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85b82a3add
This allows to detect ARM64 CPU features on non-Linux systems. On Linux, this is used in case /proc/self/auxv cannot be read. Change-Id: I67d55e989f2beda0c05a97ca5e55781840a8e01c Reviewed-on: https://go-review.googlesource.com/c/sys/+/209478 Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org>
44 lines
1.2 KiB
C
44 lines
1.2 KiB
C
// Copyright 2018 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// +build 386 amd64 amd64p32
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// +build gccgo
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#include <cpuid.h>
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#include <stdint.h>
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// Need to wrap __get_cpuid_count because it's declared as static.
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int
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gccgoGetCpuidCount(uint32_t leaf, uint32_t subleaf,
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uint32_t *eax, uint32_t *ebx,
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uint32_t *ecx, uint32_t *edx)
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{
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return __get_cpuid_count(leaf, subleaf, eax, ebx, ecx, edx);
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}
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// xgetbv reads the contents of an XCR (Extended Control Register)
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// specified in the ECX register into registers EDX:EAX.
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// Currently, the only supported value for XCR is 0.
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//
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// TODO: Replace with a better alternative:
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//
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// #include <xsaveintrin.h>
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//
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// #pragma GCC target("xsave")
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//
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// void gccgoXgetbv(uint32_t *eax, uint32_t *edx) {
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// unsigned long long x = _xgetbv(0);
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// *eax = x & 0xffffffff;
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// *edx = (x >> 32) & 0xffffffff;
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// }
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//
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// Note that _xgetbv is defined starting with GCC 8.
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void
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gccgoXgetbv(uint32_t *eax, uint32_t *edx)
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{
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__asm(" xorl %%ecx, %%ecx\n"
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" xgetbv"
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: "=a"(*eax), "=d"(*edx));
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}
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