helpers: make few bpf helpers public

Make bpf_dynptr_slice_rdwr, bpf_dynptr_check_off_len and
__bpf_dynptr_write available outside of the helpers.c by
adding their prototypes into linux/include/bpf.h.
bpf_dynptr_check_off_len() implementation is moved to header and made
inline explicitly, as small function should typically be inlined.

These functions are going to be used from bpf_trace.c in the next
patch of this series.

Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
Link: https://lore.kernel.org/r/20250512205348.191079-2-mykyta.yatsenko5@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

2 files changed, 16 insertions, 12 deletions

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 3f0cc89c0622..83c56f40842b 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1349,6 +1349,20 @@ u32 __bpf_dynptr_size(const struct bpf_dynptr_kern *ptr);
 const void *__bpf_dynptr_data(const struct bpf_dynptr_kern *ptr, u32 len);
 void *__bpf_dynptr_data_rw(const struct bpf_dynptr_kern *ptr, u32 len);
 bool __bpf_dynptr_is_rdonly(const struct bpf_dynptr_kern *ptr);
+int __bpf_dynptr_write(const struct bpf_dynptr_kern *dst, u32 offset,
+		       void *src, u32 len, u64 flags);
+void *bpf_dynptr_slice_rdwr(const struct bpf_dynptr *p, u32 offset,
+			    void *buffer__opt, u32 buffer__szk);
+
+static inline int bpf_dynptr_check_off_len(const struct bpf_dynptr_kern *ptr, u32 offset, u32 len)
+{
+	u32 size = __bpf_dynptr_size(ptr);
+
+	if (len > size || offset > size - len)
+		return -E2BIG;
+
+	return 0;
+}
 
 #ifdef CONFIG_BPF_JIT
 int bpf_trampoline_link_prog(struct bpf_tramp_link *link,
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index fed53da75025..c96cc6aeae99 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -1714,16 +1714,6 @@ void bpf_dynptr_set_null(struct bpf_dynptr_kern *ptr)
 	memset(ptr, 0, sizeof(*ptr));
 }
 
-static int bpf_dynptr_check_off_len(const struct bpf_dynptr_kern *ptr, u32 offset, u32 len)
-{
-	u32 size = __bpf_dynptr_size(ptr);
-
-	if (len > size || offset > size - len)
-		return -E2BIG;
-
-	return 0;
-}
-
 BPF_CALL_4(bpf_dynptr_from_mem, void *, data, u32, size, u64, flags, struct bpf_dynptr_kern *, ptr)
 {
 	int err;
@@ -1810,8 +1800,8 @@ static const struct bpf_func_proto bpf_dynptr_read_proto = {
 	.arg5_type	= ARG_ANYTHING,
 };
 
-static int __bpf_dynptr_write(const struct bpf_dynptr_kern *dst, u32 offset, void *src,
-			      u32 len, u64 flags)
+int __bpf_dynptr_write(const struct bpf_dynptr_kern *dst, u32 offset, void *src,
+		       u32 len, u64 flags)
 {
 	enum bpf_dynptr_type type;
 	int err;