On 2/21/24 07:44, Nicolai Stange wrote:

Shresth Prasad shresthprasad7@gmail.com writes:

...

I checked the source code and yes I am on the latest Linux next repo.

Here's the warning: /home/shresthp/dev/linux_work/linux_next/tools/testing/selftests/livepatch/test_modules/test_klp_state.c:38:24: warning: assignment to ‘struct klp_state *’ from ‘int’ makes pointer from integer without a cast [-Wint-conversion]    38 |         loglevel_state = klp_get_state(&patch, CONSOLE_LOGLEVEL_STATE);       |                        ^

Is the declaration of klp_get_state() visible at that point, i.e. is there perhaps any warning about missing declarations above that?

Otherwise C rules would default to assume an 'int' return type.

This is an interesting clue. I thought I might be able to reproduce the build error by modifying include/livepatch.h and running `make -j15 -C tools/testing/selftests/livepatch` ... but that seemed to work fine on my system. I even removed the entire include/ subdir from my tree and it still built the test module. Huh?

Then I moved /lib/modules/$(uname -r)/build out of the way and saw that the compilation failed. Ah hah -- that's right, it's using the system build tree. That version of livepatch.h may have a missing or completely different definition of klp_get_state().

How does this sequence work for you, Shresth:

# Verify that kernel livepatching is turned on $ grep LIVEPATCH .config CONFIG_HAVE_LIVEPATCH=y CONFIG_LIVEPATCH=y

# Build linux-next kernel tree and then the livepatch selftests, # pointing KDIR to this tree $ make -j$(nproc) vmlinux && \ make -j$(nproc) KDIR=$(pwd) -C tools/testing/selftests/livepatch