addr2line on kernel module

by

I suppose the module is built with debug info included. If so, you can use gdb or objdump to find out which source file and line each address belongs to. Something like this:

$ gdb "$(modinfo -n my_module)"
(gdb) list *(some_function+0x12c)

Gdb will now tell the name of the source file and the line in it.

You can also do a similar thing with objdump but it is a bit more difficult. First, disassemble the module:

objdump -dSlr my_module.ko > my_module.disasm

When called with -S option, objdump will include the source lines in the resulting listing where appropriate.

You can now scroll the listing down to the code of some_function, find the instruction at offset 0x12c from the beginning of the function. The source line will be indicated above it.

EDIT:

After many experiments, I found that although addr2line can indeed be used for kernel modules, eu-addr2line (a similar tool from elfutils) seems to be more reliable. That is, sometimes addr2line output incorrect source lines but eu-add2line did things right.

To use eu-addr2line, one may need to install libdw and libebl libraries if they are not already installed along with elfutils.

The usage is similar to that of addr2line:

eu-addr2line -f -e <path_to_the_module> -j <section_name> <offset_in_section>

If the debug information for a kernel module is stored in separate file (this is often the case for the kernels provided by the major Linux distros), the path to that file should be used as <path_to_the_module>.

More Related Contents:

  1. What are vdso and vsyscall?
  2. What are the implications of the linux __user macro?
  3. How to call exported kernel module functions from another module?
  4. Why my kernel log is not showing the latest output?
  5. How to use lockdep feature in linux kernel for deadlock detection
  6. Debugging a linked-list
  7. Is bool a native C type?
  8. How can one grab a stack trace in C?
  9. Linux Kernel: System call hooking example
  10. How to know linux scheduler time slice?
  11. How to use netlink socket to communicate with a kernel module?
  12. How to get function’s name from function’s pointer in Linux kernel?
  13. Unexpected output when printing directly to text video memory
  14. How Can I debug a C program on Linux?
  15. Is it possible to “jump”/”skip” in GDB debugger?
  16. How to access mmaped /dev/mem without crashing the Linux kernel?
  17. Kernel zeroes memory?
  18. How to solve “ptrace operation not permitted” when trying to attach GDB to a process?
  19. Rationale behind the container_of macro in linux/list.h
  20. Cannot insert breakpoints. Addresses with low values
  21. How can I get a filename from a file descriptor inside a kernel module?
  22. What is the difference between a Linux platform driver and normal device driver?
  23. segfault only when NOT using debugger
  24. What does a dot before the variable name in struct mean?
  25. Checking if errno != EINTR: what does it mean?
  26. mmap, msync and linux process termination
  27. How can a C program produce a core dump of itself without terminating?
  28. Why does malloc allocate a different number of bytes than requested?
  29. Efficient way to find task_struct by pid
  30. Where can I find system call source code?

Leave a Comment