linux-kernel - [PATCH v3 4/5] ARM: use unified assembler in c files

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Message-Id: <a0aa512943024821fae210854b89ac0f430f388a.1550001435.git.stefan@agner.ch>
Date:   Tue, 12 Feb 2019 21:02:00 +0100
From:   Stefan Agner <stefan@...er.ch>
To:     linux@...linux.org.uk
Cc:     ndesaulniers@...gle.com, natechancellor@...il.com, arnd@...db.de,
        ard.biesheuvel@...aro.org, nicolas.pitre@...aro.org,
        thierry.reding@...il.com, will.deacon@....com,
        julien.thierry@....com, mark.rutland@....com,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        Stefan Agner <stefan@...er.ch>, Nicolas Pitre <nico@...aro.org>
Subject: [PATCH v3 4/5] ARM: use unified assembler in c files

Use unified assembler syntax (UAL) in inline assembler. Divided
syntax is considered deprecated. This will also allow to build
the kernel using LLVM's integrated assembler.

When compiling non-Thumb2 GCC always emits a ".syntax divided"
at the beginning of the inline assembly which makes the
assembler fail. Since GCC 5 there is the -masm-syntax-unified
GCC option which make GCC assume unified syntax asm and hence
emits ".syntax unified" even in ARM mode. However, the option
is broken since GCC version 6 (see GCC PR88648 [1]). Work
around by adding ".syntax unified" as part of the inline
assembly.

[0] https://gcc.gnu.org/onlinedocs/gcc/ARM-Options.html#index-masm-syntax-unified
[1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88648

Signed-off-by: Stefan Agner <stefan@...er.ch>
Acked-by: Nicolas Pitre <nico@...aro.org>
---
Changes in v2:
- Force unified syntax for inline assembler using .syntax unified
Changes in v3:
- Describe reason for adding ".syntax unified"

 arch/arm/mm/copypage-v4mc.c | 3 ++-
 arch/arm/mm/copypage-v4wb.c | 3 ++-
 arch/arm/mm/copypage-v4wt.c | 3 ++-
 3 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/arch/arm/mm/copypage-v4mc.c b/arch/arm/mm/copypage-v4mc.c
index b03202cddddb..f74cdce6d4da 100644
--- a/arch/arm/mm/copypage-v4mc.c
+++ b/arch/arm/mm/copypage-v4mc.c
@@ -45,6 +45,7 @@ static void mc_copy_user_page(void *from, void *to)
 	int tmp;
 
 	asm volatile ("\
+	.syntax unified\n\
 	ldmia	%0!, {r2, r3, ip, lr}		@ 4\n\
 1:	mcr	p15, 0, %1, c7, c6, 1		@ 1   invalidate D line\n\
 	stmia	%1!, {r2, r3, ip, lr}		@ 4\n\
@@ -56,7 +57,7 @@ static void mc_copy_user_page(void *from, void *to)
 	ldmia	%0!, {r2, r3, ip, lr}		@ 4\n\
 	subs	%2, %2, #1			@ 1\n\
 	stmia	%1!, {r2, r3, ip, lr}		@ 4\n\
-	ldmneia	%0!, {r2, r3, ip, lr}		@ 4\n\
+	ldmiane	%0!, {r2, r3, ip, lr}		@ 4\n\
 	bne	1b				@ "
 	: "+&r" (from), "+&r" (to), "=&r" (tmp)
 	: "2" (PAGE_SIZE / 64)
diff --git a/arch/arm/mm/copypage-v4wb.c b/arch/arm/mm/copypage-v4wb.c
index cd3e165afeed..6d336740aae4 100644
--- a/arch/arm/mm/copypage-v4wb.c
+++ b/arch/arm/mm/copypage-v4wb.c
@@ -27,6 +27,7 @@ static void v4wb_copy_user_page(void *kto, const void *kfrom)
 	int tmp;
 
 	asm volatile ("\
+	.syntax unified\n\
 	ldmia	%1!, {r3, r4, ip, lr}		@ 4\n\
 1:	mcr	p15, 0, %0, c7, c6, 1		@ 1   invalidate D line\n\
 	stmia	%0!, {r3, r4, ip, lr}		@ 4\n\
@@ -38,7 +39,7 @@ static void v4wb_copy_user_page(void *kto, const void *kfrom)
 	ldmia	%1!, {r3, r4, ip, lr}		@ 4\n\
 	subs	%2, %2, #1			@ 1\n\
 	stmia	%0!, {r3, r4, ip, lr}		@ 4\n\
-	ldmneia	%1!, {r3, r4, ip, lr}		@ 4\n\
+	ldmiane	%1!, {r3, r4, ip, lr}		@ 4\n\
 	bne	1b				@ 1\n\
 	mcr	p15, 0, %1, c7, c10, 4		@ 1   drain WB"
 	: "+&r" (kto), "+&r" (kfrom), "=&r" (tmp)
diff --git a/arch/arm/mm/copypage-v4wt.c b/arch/arm/mm/copypage-v4wt.c
index 8614572e1296..3851bb396442 100644
--- a/arch/arm/mm/copypage-v4wt.c
+++ b/arch/arm/mm/copypage-v4wt.c
@@ -25,6 +25,7 @@ static void v4wt_copy_user_page(void *kto, const void *kfrom)
 	int tmp;
 
 	asm volatile ("\
+	.syntax unified\n\
 	ldmia	%1!, {r3, r4, ip, lr}		@ 4\n\
 1:	stmia	%0!, {r3, r4, ip, lr}		@ 4\n\
 	ldmia	%1!, {r3, r4, ip, lr}		@ 4+1\n\
@@ -34,7 +35,7 @@ static void v4wt_copy_user_page(void *kto, const void *kfrom)
 	ldmia	%1!, {r3, r4, ip, lr}		@ 4\n\
 	subs	%2, %2, #1			@ 1\n\
 	stmia	%0!, {r3, r4, ip, lr}		@ 4\n\
-	ldmneia	%1!, {r3, r4, ip, lr}		@ 4\n\
+	ldmiane	%1!, {r3, r4, ip, lr}		@ 4\n\
 	bne	1b				@ 1\n\
 	mcr	p15, 0, %2, c7, c7, 0		@ flush ID cache"
 	: "+&r" (kto), "+&r" (kfrom), "=&r" (tmp)
-- 
2.20.1