From: Nicolas Pitre nicolas.pitre@linaro.org
commit 75fea300d73ae5b18957949a53ec770daaeb6fc2 upstream.
The GNU assembler has implemented the "unified syntax" parsing since 2005. This "unified" syntax is required when the kernel is built in Thumb2 mode. However the "unified" syntax is a mixed bag of features, including not requiring a `#' prefix with immediate operands. This leads to situations where some code builds just fine in Thumb2 mode and fails to build in ARM mode if that prefix is missing. This behavior discrepancy makes build tests less valuable, forcing both ARM and Thumb2 builds for proper coverage.
Let's "fix" this issue by always using the "unified" syntax for both ARM and Thumb2 mode. Given that the documented minimum binutils version that properly builds the kernel is version 2.20 released in 2010, we can assume that any toolchain capable of building the latest kernel is also "unified syntax" capable.
Whith this, a bunch of macros used to mask some differences between both syntaxes can be removed, with the side effect of making LTO easier.
Suggested-by: Robin Murphy robin.murphy@arm.com Signed-off-by: Nicolas Pitre nico@linaro.org Signed-off-by: Russell King rmk+kernel@armlinux.org.uk [nathan: Resolve small conflict on 4.9 due to a lack of 494609701e06a] Signed-off-by: Nathan Chancellor nathan@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/arm/Kconfig | 7 --- arch/arm/Makefile | 6 ++- arch/arm/include/asm/unified.h | 77 +---------------------------------------- 3 files changed, 8 insertions(+), 82 deletions(-)
--- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -1546,12 +1546,10 @@ config THUMB2_KERNEL depends on (CPU_V7 || CPU_V7M) && !CPU_V6 && !CPU_V6K default y if CPU_THUMBONLY select AEABI - select ARM_ASM_UNIFIED select ARM_UNWIND help By enabling this option, the kernel will be compiled in - Thumb-2 mode. A compiler/assembler that understand the unified - ARM-Thumb syntax is needed. + Thumb-2 mode.
If unsure, say N.
@@ -1586,9 +1584,6 @@ config THUMB2_AVOID_R_ARM_THM_JUMP11
Unless you are sure your tools don't have this problem, say Y.
-config ARM_ASM_UNIFIED - bool - config ARM_PATCH_IDIV bool "Runtime patch udiv/sdiv instructions into __aeabi_{u}idiv()" depends on CPU_32v7 && !XIP_KERNEL --- a/arch/arm/Makefile +++ b/arch/arm/Makefile @@ -113,9 +113,11 @@ ifeq ($(CONFIG_ARM_UNWIND),y) CFLAGS_ABI +=-funwind-tables endif
+# Accept old syntax despite ".syntax unified" +AFLAGS_NOWARN :=$(call as-option,-Wa$(comma)-mno-warn-deprecated,-Wa$(comma)-W) + ifeq ($(CONFIG_THUMB2_KERNEL),y) AFLAGS_AUTOIT :=$(call as-option,-Wa$(comma)-mimplicit-it=always,-Wa$(comma)-mauto-it) -AFLAGS_NOWARN :=$(call as-option,-Wa$(comma)-mno-warn-deprecated,-Wa$(comma)-W) CFLAGS_ISA :=-mthumb $(AFLAGS_AUTOIT) $(AFLAGS_NOWARN) AFLAGS_ISA :=$(CFLAGS_ISA) -Wa$(comma)-mthumb # Work around buggy relocation from gas if requested: @@ -123,7 +125,7 @@ ifeq ($(CONFIG_THUMB2_AVOID_R_ARM_THM_JU CFLAGS_MODULE +=-fno-optimize-sibling-calls endif else -CFLAGS_ISA :=$(call cc-option,-marm,) +CFLAGS_ISA :=$(call cc-option,-marm,) $(AFLAGS_NOWARN) AFLAGS_ISA :=$(CFLAGS_ISA) endif
--- a/arch/arm/include/asm/unified.h +++ b/arch/arm/include/asm/unified.h @@ -20,8 +20,10 @@ #ifndef __ASM_UNIFIED_H #define __ASM_UNIFIED_H
-#if defined(__ASSEMBLY__) && defined(CONFIG_ARM_ASM_UNIFIED) +#if defined(__ASSEMBLY__) .syntax unified +#else +__asm__(".syntax unified"); #endif
#ifdef CONFIG_CPU_V7M @@ -64,77 +66,4 @@
#endif /* CONFIG_THUMB2_KERNEL */
-#ifndef CONFIG_ARM_ASM_UNIFIED - -/* - * If the unified assembly syntax isn't used (in ARM mode), these - * macros expand to an empty string - */ -#ifdef __ASSEMBLY__ - .macro it, cond - .endm - .macro itt, cond - .endm - .macro ite, cond - .endm - .macro ittt, cond - .endm - .macro itte, cond - .endm - .macro itet, cond - .endm - .macro itee, cond - .endm - .macro itttt, cond - .endm - .macro ittte, cond - .endm - .macro ittet, cond - .endm - .macro ittee, cond - .endm - .macro itett, cond - .endm - .macro itete, cond - .endm - .macro iteet, cond - .endm - .macro iteee, cond - .endm -#else /* !__ASSEMBLY__ */ -__asm__( -" .macro it, cond\n" -" .endm\n" -" .macro itt, cond\n" -" .endm\n" -" .macro ite, cond\n" -" .endm\n" -" .macro ittt, cond\n" -" .endm\n" -" .macro itte, cond\n" -" .endm\n" -" .macro itet, cond\n" -" .endm\n" -" .macro itee, cond\n" -" .endm\n" -" .macro itttt, cond\n" -" .endm\n" -" .macro ittte, cond\n" -" .endm\n" -" .macro ittet, cond\n" -" .endm\n" -" .macro ittee, cond\n" -" .endm\n" -" .macro itett, cond\n" -" .endm\n" -" .macro itete, cond\n" -" .endm\n" -" .macro iteet, cond\n" -" .endm\n" -" .macro iteee, cond\n" -" .endm\n"); -#endif /* __ASSEMBLY__ */ - -#endif /* CONFIG_ARM_ASM_UNIFIED */ - #endif /* !__ASM_UNIFIED_H */