Ubuntu
linux package

XDP eBPF programs fail to verify on Zesty ppc64el

Bug #1699627 reported by Daniel Axtens
6
This bug affects 1 person
Affects Status Importance Assigned to Milestone
linux (Ubuntu)
Fix Released
Undecided
Daniel Axtens
Zesty
Fix Released
Undecided
Unassigned

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.)

See original description
Daniel Axtens (daxtens)
description: updated
Juerg Haefliger (juergh)
Changed in linux (Ubuntu Zesty):
status: New → Fix Committed
Revision history for this message
Daniel Axtens (daxtens) wrote :

Verified in my qemu tcg guest.

tags: added: verification-done-zesty
Revision history for this message
Daniel Axtens (daxtens) wrote :

Also verified by an IBMer on a real P8.

Revision history for this message
Launchpad Janitor (janitor) wrote :
Download full text (8.1 KiB)

This bug was fixed in the package linux - 4.10.0-28.32

---------------
linux (4.10.0-28.32) zesty; urgency=low

  * linux: 4.10.0-28.32 -proposed tracker (LP: #1701013)

  * KILLER1435-S[0489:e0a2] BT cannot search BT 4.0 device (LP: #1699651)
    - Bluetooth: btusb: Add support for 0489:e0a2 QCA_ROME device

  * aacraid driver may return uninitialized stack data to userspace
    (LP: #1700077)
    - SAUCE: scsi: aacraid: Don't copy uninitialized stack memory to userspace

  * CVE-2017-9605
    - drm/vmwgfx: Make sure backup_handle is always valid

  * CVE-2017-1000380
    - ALSA: timer: Fix race between read and ioctl
    - ALSA: timer: Fix missing queue indices reset at SNDRV_TIMER_IOCTL_SELECT

  * XDP eBPF programs fail to verify on Zesty ppc64el (LP: #1699627)
    - [Config] ppc64el: build for Power8 not Power7

  * AACRAID for power9 platform (LP: #1689980)
    - scripts/spelling.txt: add "therfore" pattern and fix typo instances
    - scsi: aacraid: fix PCI error recovery path
    - scsi: aacraid: pci_alloc_consistent() failures on ARM64
    - scsi: aacraid: Remove __GFP_DMA for raw srb memory
    - scsi: aacraid: Fix DMAR issues with iommu=pt
    - scsi: aacraid: Added 32 and 64 queue depth for arc natives
    - scsi: aacraid: Set correct Queue Depth for HBA1000 RAW disks
    - scsi: aacraid: Remove reset support from check_health
    - scsi: aacraid: Change wait time for fib completion
    - scsi: aacraid: Log count info of scsi cmds before reset
    - scsi: aacraid: Print ctrl status before eh reset
    - scsi: aacraid: Using single reset mask for IOP reset
    - scsi: aacraid: Rework IOP reset
    - scsi: aacraid: Add periodic checks to see IOP reset status
    - scsi: aacraid: Rework SOFT reset code
    - scsi: aacraid: Rework aac_src_restart
    - scsi: aacraid: Use correct function to get ctrl health
    - scsi: aacraid: Make sure ioctl returns on controller reset
    - scsi: aacraid: Enable ctrl reset for both hba and arc
    - scsi: aacraid: Add reset debugging statements
    - scsi: aacraid: Remove reference to Series-9
    - scsi: aacraid: Update driver version to 50834

  * arm64 kernel crashdump support (LP: #1694859)
    - memblock: add memblock_clear_nomap()
    - memblock: add memblock_cap_memory_range()
    - arm64: limit memory regions based on DT property, usable-memory-range
    - arm64: kdump: reserve memory for crash dump kernel
    - arm64: mm: add set_memory_valid()
    - arm64: mm: use phys_addr_t instead of unsigned long in __map_memblock
    - arm64: kdump: protect crash dump kernel memory
    - arm64: hibernate: preserve kdump image around hibernation
    - arm64: kdump: implement machine_crash_shutdown()
    - arm64: kdump: add VMCOREINFO's for user-space tools
    - [Config] CONFIG_CRASH_DUMP=y on arm64
    - arm64: kdump: provide /proc/vmcore file
    - Documentation: kdump: describe arm64 port
    - Documentation: dt: chosen properties for arm64 kdump
    - efi/libstub/arm*: Set default address and size cells values for an empty dtb

  * hibmc driver does not include "pci:" prefix in bus ID (LP: #1698700)
    - SAUCE: drm: hibmc: Use set_busid function from drm core

  * Processes in "D" state due to za...

Read more...

Changed in linux (Ubuntu Zesty):
status: Fix Committed → Fix Released
Daniel Axtens (daxtens)
Changed in linux (Ubuntu):
status: In Progress → Fix Released
To post a comment you must log in.
This report contains Public information  
Everyone can see this information.
Subscribing...

Other bug subscribers

Remote bug watches

Bug watches keep track of this bug in other bug trackers.