It's forbidden to take the page_table_lock with the irq disabled
or if there's contention the IPIs (for tlb flushes) sent with
the page_table_lock held will never run leading to a deadlock.

Nobody takes the pgd_lock from irq context so the _irqsave can be
removed.
Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Acked-by: NRik van Riel <riel@redhat.com>
Tested-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: <stable@kernel.org>
LKML-Reference: <201102162345.p1GNjMjm021738@imap1.linux-foundation.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

mm_fault_error() should not execute oom-killer, if page fault
occurs in kernel space.  E.g. in copy_from_user()/copy_to_user().

This would happen if we find ourselves in OOM on a
copy_to_user(), or a copy_from_user() which faults.

Without this patch, the kernels hangs up in copy_from_user(),
because OOM killer sends SIG_KILL to current process, but it
can't handle a signal while in syscall, then the kernel returns
to copy_from_user(), reexcute current command and provokes
page_fault again.

With this patch the kernel return -EFAULT from copy_from_user().

The code, which checks that page fault occurred in kernel space,
has been copied from do_sigbus().

This situation is handled by the same way on powerpc, xtensa,
tile, ...
Signed-off-by: NAndrey Vagin <avagin@openvz.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: <stable@kernel.org>
LKML-Reference: <201103092322.p29NMNPH001682@imap1.linux-foundation.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

access_error() already takes error_code as an argument, so there is
no need for an additional write flag.
Signed-off-by: NMichel Lespinasse <walken@google.com>
Acked-by: NRik van Riel <riel@redhat.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Acked-by: NWu Fengguang <fengguang.wu@intel.com>
Cc: Ying Han <yinghan@google.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Acked-by: N"H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This change reduces mmap_sem hold times that are caused by waiting for
disk transfers when accessing file mapped VMAs.

It introduces the VM_FAULT_ALLOW_RETRY flag, which indicates that the call
site wants mmap_sem to be released if blocking on a pending disk transfer.
In that case, filemap_fault() returns the VM_FAULT_RETRY status bit and
do_page_fault() will then re-acquire mmap_sem and retry the page fault.

It is expected that the retry will hit the same page which will now be
cached, and thus it will complete with a low mmap_sem hold time.

Tests:

- microbenchmark: thread A mmaps a large file and does random read accesses
  to the mmaped area - achieves about 55 iterations/s. Thread B does
  mmap/munmap in a loop at a separate location - achieves 55 iterations/s
  before, 15000 iterations/s after.

- We are seeing related effects in some applications in house, which show
  significant performance regressions when running without this change.

[akpm@linux-foundation.org: fix warning & crash]
Signed-off-by: NMichel Lespinasse <walken@google.com>
Acked-by: NRik van Riel <riel@redhat.com>
Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Reviewed-by: NWu Fengguang <fengguang.wu@intel.com>
Cc: Ying Han <yinghan@google.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Acked-by: N"H. Peter Anvin" <hpa@zytor.com>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

arch/x86/mm/fault.c: In function 'vmalloc_sync_all':
arch/x86/mm/fault.c:238: warning: assignment makes integer from pointer without a cast

introduced by 617d34d9.
Signed-off-by: NBorislav Petkov <borislav.petkov@amd.com>
LKML-Reference: <20101020103642.GA3135@kryptos.osrc.amd.com>
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>

Take mm->page_table_lock while syncing the vmalloc region.  This prevents
a race with the Xen pagetable pin/unpin code, which expects that the
page_table_lock is already held.  If this race occurs, then Xen can see
an inconsistent page type (a page can either be read/write or a pagetable
page, and pin/unpin converts it between them), which will cause either
the pin or the set_p[gm]d to fail; either will crash the kernel.

vmalloc_sync_all() should be called rarely, so this extra use of
page_table_lock should not interfere with its normal users.

The mm pointer is stashed in the pgd page's index field, as that won't
be otherwise used for pgds.
Reported-by: NIan Campbell <ian.cambell@eu.citrix.com>
Originally-by: NJan Beulich <jbeulich@novell.com>
LKML-Reference: <4CB88A4C.1080305@goop.org>
Signed-off-by: NJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>

In x86, faults exit by executing the iret instruction, which then
reenables NMIs if we faulted in NMI context. Then if a fault
happens in NMI, another NMI can nest after the fault exits.

But we don't yet support nested NMIs because we have only one NMI
stack. To prevent from that, check that vmalloc and kmemcheck
faults don't happen in this context. Most of the other kernel faults
in NMIs can be more easily spotted by finding explicit
copy_from,to_user() calls on review.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>

An earlier patch fixed the hwpoison fault handling to encode the
huge page size in the fault code of the page fault handler.

This is needed to report this information in SIGBUS to user space.

This is a straight forward patch to pass this information
through to the signal handling in the x86 specific fault.c

Cc: x86@kernel.org
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: fengguang.wu@intel.com
Signed-off-by: NAndi Kleen <ak@linux.intel.com>

pte_present() returns true even present bit isn't set but _PAGE_PROTNONE
(global bit) bit is set. While with CONFIG_DEBUG_PAGEALLOC, free pages have
global bit set but present bit clear. This patch makes we could catch
free pages access with CONFIG_DEBUG_PAGEALLOC enabled.

[ hpa: added a comment in the code as a warning to janitors ]
Signed-off-by: NShaohua Li <shaohua.li@intel.com>
LKML-Reference: <1280217988.32400.75.camel@sli10-desk.sh.intel.com>
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>

No behavior change.

Move some of vmalloc_sync_all() code into a new function
sync_global_pgds() that will be useful for memory hotplug.
Signed-off-by: NHaicheng Li <haicheng.li@linux.intel.com>
LKML-Reference: <4C6E4ECD.1090607@linux.intel.com>
Reviewed-by: NWu Fengguang <fengguang.wu@intel.com>
Reviewed-by: NAndi Kleen <ak@linux.intel.com>
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>

It's wrong for several reasons, but the most direct one is that the
fault may be for the stack accesses to set up a previous SIGBUS.  When
we have a kernel exception, the kernel exception handler does all the
fixups, not some user-level signal handler.

Even apart from the nested SIGBUS issue, it's also wrong to give out
kernel fault addresses in the signal handler info block, or to send a
SIGBUS when a system call already returns EFAULT.
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

init_task doesn't get its stack end location set to
STACK_END_MAGIC, and hence the message is confusing
rather than helpful in this case.
Signed-off-by: NJan Beulich <jbeulich@novell.com>
LKML-Reference: <4B06AEFE02000078000211F4@vpn.id2.novell.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Bye-bye Performance Counters, welcome Performance Events!

In the past few months the perfcounters subsystem has grown out its
initial role of counting hardware events, and has become (and is
becoming) a much broader generic event enumeration, reporting, logging,
monitoring, analysis facility.

Naming its core object 'perf_counter' and naming the subsystem
'perfcounters' has become more and more of a misnomer. With pending
code like hw-breakpoints support the 'counter' name is less and
less appropriate.

All in one, we've decided to rename the subsystem to 'performance
events' and to propagate this rename through all fields, variables
and API names. (in an ABI compatible fashion)

The word 'event' is also a bit shorter than 'counter' - which makes
it slightly more convenient to write/handle as well.

Thanks goes to Stephane Eranian who first observed this misnomer and
suggested a rename.

User-space tooling and ABI compatibility is not affected - this patch
should be function-invariant. (Also, defconfigs were not touched to
keep the size down.)

This patch has been generated via the following script:

  FILES=$(find * -type f | grep -vE 'oprofile|[^K]config')

  sed -i \
    -e 's/PERF_EVENT_/PERF_RECORD_/g' \
    -e 's/PERF_COUNTER/PERF_EVENT/g' \
    -e 's/perf_counter/perf_event/g' \
    -e 's/nb_counters/nb_events/g' \
    -e 's/swcounter/swevent/g' \
    -e 's/tpcounter_event/tp_event/g' \
    $FILES

  for N in $(find . -name perf_counter.[ch]); do
    M=$(echo $N | sed 's/perf_counter/perf_event/g')
    mv $N $M
  done

  FILES=$(find . -name perf_event.*)

  sed -i \
    -e 's/COUNTER_MASK/REG_MASK/g' \
    -e 's/COUNTER/EVENT/g' \
    -e 's/\<event\>/event_id/g' \
    -e 's/counter/event/g' \
    -e 's/Counter/Event/g' \
    $FILES

... to keep it as correct as possible. This script can also be
used by anyone who has pending perfcounters patches - it converts
a Linux kernel tree over to the new naming. We tried to time this
change to the point in time where the amount of pending patches
is the smallest: the end of the merge window.

Namespace clashes were fixed up in a preparatory patch - and some
stylistic fallout will be fixed up in a subsequent patch.

( NOTE: 'counters' are still the proper terminology when we deal
  with hardware registers - and these sed scripts are a bit
  over-eager in renaming them. I've undone some of that, but
  in case there's something left where 'counter' would be
  better than 'event' we can undo that on an individual basis
  instead of touching an otherwise nicely automated patch. )
Suggested-by: NStephane Eranian <eranian@google.com>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: NPaul Mackerras <paulus@samba.org>
Reviewed-by: NArjan van de Ven <arjan@linux.intel.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: <linux-arch@vger.kernel.org>
LKML-Reference: <new-submission>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Add VM_FAULT_HWPOISON handling to the x86 page fault handler. This is
very similar to VM_FAULT_OOM, the only difference is that a different
si_code is passed to user space and the new addr_lsb field is initialized.

v2: Make the printk more verbose/unique

Cc: x86@kernel.org
Signed-off-by: NAndi Kleen <ak@linux.intel.com>

Add __kprobes to the functions which handle in-kernel fixable page
faults. Since kprobes can cause those in-kernel page faults by accessing
kprobe data structures, probing those fault functions will cause
fault-int3-loop (do_page_fault has already been marked as __kprobes).
Signed-off-by: NMasami Hiramatsu <mhiramat@redhat.com>
Acked-by: NAnanth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
LKML-Reference: <20090827172311.8246.92725.stgit@localhost.localdomain>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>

Since commit 5fd29d6c ("printk: clean up handling of log-levels
and newlines"), the kernel logs segfaults like:

    <6>gnome-power-man[24509]: segfault at 20 ip 00007f9d4950465a sp 00007fffbb50fc70 error 4 in libgobject-2.0.so.0.2103.0[7f9d494f7000+45000]

with the extra "<6>" being KERN_INFO.  This happens because the
printk in show_signal_msg() started with KERN_CONT and then
used "%s" to pass in the real level; and KERN_CONT is no longer
an empty string, and printk only pays attention to the level at
the very beginning of the format string.

Therefore, remove the KERN_CONT from this printk, since it is
now actively causing problems (and never really made any
sense).
Signed-off-by: NRoland Dreier <roland@digitalvampire.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <874otjitkj.fsf@shaolin.home.digitalvampire.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Commit 5fd29d6c ("printk: clean up
handling of log-levels and newlines") changed printk semantics.  printk
lines with multiple KERN_<level> prefixes are no longer emitted as
before the patch.

<level> is now included in the output on each additional use.

Remove all uses of multiple KERN_<level>s in formats.
Signed-off-by: NJoe Perches <joe@perches.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Use pgtable access helpers for 32-bit version dump_pagetable()
and get rid of __typeof__() operators. This needs to make
pmd_pfn() available for 2-level pgtable.

Also, remove some casts for 64-bit version dump_pagetable().
Signed-off-by: NAkinobu Mita <akinobu.mita@gmail.com>
LKML-Reference: <20090627063514.GA2834@localhost.localdomain>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

This allows the callers to now pass down the full set of FAULT_FLAG_xyz
flags to handle_mm_fault().  All callers have been (mechanically)
converted to the new calling convention, there's almost certainly room
for architectures to clean up their code and then add FAULT_FLAG_RETRY
when that support is added.
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Prefetch instructions can generate spurious faults on certain
models of older CPUs. The faults themselves cannot be stopped
and they can occur pretty much anywhere - so the way we solve
them is that we detect certain patterns and ignore the fault.

There is one small path of code where we must not take faults
though: the #PF handler execution leading up to the reading
of the CR2 (the faulting address). If we take a fault there
then we destroy the CR2 value (with that of the prefetching
instruction's) and possibly mishandle user-space or
kernel-space pagefaults.

It turns out that in current upstream we do exactly that:

	prefetchw(&mm->mmap_sem);

	/* Get the faulting address: */
	address = read_cr2();

This is not good.

So turn around the order: first read the cr2 then prefetch
the lock address. Reading cr2 is plenty fast (2 cycles) so
delaying the prefetch by this amount shouldnt be a big issue
performance-wise.

[ And this might explain a mystery fault.c warning that sometimes
  occurs on one an old AMD/Semptron based test-system i have -
  which does have such prefetch problems. ]

Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Vegard Nossum <vegard.nossum@gmail.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>
LKML-Reference: <20090616030522.GA22162@Krystal>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

The hooks that we modify are:
- Page fault handler (to handle kmemcheck faults)
- Debug exception handler (to hide pages after single-stepping
  the instruction that caused the page fault)

Also redefine memset() to use the optimized version if kmemcheck is
enabled.

(Thanks to Pekka Enberg for minimizing the impact on the page fault
handler.)

As kmemcheck doesn't handle MMX/SSE instructions (yet), we also disable
the optimized xor code, and rely instead on the generic C implementation
in order to avoid false-positive warnings.
Signed-off-by: NVegard Nossum <vegardno@ifi.uio.no>

[whitespace fixlet]
Signed-off-by: NPekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

[rebased for mainline inclusion]
Signed-off-by: NVegard Nossum <vegardno@ifi.uio.no>

Pure renames only, to PERF_COUNT_HW_* and PERF_COUNT_SW_*.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Andrew pointed out that the 'once' variable has a needlessly
function-global scope. We can in fact eliminate it completely,
via the use of printk_once().

[ Impact: cleanup ]
Reported-by: NAndrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Paul suggested we allow for data addresses to be recorded along with
the traditional IPs as power can provide these.

For now, only the software pagefault events provide data addresses,
but in the future power might as well for some events.

x86 doesn't seem capable of providing this atm.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090408130409.394816925@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Provide separate sw counters for major and minor page faults.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

We use the generic software counter infrastructure to provide
page fault events.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: cleanup

Eliminate more than 20 unnecessary #include lines in fault.c

Also fix include file dependency bug in asm/traps.h. (this was
masked before, by implicit inclusion)
Signed-off-by: NIngo Molnar <mingo@elte.hu>
LKML-Reference: <tip-56aea8468746e673a4bf50b6a13d97b2d1cbe1e8@git.kernel.org>
Acked-by: NH. Peter Anvin <hpa@linux.intel.com>

Impact: simplification, robustness

Make paravirt_lazy_mode() always return PARAVIRT_LAZY_NONE
when in an interrupt.  This prevents interrupt code from
accidentally inheriting an outer lazy state, and instead
does everything synchronously.  Outer batched operations
are left deferred.
Signed-off-by: NJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Thomas Gleixner <tglx@linutronix.de>

Clarify the kmmio_fault() comment.
Acked-by: NPekka Paalanen <pq@iki.fi>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: extend prefetch handling on 64-bit

Currently there's an extra is_prefetch() check done in do_sigbus(),
which we only do on 32 bits.

This is a last-ditch check before we terminate a task, so it's worth
giving prefetch instructions another chance - should none of our
existing quirks have caught a prefetch instruction related spurious
fault.

The only risk is if a prefetch causes a real sigbus, in that case
we'll not OOM but try another fault. But this code has been on
32-bit for a long time, so it should be fine in practice.

So do this on 64-bit too - and thus remove one more #ifdef.

Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: cleanup

Removal of an #ifdef in fault_in_kernel_space(), by making
use of the new TASK_SIZE_MAX symbol which is now available
on 32-bit too.

Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: cleanup

Rename TASK_SIZE64 to TASK_SIZE_MAX, and provide the
define on 32-bit too. (mapped to TASK_SIZE)

This allows 32-bit code to make use of the (former-) TASK_SIZE64
symbol as well, in a clean way.

Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: cleanup

do_page_fault() has this ugly #ifdef in its prototype:

  #ifdef CONFIG_X86_64
  asmlinkage
  #endif
  void __kprobes do_page_fault(struct pt_regs *regs, unsigned long error_code)

Replace it with 'dotraplinkage' which maps to exactly the above
construct: nothing on 32-bit and asmlinkage on 64-bit.

Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: add oops-recursion check to 32-bit

Unify the oops state-machine, to the 64-bit version. It is
slightly more careful in that it does a recursion check
in oops_begin(), and is thus more likely to show the relevant
oops.

It also means that 32-bit will print one more line at the
end of pagefault triggered oopses:

 	printk(KERN_EMERG "CR2: %016lx\n", address);

Which is generally good information to be seen in partial-dump
digital-camera jpegs ;-)

The downside is the somewhat more complex critical path. Both
variants have been tested well meanwhile by kernel developers
crashing their boxes so i dont think this is a practical worry.

This removes 3 ugly #ifdefs from no_context() and makes the
function a lot nicer read.

Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: refine/extend page fault related oops printing on 64-bit

 - honor the pause_on_oops logic on 64-bit too
 - print out NX fault warnings on 64-bit as well
 - factor out the NX fault message to make it git-greppable and readable

Note that this means that we do the PF_INSTR check on 32-bit non-PAE
as well where it should not occur ... normally. Cannot hurt.

Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: cleanup

Avoid a couple more #ifdefs by moving fundamentally non-unifiable
functions into a single #ifdef 32-bit / #else / #endif block in
fault.c: vmalloc*(), dump_pagetable(), check_vm8086_mode().

No code changed:

   text	   data	    bss	    dec	    hex	filename
   4618	     32	     24	   4674	   1242	fault.o.before
   4618	     32	     24	   4674	   1242	fault.o.after

Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: cleanup

Remove an #ifdef from notify_page_fault(). The function still
compiles to nothing in the !CONFIG_KPROBES case.

Introduce kprobes_built_in() and kprobe_fault_handler() helpers
to allow this - they returns 0 if !CONFIG_KPROBES.

No code changed:

   text	   data	    bss	    dec	    hex	filename
   4618	     32	     24	   4674	   1242	fault.o.before
   4618	     32	     24	   4674	   1242	fault.o.after

Cc: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: cleanup

Remove an #ifdef from kmmio_fault() - we can do this by
providing default implementations for is_kmmio_active()
and kmmio_handler(). The compiler optimizes it all away
in the !CONFIG_MMIOTRACE case.

Also, while at it, clean up mmiotrace.h a bit:

 - standard header guards
 - standard vertical spaces for structure definitions

No code changed (both with mmiotrace on and off in the config):

   text	   data	    bss	    dec	    hex	filename
   2947	     12	     12	   2971	    b9b	fault.o.before
   2947	     12	     12	   2971	    b9b	fault.o.after

Cc: Pekka Paalanen <pq@iki.fi>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: improve page fault handling robustness

The 'PF_RSVD' flag (bit 3) of the page-fault error_code is a
relatively recent addition to x86 CPUs, so the 32-bit do_fault()
implementation never had it. This flag gets set when the CPU
detects nonzero values in any reserved bits of the page directory
entries.

Extend the existing 64-bit check for PF_RSVD in do_page_fault()
to 32-bit too. If we detect such a fault then we print a more
informative oops and the pagetables.

This unifies the code some more, removes an ugly #ifdef and improves
the 32-bit page fault code robustness a bit. It slightly increases
the 32-bit kernel text size.

Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>