From 1551df35f296f0a8df32f4f2054254f46e8be252 Mon Sep 17 00:00:00 2001 From: Tom Rini Date: Tue, 25 Feb 2014 10:27:01 -0500 Subject: arm: Switch to -mno-unaligned-access when supported by the compiler When we tell the compiler to optimize for ARMv7 (and ARMv6 for that matter) it assumes a default of SCTRL.A being cleared and unaligned accesses being allowed and fast at the hardware level. We set this bit and must pass along -mno-unaligned-access so that the compiler will still breakdown accesses and not trigger a data abort. To better help understand the requirements of the project with respect to unaligned memory access, the Documentation/unaligned-memory-access.txt file has been added as doc/README.unaligned-memory-access.txt and is taken from the v3.14-rc1 tag of the kernel. Cc: Albert ARIBAUD Cc: Mans Rullgard Signed-off-by: Tom Rini --- arch/arm/cpu/armv7/config.mk | 7 +++++-- arch/arm/cpu/armv8/config.mk | 5 +---- arch/arm/lib/interrupts.c | 2 +- 3 files changed, 7 insertions(+), 7 deletions(-) (limited to 'arch') diff --git a/arch/arm/cpu/armv7/config.mk b/arch/arm/cpu/armv7/config.mk index d01f3d9f50..c048531bfc 100644 --- a/arch/arm/cpu/armv7/config.mk +++ b/arch/arm/cpu/armv7/config.mk @@ -10,9 +10,12 @@ PF_CPPFLAGS_ARMV7 := $(call cc-option, -march=armv7-a, -march=armv5) PLATFORM_CPPFLAGS += $(PF_CPPFLAGS_ARMV7) -# SEE README.arm-unaligned-accesses +# On supported platforms we set the bit which causes us to trap on unaligned +# memory access. This is the opposite of what the compiler expects to be +# the default so we must pass in -mno-unaligned-access so that it is aware +# of our decision. PF_NO_UNALIGNED := $(call cc-option, -mno-unaligned-access,) -PLATFORM_NO_UNALIGNED := $(PF_NO_UNALIGNED) +PLATFORM_CPPFLAGS += $(PF_NO_UNALIGNED) ifneq ($(CONFIG_IMX_CONFIG),) ifdef CONFIG_SPL diff --git a/arch/arm/cpu/armv8/config.mk b/arch/arm/cpu/armv8/config.mk index 027a68ca57..f5b95591af 100644 --- a/arch/arm/cpu/armv8/config.mk +++ b/arch/arm/cpu/armv8/config.mk @@ -6,10 +6,7 @@ # PLATFORM_RELFLAGS += -fno-common -ffixed-x18 -# SEE README.arm-unaligned-accesses -PF_NO_UNALIGNED := $(call cc-option, -mstrict-align) -PLATFORM_NO_UNALIGNED := $(PF_NO_UNALIGNED) - PF_CPPFLAGS_ARMV8 := $(call cc-option, -march=armv8-a) +PF_NO_UNALIGNED := $(call cc-option, -mstrict-align) PLATFORM_CPPFLAGS += $(PF_CPPFLAGS_ARMV8) PLATFORM_CPPFLAGS += $(PF_NO_UNALIGNED) diff --git a/arch/arm/lib/interrupts.c b/arch/arm/lib/interrupts.c index 603bf14627..758b01371e 100644 --- a/arch/arm/lib/interrupts.c +++ b/arch/arm/lib/interrupts.c @@ -153,7 +153,7 @@ void do_prefetch_abort (struct pt_regs *pt_regs) void do_data_abort (struct pt_regs *pt_regs) { - printf ("data abort\n\n MAYBE you should read doc/README.arm-unaligned-accesses\n\n"); + printf ("data abort\n"); show_regs (pt_regs); bad_mode (); } -- cgit v1.2.1