bpf: btf: Clean up btf.h in uapi

This patch cleans up btf.h in uapi:
1) Rename "name" to "name_off" to better reflect it is an offset to the
   string section instead of a char array.
2) Remove unused value BTF_FLAGS_COMPR and BTF_MAGIC_SWAP

Suggested-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

include/uapi/linux/btf.h

@@ -6,9 +6,7 @@
 #include <linux/types.h>
 
 #define BTF_MAGIC	0xeB9F
-#define BTF_MAGIC_SWAP	0x9FeB
 #define BTF_VERSION	1
-#define BTF_FLAGS_COMPR	0x01
 
 struct btf_header {
 	__u16	magic;
@@ -43,7 +41,7 @@ struct btf_header {
 #define BTF_STR_OFFSET(ref)	((ref) & BTF_MAX_NAME_OFFSET)
 
 struct btf_type {
-	__u32 name;
+	__u32 name_off;
 	/* "info" bits arrangement
 	 * bits  0-15: vlen (e.g. # of struct's members)
 	 * bits 16-23: unused
@@ -105,7 +103,7 @@ struct btf_type {
  * info in "struct btf_type").
  */
 struct btf_enum {
-	__u32	name;
+	__u32	name_off;
 	__s32	val;
 };
 
@@ -122,7 +120,7 @@ struct btf_array {
  * "struct btf_type").
  */
 struct btf_member {
-	__u32	name;
+	__u32	name_off;
 	__u32	type;
 	__u32	offset;	/* offset in bits */
 };

kernel/bpf/btf.c

@@ -473,7 +473,7 @@ __printf(4, 5) static void __btf_verifier_log_type(struct btf_verifier_env *env,
 	__btf_verifier_log(log, "[%u] %s %s%s",
 			   env->log_type_id,
 			   btf_kind_str[kind],
-			   btf_name_by_offset(btf, t->name),
+			   btf_name_by_offset(btf, t->name_off),
 			   log_details ? " " : "");
 
 	if (log_details)
@@ -517,7 +517,7 @@ static void btf_verifier_log_member(struct btf_verifier_env *env,
 		btf_verifier_log_type(env, struct_type, NULL);
 
 	__btf_verifier_log(log, "\t%s type_id=%u bits_offset=%u",
-			   btf_name_by_offset(btf, member->name),
+			   btf_name_by_offset(btf, member->name_off),
 			   member->type, member->offset);
 
 	if (fmt && *fmt) {
@@ -1419,10 +1419,10 @@ static s32 btf_struct_check_meta(struct btf_verifier_env *env,
 	btf_verifier_log_type(env, t, NULL);
 
 	for_each_member(i, t, member) {
-		if (!btf_name_offset_valid(btf, member->name)) {
+		if (!btf_name_offset_valid(btf, member->name_off)) {
 			btf_verifier_log_member(env, t, member,
 						"Invalid member name_offset:%u",
-						member->name);
+						member->name_off);
 			return -EINVAL;
 		}
 
@@ -1605,14 +1605,14 @@ static s32 btf_enum_check_meta(struct btf_verifier_env *env,
 	btf_verifier_log_type(env, t, NULL);
 
 	for (i = 0; i < nr_enums; i++) {
-		if (!btf_name_offset_valid(btf, enums[i].name)) {
+		if (!btf_name_offset_valid(btf, enums[i].name_off)) {
 			btf_verifier_log(env, "\tInvalid name_offset:%u",
-					 enums[i].name);
+					 enums[i].name_off);
 			return -EINVAL;
 		}
 
 		btf_verifier_log(env, "\t%s val=%d\n",
-				 btf_name_by_offset(btf, enums[i].name),
+				 btf_name_by_offset(btf, enums[i].name_off),
 				 enums[i].val);
 	}
 
@@ -1636,7 +1636,7 @@ static void btf_enum_seq_show(const struct btf *btf, const struct btf_type *t,
 	for (i = 0; i < nr_enums; i++) {
 		if (v == enums[i].val) {
 			seq_printf(m, "%s",
-				   btf_name_by_offset(btf, enums[i].name));
+				   btf_name_by_offset(btf, enums[i].name_off));
 			return;
 		}
 	}
@@ -1687,9 +1687,9 @@ static s32 btf_check_meta(struct btf_verifier_env *env,
 		return -EINVAL;
 	}
 
-	if (!btf_name_offset_valid(env->btf, t->name)) {
+	if (!btf_name_offset_valid(env->btf, t->name_off)) {
 		btf_verifier_log(env, "[%u] Invalid name_offset:%u",
-				 env->log_type_id, t->name);
+				 env->log_type_id, t->name_off);
 		return -EINVAL;
 	}
 

tools/include/uapi/linux/btf.h

@@ -6,9 +6,7 @@
 #include <linux/types.h>
 
 #define BTF_MAGIC	0xeB9F
-#define BTF_MAGIC_SWAP	0x9FeB
 #define BTF_VERSION	1
-#define BTF_FLAGS_COMPR	0x01
 
 struct btf_header {
 	__u16	magic;
@@ -43,7 +41,7 @@ struct btf_header {
 #define BTF_STR_OFFSET(ref)	((ref) & BTF_MAX_NAME_OFFSET)
 
 struct btf_type {
-	__u32 name;
+	__u32 name_off;
 	/* "info" bits arrangement
 	 * bits  0-15: vlen (e.g. # of struct's members)
 	 * bits 16-23: unused
@@ -105,7 +103,7 @@ struct btf_type {
  * info in "struct btf_type").
  */
 struct btf_enum {
-	__u32	name;
+	__u32	name_off;
 	__s32	val;
 };
 
@@ -122,7 +120,7 @@ struct btf_array {
  * "struct btf_type").
  */
 struct btf_member {
-	__u32	name;
+	__u32	name_off;
 	__u32	type;
 	__u32	offset;	/* offset in bits */
 };

tools/lib/bpf/btf.c

@@ -281,7 +281,7 @@ int32_t btf__find_by_name(const struct btf *btf, const char *type_name)
 
 	for (i = 1; i <= btf->nr_types; i++) {
 		const struct btf_type *t = btf->types[i];
-		const char *name = btf_name_by_offset(btf, t->name);
+		const char *name = btf_name_by_offset(btf, t->name_off);
 
 		if (name && !strcmp(type_name, name))
 			return i;