x86, reloc: Use xorl instead of xorq in relocate_kernel_64.S

There is no point in using "xorq" to clear a register... use "xorl" to
clear the bottom 32 bits, and the upper 32 bits get cleared by virtue
of zero extension.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: Kees Cook <keescook@chromium.org>
Link: http://lkml.kernel.org/n/tip-b76zi1gep39c0zs8fbvkhie9@git.kernel.org

arch/x86/kernel/relocate_kernel_64.S

@@ -151,21 +151,21 @@ identity_mapped:
 
 	testq	%r11, %r11
 	jnz 1f
-	xorq	%rax, %rax
-	xorq	%rbx, %rbx
-	xorq    %rcx, %rcx
-	xorq    %rdx, %rdx
-	xorq    %rsi, %rsi
-	xorq    %rdi, %rdi
-	xorq    %rbp, %rbp
-	xorq	%r8,  %r8
-	xorq	%r9,  %r9
-	xorq	%r10, %r10
-	xorq	%r11, %r11
-	xorq	%r12, %r12
-	xorq	%r13, %r13
-	xorq	%r14, %r14
-	xorq	%r15, %r15
+	xorl	%eax, %eax
+	xorl	%ebx, %ebx
+	xorl    %ecx, %ecx
+	xorl    %edx, %edx
+	xorl    %esi, %esi
+	xorl    %edi, %edi
+	xorl    %ebp, %ebp
+	xorl	%r8d, %r8d
+	xorl	%r9d, %r9d
+	xorl	%r10d, %r10d
+	xorl	%r11d, %r11d
+	xorl	%r12d, %r12d
+	xorl	%r13d, %r13d
+	xorl	%r14d, %r14d
+	xorl	%r15d, %r15d
 
 	ret
 
@@ -212,8 +212,8 @@ virtual_mapped:
 	/* Do the copies */
 swap_pages:
 	movq	%rdi, %rcx 	/* Put the page_list in %rcx */
-	xorq	%rdi, %rdi
-	xorq	%rsi, %rsi
+	xorl	%edi, %edi
+	xorl	%esi, %esi
 	jmp	1f
 
 0:	/* top, read another word for the indirection page */