cmd/bpa-operator/vendor/golang.org/x/sys/cpu/cpu_linux.go

   1 // Copyright 2018 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 //+build !amd64,!amd64p32,!386
   6
   7 package cpu
   8
   9 import (
  10         "io/ioutil"
  11 )
  12
  13 const (
  14         _AT_HWCAP  = 16
  15         _AT_HWCAP2 = 26
  16
  17         procAuxv = "/proc/self/auxv"
  18
  19         uintSize = int(32 << (^uint(0) >> 63))
  20 )
  21
  22 // For those platforms don't have a 'cpuid' equivalent we use HWCAP/HWCAP2
  23 // These are initialized in cpu_$GOARCH.go
  24 // and should not be changed after they are initialized.
  25 var hwCap uint
  26 var hwCap2 uint
  27
  28 func init() {
  29         buf, err := ioutil.ReadFile(procAuxv)
  30         if err != nil {
  31                 // e.g. on android /proc/self/auxv is not accessible, so silently
  32                 // ignore the error and leave Initialized = false
  33                 return
  34         }
  35
  36         bo := hostByteOrder()
  37         for len(buf) >= 2*(uintSize/8) {
  38                 var tag, val uint
  39                 switch uintSize {
  40                 case 32:
  41                         tag = uint(bo.Uint32(buf[0:]))
  42                         val = uint(bo.Uint32(buf[4:]))
  43                         buf = buf[8:]
  44                 case 64:
  45                         tag = uint(bo.Uint64(buf[0:]))
  46                         val = uint(bo.Uint64(buf[8:]))
  47                         buf = buf[16:]
  48                 }
  49                 switch tag {
  50                 case _AT_HWCAP:
  51                         hwCap = val
  52                 case _AT_HWCAP2:
  53                         hwCap2 = val
  54                 }
  55         }
  56         doinit()
  57
  58         Initialized = true
  59 }