2019-04-29 21:25:05 +00:00
|
|
|
// Copyright 2018 The gVisor Authors.
|
2018-04-27 17:37:02 +00:00
|
|
|
//
|
|
|
|
// Licensed under the Apache License, Version 2.0 (the "License");
|
|
|
|
// you may not use this file except in compliance with the License.
|
|
|
|
// You may obtain a copy of the License at
|
|
|
|
//
|
|
|
|
// http://www.apache.org/licenses/LICENSE-2.0
|
|
|
|
//
|
|
|
|
// Unless required by applicable law or agreed to in writing, software
|
|
|
|
// distributed under the License is distributed on an "AS IS" BASIS,
|
|
|
|
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
|
|
// See the License for the specific language governing permissions and
|
|
|
|
// limitations under the License.
|
|
|
|
|
|
|
|
// Package hostcpu provides utilities for working with CPU information provided
|
|
|
|
// by a host Linux kernel.
|
|
|
|
package hostcpu
|
|
|
|
|
|
|
|
import (
|
|
|
|
"fmt"
|
|
|
|
"io/ioutil"
|
|
|
|
"strconv"
|
|
|
|
"strings"
|
|
|
|
"unicode"
|
|
|
|
)
|
|
|
|
|
|
|
|
// GetCPU returns the caller's current CPU number, without using the Linux VDSO
|
|
|
|
// (which is not available to the sentry) or the getcpu(2) system call (which
|
|
|
|
// is relatively slow).
|
|
|
|
func GetCPU() uint32
|
|
|
|
|
|
|
|
// MaxPossibleCPU returns the highest possible CPU number, which is guaranteed
|
|
|
|
// not to change for the lifetime of the host kernel.
|
|
|
|
func MaxPossibleCPU() (uint32, error) {
|
|
|
|
const path = "/sys/devices/system/cpu/possible"
|
|
|
|
data, err := ioutil.ReadFile(path)
|
|
|
|
if err != nil {
|
|
|
|
return 0, err
|
|
|
|
}
|
|
|
|
str := string(data)
|
|
|
|
// Linux: drivers/base/cpu.c:show_cpus_attr() =>
|
|
|
|
// include/linux/cpumask.h:cpumask_print_to_pagebuf() =>
|
|
|
|
// lib/bitmap.c:bitmap_print_to_pagebuf()
|
|
|
|
i, err := maxValueInLinuxBitmap(str)
|
|
|
|
if err != nil {
|
|
|
|
return 0, fmt.Errorf("invalid %s (%q): %v", path, str, err)
|
|
|
|
}
|
|
|
|
return uint32(i), nil
|
|
|
|
}
|
|
|
|
|
|
|
|
// maxValueInLinuxBitmap returns the maximum value specified in str, which is a
|
|
|
|
// string emitted by Linux's lib/bitmap.c:bitmap_print_to_pagebuf(list=true).
|
|
|
|
func maxValueInLinuxBitmap(str string) (uint64, error) {
|
|
|
|
str = strings.TrimSpace(str)
|
|
|
|
// Find the last decimal number in str.
|
|
|
|
idx := strings.LastIndexFunc(str, func(c rune) bool {
|
|
|
|
return !unicode.IsDigit(c)
|
|
|
|
})
|
|
|
|
if idx != -1 {
|
|
|
|
str = str[idx+1:]
|
|
|
|
}
|
|
|
|
i, err := strconv.ParseUint(str, 10, 64)
|
|
|
|
if err != nil {
|
|
|
|
return 0, err
|
|
|
|
}
|
|
|
|
return i, nil
|
|
|
|
}
|