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Message-ID: <1438082255-60683-3-git-send-email-xiakaixu@huawei.com>
Date: Tue, 28 Jul 2015 11:17:33 +0000
From: Kaixu Xia <xiakaixu@...wei.com>
To: <ast@...mgrid.com>, <davem@...emloft.net>, <acme@...nel.org>,
<mingo@...hat.com>, <a.p.zijlstra@...llo.nl>,
<masami.hiramatsu.pt@...achi.com>, <jolsa@...nel.org>,
<daniel@...earbox.net>
CC: <xiakaixu@...wei.com>, <wangnan0@...wei.com>,
<linux-kernel@...r.kernel.org>, <pi3orama@....com>,
<hekuang@...wei.com>
Subject: [PATCH v4 2/4] bpf: Add new bpf map type to store the pointer to struct perf_event
Introduce a new bpf map type 'BPF_MAP_TYPE_PERF_EVENT_ARRAY'.
This map only stores the pointer to struct perf_event. The
user space event FDs from perf_event_open() syscall are converted
to the pointer to struct perf_event and stored in map.
Signed-off-by: Kaixu Xia <xiakaixu@...wei.com>
---
include/linux/bpf.h | 1 +
include/linux/perf_event.h | 2 ++
include/uapi/linux/bpf.h | 1 +
kernel/bpf/arraymap.c | 57 ++++++++++++++++++++++++++++++++++++++++++++++
kernel/bpf/verifier.c | 15 ++++++++++++
kernel/events/core.c | 17 ++++++++++++++
6 files changed, 93 insertions(+)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 610b730..3c9c0eb 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -10,6 +10,7 @@
#include <uapi/linux/bpf.h>
#include <linux/workqueue.h>
#include <linux/file.h>
+#include <linux/perf_event.h>
struct bpf_map;
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 2027809..2ea4067 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -641,6 +641,7 @@ extern int perf_event_init_task(struct task_struct *child);
extern void perf_event_exit_task(struct task_struct *child);
extern void perf_event_free_task(struct task_struct *task);
extern void perf_event_delayed_put(struct task_struct *task);
+extern struct perf_event *perf_event_get(unsigned int fd);
extern void perf_event_print_debug(void);
extern void perf_pmu_disable(struct pmu *pmu);
extern void perf_pmu_enable(struct pmu *pmu);
@@ -979,6 +980,7 @@ static inline int perf_event_init_task(struct task_struct *child) { return 0; }
static inline void perf_event_exit_task(struct task_struct *child) { }
static inline void perf_event_free_task(struct task_struct *task) { }
static inline void perf_event_delayed_put(struct task_struct *task) { }
+static struct perf_event *perf_event_get(unsigned int fd) { return NULL; }
static inline void perf_event_print_debug(void) { }
static inline int perf_event_task_disable(void) { return -EINVAL; }
static inline int perf_event_task_enable(void) { return -EINVAL; }
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 29ef6f9..69a1f6b 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -114,6 +114,7 @@ enum bpf_map_type {
BPF_MAP_TYPE_HASH,
BPF_MAP_TYPE_ARRAY,
BPF_MAP_TYPE_PROG_ARRAY,
+ BPF_MAP_TYPE_PERF_EVENT_ARRAY,
};
enum bpf_prog_type {
diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
index 4784cdc..a9e0235 100644
--- a/kernel/bpf/arraymap.c
+++ b/kernel/bpf/arraymap.c
@@ -297,3 +297,60 @@ static int __init register_prog_array_map(void)
return 0;
}
late_initcall(register_prog_array_map);
+
+static void *perf_event_fd_array_get_ptr(struct bpf_array *array, int fd)
+{
+ struct perf_event *event;
+
+ event = perf_event_get(fd);
+ if (IS_ERR(event))
+ return event;
+
+ /*
+ * prevent some crazy events so we can make our life easier
+ */
+ if (event->attr.type != PERF_TYPE_RAW &&
+ event->attr.type != PERF_TYPE_HARDWARE) {
+ perf_event_release_kernel(event);
+ return ERR_PTR(-EINVAL);
+ }
+ return event;
+}
+
+static void perf_event_fd_array_put_ptr(struct bpf_array *array, void *ptr)
+{
+ struct perf_event *event = (struct perf_event *)ptr;
+
+ perf_event_release_kernel(event);
+}
+
+static const struct fd_array_map_ops perf_event_fd_array_map_ops = {
+ .get_ptr = perf_event_fd_array_get_ptr,
+ .put_ptr = perf_event_fd_array_put_ptr,
+};
+
+static struct bpf_map *perf_event_array_map_alloc(union bpf_attr *attr)
+{
+ return fd_array_map_alloc(attr, &perf_event_fd_array_map_ops);
+}
+
+static const struct bpf_map_ops perf_event_array_ops = {
+ .map_alloc = perf_event_array_map_alloc,
+ .map_free = fd_array_map_free,
+ .map_get_next_key = array_map_get_next_key,
+ .map_lookup_elem = fd_array_map_lookup_elem,
+ .map_update_elem = fd_array_map_update_elem,
+ .map_delete_elem = fd_array_map_delete_elem,
+};
+
+static struct bpf_map_type_list perf_event_array_type __read_mostly = {
+ .ops = &perf_event_array_ops,
+ .type = BPF_MAP_TYPE_PERF_EVENT_ARRAY,
+};
+
+static int __init register_perf_event_array_map(void)
+{
+ bpf_register_map_type(&perf_event_array_type);
+ return 0;
+}
+late_initcall(register_perf_event_array_map);
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 039d866..c70f7e7 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -924,6 +924,21 @@ static int check_call(struct verifier_env *env, int func_id)
*/
return -EINVAL;
+ if (map && map->map_type == BPF_MAP_TYPE_PERF_EVENT_ARRAY &&
+ func_id != BPF_FUNC_perf_event_read)
+ /* perf_event_array map type needs extra care:
+ * only allow to pass it into bpf_perf_event_read() for now.
+ * bpf_map_update/delete_elem() must only be done via syscall
+ */
+ return -EINVAL;
+
+ if (func_id == BPF_FUNC_perf_event_read &&
+ map->map_type != BPF_MAP_TYPE_PERF_EVENT_ARRAY)
+ /* don't allow any other map type to be passed into
+ * bpf_perf_event_read()
+ */
+ return -EINVAL;
+
return 0;
}
diff --git a/kernel/events/core.c b/kernel/events/core.c
index d3dae34..58f0d47 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -8574,6 +8574,23 @@ void perf_event_delayed_put(struct task_struct *task)
WARN_ON_ONCE(task->perf_event_ctxp[ctxn]);
}
+struct perf_event *perf_event_get(unsigned int fd)
+{
+ int err;
+ struct fd f;
+ struct perf_event *event;
+
+ err = perf_fget_light(fd, &f);
+ if (err)
+ return ERR_PTR(err);
+
+ event = f.file->private_data;
+ atomic_long_inc(&event->refcount);
+ fdput(f);
+
+ return event;
+}
+
/*
* inherit a event from parent task to child task:
*/
--
1.8.3.4
--
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