131 lines
3.9 KiB
Go
131 lines
3.9 KiB
Go
// Copyright (c) 2020 Klaus Post, released under MIT License. See LICENSE file.
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// 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 located
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// here https://github.com/golang/sys/blob/master/LICENSE
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package cpuid
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import (
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"encoding/binary"
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"io/ioutil"
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"runtime"
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)
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// HWCAP bits.
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const (
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hwcap_FP = 1 << 0
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hwcap_ASIMD = 1 << 1
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hwcap_EVTSTRM = 1 << 2
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hwcap_AES = 1 << 3
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hwcap_PMULL = 1 << 4
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hwcap_SHA1 = 1 << 5
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hwcap_SHA2 = 1 << 6
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hwcap_CRC32 = 1 << 7
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hwcap_ATOMICS = 1 << 8
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hwcap_FPHP = 1 << 9
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hwcap_ASIMDHP = 1 << 10
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hwcap_CPUID = 1 << 11
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hwcap_ASIMDRDM = 1 << 12
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hwcap_JSCVT = 1 << 13
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hwcap_FCMA = 1 << 14
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hwcap_LRCPC = 1 << 15
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hwcap_DCPOP = 1 << 16
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hwcap_SHA3 = 1 << 17
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hwcap_SM3 = 1 << 18
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hwcap_SM4 = 1 << 19
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hwcap_ASIMDDP = 1 << 20
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hwcap_SHA512 = 1 << 21
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hwcap_SVE = 1 << 22
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hwcap_ASIMDFHM = 1 << 23
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)
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func detectOS(c *CPUInfo) bool {
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// For now assuming no hyperthreading is reasonable.
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c.LogicalCores = runtime.NumCPU()
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c.PhysicalCores = c.LogicalCores
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c.ThreadsPerCore = 1
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if hwcap == 0 {
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// We did not get values from the runtime.
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// Try reading /proc/self/auxv
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// From https://github.com/golang/sys
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const (
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_AT_HWCAP = 16
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_AT_HWCAP2 = 26
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uintSize = int(32 << (^uint(0) >> 63))
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)
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buf, err := ioutil.ReadFile("/proc/self/auxv")
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if err != nil {
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// e.g. on android /proc/self/auxv is not accessible, so silently
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// ignore the error and leave Initialized = false. On some
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// architectures (e.g. arm64) doinit() implements a fallback
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// readout and will set Initialized = true again.
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return false
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}
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bo := binary.LittleEndian
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for len(buf) >= 2*(uintSize/8) {
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var tag, val uint
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switch uintSize {
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case 32:
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tag = uint(bo.Uint32(buf[0:]))
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val = uint(bo.Uint32(buf[4:]))
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buf = buf[8:]
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case 64:
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tag = uint(bo.Uint64(buf[0:]))
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val = uint(bo.Uint64(buf[8:]))
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buf = buf[16:]
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}
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switch tag {
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case _AT_HWCAP:
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hwcap = val
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case _AT_HWCAP2:
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// Not used
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}
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}
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if hwcap == 0 {
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return false
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}
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}
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// HWCap was populated by the runtime from the auxiliary vector.
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// Use HWCap information since reading aarch64 system registers
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// is not supported in user space on older linux kernels.
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c.featureSet.setIf(isSet(hwcap, hwcap_AES), AESARM)
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c.featureSet.setIf(isSet(hwcap, hwcap_ASIMD), ASIMD)
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c.featureSet.setIf(isSet(hwcap, hwcap_ASIMDDP), ASIMDDP)
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c.featureSet.setIf(isSet(hwcap, hwcap_ASIMDHP), ASIMDHP)
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c.featureSet.setIf(isSet(hwcap, hwcap_ASIMDRDM), ASIMDRDM)
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c.featureSet.setIf(isSet(hwcap, hwcap_CPUID), ARMCPUID)
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c.featureSet.setIf(isSet(hwcap, hwcap_CRC32), CRC32)
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c.featureSet.setIf(isSet(hwcap, hwcap_DCPOP), DCPOP)
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c.featureSet.setIf(isSet(hwcap, hwcap_EVTSTRM), EVTSTRM)
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c.featureSet.setIf(isSet(hwcap, hwcap_FCMA), FCMA)
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c.featureSet.setIf(isSet(hwcap, hwcap_FP), FP)
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c.featureSet.setIf(isSet(hwcap, hwcap_FPHP), FPHP)
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c.featureSet.setIf(isSet(hwcap, hwcap_JSCVT), JSCVT)
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c.featureSet.setIf(isSet(hwcap, hwcap_LRCPC), LRCPC)
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c.featureSet.setIf(isSet(hwcap, hwcap_PMULL), PMULL)
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c.featureSet.setIf(isSet(hwcap, hwcap_SHA1), SHA1)
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c.featureSet.setIf(isSet(hwcap, hwcap_SHA2), SHA2)
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c.featureSet.setIf(isSet(hwcap, hwcap_SHA3), SHA3)
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c.featureSet.setIf(isSet(hwcap, hwcap_SHA512), SHA512)
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c.featureSet.setIf(isSet(hwcap, hwcap_SM3), SM3)
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c.featureSet.setIf(isSet(hwcap, hwcap_SM4), SM4)
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c.featureSet.setIf(isSet(hwcap, hwcap_SVE), SVE)
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// The Samsung S9+ kernel reports support for atomics, but not all cores
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// actually support them, resulting in SIGILL. See issue #28431.
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// TODO(elias.naur): Only disable the optimization on bad chipsets on android.
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c.featureSet.setIf(isSet(hwcap, hwcap_ATOMICS) && runtime.GOOS != "android", ATOMICS)
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return true
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}
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func isSet(hwc uint, value uint) bool {
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return hwc&value != 0
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}
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