How to get function’s name from function’s pointer in Linux kernel?

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I’m surprised why everybody says it is not possible. It is possible on Linux for non-static functions.

I know at least two ways to achieve this.

There are GNU functions for backtrace printing: backtrace() and backtrace_symbols() (See man). In your case you don’t need backtrace() as you already have function pointer, you just pass it to backtrace_symbols().

Example (working code):

#include <stdio.h>
#include <execinfo.h>

void foo(void) {
    printf("foo\n");
}

int main(int argc, char *argv[]) {
    void    *funptr = &foo;

    backtrace_symbols_fd(&funptr, 1, 1);

    return 0;
}

Compile with gcc test.c -rdynamic

Output: ./a.out(foo+0x0)[0x8048634]

It gives you binary name, function name, pointer offset from function start and pointer value so you can parse it.

Another way is to use dladdr() (another extension), I guess print_backtrace() uses dladdr(). dladdr() returns Dl_info structure that has function name in dli_sname field. I don’t provide code example here but it is obvious – see man dladdr for details.

NB! Both approaches require function to be non-static!

Well, there is one more way – use debug information using libdwarf but it would require unstripped binary and not very easy to do so I don’t recommend it.

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