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92a0ff1e1e
On Android /proc/self/auxv is not readable, leading to a panic in init. Instead of panic'ing in this case, introduce the Initialized global bool to report whether the CPU features were initialized i.e. /proc/self/auxv was successfullly read. Fixes golang/go#30413 Change-Id: Ib520f202990614a76bceb0bf9d19a88eadd13e10 Reviewed-on: https://go-review.googlesource.com/c/164057 Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org>
60 lines
1.1 KiB
Go
60 lines
1.1 KiB
Go
// 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 !amd64,!amd64p32,!386
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package cpu
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import (
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"io/ioutil"
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)
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const (
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_AT_HWCAP = 16
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_AT_HWCAP2 = 26
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procAuxv = "/proc/self/auxv"
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uintSize = int(32 << (^uint(0) >> 63))
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)
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// For those platforms don't have a 'cpuid' equivalent we use HWCAP/HWCAP2
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// These are initialized in cpu_$GOARCH.go
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// and should not be changed after they are initialized.
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var hwCap uint
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var hwCap2 uint
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func init() {
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buf, err := ioutil.ReadFile(procAuxv)
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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
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return
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}
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bo := hostByteOrder()
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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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hwCap2 = val
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}
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}
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doinit()
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Initialized = true
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}
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