bpf: Add support to retrieve ref_ctr_offset for uprobe perf link

Adding support to retrieve ref_ctr_offset for uprobe perf link,
which got somehow omitted from the initial uprobe link info changes.

Signed-off-by: Jiri Olsa <[email protected]>
Signed-off-by: Andrii Nakryiko <[email protected]>
Acked-by: Yafang Shao <[email protected]>
Link: https://lore.kernel.org/bpf/[email protected]

Author: olsajiri

include/uapi/linux/bpf.h

@@ -6724,6 +6724,7 @@ struct bpf_link_info {
 					__u32 name_len;
 					__u32 offset; /* offset from file_name */
 					__u64 cookie;
+					__u64 ref_ctr_offset;
 				} uprobe; /* BPF_PERF_EVENT_UPROBE, BPF_PERF_EVENT_URETPROBE */
 				struct {
 					__aligned_u64 func_name; /* in/out */

kernel/bpf/syscall.c

@@ -3800,14 +3800,14 @@ static int bpf_perf_link_fill_kprobe(const struct perf_event *event,
 static int bpf_perf_link_fill_uprobe(const struct perf_event *event,
 				     struct bpf_link_info *info)
 {
+	u64 ref_ctr_offset, offset;
 	char __user *uname;
-	u64 addr, offset;
 	u32 ulen, type;
 	int err;
 
 	uname = u64_to_user_ptr(info->perf_event.uprobe.file_name);
 	ulen = info->perf_event.uprobe.name_len;
-	err = bpf_perf_link_fill_common(event, uname, &ulen, &offset, &addr,
+	err = bpf_perf_link_fill_common(event, uname, &ulen, &offset, &ref_ctr_offset,
 					&type, NULL);
 	if (err)
 		return err;
@@ -3819,6 +3819,7 @@ static int bpf_perf_link_fill_uprobe(const struct perf_event *event,
 	info->perf_event.uprobe.name_len = ulen;
 	info->perf_event.uprobe.offset = offset;
 	info->perf_event.uprobe.cookie = event->bpf_cookie;
+	info->perf_event.uprobe.ref_ctr_offset = ref_ctr_offset;
 	return 0;
 }
 #endif

kernel/trace/trace_uprobe.c

@@ -1489,7 +1489,7 @@ int bpf_get_uprobe_info(const struct perf_event *event, u32 *fd_type,
 				    : BPF_FD_TYPE_UPROBE;
 	*filename = tu->filename;
 	*probe_offset = tu->offset;
-	*probe_addr = 0;
+	*probe_addr = tu->ref_ctr_offset;
 	return 0;
 }
 #endif	/* CONFIG_PERF_EVENTS */

tools/include/uapi/linux/bpf.h

@@ -6724,6 +6724,7 @@ struct bpf_link_info {
 					__u32 name_len;
 					__u32 offset; /* offset from file_name */
 					__u64 cookie;
+					__u64 ref_ctr_offset;
 				} uprobe; /* BPF_PERF_EVENT_UPROBE, BPF_PERF_EVENT_URETPROBE */
 				struct {
 					__aligned_u64 func_name; /* in/out */