loader.go (1926B)
1 //go:build darwin || linux 2 // +build darwin linux 3 4 /* 5 * Copyright 2021 ByteDance Inc. 6 * 7 * Licensed under the Apache License, Version 2.0 (the "License"); 8 * you may not use this file except in compliance with the License. 9 * You may obtain a copy of the License at 10 * 11 * http://www.apache.org/licenses/LICENSE-2.0 12 * 13 * Unless required by applicable law or agreed to in writing, software 14 * distributed under the License is distributed on an "AS IS" BASIS, 15 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 16 * See the License for the specific language governing permissions and 17 * limitations under the License. 18 */ 19 20 package loader 21 22 import ( 23 `fmt` 24 `os` 25 `reflect` 26 `syscall` 27 `unsafe` 28 ) 29 30 const ( 31 _AP = syscall.MAP_ANON | syscall.MAP_PRIVATE 32 _RX = syscall.PROT_READ | syscall.PROT_EXEC 33 _RW = syscall.PROT_READ | syscall.PROT_WRITE 34 ) 35 36 type Loader []byte 37 type Function unsafe.Pointer 38 39 func (self Loader) Load(fn string, fp int, args int, argPtrs []bool, localPtrs []bool) (f Function) { 40 p := os.Getpagesize() 41 n := (((len(self) - 1) / p) + 1) * p 42 43 /* register the function */ 44 m := mmap(n) 45 v := fmt.Sprintf("runtime.__%s_%x", fn, m) 46 47 registerFunction(v, m, uintptr(n), fp, args, uintptr(len(self)), argPtrs, localPtrs) 48 49 /* reference as a slice */ 50 s := *(*[]byte)(unsafe.Pointer(&reflect.SliceHeader { 51 Data : m, 52 Cap : n, 53 Len : len(self), 54 })) 55 56 /* copy the machine code, and make it executable */ 57 copy(s, self) 58 mprotect(m, n) 59 return Function(&m) 60 } 61 62 func mmap(nb int) uintptr { 63 if m, _, e := syscall.RawSyscall6(syscall.SYS_MMAP, 0, uintptr(nb), _RW, _AP, 0, 0); e != 0 { 64 panic(e) 65 } else { 66 return m 67 } 68 } 69 70 func mprotect(p uintptr, nb int) { 71 if _, _, err := syscall.RawSyscall(syscall.SYS_MPROTECT, p, uintptr(nb), _RX); err != 0 { 72 panic(err) 73 } 74 }