[PATCH v2 0/4] x86 entry stuff, maybe for 4.4

[Andy Lutomirski]

The first patch is a bit ugly, but it fixes a bug that could affect
lockdep.  That bug is very minor and may not be observable at all,
but I don't really want to bet on it.

The other three are intended to fix a performance regression in the
entry rework that FrÃdÃric objected to.  They're much later than I'd
like to have sent them for 4.4, but they're kind-of sort-of
regression fixes, so maybe they're still okay.  They would certainly
need careful review, though.

I don't have a great benchmark for them.  The biggest impact is
likely to be to user page fault latency on CONFIG_CONTEXT_TRACKING=y
kernels (i.e. distro kernels) that don't use context tracking
(i.e. most users).

Changes from v1:
 - CALL_ENTER_FROM_USER_MODE is now CALL_enter_from_user_mode (Ingo)
 - STATIC_JUMP_IF_{TRUE,FALSE} now cannot be (mis-)used on non-jump-label
   kernels (Thomas)
 - Comments are better (Borislav)

This doesn't really address Thomas' objections to the HAVE_JUMP_LABEL stuff,
but it's more robust now, and maybe that's good enough.

Andy Lutomirski (4):
  context_tracking: Switch to new static_branch API
  x86/asm: Error out if asm/jump_label.h is included inappropriately
  x86/asm: Add asm macros for static keys/jump labels
  x86/entry/64: Bypass enter_from_user_mode on non-context-tracking
    boots

 arch/x86/entry/calling.h               | 15 ++++++++
 arch/x86/entry/entry_64.S              |  8 ++---
 arch/x86/include/asm/jump_label.h      | 63 ++++++++++++++++++++++++++++++----
 include/linux/context_tracking_state.h |  4 +--
 kernel/context_tracking.c              |  4 +--
 5 files changed, 77 insertions(+), 17 deletions(-)

-- 
2.5.0

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