On Fri, May 24, 2019 at 1:27 AM Josh Poimboeuf <jpoimboe@xxxxxxxxxx> wrote: > > On Fri, May 24, 2019 at 12:41:59AM +0800, Kairui Song wrote: > > On Thu, May 23, 2019 at 11:24 PM Josh Poimboeuf <jpoimboe@xxxxxxxxxx> wrote: > > > > > > On Thu, May 23, 2019 at 10:50:24PM +0800, Kairui Song wrote: > > > > > > Hi Josh, this still won't fix the problem. > > > > > > > > > > > > Problem is not (or not only) with ___bpf_prog_run, what actually went > > > > > > wrong is with the JITed bpf code. > > > > > > > > > > There seem to be a bunch of issues. My patch at least fixes the failing > > > > > selftest reported by Alexei for ORC. > > > > > > > > > > How can I recreate your issue? > > > > > > > > Hmm, I used bcc's example to attach bpf to trace point, and with that > > > > fix stack trace is still invalid. > > > > > > > > CMD I used with bcc: > > > > python3 ./tools/stackcount.py t:sched:sched_fork > > > > > > I've had problems in the past getting bcc to build, so I was hoping it > > > was reproducible with a standalone selftest. > > > > > > > And I just had another try applying your patch, self test is also failing. > > > > > > Is it the same selftest reported by Alexei? > > > > > > test_stacktrace_map:FAIL:compare_map_keys stackid_hmap vs. stackmap err -1 errno 2 > > > > > > > I'm applying on my local master branch, a few days older than > > > > upstream, I can update and try again, am I missing anything? > > > > > > The above patch had some issues, so with some configs you might see an > > > objtool warning for ___bpf_prog_run(), in which case the patch doesn't > > > fix the test_stacktrace_map selftest. > > > > > > Here's the latest version which should fix it in all cases (based on > > > tip/master): > > > > > > https://git.kernel.org/pub/scm/linux/kernel/git/jpoimboe/linux.git/commit/?h=bpf-orc-fix > > > > Hmm, I still get the failure: > > test_stacktrace_map:FAIL:compare_map_keys stackid_hmap vs. stackmap > > err -1 errno 2 > > > > And I didn't see how this will fix the issue. As long as ORC need to > > unwind through the JITed code it will fail. And that will happen > > before reaching ___bpf_prog_run. > > Ok, I was able to recreate by doing > > echo 1 > /proc/sys/net/core/bpf_jit_enable > > first. I'm guessing you have CONFIG_BPF_JIT_ALWAYS_ON. > Yes, with JIT off it will be fixed. I can confirm that. -- Best Regards, Kairui Song
