如何从Linux内核中的函数指针获取函数名称? [英] How to get function's name from function's pointer in Linux kernel?

问题描述

如何从C语言中的函数的指针中获取函数的名称?

How to get function's name from function's pointer in C?

实际情况是:我正在编写一个Linux内核模块，并且正在调用内核函数.其中一些函数是指针，我想在内核源代码中检查该函数的代码.但是我不知道它指向的是哪个功能.我认为可以这样做是因为，当系统发生故障(内核崩溃)时，它将在屏幕上打印出具有函数名称的当前调用堆栈.但是，我想我错了……是吗?

The real case is: I'm writing a linux kernel module and I'm calling kernel functions. Some of these functions are pointers and I want to inspect the code of that function in the kernel source. But I don't know which function it is pointing to. I thought it could be done because, when the system fails (kernel panic) it prints out in the screen the current callstack with function's names. But, I guess I was wrong... am I?

推荐答案

没有其他帮助，这是不可能直接实现的.

That's not directly possible without additional assistance.

您可以:

1. 在程序映射函数中维护指向名称的指针的表

1. maintain a table in your program mapping function pointers to names

检查可执行文件的符号表(如果有的话).

examine the executable's symbol table, if it has one.

但是，后者是很难的，并且不是可移植的.该方法将取决于操作系统的二进制格式(ELF，a.out，.exe等)，还取决于链接器完成的任何重定位.

The latter, however, is hard, and is not portable. The method will depend on the operating system's binary format (ELF, a.out, .exe, etc), and also on any relocation done by the linker.

由于您现在已经解释了实际的用例，因此答案实际上并不难.内核符号表在/proc/kallsyms中可用，并且有一个用于访问它的API:

Since you've now explained what your real use case is, the answer is actually not that hard. The kernel symbol table is available in /proc/kallsyms, and there's an API for accessing it:

#include <linux/kallsyms.h>

const char *kallsyms_lookup(unsigned long addr, unsigned long *symbolsize,
                            unsigned long *ofset, char **modname, char *namebuf)

void print_symbol(const char *fmt, unsigned long addr)

出于简单调试的目的，后者可能会完全满足您的需要-它获取地址，对其进行格式设置并将其发送给printk，或者您可以将printk与%pF格式说明符一起使用.

For simple debug purposes the latter will probably do exactly what you need - it takes the address, formats it, and sends it to printk, or you can use printk with the %pF format specifier.

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