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authorWill Deacon <will.deacon@arm.com>2015-02-03 16:14:13 +0000
committerWill Deacon <will.deacon@arm.com>2015-07-27 15:28:50 +0100
commitc09d6a04d17d730b0463207a26ece082772b59ee (patch)
tree43aec4a96946d28bc0fd985b1219317bdcb2b8d2 /arch/arm64/Makefile
parentc0385b24af15020a1e505f2c984db0d7c0d017e1 (diff)
downloadlinux-c09d6a04d17d730b0463207a26ece082772b59ee.tar.gz
arm64: atomics: patch in lse instructions when supported by the CPU
On CPUs which support the LSE atomic instructions introduced in ARMv8.1, it makes sense to use them in preference to ll/sc sequences. This patch introduces runtime patching of atomic_t and atomic64_t routines so that the call-site for the out-of-line ll/sc sequences is patched with an LSE atomic instruction when we detect that the CPU supports it. If binutils is not recent enough to assemble the LSE instructions, then the ll/sc sequences are inlined as though CONFIG_ARM64_LSE_ATOMICS=n. Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'arch/arm64/Makefile')
-rw-r--r--arch/arm64/Makefile13
1 files changed, 12 insertions, 1 deletions
diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
index 0953a97b5119..15ff5b4156fd 100644
--- a/arch/arm64/Makefile
+++ b/arch/arm64/Makefile
@@ -17,7 +17,18 @@ GZFLAGS :=-9
KBUILD_DEFCONFIG := defconfig
-KBUILD_CFLAGS += -mgeneral-regs-only
+# Check for binutils support for specific extensions
+lseinstr := $(call as-instr,.arch_extension lse,-DCONFIG_AS_LSE=1)
+
+ifeq ($(CONFIG_ARM64_LSE_ATOMICS), y)
+ ifeq ($(lseinstr),)
+$(warning LSE atomics not supported by binutils)
+ endif
+endif
+
+KBUILD_CFLAGS += -mgeneral-regs-only $(lseinstr)
+KBUILD_AFLAGS += $(lseinstr)
+
ifeq ($(CONFIG_CPU_BIG_ENDIAN), y)
KBUILD_CPPFLAGS += -mbig-endian
AS += -EB