From 480dfba2c9fe4e67f0d1f01a20c9a0fd09587ece Mon Sep 17 00:00:00 2001 From: Richard Henderson Date: Fri, 19 May 2023 21:12:34 -0700 Subject: qemu/atomic128: Add x86_64 atomic128-ldst.h MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit With CPUINFO_ATOMIC_VMOVDQA, we can perform proper atomic load/store without cmpxchg16b. Reviewed-by: Alex Bennée Signed-off-by: Richard Henderson --- host/include/x86_64/host/atomic128-ldst.h | 68 +++++++++++++++++++++++++++++++ 1 file changed, 68 insertions(+) create mode 100644 host/include/x86_64/host/atomic128-ldst.h diff --git a/host/include/x86_64/host/atomic128-ldst.h b/host/include/x86_64/host/atomic128-ldst.h new file mode 100644 index 0000000000..adc9332f91 --- /dev/null +++ b/host/include/x86_64/host/atomic128-ldst.h @@ -0,0 +1,68 @@ +/* + * SPDX-License-Identifier: GPL-2.0-or-later + * Load/store for 128-bit atomic operations, x86_64 version. + * + * Copyright (C) 2023 Linaro, Ltd. + * + * See docs/devel/atomics.rst for discussion about the guarantees each + * atomic primitive is meant to provide. + */ + +#ifndef AARCH64_ATOMIC128_LDST_H +#define AARCH64_ATOMIC128_LDST_H + +#ifdef CONFIG_INT128_TYPE +#include "host/cpuinfo.h" +#include "tcg/debug-assert.h" + +/* + * Through clang 16, with -mcx16, __atomic_load_n is incorrectly + * expanded to a read-write operation: lock cmpxchg16b. + */ + +#define HAVE_ATOMIC128_RO likely(cpuinfo & CPUINFO_ATOMIC_VMOVDQA) +#define HAVE_ATOMIC128_RW 1 + +static inline Int128 atomic16_read_ro(const Int128 *ptr) +{ + Int128Alias r; + + tcg_debug_assert(HAVE_ATOMIC128_RO); + asm("vmovdqa %1, %0" : "=x" (r.i) : "m" (*ptr)); + + return r.s; +} + +static inline Int128 atomic16_read_rw(Int128 *ptr) +{ + __int128_t *ptr_align = __builtin_assume_aligned(ptr, 16); + Int128Alias r; + + if (HAVE_ATOMIC128_RO) { + asm("vmovdqa %1, %0" : "=x" (r.i) : "m" (*ptr_align)); + } else { + r.i = __sync_val_compare_and_swap_16(ptr_align, 0, 0); + } + return r.s; +} + +static inline void atomic16_set(Int128 *ptr, Int128 val) +{ + __int128_t *ptr_align = __builtin_assume_aligned(ptr, 16); + Int128Alias new = { .s = val }; + + if (HAVE_ATOMIC128_RO) { + asm("vmovdqa %1, %0" : "=m"(*ptr_align) : "x" (new.i)); + } else { + __int128_t old; + do { + old = *ptr_align; + } while (!__sync_bool_compare_and_swap_16(ptr_align, old, new.i)); + } +} +#else +/* Provide QEMU_ERROR stubs. */ +#include "host/include/generic/host/atomic128-ldst.h" +#endif + +#endif /* AARCH64_ATOMIC128_LDST_H */ -- cgit v1.2.3