85 lines
2.5 KiB
Go
85 lines
2.5 KiB
Go
// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
|
|
// SPDX-License-Identifier: BSD-3-Clause
|
|
|
|
package asm
|
|
|
|
import (
|
|
"bytes"
|
|
"fmt"
|
|
"os"
|
|
"os/exec"
|
|
"path/filepath"
|
|
"sync"
|
|
)
|
|
|
|
// GOObjectAARCH64 emits a GOOBJ object file for AArch64. The layout is
|
|
// the shared one in goobj.go — the toolchain preamble, the go120ld header
|
|
// with its block offsets, the string table, the symbol definitions and the
|
|
// reloc/aux/data index arrays — with the arm64 preamble, the MinLC of 4
|
|
// for the pc-value deltas, and R_ADDRARM64 relocation types for the
|
|
// ADRP+ADD/LDR/STR address pairs.
|
|
func (img *Image) GOObjectAARCH64(pkgPath, srcPath string) ([]byte, error) {
|
|
pre, err := toolchainObjectPreambleAARCH64()
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
return img.emitGOObject(pkgPath, srcPath, pre, 4, func(r Reloc) (uint16, uint8) {
|
|
return relocArm64Addr, 4
|
|
})
|
|
}
|
|
|
|
// arm64 relocation types (cmd/internal/objabi). R_ADDRARM64 resolves an
|
|
// ADRP+ADD/LDR/STR pair to a symbol's address.
|
|
const (
|
|
relocArm64Addr = 9 // R_ADDRARM64
|
|
)
|
|
|
|
// toolchainObjectPreambleAARCH64 returns the "go object ...\n!\n" header
|
|
// the installed go tool asm writes for arm64, captured by assembling a
|
|
// one-instruction probe.
|
|
var (
|
|
preambleAARCH64Once sync.Once
|
|
preambleAARCH64 []byte
|
|
preambleAARCH64Err error
|
|
)
|
|
|
|
func toolchainObjectPreambleAARCH64() ([]byte, error) {
|
|
preambleAARCH64Once.Do(func() {
|
|
goBin, err := exec.LookPath("go")
|
|
if err != nil {
|
|
preambleAARCH64Err = fmt.Errorf("GOOBJ emission needs the Go toolchain: %w", err)
|
|
return
|
|
}
|
|
dir, err := os.MkdirTemp("", "gasm-preamble-arm64")
|
|
if err != nil {
|
|
preambleAARCH64Err = err
|
|
return
|
|
}
|
|
defer os.RemoveAll(dir)
|
|
src := filepath.Join(dir, "probe_arm64.s")
|
|
if err := os.WriteFile(src, []byte("TEXT \u00b7x(SB), $0-0\n\tRET\n"), 0o644); err != nil {
|
|
preambleAARCH64Err = err
|
|
return
|
|
}
|
|
obj := filepath.Join(dir, "probe.o")
|
|
cmd := exec.Command(goBin, "tool", "asm", "-p", "probe", "-o", obj, src)
|
|
cmd.Env = append(os.Environ(), "GOARCH=arm64")
|
|
if out, err := cmd.CombinedOutput(); err != nil {
|
|
preambleAARCH64Err = fmt.Errorf("probing the assembler for the object header: %v\n%s", err, out)
|
|
return
|
|
}
|
|
data, err := os.ReadFile(obj)
|
|
if err != nil {
|
|
preambleAARCH64Err = err
|
|
return
|
|
}
|
|
i := bytes.Index(data, []byte("\n!\n"))
|
|
if i < 0 || !bytes.HasPrefix(data[i+3:], []byte(goobjMagic)) {
|
|
preambleAARCH64Err = fmt.Errorf("unrecognised assembler object layout")
|
|
return
|
|
}
|
|
preambleAARCH64 = data[:i+3]
|
|
})
|
|
return preambleAARCH64, preambleAARCH64Err
|
|
}
|