[PATCH 1/9] arm: select different compiler flags for ARM CortexM3

Paul Osmialowski
2015-06-23T21:50:49Z

This one is inspired by two commits published on Emcraft git repo:

https://github.com/EmcraftSystems/linux-emcraft.git

1) 6302b692f570ff9d5645a6e72c11f87b0c1aa409
RT #62654. Fixed kernel crashes while running httpd by enabling
"-mfix-cortex-m3-ldrd" compiler option, which prevents compiler from
generating code like 'ldrd Ra, Rb, [Ra, #Imm]' - according to the 602117
Cortex-M3 Errata it may result in incorrect base register when interrupted
or faulted.

by: Yuri Tikhonov <yur@emcraft.com>

2) 359d3cda84c01c0f3fae1a519b97a31f318f57ab
RT #62654. Removed "--march=..." leaving only "-mcpu=cortex-m3" to make
sure only the correct instructions will be generated.

by: Sergei Poselenov <sposelenov@emcraft.com>

I reworked these patches to make them less intrusive.

Signed-off-by: Paul Osmialowski <pawelo@king.net.pl>
---
arch/arm/Kconfig | 2 +-
arch/arm/Makefile | 1 +
arch/arm/mm/Kconfig | 11 ++++++++++-
3 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index a750c14..8e3a833 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -32,7 +32,7 @@ config ARM
select HANDLE_DOMAIN_IRQ
select HARDIRQS_SW_RESEND
select HAVE_ARCH_AUDITSYSCALL if (AEABI && !OABI_COMPAT)
- select HAVE_ARCH_BITREVERSE if (CPU_32v7M || CPU_32v7) && !CPU_32v6
+ select HAVE_ARCH_BITREVERSE if (CPU_32v7M || CPU_32v7M3 || CPU_32v7) && !CPU_32v6
select HAVE_ARCH_JUMP_LABEL if !XIP_KERNEL && !CPU_ENDIAN_BE32
select HAVE_ARCH_KGDB if !CPU_ENDIAN_BE32
select HAVE_ARCH_SECCOMP_FILTER if (AEABI && !OABI_COMPAT)
diff --git a/arch/arm/Makefile b/arch/arm/Makefile
index 07ab3d2..a7e1007 100644
--- a/arch/arm/Makefile
+++ b/arch/arm/Makefile
@@ -58,6 +58,7 @@ endif
# Note that GCC does not numerically define an architecture version
# macro, but instead defines a whole series of macros which makes
# testing for a specific architecture or later rather impossible.
+arch-$(CONFIG_CPU_32v7M3) =-D__LINUX_ARM_ARCH__=7 -mcpu=cortex-m3 -Wa,-mcpu=cortex-m3
arch-$(CONFIG_CPU_32v7M) =-D__LINUX_ARM_ARCH__=7 -march=armv7-m -Wa,-march=armv7-m
arch-$(CONFIG_CPU_32v7) =-D__LINUX_ARM_ARCH__=7 $(call cc-option,-march=armv7-a,-march=armv5t -Wa$(comma)-march=armv7-a)
arch-$(CONFIG_CPU_32v6) =-D__LINUX_ARM_ARCH__=6 $(call cc-option,-march=armv6,-march=armv5t -Wa$(comma)-march=armv6)
diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig
index 7c6b976..d19cb4d 100644
--- a/arch/arm/mm/Kconfig
+++ b/arch/arm/mm/Kconfig
@@ -401,12 +401,18 @@ config CPU_V7
# ARMv7M
config CPU_V7M
bool
- select CPU_32v7M
+ select CPU_32v7M if !CPU_CORTEXM3
+ select CPU_32v7M3 if CPU_CORTEXM3
select CPU_ABRT_NOMMU
select CPU_CACHE_NOP
select CPU_PABRT_LEGACY
select CPU_THUMBONLY

+# ARM CortexM3
+config CPU_CORTEXM3
+ bool
+ select CPU_V7M
+
config CPU_THUMBONLY
bool
# There are no CPUs available with MMU that don't implement an ARM ISA:
@@ -457,6 +463,9 @@ config CPU_32v7
config CPU_32v7M
bool

+config CPU_32v7M3
+ bool
+
# The abort model
config CPU_ABRT_NOMMU
bool
--
2.3.6