arm64: introduce CONFIG_ARM64_LSE_ATOMICS as fallback to ll/sc atomics
authorWill Deacon <will.deacon@arm.com>
Tue, 3 Feb 2015 12:39:03 +0000 (12:39 +0000)
committerWill Deacon <will.deacon@arm.com>
Mon, 27 Jul 2015 14:28:50 +0000 (15:28 +0100)
commitc0385b24af15020a1e505f2c984db0d7c0d017e1
tree50cf977ef4ba5de29e1c9a931588bc340c9e103c
parentd964b7229e7f94428a1e8d26999adffbe8a69db2
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>
arch/arm64/Kconfig
arch/arm64/include/asm/atomic.h
arch/arm64/include/asm/atomic_ll_sc.h
arch/arm64/include/asm/atomic_lse.h [new file with mode: 0644]
arch/arm64/lib/Makefile
arch/arm64/lib/atomic_ll_sc.c [new file with mode: 0644]