From 91802a8ef410810db58907d2ea4c4adc00ef4688 Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Fri, 10 Aug 2012 11:12:20 +0000 Subject: ARM: pass -marm to gcc by default for both C and assembler The Linaro cross toolchain and probably others nowadays default to building in THUMB2 mode. When building a kernel for a CPU that does not support THUMB2, the compiler complains about incorrect flags. We can work around this by setting -marm for all non-T2 builds. -marm was passed unconditionally for C files previously, but nothing was passed to the gcc frontend when processing .S files, resulting in a warning. The assembler never defaults to ARM unless -Wa,-mthumb is supplied explicitly, so the files were still assembled correctly. This patch makes sure that -marm is passed for .S files too, and also avoids the redundant gcc -marm -mthumb in Thumb kernels. Without this patch, building assabet_defconfig results in: usr/initramfs_data.S:1:0: warning: target CPU does not support THUMB instructions [enabled by default] arch/arm/nwfpe/entry.S:1:0: warning: target CPU does not support THUMB instructions [enabled by default] firmware/cis/PCMLM28.cis.gen.S:1:0: warning: target CPU does not support THUMB instructions [enabled by default] (and many more) Signed-off-by: Arnd Bergmann Acked-by: Nicolas Pitre Acked-by: Dave Martin Cc: Russell King --- arch/arm/Makefile | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) (limited to 'arch/arm/Makefile') diff --git a/arch/arm/Makefile b/arch/arm/Makefile index f023e3acdfbd..5f914fca911b 100644 --- a/arch/arm/Makefile +++ b/arch/arm/Makefile @@ -21,8 +21,6 @@ endif OBJCOPYFLAGS :=-O binary -R .comment -S GZFLAGS :=-9 #KBUILD_CFLAGS +=-pipe -# Explicitly specifiy 32-bit ARM ISA since toolchain default can be -mthumb: -KBUILD_CFLAGS +=$(call cc-option,-marm,) # Never generate .eh_frame KBUILD_CFLAGS += $(call cc-option,-fno-dwarf2-cfi-asm) @@ -105,17 +103,20 @@ endif ifeq ($(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_THUMB2 :=-mthumb $(AFLAGS_AUTOIT) $(AFLAGS_NOWARN) -AFLAGS_THUMB2 :=$(CFLAGS_THUMB2) -Wa$(comma)-mthumb +CFLAGS_ISA :=-mthumb $(AFLAGS_AUTOIT) $(AFLAGS_NOWARN) +AFLAGS_ISA :=$(CFLAGS_ISA) -Wa$(comma)-mthumb # Work around buggy relocation from gas if requested: ifeq ($(CONFIG_THUMB2_AVOID_R_ARM_THM_JUMP11),y) CFLAGS_MODULE +=-fno-optimize-sibling-calls endif +else +CFLAGS_ISA :=$(call cc-option,-marm,) +AFLAGS_ISA :=$(CFLAGS_ISA) endif # Need -Uarm for gcc < 3.x -KBUILD_CFLAGS +=$(CFLAGS_ABI) $(CFLAGS_THUMB2) $(arch-y) $(tune-y) $(call cc-option,-mshort-load-bytes,$(call cc-option,-malignment-traps,)) -msoft-float -Uarm -KBUILD_AFLAGS +=$(CFLAGS_ABI) $(AFLAGS_THUMB2) $(arch-y) $(tune-y) -include asm/unified.h -msoft-float +KBUILD_CFLAGS +=$(CFLAGS_ABI) $(CFLAGS_ISA) $(arch-y) $(tune-y) $(call cc-option,-mshort-load-bytes,$(call cc-option,-malignment-traps,)) -msoft-float -Uarm +KBUILD_AFLAGS +=$(CFLAGS_ABI) $(AFLAGS_ISA) $(arch-y) $(tune-y) -include asm/unified.h -msoft-float CHECKFLAGS += -D__arm__ -- cgit 1.4.1 From e91b36efe51b5cbbfe5eb61a653cde5985ae8285 Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Tue, 4 Dec 2012 12:56:44 +0100 Subject: ARM: 7592/1: nommu: prevent generation of kernel unaligned memory accesses Recent ARMv7 toolchains assume that unaligned memory accesses will not fault and will instead be handled by the processor. For the nommu case (without an MPU), memory will be treated as strongly-ordered and therefore unaligned accesses may fault regardless of the SCTLR.A setting. This patch passes -mno-unaligned-access to GCC when compiling for nommu targets, preventing the generation of unaligned memory access in the kernel. Acked-by: Nicolas Pitre Tested-by: Jonathan Austin Signed-off-by: Will Deacon Signed-off-by: Russell King --- arch/arm/Makefile | 1 + 1 file changed, 1 insertion(+) (limited to 'arch/arm/Makefile') diff --git a/arch/arm/Makefile b/arch/arm/Makefile index f023e3acdfbd..cbe364210c7d 100644 --- a/arch/arm/Makefile +++ b/arch/arm/Makefile @@ -34,6 +34,7 @@ KBUILD_DEFCONFIG := versatile_defconfig # defines filename extension depending memory management type. ifeq ($(CONFIG_MMU),) MMUEXT := -nommu +KBUILD_CFLAGS += $(call cc-option,-mno-unaligned-access) endif ifeq ($(CONFIG_FRAME_POINTER),y) -- cgit 1.4.1