[Bug 1398975] Re: hardware-assisted lock elision hazardous on x86

[Mathew Hodson]

** No longer affects: eglibc (Ubuntu)

** Changed in: glibc (Ubuntu)
   Importance: Undecided => Medium

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https://bugs.launchpad.net/bugs/1398975

Title:
  hardware-assisted lock elision hazardous on x86

Status in glibc package in Ubuntu:
  Fix Released
Status in eglibc source package in Trusty:
  Fix Released
Status in glibc source package in Utopic:
  Fix Released
Status in glibc package in Debian:
  Fix Released

Bug description:
  [Impact]
  See https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=762195 for a full description of the issue.
  HLE extensions are hazardous due to erratum HSD136.

  Users that upgrade their intel-microcode could encounter illegal
  instruction traps due to microcode updates that blacklist HLE
  instructions. Glibc uses those instructions and thus we need to be
  defensive and patch them here.

  The issue was originally seen here:
  https://bugs.launchpad.net/intel/+bug/1370352

  [Test Case]
  Update to latest intel-microcode with microcode-20140913.dat enabled. Try to boot machine and use applications; check dmesg for trap invalid opcodes in libpthread-2.19.so.

  [Regression Potential]
  This has been fixed in vivid, so I'm requesting this patch be backported to T/U.

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