System Practice Learning ARMv8 Assembly – Outline

Let’s set a learning plan for ARMv8 assembly language. After learning, aim to master ARMv8 assembly knowledge and be able to write some simple assembly code.

Phase 1: Basic Preparation (1-2 weeks)

Goals:

1. Understand computer architecture and core concepts of the ARMv8 architecture.

2. Set up the development environment.

3. Write the first assembly program.

Learning Content:

1. Basics of Computer Organization:

• The relationship between CPU, registers, memory, and instruction set.

• Basics of binary/hexadecimal (commonly used in ARM assembly).

• Harvard architecture vs Von Neumann architecture.

• Differences between AArch64 (64-bit) and AArch32 (32-bit) modes.

• Register set: 31 general-purpose registers (X0-X30), SP (stack pointer), PC (program counter).

• Instruction format: fixed length (4 bytes), condition execution flags (NZCV).

• Cross-compiler:<span>aarch64-linux-gnu-gcc</span> (Linux) or ARM Toolchain (Windows/Mac).

• Simulator: QEMU (to run ARM programs).

• Debugging tools: GDB + <span>gdb-multiarch</span>.

• Text editor: VS Code/VIM + ARM assembly syntax plugin.

// hello.s
.text
.global _start
_start:
    mov x0, #1      // stdout
    ldr x1, =msg
    ldr x2, =len
    mov x8, #64     // sys_write system call number
    svc #0          // trigger system call
    mov x0, #0      // exit status code
    mov x8, #93     // sys_exit system call number
    svc #0
.data
msg: .ascii "Hello, ARMv8!\n"
len = . - msg

• Compile:<span>aarch64-linux-gnu-as hello.s -o hello.o && aarch64-linux-gnu-ld hello.o -o hello</span>

• Run:<span>qemu-aarch64 ./hello</span>

Phase 2: Core Instructions and Programming (3-4 weeks)

Goals:

1. Master commonly used instruction sets in ARMv8.

2. Understand memory operations and function calls.

Learning Content:

1. Registers and Instruction Format:

• General-purpose registers (X0-X30), SP, PC, status register (NZCV).

• Instruction syntax:<span>opcode destination_register, source_operand1, source_operand2</span> (e.g., <span>ADD X0, X1, X2</span>).

• Data Processing:<span>MOV</span>, <span>ADD</span>, <span>SUB</span>, <span>MUL</span>, <span>AND</span>, <span>ORR</span>, <span>EOR</span>.

• Memory Operations:<span>LDR</span> (load), <span>STR</span> (store), <span>LDP</span>/<span>STP</span> (multiple register operations).

• Control Flow:<span>B</span> (branch), <span>BL</span> (branch with link), <span>RET</span> (return), <span>CBNZ</span> (conditional branch if not zero).

• Immediate addressing:<span>MOV X0, #0x1234</span>

• Register indirect addressing:<span>LDR X1, [X2]</span>

• Base + offset addressing:<span>STR X3, [X4, #8]</span>

• Pre/post-indexed addressing:<span>LDR X5, [X6], #4</span>

• Calling convention: parameters are passed via X0-X7, return value in X0.

• Save registers:<span>STP X29, X30, [SP, #-16]!</span> (save frame pointer and return address).

• Stack operation example:

  .global my_function
  my_function:
      stp x29, x30, [sp, #-16]!  // Save frame pointer and return address
      mov x29, sp                // Set new frame pointer
      // Function body
      ldp x29, x30, [sp], #16    // Restore frame pointer and return address
      ret

• Implement Fibonacci sequence calculation.

• Write a memory copy function (similar to <span>memcpy</span>).

• Conditional check: determine if a number is prime.

Phase 3: Advanced Topics (5-6 weeks)

Goals:

1. Master SIMD, exception handling, and system programming.

2. Optimize assembly code performance.

Learning Content:

1. SIMD and NEON Instructions:

• Vector registers (V0-V31), supporting 128-bit operations.

• Single Instruction Multiple Data (SIMD) instruction example:

  // Add 4 32-bit integers
  ADD V0.4S, V1.4S, V2.4S

• Exception levels (EL0-EL3).

• Exception Vector Table.

• Write a simple interrupt handler.

• System calls (via <span>svc</span> instruction).

• Write code that interacts directly with hardware (e.g., manipulating GPIO).

• Loop Unrolling.

• Instruction reordering to avoid pipeline stalls.

• Use Performance Monitoring Counters (PMC) to analyze bottlenecks.

• Embed assembly in C code:

  void add(int a, int b) {
      asm volatile (
          "ADD %0, %1, %2"
          : "=r"(a)
          : "r"(a), "r"(b)
      );
  }

• Optimize matrix multiplication (NEON acceleration).

• Implement a simple operating system kernel module.

• Write shellcode and test its reliability.

Phase 4: Practical Application and Expansion (Ongoing)

Recommended Directions:

1. Reverse Engineering: Use IDA Pro/Ghidra to analyze ARM binaries.

2. Embedded Development: Run bare-metal programs on Raspberry Pi or STM32 boards.

3. Security Research: Exploit vulnerabilities in ARM architecture (e.g., ROP chain construction).

Learning Resources:

1. Books:

• “ARMv8-A Architecture Reference Manual” (official documentation).

• “Assembly Language: Based on ARMv8 Architecture” (domestic textbook).

• “Programming with 64-Bit ARM Assembly Language” (practical-oriented).

• ARM official training (https://developer.arm.com).

• Coursera: Embedded Systems Essentials with Arm.

• ARM Developer Forums.

• Stack Overflow’s <span>assembly</span> and <span>arm</span> tags.