linux-kernel - [PATCH v2 14/15] x86/lib/memmove_64.S: Convert memmove() to ALTERNATIVE macro

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Date:	Tue, 24 Feb 2015 12:14:56 +0100
From:	Borislav Petkov <bp@...en8.de>
To:	X86 ML <x86@...nel.org>
Cc:	Andy Lutomirski <luto@...capital.net>,
	LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH v2 14/15] x86/lib/memmove_64.S: Convert memmove() to ALTERNATIVE macro

From: Borislav Petkov <bp@...e.de>

Make it execute the ERMS version if support is present and we're in the
forward memmove() part and remove the unfolded alternatives section
definition.

Signed-off-by: Borislav Petkov <bp@...e.de>
---
 arch/x86/lib/memmove_64.S | 19 ++-----------------
 1 file changed, 2 insertions(+), 17 deletions(-)

diff --git a/arch/x86/lib/memmove_64.S b/arch/x86/lib/memmove_64.S
index bbfa6b269ece..0f8a0d0331b9 100644
--- a/arch/x86/lib/memmove_64.S
+++ b/arch/x86/lib/memmove_64.S
@@ -5,7 +5,6 @@
  * This assembly file is re-written from memmove_64.c file.
  *	- Copyright 2011 Fenghua Yu <fenghua.yu@...el.com>
  */
-#define _STRING_C
 #include <linux/linkage.h>
 #include <asm/dwarf2.h>
 #include <asm/cpufeature.h>
@@ -44,6 +43,8 @@ ENTRY(__memmove)
 	jg 2f
 
 .Lmemmove_begin_forward:
+	ALTERNATIVE "", "movq %rdx, %rcx; rep movsb; retq", X86_FEATURE_ERMS
+
 	/*
 	 * movsq instruction have many startup latency
 	 * so we handle small size by general register.
@@ -207,21 +208,5 @@ ENTRY(__memmove)
 13:
 	retq
 	CFI_ENDPROC
-
-	.section .altinstr_replacement,"ax"
-.Lmemmove_begin_forward_efs:
-	/* Forward moving data. */
-	movq %rdx, %rcx
-	rep movsb
-	retq
-.Lmemmove_end_forward_efs:
-	.previous
-
-	.section .altinstructions,"a"
-	altinstruction_entry .Lmemmove_begin_forward,		\
-		.Lmemmove_begin_forward_efs,X86_FEATURE_ERMS,	\
-		.Lmemmove_end_forward-.Lmemmove_begin_forward,	\
-		.Lmemmove_end_forward_efs-.Lmemmove_begin_forward_efs,0
-	.previous
 ENDPROC(__memmove)
 ENDPROC(memmove)
-- 
2.2.0.33.gc18b867

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