linux-kernel - [PATCH 8/9] x86/asm: replace MOVQ $imm,%reg with MOVL

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Date:	Tue, 31 Mar 2015 19:00:10 +0200
From:	Denys Vlasenko <dvlasenk@...hat.com>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	Denys Vlasenko <dvlasenk@...hat.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Borislav Petkov <bp@...en8.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	Andy Lutomirski <luto@...capital.net>,
	Oleg Nesterov <oleg@...hat.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Alexei Starovoitov <ast@...mgrid.com>,
	Will Drewry <wad@...omium.org>,
	Kees Cook <keescook@...omium.org>, x86@...nel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 8/9] x86/asm: replace MOVQ $imm,%reg with MOVL

There is no reason to use MOVQ to load a nonnegative immediate
into a 64-bit register. MOVL does the same, since upper 32 bits
are zero extended.

Signed-off-by: Denys Vlasenko <dvlasenk@...hat.com>
CC: Linus Torvalds <torvalds@...ux-foundation.org>
CC: Steven Rostedt <rostedt@...dmis.org>
CC: Ingo Molnar <mingo@...nel.org>
CC: Borislav Petkov <bp@...en8.de>
CC: "H. Peter Anvin" <hpa@...or.com>
CC: Andy Lutomirski <luto@...capital.net>
CC: Oleg Nesterov <oleg@...hat.com>
CC: Frederic Weisbecker <fweisbec@...il.com>
CC: Alexei Starovoitov <ast@...mgrid.com>
CC: Will Drewry <wad@...omium.org>
CC: Kees Cook <keescook@...omium.org>
CC: x86@...nel.org
CC: linux-kernel@...r.kernel.org
---
 arch/x86/crypto/crc32c-pcl-intel-asm_64.S | 2 +-
 arch/x86/crypto/twofish-x86_64-asm_64.S   | 4 ++--
 arch/x86/kernel/relocate_kernel_64.S      | 8 ++++----
 3 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/arch/x86/crypto/crc32c-pcl-intel-asm_64.S b/arch/x86/crypto/crc32c-pcl-intel-asm_64.S
index 26d49eb..225be06 100644
--- a/arch/x86/crypto/crc32c-pcl-intel-asm_64.S
+++ b/arch/x86/crypto/crc32c-pcl-intel-asm_64.S
@@ -178,7 +178,7 @@ continue_block:
 	## 2a) PROCESS FULL BLOCKS:
 	################################################################
 full_block:
-	movq    $128,%rax
+	movl    $128,%eax
 	lea     128*8*2(block_0), block_1
 	lea     128*8*3(block_0), block_2
 	add     $128*8*1, block_0
diff --git a/arch/x86/crypto/twofish-x86_64-asm_64.S b/arch/x86/crypto/twofish-x86_64-asm_64.S
index a039d21..a350c99 100644
--- a/arch/x86/crypto/twofish-x86_64-asm_64.S
+++ b/arch/x86/crypto/twofish-x86_64-asm_64.S
@@ -264,7 +264,7 @@ ENTRY(twofish_enc_blk)
 	movq	R1,	8(%rsi)
 
 	popq	R1
-	movq	$1,%rax
+	movl	$1,%eax
 	ret
 ENDPROC(twofish_enc_blk)
 
@@ -316,6 +316,6 @@ ENTRY(twofish_dec_blk)
 	movq	R1,	8(%rsi)
 
 	popq	R1
-	movq	$1,%rax
+	movl	$1,%eax
 	ret
 ENDPROC(twofish_dec_blk)
diff --git a/arch/x86/kernel/relocate_kernel_64.S b/arch/x86/kernel/relocate_kernel_64.S
index 04cb179..98111b3 100644
--- a/arch/x86/kernel/relocate_kernel_64.S
+++ b/arch/x86/kernel/relocate_kernel_64.S
@@ -123,7 +123,7 @@ identity_mapped:
 	 * Set cr4 to a known state:
 	 *  - physical address extension enabled
 	 */
-	movq	$X86_CR4_PAE, %rax
+	movl	$X86_CR4_PAE, %eax
 	movq	%rax, %cr4
 
 	jmp 1f
@@ -246,17 +246,17 @@ swap_pages:
 	movq	%rsi, %rax
 
 	movq	%r10, %rdi
-	movq	$512,   %rcx
+	movl	$512, %ecx
 	rep ; movsq
 
 	movq	%rax, %rdi
 	movq	%rdx, %rsi
-	movq	$512,   %rcx
+	movl	$512, %ecx
 	rep ; movsq
 
 	movq	%rdx, %rdi
 	movq	%r10, %rsi
-	movq	$512,   %rcx
+	movl	$512, %ecx
 	rep ; movsq
 
 	lea	PAGE_SIZE(%rax), %rsi
-- 
1.8.1.4

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