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[Bug 1400349] Re: [SRU] new arm64 optimized copy_to_user and copy_from_user assembly code

 

This bug is awaiting verification that the kernel in -proposed solves
the problem. Please test the kernel and update this bug with the
results. If the problem is solved, change the tag 'verification-needed-
trusty' to 'verification-done-trusty'.

If verification is not done by 5 working days from today, this fix will
be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how
to enable and use -proposed. Thank you!


** Tags added: verification-needed-trusty

** Tags added: verification-needed-utopic

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Title:
  [SRU] new arm64 optimized copy_to_user and copy_from_user assembly
  code

Status in linux package in Ubuntu:
  Fix Committed
Status in linux source package in Trusty:
  Fix Committed
Status in linux source package in Utopic:
  Fix Committed

Bug description:
  [Impact]
  The copy_{to,from}_user implementations in the Ubuntu kernel are suboptimal. Optimized implementations have been submitted upstream and have shown a significant improvement in network performance.

  [Test Case]
  Generate traffic from one node to another using iperf.

  [Regression Risk]
  These functions are obviously used heavily throughout the kernel, so a defect here could have significant impact. This risk is mitigated by using an implementation heavily based on the linaro string libraries (which are used in other places already, e.g. glibc), and through active testing of this patch on real hardware using a trusty-kernel base. The new patch will also undergo regression testing to ensure the memory corruption issue of the previous patch does not exist.

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References