github.com/neonyo/sys@v0.0.0-20230720094341-b1ee14be3ce8/unix/mkasm.go (about)

     1  // Copyright 2018 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  //go:build ignore
     6  // +build ignore
     7  
     8  // mkasm.go generates assembly trampolines to call library routines from Go.
     9  // This program must be run after mksyscall.go.
    10  package main
    11  
    12  import (
    13  	"bytes"
    14  	"fmt"
    15  	"io/ioutil"
    16  	"log"
    17  	"os"
    18  	"sort"
    19  	"strings"
    20  )
    21  
    22  func archPtrSize(arch string) int {
    23  	switch arch {
    24  	case "386", "arm":
    25  		return 4
    26  	case "amd64", "arm64", "mips64", "ppc64", "riscv64":
    27  		return 8
    28  	default:
    29  		log.Fatalf("Unknown arch %q", arch)
    30  		return 0
    31  	}
    32  }
    33  
    34  func generateASMFile(goos, arch string, inFileNames []string, outFileName string) map[string]bool {
    35  	trampolines := map[string]bool{}
    36  	var orderedTrampolines []string
    37  	for _, inFileName := range inFileNames {
    38  		in, err := ioutil.ReadFile(inFileName)
    39  		if err != nil {
    40  			log.Fatalf("Failed to read file: %v", err)
    41  		}
    42  		for _, line := range strings.Split(string(in), "\n") {
    43  			const prefix = "var "
    44  			const suffix = "_trampoline_addr uintptr"
    45  			if !strings.HasPrefix(line, prefix) || !strings.HasSuffix(line, suffix) {
    46  				continue
    47  			}
    48  			fn := strings.TrimSuffix(strings.TrimPrefix(line, prefix), suffix)
    49  			if !trampolines[fn] {
    50  				orderedTrampolines = append(orderedTrampolines, fn)
    51  				trampolines[fn] = true
    52  			}
    53  		}
    54  	}
    55  
    56  	ptrSize := archPtrSize(arch)
    57  
    58  	var out bytes.Buffer
    59  	fmt.Fprintf(&out, "// go run mkasm.go %s\n", strings.Join(os.Args[1:], " "))
    60  	fmt.Fprintf(&out, "// Code generated by the command above; DO NOT EDIT.\n")
    61  	fmt.Fprintf(&out, "\n")
    62  	fmt.Fprintf(&out, "#include \"textflag.h\"\n")
    63  	for _, fn := range orderedTrampolines {
    64  		fmt.Fprintf(&out, "\nTEXT %s_trampoline<>(SB),NOSPLIT,$0-0\n", fn)
    65  		if goos == "openbsd" && arch == "ppc64" {
    66  			fmt.Fprintf(&out, "\tCALL\t%s(SB)\n", fn)
    67  			fmt.Fprintf(&out, "\tRET\n")
    68  		} else {
    69  			fmt.Fprintf(&out, "\tJMP\t%s(SB)\n", fn)
    70  		}
    71  		fmt.Fprintf(&out, "GLOBL\t·%s_trampoline_addr(SB), RODATA, $%d\n", fn, ptrSize)
    72  		fmt.Fprintf(&out, "DATA\t·%s_trampoline_addr(SB)/%d, $%s_trampoline<>(SB)\n", fn, ptrSize, fn)
    73  	}
    74  
    75  	if err := ioutil.WriteFile(outFileName, out.Bytes(), 0644); err != nil {
    76  		log.Fatalf("Failed to write assembly file %q: %v", outFileName, err)
    77  	}
    78  
    79  	return trampolines
    80  }
    81  
    82  const darwinTestTemplate = `// go run mkasm.go %s
    83  // Code generated by the command above; DO NOT EDIT.
    84  
    85  //go:build darwin && go1.12
    86  // +build darwin,go1.12
    87  
    88  package unix
    89  
    90  // All the _trampoline functions in zsyscall_darwin_%s.s.
    91  var darwinTests = [...]darwinTest{
    92  %s}
    93  `
    94  
    95  func writeDarwinTest(trampolines map[string]bool, fileName, arch string) {
    96  	var sortedTrampolines []string
    97  	for fn := range trampolines {
    98  		sortedTrampolines = append(sortedTrampolines, fn)
    99  	}
   100  	sort.Strings(sortedTrampolines)
   101  
   102  	var out bytes.Buffer
   103  
   104  	const prefix = "libc_"
   105  	for _, fn := range sortedTrampolines {
   106  		fmt.Fprintf(&out, fmt.Sprintf("\t{%q, %s_trampoline_addr},\n", strings.TrimPrefix(fn, prefix), fn))
   107  	}
   108  	lines := out.String()
   109  
   110  	out.Reset()
   111  	fmt.Fprintf(&out, darwinTestTemplate, strings.Join(os.Args[1:], " "), arch, lines)
   112  
   113  	if err := ioutil.WriteFile(fileName, out.Bytes(), 0644); err != nil {
   114  		log.Fatalf("Failed to write test file %q: %v", fileName, err)
   115  	}
   116  }
   117  
   118  func main() {
   119  	if len(os.Args) != 3 {
   120  		log.Fatalf("Usage: %s <goos> <arch>", os.Args[0])
   121  	}
   122  	goos, arch := os.Args[1], os.Args[2]
   123  
   124  	syscallFilename := fmt.Sprintf("syscall_%s.go", goos)
   125  	syscallArchFilename := fmt.Sprintf("syscall_%s_%s.go", goos, arch)
   126  	zsyscallArchFilename := fmt.Sprintf("zsyscall_%s_%s.go", goos, arch)
   127  	zsyscallASMFileName := fmt.Sprintf("zsyscall_%s_%s.s", goos, arch)
   128  
   129  	inFileNames := []string{
   130  		syscallFilename,
   131  		syscallArchFilename,
   132  		zsyscallArchFilename,
   133  	}
   134  
   135  	trampolines := generateASMFile(goos, arch, inFileNames, zsyscallASMFileName)
   136  
   137  	if goos == "darwin" {
   138  		writeDarwinTest(trampolines, fmt.Sprintf("darwin_%s_test.go", arch), arch)
   139  	}
   140  }