[PATCH bpf-next v6 2/4] bpf: Handle bpf_link_info for the parameterized task BPF iterators.

[Kui-Feng Lee <kuifeng@fb.com>]

Add new fields to bpf_link_info that users can query it through
bpf_obj_get_info_by_fd().

Signed-off-by: Kui-Feng Lee <kuifeng@fb.com>
---
 include/uapi/linux/bpf.h       |  6 ++++++
 kernel/bpf/task_iter.c         | 18 ++++++++++++++++++
 tools/include/uapi/linux/bpf.h |  6 ++++++
 3 files changed, 30 insertions(+)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 778fbf11aa00..6647e052dd00 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -6170,6 +6170,12 @@ struct bpf_link_info {
 					__u32 map_id;
 				} map;
 			};
+			union {
+				struct {
+					__u32 tid;
+					__u32 pid;
+				} task;
+			};
 		} iter;
 		struct  {
 			__u32 netns_ino;
diff --git a/kernel/bpf/task_iter.c b/kernel/bpf/task_iter.c
index 2f5fc6602917..927b3a1cf354 100644
--- a/kernel/bpf/task_iter.c
+++ b/kernel/bpf/task_iter.c
@@ -596,6 +596,21 @@ static const struct bpf_iter_seq_info task_seq_info = {
 	.seq_priv_size		= sizeof(struct bpf_iter_seq_task_info),
 };
 
+static int bpf_iter_fill_link_info(const struct bpf_iter_aux_info *aux, struct bpf_link_info *info)
+{
+	switch (aux->task.type) {
+	case BPF_TASK_ITER_TID:
+		info->iter.task.tid = aux->task.pid;
+		break;
+	case BPF_TASK_ITER_TGID:
+		info->iter.task.pid = aux->task.pid;
+		break;
+	default:
+		break;
+	}
+	return 0;
+}
+
 static struct bpf_iter_reg task_reg_info = {
 	.target			= "task",
 	.attach_target		= bpf_iter_attach_task,
@@ -606,6 +621,7 @@ static struct bpf_iter_reg task_reg_info = {
 		  PTR_TO_BTF_ID_OR_NULL },
 	},
 	.seq_info		= &task_seq_info,
+	.fill_link_info		= bpf_iter_fill_link_info,
 };
 
 static const struct bpf_iter_seq_info task_file_seq_info = {
@@ -627,6 +643,7 @@ static struct bpf_iter_reg task_file_reg_info = {
 		  PTR_TO_BTF_ID_OR_NULL },
 	},
 	.seq_info		= &task_file_seq_info,
+	.fill_link_info		= bpf_iter_fill_link_info,
 };
 
 static const struct bpf_iter_seq_info task_vma_seq_info = {
@@ -648,6 +665,7 @@ static struct bpf_iter_reg task_vma_reg_info = {
 		  PTR_TO_BTF_ID_OR_NULL },
 	},
 	.seq_info		= &task_vma_seq_info,
+	.fill_link_info		= bpf_iter_fill_link_info,
 };
 
 BPF_CALL_5(bpf_find_vma, struct task_struct *, task, u64, start,
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 7a0268749a48..177722c5dd62 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -6170,6 +6170,12 @@ struct bpf_link_info {
 					__u32 map_id;
 				} map;
 			};
+			union {
+				struct {
+					__u32 tid;
+					__u32 pid;
+				} task;
+			};
 		} iter;
 		struct  {
 			__u32 netns_ino;
-- 
2.30.2