hardware-assisted lock elision hazardous on x86

[Chris J Arges]

[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.

[Chris J Arges (arges)]

Uploaded for trusty/utopic.

[Brian Murray (brian-murray)]

Hello Chris, or anyone else affected,

Accepted glibc into utopic-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/glibc/2.19-10ubuntu2.2 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, and change the tag from verification-needed to verification-done. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed. In either case, details of your testing will help us make a better decision.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance!

[Brian Murray (brian-murray)]

Hello Chris, or anyone else affected,

Accepted eglibc into trusty-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/eglibc/2.19-0ubuntu6.5 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, and change the tag from verification-needed to verification-done. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed. In either case, details of your testing will help us make a better decision.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance!

[Chris J Arges (arges)]

Ok I was able to verify this for utopic with the following:
1) reproduce bug 1370352 by installing intel-microcode 2.20140913.1ubuntu1
2) install -proposed glibc
3) try to reproduce bug, and now it works!

Trusty doesn't reproduce bug 1370352 (maybe because we're not triggering the right kind of pthread programs when we update microcode). But -proposed onto trusty didn't cause any issues and I was able to update microcodes as normal.

[Chris J Arges (arges)]

Note, I still recommend we patch this for Trusty as well as a precaution. While I was unable to trigger it, a user could easily introduce programs that leverage pthreads in a way to trigger this when we do the microcode update.

[Launchpad Janitor (janitor)]

This bug was fixed in the package eglibc - 2.19-0ubuntu6.5

---------------
eglibc (2.19-0ubuntu6.5) trusty; urgency=medium

  * patches/amd64/local-blacklist-on-TSX-Haswell.diff: new patch from
    Henrique de Moraes Holschuh to disable TSX on processors which might get
    it disabled through a microcode update. (LP: #1398975)
 -- Chris J Arges <email address hidden> Thu, 04 Dec 2014 08:30:10 -0600

[Adam Conrad (adconrad)]

The verification of the Stable Release Update for eglibc has completed successfully and the package has now been released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regressions.

[Launchpad Janitor (janitor)]

This bug was fixed in the package glibc - 2.19-10ubuntu2.2

---------------
glibc (2.19-10ubuntu2.2) utopic; urgency=medium

  * patches/amd64/local-blacklist-on-TSX-Haswell.diff: new patch from
    Henrique de Moraes Holschuh to disable TSX on processors which might get
    it disabled through a microcode update. (LP: #1398975)
 -- Chris J Arges <email address hidden> Thu, 04 Dec 2014 10:13:13 -0600