** Description changed: SRU Justification [Impact] Some XDP examples such as https://github.com/netoptimizer/prototype-kernel fail on ppc64el at the eBPF verification stage. [Fix] This is because CONFIG_HAS_EFFICIENT_UNALIGNED_ACCESS is not set on ppc64el. It is not set because the kernel is being compiled for CPU_POWER7 instead of CPU_POWER8, and we don't have efficient unaligned access on POWER7. Swap to building for POWER8. As a bonus, this should make everything a little bit faster. [Regression Potential] - - IBM never released any officially supported Power7 LE systems - LE + - IBM never released any officially supported Power7 LE systems - LE was only ever supported on Power8. Therefore this should not break any systems. - - Regression potential is also limited to one arch. + - Regression potential is also limited to one arch. - - Artful-next already has this fix and nothing bad has happened there. + - Artful-next already has this fix and nothing bad has happened there. [Test] - On a P8 VM with a virtio network card and 2 vcpus: + Create a P8 VM with a virtio network card and 2 vcpus. + + The VM needs to have some network features turned off, and enough + queues. The following virsh snippet in the <interface> section should + suffice: + + <driver name='vhost' queues='4'> + <host tso4='off' tso6='off' ecn='off' ufo='off'/> + <guest tso4='off' tso6='off' ecn='off' ufo='off'/> + </driver> + + Then: + - apt install clang llvm - get the prototype-kernel repo - - go to the kernel/samples/bpf directory- + - go to the kernel/samples/bpf directory - make - sudo mount -t bpf bpf /sys/fs/bpf/ - sudo ./xdp_ddos01_blacklist --dev enp0s1 Observe that without this patch, we get a long debug splat ending with: 32: (61) r1 = *(u32 *)(r8 +12) misaligned packet access off 0+18+12 size 4 load_bpf_file: Permission denied With this patch we don't get that error and the program is successfully verifies and loads. (It still doesn't run - there is other breakage I'm chasing down - but it definitely gets further.)
-- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1699627 Title: XDP eBPF programs fail to verify on Zesty ppc64el Status in linux package in Ubuntu: In Progress Bug description: SRU Justification [Impact] Some XDP examples such as https://github.com/netoptimizer/prototype-kernel fail on ppc64el at the eBPF verification stage. [Fix] This is because CONFIG_HAS_EFFICIENT_UNALIGNED_ACCESS is not set on ppc64el. It is not set because the kernel is being compiled for CPU_POWER7 instead of CPU_POWER8, and we don't have efficient unaligned access on POWER7. Swap to building for POWER8. As a bonus, this should make everything a little bit faster. [Regression Potential] - IBM never released any officially supported Power7 LE systems - LE was only ever supported on Power8. Therefore this should not break any systems. - Regression potential is also limited to one arch. - Artful-next already has this fix and nothing bad has happened there. [Test] Create a P8 VM with a virtio network card and 2 vcpus. The VM needs to have some network features turned off, and enough queues. The following virsh snippet in the <interface> section should suffice: <driver name='vhost' queues='4'> <host tso4='off' tso6='off' ecn='off' ufo='off'/> <guest tso4='off' tso6='off' ecn='off' ufo='off'/> </driver> Then: - apt install clang llvm - get the prototype-kernel repo - go to the kernel/samples/bpf directory - make - sudo mount -t bpf bpf /sys/fs/bpf/ - sudo ./xdp_ddos01_blacklist --dev enp0s1 Observe that without this patch, we get a long debug splat ending with: 32: (61) r1 = *(u32 *)(r8 +12) misaligned packet access off 0+18+12 size 4 load_bpf_file: Permission denied With this patch we don't get that error and the program is successfully verifies and loads. (It still doesn't run - there is other breakage I'm chasing down - but it definitely gets further.) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1699627/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
