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[PATCH 0/4] x86: Tweaks for UMIP

Now that the support for UMIP [1], [2] has been merged in the tip tree,
this series add a couple of tweaks.

Ingo asked for two small additions to select UMIP by default when building
and inform of this feature being enabled [3].

Also, Linus suggested to issue a rate-limited warning whenever the any of
the instructions that UMIP protects are used by user space programs [4].
This is useful to give programs a hint on the reason for which they start
seeing an unexpected SIGSEGV signal. Also, it helps to encourage updates
to those programs and avoid using these instructions if possible.

Thanks and BR,

[1]. https://lkml.org/lkml/2017/10/27/699
[2]. https://www.mail-archive.com/linux-kernel@xxxxxxxxxxxxxxx/msg1523438.html
[3]. https://lkml.org/lkml/2017/11/8/238
[4]. https://lkml.org/lkml/2017/11/8/593

Ricardo Neri (4):
  x86/umip: Select X86_INTEL_UMIP by default
  x86/umip: Inform that UMIP has been enabled
  x86/umip: Identify the str and sldt instructions
  x86/umip: Warn if UMIP-protected instructions are used

 arch/x86/Kconfig             | 10 ++++-
 arch/x86/kernel/cpu/common.c |  2 +
 arch/x86/kernel/umip.c       | 88 +++++++++++++++++++++++++++++++++++++-------
 3 files changed, 85 insertions(+), 15 deletions(-)