调试在Linux下捕获SIGKILL的程序 [英] Debugging program that catches SIGKILL under Linux

问题描述

我在Linux下编写了一个使用AVX指令的小型C ++程序。但程序收到 SIGKILL 信号并退出。看来原因是某些非法指令或错误的价值传递给了指令。我需要了解它在程序的哪个地方接收到 SIGKILL （最好在什么指令下）。但是，当我在GDB中运行我的程序时，程序在收到 SIGKILL 时无法调试。我尝试设置：

 （gdb）句柄SIGKILL stop print nopass 
  

但是在我调试它之前，程序仍然收到SIGKILL并退出。您有任何提示如何处理这个问题吗？

signal（7）手册页告诉你在非法机器指令（或

 
 
 code> SIGILL 4核心非法指令
  

发送信号。请注意它是 SIGILL not SIGKILL （字母 K





回想一下，并非每个处理器都知道 AVX 。 （在那些不支持AVX的应用程序中，它可能是一个非法的操作码）。输入 cat / proc / cpuinfo （或者 grep avx / proc / cpuinfo ）来知道你的处理器是否接受它。查看 proc（5）

^{所以我猜你的程序得到了 SIGILL （ not SIGKILL ）signal。}

您可以捕获 SIGILL em> 无法捕捉 SIGKILL ）。

我在这个答案（关于 SIGSEGV ）适用于 SIGILL ;用一些非常复杂的机器和系统特定的C代码，你可以捕获 SIGILL ，并确保从信号返回处理程序（安装时使用 SA_SIGINFO 并深入处理 ucontext_t * 第三个参数），执行继续执行非法指令。 / p>

您可以配置 gdb 明智地处理 SIGILL 。阅读GDB文档的信号章节，您可能需要处理SIGILL 和/或 p $ _siginfo 命令。

I have written small C++ program under Linux that uses AVX instructions. But the program receives SIGKILL signal and exits. It seems that the reason is some illegal instruction or wrong value passed to an instruction. I would need to learn at what point of the program it receives SIGKILL (at what instruction at best). But, when I run my program in GDB, program exits at the moment when it receives SIGKILLand cannot be debugged. I tried to set:

    (gdb) handle SIGKILL stop print nopass

but program still receives SIGKILL and exits before I can debug it. Do you have any tip how to work with this?

解决方案

The signal(7) man page tells that on illegal machine instruction (or illegal opcode), the

   SIGILL        4       Core    Illegal Instruction

signal is sent. Notice that it is SIGILL not SIGKILL (the letter K makes a big difference).

Recall that not every processor know about AVX. (On those that don't support AVX, it probably is an illegal opcode). Type cat /proc/cpuinfo (or grep avx /proc/cpuinfo) to know if your's processor accepts it. See proc(5)

^{So I guess that your program is getting the SIGILL (not SIGKILL) signal.}

You can catch SIGILL (but you cannot catch SIGKILL).

What I explained in this answer (about SIGSEGV) is applicable to SIGILL; with some very tricky machine and system specific C code, you might catch SIGILL and ensure that upon return from the signal handler (installed with SA_SIGINFO and deeply processing the ucontext_t* third argument) the execution continues outside of the illegal instructions.

And you could configure gdb to handle SIGILL wisely. Read the signals chapter of GDB documentation, you probably want the handle SIGILL and/or p $_siginfo command.

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