Add ring_buffer__query to fetch ringbuffer information from userspace,
working the same as the bpf_ringbuf_query helper.
Signed-off-by: Martin Kelly <martin.kelly@xxxxxxxxxxxxxxx>
---
tools/lib/bpf/libbpf.h | 2 ++
tools/lib/bpf/libbpf.map | 1 +
tools/lib/bpf/ringbuf.c | 33 +++++++++++++++++++++++++++++++++
3 files changed, 36 insertions(+)
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 0e52621cba43..4ceed3ffabc2 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -1248,6 +1248,8 @@ LIBBPF_API int ring_buffer__add(struct ring_buffer *rb, int map_fd,
LIBBPF_API int ring_buffer__poll(struct ring_buffer *rb, int timeout_ms);
LIBBPF_API int ring_buffer__consume(struct ring_buffer *rb);
LIBBPF_API int ring_buffer__epoll_fd(const struct ring_buffer *rb);
+LIBBPF_API __u64 ring_buffer__query(struct ring_buffer *rb, unsigned int index,
+ __u64 flags);
struct user_ring_buffer_opts {
size_t sz; /* size of this struct, for forward/backward compatibility */
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index 57712321490f..cbb3dc39446e 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -400,4 +400,5 @@ LIBBPF_1.3.0 {
bpf_program__attach_netfilter;
bpf_program__attach_tcx;
bpf_program__attach_uprobe_multi;
+ ring_buffer__query;
} LIBBPF_1.2.0;
diff --git a/tools/lib/bpf/ringbuf.c b/tools/lib/bpf/ringbuf.c
index 02199364db13..85ccac7a2db3 100644
--- a/tools/lib/bpf/ringbuf.c
+++ b/tools/lib/bpf/ringbuf.c
@@ -69,6 +69,15 @@ static void ringbuf_unmap_ring(struct ring_buffer *rb, struct ring *r)
}
}
+static unsigned long ringbuf_avail_data_sz(struct ring *r)
+{
+ unsigned long cons_pos, prod_pos;
+
+ cons_pos = smp_load_acquire(r->consumer_pos);
+ prod_pos = smp_load_acquire(r->producer_pos);
+ return prod_pos - cons_pos;
+}
+
/* Add extra RINGBUF maps to this ring buffer manager */
int ring_buffer__add(struct ring_buffer *rb, int map_fd,
ring_buffer_sample_fn sample_cb, void *ctx)
@@ -323,6 +332,30 @@ int ring_buffer__epoll_fd(const struct ring_buffer *rb)
return rb->epoll_fd;
}
+/* A userspace analogue to bpf_ringbuf_query for a particular ringbuffer index
+ * managed by this ringbuffer manager. Flags has the same arguments as
+ * bpf_ringbuf_query, and the index given is a 0-based index tracking the order
+ * the ringbuffers were added via ring_buffer__add. Returns the data requested
+ * according to flags.
+ */
+__u64 ring_buffer__query(struct ring_buffer *rb, unsigned int index, __u64 flags)
+{
+ struct ring *ring = &rb->rings[index];
+
+ switch (flags) {
+ case BPF_RB_AVAIL_DATA:
+ return ringbuf_avail_data_sz(ring);
+ case BPF_RB_RING_SIZE:
+ return ring->mask + 1;
+ case BPF_RB_CONS_POS:
+ return smp_load_acquire(ring->consumer_pos);
+ case BPF_RB_PROD_POS:
+ return smp_load_acquire(ring->producer_pos);
+ default:
+ return 0;
+ }
+}
+
static void user_ringbuf_unmap_ring(struct user_ring_buffer *rb)
{
if (rb->consumer_pos) {
--
2.34.1
