Adrián Moreno via dev <[email protected]> writes: > On Tue, Jun 10, 2025 at 06:16:38AM -0400, Aaron Conole wrote: >> Adrian Moreno via dev <[email protected]> writes: >> >> > Use the barrier trick to avoid clang from optimizing the 'size' variable >> > that can cause the verifier to think that 'size' can be negative: >> > >> > ./upcall_monitor.py >> > 119: (85) call bpf_probe_read_kernel#113 >> > R2 min value is negative, either use unsigned or 'var &= const' >> > processed 131 insns (limit 1000000) max_states_per_insn 0 total_states >> > peak_states 9 mark_read 3 >> > Traceback (most recent call last): >> > File "/ovs/utilities/usdt-scripts/./upcall_monitor.py", line 729, in >> > odule> >> > main() >> > File "/ovs/utilities/usdt-scripts/./upcall_monitor.py", line 697, in >> > in >> > b = BPF(text=source, usdt_contexts=usdt, debug=options.debug) >> > File "/usr/lib/python3.9/site-packages/bcc/__init__.py", line 373, in >> > init__ >> > self._trace_autoload() >> > File "/usr/lib/python3.9/site-packages/bcc/__init__.py", line 1241, in >> > race_autoload >> > fn = self.load_func(func_name, BPF.KPROBE) >> > File "/usr/lib/python3.9/site-packages/bcc/__init__.py", line 412, in >> > ad_func >> > raise Exception("Failed to load BPF program %s: %s" % >> > Exception: Failed to load BPF program b'kretprobe__ovs_dp_upcall': >> > permission denied. >> > >> > Signed-off-by: Adrian Moreno <[email protected]> >> > --- >> >> Looks fine to me, but I think it would be useful to include which kernel >> version(s) you observed this issue with. For example, was this on >> RHEL9/Centos9? Ubuntu 22.04? Debian? Kernel 4.18, 5.14, latest >> upstream? >> > > Good point, I missed that. > I found this in a RHEL kernel (kernel-5.14.0-427.72.1.el9_4). > > Should I repost and update the commit message?
That would be great. Please include details of the bcc / clang / gcc and python that you used. I do consider this as a kind of fix, so we probably should be backporting it. > I did try to reproduce in latest upstream kernels but bcc is just > completely failing on those. > I Need to look deeper. > > Thanks. > Adrián > > _______________________________________________ > dev mailing list > [email protected] > https://mail.openvswitch.org/mailman/listinfo/ovs-dev _______________________________________________ dev mailing list [email protected] https://mail.openvswitch.org/mailman/listinfo/ovs-dev
