Commit e87c6bc3852b ("bpf: permit multiple bpf attachments
for a single perf event") added support to attach multiple
bpf programs to a single perf event.
Commit 2541517c32be ("tracing, perf: Implement BPF programs
attached to kprobes") utilized the existing perf ioctl
interface and added the command PERF_EVENT_IOC_SET_BPF
to attach a bpf program to a tracepoint.
This patch adds a new ioctl
command, given a perf event fd, to query the bpf program array
attached to the same perf tracepoint event.
The new uapi ioctl command:
PERF_EVENT_IOC_QUERY_BPF
The new uapi/linux/perf_event.h structure:
struct perf_event_query_bpf {
__u64 prog_ids;
__u32 prog_cnt;
};
The usage:
struct perf_event_query_bpf query;
query.prog_ids = (__u64)usr_prog_ids_buf;
query.prog_cnt = usr_prog_ids_buf_len;
err = ioctl(pmu_efd, PERF_EVENT_IOC_QUERY_BPF, &query);
Signed-off-by: Yonghong Song <y...@fb.com>
Acked-by: Alexei Starovoitov <a...@kernel.org>
---
include/linux/bpf.h | 4 ++++
include/uapi/linux/perf_event.h | 6 ++++++
kernel/bpf/core.c | 21 +++++++++++++++++++++
kernel/events/core.c | 3 +++
kernel/trace/bpf_trace.c | 23 +++++++++++++++++++++++
5 files changed, 57 insertions(+)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index e55e425..f812ac5 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -254,6 +254,7 @@ typedef unsigned long (*bpf_ctx_copy_t)(void *dst, const
void *src,
u64 bpf_event_output(struct bpf_map *map, u64 flags, void *meta, u64 meta_size,
void *ctx, u64 ctx_size, bpf_ctx_copy_t ctx_copy);
+int bpf_event_query_prog_array(struct perf_event *event, void __user *info);
int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr,
union bpf_attr __user *uattr);
@@ -285,6 +286,9 @@ int bpf_prog_array_copy_to_user(struct bpf_prog_array __rcu
*progs,
void bpf_prog_array_delete_safe(struct bpf_prog_array __rcu *progs,
struct bpf_prog *old_prog);
+int bpf_prog_array_copy_info(struct bpf_prog_array __rcu *array,
+ __u32 __user *prog_ids, u32 request_cnt,
+ __u32 __user *prog_cnt);
int bpf_prog_array_copy(struct bpf_prog_array __rcu *old_array,
struct bpf_prog *exclude_prog,
struct bpf_prog *include_prog,
diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
index b9a4953..fee0b43 100644
--- a/include/uapi/linux/perf_event.h
+++ b/include/uapi/linux/perf_event.h
@@ -418,6 +418,11 @@ struct perf_event_attr {
__u16 __reserved_2; /* align to __u64 */
};
+struct perf_event_query_bpf {
+ __u64 prog_ids;
+ __u32 prog_cnt;
+};
+
#define perf_flags(attr) (*(&(attr)->read_format + 1))
/*
@@ -433,6 +438,7 @@ struct perf_event_attr {
#define PERF_EVENT_IOC_ID _IOR('$', 7, __u64 *)
#define PERF_EVENT_IOC_SET_BPF _IOW('$', 8, __u32)
#define PERF_EVENT_IOC_PAUSE_OUTPUT _IOW('$', 9, __u32)
+#define PERF_EVENT_IOC_QUERY_BPF _IOWR('$', 10, struct
perf_event_query_bpf *)
enum perf_event_ioc_flags {
PERF_IOC_FLAG_GROUP = 1U << 0,
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 86b50aa..35b427aa 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -1462,6 +1462,8 @@ int bpf_prog_array_copy_to_user(struct bpf_prog_array
__rcu *progs,
rcu_read_lock();
prog = rcu_dereference(progs)->progs;
for (; *prog; prog++) {
+ if (*prog == &dummy_bpf_prog.prog)
+ continue;
id = (*prog)->aux->id;
if (copy_to_user(prog_ids + i, &id, sizeof(id))) {
rcu_read_unlock();
@@ -1545,6 +1547,25 @@ int bpf_prog_array_copy(struct bpf_prog_array __rcu
*old_array,
return 0;
}
+int bpf_prog_array_copy_info(struct bpf_prog_array __rcu *array,
+ __u32 __user *prog_ids, u32 request_cnt,
+ __u32 __user *prog_cnt)
+{
+ u32 cnt = 0;
+
+ if (array)
+ cnt = bpf_prog_array_length(array);
+
+ if (copy_to_user(prog_cnt, &cnt, sizeof(cnt)))
+ return -EFAULT;
+
+ /* return early if user requested only program count or nothing to copy
*/
+ if (!request_cnt || !prog_ids || !cnt)
+ return 0;
+
+ return bpf_prog_array_copy_to_user(array, prog_ids, request_cnt);
+}
+
static void bpf_prog_free_deferred(struct work_struct *work)
{
struct bpf_prog_aux *aux;
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 16beab4..f10609e 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -4723,6 +4723,9 @@ static long _perf_ioctl(struct perf_event *event,
unsigned int cmd, unsigned lon
rcu_read_unlock();
return 0;
}
+
+ case PERF_EVENT_IOC_QUERY_BPF:
+ return bpf_event_query_prog_array(event, (void __user *)arg);
default:
return -ENOTTY;
}
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 0ce99c3..81eedb2 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -820,3 +820,26 @@ void perf_event_detach_bpf_prog(struct perf_event *event)
unlock:
mutex_unlock(&bpf_event_mutex);
}
+
+int bpf_event_query_prog_array(struct perf_event *event, void __user *info)
+{
+ struct perf_event_query_bpf __user *uquery = info;
+ struct perf_event_query_bpf query = {};
+ int ret;
+
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+ if (event->attr.type != PERF_TYPE_TRACEPOINT)
+ return -EINVAL;
+ if (copy_from_user(&query, uquery, sizeof(query)))
+ return -EFAULT;
+
+ mutex_lock(&bpf_event_mutex);
+ ret = bpf_prog_array_copy_info(event->tp_event->prog_array,
+ u64_to_user_ptr(query.prog_ids),
+ query.prog_cnt,
+ &uquery->prog_cnt);
+ mutex_unlock(&bpf_event_mutex);
+
+ return ret;
+}
--
2.9.5
