[PATCH v2 1/3] x86: Use MOVL when reading segment registers

[Uros Bizjak]

Use MOVL when reading segment registers to avoid 0x66 operand-size
override insn prefix. The segment value is always 16-bit and gets
zero-extended to the full 32-bit size.

Signed-off-by: Uros Bizjak <ubizjak@xxxxxxxxx>
Tested-by: Michael Kelley <mhklinux@xxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
---
 arch/x86/include/asm/segment.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/segment.h b/arch/x86/include/asm/segment.h
index f59ae7186940..9f5be2bbd291 100644
--- a/arch/x86/include/asm/segment.h
+++ b/arch/x86/include/asm/segment.h
@@ -348,7 +348,7 @@ static inline void __loadsegment_fs(unsigned short value)
  * Save a segment register away:
  */
 #define savesegment(seg, value)				\
-	asm("mov %%" #seg ",%0":"=r" (value) : : "memory")
+	asm("movl %%" #seg ",%k0" : "=r" (value) : : "memory")
 
 #endif /* !__ASSEMBLER__ */
 #endif /* __KERNEL__ */
-- 
2.51.1