[RFC bpf-next 1/5] bpf: Parse and support "kptr_user" tag.

[Kui-Feng Lee <thinker.li@xxxxxxxxx>]

Parse "kptr_user" tag from BTF, map it to BPF_KPTR_USER, and support it in
related functions.

Signed-off-by: Kui-Feng Lee <thinker.li@xxxxxxxxx>
---
 include/linux/bpf.h  | 8 +++++++-
 kernel/bpf/btf.c     | 5 +++++
 kernel/bpf/syscall.c | 2 ++
 3 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index b9425e410bcb..87d5f98249e2 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -194,7 +194,6 @@ enum btf_field_type {
 	BPF_KPTR_UNREF = (1 << 2),
 	BPF_KPTR_REF   = (1 << 3),
 	BPF_KPTR_PERCPU = (1 << 4),
-	BPF_KPTR       = BPF_KPTR_UNREF | BPF_KPTR_REF | BPF_KPTR_PERCPU,
 	BPF_LIST_HEAD  = (1 << 5),
 	BPF_LIST_NODE  = (1 << 6),
 	BPF_RB_ROOT    = (1 << 7),
@@ -203,6 +202,8 @@ enum btf_field_type {
 	BPF_GRAPH_ROOT = BPF_RB_ROOT | BPF_LIST_HEAD,
 	BPF_REFCOUNT   = (1 << 9),
 	BPF_WORKQUEUE  = (1 << 10),
+	BPF_KPTR_USER  = (1 << 11),
+	BPF_KPTR       = BPF_KPTR_UNREF | BPF_KPTR_REF | BPF_KPTR_PERCPU | BPF_KPTR_USER,
 };
 
 typedef void (*btf_dtor_kfunc_t)(void *);
@@ -322,6 +323,8 @@ static inline const char *btf_field_type_name(enum btf_field_type type)
 		return "kptr";
 	case BPF_KPTR_PERCPU:
 		return "percpu_kptr";
+	case BPF_KPTR_USER:
+		return "user_kptr";
 	case BPF_LIST_HEAD:
 		return "bpf_list_head";
 	case BPF_LIST_NODE:
@@ -350,6 +353,7 @@ static inline u32 btf_field_type_size(enum btf_field_type type)
 	case BPF_KPTR_UNREF:
 	case BPF_KPTR_REF:
 	case BPF_KPTR_PERCPU:
+	case BPF_KPTR_USER:
 		return sizeof(u64);
 	case BPF_LIST_HEAD:
 		return sizeof(struct bpf_list_head);
@@ -379,6 +383,7 @@ static inline u32 btf_field_type_align(enum btf_field_type type)
 	case BPF_KPTR_UNREF:
 	case BPF_KPTR_REF:
 	case BPF_KPTR_PERCPU:
+	case BPF_KPTR_USER:
 		return __alignof__(u64);
 	case BPF_LIST_HEAD:
 		return __alignof__(struct bpf_list_head);
@@ -419,6 +424,7 @@ static inline void bpf_obj_init_field(const struct btf_field *field, void *addr)
 	case BPF_KPTR_UNREF:
 	case BPF_KPTR_REF:
 	case BPF_KPTR_PERCPU:
+	case BPF_KPTR_USER:
 		break;
 	default:
 		WARN_ON_ONCE(1);
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 95426d5b634e..3b0f555fbbe6 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -3361,6 +3361,8 @@ static int btf_find_kptr(const struct btf *btf, const struct btf_type *t,
 		type = BPF_KPTR_REF;
 	else if (!strcmp("percpu_kptr", __btf_name_by_offset(btf, t->name_off)))
 		type = BPF_KPTR_PERCPU;
+	else if (!strcmp("kptr_user", __btf_name_by_offset(btf, t->name_off)))
+		type = BPF_KPTR_USER;
 	else
 		return -EINVAL;
 
@@ -3538,6 +3540,7 @@ static int btf_repeat_fields(struct btf_field_info *info,
 		case BPF_KPTR_UNREF:
 		case BPF_KPTR_REF:
 		case BPF_KPTR_PERCPU:
+		case BPF_KPTR_USER:
 		case BPF_LIST_HEAD:
 		case BPF_RB_ROOT:
 			break;
@@ -3664,6 +3667,7 @@ static int btf_find_field_one(const struct btf *btf,
 	case BPF_KPTR_UNREF:
 	case BPF_KPTR_REF:
 	case BPF_KPTR_PERCPU:
+	case BPF_KPTR_USER:
 		ret = btf_find_kptr(btf, var_type, off, sz,
 				    info_cnt ? &info[0] : &tmp);
 		if (ret < 0)
@@ -3988,6 +3992,7 @@ struct btf_record *btf_parse_fields(const struct btf *btf, const struct btf_type
 		case BPF_KPTR_UNREF:
 		case BPF_KPTR_REF:
 		case BPF_KPTR_PERCPU:
+		case BPF_KPTR_USER:
 			ret = btf_parse_kptr(btf, &rec->fields[i], &info_arr[i]);
 			if (ret < 0)
 				goto end;
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index bf6c5f685ea2..90a25307480e 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -548,6 +548,7 @@ void btf_record_free(struct btf_record *rec)
 		case BPF_KPTR_UNREF:
 		case BPF_KPTR_REF:
 		case BPF_KPTR_PERCPU:
+		case BPF_KPTR_USER:
 			if (rec->fields[i].kptr.module)
 				module_put(rec->fields[i].kptr.module);
 			btf_put(rec->fields[i].kptr.btf);
@@ -596,6 +597,7 @@ struct btf_record *btf_record_dup(const struct btf_record *rec)
 		case BPF_KPTR_UNREF:
 		case BPF_KPTR_REF:
 		case BPF_KPTR_PERCPU:
+		case BPF_KPTR_USER:
 			btf_get(fields[i].kptr.btf);
 			if (fields[i].kptr.module && !try_module_get(fields[i].kptr.module)) {
 				ret = -ENXIO;
-- 
2.34.1