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Date:      Fri, 17 Apr 2020 15:19:43 +0000 (UTC)
From:      Conrad Meyer <cem@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r360044 - head/sys/amd64/include
Message-ID:  <202004171519.03HFJhb5009977@repo.freebsd.org>
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Author: cem
Date: Fri Apr 17 15:19:42 2020
New Revision: 360044
URL: https://svnweb.freebsd.org/changeset/base/360044

Log:
  vmm.h: Add ABI assertions and mark implicit holes
  
  The static assertions were added (with size and offsets from gdb) and verified
  with a build prior to marking the holes explicitly.
  
  This is in preparation for a subsequent revision, pending in phabricator, that
  makes use of some of these unused bits without impacting the ABI.
  
  Reviewed by:	grehan
  Differential Revision:	https://reviews.freebsd.org/D24461

Modified:
  head/sys/amd64/include/vmm.h

Modified: head/sys/amd64/include/vmm.h
==============================================================================
--- head/sys/amd64/include/vmm.h	Fri Apr 17 14:57:15 2020	(r360043)
+++ head/sys/amd64/include/vmm.h	Fri Apr 17 15:19:42 2020	(r360044)
@@ -515,6 +515,8 @@ struct vie_op {
 	uint8_t		op_type;	/* type of operation (e.g. MOV) */
 	uint16_t	op_flags;
 };
+_Static_assert(sizeof(struct vie_op) == 4, "ABI");
+_Static_assert(_Alignof(struct vie_op) == 2, "ABI");
 
 #define	VIE_INST_SIZE	15
 struct vie {
@@ -539,13 +541,17 @@ struct vie {
 			rm:4;
 
 	uint8_t		ss:2,			/* SIB byte */
-			index:4,
-			base:4;
+			_sparebits:2,
+			index:4,		/* SIB byte */
+			base:4;			/* SIB byte */
 
 	uint8_t		disp_bytes;
 	uint8_t		imm_bytes;
 
 	uint8_t		scale;
+
+	uint8_t		_sparebytes[3];
+
 	int		base_register;		/* VM_REG_GUEST_xyz */
 	int		index_register;		/* VM_REG_GUEST_xyz */
 	int		segment_register;	/* VM_REG_GUEST_xyz */
@@ -555,8 +561,14 @@ struct vie {
 
 	uint8_t		decoded;	/* set to 1 if successfully decoded */
 
+	uint8_t		_sparebyte;
+
 	struct vie_op	op;			/* opcode description */
 };
+_Static_assert(sizeof(struct vie) == 64, "ABI");
+_Static_assert(__offsetof(struct vie, disp_bytes) == 22, "ABI");
+_Static_assert(__offsetof(struct vie, scale) == 24, "ABI");
+_Static_assert(__offsetof(struct vie, base_register) == 28, "ABI");
 
 enum vm_exitcode {
 	VM_EXITCODE_INOUT,

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