2 files changed, 86 insertions, 0 deletions
diff --git a/host/include/aarch64/host/atomic128-cas.h b/host/include/aarch64/host/atomic128-cas.h
new file mode 100644
index 0000000000..80de58e06d
--- /dev/null
+++ b/host/include/aarch64/host/atomic128-cas.h
@@ -0,0 +1,43 @@
+/*
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ * Compare-and-swap for 128-bit atomic operations, AArch64 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 AARCH64_ATOMIC128_CAS_H
+#define AARCH64_ATOMIC128_CAS_H
+
+/* Through gcc 10, aarch64 has no support for 128-bit atomics.  */
+#if defined(CONFIG_ATOMIC128) || defined(CONFIG_CMPXCHG128)
+#include "host/include/generic/host/atomic128-cas.h"
+#else
+static inline Int128 atomic16_cmpxchg(Int128 *ptr, Int128 cmp, Int128 new)
+{
+    uint64_t cmpl = int128_getlo(cmp), cmph = int128_gethi(cmp);
+    uint64_t newl = int128_getlo(new), newh = int128_gethi(new);
+    uint64_t oldl, oldh;
+    uint32_t tmp;
+
+    asm("0: ldaxp %[oldl], %[oldh], %[mem]\n\t"
+        "cmp %[oldl], %[cmpl]\n\t"
+        "ccmp %[oldh], %[cmph], #0, eq\n\t"
+        "b.ne 1f\n\t"
+        "stlxp %w[tmp], %[newl], %[newh], %[mem]\n\t"
+        "cbnz %w[tmp], 0b\n"
+        "1:"
+        : [mem] "+m"(*ptr), [tmp] "=&r"(tmp),
+          [oldl] "=&r"(oldl), [oldh] "=&r"(oldh)
+        : [cmpl] "r"(cmpl), [cmph] "r"(cmph),
+          [newl] "r"(newl), [newh] "r"(newh)
+        : "memory", "cc");
+
+    return int128_make128(oldl, oldh);
+}
+# define HAVE_CMPXCHG128 1
+#endif
+
+#endif /* AARCH64_ATOMIC128_CAS_H */
diff --git a/host/include/generic/host/atomic128-cas.h b/host/include/generic/host/atomic128-cas.h
new file mode 100644
index 0000000000..513622fe34
--- /dev/null
+++ b/host/include/generic/host/atomic128-cas.h
@@ -0,0 +1,43 @@
+/*
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ * Compare-and-swap 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_CAS_H
+#define HOST_ATOMIC128_CAS_H
+
+#if defined(CONFIG_ATOMIC128)
+static inline Int128 atomic16_cmpxchg(Int128 *ptr, Int128 cmp, Int128 new)
+{
+    Int128Alias r, c, n;
+
+    c.s = cmp;
+    n.s = new;
+    r.i = qatomic_cmpxchg__nocheck((__int128_t *)ptr, c.i, n.i);
+    return r.s;
+}
+# define HAVE_CMPXCHG128 1
+#elif defined(CONFIG_CMPXCHG128)
+static inline Int128 atomic16_cmpxchg(Int128 *ptr, Int128 cmp, Int128 new)
+{
+    Int128Alias r, c, n;
+
+    c.s = cmp;
+    n.s = new;
+    r.i = __sync_val_compare_and_swap_16((__int128_t *)ptr, c.i, n.i);
+    return r.s;
+}
+# define HAVE_CMPXCHG128 1
+#else
+/* Fallback definition that must be optimized away, or error.  */
+Int128 QEMU_ERROR("unsupported atomic")
+    atomic16_cmpxchg(Int128 *ptr, Int128 cmp, Int128 new);
+# define HAVE_CMPXCHG128 0
+#endif
+
+#endif /* HOST_ATOMIC128_CAS_H */