Linux Kernel Module Cheat

Useless, but a good way to show how hardcore you are. Disable lx-symbols with:

./run-gdb --no-lxsymbols

From inside guest:

insmod timer.ko
cat /proc/modules

as mentioned at:

This will give a line of form:

fops 2327 0 - Live 0xfffffffa00000000

And then tell GDB where the module was loaded with:

Ctrl-C
add-symbol-file ../../../rootfs_overlay/x86_64/timer.ko 0xffffffffc0000000
0xffffffffc0000000

Alternatively, if the module panics before you can read /proc/modules, there is a pr_debug which shows the load address:

echo 8 > /proc/sys/kernel/printk
echo 'file kernel/module.c +p' > /sys/kernel/debug/dynamic_debug/control
./linux/myinsmod.out hello.ko

And then search for a line of type:

[   84.877482]  0xfffffffa00000000 .text

Tested on 4f4749148273c282e80b58c59db1b47049e190bf + 1.