[Bug 1695093] Re: arm64: "unsupported RELA relocation: 275" loading certain modules

Thu Sep 14 22:22:50 UTC 2017

gcc-5/xenial verified:

ubuntu at neander:~$ cat /proc/version
Linux version 4.4.0-96-generic (buildd at bos01-arm64-013) (gcc version 5.4.0 20160609 (Ubuntu/Linaro 5.4.0-6ubuntu1~16.04.4) ) #119-Ubuntu SMP Tue Sep 12 15:00:28 UTC 2017
ubuntu at neander:~$ sudo dmesg -c > /dev/null
ubuntu at neander:~$ sudo modprobe scsi_debug
modprobe: ERROR: could not insert 'scsi_debug': Exec format error
ubuntu at neander:~$ dmesg
[   65.658638] module scsi_debug: unsupported RELA relocation: 275
ubuntu at neander:~$ sudo dpkg -i linux-image-4.4.0-96-generic_4.4.0-96.119+gccsru.1_arm64.deb && sudo reboot
(Reading database ... 112555 files and directories currently installed.)
Preparing to unpack linux-image-4.4.0-96-generic_4.4.0-96.119+gccsru.1_arm64.deb ...
Done.
Unpacking linux-image-4.4.0-96-generic (4.4.0-96.119+gccsru.1) over (4.4.0-96.119) ...
Examining /etc/kernel/postrm.d .
run-parts: executing /etc/kernel/postrm.d/initramfs-tools 4.4.0-96-generic /boot/vmlinuz-4.4.0-96-generic
run-parts: executing /etc/kernel/postrm.d/zz-flash-kernel 4.4.0-96-generic /boot/vmlinuz-4.4.0-96-generic
run-parts: executing /etc/kernel/postrm.d/zz-update-grub 4.4.0-96-generic /boot/vmlinuz-4.4.0-96-generic
Setting up linux-image-4.4.0-96-generic (4.4.0-96.119+gccsru.1) ...
Running depmod.
update-initramfs: deferring update (hook will be called later)
Not updating initrd symbolic links since we are being updated/reinstalled 
(4.4.0-96.119 was configured last, according to dpkg)
Not updating image symbolic links since we are being updated/reinstalled 
(4.4.0-96.119 was configured last, according to dpkg)
Examining /etc/kernel/postinst.d.
run-parts: executing /etc/kernel/postinst.d/apt-auto-removal 4.4.0-96-generic /boot/vmlinuz-4.4.0-96-generic
run-parts: executing /etc/kernel/postinst.d/initramfs-tools 4.4.0-96-generic /boot/vmlinuz-4.4.0-96-generic
update-initramfs: Generating /boot/initrd.img-4.4.0-96-generic
W: Possible missing firmware /lib/firmware/ast_dp501_fw.bin for module ast
W: mdadm: /etc/mdadm/mdadm.conf defines no arrays.
flash-kernel: deferring update (trigger activated)
run-parts: executing /etc/kernel/postinst.d/unattended-upgrades 4.4.0-96-generic /boot/vmlinuz-4.4.0-96-generic
run-parts: executing /etc/kernel/postinst.d/update-notifier 4.4.0-96-generic /boot/vmlinuz-4.4.0-96-generic
run-parts: executing /etc/kernel/postinst.d/zz-flash-kernel 4.4.0-96-generic /boot/vmlinuz-4.4.0-96-generic
flash-kernel: deferring update (trigger activated)
run-parts: executing /etc/kernel/postinst.d/zz-update-grub 4.4.0-96-generic /boot/vmlinuz-4.4.0-96-generic
Generating grub configuration file ...
Warning: Setting GRUB_TIMEOUT to a non-zero value when GRUB_HIDDEN_TIMEOUT is set is no longer supported.
Found linux image: /boot/vmlinuz-4.4.0-96-generic
Found initrd image: /boot/initrd.img-4.4.0-96-generic
Found linux image: /boot/vmlinuz-4.4.0-93-generic
Found initrd image: /boot/initrd.img-4.4.0-93-generic
Adding boot menu entry for EFI firmware configuration
done
Processing triggers for flash-kernel (3.0~rc.4ubuntu62.2) ...
Unsupported platform on EFI system, doing nothing.
Shared connection to 10.229.65.157 closed.

@@@ REBOOT @@@

ubuntu at neander:~$ cat /proc/version
Linux version 4.4.0-96-generic (root at neander) (gcc version 5.4.0 20160609 (Ubuntu/Linaro 5.4.0-6ubuntu1~16.04.5) ) #119+gccsru.1 SMP Thu Sep 14 21:43:33 UTC 2017
ubuntu at neander:~$ sudo modprobe scsi_debug
ubuntu at neander:~$ sudo modprobe -r scsi_debug
ubuntu at neander:~$ sudo dmesg -c > /dev/null
(failed reverse-i-search)`modpor': sudo ^Cdprobe -r scsi_debug
ubuntu at neander:~$ sudo modprobe scsi_debug
ubuntu at neander:~$ dmesg
[   71.235619] scsi_debug:sdebug_driver_probe: host protection
[   71.235628] scsi host5: scsi_debug, version 1.85 [20141022], dev_size_mb=8, opts=0x0
[   71.236469] scsi 5:0:0:0: Direct-Access     Linux    scsi_debug       0184 PQ: 0 ANSI: 6
[   71.237326] sd 5:0:0:0: Attached scsi generic sg3 type 0
[   71.243989] sd 5:0:0:0: [sdd] 16384 512-byte logical blocks: (8.39 MB/8.00 MiB)
[   71.248044] sd 5:0:0:0: [sdd] Write Protect is off
[   71.248051] sd 5:0:0:0: [sdd] Mode Sense: 73 00 10 08
[   71.255975] sd 5:0:0:0: [sdd] Write cache: enabled, read cache: enabled, supports DPO and FUA
[   71.343980] sd 5:0:0:0: [sdd] Attached SCSI disk
ubuntu at neander:~$

** Tags removed: verification-needed verification-needed-xenial
** Tags added: verification-done verification-done-xenial

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https://bugs.launchpad.net/bugs/1695093

Title:
  arm64: "unsupported RELA relocation: 275" loading certain modules

Status in Linux:
  In Progress
Status in gcc-5 package in Ubuntu:
  Fix Released
Status in gcc-6 package in Ubuntu:
  Fix Released
Status in linux package in Ubuntu:
  Triaged
Status in gcc-5 source package in Xenial:
  Fix Committed
Status in gcc-6 source package in Xenial:
  Invalid
Status in linux source package in Xenial:
  Triaged
Status in gcc-5 source package in Yakkety:
  Won't Fix
Status in gcc-6 source package in Yakkety:
  Won't Fix
Status in linux source package in Yakkety:
  Won't Fix
Status in gcc-5 source package in Zesty:
  Triaged
Status in gcc-6 source package in Zesty:
  Triaged
Status in linux source package in Zesty:
  Triaged

Bug description:
  [Impact]
  Certain kernel modules are unloadable (libceph & scsi_debug) due to the compiler generating unsupported relocations.

  This symptom is similar to LP: #1533009 but, in that case it impacted
  all modules, and the fix for that appears to remain in place.

  [Test Case]

  With the hwe-z kernel:

  ubuntu at grotian:~$ sudo modprobe libceph
  modprobe: ERROR: could not insert 'libceph': Exec format error
  ubuntu at grotian:~$ dmesg
  [66988.470307] module libceph: unsupported RELA relocation: 275

  [Regression Risk]
  The scope of the fix is restricted to aarch64, so regressions should only impact the arm64 port of Ubuntu. Regressions could impact when literal loads are used - which may have performance impacts or possibly cause software to fail to build/run where it previously did. This is somewhat mitigated by the fact that this has been fixed in artful gcc-5/gcc-6 and used on our buildds for some time. Only "somewhat", because gcc-7 is now the default.

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