diff options
| author | Will Deacon <will.deacon@arm.com> | 2015-02-03 12:39:03 +0000 |
|---|---|---|
| committer | Will Deacon <will.deacon@arm.com> | 2015-07-27 15:28:50 +0100 |
| commit | c0385b24af15020a1e505f2c984db0d7c0d017e1 (patch) | |
| tree | 50cf977ef4ba5de29e1c9a931588bc340c9e103c /arch/arm64/Kconfig | |
| parent | d964b7229e7f94428a1e8d26999adffbe8a69db2 (diff) | |
arm64: introduce CONFIG_ARM64_LSE_ATOMICS as fallback to ll/sc atomics
In order to patch in the new atomic instructions at runtime, we need to
generate wrappers around the out-of-line exclusive load/store atomics.
This patch adds a new Kconfig option, CONFIG_ARM64_LSE_ATOMICS. which
causes our atomic functions to branch to the out-of-line ll/sc
implementations. To avoid the register spill overhead of the PCS, the
out-of-line functions are compiled with specific compiler flags to
force out-of-line save/restore of any registers that are usually
caller-saved.
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'arch/arm64/Kconfig')
| -rw-r--r-- | arch/arm64/Kconfig | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 5372e1e0c11c..8dabffa82ef8 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -618,6 +618,18 @@ config ARM64_PAN The feature is detected at runtime, and will remain as a 'nop' instruction if the cpu does not implement the feature. +config ARM64_LSE_ATOMICS + bool "ARMv8.1 atomic instructions" + help + As part of the Large System Extensions, ARMv8.1 introduces new + atomic instructions that are designed specifically to scale in + very large systems. + + Say Y here to make use of these instructions for the in-kernel + atomic routines. This incurs a small overhead on CPUs that do + not support these instructions and requires the kernel to be + built with binutils >= 2.25. + menuconfig ARMV8_DEPRECATED bool "Emulate deprecated/obsolete ARMv8 instructions" depends on COMPAT |