BPF_KPTR_PERCPU_REF represents a percpu field type like below
struct val_t {
... fields ...
};
struct t {
...
struct val_t __percpu *percpu_data_ptr;
...
};
where
#define __percpu __attribute__((btf_type_tag("percpu")))
While BPF_KPTR_REF points to a trusted kernel object or a trusted
local object, BPF_KPTR_PERCPU_REF points to a trusted local
percpu object.
This patch added basic support for BPF_KPTR_PERCPU_REF
related to percpu field parsing, recording and free operations.
BPF_KPTR_PERCPU_REF also supports the same map types
as BPF_KPTR_REF does.
Note that unlike a local kptr, it is possible that
a BPF_KTPR_PERCUP_REF struct may not contain any
special fields like other kptr, bpf_spin_lock, bpf_list_head, etc.
Signed-off-by: Yonghong Song <yonghong.song@xxxxxxxxx>
---
include/linux/bpf.h | 18 ++++++++++++------
kernel/bpf/btf.c | 5 +++++
kernel/bpf/syscall.c | 7 ++++++-
3 files changed, 23 insertions(+), 7 deletions(-)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 60e80e90c37d..e6348fd0a785 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -180,14 +180,15 @@ enum btf_field_type {
BPF_TIMER = (1 << 1),
BPF_KPTR_UNREF = (1 << 2),
BPF_KPTR_REF = (1 << 3),
- BPF_KPTR = BPF_KPTR_UNREF | BPF_KPTR_REF,
- BPF_LIST_HEAD = (1 << 4),
- BPF_LIST_NODE = (1 << 5),
- BPF_RB_ROOT = (1 << 6),
- BPF_RB_NODE = (1 << 7),
+ BPF_KPTR_PERCPU_REF = (1 << 4),
+ BPF_KPTR = BPF_KPTR_UNREF | BPF_KPTR_REF | BPF_KPTR_PERCPU_REF,
+ BPF_LIST_HEAD = (1 << 5),
+ BPF_LIST_NODE = (1 << 6),
+ BPF_RB_ROOT = (1 << 7),
+ BPF_RB_NODE = (1 << 8),
BPF_GRAPH_NODE_OR_ROOT = BPF_LIST_NODE | BPF_LIST_HEAD |
BPF_RB_NODE | BPF_RB_ROOT,
- BPF_REFCOUNT = (1 << 8),
+ BPF_REFCOUNT = (1 << 9),
};
typedef void (*btf_dtor_kfunc_t)(void *);
@@ -300,6 +301,8 @@ static inline const char *btf_field_type_name(enum btf_field_type type)
case BPF_KPTR_UNREF:
case BPF_KPTR_REF:
return "kptr";
+ case BPF_KPTR_PERCPU_REF:
+ return "kptr_percpu";
case BPF_LIST_HEAD:
return "bpf_list_head";
case BPF_LIST_NODE:
@@ -325,6 +328,7 @@ static inline u32 btf_field_type_size(enum btf_field_type type)
return sizeof(struct bpf_timer);
case BPF_KPTR_UNREF:
case BPF_KPTR_REF:
+ case BPF_KPTR_PERCPU_REF:
return sizeof(u64);
case BPF_LIST_HEAD:
return sizeof(struct bpf_list_head);
@@ -351,6 +355,7 @@ static inline u32 btf_field_type_align(enum btf_field_type type)
return __alignof__(struct bpf_timer);
case BPF_KPTR_UNREF:
case BPF_KPTR_REF:
+ case BPF_KPTR_PERCPU_REF:
return __alignof__(u64);
case BPF_LIST_HEAD:
return __alignof__(struct bpf_list_head);
@@ -389,6 +394,7 @@ static inline void bpf_obj_init_field(const struct btf_field *field, void *addr)
case BPF_TIMER:
case BPF_KPTR_UNREF:
case BPF_KPTR_REF:
+ case BPF_KPTR_PERCPU_REF:
break;
default:
WARN_ON_ONCE(1);
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 249657c466dd..bc1792edc64e 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -3293,6 +3293,8 @@ static int btf_find_kptr(const struct btf *btf, const struct btf_type *t,
type = BPF_KPTR_UNREF;
else if (!strcmp("kptr", __btf_name_by_offset(btf, t->name_off)))
type = BPF_KPTR_REF;
+ else if (!strcmp("percpu", __btf_name_by_offset(btf, t->name_off)))
+ type = BPF_KPTR_PERCPU_REF;
else
return -EINVAL;
@@ -3457,6 +3459,7 @@ static int btf_find_struct_field(const struct btf *btf,
break;
case BPF_KPTR_UNREF:
case BPF_KPTR_REF:
+ case BPF_KPTR_PERCPU_REF:
ret = btf_find_kptr(btf, member_type, off, sz,
idx < info_cnt ? &info[idx] : &tmp);
if (ret < 0)
@@ -3523,6 +3526,7 @@ static int btf_find_datasec_var(const struct btf *btf, const struct btf_type *t,
break;
case BPF_KPTR_UNREF:
case BPF_KPTR_REF:
+ case BPF_KPTR_PERCPU_REF:
ret = btf_find_kptr(btf, var_type, off, sz,
idx < info_cnt ? &info[idx] : &tmp);
if (ret < 0)
@@ -3783,6 +3787,7 @@ struct btf_record *btf_parse_fields(const struct btf *btf, const struct btf_type
break;
case BPF_KPTR_UNREF:
case BPF_KPTR_REF:
+ case BPF_KPTR_PERCPU_REF:
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 7f4e8c357a6a..1c30b6ee84d4 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -514,6 +514,7 @@ void btf_record_free(struct btf_record *rec)
switch (rec->fields[i].type) {
case BPF_KPTR_UNREF:
case BPF_KPTR_REF:
+ case BPF_KPTR_PERCPU_REF:
if (rec->fields[i].kptr.module)
module_put(rec->fields[i].kptr.module);
btf_put(rec->fields[i].kptr.btf);
@@ -560,6 +561,7 @@ struct btf_record *btf_record_dup(const struct btf_record *rec)
switch (fields[i].type) {
case BPF_KPTR_UNREF:
case BPF_KPTR_REF:
+ case BPF_KPTR_PERCPU_REF:
btf_get(fields[i].kptr.btf);
if (fields[i].kptr.module && !try_module_get(fields[i].kptr.module)) {
ret = -ENXIO;
@@ -650,6 +652,7 @@ void bpf_obj_free_fields(const struct btf_record *rec, void *obj)
WRITE_ONCE(*(u64 *)field_ptr, 0);
break;
case BPF_KPTR_REF:
+ case BPF_KPTR_PERCPU_REF:
xchgd_field = (void *)xchg((unsigned long *)field_ptr, 0);
if (!xchgd_field)
break;
@@ -657,7 +660,8 @@ void bpf_obj_free_fields(const struct btf_record *rec, void *obj)
if (!btf_is_kernel(field->kptr.btf)) {
pointee_struct_meta = btf_find_struct_meta(field->kptr.btf,
field->kptr.btf_id);
- WARN_ON_ONCE(!pointee_struct_meta);
+ if (field->type != BPF_KPTR_PERCPU_REF)
+ WARN_ON_ONCE(!pointee_struct_meta);
migrate_disable();
__bpf_obj_drop_impl(xchgd_field, pointee_struct_meta ?
pointee_struct_meta->record :
@@ -1046,6 +1050,7 @@ static int map_check_btf(struct bpf_map *map, const struct btf *btf,
break;
case BPF_KPTR_UNREF:
case BPF_KPTR_REF:
+ case BPF_KPTR_PERCPU_REF:
case BPF_REFCOUNT:
if (map->map_type != BPF_MAP_TYPE_HASH &&
map->map_type != BPF_MAP_TYPE_PERCPU_HASH &&
--
2.34.1
