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From: Kaixu Xia <xiakaixu@huawei.com>
To: <ast@plumgrid.com>, <davem@davemloft.net>, <acme@kernel.org>,
	<mingo@redhat.com>, <a.p.zijlstra@chello.nl>,
	<masami.hiramatsu.pt@hitachi.com>, <jolsa@kernel.org>
Cc: <xiakaixu@huawei.com>, <wangnan0@huawei.com>,
	<linux-kernel@vger.kernel.org>, <pi3orama@163.com>,
	<hekuang@huawei.com>
Subject: [PATCH v3 2/3] bpf: Implement function bpf_perf_event_read() that get the selected hardware PMU conuter
Date: Thu, 23 Jul 2015 09:42:41 +0000	[thread overview]
Message-ID: <1437644562-84431-3-git-send-email-xiakaixu@huawei.com> (raw)
In-Reply-To: <1437644562-84431-1-git-send-email-xiakaixu@huawei.com>

According to the perf_event_map_fd and index, the function
bpf_perf_event_read() can convert the corresponding map
value to the pointer to struct perf_event and return the
Hardware PMU counter value.

Signed-off-by: Kaixu Xia <xiakaixu@huawei.com>
---
 include/linux/bpf.h        |  1 +
 include/linux/perf_event.h |  3 ++-
 include/uapi/linux/bpf.h   |  1 +
 kernel/bpf/helpers.c       | 36 ++++++++++++++++++++++++++++++++++++
 kernel/events/core.c       |  4 ++--
 kernel/trace/bpf_trace.c   |  2 ++
 6 files changed, 44 insertions(+), 3 deletions(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 9cf74c0..0954b8f 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -187,6 +187,7 @@ extern const struct bpf_func_proto bpf_map_lookup_elem_proto;
 extern const struct bpf_func_proto bpf_map_update_elem_proto;
 extern const struct bpf_func_proto bpf_map_delete_elem_proto;
 
+extern const struct bpf_func_proto bpf_perf_event_read_proto;
 extern const struct bpf_func_proto bpf_get_prandom_u32_proto;
 extern const struct bpf_func_proto bpf_get_smp_processor_id_proto;
 extern const struct bpf_func_proto bpf_tail_call_proto;
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 2ea4067..899abcb 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -662,7 +662,8 @@ extern void perf_pmu_migrate_context(struct pmu *pmu,
 				int src_cpu, int dst_cpu);
 extern u64 perf_event_read_value(struct perf_event *event,
 				 u64 *enabled, u64 *running);
-
+extern void __perf_event_read(void *info);
+extern u64 perf_event_count(struct perf_event *event);
 
 struct perf_sample_data {
 	/*
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 69a1f6b..b9b13ce 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -250,6 +250,7 @@ enum bpf_func_id {
 	 * Return: 0 on success
 	 */
 	BPF_FUNC_get_current_comm,
+	BPF_FUNC_perf_event_read,	/* u64 bpf_perf_event_read(&map, index) */
 	__BPF_FUNC_MAX_ID,
 };
 
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 1447ec0..aab219d 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -182,3 +182,39 @@ const struct bpf_func_proto bpf_get_current_comm_proto = {
 	.arg1_type	= ARG_PTR_TO_STACK,
 	.arg2_type	= ARG_CONST_STACK_SIZE,
 };
+
+static u64 bpf_perf_event_read(u64 r1, u64 index, u64 r3, u64 r4, u64 r5)
+{
+	struct bpf_map *map = (struct bpf_map *) (unsigned long) r1;
+	struct bpf_array *array = container_of(map, struct bpf_array, map);
+	struct perf_event *event;
+
+	if (index >= array->map.max_entries)
+		return -E2BIG;
+
+	event = array->events[index];
+	if (!event)
+		return -EBADF;
+
+	if (event->state != PERF_EVENT_STATE_ACTIVE)
+		return -ENOENT;
+
+	if (event->oncpu != raw_smp_processor_id() &&
+	    event->ctx->task != current)
+		return -EINVAL;
+
+	if (event->attr.inherit)
+		return -EINVAL;
+
+	__perf_event_read(event);
+
+	return perf_event_count(event);
+}
+
+const struct bpf_func_proto bpf_perf_event_read_proto = {
+	.func		= bpf_perf_event_read,
+	.gpl_only	= false,
+	.ret_type	= RET_INTEGER,
+	.arg1_type	= ARG_CONST_MAP_PTR,
+	.arg2_type	= ARG_ANYTHING,
+};
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 08cb467..c59d9c6 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -3177,7 +3177,7 @@ void perf_event_exec(void)
 /*
  * Cross CPU call to read the hardware event
  */
-static void __perf_event_read(void *info)
+void __perf_event_read(void *info)
 {
 	struct perf_event *event = info;
 	struct perf_event_context *ctx = event->ctx;
@@ -3204,7 +3204,7 @@ static void __perf_event_read(void *info)
 	raw_spin_unlock(&ctx->lock);
 }
 
-static inline u64 perf_event_count(struct perf_event *event)
+u64 perf_event_count(struct perf_event *event)
 {
 	if (event->pmu->count)
 		return event->pmu->count(event);
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 88a041a..9cf094f 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -183,6 +183,8 @@ static const struct bpf_func_proto *kprobe_prog_func_proto(enum bpf_func_id func
 		return bpf_get_trace_printk_proto();
 	case BPF_FUNC_get_smp_processor_id:
 		return &bpf_get_smp_processor_id_proto;
+	case BPF_FUNC_perf_event_read:
+		return &bpf_perf_event_read_proto;
 	default:
 		return NULL;
 	}
-- 
1.8.3.4


  parent reply	other threads:[~2015-07-23  9:43 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-07-23  9:42 [PATCH v3 0/3] bpf: Introduce the new ability of eBPF programs to access hardware PMU counter Kaixu Xia
2015-07-23  9:42 ` [PATCH v3 1/3] bpf: Add new bpf map type to store the pointer to struct perf_event Kaixu Xia
2015-07-23 22:54   ` Alexei Starovoitov
2015-07-24  2:22     ` xiakaixu
2015-07-24  2:26       ` Alexei Starovoitov
2015-08-03  9:38   ` Peter Zijlstra
2015-07-23  9:42 ` Kaixu Xia [this message]
2015-07-23 22:56   ` [PATCH v3 2/3] bpf: Implement function bpf_perf_event_read() that get the selected hardware PMU conuter Alexei Starovoitov
2015-07-24  1:57     ` xiakaixu
2015-08-03  9:34   ` Peter Zijlstra
2015-08-03 10:32     ` xiakaixu
2015-07-23  9:42 ` [PATCH v3 3/3] samples/bpf: example of get selected PMU counter value Kaixu Xia
2015-07-23 22:59   ` Alexei Starovoitov
2015-07-24  1:54     ` xiakaixu
2015-07-24  2:23       ` Alexei Starovoitov

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