[PATCH 08/46] perf data: Support converting data from bpf_perf_event_output()

Wang Nan
2016-02-26T09:52:03Z

bpf_perf_event_output() outputs data through sample->raw_data. This
patch adds support to convert those data into CTF. A python script
then can be used to process output data from BPF programs.

Test result:

# cat ./test_bpf_output_2.c
/************************ BEGIN **************************/
#include <uapi/linux/bpf.h>
struct bpf_map_def {
unsigned int type;
unsigned int key_size;
unsigned int value_size;
unsigned int max_entries;
};
#define SEC(NAME) __attribute__((section(NAME), used))
static u64 (*ktime_get_ns)(void) =
(void *)BPF_FUNC_ktime_get_ns;
static int (*trace_printk)(const char *fmt, int fmt_size, ...) =
(void *)BPF_FUNC_trace_printk;
static int (*get_smp_processor_id)(void) =
(void *)BPF_FUNC_get_smp_processor_id;
static int (*perf_event_output)(void *, struct bpf_map_def *, int, void *, unsigned long) =
(void *)BPF_FUNC_perf_event_output;

struct bpf_map_def SEC("maps") channel = {
.type = BPF_MAP_TYPE_PERF_EVENT_ARRAY,
.key_size = sizeof(int),
.value_size = sizeof(u32),
.max_entries = __NR_CPUS__,
};

static inline int __attribute__((always_inline))
func(void *ctx, int type)
{
struct {
u64 ktime;
int type;
} __attribute__((packed)) output_data;
char error_data[] = "Error: failed to output\n";
int err;

output_data.type = type;
output_data.ktime = ktime_get_ns();
err = perf_event_output(ctx, &channel, get_smp_processor_id(),
&output_data, sizeof(output_data));
if (err)
trace_printk(error_data, sizeof(error_data));
return 0;
}
SEC("func_begin=sys_nanosleep")
int func_begin(void *ctx) {return func(ctx, 1);}
SEC("func_end=sys_nanosleep%return")
int func_end(void *ctx) { return func(ctx, 2);}
char _license[] SEC("license") = "GPL";
int _version SEC("version") = LINUX_VERSION_CODE;
/************************* END ***************************/

# ./perf record -e bpf-output/no-inherit,name=evt/ \
-e ./test_bpf_output_2.c/map:channel.event=evt/ \
usleep 100000
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.012 MB perf.data (2 samples) ]

# ./perf script
usleep 14942 92503.198504: evt: ffffffff810e0ba1 sys_nanosleep (/lib/modules/4.3.0....
usleep 14942 92503.298562: evt: ffffffff810585e9 kretprobe_trampoline_holder (/lib....

# ./perf data convert --to-ctf ./out.ctf
[ perf data convert: Converted 'perf.data' into CTF data './out.ctf' ]
[ perf data convert: Converted and wrote 0.000 MB (2 samples) ]

# babeltrace ./out.ctf
[01:41:43.198504134] (+?.?????????) evt: { cpu_id = 0 }, { perf_ip = 0xFFFFFFFF810E0BA1, perf_tid = 14942, perf_pid = 14942, perf_id = 1044, raw_len = 3, raw_data = [ [0] = 0x32C0C07B, [1] = 0x5421, [2] = 0x1 ] }
[01:41:43.298562257] (+0.100058123) evt: { cpu_id = 0 }, { perf_ip = 0xFFFFFFFF810585E9, perf_tid = 14942, perf_pid = 14942, perf_id = 1044, raw_len = 3, raw_data = [ [0] = 0x38B77FAA, [1] = 0x5421, [2] = 0x2 ] }

# cat ./test_bpf_output_2.py
from babeltrace import TraceCollection
tc = TraceCollection()
tc.add_trace('./out.ctf', 'ctf')
d = {1:[], 2:[]}
for event in tc.events:
if not event.name.startswith('evt'):
continue
raw_data = event['raw_data']
(time, type) = ((raw_data[0] + (raw_data[1] << 32)), raw_data[2])
d[type].append(time)
print(list(map(lambda i: d[2][i] - d[1][i], range(len(d[1])))));

# python3 ./test_bpf_output_2.py
[100056879]

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
---
tools/perf/util/data-convert-bt.c | 112 +++++++++++++++++++++++++++++++++++++-
1 file changed, 111 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/data-convert-bt.c b/tools/perf/util/data-convert-bt.c
index 6729f4d..1f608a6 100644
--- a/tools/perf/util/data-convert-bt.c
+++ b/tools/perf/util/data-convert-bt.c
@@ -352,6 +352,84 @@ static int add_tracepoint_values(struct ctf_writer *cw,
return ret;
}

+static int
+add_bpf_output_values(struct bt_ctf_event_class *event_class,
+ struct bt_ctf_event *event,
+ struct perf_sample *sample)
+{
+ struct bt_ctf_field_type *len_type, *seq_type;
+ struct bt_ctf_field *len_field, *seq_field;
+ unsigned int raw_size = sample->raw_size;
+ unsigned int nr_elements = raw_size / sizeof(u32);
+ unsigned int i;
+ int ret;
+
+ if (nr_elements * sizeof(u32) != raw_size)
+ pr_warning("Incorrect raw_size (%u) in bpf output event, skip %lu bytes\n",
+ raw_size, nr_elements * sizeof(u32) - raw_size);
+
+ len_type = bt_ctf_event_class_get_field_by_name(event_class, "raw_len");
+ len_field = bt_ctf_field_create(len_type);
+ if (!len_field) {
+ pr_err("failed to create 'raw_len' for bpf output event\n");
+ ret = -1;
+ goto put_len_type;
+ }
+
+ ret = bt_ctf_field_unsigned_integer_set_value(len_field, nr_elements);
+ if (ret) {
+ pr_err("failed to set field value for raw_len\n");
+ goto put_len_field;
+ }
+ ret = bt_ctf_event_set_payload(event, "raw_len", len_field);
+ if (ret) {
+ pr_err("failed to set payload to raw_len\n");
+ goto put_len_field;
+ }
+
+ seq_type = bt_ctf_event_class_get_field_by_name(event_class, "raw_data");
+ seq_field = bt_ctf_field_create(seq_type);
+ if (!seq_field) {
+ pr_err("failed to create 'raw_data' for bpf output event\n");
+ ret = -1;
+ goto put_seq_type;
+ }
+
+ ret = bt_ctf_field_sequence_set_length(seq_field, len_field);
+ if (ret) {
+ pr_err("failed to set length of 'raw_data'\n");
+ goto put_seq_field;
+ }
+
+ for (i = 0; i < nr_elements; i++) {
+ struct bt_ctf_field *elem_field =
+ bt_ctf_field_sequence_get_field(seq_field, i);
+
+ ret = bt_ctf_field_unsigned_integer_set_value(elem_field,
+ ((u32 *)(sample->raw_data))[i]);
+
+ bt_ctf_field_put(elem_field);
+ if (ret) {
+ pr_err("failed to set raw_data[%d]\n", i);
+ goto put_seq_field;
+ }
+ }
+
+ ret = bt_ctf_event_set_payload(event, "raw_data", seq_field);
+ if (ret)
+ pr_err("failed to set payload for raw_data\n");
+
+put_seq_field:
+ bt_ctf_field_put(seq_field);
+put_seq_type:
+ bt_ctf_field_type_put(seq_type);
+put_len_field:
+ bt_ctf_field_put(len_field);
+put_len_type:
+ bt_ctf_field_type_put(len_type);
+ return ret;
+}
+
static int add_generic_values(struct ctf_writer *cw,
struct bt_ctf_event *event,
struct perf_evsel *evsel,
@@ -597,6 +675,12 @@ static int process_sample_event(struct perf_tool *tool,
return -1;
}

+ if (perf_evsel__is_bpf_output(evsel)) {
+ ret = add_bpf_output_values(event_class, event, sample);
+ if (ret)
+ return -1;
+ }
+
cs = ctf_stream(cw, get_sample_cpu(cw, sample, evsel));
if (cs) {
if (is_flush_needed(cs))
@@ -744,6 +828,25 @@ static int add_tracepoint_types(struct ctf_writer *cw,
return ret;
}

+static int add_bpf_output_types(struct ctf_writer *cw,
+ struct bt_ctf_event_class *class)
+{
+ struct bt_ctf_field_type *len_type = cw->data.u32;
+ struct bt_ctf_field_type *seq_base_type = cw->data.u32_hex;
+ struct bt_ctf_field_type *seq_type;
+ int ret;
+
+ ret = bt_ctf_event_class_add_field(class, len_type, "raw_len");
+ if (ret)
+ return ret;
+
+ seq_type = bt_ctf_field_type_sequence_create(seq_base_type, "raw_len");
+ if (!seq_type)
+ return -1;
+
+ return bt_ctf_event_class_add_field(class, seq_type, "raw_data");
+}
+
static int add_generic_types(struct ctf_writer *cw, struct perf_evsel *evsel,
struct bt_ctf_event_class *event_class)
{
@@ -755,7 +858,8 @@ static int add_generic_types(struct ctf_writer *cw, struct perf_evsel *evsel,
* ctf event header
* PERF_SAMPLE_READ - TODO
* PERF_SAMPLE_CALLCHAIN - TODO
- * PERF_SAMPLE_RAW - tracepoint fields are handled separately
+ * PERF_SAMPLE_RAW - tracepoint fields and BPF output
+ * are handled separately
* PERF_SAMPLE_BRANCH_STACK - TODO
* PERF_SAMPLE_REGS_USER - TODO
* PERF_SAMPLE_STACK_USER - TODO
@@ -824,6 +928,12 @@ static int add_event(struct ctf_writer *cw, struct perf_evsel *evsel)
goto err;
}

+ if (perf_evsel__is_bpf_output(evsel)) {
+ ret = add_bpf_output_types(cw, event_class);
+ if (ret)
+ goto err;
+ }
+
ret = bt_ctf_stream_class_add_event_class(cw->stream_class, event_class);
if (ret) {
pr("Failed to add event class into stream.\n");
--
1.8.3.4