From: Yonghong Song <yhs@fb•com>
To: <peterz@infradead•org>, <rostedt@goodmis•org>, <ast@fb•com>,
<daniel@iogearbox•net>, <netdev@vger•kernel.org>
Cc: <kernel-team@fb•com>
Subject: [PATCH net-next 3/4] bpf: add helper bpf_perf_prog_read_time
Date: Fri, 1 Sep 2017 09:53:56 -0700 [thread overview]
Message-ID: <20170901165357.465121-4-yhs@fb.com> (raw)
In-Reply-To: <20170901165357.465121-1-yhs@fb.com>
This patch adds helper bpf_perf_prog_read_time for perf event based bpf
programs, to read event enabled/running time.
The enabled/running time is accumulated since the perf event open.
The typical use case for perf event based bpf program is to attach itself
to a single event. In such cases, if it is desirable to get scaling factor
between two bpf invocations, users can can save the time values in a map,
and use the value from the map and the current value to calculate
the scaling factor.
Signed-off-by: Yonghong Song <yhs@fb•com>
---
include/linux/perf_event.h | 1 +
include/uapi/linux/bpf.h | 8 ++++++++
kernel/events/core.c | 1 +
kernel/trace/bpf_trace.c | 24 ++++++++++++++++++++++++
4 files changed, 34 insertions(+)
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 7fd5e94..92955fc 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -821,6 +821,7 @@ struct perf_output_handle {
struct bpf_perf_event_data_kern {
struct pt_regs *regs;
struct perf_sample_data *data;
+ struct perf_event *event;
};
#ifdef CONFIG_CGROUP_PERF
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 9c23bef..1ae55c8 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -590,6 +590,13 @@ union bpf_attr {
* @counter_time_buf: buf to fill
* @buf_size: size of the counter_time_buf
* Return: 0 on success or negative error code
+ *
+ * int bpf_perf_prog_read_time(ctx, time_buf, buf_size)
+ * Read perf event enabled and running time
+ * @ctx: pointer to ctx
+ * @time_buf: buf to fill
+ * @buf_size: size of the time_buf
+ * Return : 0 on success or negative error code
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@@ -647,6 +654,7 @@ union bpf_attr {
FN(sk_redirect_map), \
FN(sock_map_update), \
FN(perf_read_counter_time), \
+ FN(perf_prog_read_time), \
/* integer value in 'imm' field of BPF_CALL instruction selects which helper
* function eBPF program intends to call
diff --git a/kernel/events/core.c b/kernel/events/core.c
index ef5c7fb..1f16f1f 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -8019,6 +8019,7 @@ static void bpf_overflow_handler(struct perf_event *event,
struct bpf_perf_event_data_kern ctx = {
.data = data,
.regs = regs,
+ .event = event,
};
int ret = 0;
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index b807b1a..e97620a 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -608,6 +608,19 @@ BPF_CALL_3(bpf_get_stackid_tp, void *, tp_buff, struct bpf_map *, map,
flags, 0, 0);
}
+BPF_CALL_3(bpf_perf_prog_read_time_tp, void *, ctx, struct bpf_perf_time *,
+ time_buf, u32, size)
+{
+ struct bpf_perf_event_data_kern *kctx = (struct bpf_perf_event_data_kern *)ctx;
+ u64 now;
+
+ if (size != sizeof(struct bpf_perf_time))
+ return -EINVAL;
+
+ calc_timer_values(kctx->event, &now, &time_buf->enabled, &time_buf->running);
+ return 0;
+}
+
static const struct bpf_func_proto bpf_get_stackid_proto_tp = {
.func = bpf_get_stackid_tp,
.gpl_only = true,
@@ -617,6 +630,15 @@ static const struct bpf_func_proto bpf_get_stackid_proto_tp = {
.arg3_type = ARG_ANYTHING,
};
+static const struct bpf_func_proto bpf_perf_prog_read_time_proto_tp = {
+ .func = bpf_perf_prog_read_time_tp,
+ .gpl_only = true,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_CTX,
+ .arg2_type = ARG_PTR_TO_UNINIT_MEM,
+ .arg3_type = ARG_CONST_SIZE,
+};
+
static const struct bpf_func_proto *tp_prog_func_proto(enum bpf_func_id func_id)
{
switch (func_id) {
@@ -624,6 +646,8 @@ static const struct bpf_func_proto *tp_prog_func_proto(enum bpf_func_id func_id)
return &bpf_perf_event_output_proto_tp;
case BPF_FUNC_get_stackid:
return &bpf_get_stackid_proto_tp;
+ case BPF_FUNC_perf_prog_read_time:
+ return &bpf_perf_prog_read_time_proto_tp;
default:
return tracing_func_proto(func_id);
}
--
2.9.5
next prev parent reply other threads:[~2017-09-01 16:54 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-01 16:53 [PATCH net-next 0/4] bpf: add two helpers to read perf event enabled/running time Yonghong Song
2017-09-01 16:53 ` [PATCH net-next 1/4] bpf: add helper bpf_perf_read_counter_time for perf event array map Yonghong Song
2017-09-01 20:29 ` Alexei Starovoitov
2017-09-01 20:50 ` Peter Zijlstra
2017-09-01 21:01 ` Yonghong Song
2017-09-01 20:41 ` Peter Zijlstra
2017-09-01 16:53 ` [PATCH net-next 2/4] bpf: add a test case for helper bpf_perf_read_counter_time Yonghong Song
2017-09-01 16:53 ` Yonghong Song [this message]
2017-09-01 16:53 ` [PATCH net-next 4/4] bpf: add a test case for helper bpf_perf_prog_read_time Yonghong Song
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