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// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package cpu
import (
"strings"
"syscall"
)
// HWCAP/HWCAP2 bits. These are exposed by Linux.
const (
hwcap_FP = 1 << 0
hwcap_ASIMD = 1 << 1
hwcap_EVTSTRM = 1 << 2
hwcap_AES = 1 << 3
hwcap_PMULL = 1 << 4
hwcap_SHA1 = 1 << 5
hwcap_SHA2 = 1 << 6
hwcap_CRC32 = 1 << 7
hwcap_ATOMICS = 1 << 8
hwcap_FPHP = 1 << 9
hwcap_ASIMDHP = 1 << 10
hwcap_CPUID = 1 << 11
hwcap_ASIMDRDM = 1 << 12
hwcap_JSCVT = 1 << 13
hwcap_FCMA = 1 << 14
hwcap_LRCPC = 1 << 15
hwcap_DCPOP = 1 << 16
hwcap_SHA3 = 1 << 17
hwcap_SM3 = 1 << 18
hwcap_SM4 = 1 << 19
hwcap_ASIMDDP = 1 << 20
hwcap_SHA512 = 1 << 21
hwcap_SVE = 1 << 22
hwcap_ASIMDFHM = 1 << 23
)
// linuxKernelCanEmulateCPUID reports whether we're running
// on Linux 4.11+. Ideally we'd like to ask the question about
// whether the current kernel contains
// https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=77c97b4ee21290f5f083173d957843b615abbff2
// but the version number will have to do.
func linuxKernelCanEmulateCPUID() bool {
var un syscall.Utsname
syscall.Uname(&un)
var sb strings.Builder
for _, b := range un.Release[:] {
if b == 0 {
break
}
sb.WriteByte(byte(b))
}
major, minor, _, ok := parseRelease(sb.String())
return ok && (major > 4 || major == 4 && minor >= 11)
}
func doinit() {
if err := readHWCAP(); err != nil {
// We failed to read /proc/self/auxv. This can happen if the binary has
// been given extra capabilities(7) with /bin/setcap.
//
// When this happens, we have two options. If the Linux kernel is new
// enough (4.11+), we can read the arm64 registers directly which'll
// trap into the kernel and then return back to userspace.
//
// But on older kernels, such as Linux 4.4.180 as used on many Synology
// devices, calling readARM64Registers (specifically getisar0) will
// cause a SIGILL and we'll die. So for older kernels, parse /proc/cpuinfo
// instead.
//
// See golang/go#57336.
if linuxKernelCanEmulateCPUID() {
readARM64Registers()
} else {
readLinuxProcCPUInfo()
}
return
}
// HWCAP feature bits
ARM64.HasFP = isSet(hwCap, hwcap_FP)
ARM64.HasASIMD = isSet(hwCap, hwcap_ASIMD)
ARM64.HasEVTSTRM = isSet(hwCap, hwcap_EVTSTRM)
ARM64.HasAES = isSet(hwCap, hwcap_AES)
ARM64.HasPMULL = isSet(hwCap, hwcap_PMULL)
ARM64.HasSHA1 = isSet(hwCap, hwcap_SHA1)
ARM64.HasSHA2 = isSet(hwCap, hwcap_SHA2)
ARM64.HasCRC32 = isSet(hwCap, hwcap_CRC32)
ARM64.HasATOMICS = isSet(hwCap, hwcap_ATOMICS)
ARM64.HasFPHP = isSet(hwCap, hwcap_FPHP)
ARM64.HasASIMDHP = isSet(hwCap, hwcap_ASIMDHP)
ARM64.HasCPUID = isSet(hwCap, hwcap_CPUID)
ARM64.HasASIMDRDM = isSet(hwCap, hwcap_ASIMDRDM)
ARM64.HasJSCVT = isSet(hwCap, hwcap_JSCVT)
ARM64.HasFCMA = isSet(hwCap, hwcap_FCMA)
ARM64.HasLRCPC = isSet(hwCap, hwcap_LRCPC)
ARM64.HasDCPOP = isSet(hwCap, hwcap_DCPOP)
ARM64.HasSHA3 = isSet(hwCap, hwcap_SHA3)
ARM64.HasSM3 = isSet(hwCap, hwcap_SM3)
ARM64.HasSM4 = isSet(hwCap, hwcap_SM4)
ARM64.HasASIMDDP = isSet(hwCap, hwcap_ASIMDDP)
ARM64.HasSHA512 = isSet(hwCap, hwcap_SHA512)
ARM64.HasSVE = isSet(hwCap, hwcap_SVE)
ARM64.HasASIMDFHM = isSet(hwCap, hwcap_ASIMDFHM)
}
func isSet(hwc uint, value uint) bool {
return hwc&value != 0
}
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