适用于Linux内核的线程感知gdb [英] thread-aware gdb for the Linux kernel

问题描述

我正在使用连接到虚拟机串行端口的gdb调试Linux内核。

I am using gdb attached to a serial port of a virtual machine to debug linux kernel.

我想知道，是否有任何补丁/插件可以使gdb理解linux内核的某些数据结构并使它具有线程意识？

I am wondering, if there is any patches/plugins which can make the gdb understand some of linux kernel's data structure and make it "thread aware"?

我的意思是在gdb下，我可以看到那里有多少个内核线程，它们的状态，以及每个线程的堆栈信息。

By that I mean under gdb I can see how many kernel threads are there, their status, and for each thread, their stack information.

推荐答案

libvmi

https://github.com/libvmi/libvmi

该项目可以 LibVMI：简化的虚拟机内省听起来真的很近。

This project does "LibVMI: Simplified Virtual Machine Introspection" which sounds really close.

该项目特别是 https://github.com/Wenzel/pyvmidbg 使用libvmi并提供了一个演示视频，其中调试了Windows用户界面应用程序表单，没有内存冲突。

This project in particular https://github.com/Wenzel/pyvmidbg uses libvmi and features a demo video of debugging a Windows userland application form inside it, without memory conflicts.

截至2019年5月，存在两个限制，但是截至2019年5月，这两个限制应该通过一些工作来克服： https://github.com/Wenzel/pyvmidbg/issues/24

As of May 2019, there are two limitations however as of May 2019, both of which could be overcome with some work: https://github.com/Wenzel/pyvmidbg/issues/24

• Linux内存解析尚未完成


• 需要Xen

该项目的开发人员还通过以下方式进一步回答： https ：//stackoverflow.com/a/56369454/895245

The developer of that project also answered further at: https://stackoverflow.com/a/56369454/895245

用这些库来实现它，将是当今实现此目标的最佳方法。

Implementing it with those libraries would be in my opinion the best way to achieve this goal today.

Linaro lkd-python

Linaro lkd-python

首先，此Linaro页面声称具有有效的设置： https：// wiki。 linaro.org/LandingTeams/ST/GDB ，可让您执行常规的线程操作，例如 thread ， bt 等，但它依赖于GDB分支。稍后再测试。在2016年， https://youtu.be/pqn5hIrz3A8 表示该实现是用C语言编写的，而不是Python脚本不幸的是，这样做会更好并且避免分叉。可以在以下位置找到lkd-python的草图： https://git.linaro.org/people/lee.jones/kieran.bingham/binutils-gdb.git/log/?h=lkd-python

First, this Linaro page claims to have a working setup: https://wiki.linaro.org/LandingTeams/ST/GDB that allows you to do usual thread operations such as thread, bt, etc., but it relies on a GDB fork. I will test it out later. In 2016, https://youtu.be/pqn5hIrz3A8 says that the implementation was in C, not as Python scripts unfortunately, which would be better and avoid forking. The sketch for lkd-python can be found at: https://git.linaro.org/people/lee.jones/kieran.bingham/binutils-gdb.git/log/?h=lkd-python

Linux内核树内GDB脚本+我的大脑

然后我尝试查看可以使用v4.17版本的内核树内Python脚本加上一些手动干预作为原型，但还没有完全实现。

I then tried to see what I could do with the kernel in-tree Python scripts at v4.17 + some manual intervention as a prototype, but didn't quite get there yet.

我已经测试过使用此高度自动化的QEMU + Buildroot设置。

I have tested using this highly automated QEMU + Buildroot setup.

首先按照我在以下步骤中描述的过程进行操作：如何使用GDB和QEMU调试Linux内核？以获取GDB w

First follow the procedure I described at: How to debug the Linux kernel with GDB and QEMU? to get GDB working.

然后，如下所述：如何使用QEMU调试Linux内核模块？使用以下命令运行GDB：

Then, as described at: How to debug Linux kernel modules with QEMU? run GDB with:

gdb -ex add-auto-load-safe-path /full/path/to/linux/kernel

这将从 scripts / gdb 加载树内GDB Python脚本。

This loads the in-tree GDB Python scripts from scripts/gdb.

其中一个脚本提供了：

lx-ps

列出所有格式如下的线程：

which lists all threads with format:

0xffff88000ed08000 1 init
0xffff88000ed08ac0 2 kthreadd

第一个字段是 task_struct 结构的地址，因此我们可以看到整个结构，其中包括：

The first field is the address of the task_struct struct, so we can see the entire struct with:

p ((struct task_struct)*0xffff88000ed08000 

从理论上讲，这应该使我们能够获取我们想要的有关该过程的任何信息。

which should in theory allow us to get any information we want about the process.

现在我想找到PC。对于ARM，我已经看到：在内核中查找进程的程序计数器，然后尝试：

Now I wanted to find the PC. For ARM, I've seen: Find program counter of process in kernel and I tried:

task_pt_regs((struct thread_info *)((struct task_struct)*0xffffffc00e8f8000))->uregs[ARM_pc]

但 task_pt_regs 是 #define ，如果没有 -ggdb3 ，GDB将看不到定义：如何在GDB中打印#defined常量？显然未设置？

but task_pt_regs is a #define and GDB cannot see defines without -ggdb3: How do I print a #defined constant in GDB? which are apparently not set?

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