[PATCH v2 12/27] locking/atomic: x86: add preprocessor symbols

Mark Rutland
2023-06-05T07:02:53Z

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