[bpf-next,v2,05/13] libbpf: Add helpers for bpf_dynptr_user

Commit Message

Hou Tao Sept. 24, 2022, 1:36 p.m. UTC

From: Hou Tao <[e-mail]>

Add bpf_dynptr_user_init() to initialize a bpf_dynptr,
bpf_dynptr_user_get_{data,size}() to get the address and length of
dynptr, and bpf_dynptr_user_trim() to trim size of dynptr.

Instead of exporting these symbols, simply adding these helpers as
inline functions in bpf.h.

Signed-off-by: Hou Tao <[e-mail]>
---
 tools/lib/bpf/bpf.h | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

Patch

diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
index 9c50beabdd14..6b91a8c2b2ae 100644
--- a/tools/lib/bpf/bpf.h
+++ b/tools/lib/bpf/bpf.h
@@ -371,6 +371,35 @@  LIBBPF_API int bpf_btf_get_fd_by_id(__u32 id);
 LIBBPF_API int bpf_link_get_fd_by_id(__u32 id);
 LIBBPF_API int bpf_obj_get_info_by_fd(int bpf_fd, void *info, __u32 *info_len);
 
+/* sys_bpf() will check the validity of size */
+static inline void bpf_dynptr_user_init(void *data, __u32 size,
+					struct bpf_dynptr_user *dynptr)
+{
+	/* Zero padding bytes */
+	memset(dynptr, 0, sizeof(*dynptr));
+	dynptr->data = (__u64)(unsigned long)data;
+	dynptr->size = size;
+}
+
+static inline __u32
+bpf_dynptr_user_get_size(const struct bpf_dynptr_user *dynptr)
+{
+	return dynptr->size;
+}
+
+static inline void *
+bpf_dynptr_user_get_data(const struct bpf_dynptr_user *dynptr)
+{
+	return (void *)(unsigned long)dynptr->data;
+}
+
+static inline void bpf_dynptr_user_trim(struct bpf_dynptr_user *dynptr,
+					__u32 new_size)
+{
+	if (new_size < dynptr->size)
+		dynptr->size = new_size;
+}
+
 struct bpf_prog_query_opts {
 	size_t sz; /* size of this struct for forward/backward compatibility */
 	__u32 query_flags;