tools: Add xdrgen

Add a Python-based tool for translating XDR specifications into XDR
encoder and decoder functions written in the Linux kernel's C coding
style. The generator attempts to match the usual C coding style of
the Linux kernel's SunRPC consumers.

This approach is similar to the netlink code generator in
tools/net/ynl .

The maintainability benefits of machine-generated XDR code include:

- Stronger type checking
- Reduces the number of bugs introduced by human error
- Makes the XDR code easier to audit and analyze
- Enables rapid prototyping of new RPC-based protocols
- Hardens the layering between protocol logic and marshaling
- Makes it easier to add observability on demand
- Unit tests might be built for both the tool and (automatically)
  for the generated code

In addition, converting the XDR layer to use memory-safe languages
such as Rust will be easier if much of the code can be converted
automatically.

Tested-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

2 files changed, 269 insertions, 0 deletions

diff --git a/include/linux/sunrpc/xdrgen/_builtins.h b/include/linux/sunrpc/xdrgen/_builtins.h
new file mode 100644
index 000000000000..68746c59fc9a
--- /dev/null
+++ b/include/linux/sunrpc/xdrgen/_builtins.h
@@ -0,0 +1,243 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2024 Oracle and/or its affiliates.
+ *
+ * This header defines XDR data type primitives specified in
+ * Section 4 of RFC 4506, used by RPC programs implemented
+ * in the Linux kernel.
+ */
+
+#ifndef _SUNRPC_XDRGEN__BUILTINS_H_
+#define _SUNRPC_XDRGEN__BUILTINS_H_
+
+#include <linux/sunrpc/xdr.h>
+
+static inline bool
+xdrgen_decode_void(struct xdr_stream *xdr)
+{
+	return true;
+}
+
+static inline bool
+xdrgen_encode_void(struct xdr_stream *xdr)
+{
+	return true;
+}
+
+static inline bool
+xdrgen_decode_bool(struct xdr_stream *xdr, bool *ptr)
+{
+	__be32 *p = xdr_inline_decode(xdr, XDR_UNIT);
+
+	if (unlikely(!p))
+		return false;
+	*ptr = (*p != xdr_zero);
+	return true;
+}
+
+static inline bool
+xdrgen_encode_bool(struct xdr_stream *xdr, bool val)
+{
+	__be32 *p = xdr_reserve_space(xdr, XDR_UNIT);
+
+	if (unlikely(!p))
+		return false;
+	*p = val ? xdr_one : xdr_zero;
+	return true;
+}
+
+static inline bool
+xdrgen_decode_int(struct xdr_stream *xdr, s32 *ptr)
+{
+	__be32 *p = xdr_inline_decode(xdr, XDR_UNIT);
+
+	if (unlikely(!p))
+		return false;
+	*ptr = be32_to_cpup(p);
+	return true;
+}
+
+static inline bool
+xdrgen_encode_int(struct xdr_stream *xdr, s32 val)
+{
+	__be32 *p = xdr_reserve_space(xdr, XDR_UNIT);
+
+	if (unlikely(!p))
+		return false;
+	*p = cpu_to_be32(val);
+	return true;
+}
+
+static inline bool
+xdrgen_decode_unsigned_int(struct xdr_stream *xdr, u32 *ptr)
+{
+	__be32 *p = xdr_inline_decode(xdr, XDR_UNIT);
+
+	if (unlikely(!p))
+		return false;
+	*ptr = be32_to_cpup(p);
+	return true;
+}
+
+static inline bool
+xdrgen_encode_unsigned_int(struct xdr_stream *xdr, u32 val)
+{
+	__be32 *p = xdr_reserve_space(xdr, XDR_UNIT);
+
+	if (unlikely(!p))
+		return false;
+	*p = cpu_to_be32(val);
+	return true;
+}
+
+static inline bool
+xdrgen_decode_long(struct xdr_stream *xdr, s32 *ptr)
+{
+	__be32 *p = xdr_inline_decode(xdr, XDR_UNIT);
+
+	if (unlikely(!p))
+		return false;
+	*ptr = be32_to_cpup(p);
+	return true;
+}
+
+static inline bool
+xdrgen_encode_long(struct xdr_stream *xdr, s32 val)
+{
+	__be32 *p = xdr_reserve_space(xdr, XDR_UNIT);
+
+	if (unlikely(!p))
+		return false;
+	*p = cpu_to_be32(val);
+	return true;
+}
+
+static inline bool
+xdrgen_decode_unsigned_long(struct xdr_stream *xdr, u32 *ptr)
+{
+	__be32 *p = xdr_inline_decode(xdr, XDR_UNIT);
+
+	if (unlikely(!p))
+		return false;
+	*ptr = be32_to_cpup(p);
+	return true;
+}
+
+static inline bool
+xdrgen_encode_unsigned_long(struct xdr_stream *xdr, u32 val)
+{
+	__be32 *p = xdr_reserve_space(xdr, XDR_UNIT);
+
+	if (unlikely(!p))
+		return false;
+	*p = cpu_to_be32(val);
+	return true;
+}
+
+static inline bool
+xdrgen_decode_hyper(struct xdr_stream *xdr, s64 *ptr)
+{
+	__be32 *p = xdr_inline_decode(xdr, XDR_UNIT * 2);
+
+	if (unlikely(!p))
+		return false;
+	*ptr = get_unaligned_be64(p);
+	return true;
+}
+
+static inline bool
+xdrgen_encode_hyper(struct xdr_stream *xdr, s64 val)
+{
+	__be32 *p = xdr_reserve_space(xdr, XDR_UNIT * 2);
+
+	if (unlikely(!p))
+		return false;
+	put_unaligned_be64(val, p);
+	return true;
+}
+
+static inline bool
+xdrgen_decode_unsigned_hyper(struct xdr_stream *xdr, u64 *ptr)
+{
+	__be32 *p = xdr_inline_decode(xdr, XDR_UNIT * 2);
+
+	if (unlikely(!p))
+		return false;
+	*ptr = get_unaligned_be64(p);
+	return true;
+}
+
+static inline bool
+xdrgen_encode_unsigned_hyper(struct xdr_stream *xdr, u64 val)
+{
+	__be32 *p = xdr_reserve_space(xdr, XDR_UNIT * 2);
+
+	if (unlikely(!p))
+		return false;
+	put_unaligned_be64(val, p);
+	return true;
+}
+
+static inline bool
+xdrgen_decode_string(struct xdr_stream *xdr, string *ptr, u32 maxlen)
+{
+	__be32 *p;
+	u32 len;
+
+	if (unlikely(xdr_stream_decode_u32(xdr, &len) != XDR_UNIT))
+		return false;
+	if (unlikely(maxlen && len > maxlen))
+		return false;
+	if (len != 0) {
+		p = xdr_inline_decode(xdr, len);
+		if (unlikely(!p))
+			return false;
+		ptr->data = (unsigned char *)p;
+	}
+	ptr->len = len;
+	return true;
+}
+
+static inline bool
+xdrgen_encode_string(struct xdr_stream *xdr, string val, u32 maxlen)
+{
+	__be32 *p = xdr_reserve_space(xdr, XDR_UNIT + xdr_align_size(val.len));
+
+	if (unlikely(!p))
+		return false;
+	xdr_encode_opaque(p, val.data, val.len);
+	return true;
+}
+
+static inline bool
+xdrgen_decode_opaque(struct xdr_stream *xdr, opaque *ptr, u32 maxlen)
+{
+	__be32 *p;
+	u32 len;
+
+	if (unlikely(xdr_stream_decode_u32(xdr, &len) != XDR_UNIT))
+		return false;
+	if (unlikely(maxlen && len > maxlen))
+		return false;
+	if (len != 0) {
+		p = xdr_inline_decode(xdr, len);
+		if (unlikely(!p))
+			return false;
+		ptr->data = (u8 *)p;
+	}
+	ptr->len = len;
+	return true;
+}
+
+static inline bool
+xdrgen_encode_opaque(struct xdr_stream *xdr, opaque val)
+{
+	__be32 *p = xdr_reserve_space(xdr, XDR_UNIT + xdr_align_size(val.len));
+
+	if (unlikely(!p))
+		return false;
+	xdr_encode_opaque(p, val.data, val.len);
+	return true;
+}
+
+#endif /* _SUNRPC_XDRGEN__BUILTINS_H_ */
diff --git a/include/linux/sunrpc/xdrgen/_defs.h b/include/linux/sunrpc/xdrgen/_defs.h
new file mode 100644
index 000000000000..be9e62371758
--- /dev/null
+++ b/include/linux/sunrpc/xdrgen/_defs.h
@@ -0,0 +1,26 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2024 Oracle and/or its affiliates.
+ *
+ * This header defines XDR data type primitives specified in
+ * Section 4 of RFC 4506, used by RPC programs implemented
+ * in the Linux kernel.
+ */
+
+#ifndef _SUNRPC_XDRGEN__DEFS_H_
+#define _SUNRPC_XDRGEN__DEFS_H_
+
+#define TRUE	(true)
+#define FALSE	(false)
+
+typedef struct {
+	u32 len;
+	unsigned char *data;
+} string;
+
+typedef struct {
+	u32 len;
+	u8 *data;
+} opaque;
+
+#endif /* _SUNRPC_XDRGEN__DEFS_H_ */