Merge branch 'btf-uapi-cleanups'

Martin KaFai Lau says:

====================
This patch set makes some changes to cleanup the unused
bits in BTF uapi.  It also makes the btf_header extensible.

Please see individual patches for details.

v2:
- Remove NR_SECS from patch 2
- Remove "unsigned" check on array->index_type from patch 3
- Remove BTF_INT_VARARGS and further limit BTF_INT_ENCODING
  from 8 bits to 4 bits in patch 4
- Adjustments in test_btf.c to reflect changes in v2
====================

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

1 files changed, 11 insertions, 26 deletions

diff --git a/tools/include/uapi/linux/btf.h b/tools/include/uapi/linux/btf.h
index bcb56ee47014..0b5ddbe135a4 100644
--- a/tools/include/uapi/linux/btf.h
+++ b/tools/include/uapi/linux/btf.h
@@ -12,42 +12,29 @@ struct btf_header {
 	__u16	magic;
 	__u8	version;
 	__u8	flags;
-
-	__u32	parent_label;
-	__u32	parent_name;
+	__u32	hdr_len;
 
 	/* All offsets are in bytes relative to the end of this header */
-	__u32	label_off;	/* offset of label section	*/
-	__u32	object_off;	/* offset of data object section*/
-	__u32	func_off;	/* offset of function section	*/
 	__u32	type_off;	/* offset of type section	*/
+	__u32	type_len;	/* length of type section	*/
 	__u32	str_off;	/* offset of string section	*/
 	__u32	str_len;	/* length of string section	*/
 };
 
 /* Max # of type identifier */
-#define BTF_MAX_TYPE	0x7fffffff
+#define BTF_MAX_TYPE	0x0000ffff
 /* Max offset into the string section */
-#define BTF_MAX_NAME_OFFSET	0x7fffffff
+#define BTF_MAX_NAME_OFFSET	0x0000ffff
 /* Max # of struct/union/enum members or func args */
 #define BTF_MAX_VLEN	0xffff
 
-/* The type id is referring to a parent BTF */
-#define BTF_TYPE_PARENT(id)	(((id) >> 31) & 0x1)
-#define BTF_TYPE_ID(id)		((id) & BTF_MAX_TYPE)
-
-/* String is in the ELF string section */
-#define BTF_STR_TBL_ELF_ID(ref)	(((ref) >> 31) & 0x1)
-#define BTF_STR_OFFSET(ref)	((ref) & BTF_MAX_NAME_OFFSET)
-
 struct btf_type {
 	__u32 name_off;
 	/* "info" bits arrangement
 	 * bits  0-15: vlen (e.g. # of struct's members)
 	 * bits 16-23: unused
-	 * bits 24-28: kind (e.g. int, ptr, array...etc)
-	 * bits 29-30: unused
-	 * bits    31: root
+	 * bits 24-27: kind (e.g. int, ptr, array...etc)
+	 * bits 28-31: unused
 	 */
 	__u32 info;
 	/* "size" is used by INT, ENUM, STRUCT and UNION.
@@ -62,8 +49,7 @@ struct btf_type {
 	};
 };
 
-#define BTF_INFO_KIND(info)	(((info) >> 24) & 0x1f)
-#define BTF_INFO_ISROOT(info)	(!!(((info) >> 24) & 0x80))
+#define BTF_INFO_KIND(info)	(((info) >> 24) & 0x0f)
 #define BTF_INFO_VLEN(info)	((info) & 0xffff)
 
 #define BTF_KIND_UNKN		0	/* Unknown	*/
@@ -88,15 +74,14 @@ struct btf_type {
 /* BTF_KIND_INT is followed by a u32 and the following
  * is the 32 bits arrangement:
  */
-#define BTF_INT_ENCODING(VAL)	(((VAL) & 0xff000000) >> 24)
+#define BTF_INT_ENCODING(VAL)	(((VAL) & 0x0f000000) >> 24)
 #define BTF_INT_OFFSET(VAL)	(((VAL  & 0x00ff0000)) >> 16)
 #define BTF_INT_BITS(VAL)	((VAL)  & 0x0000ffff)
 
 /* Attributes stored in the BTF_INT_ENCODING */
-#define BTF_INT_SIGNED	0x1
-#define BTF_INT_CHAR	0x2
-#define BTF_INT_BOOL	0x4
-#define BTF_INT_VARARGS	0x8
+#define BTF_INT_SIGNED	(1 << 0)
+#define BTF_INT_CHAR	(1 << 1)
+#define BTF_INT_BOOL	(1 << 2)
 
 /* BTF_KIND_ENUM is followed by multiple "struct btf_enum".
  * The exact number of btf_enum is stored in the vlen (of the