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package platform
import (
"math/bits"
"os"
"sort"
"strconv"
"strings"
"syscall"
)
const (
// https://man7.org/linux/man-pages/man2/mmap.2.html
__MAP_HUGE_SHIFT = 26
__MAP_HUGETLB = 0x40000
)
var hugePagesConfigs []hugePagesConfig
type hugePagesConfig struct {
size int
flag int
}
func (hpc *hugePagesConfig) match(size int) bool {
return (size & (hpc.size - 1)) == 0
}
func init() {
dirents, err := os.ReadDir("/sys/kernel/mm/hugepages/")
if err != nil {
return
}
for _, dirent := range dirents {
name := dirent.Name()
if !strings.HasPrefix(name, "hugepages-") {
continue
}
if !strings.HasSuffix(name, "kB") {
continue
}
n, err := strconv.ParseUint(name[10:len(name)-2], 10, 64)
if err != nil {
continue
}
if bits.OnesCount64(n) != 1 {
continue
}
n *= 1024
hugePagesConfigs = append(hugePagesConfigs, hugePagesConfig{
size: int(n),
flag: int(bits.TrailingZeros64(n)<<__MAP_HUGE_SHIFT) | __MAP_HUGETLB,
})
}
sort.Slice(hugePagesConfigs, func(i, j int) bool {
return hugePagesConfigs[i].size > hugePagesConfigs[j].size
})
}
func mmapCodeSegment(size, prot int) ([]byte, error) {
flags := syscall.MAP_ANON | syscall.MAP_PRIVATE
for _, hugePagesConfig := range hugePagesConfigs {
if hugePagesConfig.match(size) {
b, err := syscall.Mmap(-1, 0, size, prot, flags|hugePagesConfig.flag)
if err != nil {
continue
}
return b, nil
}
}
return syscall.Mmap(-1, 0, size, prot, flags)
}
|
