[PATCH v3 0/5] x86 entry stuff, maybe for 4.4

Andy Lutomirski
2015-11-12T20:59:10Z

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 Frédéric 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 v3: Actually send entire series (patch 1 was missing)

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 (5):
x86/entry/64: Fix irqflag tracing wrt context tracking
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 | 27 +++++++++++----
arch/x86/include/asm/jump_label.h | 63 ++++++++++++++++++++++++++++++----
include/linux/context_tracking_state.h | 4 +--
kernel/context_tracking.c | 4 +--
5 files changed, 95 insertions(+), 18 deletions(-)

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2.5.0