用VS代码调试NASM [英] Debugging NASM in VS code

问题描述

我有一个简单的C ++程序，该程序调用了一些NASM代码:

main.cpp:

#include <iostream>

extern "C" int foo();

int main() {
  std::cout << "The result is: " << foo() << std::endl;
  return 0;
}

foo.asm:

bits 64
global foo

section .text
foo:
    mov rax, 123
    inc rax
    ret

我可以使用CMake编译所有内容

cmake_minimum_required (VERSION 3.15)

project (assembly-x64 LANGUAGES CXX ASM_NASM)
  
# old school CMAKE to handle NASM formats
if(WIN32)
    set(CMAKE_ASM_NASM_FLAGS_DEBUG "-g -F cv8")
    set(CMAKE_ASM_NASM_OBJECT_FORMAT win64)
elseif(APPLE)
    set(CMAKE_ASM_NASM_FLAGS_DEBUG "-g -F dwarf")
    set(CMAKE_ASM_NASM_OBJECT_FORMAT macho64)
else()
    set(CMAKE_ASM_NASM_FLAGS_DEBUG "-g -F dwarf")
    set(CMAKE_ASM_NASM_OBJECT_FORMAT elf64)
endif()

add_executable(assembly-x64)

target_compile_features(assembly-x64 PUBLIC cxx_std_17)

target_sources(assembly-x64 PRIVATE main.cpp foo.asm)

我得到正确的结果.但是，我希望能够像C ++代码一样调试汇编代码.我可以在foo函数上创建一个断点(虽然不使用GUI)，但是在暂停时它不会显示相应的源位置.有没有办法解决这个问题?我希望能够监视寄存器等.不确定在VS代码中是否可行.

解决方案

简短答案:否.在linux上，从vs-code启动gdb调试asm代码导致快速崩溃.它甚至不允许您在asm代码上放置断点.

阅读更长的答案，以备不时之需.

---

我假设您没有使用Linux，因为我无法使用您提供的cmake在Linux上构建项目.我必须添加以下内容:

...
else()
    set(CMAKE_ASM_NASM_FLAGS_DEBUG "-g -F dwarf")
    set(CMAKE_ASM_NASM_OBJECT_FORMAT elf64)
    # had to add this to build on linux
    set(CMAKE_ASM_NASM_COMPILE_OBJECT "<CMAKE_ASM_NASM_COMPILER> <INCLUDES> \
    <FLAGS> -f ${CMAKE_ASM_NASM_OBJECT_FORMAT} -o <OBJECT> <SOURCE>")
endif()
...

好，所以现在该项目已构建并正在运行.但是，坏消息是我无法设置调试"代理程序. VS-Code的环境. VS-Code最初并没有很好的汇编支持，因此我对此并不感到惊讶.我尝试多次配置launch.json，但是每次启动GDB时，VS-Code崩溃.在Windows或Mac上可能会或可能不会发生这种情况，因此我无法针对这些平台进行回答，但我认为在该平台上将无法使用.

我个人只是直接在终端上使用gdb，因为一旦您弄清了它，它就会更强大且更易于使用.我将为您提供两个工作流程，您可以使用它们代替Vs代码.

使用终端

• 构建可执行文件
• 接下来使用gdb如下启动它:

gdb ./assembly-64 --tui

这将打开gdb并带您进入推针屏幕.

• 让我们假设对于这种类型，我们想在foo处设置一个断点:

b foo

• 现在我们的断点都已设置.我们准备开始调试会话.类型:

run

• 它将在foo处断裂.

但是请稍等，没有寄存器，我们应该如何查看它们?这是我最喜欢的关于gdb的部分.类型:

layout regs

您将在顶部获得一个漂亮的外观窗口，向您显示所有寄存器.甚至会在寄存器更改时突出显示它们，从而使您可以轻松监视更改.

• 除此之外，使用n下一步，使用si进入.基本来说就足够了.如果要在某个存储器位置或寄存器中查看该值.类型:

print $rax

还有很多其他功能，但这将使您快速入门.

GUI

当我发现QtCreator可以很好地调试asm + cpp文件时，我感到非常惊喜.只需加载您的cmake项目并放置断点即可.您可以从Menu->Window->Views->Registers启用寄存器窗格.截图:

还有其他GUI(用于gdb)，nemiver，ddd等.

I have a simple C++ program that calls some NASM code:

main.cpp:

#include <iostream>

extern "C" int foo();

int main() {
  std::cout << "The result is: " << foo() << std::endl;
  return 0;
}

foo.asm:

bits 64
global foo

section .text
foo:
    mov rax, 123
    inc rax
    ret

I can compile everything with CMake

cmake_minimum_required (VERSION 3.15)

project (assembly-x64 LANGUAGES CXX ASM_NASM)
  
# old school CMAKE to handle NASM formats
if(WIN32)
    set(CMAKE_ASM_NASM_FLAGS_DEBUG "-g -F cv8")
    set(CMAKE_ASM_NASM_OBJECT_FORMAT win64)
elseif(APPLE)
    set(CMAKE_ASM_NASM_FLAGS_DEBUG "-g -F dwarf")
    set(CMAKE_ASM_NASM_OBJECT_FORMAT macho64)
else()
    set(CMAKE_ASM_NASM_FLAGS_DEBUG "-g -F dwarf")
    set(CMAKE_ASM_NASM_OBJECT_FORMAT elf64)
endif()

add_executable(assembly-x64)

target_compile_features(assembly-x64 PUBLIC cxx_std_17)

target_sources(assembly-x64 PRIVATE main.cpp foo.asm)

and I get the correct result. However, I'd like to be able to debug the assembly code just like I would the C++ code. I can create a breakpoint on the foo function (not using the GUI though), but it doesn't show me the corresponding source location when it pauses. Is there a way around that issue? I'd like to be able to watch registers, etc. Not sure if it's possible in VS code.

解决方案

Short Answer: No. On linux, launching gdb from vs-code to debug asm code resulted in a quick crash. It doesn't even let you put breakpoints on asm code.

Read the longer answer in case you want to know about the alternatives.

---

I assume you are not using Linux, because I was unable to build the project on Linux with the cmake you provided. I had to add the following:

...
else()
    set(CMAKE_ASM_NASM_FLAGS_DEBUG "-g -F dwarf")
    set(CMAKE_ASM_NASM_OBJECT_FORMAT elf64)
    # had to add this to build on linux
    set(CMAKE_ASM_NASM_COMPILE_OBJECT "<CMAKE_ASM_NASM_COMPILER> <INCLUDES> \
    <FLAGS> -f ${CMAKE_ASM_NASM_OBJECT_FORMAT} -o <OBJECT> <SOURCE>")
endif()
...

Ok, so now the project is built and running. However, the bad news is that I was unable to set up "debugging" environment with VS-Code. VS-Code doesn't really have good assembly support to begin with so I am not really surprised here. I tried to configure launch.json multiple times, but everytime I launch GDB, VS-Code crashes. This may or may not happen on Windows or Mac, so I can not answer for those platforms but I assume it will not work there.

I personally just use gdb from terminal directly because it is more powerful and easy to use once you figure it out. I will give you two work flows which you can use instead of Vs-code.

Use terminal

• Build your executable
• Next launch it using gdb like this:

gdb ./assembly-64 --tui

This will open gdb and bring you to the tui screen.

• Lets assume we want to put a break point at foo, for this type:

b foo

• Now our breakpoints are all set. We are ready to start our debugging session. Type:

run

• It will go and break at foo.

But wait a minute, there are no registers, how should we see them? This is my favourite part about gdb. Type:

layout regs

And you will get a beautiful look window at top showing you all the registers. It will even highlight the registers as they change making it easy for you to monitor changes.

• Other than this, Use n to step next, use si to step into. That's pretty much it for the basics. If you want to see the value at some memory location, or a register. Type:

print $rax

There's a lot more to this, but this will give you a quick start.

GUI

I was pleasantly surprised when I discovered that QtCreator can debug asm + cpp files very nicely. Just load up your cmake project and place your breakpoints. You can enable registers pane from Menu->Window->Views->Registers. Screenshot:

There are other guis(for gdb) out there, nemiver, ddd etc.

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