Added memory address patching
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@ -2,3 +2,6 @@ package asm
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// Address represents a memory address.
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type Address = uint32
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// Index references an instruction by its position.
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type Index = uint32
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@ -1,37 +1,78 @@
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package asm
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import (
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"bytes"
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"encoding/binary"
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"git.akyoto.dev/cli/q/src/asm/x64"
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"git.akyoto.dev/cli/q/src/config"
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"git.akyoto.dev/cli/q/src/log"
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"git.akyoto.dev/cli/q/src/register"
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)
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// Assembler contains a list of instructions.
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type Assembler struct {
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instructions []Instruction
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labels map[string]int
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labels map[string]Index
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verbose bool
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}
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// New creates a new assembler.
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func New() *Assembler {
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return &Assembler{
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instructions: make([]Instruction, 0, 8),
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labels: map[string]int{},
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labels: map[string]Index{},
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verbose: true,
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}
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}
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// Finalize generates the final machine code.
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func (a *Assembler) Finalize() *Result {
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final := Result{}
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result := &Result{}
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pointers := map[Address]Address{}
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code := bytes.NewBuffer(result.Code)
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for _, instr := range a.instructions {
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instr.Write(&final.Code)
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for _, x := range a.instructions {
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if a.verbose {
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log.Info.Println(x.String())
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}
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return &final
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switch x.Mnemonic {
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case MOV:
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x64.MoveRegNum32(code, uint8(x.Destination), uint32(x.Number))
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case MOVDATA:
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position := result.AddData(x.Data)
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x64.MoveRegNum32(code, uint8(x.Destination), 0)
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pointers[Address(code.Len()-4)] = position
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case SYSCALL:
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x64.Syscall(code)
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}
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}
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result.Code = code.Bytes()
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dataStart := config.BaseAddress + config.CodeOffset + Address(len(result.Code))
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for codePos, dataPos := range pointers {
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binary.LittleEndian.PutUint32(result.Code[codePos:codePos+4], dataStart+dataPos)
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}
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return result
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}
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// AddLabel creates a new label at the current position.
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func (a *Assembler) AddLabel(name string) {
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a.labels[name] = len(a.instructions)
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a.labels[name] = Index(len(a.instructions))
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}
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// MoveRegisterData moves a data section address into the given register.
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func (a *Assembler) MoveRegisterData(reg register.ID, data []byte) {
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a.instructions = append(a.instructions, Instruction{
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Mnemonic: MOVDATA,
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Destination: reg,
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Data: data,
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})
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}
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// MoveRegisterNumber moves a number into the given register.
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@ -2,9 +2,7 @@ package asm
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import (
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"fmt"
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"io"
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"git.akyoto.dev/cli/q/src/asm/x64"
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"git.akyoto.dev/cli/q/src/register"
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)
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@ -14,16 +12,7 @@ type Instruction struct {
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Source register.ID
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Destination register.ID
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Number uint64
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}
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// Write writes the machine code of the instruction.
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func (x *Instruction) Write(w io.ByteWriter) {
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switch x.Mnemonic {
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case MOV:
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x64.MoveRegNum32(w, uint8(x.Destination), uint32(x.Number))
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case SYSCALL:
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x64.Syscall(w)
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}
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Data []byte
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}
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// String returns the assembler representation of the instruction.
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@ -31,6 +20,8 @@ func (x *Instruction) String() string {
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switch x.Mnemonic {
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case MOV:
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return fmt.Sprintf("%s %s, %x", x.Mnemonic, x.Destination, x.Number)
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case MOVDATA:
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return fmt.Sprintf("%s %s, %v", x.Mnemonic, x.Destination, x.Data)
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case SYSCALL:
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return x.Mnemonic.String()
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default:
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@ -5,6 +5,7 @@ type Mnemonic uint8
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const (
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NONE Mnemonic = iota
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MOV
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MOVDATA
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SYSCALL
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)
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@ -13,6 +14,9 @@ func (m Mnemonic) String() string {
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case MOV:
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return "mov"
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case MOVDATA:
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return "mov"
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case SYSCALL:
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return "syscall"
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}
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@ -4,6 +4,19 @@ import "bytes"
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// Result is the compilation result and contains the machine code as well as the data.
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type Result struct {
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Code bytes.Buffer
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Data bytes.Buffer
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Code []byte
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Data []byte
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}
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// AddData adds the given bytes to the data block and returns the address relative to the start of the data section.
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func (result *Result) AddData(block []byte) Address {
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position := bytes.Index(result.Data, block)
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if position != -1 {
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return Address(position)
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}
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address := Address(len(result.Data))
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result.Data = append(result.Data, block...)
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return address
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}
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@ -43,8 +43,16 @@ func (build *Build) Run() error {
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a.MoveRegisterNumber(register.Syscall0, syscall.Write)
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a.MoveRegisterNumber(register.Syscall1, 1)
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a.MoveRegisterNumber(register.Syscall2, 0x4000a2)
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a.MoveRegisterNumber(register.Syscall3, 6)
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hello := []byte("Hello\n")
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a.MoveRegisterData(register.Syscall2, hello)
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a.MoveRegisterNumber(register.Syscall3, uint64(len(hello)))
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a.Syscall()
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a.MoveRegisterNumber(register.Syscall0, syscall.Write)
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a.MoveRegisterNumber(register.Syscall1, 1)
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world := []byte("World\n")
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a.MoveRegisterData(register.Syscall2, world)
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a.MoveRegisterNumber(register.Syscall3, uint64(len(world)))
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a.Syscall()
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a.MoveRegisterNumber(register.Syscall0, syscall.Exit)
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@ -52,13 +60,12 @@ func (build *Build) Run() error {
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a.Syscall()
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result := a.Finalize()
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result.Data.WriteString("Hello\n")
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if !build.WriteExecutable {
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return nil
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}
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return writeToDisk(build.Executable(), result.Code.Bytes(), result.Data.Bytes())
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return writeToDisk(build.Executable(), result.Code, result.Data)
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}
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// Compile compiles all the functions.
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8
src/config/config.go
Normal file
8
src/config/config.go
Normal file
@ -0,0 +1,8 @@
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package config
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const (
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MinAddress = 0x10000
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BaseAddress = 0x40 * MinAddress
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CodeOffset = 0x80
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Align = 0x10
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)
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@ -3,11 +3,8 @@ package elf
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import (
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"encoding/binary"
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"io"
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)
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const (
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minAddress = 0x10000
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baseAddress = 0x40 * minAddress
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"git.akyoto.dev/cli/q/src/config"
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)
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// ELF represents an ELF file.
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@ -31,7 +28,7 @@ func New(code []byte, data []byte) *ELF {
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Type: TypeExecutable,
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Architecture: ArchitectureAMD64,
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FileVersion: 1,
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EntryPointInMemory: baseAddress + 0x80,
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EntryPointInMemory: config.BaseAddress + config.CodeOffset,
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ProgramHeaderOffset: HeaderSize,
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SectionHeaderOffset: 0,
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Flags: 0,
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@ -45,12 +42,12 @@ func New(code []byte, data []byte) *ELF {
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ProgramHeader: ProgramHeader{
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Type: ProgramTypeLOAD,
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Flags: ProgramFlagsExecutable,
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Offset: 0x80,
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VirtualAddress: baseAddress + 0x80,
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PhysicalAddress: baseAddress + 0x80,
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Offset: config.CodeOffset,
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VirtualAddress: config.BaseAddress + config.CodeOffset,
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PhysicalAddress: config.BaseAddress + config.CodeOffset,
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SizeInFile: int64(len(code)),
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SizeInMemory: int64(len(code)),
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Align: Align,
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Align: config.Align,
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},
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Code: code,
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Data: data,
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TypeExecutable = 2
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ArchitectureAMD64 = 0x3E
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HeaderSize = 64
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Align = 16
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)
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// Header contains general information.
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