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authorRussell King <rmk+kernel@arm.linux.org.uk>2014-07-04 17:44:36 +0400
committerRussell King <rmk+kernel@arm.linux.org.uk>2014-07-18 15:29:47 +0400
commita11dd731f5ead63ab3d757bbb1ab631063f6c034 (patch)
treeaa658fc0c27f728fcc2057dc0eb1c962d2601c9e /arch/arm/mm/Kconfig
parentaf040ffc9ba1e079ee4c0748aff64fa3d4716fa5 (diff)
downloadlinux-a11dd731f5ead63ab3d757bbb1ab631063f6c034.tar.xz
ARM: SWP emulation: always enable when SMP is enabled
SWP is deprecated in ARMv6 and ARMv7 CPUs, but more importantly, when running on a SMP system, SWP doesn't guarantee atomicity. This means it can't really be used (by userspace) for locking purposes in a SMP environment. Currently, many configurations leave the SWP emulation disabled, which means we never know if userspace executes this instruction on ARMv7 hardware. Rectify this by enabling SWP emulation for ARMv7 with SMP (where we can trap the instruction.) Tested-by: Tony Lindgren <tony@atomide.com> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/mm/Kconfig')
-rw-r--r--arch/arm/mm/Kconfig2
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig
index c348eaee7ee2..c78c7db6aa83 100644
--- a/arch/arm/mm/Kconfig
+++ b/arch/arm/mm/Kconfig
@@ -669,7 +669,7 @@ config ARM_VIRT_EXT
details.
config SWP_EMULATE
- bool "Emulate SWP/SWPB instructions"
+ bool "Emulate SWP/SWPB instructions" if !SMP
depends on CPU_V7
default y if SMP
select HAVE_PROC_CPU if PROC_FS