gojit的应用小应用，参考这编文章，今年写个jit to ebpf vm

[laik]

https://www.readfog.com/a/1641161516770234368 https://medium.com/kokster/writing-a-jit-compiler-in-golang-964b61295f

简单的jit代码。 syscall.Mmap(）

package main

import (
 "fmt"
 "syscall"
 "unsafe"
)

type printFunc func()

func main() {
 printFunction := []uint16{
  0x48c7, 0xc001, 0x0, // mov %rax,$0x1
  0x48, 0xc7c7, 0x100, 0x0, // mov %rdi,$0x1
  0x48c7, 0xc20c, 0x0, // mov 0x13, %rdx
  0x48, 0x8d35, 0x400, 0x0, // lea 0x4(%rip), %rsi
  0xf05,                  // syscall
  0xc3cc,                 // ret
  0x4865, 0x6c6c, 0x6f20, // Hello_(whitespace)
  0x576f, 0x726c, 0x6421, 0xa, // World!
 }
 executablePrintFunc, err := syscall.Mmap(
  -1,
  0,
  128,
  syscall.PROT_READ|syscall.PROT_WRITE|syscall.PROT_EXEC,
  syscall.MAP_PRIVATE|syscall.MAP_ANONYMOUS)
 if err != nil {
  fmt.Printf("mmap err: %v", err)
 }

 j := 0
 for i := range printFunction {
  executablePrintFunc[j] = byte(printFunction[i] >> 8)
  executablePrintFunc[j+1] = byte(printFunction[i])
  j = j + 2
 }

 type printFunc func()

 unsafePrintFunc := (uintptr)(unsafe.Pointer(&executablePrintFunc))
 printer := *(*printFunc)(unsafe.Pointer(&unsafePrintFunc))
 printer()
}