Public bug reported: 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] On a P8 VM with a virtio network card and 2 vcpus: - 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.) ** Affects: linux (Ubuntu) Importance: Undecided Assignee: Daniel Axtens (daxtens) Status: In Progress -- 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] On a P8 VM with a virtio network card and 2 vcpus: - 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
