Hi Kristen, On Wed, 23 Sep 2020, Kristen Carlson Accardi wrote: > Function Granular Kernel Address Space Layout Randomization (fgkaslr) > --------------------------------------------------------------------- > > This patch set is an implementation of finer grained kernel address space > randomization. It rearranges your kernel code at load time > on a per-function level granularity, with only around a second added to > boot time. I ran live patching kernel selftests on the patch set and everything passed fine. However, we also use not-yet-upstream set of tests at SUSE for testing live patching [1] and one of them, klp_tc_12.sh, is failing. You should be able to run the set on upstream as is. The test uninterruptedly sleeps in a kretprobed function called by a patched one. The current master without fgkaslr patch set reports the stack of the sleeping task as unreliable and live patching fails. The situation is different with fgkaslr (even with nofgkaslr on the command line). The stack is returned as reliable. It looks something like [<0>] __schedule+0x465/0xa40 [<0>] schedule+0x55/0xd0 [<0>] orig_do_sleep+0xb1/0x110 [klp_test_support_mod] [<0>] swap_pages+0x7f/0x7f where the last entry is not reliable. I've seen kretprobe_trampoline+0x0/0x4a and some other symbols there too. Since the patched function (orig_sleep_uninterruptible_set) is not on the stack, live patching succeeds, which is not intended. With kprobe setting removed, all works as expected. So I wonder if there is still some issue with ORC somewhere as you mentioned in v4 thread. I'll investigate more next week, but wanted to report early. Regards Miroslav [1] https://github.com/lpechacek/qa_test_klp
