bpf: Store ref_ctr_offsets values in bpf_uprobe array

We will need to return ref_ctr_offsets values through link_info
interface in following change, so we need to keep them around.

Storing ref_ctr_offsets values directly into bpf_uprobe array.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/bpf/20231125193130.834322-3-jolsa@kernel.org

kernel/trace/bpf_trace.c

@@ -3033,6 +3033,7 @@ struct bpf_uprobe_multi_link;
 struct bpf_uprobe {
 	struct bpf_uprobe_multi_link *link;
 	loff_t offset;
+	unsigned long ref_ctr_offset;
 	u64 cookie;
 	struct uprobe_consumer consumer;
 };
@@ -3172,7 +3173,6 @@ int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
 {
 	struct bpf_uprobe_multi_link *link = NULL;
 	unsigned long __user *uref_ctr_offsets;
-	unsigned long *ref_ctr_offsets = NULL;
 	struct bpf_link_primer link_primer;
 	struct bpf_uprobe *uprobes = NULL;
 	struct task_struct *task = NULL;
@@ -3245,18 +3245,12 @@ int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
 	if (!uprobes || !link)
 		goto error_free;
 
-	if (uref_ctr_offsets) {
-		ref_ctr_offsets = kvcalloc(cnt, sizeof(*ref_ctr_offsets), GFP_KERNEL);
-		if (!ref_ctr_offsets)
-			goto error_free;
-	}
-
 	for (i = 0; i < cnt; i++) {
 		if (ucookies && __get_user(uprobes[i].cookie, ucookies + i)) {
 			err = -EFAULT;
 			goto error_free;
 		}
-		if (uref_ctr_offsets && __get_user(ref_ctr_offsets[i], uref_ctr_offsets + i)) {
+		if (uref_ctr_offsets && __get_user(uprobes[i].ref_ctr_offset, uref_ctr_offsets + i)) {
 			err = -EFAULT;
 			goto error_free;
 		}
@@ -3287,7 +3281,7 @@ int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
 	for (i = 0; i < cnt; i++) {
 		err = uprobe_register_refctr(d_real_inode(link->path.dentry),
 					     uprobes[i].offset,
-					     ref_ctr_offsets ? ref_ctr_offsets[i] : 0,
+					     uprobes[i].ref_ctr_offset,
 					     &uprobes[i].consumer);
 		if (err) {
 			bpf_uprobe_unregister(&path, uprobes, i);
@@ -3299,11 +3293,9 @@ int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
 	if (err)
 		goto error_free;
 
-	kvfree(ref_ctr_offsets);
 	return bpf_link_settle(&link_primer);
 
 error_free:
-	kvfree(ref_ctr_offsets);
 	kvfree(uprobes);
 	kfree(link);
 	if (task)