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Peter Anvin" Subject: [PATCH RESEND -tip 1/2] locking/atomic/x86: Introduce read64_nonatomic macro to x86_32 with cx8 Date: Wed, 5 Jun 2024 20:13:15 +0200 Message-ID: <20240605181424.3228-1-ubizjak@gmail.com> X-Mailer: git-send-email 2.42.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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 read64_nonatomic macro to load the value from atomic_t location in a faster non-atomic way and use it in atomic64_cx8_32.S. Signed-off-by: Uros Bizjak Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Borislav Petkov Cc: Dave Hansen Cc: "H. Peter Anvin" --- 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 -- 2.42.0