Merge branch 'compiler_types-add-endianness-dependent-__counted_by_-le-be'

Alexander Lobakin says:

====================
compiler_types: add Endianness-dependent __counted_by_{le,be}

Some structures contain flexible arrays at the end and the counter for
them, but the counter has explicit Endianness and thus __counted_by()
can't be used directly.

To increase test coverage for potential problems without breaking
anything, introduce __counted_by_{le,be} defined depending on platform's
Endianness to either __counted_by() when applicable or noop otherwise.
The first user will be virtchnl2.h from idpf just as example with 9 flex
structures having Little Endian counters.

Maybe it would be a good idea to introduce such attributes on compiler
level if possible, but for now let's stop on what we have.
====================

Link: https://lore.kernel.org/r/20240327142241.1745989-1-aleksander.lobakin@intel.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Documentation/conf.py

@@ -75,6 +75,8 @@ if major >= 3:
             "__rcu",
             "__user",
             "__force",
+            "__counted_by_le",
+            "__counted_by_be",
 
             # include/linux/compiler_attributes.h:
             "__alias",

drivers/net/ethernet/intel/idpf/idpf_txrx.h

@@ -8,6 +8,8 @@
 #include <net/tcp.h>
 #include <net/netdev_queues.h>
 
+#include "virtchnl2_lan_desc.h"
+
 #define IDPF_LARGE_MAX_Q			256
 #define IDPF_MAX_Q				16
 #define IDPF_MIN_Q				2

drivers/net/ethernet/intel/idpf/virtchnl2.h

@@ -4,6 +4,8 @@
 #ifndef _VIRTCHNL2_H_
 #define _VIRTCHNL2_H_
 
+#include <linux/if_ether.h>
+
 /* All opcodes associated with virtchnl2 are prefixed with virtchnl2 or
  * VIRTCHNL2. Any future opcodes, offloads/capabilities, structures,
  * and defines must be prefixed with virtchnl2 or VIRTCHNL2 to avoid confusion.
@@ -17,8 +19,6 @@
  * must remain unchanged over time, so we specify explicit values for all enums.
  */
 
-#include "virtchnl2_lan_desc.h"
-
 /* This macro is used to generate compilation errors if a structure
  * is not exactly the correct length.
  */
@@ -555,7 +555,7 @@ VIRTCHNL2_CHECK_STRUCT_LEN(32, virtchnl2_queue_reg_chunk);
 struct virtchnl2_queue_reg_chunks {
 	__le16 num_chunks;
 	u8 pad[6];
-	struct virtchnl2_queue_reg_chunk chunks[];
+	struct virtchnl2_queue_reg_chunk chunks[] __counted_by_le(num_chunks);
 };
 VIRTCHNL2_CHECK_STRUCT_LEN(8, virtchnl2_queue_reg_chunks);
 
@@ -703,7 +703,7 @@ struct virtchnl2_config_tx_queues {
 	__le32 vport_id;
 	__le16 num_qinfo;
 	u8 pad[10];
-	struct virtchnl2_txq_info qinfo[];
+	struct virtchnl2_txq_info qinfo[] __counted_by_le(num_qinfo);
 };
 VIRTCHNL2_CHECK_STRUCT_LEN(16, virtchnl2_config_tx_queues);
 
@@ -782,7 +782,7 @@ struct virtchnl2_config_rx_queues {
 	__le32 vport_id;
 	__le16 num_qinfo;
 	u8 pad[18];
-	struct virtchnl2_rxq_info qinfo[];
+	struct virtchnl2_rxq_info qinfo[] __counted_by_le(num_qinfo);
 };
 VIRTCHNL2_CHECK_STRUCT_LEN(24, virtchnl2_config_rx_queues);
 
@@ -868,7 +868,7 @@ VIRTCHNL2_CHECK_STRUCT_LEN(32, virtchnl2_vector_chunk);
 struct virtchnl2_vector_chunks {
 	__le16 num_vchunks;
 	u8 pad[14];
-	struct virtchnl2_vector_chunk vchunks[];
+	struct virtchnl2_vector_chunk vchunks[] __counted_by_le(num_vchunks);
 };
 VIRTCHNL2_CHECK_STRUCT_LEN(16, virtchnl2_vector_chunks);
 
@@ -912,7 +912,7 @@ struct virtchnl2_rss_lut {
 	__le16 lut_entries_start;
 	__le16 lut_entries;
 	u8 pad[4];
-	__le32 lut[];
+	__le32 lut[] __counted_by_le(lut_entries);
 };
 VIRTCHNL2_CHECK_STRUCT_LEN(12, virtchnl2_rss_lut);
 
@@ -977,7 +977,7 @@ struct virtchnl2_ptype {
 	u8 ptype_id_8;
 	u8 proto_id_count;
 	__le16 pad;
-	__le16 proto_id[];
+	__le16 proto_id[] __counted_by(proto_id_count);
 } __packed __aligned(2);
 VIRTCHNL2_CHECK_STRUCT_LEN(6, virtchnl2_ptype);
 
@@ -1104,7 +1104,7 @@ struct virtchnl2_rss_key {
 	__le32 vport_id;
 	__le16 key_len;
 	u8 pad;
-	u8 key_flex[];
+	u8 key_flex[] __counted_by_le(key_len);
 } __packed;
 VIRTCHNL2_CHECK_STRUCT_LEN(7, virtchnl2_rss_key);
 
@@ -1131,7 +1131,7 @@ VIRTCHNL2_CHECK_STRUCT_LEN(16, virtchnl2_queue_chunk);
 struct virtchnl2_queue_chunks {
 	__le16 num_chunks;
 	u8 pad[6];
-	struct virtchnl2_queue_chunk chunks[];
+	struct virtchnl2_queue_chunk chunks[] __counted_by_le(num_chunks);
 };
 VIRTCHNL2_CHECK_STRUCT_LEN(8, virtchnl2_queue_chunks);
 
@@ -1195,7 +1195,7 @@ struct virtchnl2_queue_vector_maps {
 	__le32 vport_id;
 	__le16 num_qv_maps;
 	u8 pad[10];
-	struct virtchnl2_queue_vector qv_maps[];
+	struct virtchnl2_queue_vector qv_maps[] __counted_by_le(num_qv_maps);
 };
 VIRTCHNL2_CHECK_STRUCT_LEN(16, virtchnl2_queue_vector_maps);
 
@@ -1247,7 +1247,7 @@ struct virtchnl2_mac_addr_list {
 	__le32 vport_id;
 	__le16 num_mac_addr;
 	u8 pad[2];
-	struct virtchnl2_mac_addr mac_addr_list[];
+	struct virtchnl2_mac_addr mac_addr_list[] __counted_by_le(num_mac_addr);
 };
 VIRTCHNL2_CHECK_STRUCT_LEN(8, virtchnl2_mac_addr_list);
 

include/linux/compiler_types.h

@@ -282,6 +282,17 @@ struct ftrace_likely_data {
 #define __no_sanitize_or_inline __always_inline
 #endif
 
+/*
+ * Apply __counted_by() when the Endianness matches to increase test coverage.
+ */
+#ifdef __LITTLE_ENDIAN
+#define __counted_by_le(member)	__counted_by(member)
+#define __counted_by_be(member)
+#else
+#define __counted_by_le(member)
+#define __counted_by_be(member)	__counted_by(member)
+#endif
+
 /* Do not trap wrapping arithmetic within an annotated function. */
 #ifdef CONFIG_UBSAN_SIGNED_WRAP
 # define __signed_wrap __attribute__((no_sanitize("signed-integer-overflow")))

scripts/kernel-doc

@@ -1143,6 +1143,7 @@ sub dump_struct($$) {
         $members =~ s/\s*$attribute/ /gi;
         $members =~ s/\s*__aligned\s*\([^;]*\)/ /gos;
         $members =~ s/\s*__counted_by\s*\([^;]*\)/ /gos;
+        $members =~ s/\s*__counted_by_(le|be)\s*\([^;]*\)/ /gos;
         $members =~ s/\s*__packed\s*/ /gos;
         $members =~ s/\s*CRYPTO_MINALIGN_ATTR/ /gos;
         $members =~ s/\s*____cacheline_aligned_in_smp/ /gos;