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From:   Mark Rutland <mark.rutland@arm.com>
To:     linux-kernel@vger.kernel.org
Cc:     akiyks@gmail.com, boqun.feng@gmail.com, corbet@lwn.net,
        keescook@chromium.org, linux@armlinux.org.uk,
        linux-doc@vger.kernel.org, mark.rutland@arm.com,
        mchehab@kernel.org, paulmck@kernel.org, peterz@infradead.org,
        rdunlap@infradead.org, sstabellini@kernel.org, will@kernel.org
Subject: [PATCH v2 12/27] locking/atomic: x86: add preprocessor symbols
Date:   Mon,  5 Jun 2023 08:01:09 +0100
Message-Id: <20230605070124.3741859-13-mark.rutland@arm.com>
In-Reply-To: <20230605070124.3741859-1-mark.rutland@arm.com>
References: <20230605070124.3741859-1-mark.rutland@arm.com>
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Some atomics can be implemented in several different ways, e.g.
FULL/ACQUIRE/RELEASE ordered atomics can be implemented in terms of
RELAXED atomics, and ACQUIRE/RELEASE/RELAXED can be implemented in terms
of FULL ordered atomics. Other atomics are optional, and don't exist in
some configurations (e.g. not all architectures implement the 128-bit
cmpxchg ops).

Subsequent patches will require that architectures define a preprocessor
symbol for any atomic (or ordering variant) which is optional. This will
make the fallback ifdeffery more robust, and simplify future changes.

Add the required definitions to arch/x86.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
---
 arch/x86/include/asm/cmpxchg_64.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/x86/include/asm/cmpxchg_64.h b/arch/x86/include/asm/cmpxchg_64.h
index 3e6e3eef701b3..44b08b53ab32f 100644
--- a/arch/x86/include/asm/cmpxchg_64.h
+++ b/arch/x86/include/asm/cmpxchg_64.h
@@ -45,11 +45,13 @@ static __always_inline u128 arch_cmpxchg128(volatile u128 *ptr, u128 old, u128 n
 {
 	return __arch_cmpxchg128(ptr, old, new, LOCK_PREFIX);
 }
+#define arch_cmpxchg128 arch_cmpxchg128
 
 static __always_inline u128 arch_cmpxchg128_local(volatile u128 *ptr, u128 old, u128 new)
 {
 	return __arch_cmpxchg128(ptr, old, new,);
 }
+#define arch_cmpxchg128_local arch_cmpxchg128_local
 
 #define __arch_try_cmpxchg128(_ptr, _oldp, _new, _lock)			\
 ({									\
@@ -75,11 +77,13 @@ static __always_inline bool arch_try_cmpxchg128(volatile u128 *ptr, u128 *oldp,
 {
 	return __arch_try_cmpxchg128(ptr, oldp, new, LOCK_PREFIX);
 }
+#define arch_try_cmpxchg128 arch_try_cmpxchg128
 
 static __always_inline bool arch_try_cmpxchg128_local(volatile u128 *ptr, u128 *oldp, u128 new)
 {
 	return __arch_try_cmpxchg128(ptr, oldp, new,);
 }
+#define arch_try_cmpxchg128_local arch_try_cmpxchg128_local
 
 #define system_has_cmpxchg128()		boot_cpu_has(X86_FEATURE_CX16)
 
-- 
2.30.2