locking/atomic: make atomic*_{cmp,}xchg optional

Most architectures define the atomic/atomic64 xchg and cmpxchg
operations in terms of arch_xchg and arch_cmpxchg respectfully.

Add fallbacks for these cases and remove the trivial cases from arch
code. On some architectures the existing definitions are kept as these
are used to build other arch_atomic*() operations.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20230605070124.3741859-5-mark.rutland@arm.com

1 files changed, 157 insertions, 1 deletions

diff --git a/include/linux/atomic/atomic-arch-fallback.h b/include/linux/atomic/atomic-arch-fallback.h
index 3ce4cb5e790c..1a2d81dbc2e4 100644
--- a/include/linux/atomic/atomic-arch-fallback.h
+++ b/include/linux/atomic/atomic-arch-fallback.h
@@ -1091,9 +1091,48 @@ arch_atomic_fetch_xor(int i, atomic_t *v)
 #endif /* arch_atomic_fetch_xor_relaxed */
 
 #ifndef arch_atomic_xchg_relaxed
+#ifdef arch_atomic_xchg
 #define arch_atomic_xchg_acquire arch_atomic_xchg
 #define arch_atomic_xchg_release arch_atomic_xchg
 #define arch_atomic_xchg_relaxed arch_atomic_xchg
+#endif /* arch_atomic_xchg */
+
+#ifndef arch_atomic_xchg
+static __always_inline int
+arch_atomic_xchg(atomic_t *v, int new)
+{
+	return arch_xchg(&v->counter, new);
+}
+#define arch_atomic_xchg arch_atomic_xchg
+#endif
+
+#ifndef arch_atomic_xchg_acquire
+static __always_inline int
+arch_atomic_xchg_acquire(atomic_t *v, int new)
+{
+	return arch_xchg_acquire(&v->counter, new);
+}
+#define arch_atomic_xchg_acquire arch_atomic_xchg_acquire
+#endif
+
+#ifndef arch_atomic_xchg_release
+static __always_inline int
+arch_atomic_xchg_release(atomic_t *v, int new)
+{
+	return arch_xchg_release(&v->counter, new);
+}
+#define arch_atomic_xchg_release arch_atomic_xchg_release
+#endif
+
+#ifndef arch_atomic_xchg_relaxed
+static __always_inline int
+arch_atomic_xchg_relaxed(atomic_t *v, int new)
+{
+	return arch_xchg_relaxed(&v->counter, new);
+}
+#define arch_atomic_xchg_relaxed arch_atomic_xchg_relaxed
+#endif
+
 #else /* arch_atomic_xchg_relaxed */
 
 #ifndef arch_atomic_xchg_acquire
@@ -1133,9 +1172,48 @@ arch_atomic_xchg(atomic_t *v, int i)
 #endif /* arch_atomic_xchg_relaxed */
 
 #ifndef arch_atomic_cmpxchg_relaxed
+#ifdef arch_atomic_cmpxchg
 #define arch_atomic_cmpxchg_acquire arch_atomic_cmpxchg
 #define arch_atomic_cmpxchg_release arch_atomic_cmpxchg
 #define arch_atomic_cmpxchg_relaxed arch_atomic_cmpxchg
+#endif /* arch_atomic_cmpxchg */
+
+#ifndef arch_atomic_cmpxchg
+static __always_inline int
+arch_atomic_cmpxchg(atomic_t *v, int old, int new)
+{
+	return arch_cmpxchg(&v->counter, old, new);
+}
+#define arch_atomic_cmpxchg arch_atomic_cmpxchg
+#endif
+
+#ifndef arch_atomic_cmpxchg_acquire
+static __always_inline int
+arch_atomic_cmpxchg_acquire(atomic_t *v, int old, int new)
+{
+	return arch_cmpxchg_acquire(&v->counter, old, new);
+}
+#define arch_atomic_cmpxchg_acquire arch_atomic_cmpxchg_acquire
+#endif
+
+#ifndef arch_atomic_cmpxchg_release
+static __always_inline int
+arch_atomic_cmpxchg_release(atomic_t *v, int old, int new)
+{
+	return arch_cmpxchg_release(&v->counter, old, new);
+}
+#define arch_atomic_cmpxchg_release arch_atomic_cmpxchg_release
+#endif
+
+#ifndef arch_atomic_cmpxchg_relaxed
+static __always_inline int
+arch_atomic_cmpxchg_relaxed(atomic_t *v, int old, int new)
+{
+	return arch_cmpxchg_relaxed(&v->counter, old, new);
+}
+#define arch_atomic_cmpxchg_relaxed arch_atomic_cmpxchg_relaxed
+#endif
+
 #else /* arch_atomic_cmpxchg_relaxed */
 
 #ifndef arch_atomic_cmpxchg_acquire
@@ -2225,9 +2303,48 @@ arch_atomic64_fetch_xor(s64 i, atomic64_t *v)
 #endif /* arch_atomic64_fetch_xor_relaxed */
 
 #ifndef arch_atomic64_xchg_relaxed
+#ifdef arch_atomic64_xchg
 #define arch_atomic64_xchg_acquire arch_atomic64_xchg
 #define arch_atomic64_xchg_release arch_atomic64_xchg
 #define arch_atomic64_xchg_relaxed arch_atomic64_xchg
+#endif /* arch_atomic64_xchg */
+
+#ifndef arch_atomic64_xchg
+static __always_inline s64
+arch_atomic64_xchg(atomic64_t *v, s64 new)
+{
+	return arch_xchg(&v->counter, new);
+}
+#define arch_atomic64_xchg arch_atomic64_xchg
+#endif
+
+#ifndef arch_atomic64_xchg_acquire
+static __always_inline s64
+arch_atomic64_xchg_acquire(atomic64_t *v, s64 new)
+{
+	return arch_xchg_acquire(&v->counter, new);
+}
+#define arch_atomic64_xchg_acquire arch_atomic64_xchg_acquire
+#endif
+
+#ifndef arch_atomic64_xchg_release
+static __always_inline s64
+arch_atomic64_xchg_release(atomic64_t *v, s64 new)
+{
+	return arch_xchg_release(&v->counter, new);
+}
+#define arch_atomic64_xchg_release arch_atomic64_xchg_release
+#endif
+
+#ifndef arch_atomic64_xchg_relaxed
+static __always_inline s64
+arch_atomic64_xchg_relaxed(atomic64_t *v, s64 new)
+{
+	return arch_xchg_relaxed(&v->counter, new);
+}
+#define arch_atomic64_xchg_relaxed arch_atomic64_xchg_relaxed
+#endif
+
 #else /* arch_atomic64_xchg_relaxed */
 
 #ifndef arch_atomic64_xchg_acquire
@@ -2267,9 +2384,48 @@ arch_atomic64_xchg(atomic64_t *v, s64 i)
 #endif /* arch_atomic64_xchg_relaxed */
 
 #ifndef arch_atomic64_cmpxchg_relaxed
+#ifdef arch_atomic64_cmpxchg
 #define arch_atomic64_cmpxchg_acquire arch_atomic64_cmpxchg
 #define arch_atomic64_cmpxchg_release arch_atomic64_cmpxchg
 #define arch_atomic64_cmpxchg_relaxed arch_atomic64_cmpxchg
+#endif /* arch_atomic64_cmpxchg */
+
+#ifndef arch_atomic64_cmpxchg
+static __always_inline s64
+arch_atomic64_cmpxchg(atomic64_t *v, s64 old, s64 new)
+{
+	return arch_cmpxchg(&v->counter, old, new);
+}
+#define arch_atomic64_cmpxchg arch_atomic64_cmpxchg
+#endif
+
+#ifndef arch_atomic64_cmpxchg_acquire
+static __always_inline s64
+arch_atomic64_cmpxchg_acquire(atomic64_t *v, s64 old, s64 new)
+{
+	return arch_cmpxchg_acquire(&v->counter, old, new);
+}
+#define arch_atomic64_cmpxchg_acquire arch_atomic64_cmpxchg_acquire
+#endif
+
+#ifndef arch_atomic64_cmpxchg_release
+static __always_inline s64
+arch_atomic64_cmpxchg_release(atomic64_t *v, s64 old, s64 new)
+{
+	return arch_cmpxchg_release(&v->counter, old, new);
+}
+#define arch_atomic64_cmpxchg_release arch_atomic64_cmpxchg_release
+#endif
+
+#ifndef arch_atomic64_cmpxchg_relaxed
+static __always_inline s64
+arch_atomic64_cmpxchg_relaxed(atomic64_t *v, s64 old, s64 new)
+{
+	return arch_cmpxchg_relaxed(&v->counter, old, new);
+}
+#define arch_atomic64_cmpxchg_relaxed arch_atomic64_cmpxchg_relaxed
+#endif
+
 #else /* arch_atomic64_cmpxchg_relaxed */
 
 #ifndef arch_atomic64_cmpxchg_acquire
@@ -2597,4 +2753,4 @@ arch_atomic64_dec_if_positive(atomic64_t *v)
 #endif
 
 #endif /* _LINUX_ATOMIC_FALLBACK_H */
-// 9f0fd6ed53267c6ec64e36cd18e6fd8df57ea277
+// e1cee558cc61cae887890db30fcdf93baca9f498