UBUNTU: Start new release

Ignore: yes
x86_64, traps: Stop using IST for #SS

On a 32-bit kernel, this has no effect, since there are no IST stacks.

On a 64-bit kernel, #SS can only happen in user code, on a failed iret
to user space, a canonical violation on access via RSP or RBP, or a
genuine stack segment violation in 32-bit kernel code.  The first two
cases don't need IST, and the latter two cases are unlikely fatal bugs,
and promoting them to double faults would be fine.

This fixes a bug in which the espfix64 code mishandles a stack segment
violation.

This saves 4k of memory per CPU and a tiny bit of code.

Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
(cherry picked from commit 6f442be2fb22be02cafa606f1769fa1e6f894441)
CVE-2014-9090
BugLink: http://bugs.launchpad.net/bugs/1398795
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
UBUNTU: Ubuntu-3.16.0-27.36

Signed-off-by: Luis Henriques <luis.henriques@canonical.com>