tools: ynl-gen: introduce support for bitfield32 attribute type

Introduce support for attribute type bitfield32.
Note that since the generated code works with struct nla_bitfield32,
the generator adds netlink.h to the list of includes for userspace
headers in case any bitfield32 is present.

Note that this is added only to genetlink-legacy scheme as requested
by Jakub Kicinski.

Signed-off-by: Jiri Pirko <jiri@nvidia.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://lore.kernel.org/r/20231021112711.660606-3-jiri@resnulli.us
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Documentation/netlink/genetlink-legacy.yaml

@@ -192,7 +192,7 @@ properties:
                 type: string
               type: &attr-type
                 description: The netlink attribute type
-                enum: [ unused, pad, flag, binary,
+                enum: [ unused, pad, flag, binary, bitfield32,
                         uint, sint, u8, u16, u32, u64, s32, s64,
                         string, nest, array-nest, nest-type-value ]
               doc:

Documentation/userspace-api/netlink/genetlink-legacy.rst

@@ -182,7 +182,7 @@ members
 
  - ``name`` - The attribute name of the struct member
  - ``type`` - One of the scalar types ``u8``, ``u16``, ``u32``, ``u64``, ``s8``,
-   ``s16``, ``s32``, ``s64``, ``string`` or ``binary``.
+   ``s16``, ``s32``, ``s64``, ``string``, ``binary`` or ``bitfield32``.
  - ``byte-order`` - ``big-endian`` or ``little-endian``
  - ``doc``, ``enum``, ``enum-as-flags``, ``display-hint`` - Same as for
    :ref:`attribute definitions <attribute_properties>`

tools/net/ynl/lib/ynl.c

@@ -379,6 +379,12 @@ int ynl_attr_validate(struct ynl_parse_arg *yarg, const struct nlattr *attr)
 		yerr(yarg->ys, YNL_ERROR_ATTR_INVALID,
 		     "Invalid attribute (string %s)", policy->name);
 		return -1;
+	case YNL_PT_BITFIELD32:
+		if (len == sizeof(struct nla_bitfield32))
+			break;
+		yerr(yarg->ys, YNL_ERROR_ATTR_INVALID,
+		     "Invalid attribute (bitfield32 %s)", policy->name);
+		return -1;
 	default:
 		yerr(yarg->ys, YNL_ERROR_ATTR_INVALID,
 		     "Invalid attribute (unknown %s)", policy->name);

tools/net/ynl/lib/ynl.h

@@ -135,6 +135,7 @@ enum ynl_policy_type {
 	YNL_PT_U64,
 	YNL_PT_UINT,
 	YNL_PT_NUL_STR,
+	YNL_PT_BITFIELD32,
 };
 
 struct ynl_policy_attr {

tools/net/ynl/lib/ynl.py

@@ -478,6 +478,8 @@ def _add_attr(self, space, name, value):
         elif attr['type'] in NlAttr.type_formats:
             format = NlAttr.get_format(attr['type'], attr.byte_order)
             attr_payload = format.pack(int(value))
+        elif attr['type'] in "bitfield32":
+            attr_payload = struct.pack("II", int(value["value"]), int(value["selector"]))
         else:
             raise Exception(f'Unknown type at {space} {name} {value} {attr["type"]}')
 
@@ -545,14 +547,19 @@ def _decode(self, attrs, space):
                 decoded = attr.as_auto_scalar(attr_spec['type'], attr_spec.byte_order)
             elif attr_spec["type"] in NlAttr.type_formats:
                 decoded = attr.as_scalar(attr_spec['type'], attr_spec.byte_order)
+                if 'enum' in attr_spec:
+                    decoded = self._decode_enum(decoded, attr_spec)
             elif attr_spec["type"] == 'array-nest':
                 decoded = self._decode_array_nest(attr, attr_spec)
+            elif attr_spec["type"] == 'bitfield32':
+                value, selector = struct.unpack("II", attr.raw)
+                if 'enum' in attr_spec:
+                    value = self._decode_enum(value, attr_spec)
+                    selector = self._decode_enum(selector, attr_spec)
+                decoded = {"value": value, "selector": selector}
             else:
                 raise Exception(f'Unknown {attr_spec["type"]} with name {attr_spec["name"]}')
 
-            if 'enum' in attr_spec:
-                decoded = self._decode_enum(decoded, attr_spec)
-
             if not attr_spec.is_multi:
                 rsp[attr_spec['name']] = decoded
             elif attr_spec.name in rsp:

tools/net/ynl/ynl-gen-c.py

@@ -488,6 +488,31 @@ def _setter_lines(self, ri, member, presence):
                 f'memcpy({member}, {self.c_name}, {presence}_len);']
 
 
+class TypeBitfield32(Type):
+    def _complex_member_type(self, ri):
+        return "struct nla_bitfield32"
+
+    def _attr_typol(self):
+        return f'.type = YNL_PT_BITFIELD32, '
+
+    def _attr_policy(self, policy):
+        if not 'enum' in self.attr:
+            raise Exception('Enum required for bitfield32 attr')
+        enum = self.family.consts[self.attr['enum']]
+        mask = enum.get_mask(as_flags=True)
+        return f"NLA_POLICY_BITFIELD32({mask})"
+
+    def attr_put(self, ri, var):
+        line = f"mnl_attr_put(nlh, {self.enum_name}, sizeof(struct nla_bitfield32), &{var}->{self.c_name})"
+        self._attr_put_line(ri, var, line)
+
+    def _attr_get(self, ri, var):
+        return f"memcpy(&{var}->{self.c_name}, mnl_attr_get_payload(attr), sizeof(struct nla_bitfield32));", None, None
+
+    def _setter_lines(self, ri, member, presence):
+        return [f"memcpy(&{member}, {self.c_name}, sizeof(struct nla_bitfield32));"]
+
+
 class TypeNest(Type):
     def _complex_member_type(self, ri):
         return self.nested_struct_type
@@ -786,6 +811,8 @@ def new_attr(self, elem, value):
             t = TypeString(self.family, self, elem, value)
         elif elem['type'] == 'binary':
             t = TypeBinary(self.family, self, elem, value)
+        elif elem['type'] == 'bitfield32':
+            t = TypeBitfield32(self.family, self, elem, value)
         elif elem['type'] == 'nest':
             t = TypeNest(self.family, self, elem, value)
         elif elem['type'] == 'array-nest':
@@ -2414,6 +2441,16 @@ def render_user_family(family, cw, prototype):
     cw.block_end(line=';')
 
 
+def family_contains_bitfield32(family):
+    for _, attr_set in family.attr_sets.items():
+        if attr_set.subset_of:
+            continue
+        for _, attr in attr_set.items():
+            if attr.type == "bitfield32":
+                return True
+    return False
+
+
 def find_kernel_root(full_path):
     sub_path = ''
     while True:
@@ -2499,6 +2536,8 @@ def main():
         cw.p('#include <string.h>')
         if args.header:
             cw.p('#include <linux/types.h>')
+            if family_contains_bitfield32(parsed):
+                cw.p('#include <linux/netlink.h>')
         else:
             cw.p(f'#include "{parsed.name}-user.h"')
             cw.p('#include "ynl.h"')