tree 50cf977ef4ba5de29e1c9a931588bc340c9e103c
parent d964b7229e7f94428a1e8d26999adffbe8a69db2
author Will Deacon <will.deacon@arm.com> 1422967143 +0000
committer Will Deacon <will.deacon@arm.com> 1438007330 +0100

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>