On recommendation from Andi Kleen share a few more options
between 32 and 64 bit builds.
A defconfig build for i386 did not show any difference in
size of text and data.

The additional shared options are:
-Wno-sign-compare
-fno-asynchronous-unwind-tables
-mno-sse
-mno-mmx
-mno-sse2
-mno-3dnow
Signed-off-by: NSam Ravnborg <sam@ravnborg.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Unify the 32 and 64 bit specific Makefiles.
The unification was simplest to do in one step although the
readability of the patch suffers a bit from this.

Noteworthy remarks on the unification:
- The 64 bit cpu stuff should be moved to Makefile_32.cpu
  but I did not feel confident doing it due to subtle differences
- The use of cflags-y were abandoned since we have seen one bug where
  we did wrong due to missing assignment to KBUILD_CFLAGS.
  The cc-option marcro uses KBUILD_CFLAGS.
- The "No need to remake" line are deleted. It caused "make -B" to fail
- For 64 bit the sub architecture stuff is not used.
- The way head64.o is specified could be nicer - but it awaits the
  introduction of head32.o (which seems like a win to introduce for readability)
- Patch is checkpatch clean

Patch is tested by doing a defconfig build for i386 and x86_64 and in both
cases monitoring that only relevant files were recompiled when applying
the patch.

[ mingo@elte.hu: build fix ]
Signed-off-by: NSam Ravnborg <sam@ravnborg.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Make the control flow of kprobe_handler more obvious.

Collapse the separate if blocks/gotos with if/else blocks
this unifies the duplication of the check for a breakpoint
instruction race with another cpu.

Create two jump targets:
	preempt_out: re-enables preemption before returning ret
	out: only returns ret
Signed-off-by: NHarvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

First step towards unifying these files.
- Checkpatch trailing whitespace fixes
- Checkpatch indentation of switch statement fixes
- Checkpatch single statement ifs need no braces fixes
- Checkpatch consistent spacing after comma fixes
- Introduce defines for pagefault error bits from X86_64 and add useful
  comment from X86_32.  Use these defines in X86_32 where obvious.
- Unify comments between 32|64 bit
- Small ifdef movement for CONFIG_KPROBES in notify_page_fault()
- Introduce X86_64 only case statement

No Functional Changes.
Signed-off-by: NHarvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

The functions time_before, time_before_eq, time_after, and time_after_eq
are more robust for comparing jiffies against other values.

A simplified version of the semantic patch making this change is as follows:
(http://www.emn.fr/x-info/coccinelle/)

// <smpl>
@ change_compare_np @
expression E;
@@

(
- jiffies <= E
+ time_before_eq(jiffies,E)
|
- jiffies >= E
+ time_after_eq(jiffies,E)
|
- jiffies < E
+ time_before(jiffies,E)
|
- jiffies > E
+ time_after(jiffies,E)
)

@ include depends on change_compare_np @
@@

#include <linux/jiffies.h>

@ no_include depends on !include && change_compare_np @
@@

  #include <linux/...>
+ #include <linux/jiffies.h>
// </smpl>
Signed-off-by: NJulia Lawall <julia@diku.dk>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

The functions time_before, time_before_eq, time_after, and time_after_eq
are more robust for comparing jiffies against other values.

A simplified version of the semantic patch making this change is as follows:
(http://www.emn.fr/x-info/coccinelle/)

// <smpl>
@ change_compare_np @
expression E;
@@

(
- jiffies <= E
+ time_before_eq(jiffies,E)
|
- jiffies >= E
+ time_after_eq(jiffies,E)
|
- jiffies < E
+ time_before(jiffies,E)
|
- jiffies > E
+ time_after(jiffies,E)
)

@ include depends on change_compare_np @
@@

#include <linux/jiffies.h>

@ no_include depends on !include && change_compare_np @
@@

  #include <linux/...>
+ #include <linux/jiffies.h>
// </smpl>
Signed-off-by: NJulia Lawall <julia@diku.dk>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

The functions time_before, time_before_eq, time_after, and time_after_eq
are more robust for comparing jiffies against other values.

A simplified version of the semantic patch making this change is as follows:
(http://www.emn.fr/x-info/coccinelle/)

// <smpl>
@ change_compare_np @
expression E;
@@

(
- jiffies <= E
+ time_before_eq(jiffies,E)
|
- jiffies >= E
+ time_after_eq(jiffies,E)
|
- jiffies < E
+ time_before(jiffies,E)
|
- jiffies > E
+ time_after(jiffies,E)
)

@ include depends on change_compare_np @
@@

#include <linux/jiffies.h>

@ no_include depends on !include && change_compare_np @
@@

  #include <linux/...>
+ #include <linux/jiffies.h>
// </smpl>

[ mingo@elte.hu: merge to x86.git ]
Signed-off-by: NJulia Lawall <julia@diku.dk>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Move #ifdef around function definiton into the function and
unconditionally return on X86_32.  Saves an ifdef from the
one callsite.

[ mingo@elte.hu: minor cleanup. ]
Signed-off-by: NHarvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Fold some small ifdefs into a helper function.
Signed-off-by: NHarvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

arch/x86/math-emu/errors.c:163: warning: format '%ld' expects type 'long int', but argument 3 has type 'u32'
arch/x86/math-emu/errors.c:175: warning: format '%ld' expects type 'long int', but argument 3 has type 'u32'
arch/x86/math-emu/errors.c:175: warning: format '%ld' expects type 'long int', but argument 4 has type 'u32'
arch/x86/math-emu/errors.c:175: warning: format '%ld' expects type 'long int', but argument 5 has type 'u32'
arch/x86/math-emu/errors.c:175: warning: format '%ld' expects type 'long int', but argument 6 has type 'u32'
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

#88: FILE: arch/x86/kernel/cpu/mcheck/k7.c:34:
+		rdmsr(MSR_IA32_MC0_STATUS+i*4,low, high);
 		                             ^

ERROR: need space after that ',' (ctx:VxV)
#142: FILE: arch/x86/kernel/cpu/mcheck/p4.c:170:
+		rdmsr(MSR_IA32_MC0_STATUS+i*4,low, high);
 		                             ^

ERROR: need space after that ',' (ctx:VxV)
#180: FILE: arch/x86/kernel/cpu/mcheck/p6.c:34:
+		rdmsr(MSR_IA32_MC0_STATUS+i*4,low, high);
 		                             ^

total: 3 errors, 0 warnings, 114 lines checked

Your patch has style problems, please review.  If any of these errors
are false positives report them to the maintainer, see
CHECKPATCH in MAINTAINERS.

Please run checkpatch prior to sending patches

Cc: Min Zhang <mzhang@mvista.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

#40: FILE: arch/x86/kernel/cpu/mcheck/k7.c:46:
+				snprintf (misc, 20, "[%08x%08x]", ahigh, alow);

WARNING: line over 80 characters
#45: FILE: arch/x86/kernel/cpu/mcheck/k7.c:50:
+				snprintf (addr, 24, " at %08x%08x", ahigh, alow);

WARNING: no space between function name and open parenthesis '('
#45: FILE: arch/x86/kernel/cpu/mcheck/k7.c:50:
+				snprintf (addr, 24, " at %08x%08x", ahigh, alow);

WARNING: no space between function name and open parenthesis '('
#48: FILE: arch/x86/kernel/cpu/mcheck/k7.c:52:
+			printk (KERN_EMERG "CPU %d: Bank %d: %08x%08x%s%s\n",

WARNING: no space between function name and open parenthesis '('
#65: FILE: arch/x86/kernel/cpu/mcheck/p4.c:161:
+		printk (KERN_DEBUG "CPU %d: EIP: %08x EFLAGS: %08x\n"

WARNING: no space between function name and open parenthesis '('
#88: FILE: arch/x86/kernel/cpu/mcheck/p4.c:182:
+				snprintf (misc, 20, "[%08x%08x]", ahigh, alow);

WARNING: line over 80 characters
#93: FILE: arch/x86/kernel/cpu/mcheck/p4.c:186:
+				snprintf (addr, 24, " at %08x%08x", ahigh, alow);

WARNING: no space between function name and open parenthesis '('
#93: FILE: arch/x86/kernel/cpu/mcheck/p4.c:186:
+				snprintf (addr, 24, " at %08x%08x", ahigh, alow);

WARNING: no space between function name and open parenthesis '('
#96: FILE: arch/x86/kernel/cpu/mcheck/p4.c:188:
+			printk (KERN_EMERG "CPU %d: Bank %d: %08x%08x%s%s\n",

WARNING: no space between function name and open parenthesis '('
#120: FILE: arch/x86/kernel/cpu/mcheck/p6.c:46:
+				snprintf (misc, 20, "[%08x%08x]", ahigh, alow);

WARNING: line over 80 characters
#125: FILE: arch/x86/kernel/cpu/mcheck/p6.c:50:
+				snprintf (addr, 24, " at %08x%08x", ahigh, alow);

WARNING: no space between function name and open parenthesis '('
#125: FILE: arch/x86/kernel/cpu/mcheck/p6.c:50:
+				snprintf (addr, 24, " at %08x%08x", ahigh, alow);

WARNING: no space between function name and open parenthesis '('
#128: FILE: arch/x86/kernel/cpu/mcheck/p6.c:52:
+			printk (KERN_EMERG "CPU %d: Bank %d: %08x%08x%s%s\n",

total: 0 errors, 13 warnings, 100 lines checked

Your patch has style problems, please review.  If any of these errors
are false positives report them to the maintainer, see
CHECKPATCH in MAINTAINERS.

Please run checkpatch prior to sending patches

Cc: Min Zhang <mzhang@mvista.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

SMP, the machine check exception dispatches all logical processors within a
physical package to the machine-check exception handler, so the printk
within each handler outputs concurrently and makes the output unreadable.
Refer to Intel system programming guide Part 1 Section 7.8.5
http://developer.intel.com/design/processor/manuals/253668.pdfSigned-off-by: NMin Zhang <mzhang@mvista.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

support according to fixes of x86_64 support.

- Delete efi_rt_lock because it is used during system early boot,
  before SMP is initialized.

- Change local_flush_tlb() to __flush_tlb_all() to flush global page
  mapping.

- Clean up includes.

- Revise Kconfig description.

- Enable noefi kernel parameter on i386.
Signed-off-by: NHuang Ying <ying.huang@intel.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

x86_read_per_cpu() and its writeish sister are not present in x86_64. So in
this patch, we replace them with __get_cpu_var(), which is present in both
Signed-off-by: NGlauber de Oliveira Costa <gcosta@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Like i386, x86_64 also need to include its own patching function.
(Well, if you're not in a hurry, and don't care about speed, you don't
really _need_ ;-))

So here they are. Not much different in essence from i386
Signed-off-by: NGlauber de Oliveira Costa <gcosta@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

The core patching code for paravirt is sufficiently different
among i386 and x86_64, and we move them to specific files.
Signed-off-by: NGlauber de Oliveira Costa <gcosta@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

x86_64 needs a potentially larger clobber list than i386, due to its calling
convention. So we add more CLBR_ defines for it.
Note that CLBR_ANY is different for each of the architectures, since it comprises
the notion of "All call clobbers in this architecture"
Signed-off-by: NGlauber de Oliveira Costa <gcosta@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Since the advent of ticket locking, CLI_STRING, STI_STRING, and friends
are not used anymore. They can now be safely deleted.
Signed-off-by: NGlauber de Oliveira Costa <gcosta@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

The assembly code in entry_64.S issues a bunch of privileged instructions,
like cli, sti, swapgs, and others. Paravirt guests are forbidden to do so,
and we then replace them with macros that will do the right thing.
Signed-off-by: NGlauber de Oliveira Costa <gcosta@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

This patch adds paravirt hook for swapgs operation, which is a privileged
operation in x86_64.
Signed-off-by: NGlauber de Oliveira Costa <gcosta@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

i386 has a macro GET_CR0_INTO_EAX, used in early trap handling code.
x86_64 has similar needs, only it needs to put cr2 into rcx. We provide
a macro for such task, in the same way
Signed-off-by: NGlauber de Oliveira Costa <gcosta@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

This patch changes the irq handling function definitions
in paravirt.h (like raw_local_irq_disable) to accomodate for x86_64.
The differences are in the calling convention.
Signed-off-by: NGlauber de Oliveira Costa <gcosta@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

This patch adjust the paravirt macros used in assembly code
to accomodate for x86_64 as well.
Signed-off-by: NGlauber de Oliveira Costa <gcosta@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

To account for differences in x86_64, we change the macros that
create raw instances of the paravirt_patch_site struct.
We need to align 64-pointers to 64-bit boundaries, so we add an alignment
directive. Also, we need to make room for a word-sized pointer,
instead of a fixed 32-bit one
Signed-off-by: NGlauber de Oliveira Costa <gcosta@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

This patch adds a field in pv_cpu_ops for a paravirtualized hook
for rdtscp, needed for x86_64.
Signed-off-by: NGlauber de Oliveira Costa <gcosta@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

write_tsc() does not need to be enclosed in any paravirt closure,
as it uses wrmsr(). So we rip off the duplicate in msr.h
and the definition from paravirt.h
Signed-off-by: NGlauber de Oliveira Costa <gcosta@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

This patch adjust the PVOP_VCALL and PVOP_CALL macros to
work with x86_64. It has a different calling convention, and
we use auxiliary macros to account for both calling conventions
as cleanly as possible

Comments are adjusted accordingly.
Signed-off-by: NGlauber de Oliveira Costa <gcosta@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

This patch changes paravirt_32.c to paravirt.c. The goal
is to have paravirt support in x86_64, so we do it in a common file
Signed-off-by: NGlauber de Oliveira Costa <gcosta@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Establish the user API for sending a user-defined signal to the traced task on a BTS buffer overflow.

This should complete the user API for the BTS ptrace extension.
The patches so far implement wrap-around overflow handling as is needed for debugging.

The remaining open is another overflow handling mechanism that sends a signal to the traced task on a buffer overflow.
This will take some more time from my side.

Since, from a user perspective, this occurs behind the scenes, the patch set should already be useful. More features may/will be added on top of it (overflow signal, pageable back-up buffers, kernel tracing, core file support, profiling, ...).
Signed-off-by: NMarkus Metzger <markus.t.metzger@intel.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Pass the buffer size for (most) ptrace commands that pass user-allocated buffers and check that size before accessing the buffer. Unfortunately, PTRACE_BTS_GET already uses all 4 parameters.
Commands that access user buffers return the number of bytes or records read or written.
Signed-off-by: NMarkus Metzger <markus.t.metzger@intel.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Support BTS recording of 32bit and 64bit tasks from 32bit or 64bit tasks.
Signed-off-by: NMarkus Metzger <markus.t.metzger@intel.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Check the rlimit of the tracing task for total and locked memory when allocating the BTS buffer.
Signed-off-by: NMarkus Metzger <markus.t.metzger@intel.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Move some deeply indented code related to re-entrance processing
from kprobe_handler() to reenter_kprobe().
Signed-off-by: NMasami Hiramatsu <mhiramat@redhat.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

[ mhiramat@redhat.com: updated it to latest x86.git ]

Factor common X86_32, X86_64 kprobe reenter logic from deeply
indented section to helper function.
Signed-off-by: NHarvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>

Fix a preemption bug in kprobe_handler(). It has to call preempt_enable()
before returning.
Signed-off-by: NMasami Hiramatsu <mhiramat@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Aviod TLB flush IPIs during C3 states by voluntary leave_mm()
before entering C3.

The performance impact of TLB flush on C3 should not be significant with
respect to C3 wakeup latency. Also, CPUs tend to flush TLB in hardware while in
C3 anyways.

On a 8 logical CPU system, running make -j2, the number of tlbflush IPIs goes
down from 40 per second to ~ 0. Total number of interrupts during the run
of this workload was ~1200 per second, which makes it ~3% savings in wakeups.

There was no measurable performance or power impact however.

[ akpm@linux-foundation.org: symbol export fixes. ]
Signed-off-by: NVenkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

we use a few static mapping rules in our pirq routing functions,
and for example regression f3ac8432 was due to the pirq
being out of range of the remapping array. Put in a few
WARN_ON_ONCE() lines so that we get notified about any such
out-of-bound incidents.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

increasing number of PCI slots in large multi-node systems.  The kernel
currently attempts by default to allocate memory for all PCI expansion
ROMs so there has also been an increasing number of PCI memory
allocation failures seen on these systems.  This occurs because the BIOS
either (1) provides insufficient PCI memory resource for all the
expansion ROMs or (2) provides adequate PCI memory resource for
expansion ROMs but provides the space in kernel unexpected BIOS assigned
P2P non-prefetch windows.

The resulting PCI memory allocation failures may be benign when related
to memory requests for expansion ROMs themselves but in some cases they
can occur when attempting to allocate space for more critical BARs.
This can happen when a successful expansion ROM allocation request
consumes memory resource that was intended for a non-ROM BAR.  We have
seen this happen during PCI hotplug of an adapter that contains a P2P
bridge where successful memory allocation for an expansion ROM BAR on
device behind the bridge consumed memory that was intended for a non-ROM
BAR on the P2P bridge.  In all cases the allocation failure messages can
be very confusing for users.

This patch addresses the issue by changing the kernel default behavior
so that expansion ROM memory allocations are no longer attempted by
default when the BIOS has not assigned a specific address range to the
expansion ROM BAR.  This was done by changing the 'pci=rom' boot option
behavior for BIOS unassigned expansion ROMs to actually match it's
current kernel-parameters.txt description which already implies "off" by
default. Behavior for BIOS assigned expansion ROMs implemented in
pcibios_assign_resources() [arch/x86/pci/i386.c] is unchanged.
Signed-off-by: NGary Hade <garyhade@us.ibm.com>
Cc: Greg KH <greg@kroah.com>
Cc: Jan Beulich <jbeulich@novell.com>
Acked-by: N"Jun'ichi Nomura" <j-nomura@ce.jp.nec.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

dmi_alloc() for CONFIG_X86_64 is defined to allocate from a static array
and it maintains a allocation index which is advanced each time allocation
is attempted - it gets incremented even if an allocation fails thereby
depriving any future request that may be small enough to be satisfied from
the array.

Fix this by first testing if allocation is going to be possible and
incrementing alloc index only then.
Signed-off-by: NParag Warudkar <parag.warudkar@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>