Hello Vince,
On 07/10/2018 07:14 PM, Vince Weaver wrote:
The PERF_EVENT_IOC_QUERY_BPF ioctl was introduced in Linux 4.16.
Signed-off-by: Vince Weaver <vincent.weaver@xxxxxxxxx>
Thanks.
Patch applied.
Cheers,
Michael
diff --git a/man2/perf_event_open.2 b/man2/perf_event_open.2
index b598acf17..a464e95a2 100644
--- a/man2/perf_event_open.2
+++ b/man2/perf_event_open.2
@@ -2945,6 +2945,47 @@ even though the ring-buffer remains empty.
The argument is an unsigned 32-bit integer.
A nonzero value pauses the ring-buffer, while a
zero value resumes the ring-buffer.
+.TP
+.BR PERF_EVENT_IOC_QUERY_BPF " (since Linux 4.16)"
+.\" commit f371b304f12e31fe30207c41ca7754564e0ea4dc
+This allows querying which Berkeley Packet Filter (BPF)
+programs are attached to an existing kprobe tracepoint.
+You can only attach one BPF program per event, but you can
+have multiple events attached to a tracepoint.
+Querying this value on one tracepoint event returns the id
+of all BPF programs in all events attached to the tracepoint.
+You need
+.B CAP_SYS_ADMIN
+privileges to use this ioctl.
+.IP
+The argument is a pointer to a structure
+.in +4n
+.EX
+struct perf_event_query_bpf {
+ __u32 ids_len;
+ __u32 prog_cnt;
+ __u32 ids[0];
+};
+.EE
+.IP
+The
+.I ids_len
+field indicates the number of ids that can fit in the provided
+.I ids
+array.
+The
+.I prog_cnt
+value is filled in by the kernel with the number of attached
+BPF programs.
+The
+.I ids
+array is filled with the id of each attached BPF program.
+If there are more programs than will fit in the array, then the
+kernel will return
+.B ENOSPC
+and
+.I ids_len
+will indicate the number of program IDs that were successfully copied.
.SS Using prctl(2)
A process can enable or disable all currently open event groups
using the
