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author | Will Deacon <will.deacon@arm.com> | 2015-02-03 12:39:03 (GMT) |
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committer | Will Deacon <will.deacon@arm.com> | 2015-07-27 14:28:50 (GMT) |
commit | c0385b24af15020a1e505f2c984db0d7c0d017e1 (patch) | |
tree | 50cf977ef4ba5de29e1c9a931588bc340c9e103c /arch/arm64/lib/Makefile | |
parent | d964b7229e7f94428a1e8d26999adffbe8a69db2 (diff) | |
download | linux-c0385b24af15020a1e505f2c984db0d7c0d017e1.tar.xz |
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/lib/Makefile')
-rw-r--r-- | arch/arm64/lib/Makefile | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/arch/arm64/lib/Makefile b/arch/arm64/lib/Makefile index d98d3e3..1a811ec 100644 --- a/arch/arm64/lib/Makefile +++ b/arch/arm64/lib/Makefile @@ -3,3 +3,16 @@ lib-y := bitops.o clear_user.o delay.o copy_from_user.o \ clear_page.o memchr.o memcpy.o memmove.o memset.o \ memcmp.o strcmp.o strncmp.o strlen.o strnlen.o \ strchr.o strrchr.o + +# Tell the compiler to treat all general purpose registers as +# callee-saved, which allows for efficient runtime patching of the bl +# instruction in the caller with an atomic instruction when supported by +# the CPU. Result and argument registers are handled correctly, based on +# the function prototype. +lib-$(CONFIG_ARM64_LSE_ATOMICS) += atomic_ll_sc.o +CFLAGS_atomic_ll_sc.o := -fcall-used-x0 -ffixed-x1 -ffixed-x2 \ + -ffixed-x3 -ffixed-x4 -ffixed-x5 -ffixed-x6 \ + -ffixed-x7 -fcall-saved-x8 -fcall-saved-x9 \ + -fcall-saved-x10 -fcall-saved-x11 -fcall-saved-x12 \ + -fcall-saved-x13 -fcall-saved-x14 -fcall-saved-x15 \ + -fcall-saved-x16 -fcall-saved-x17 -fcall-saved-x18 |