[PATCH] arm64: remove HAVE_CMPXCHG_LOCAL

[Jisheng Zhang]

It turns out the generic disable/enable irq this_cpu_cmpxchg
implementation is faster than LL/SC or lse implementation. Remove
HAVE_CMPXCHG_LOCAL for better performance on arm64.

Tested on Quad 1.9GHZ CA55 platform:
average mod_node_page_state() cost decreases from 167ns to 103ns
the spawn (30 duration) benchmark in unixbench is improved
from 147494 lps to 150561 lps, improved by 2.1%

Tested on Quad 2.1GHZ CA73 platform:
average mod_node_page_state() cost decreases from 113ns to 85ns
the spawn (30 duration) benchmark in unixbench is improved
from 209844 lps to 212581 lps, improved by 1.3%

Signed-off-by: Jisheng Zhang <jszhang at kernel.org>
---
 arch/arm64/Kconfig              |  1 -
 arch/arm64/include/asm/percpu.h | 24 ------------------------
 2 files changed, 25 deletions(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 38dba5f7e4d2..5e7e2e65d5a5 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -205,7 +205,6 @@ config ARM64
 	select HAVE_EBPF_JIT
 	select HAVE_C_RECORDMCOUNT
 	select HAVE_CMPXCHG_DOUBLE
-	select HAVE_CMPXCHG_LOCAL
 	select HAVE_CONTEXT_TRACKING_USER
 	select HAVE_DEBUG_KMEMLEAK
 	select HAVE_DMA_CONTIGUOUS
diff --git a/arch/arm64/include/asm/percpu.h b/arch/arm64/include/asm/percpu.h
index b57b2bb00967..70ffe566cb4b 100644
--- a/arch/arm64/include/asm/percpu.h
+++ b/arch/arm64/include/asm/percpu.h
@@ -232,30 +232,6 @@ PERCPU_RET_OP(add, add, ldadd)
 #define this_cpu_xchg_8(pcp, val)	\
 	_pcp_protect_return(xchg_relaxed, pcp, val)
 
-#define this_cpu_cmpxchg_1(pcp, o, n)	\
-	_pcp_protect_return(cmpxchg_relaxed, pcp, o, n)
-#define this_cpu_cmpxchg_2(pcp, o, n)	\
-	_pcp_protect_return(cmpxchg_relaxed, pcp, o, n)
-#define this_cpu_cmpxchg_4(pcp, o, n)	\
-	_pcp_protect_return(cmpxchg_relaxed, pcp, o, n)
-#define this_cpu_cmpxchg_8(pcp, o, n)	\
-	_pcp_protect_return(cmpxchg_relaxed, pcp, o, n)
-
-#define this_cpu_cmpxchg64(pcp, o, n)	this_cpu_cmpxchg_8(pcp, o, n)
-
-#define this_cpu_cmpxchg128(pcp, o, n)					\
-({									\
-	typedef typeof(pcp) pcp_op_T__;					\
-	u128 old__, new__, ret__;					\
-	pcp_op_T__ *ptr__;						\
-	old__ = o;							\
-	new__ = n;							\
-	preempt_disable_notrace();					\
-	ptr__ = raw_cpu_ptr(&(pcp));					\
-	ret__ = cmpxchg128_local((void *)ptr__, old__, new__);		\
-	preempt_enable_notrace();					\
-	ret__;								\
-})
 
 #ifdef __KVM_NVHE_HYPERVISOR__
 extern unsigned long __hyp_per_cpu_offset(unsigned int cpu);
-- 
2.51.0