include/host: Split out atomic128-ldst.h

Separates the aarch64-specific portion into its own file.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

1 files changed, 57 insertions, 0 deletions

diff --git a/host/include/generic/host/atomic128-ldst.h b/host/include/generic/host/atomic128-ldst.h
new file mode 100644
index 0000000000..e7354a9255
--- /dev/null
+++ b/host/include/generic/host/atomic128-ldst.h
@@ -0,0 +1,57 @@
+/*
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ * Load/store for 128-bit atomic operations, generic version.
+ *
+ * Copyright (C) 2018, 2023 Linaro, Ltd.
+ *
+ * See docs/devel/atomics.rst for discussion about the guarantees each
+ * atomic primitive is meant to provide.
+ */
+
+#ifndef HOST_ATOMIC128_LDST_H
+#define HOST_ATOMIC128_LDST_H
+
+#if defined(CONFIG_ATOMIC128)
+static inline Int128 atomic16_read(Int128 *ptr)
+{
+    Int128Alias r;
+
+    r.i = qatomic_read__nocheck((__int128_t *)ptr);
+    return r.s;
+}
+
+static inline void atomic16_set(Int128 *ptr, Int128 val)
+{
+    Int128Alias v;
+
+    v.s = val;
+    qatomic_set__nocheck((__int128_t *)ptr, v.i);
+}
+
+# define HAVE_ATOMIC128 1
+#elif !defined(CONFIG_USER_ONLY) && HAVE_CMPXCHG128
+static inline Int128 atomic16_read(Int128 *ptr)
+{
+    /* Maybe replace 0 with 0, returning the old value.  */
+    Int128 z = int128_make64(0);
+    return atomic16_cmpxchg(ptr, z, z);
+}
+
+static inline void atomic16_set(Int128 *ptr, Int128 val)
+{
+    Int128 old = *ptr, cmp;
+    do {
+        cmp = old;
+        old = atomic16_cmpxchg(ptr, cmp, val);
+    } while (int128_ne(old, cmp));
+}
+
+# define HAVE_ATOMIC128 1
+#else
+/* Fallback definitions that must be optimized away, or error.  */
+Int128 QEMU_ERROR("unsupported atomic") atomic16_read(Int128 *ptr);
+void QEMU_ERROR("unsupported atomic") atomic16_set(Int128 *ptr, Int128 val);
+# define HAVE_ATOMIC128 0
+#endif
+
+#endif /* HOST_ATOMIC128_LDST_H */