Re: [GIT PULL] x86/entry changes for 3.20, round 1

["Paul E. McKenney" <paulmck@linux.vnet.ibm.com>]

On Wed, Jan 14, 2015 at 05:59:26PM -0800, Andy Lutomirski wrote:
> Hi Ingo and Thomas,
> 
> At Linus' suggestion, I'm trying out some maintainerish stuff for x86
> entry code.  Please consider pulling to an appropriate branch *after
> Paul sends his RCU pull request*, only if 734d16801349 is included in
> that pull request.  If this goes well, maybe I'll submit a MAINTAINERS
> patch, too.
> 
> IMPORTANT: This is based on an RCU change that you don't have yet.  I
> think that Paul is planning on sending a pull request with that change
> fairly soon.  The code in here would compile without that fix, but it
> would introduce a nasty regression, so, to avoid breaking bisection, I
> based this off of the relevant change in Paul's tree.  (It's the very
> first change for 3.20 in his current queue.)

Yep, should happen by early next week, if it survives this weekend's
testing.  ;-)

							Thanx, Paul

> If you want me to structure this differently, let me know.
> 
> I may have one more entry pull request before the merge window if I
> can get my sysret stuff reviewed in time.  Not sure yet.  I may also
> be comfortable with some more of Denys' cleanups in time.
> 
> The following changes since commit 734d16801349fbe951d2f780191d32c5b8a892d1:
> 
>   rcu: Make rcu_nmi_enter() handle nesting (2014-12-30 17:40:16 -0800)
> 
> are available in the git repository at:
> 
>   git://git.kernel.org/pub/scm/linux/kernel/git/luto/linux.git
> tags/pr-20150114-x86-entry
> 
> for you to fetch changes up to f6f64681d9d87ded48a90b644b2991c6ee05da2d:
> 
>   x86: entry_64.S: fold SAVE_ARGS_IRQ macro into its sole user
> (2015-01-13 14:18:08 -0800)
> 
> ----------------------------------------------------------------
> This is my accumulated x86 entry work, part 1, for 3.20.  The meat
> of this is an IST rework.  When an IST exception interrupts user
> space, we will handle it on the per-thread kernel stack instead of
> on the IST stack.  This sounds messy, but it actually simplifies the
> IST entry/exit code, because it eliminates some ugly games we used
> to play in order to handle rescheduling, signal delivery, etc on the
> way out of an IST exception.
> 
> The IST rework introduces proper context tracking to IST exception
> handlers.  I haven't seen any bug reports, but the old code could
> have incorrectly treated an IST exception handler as an RCU extended
> quiescent state.
> 
> The memory failure change (included in this pull request with
> Borislav and Tony's permission) eliminates a bunch of code that
> is no longer needed now that user memory failure handlers are
> called in process context.
> 
> Finally, this includes a few on Denys' uncontroversial and Obviously
> Correct (tm) cleanups.
> 
> The IST and memory failure changes have been in -next for a while.
> 
> LKML references:
> 
> IST rework:
> http://lkml.kernel.org/r/cover.1416604491.git.luto@amacapital.net
> 
> Memory failure change:
> http://lkml.kernel.org/r/54ab2ffa301102cd6e@agluck-desk.sc.intel.com
> 
> Denys' cleanups:
> http://lkml.kernel.org/r/1420927210-19738-1-git-send-email-dvlasenk@redhat.com
> 
> ----------------------------------------------------------------
> Andy Lutomirski (4):
>       x86, entry: Switch stacks on a paranoid entry from userspace
>       x86, traps: Track entry into and exit from IST context
>       x86: Clean up current_stack_pointer
>       x86, traps: Add ist_begin_non_atomic and ist_end_non_atomic
> 
> Denys Vlasenko (3):
>       x86: entry_64.S: delete unused code
>       x86: ia32entry.S: fix wrong symbolic constant usage: R11->ARGOFFSET
>       x86: entry_64.S: fold SAVE_ARGS_IRQ macro into its sole user
> 
> Tony Luck (1):
>       x86, mce: Get rid of TIF_MCE_NOTIFY and associated mce tricks
> 
>  Documentation/x86/entry_64.txt         |  18 ++-
>  Documentation/x86/x86_64/kernel-stacks |   8 +-
>  arch/x86/ia32/ia32entry.S              |   4 +-
>  arch/x86/include/asm/calling.h         |   1 -
>  arch/x86/include/asm/mce.h             |   1 -
>  arch/x86/include/asm/thread_info.h     |  15 ++-
>  arch/x86/include/asm/traps.h           |   6 +
>  arch/x86/kernel/cpu/mcheck/mce.c       | 114 +++++-------------
>  arch/x86/kernel/cpu/mcheck/p5.c        |   6 +
>  arch/x86/kernel/cpu/mcheck/winchip.c   |   5 +
>  arch/x86/kernel/entry_64.S             | 208 ++++++++++++++-------------------
>  arch/x86/kernel/irq_32.c               |  13 +--
>  arch/x86/kernel/signal.c               |   6 -
>  arch/x86/kernel/traps.c                | 108 +++++++++++++----
>  14 files changed, 252 insertions(+), 261 deletions(-)
>