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| -rw-r--r-- | host/include/x86_64/host/load-extract-al16-al8.h | 50 |
1 files changed, 50 insertions, 0 deletions
diff --git a/host/include/x86_64/host/load-extract-al16-al8.h b/host/include/x86_64/host/load-extract-al16-al8.h new file mode 100644 index 0000000..31b6fe8 --- /dev/null +++ b/host/include/x86_64/host/load-extract-al16-al8.h @@ -0,0 +1,50 @@ +/* + * SPDX-License-Identifier: GPL-2.0-or-later + * Atomic extract 64 from 128-bit, x86_64 version. + * + * Copyright (C) 2023 Linaro, Ltd. + */ + +#ifndef X86_64_LOAD_EXTRACT_AL16_AL8_H +#define X86_64_LOAD_EXTRACT_AL16_AL8_H + +#ifdef CONFIG_INT128_TYPE +#include "host/cpuinfo.h" + +/** + * load_atom_extract_al16_or_al8: + * @pv: host address + * @s: object size in bytes, @s <= 8. + * + * Load @s bytes from @pv, when pv % s != 0. If [p, p+s-1] does not + * cross an 16-byte boundary then the access must be 16-byte atomic, + * otherwise the access must be 8-byte atomic. + */ +static inline uint64_t ATTRIBUTE_ATOMIC128_OPT +load_atom_extract_al16_or_al8(void *pv, int s) +{ + uintptr_t pi = (uintptr_t)pv; + __int128_t *ptr_align = (__int128_t *)(pi & ~7); + int shr = (pi & 7) * 8; + Int128Alias r; + + /* + * ptr_align % 16 is now only 0 or 8. + * If the host supports atomic loads with VMOVDQU, then always use that, + * making the branch highly predictable. Otherwise we must use VMOVDQA + * when ptr_align % 16 == 0 for 16-byte atomicity. + */ + if ((cpuinfo & CPUINFO_ATOMIC_VMOVDQU) || (pi & 8)) { + asm("vmovdqu %1, %0" : "=x" (r.i) : "m" (*ptr_align)); + } else { + asm("vmovdqa %1, %0" : "=x" (r.i) : "m" (*ptr_align)); + } + return int128_getlo(int128_urshift(r.s, shr)); +} +#else +/* Fallback definition that must be optimized away, or error. */ +uint64_t QEMU_ERROR("unsupported atomic") + load_atom_extract_al16_or_al8(void *pv, int s); +#endif + +#endif /* X86_64_LOAD_EXTRACT_AL16_AL8_H */ |