whatcanGOwrong

go/pkg/mod/golang.org/x/sys@v0.17.0/unix/mkasm.go

@@ -0,0 +1,137 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build ignore
+
+// mkasm.go generates assembly trampolines to call library routines from Go.
+// This program must be run after mksyscall.go.
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"log"
+	"os"
+	"sort"
+	"strings"
+)
+
+func archPtrSize(arch string) int {
+	switch arch {
+	case "386", "arm":
+		return 4
+	case "amd64", "arm64", "mips64", "ppc64", "riscv64":
+		return 8
+	default:
+		log.Fatalf("Unknown arch %q", arch)
+		return 0
+	}
+}
+
+func generateASMFile(goos, arch string, inFileNames []string, outFileName string) map[string]bool {
+	trampolines := map[string]bool{}
+	var orderedTrampolines []string
+	for _, inFileName := range inFileNames {
+		in, err := os.ReadFile(inFileName)
+		if err != nil {
+			log.Fatalf("Failed to read file: %v", err)
+		}
+		for _, line := range strings.Split(string(in), "\n") {
+			const prefix = "var "
+			const suffix = "_trampoline_addr uintptr"
+			if !strings.HasPrefix(line, prefix) || !strings.HasSuffix(line, suffix) {
+				continue
+			}
+			fn := strings.TrimSuffix(strings.TrimPrefix(line, prefix), suffix)
+			if !trampolines[fn] {
+				orderedTrampolines = append(orderedTrampolines, fn)
+				trampolines[fn] = true
+			}
+		}
+	}
+
+	ptrSize := archPtrSize(arch)
+
+	var out bytes.Buffer
+	fmt.Fprintf(&out, "// go run mkasm.go %s\n", strings.Join(os.Args[1:], " "))
+	fmt.Fprintf(&out, "// Code generated by the command above; DO NOT EDIT.\n")
+	fmt.Fprintf(&out, "\n")
+	fmt.Fprintf(&out, "#include \"textflag.h\"\n")
+	for _, fn := range orderedTrampolines {
+		fmt.Fprintf(&out, "\nTEXT %s_trampoline<>(SB),NOSPLIT,$0-0\n", fn)
+		if goos == "openbsd" && arch == "ppc64" {
+			fmt.Fprintf(&out, "\tCALL\t%s(SB)\n", fn)
+			fmt.Fprintf(&out, "\tRET\n")
+		} else {
+			fmt.Fprintf(&out, "\tJMP\t%s(SB)\n", fn)
+		}
+		fmt.Fprintf(&out, "GLOBL\t·%s_trampoline_addr(SB), RODATA, $%d\n", fn, ptrSize)
+		fmt.Fprintf(&out, "DATA\t·%s_trampoline_addr(SB)/%d, $%s_trampoline<>(SB)\n", fn, ptrSize, fn)
+	}
+
+	if err := os.WriteFile(outFileName, out.Bytes(), 0644); err != nil {
+		log.Fatalf("Failed to write assembly file %q: %v", outFileName, err)
+	}
+
+	return trampolines
+}
+
+const darwinTestTemplate = `// go run mkasm.go %s
+// Code generated by the command above; DO NOT EDIT.
+
+//go:build darwin && go1.12
+
+package unix
+
+// All the _trampoline functions in zsyscall_darwin_%s.s.
+var darwinTests = [...]darwinTest{
+%s}
+`
+
+func writeDarwinTest(trampolines map[string]bool, fileName, arch string) {
+	var sortedTrampolines []string
+	for fn := range trampolines {
+		sortedTrampolines = append(sortedTrampolines, fn)
+	}
+	sort.Strings(sortedTrampolines)
+
+	var out bytes.Buffer
+
+	const prefix = "libc_"
+	for _, fn := range sortedTrampolines {
+		fmt.Fprintf(&out, fmt.Sprintf("\t{%q, %s_trampoline_addr},\n", strings.TrimPrefix(fn, prefix), fn))
+	}
+	lines := out.String()
+
+	out.Reset()
+	fmt.Fprintf(&out, darwinTestTemplate, strings.Join(os.Args[1:], " "), arch, lines)
+
+	if err := os.WriteFile(fileName, out.Bytes(), 0644); err != nil {
+		log.Fatalf("Failed to write test file %q: %v", fileName, err)
+	}
+}
+
+func main() {
+	if len(os.Args) != 3 {
+		log.Fatalf("Usage: %s <goos> <arch>", os.Args[0])
+	}
+	goos, arch := os.Args[1], os.Args[2]
+
+	syscallFilename := fmt.Sprintf("syscall_%s.go", goos)
+	syscallArchFilename := fmt.Sprintf("syscall_%s_%s.go", goos, arch)
+	zsyscallArchFilename := fmt.Sprintf("zsyscall_%s_%s.go", goos, arch)
+	zsyscallASMFileName := fmt.Sprintf("zsyscall_%s_%s.s", goos, arch)
+
+	inFileNames := []string{
+		syscallFilename,
+		syscallArchFilename,
+		zsyscallArchFilename,
+	}
+
+	trampolines := generateASMFile(goos, arch, inFileNames, zsyscallASMFileName)
+
+	if goos == "darwin" {
+		writeDarwinTest(trampolines, fmt.Sprintf("darwin_%s_test.go", arch), arch)
+	}
+}