf_program__attach_kprobe(prog, false /* retprobe */,
+					      "sys_nanosleep");
+	if (CHECK(IS_ERR(link), "attach_kprobe", "err %ld\n", PTR_ERR(link)))
+		goto out_close;
+
+	/* set up perf buffer */
+	pb_opts.sample_cb = on_sample;
+	pb_opts.ctx = &cpu_seen;
+	pb = perf_buffer__new(bpf_map__fd(perf_buf_map), 1, &pb_opts);
+	if (CHECK(IS_ERR(pb), "perf_buf__new", "err %ld\n", PTR_ERR(pb)))
+		goto out_detach;
+
+	/* trigger kprobe on every CPU */
+	CPU_ZERO(&cpu_seen);
+	for (i = 0; i < nr_cpus; i++) {
+		CPU_ZERO(&cpu_set);
+		CPU_SET(i, &cpu_set);
+
+		err = pthread_setaffinity_np(pthread_self(), sizeof(cpu_set),
+					     &cpu_set);
+		if (err && CHECK(err, "set_affinity", "cpu #%d, err %d\n",
+				 i, err))
+			goto out_detach;
+
+		usleep(1);
+	}
+
+	/* read perf buffer */
+	err = perf_buffer__poll(pb, 100);
+	if (CHECK(err < 0, "perf_buffer__poll", "err %d\n", err))
+		goto out_free_pb;
+
+	if (CHECK(CPU_COUNT(&cpu_seen) != nr_cpus, "seen_cpu_cnt",
+		  "expect %d, seen %d\n", nr_cpus, CPU_COUNT(&cpu_seen)))
+		goto out_free_pb;
+
+out_free_pb:
+	perf_buffer__free(pb);
+out_detach:
+	bpf_link__destroy(link);
+out_close:
+	bpf_object__close(obj);
+}
diff --git a/tools/testing/selftests/bpf/progs/test_perf_buffer.c b/tools/testing/selftests/bpf/progs/test_perf_buffer.c
new file mode 100644
index 000000000000..876c27deb65a
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_perf_buffer.c
@@ -0,0 +1,25 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2019 Facebook
+
+#include <linux/ptrace.h>
+#include <linux/bpf.h>
+#include "bpf_helpers.h"
+
+struct {
+	__uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
+	__uint(key_size, sizeof(int));
+	__uint(value_size, sizeof(int));
+} perf_buf_map SEC(".maps");
+
+SEC("kprobe/sys_nanosleep")
+int handle_sys_nanosleep_entry(struct pt_regs *ctx)
+{
+	int cpu = bpf_get_smp_processor_id();
+
+	bpf_perf_event_output(ctx, &perf_buf_map, BPF_F_CURRENT_CPU,
+			      &cpu, sizeof(cpu));
+	return 0;
+}
+
+char _license[] SEC("license") = "GPL";
+__u32 _version SEC("version") = 1;
-- 
2.17.1

[PATCH v6 bpf-next 4/5] tools/bpftool: switch map event_pipe to libbpf's perf_buffer

[Andrii Nakryiko]

Switch event_pipe implementation to rely on new libbpf perf buffer API
(it's raw low-level variant).

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
---
 tools/bpf/bpftool/map_perf_ring.c | 201 ++++++++++--------------------
 1 file changed, 64 insertions(+), 137 deletions(-)

diff --git a/tools/bpf/bpftool/map_perf_ring.c b/tools/bpf/bpftool/map_perf_ring.c
index 0507dfaf7a8f..3f108ab17797 100644
--- a/tools/bpf/bpftool/map_perf_ring.c
+++ b/tools/bpf/bpftool/map_perf_ring.c
@@ -28,7 +28,7 @@
 
 #define MMAP_PAGE_CNT	16
 
-static bool stop;
+static volatile bool stop;
 
 struct event_ring_info {
 	int fd;
@@ -44,32 +44,44 @@ struct perf_event_sample {
 	unsigned char data[];
 };
 
+struct perf_event_lost {
+	struct perf_event_header header;
+	__u64 id;
+	__u64 lost;
+};
+
 static void int_exit(int signo)
 {
 	fprintf(stderr, "Stopping...\n");
 	stop = true;
 }
 
+struct event_pipe_ctx {
+	bool all_cpus;
+	int cpu;
+	int idx;
+};
+
 static enum bpf_perf_event_ret
-print_bpf_output(struct perf_event_header *event, void *private_data)
+print_bpf_output(void *private_data, int cpu, struct perf_event_header *event)
 {
-	struct perf_event_sample *e = container_of(event, struct perf_event_sample,
+	struct perf_event_sample *e = container_of(event,
+						   struct perf_event_sample,
 						   header);
-	struct event_ring_info *ring = private_data;
-	struct {
-		struct perf_event_header header;
-		__u64 id;
-		__u64 lost;
-	} *lost = (typeof(lost))event;
+	struct perf_event_lost *lost = container_of(event,
+						    struct perf_event_lost,
+						    header);
+	struct event_pipe_ctx *ctx = private_data;
+	int idx = ctx->all_cpus ? cpu : ctx->idx;
 
 	if (json_output) {
 		jsonw_start_object(json_wtr);
 		jsonw_name(json_wtr, "type");
 		jsonw_uint(json_wtr, e->header.type);
 		jsonw_name(json_wtr, "cpu");
-		jsonw_uint(json_wtr, ring->cpu);
+		jsonw_uint(json_wtr, cpu);
 		jsonw_name(json_wtr, "index");
-		jsonw_uint(json_wtr, ring->key);
+		jsonw_uint(json_wtr, idx);
 		if (e->header.type == PERF_RECORD_SAMPLE) {
 			jsonw_name(json_wtr, "timestamp");
 			jsonw_uint(json_wtr, e->time);
@@ -89,7 +101,7 @@ print_bpf_output(struct perf_event_header *event, void *private_data)
 		if (e->header.type == PERF_RECORD_SAMPLE) {
 			printf("== @%lld.%09lld CPU: %d index: %d =====\n",
 			       e->time / 1000000000ULL, e->time % 1000000000ULL,
-			       ring->cpu, ring->key);
+			       cpu, idx);
 			fprint_hex(stdout, e->data, e->size, " ");
 			printf("\n");
 		} else if (e->header.type == PERF_RECORD_LOST) {
@@ -103,87 +115,25 @@ print_bpf_output(struct perf_event_header *event, void *private_data)
 	return LIBBPF_PERF_EVENT_CONT;
 }
 
-static void
-perf_event_read(struct event_ring_info *ring, void **buf, size_t *buf_len)
-{
-	enum bpf_perf_event_ret ret;
-
-	ret = bpf_perf_event_read_simple(ring->mem,
-					 MMAP_PAGE_CNT * get_page_size(),
-					 get_page_size(), buf, buf_len,
-					 print_bpf_output, ring);
-	if (ret != LIBBPF_PERF_EVENT_CONT) {
-		fprintf(stderr, "perf read loop failed with %d\n", ret);
-		stop = true;
-	}
-}
-
-static int perf_mmap_size(void)
-{
-	return get_page_size() * (MMAP_PAGE_CNT + 1);
-}
-
-static void *perf_event_mmap(int fd)
-{
-	int mmap_size = perf_mmap_size();
-	void *base;
-
-	base = mmap(NULL, mmap_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
-	if (base == MAP_FAILED) {
-		p_err("event mmap failed: %s\n", strerror(errno));
-		return NULL;
-	}
-
-	return base;
-}
-
-static void perf_event_unmap(void *mem)
-{
-	if (munmap(mem, perf_mmap_size()))
-		fprintf(stderr, "Can't unmap ring memory!\n");
-}
-
-static int bpf_perf_event_open(int map_fd, int key, int cpu)
+int do_event_pipe(int argc, char **argv)
 {
-	struct perf_event_attr attr = {
+	struct perf_event_attr perf_attr = {
 		.sample_type = PERF_SAMPLE_RAW | PERF_SAMPLE_TIME,
 		.type = PERF_TYPE_SOFTWARE,
 		.config = PERF_COUNT_SW_BPF_OUTPUT,
+		.sample_period = 1,
+		.wakeup_events = 1,
 	};
-	int pmu_fd;
-
-	pmu_fd = sys_perf_event_open(&attr, -1, cpu, -1, 0);
-	if (pmu_fd < 0) {
-		p_err("failed to open perf event %d for CPU %d", key, cpu);
-		return -1;
-	}
-
-	if (bpf_map_update_elem(map_fd, &key, &pmu_fd, BPF_ANY)) {
-		p_err("failed to update map for event %d for CPU %d", key, cpu);
-		goto err_close;
-	}
-	if (ioctl(pmu_fd, PERF_EVENT_IOC_ENABLE, 0)) {
-		p_err("failed to enable event %d for CPU %d", key, cpu);
-		goto err_close;
-	}
-
-	return pmu_fd;
-
-err_close:
-	close(pmu_fd);
-	return -1;
-}
-
-int do_event_pipe(int argc, char **argv)
-{
-	int i, nfds, map_fd, index = -1, cpu = -1;
 	struct bpf_map_info map_info = {};
-	struct event_ring_info *rings;
-	size_t tmp_buf_sz = 0;
-	void *tmp_buf = NULL;
-	struct pollfd *pfds;
+	struct perf_buffer_raw_opts opts = {};
+	struct event_pipe_ctx ctx = {
+		.all_cpus = true,
+		.cpu = -1,
+		.idx = -1,
+	};
+	struct perf_buffer *pb;
 	__u32 map_info_len;
-	bool do_all = true;
+	int err, map_fd;
 
 	map_info_len = sizeof(map_info);
 	map_fd = map_parse_fd_and_info(&argc, &argv, &map_info, &map_info_len);
@@ -205,7 +155,7 @@ int do_event_pipe(int argc, char **argv)
 			char *endptr;
 
 			NEXT_ARG();
-			cpu = strtoul(*argv, &endptr, 0);
+			ctx.cpu = strtoul(*argv, &endptr, 0);
 			if (*endptr) {
 				p_err("can't parse %s as CPU ID", **argv);
 				goto err_close_map;
@@ -216,7 +166,7 @@ int do_event_pipe(int argc, char **argv)
 			char *endptr;
 
 			NEXT_ARG();
-			index = strtoul(*argv, &endptr, 0);
+			ctx.idx = strtoul(*argv, &endptr, 0);
 			if (*endptr) {
 				p_err("can't parse %s as index", **argv);
 				goto err_close_map;
@@ -228,45 +178,32 @@ int do_event_pipe(int argc, char **argv)
 			goto err_close_map;
 		}
 
-		do_all = false;
+		ctx.all_cpus = false;
 	}
 
-	if (!do_all) {
-		if (index == -1 || cpu == -1) {
+	if (!ctx.all_cpus) {
+		if (ctx.idx == -1 || ctx.cpu == -1) {
 			p_err("cpu and index must be specified together");
 			goto err_close_map;
 		}
-
-		nfds = 1;
 	} else {
-		nfds = min(get_possible_cpus(), map_info.max_entries);
-		cpu = 0;
-		index = 0;
+		ctx.cpu = 0;
+		ctx.idx = 0;
 	}
 
-	rings = calloc(nfds, sizeof(rings[0]));
-	if (!rings)
+	opts.attr = &perf_attr;
+	opts.event_cb = print_bpf_output;
+	opts.ctx = &ctx;
+	opts.cpu_cnt = ctx.all_cpus ? 0 : 1;
+	opts.cpus = &ctx.cpu;
+	opts.map_keys = &ctx.idx;
+
+	pb = perf_buffer__new_raw(map_fd, MMAP_PAGE_CNT, &opts);
+	err = libbpf_get_error(pb);
+	if (err) {
+		p_err("failed to create perf buffer: %s (%d)",
+		      strerror(err), err);
 		goto err_close_map;
-
-	pfds = calloc(nfds, sizeof(pfds[0]));
-	if (!pfds)
-		goto err_free_rings;
-
-	for (i = 0; i < nfds; i++) {
-		rings[i].cpu = cpu + i;
-		rings[i].key = index + i;
-
-		rings[i].fd = bpf_perf_event_open(map_fd, rings[i].key,
-						  rings[i].cpu);
-		if (rings[i].fd < 0)
-			goto err_close_fds_prev;
-
-		rings[i].mem = perf_event_mmap(rings[i].fd);
-		if (!rings[i].mem)
-			goto err_close_fds_current;
-
-		pfds[i].fd = rings[i].fd;
-		pfds[i].events = POLLIN;
 	}
 
 	signal(SIGINT, int_exit);
@@ -277,34 +214,24 @@ int do_event_pipe(int argc, char **argv)
 		jsonw_start_array(json_wtr);
 
 	while (!stop) {
-		poll(pfds, nfds, 200);
-		for (i = 0; i < nfds; i++)
-			perf_event_read(&rings[i], &tmp_buf, &tmp_buf_sz);
+		err = perf_buffer__poll(pb, 200);
+		if (err < 0 && err != -EINTR) {
+			p_err("perf buffer polling failed: %s (%d)",
+			      strerror(err), err);
+			goto err_close_pb;
+		}
 	}
-	free(tmp_buf);
 
 	if (json_output)
 		jsonw_end_array(json_wtr);
 
-	for (i = 0; i < nfds; i++) {
-		perf_event_unmap(rings[i].mem);
-		close(rings[i].fd);
-	}
-	free(pfds);
-	free(rings);
+	perf_buffer__free(pb);
 	close(map_fd);
 
 	return 0;
 
-err_close_fds_prev:
-	while (i--) {
-		perf_event_unmap(rings[i].mem);
-err_close_fds_current:
-		close(rings[i].fd);
-	}
-	free(pfds);
-err_free_rings:
-	free(rings);
+err_close_pb:
+	perf_buffer__free(pb);
 err_close_map:
 	close(map_fd);
 	return -1;
-- 
2.17.1

[PATCH v6 bpf-next 5/5] libbpf: add perf_buffer_ prefix to README

[Andrii Nakryiko]

perf_buffer "object" is part of libbpf API now, add it to the list of
libbpf function prefixes.

Suggested-by: Daniel Borkman <daniel@iogearbox.net>
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
---
 tools/lib/bpf/README.rst | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/lib/bpf/README.rst b/tools/lib/bpf/README.rst
index cef7b77eab69..8928f7787f2d 100644
--- a/tools/lib/bpf/README.rst
+++ b/tools/lib/bpf/README.rst
@@ -9,7 +9,8 @@ described here. It's recommended to follow these conventions whenever a
 new function or type is added to keep libbpf API clean and consistent.
 
 All types and functions provided by libbpf API should have one of the
-following prefixes: ``bpf_``, ``btf_``, ``libbpf_``, ``xsk_``.
+following prefixes: ``bpf_``, ``btf_``, ``libbpf_``, ``xsk_``,
+``perf_buffer_``.
 
 System call wrappers
 --------------------
-- 
2.17.1

Re: [PATCH v6 bpf-next 3/5] selftests/bpf: test perf buffer API

[Yonghong Song]

On 7/5/19 11:02 PM, Andrii Nakryiko wrote:
> Add test verifying perf buffer API functionality.
> 
> Signed-off-by: Andrii Nakryiko <andriin@fb.com>
> Acked-by: Song Liu <songliubraving@fb.com>
> ---
>   .../selftests/bpf/prog_tests/perf_buffer.c    | 94 +++++++++++++++++++
>   .../selftests/bpf/progs/test_perf_buffer.c    | 25 +++++
>   2 files changed, 119 insertions(+)
>   create mode 100644 tools/testing/selftests/bpf/prog_tests/perf_buffer.c
>   create mode 100644 tools/testing/selftests/bpf/progs/test_perf_buffer.c
> 
> diff --git a/tools/testing/selftests/bpf/prog_tests/perf_buffer.c b/tools/testing/selftests/bpf/prog_tests/perf_buffer.c
> new file mode 100644
> index 000000000000..64556ab0d1a9
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/prog_tests/perf_buffer.c
> @@ -0,0 +1,94 @@
> +// SPDX-License-Identifier: GPL-2.0
> +#define _GNU_SOURCE
> +#include <pthread.h>
> +#include <sched.h>
> +#include <sys/socket.h>
> +#include <test_progs.h>
> +
> +static void on_sample(void *ctx, int cpu, void *data, __u32 size)
> +{
> +	int cpu_data = *(int *)data, duration = 0;
> +	cpu_set_t *cpu_seen = ctx;
> +
> +	if (cpu_data != cpu)
> +		CHECK(cpu_data != cpu, "check_cpu_data",
> +		      "cpu_data %d != cpu %d\n", cpu_data, cpu);
> +
> +	CPU_SET(cpu, cpu_seen);
> +}
> +
> +void test_perf_buffer(void)
> +{
> +	int err, prog_fd, nr_cpus, i, duration = 0;
> +	const char *prog_name = "kprobe/sys_nanosleep";
> +	const char *file = "./test_perf_buffer.o";
> +	struct perf_buffer_opts pb_opts = {};
> +	struct bpf_map *perf_buf_map;
> +	cpu_set_t cpu_set, cpu_seen;
> +	struct bpf_program *prog;
> +	struct bpf_object *obj;
> +	struct perf_buffer *pb;
> +	struct bpf_link *link;
> +
> +	nr_cpus = libbpf_num_possible_cpus();
> +	if (CHECK(nr_cpus < 0, "nr_cpus", "err %d\n", nr_cpus))
> +		return;
> +
> +	/* load program */
> +	err = bpf_prog_load(file, BPF_PROG_TYPE_KPROBE, &obj, &prog_fd);
> +	if (CHECK(err, "obj_load", "err %d errno %d\n", err, errno))
> +		return;
> +
> +	prog = bpf_object__find_program_by_title(obj, prog_name);
> +	if (CHECK(!prog, "find_probe", "prog '%s' not found\n", prog_name))
> +		goto out_close;
> +
> +	/* load map */
> +	perf_buf_map = bpf_object__find_map_by_name(obj, "perf_buf_map");
> +	if (CHECK(!perf_buf_map, "find_perf_buf_map", "not found\n"))
> +		goto out_close;
> +
> +	/* attach kprobe */
> +	link = bpf_program__attach_kprobe(prog, false /* retprobe */,
> +					      "sys_nanosleep");

The attach function "sys_nanosleep" won't work. You can have something
similar to attach_probe.c.

#ifdef __x86_64__
#define SYS_KPROBE_NAME "__x64_sys_nanosleep"
#else
#define SYS_KPROBE_NAME "sys_nanosleep"
#endif


> +	if (CHECK(IS_ERR(link), "attach_kprobe", "err %ld\n", PTR_ERR(link)))
> +		goto out_close;
> +
> +	/* set up perf buffer */
> +	pb_opts.sample_cb = on_sample;
> +	pb_opts.ctx = &cpu_seen;
> +	pb = perf_buffer__new(bpf_map__fd(perf_buf_map), 1, &pb_opts);
> +	if (CHECK(IS_ERR(pb), "perf_buf__new", "err %ld\n", PTR_ERR(pb)))
> +		goto out_detach;
> +
> +	/* trigger kprobe on every CPU */
> +	CPU_ZERO(&cpu_seen);
> +	for (i = 0; i < nr_cpus; i++) {
> +		CPU_ZERO(&cpu_set);
> +		CPU_SET(i, &cpu_set);
> +
> +		err = pthread_setaffinity_np(pthread_self(), sizeof(cpu_set),
> +					     &cpu_set);
> +		if (err && CHECK(err, "set_affinity", "cpu #%d, err %d\n",
> +				 i, err))
> +			goto out_detach;
> +
> +		usleep(1);
> +	}
> +
> +	/* read perf buffer */
> +	err = perf_buffer__poll(pb, 100);
> +	if (CHECK(err < 0, "perf_buffer__poll", "err %d\n", err))
> +		goto out_free_pb;
> +
> +	if (CHECK(CPU_COUNT(&cpu_seen) != nr_cpus, "seen_cpu_cnt",
> +		  "expect %d, seen %d\n", nr_cpus, CPU_COUNT(&cpu_seen)))
> +		goto out_free_pb;
> +
> +out_free_pb:
> +	perf_buffer__free(pb);
> +out_detach:
> +	bpf_link__destroy(link);
> +out_close:
> +	bpf_object__close(obj);
> +}
> diff --git a/tools/testing/selftests/bpf/progs/test_perf_buffer.c b/tools/testing/selftests/bpf/progs/test_perf_buffer.c
> new file mode 100644
> index 000000000000..876c27deb65a
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/test_perf_buffer.c
> @@ -0,0 +1,25 @@
> +// SPDX-License-Identifier: GPL-2.0
> +// Copyright (c) 2019 Facebook
> +
> +#include <linux/ptrace.h>
> +#include <linux/bpf.h>
> +#include "bpf_helpers.h"
> +
> +struct {
> +	__uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
> +	__uint(key_size, sizeof(int));
> +	__uint(value_size, sizeof(int));
> +} perf_buf_map SEC(".maps");
> +
> +SEC("kprobe/sys_nanosleep")
> +int handle_sys_nanosleep_entry(struct pt_regs *ctx)
> +{
> +	int cpu = bpf_get_smp_processor_id();
> +
> +	bpf_perf_event_output(ctx, &perf_buf_map, BPF_F_CURRENT_CPU,
> +			      &cpu, sizeof(cpu));
> +	return 0;
> +}
> +
> +char _license[] SEC("license") = "GPL";
> +__u32 _version SEC("version") = 1;
> 

Re: [PATCH v6 bpf-next 0/5] libbpf: add perf buffer abstraction and API

[Yonghong Song]

On 7/5/19 11:02 PM, Andrii Nakryiko wrote:
> This patchset adds a high-level API for setting up and polling perf buffers
> associated with BPF_MAP_TYPE_PERF_EVENT_ARRAY map. Details of APIs are
> described in corresponding commit.
> 
> Patch #1 adds a set of APIs to set up and work with perf buffer.
> Patch #2 enhances libbpf to support auto-setting PERF_EVENT_ARRAY map size.
> Patch #3 adds test.
> Patch #4 converts bpftool map event_pipe to new API.
> Patch #5 updates README to mention perf_buffer_ prefix.
> 
> v5->v6:
> - fix C99 for loop variable initialization usage (Yonghong);
> v4->v5:
> - initialize perf_buffer_raw_opts in bpftool map event_pipe (Jakub);
> - add perf_buffer_ to README;
> v3->v4:
> - fixed bpftool event_pipe cmd error handling (Jakub);
> v2->v3:
> - added perf_buffer__new_raw for more low-level control;
> - converted bpftool map event_pipe to new API (Daniel);
> - fixed bug with error handling in create_maps (Song);
> v1->v2:
> - add auto-sizing of PERF_EVENT_ARRAY maps;
> 
> Andrii Nakryiko (5):
>    libbpf: add perf buffer API
>    libbpf: auto-set PERF_EVENT_ARRAY size to number of CPUs
>    selftests/bpf: test perf buffer API
>    tools/bpftool: switch map event_pipe to libbpf's perf_buffer
>    libbpf: add perf_buffer_ prefix to README
> 
>   tools/bpf/bpftool/map_perf_ring.c             | 201 +++------
>   tools/lib/bpf/README.rst                      |   3 +-
>   tools/lib/bpf/libbpf.c                        | 397 +++++++++++++++++-
>   tools/lib/bpf/libbpf.h                        |  49 +++
>   tools/lib/bpf/libbpf.map                      |   4 +
>   .../selftests/bpf/prog_tests/perf_buffer.c    |  94 +++++
>   .../selftests/bpf/progs/test_perf_buffer.c    |  25 ++
>   7 files changed, 628 insertions(+), 145 deletions(-)
>   create mode 100644 tools/testing/selftests/bpf/prog_tests/perf_buffer.c
>   create mode 100644 tools/testing/selftests/bpf/progs/test_perf_buffer.c

With a minor comment on patch 3/5 in a different thread,
LGTM. Ack for the whole series.
Acked-by: Yonghong Song <yhs@fb.com>

Re: [PATCH v6 bpf-next 3/5] selftests/bpf: test perf buffer API

[Andrii Nakryiko]

On Sat, Jul 6, 2019 at 10:18 AM Yonghong Song <yhs@fb.com> wrote:
>
>
>
> On 7/5/19 11:02 PM, Andrii Nakryiko wrote:
> > Add test verifying perf buffer API functionality.
> >
> > Signed-off-by: Andrii Nakryiko <andriin@fb.com>
> > Acked-by: Song Liu <songliubraving@fb.com>
> > ---
> >   .../selftests/bpf/prog_tests/perf_buffer.c    | 94 +++++++++++++++++++
> >   .../selftests/bpf/progs/test_perf_buffer.c    | 25 +++++
> >   2 files changed, 119 insertions(+)
> >   create mode 100644 tools/testing/selftests/bpf/prog_tests/perf_buffer.c
> >   create mode 100644 tools/testing/selftests/bpf/progs/test_perf_buffer.c
> >
> > diff --git a/tools/testing/selftests/bpf/prog_tests/perf_buffer.c b/tools/testing/selftests/bpf/prog_tests/perf_buffer.c
> > new file mode 100644
> > index 000000000000..64556ab0d1a9
> > --- /dev/null
> > +++ b/tools/testing/selftests/bpf/prog_tests/perf_buffer.c
> > @@ -0,0 +1,94 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +#define _GNU_SOURCE
> > +#include <pthread.h>
> > +#include <sched.h>
> > +#include <sys/socket.h>
> > +#include <test_progs.h>
> > +
> > +static void on_sample(void *ctx, int cpu, void *data, __u32 size)
> > +{
> > +     int cpu_data = *(int *)data, duration = 0;
> > +     cpu_set_t *cpu_seen = ctx;
> > +
> > +     if (cpu_data != cpu)
> > +             CHECK(cpu_data != cpu, "check_cpu_data",
> > +                   "cpu_data %d != cpu %d\n", cpu_data, cpu);
> > +
> > +     CPU_SET(cpu, cpu_seen);
> > +}
> > +
> > +void test_perf_buffer(void)
> > +{
> > +     int err, prog_fd, nr_cpus, i, duration = 0;
> > +     const char *prog_name = "kprobe/sys_nanosleep";
> > +     const char *file = "./test_perf_buffer.o";
> > +     struct perf_buffer_opts pb_opts = {};
> > +     struct bpf_map *perf_buf_map;
> > +     cpu_set_t cpu_set, cpu_seen;
> > +     struct bpf_program *prog;
> > +     struct bpf_object *obj;
> > +     struct perf_buffer *pb;
> > +     struct bpf_link *link;
> > +
> > +     nr_cpus = libbpf_num_possible_cpus();
> > +     if (CHECK(nr_cpus < 0, "nr_cpus", "err %d\n", nr_cpus))
> > +             return;
> > +
> > +     /* load program */
> > +     err = bpf_prog_load(file, BPF_PROG_TYPE_KPROBE, &obj, &prog_fd);
> > +     if (CHECK(err, "obj_load", "err %d errno %d\n", err, errno))
> > +             return;
> > +
> > +     prog = bpf_object__find_program_by_title(obj, prog_name);
> > +     if (CHECK(!prog, "find_probe", "prog '%s' not found\n", prog_name))
> > +             goto out_close;
> > +
> > +     /* load map */
> > +     perf_buf_map = bpf_object__find_map_by_name(obj, "perf_buf_map");
> > +     if (CHECK(!perf_buf_map, "find_perf_buf_map", "not found\n"))
> > +             goto out_close;
> > +
> > +     /* attach kprobe */
> > +     link = bpf_program__attach_kprobe(prog, false /* retprobe */,
> > +                                           "sys_nanosleep");
>
> The attach function "sys_nanosleep" won't work. You can have something
> similar to attach_probe.c.
>
> #ifdef __x86_64__
> #define SYS_KPROBE_NAME "__x64_sys_nanosleep"
> #else
> #define SYS_KPROBE_NAME "sys_nanosleep"
> #endif
>

Yeah, this is going to be a nightmare with those arch-specific names.
I'm wondering if it's worth it to automatically do that in libbpf for
users...

But anyway, will fix in v7, thanks!

>
> > +     if (CHECK(IS_ERR(link), "attach_kprobe", "err %ld\n", PTR_ERR(link)))
> > +             goto out_close;
> > +
> > +     /* set up perf buffer */
> > +     pb_opts.sample_cb = on_sample;
> > +     pb_opts.ctx = &cpu_seen;
> > +     pb = perf_buffer__new(bpf_map__fd(perf_buf_map), 1, &pb_opts);
> > +     if (CHECK(IS_ERR(pb), "perf_buf__new", "err %ld\n", PTR_ERR(pb)))
> > +             goto out_detach;
> > +
> > +     /* trigger kprobe on every CPU */
> > +     CPU_ZERO(&cpu_seen);
> > +     for (i = 0; i < nr_cpus; i++) {
> > +             CPU_ZERO(&cpu_set);
> > +             CPU_SET(i, &cpu_set);
> > +
> > +             err = pthread_setaffinity_np(pthread_self(), sizeof(cpu_set),
> > +                                          &cpu_set);
> > +             if (err && CHECK(err, "set_affinity", "cpu #%d, err %d\n",
> > +                              i, err))
> > +                     goto out_detach;
> > +
> > +             usleep(1);
> > +     }
> > +
> > +     /* read perf buffer */
> > +     err = perf_buffer__poll(pb, 100);
> > +     if (CHECK(err < 0, "perf_buffer__poll", "err %d\n", err))
> > +             goto out_free_pb;
> > +
> > +     if (CHECK(CPU_COUNT(&cpu_seen) != nr_cpus, "seen_cpu_cnt",
> > +               "expect %d, seen %d\n", nr_cpus, CPU_COUNT(&cpu_seen)))
> > +             goto out_free_pb;
> > +
> > +out_free_pb:
> > +     perf_buffer__free(pb);
> > +out_detach:
> > +     bpf_link__destroy(link);
> > +out_close:
> > +     bpf_object__close(obj);
> > +}
> > diff --git a/tools/testing/selftests/bpf/progs/test_perf_buffer.c b/tools/testing/selftests/bpf/progs/test_perf_buffer.c
> > new file mode 100644
> > index 000000000000..876c27deb65a
> > --- /dev/null
> > +++ b/tools/testing/selftests/bpf/progs/test_perf_buffer.c
> > @@ -0,0 +1,25 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +// Copyright (c) 2019 Facebook
> > +
> > +#include <linux/ptrace.h>
> > +#include <linux/bpf.h>
> > +#include "bpf_helpers.h"
> > +
> > +struct {
> > +     __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
> > +     __uint(key_size, sizeof(int));
> > +     __uint(value_size, sizeof(int));
> > +} perf_buf_map SEC(".maps");
> > +
> > +SEC("kprobe/sys_nanosleep")
> > +int handle_sys_nanosleep_entry(struct pt_regs *ctx)
> > +{
> > +     int cpu = bpf_get_smp_processor_id();
> > +
> > +     bpf_perf_event_output(ctx, &perf_buf_map, BPF_F_CURRENT_CPU,
> > +                           &cpu, sizeof(cpu));
> > +     return 0;
> > +}
> > +
> > +char _license[] SEC("license") = "GPL";
> > +__u32 _version SEC("version") = 1;
> >