[SRU][Bionic][PATCH 0/2] Fixes for LP:1773162

[Joseph Salisbury]

BugLink: http://bugs.launchpad.net/bugs/1773162

== SRU Justification ==
IBM reports that 4.15.0-22-generic fails to boot on IBM S822LC (POWER8 
(raw), altivec supported).  The system then gets stuck in a reboot
cycle.

It was found that Bionic commit 06f7e3d39f2f was the cause of this
regression.  IBM believes the backport of this commit for CVE-2018-3639 (powerpc) was
done incorrectly.  

I reverted the backport of commit 06f7e3d39f2f.  I then performed a new
backport of mainline commit a048a07d7f45.  I built a test kernel for IBM
who tested this kernel.  It was reported this new backport resolves the
bug.

== Fixes ==
Revert "powerpc/64s: Add support for a store forwarding barrier at kernel entry/exit"
a048a07d7f45 ("powerpc/64s: Add support for a store forwarding barrier at kernel entry/exit")

== Regression Potential ==
Low.  Fixes a regression and limited to powerpc.

== Test Case ==
A test kernel was built with the revert and second backport. IBM tested
this new patch and stated the test kernel resolved the bug.

Joseph Salisbury (1):
  Revert "powerpc/64s: Add support for a store forwarding barrier at
    kernel entry/exit"

Nicholas Piggin (1):
  powerpc/64s: Add support for a store forwarding barrier at kernel
    entry/exit

 arch/powerpc/include/asm/exception-64s.h     |   6 +-
 arch/powerpc/include/asm/security_features.h |  11 ++
 arch/powerpc/include/asm/setup.h             |  12 +--
 arch/powerpc/kernel/security.c               | 149 +++++++++++++++++++++++++++
 arch/powerpc/kernel/setup_64.c               | 119 +--------------------
 arch/powerpc/lib/feature-fixups.c            |  16 ++-
 arch/powerpc/platforms/powernv/setup.c       |   2 +-
 7 files changed, 183 insertions(+), 132 deletions(-)

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2.7.4