Question

CPU 内置，以名称访问，速度最快的存储器。包括通用寄存器、控制寄存器和段寄存器。

• 通用寄存器：RAX, RBX, RCX, RDX, RBP, RSP, RSI, RDI, R8-R15
• 指令寄存器：RIP（PC）
• 段寄存器：CS, DS, SS, ES, FS, GS
• 标志寄存器：EFLAGS (OF/DF/IF ...)

RIP 指向下一条要执行的指令地址。RSP 指向栈顶，从高向低扩展。

  64           32     16   8    0
  +======================+==========+======+======+
  |            |      |  AH  |  AL  |
  +======================+==========+======+======+
  |            |      |       |
  |            |      +----- AX ----+
  |            +----- EAX --------------+
  +----- RAX -------------------------------------+
  

REPL

Rappel is a pretty janky assembly REPL. It works by creating a shell ELF, starting it under ptrace, then continiously rewriting/running the .text section, while showing the register states. It's maybe half done right now, and supports Linux x86, amd64, armv7 (no thumb), and armv8 at the moment.

$ apt install -y libedit-dev
$ git clone https://github.com/yrp604/rappel

$ cd rappel
$ make