From 6e30a7c98a9fda2f894e970e9cd637657f39c59d Mon Sep 17 00:00:00 2001 From: Uros Bizjak Date: Wed, 5 Jun 2024 20:13:15 +0200 Subject: [PATCH] locking/atomic/x86: Introduce the read64_nonatomic macro to x86_32 with cx8 As described in commit: e73c4e34a0e9 ("locking/atomic/x86: Introduce arch_atomic64_read_nonatomic() to x86_32") the value preload before the CMPXCHG loop does not need to be atomic. Introduce the read64_nonatomic assembly macro to load the value from a atomic_t location in a faster non-atomic way and use it in atomic64_cx8_32.S. Signed-off-by: Uros Bizjak Signed-off-by: Ingo Molnar Cc: Linus Torvalds Link: https://lore.kernel.org/r/20240605181424.3228-1-ubizjak@gmail.com --- arch/x86/lib/atomic64_cx8_32.S | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/arch/x86/lib/atomic64_cx8_32.S b/arch/x86/lib/atomic64_cx8_32.S index 90afb488b396..b2eff07d65e4 100644 --- a/arch/x86/lib/atomic64_cx8_32.S +++ b/arch/x86/lib/atomic64_cx8_32.S @@ -16,6 +16,11 @@ cmpxchg8b (\reg) .endm +.macro read64_nonatomic reg + movl (\reg), %eax + movl 4(\reg), %edx +.endm + SYM_FUNC_START(atomic64_read_cx8) read64 %ecx RET @@ -51,7 +56,7 @@ SYM_FUNC_START(atomic64_\func\()_return_cx8) movl %edx, %edi movl %ecx, %ebp - read64 %ecx + read64_nonatomic %ecx 1: movl %eax, %ebx movl %edx, %ecx @@ -79,7 +84,7 @@ addsub_return sub sub sbb SYM_FUNC_START(atomic64_\func\()_return_cx8) pushl %ebx - read64 %esi + read64_nonatomic %esi 1: movl %eax, %ebx movl %edx, %ecx