From: jhb <jhb@FreeBSD.org>
Date: Thu, 29 Oct 2015 21:25:46 +0000 (+0000)
Subject: Use movw instead of movl (or plain mov) when moving segment registers
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=727afb6dcdbec7ebcfef37be2fe578c7bc74ac39;p=people%2Fjulieng%2Ffreebsd.git

Use movw instead of movl (or plain mov) when moving segment registers
into memory.  This is a nop on clang's assembler, but some assemblers
complain if the size suffix is incorrect.

Submitted by:	bde
---

diff --git a/sys/i386/i386/exception.s b/sys/i386/i386/exception.s
index 70c6d9d00758..f91f51612269 100644
--- a/sys/i386/i386/exception.s
+++ b/sys/i386/i386/exception.s
@@ -158,11 +158,11 @@ IDTVEC(xmm)
 alltraps:
 	pushal
 	pushl	$0
-	movl	%ds,(%esp)
+	movw	%ds,(%esp)
 	pushl	$0
-	movl	%es,(%esp)
+	movw	%es,(%esp)
 	pushl	$0
-	movl	%fs,(%esp)
+	movw	%fs,(%esp)
 alltraps_with_regs_pushed:
 	SET_KERNEL_SREGS
 	cld
@@ -237,11 +237,11 @@ IDTVEC(lcall_syscall)
 	subl	$4,%esp			/* skip over tf_trapno */
 	pushal
 	pushl	$0
-	movl	%ds,(%esp)
+	movw	%ds,(%esp)
 	pushl	$0
-	movl	%es,(%esp)
+	movw	%es,(%esp)
 	pushl	$0
-	movl	%fs,(%esp)
+	movw	%fs,(%esp)
 	SET_KERNEL_SREGS
 	cld
 	FAKE_MCOUNT(TF_EIP(%esp))
@@ -266,11 +266,11 @@ IDTVEC(int0x80_syscall)
 	subl	$4,%esp			/* skip over tf_trapno */
 	pushal
 	pushl	$0
-	movl	%ds,(%esp)
+	movw	%ds,(%esp)
 	pushl	$0
-	movl	%es,(%esp)
+	movw	%es,(%esp)
 	pushl	$0
-	movl	%fs,(%esp)
+	movw	%fs,(%esp)
 	SET_KERNEL_SREGS
 	cld
 	FAKE_MCOUNT(TF_EIP(%esp))
@@ -426,15 +426,15 @@ doreti_iret_fault:
 	subl	$8,%esp
 	pushal
 	pushl	$0
-	movl	%ds,(%esp)
+	movw	%ds,(%esp)
 	.globl	doreti_popl_ds_fault
 doreti_popl_ds_fault:
 	pushl	$0
-	movl	%es,(%esp)
+	movw	%es,(%esp)
 	.globl	doreti_popl_es_fault
 doreti_popl_es_fault:
 	pushl	$0
-	movl	%fs,(%esp)
+	movw	%fs,(%esp)
 	.globl	doreti_popl_fs_fault
 doreti_popl_fs_fault:
 	sti
diff --git a/sys/i386/include/asmacros.h b/sys/i386/include/asmacros.h
index 91c25f725dfa..d14f0794dc0f 100644
--- a/sys/i386/include/asmacros.h
+++ b/sys/i386/include/asmacros.h
@@ -147,11 +147,11 @@
 	pushl	$0 ;		/* dummy trap type */			\
 	pushal ;		/* 8 ints */				\
 	pushl	$0 ;		/* save data and extra segments ... */	\
-	mov	%ds,(%esp) ;						\
+	movw	%ds,(%esp) ;						\
 	pushl	$0 ;							\
-	mov	%es,(%esp) ;						\
+	movw	%es,(%esp) ;						\
 	pushl	$0 ;							\
-	mov	%fs,(%esp)
+	movw	%fs,(%esp)
 	
 #define	POP_FRAME							\
 	popl	%fs ;							\