From: Hou Tao <houtao1@xxxxxxxxxx>
Add helper btf_find_dynptr() to check whether or not the passed btf type
is bpf_dynptr. It can be extend to find an embedded dynptr in passed btf
type if needed later.
It will be used by bpf map (e.g. qp-trie) with bpf_dynptr key.
Signed-off-by: Hou Tao <houtao1@xxxxxxxxxx>
---
include/linux/btf.h | 1 +
kernel/bpf/btf.c | 13 +++++++++++++
2 files changed, 14 insertions(+)
diff --git a/include/linux/btf.h b/include/linux/btf.h
index f9aababc5d78..5bf508c2bad2 100644
--- a/include/linux/btf.h
+++ b/include/linux/btf.h
@@ -165,6 +165,7 @@ int btf_find_spin_lock(const struct btf *btf, const struct btf_type *t);
int btf_find_timer(const struct btf *btf, const struct btf_type *t);
struct bpf_map_value_off *btf_parse_kptrs(const struct btf *btf,
const struct btf_type *t);
+int btf_find_dynptr(const struct btf *btf, const struct btf_type *t);
bool btf_type_is_void(const struct btf_type *t);
s32 btf_find_by_name_kind(const struct btf *btf, const char *name, u8 kind);
const struct btf_type *btf_type_skip_modifiers(const struct btf *btf,
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index a44ad4b347ff..fefbe84c6998 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -3522,6 +3522,19 @@ struct bpf_map_value_off *btf_parse_kptrs(const struct btf *btf,
return ERR_PTR(ret);
}
+/* Now only allow to use 'struct bpf_dynptr' as map key.
+ * Map key with embedded bpf_dynptr is not allowed.
+ */
+int btf_find_dynptr(const struct btf *btf, const struct btf_type *t)
+{
+ /* Only allow struct type */
+ if (__btf_type_is_struct(t) && t->size == sizeof(struct bpf_dynptr) &&
+ !strcmp("bpf_dynptr", __btf_name_by_offset(btf, t->name_off)))
+ return 0;
+
+ return -EINVAL;
+}
+
static void __btf_struct_show(const struct btf *btf, const struct btf_type *t,
u32 type_id, void *data, u8 bits_offset,
struct btf_show *show)
--
2.29.2
