Signed-off-by: NDave Airlie <airlied@redhat.com>

Fixes performance drop after suspend/resume on some systems.
Signed-off-by: NDave Airlie <airlied@redhat.com>

AGP registers weren't programmed properly for r500 cards.
Signed-off-by: NDave Airlie <airlied@redhat.com>

Texture uploads could hit the blitter coordinate limit, adjust the texture
offset when uploading the pieces. Make sure to check the end address of the
upload too.
Signed-off-by: NDave Airlie <airlied@redhat.com>

This contains all the command buffer processing for the r500 cards.
It doesn't yet contain vblank support.
Signed-off-by: NDave Airlie <airlied@redhat.com>

This inits the card pipes in the kernel and lets userspace getparam
the correct setup.
Signed-off-by: NDave Airlie <airlied@redhat.com>

Cleanup do engine reset for different chip families.
Signed-off-by: NDave Airlie <airlied@redhat.com>

Signed-off-by: NDave Airlie <airlied@redhat.com>

Signed-off-by: NDave Airlie <airlied@redhat.com>

We only support RS480 (AMD based IGP) at the moment not
RS400 (Intel based IGP) ones.
Signed-off-by: NDave Airlie <airlied@redhat.com>

Signed-off-by: NDave Airlie <airlied@redhat.com>

Signed-off-by: NDave Airlie <airlied@redhat.com>

Docs state bits 4-11 maps to bits 32-39 of the 40-bit range
Signed-off-by: NDave Airlie <airlied@redhat.com>

This adds production microcode for r100->r500 from AMD.
Signed-off-by: NDave Airlie <airlied@redhat.com>

Switch to using more correct pci dma mapping interfaces.
Signed-off-by: NDave Airlie <airlied@redhat.com>

Signed-off-by: NDave Airlie <airlied@redhat.com>

This enforces us to use the drm ioctl types so read/write works correctly and not believe
what userspace tells us.

It does this hopefully without breaking the drm api.

Fixes bug from thread: BUG: unable to handle kernel NULL pointer dereference (drm_getunique)
Signed-off-by: NDave Airlie <airlied@redhat.com>

.. and a new name, courtesy of Alan.

Merge branch 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86: fix pointer type warning in arch/x86/mm/init_64.c:early_memtest
  x86, lockdep: fix "WARNING: at kernel/lockdep.c:2658 check_flags+0x4c/0x128()"
  x86: fix an incompatible pointer type warning on 64-bit compilations
  x86: fix lockdep warning during suspend-to-ram
  x86: fix unused variable 'loops' warning in arch/x86/boot/a20.c
  Revert "x86: fix ioapic bug again"
  x86: fix asm warning in head_32.S
  x86: fix endless page faults in mount_block_root for Linux 2.6
  geode: fix modular build

Merge branch 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  sched: 64-bit: fix arithmetics overflow
  sched: fair group: fix overflow(was: fix divide by zero)
  sched: fix TASK_WAKEKILL vs SIGKILL race

Changed the call to find_e820_area_size to pass u64 instead of unsigned long.
Signed-off-by: NKevin Winchester <kjwinchester@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Alessandro Suardi reported:
> Recently upgraded my FC6 desktop to Fedora 9; with the
>  latest nautilus RPM updates my VNC session went nuts
>  with nautilus pegging the CPU for everything that breathed.
>
> I now reverted to an earlier nautilus package, but during
>  the peak CPU period my kernel spat this:
>
> [314185.623294] ------------[ cut here ]------------
> [314185.623414] WARNING: at kernel/lockdep.c:2658 check_flags+0x4c/0x128()
> [314185.623514] Modules linked in: iptable_filter ip_tables x_tables
> sunrpc ipv6 fuse snd_via82xx snd_ac97_codec ac97_bus snd_mpu401_uart
> snd_rawmidi via686a hwmon parport_pc sg parport uhci_hcd ehci_hcd
> [314185.623924] Pid: 12314, comm: nautilus Not tainted 2.6.26-rc5-git2 #4
> [314185.624021]  [<c0115b95>] warn_on_slowpath+0x41/0x7b
> [314185.624021]  [<c010de70>] ? do_page_fault+0x2c1/0x5fd
> [314185.624021]  [<c0128396>] ? up_read+0x16/0x28
> [314185.624021]  [<c010de70>] ? do_page_fault+0x2c1/0x5fd
> [314185.624021]  [<c012fa33>] ? __lock_acquire+0xbb4/0xbc3
> [314185.624021]  [<c012d0a0>] check_flags+0x4c/0x128
> [314185.624021]  [<c012fa73>] lock_acquire+0x31/0x7d
> [314185.624021]  [<c0128cf6>] __atomic_notifier_call_chain+0x30/0x80
> [314185.624021]  [<c0128cc6>] ? __atomic_notifier_call_chain+0x0/0x80
> [314185.624021]  [<c0128d52>] atomic_notifier_call_chain+0xc/0xe
> [314185.624021]  [<c0128d81>] notify_die+0x2d/0x2f
> [314185.624021]  [<c01043b0>] do_int3+0x1f/0x4d
> [314185.624021]  [<c02f2d3b>] int3+0x27/0x2c
> [314185.624021]  =======================
> [314185.624021] ---[ end trace 1923f65a2d7bb246 ]---
> [314185.624021] possible reason: unannotated irqs-off.
> [314185.624021] irq event stamp: 488879
> [314185.624021] hardirqs last  enabled at (488879): [<c0102d67>]
> restore_nocheck+0x12/0x15
> [314185.624021] hardirqs last disabled at (488878): [<c0102dca>]
> work_resched+0x19/0x30
> [314185.624021] softirqs last  enabled at (488876): [<c011a1ba>]
> __do_softirq+0xa6/0xac
> [314185.624021] softirqs last disabled at (488865): [<c010476e>]
> do_softirq+0x57/0xa6
>
> I didn't seem to find it with some googling, so here it is.
>
> I was incidentally ltracing that process to try and find out
>  what was gulping down that much CPU (sorry, no idea
>  whether ltrace and the WARNING happened at the same
>  time or which came first) and:

Yeah, this is extremely likely to be the source of the warning.

The warning should be harmless, however.

> Box is my trusty noname K7-800, 512MB RAM; if there's
>  anything else useful I might be able to provide, just ask.

It would be interesting to see where the int3 comes from.  Too bad,
lockdep doesn't provide the register dump. The stacktrace also doesn't
go further than the int3(), I wonder if this int3 came from userspace?
The ltrace readme says "software breakpoints, like gdb", so I guess
this is the case. Yep, seems like it.

This looks relevant:

| commit fb1dac90
| Author: Peter Zijlstra <a.p.zijlstra@chello.nl>
| Date:   Wed Jan 16 09:51:59 2008 +0100
|
|     lockdep: more hardirq annotations for notify_die()

I'm attaching a similarly-looking patch for this case (DO_VM86_ERROR),
though I suspect it might be missing for the other cases
(DO_ERROR/DO_ERROR_INFO) as well.
Reported-by: NAlessandro Suardi <alessandro.suardi@gmail.com>
Signed-off-by: NVegard Nossum <vegard.nossum@gmail.com>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Fix an incompatible pointer type warning on x86_64 compilations.
early_memtest() is passing a u64* to find_e820_area_size() which is expecting
an unsigned long.  Change t_start and t_size to unsigned long as those are
also 64-bit types on x88_64.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Andrew Morton wrote:

> I've been seeing the below for a long time during suspend-to-ram on the Vaio.
>
>
> PM: Syncing filesystems ... done.
> PM: Preparing system for mem sleep
> Freezing user space processes ... <4>------------[ cut here ]------------
> WARNING: at kernel/lockdep.c:2658 check_flags+0x4c/0x127()
> Modules linked in: i915 drm ipw2200 sonypi ipv6 autofs4 hidp l2cap bluetooth sunrpc nf_conntrack_netbios_ns ipt_REJECT nf_conntrack_ipv4 xt_state nf_conntrack xt_tcpudp iptable_filter ip_tables x_tables acpi_cpufreq nvram ohci1394 ieee1394 ehci_hcd uhci_hcd sg joydev snd_hda_intel snd_seq_dummy sr_mod snd_seq_oss cdrom snd_seq_midi_event snd_seq snd_seq_device snd_pcm_oss snd_mixer_oss ieee80211 pcspkr ieee80211_crypt snd_pcm i2c_i801 snd_timer i2c_core ide_pci_generic piix snd soundcore snd_page_alloc button ext3 jbd ide_disk ide_core [last unloaded: ipw2200]
> Pid: 3250, comm: zsh Not tainted 2.6.26-rc5 #1
>  [<c011c5f5>] warn_on_slowpath+0x41/0x6d
>  [<c01080e6>] ? native_sched_clock+0x82/0x96
>  [<c013789c>] ? mark_held_locks+0x41/0x5c
>  [<c0315688>] ? _spin_unlock_irqrestore+0x36/0x58
>  [<c0137a29>] ? trace_hardirqs_on+0xe6/0x10d
>  [<c0138637>] ? __lock_acquire+0xae3/0xb2b
>  [<c0313413>] ? schedule+0x39b/0x3b4
>  [<c0135596>] check_flags+0x4c/0x127
>  [<c01386b9>] lock_acquire+0x3a/0x86
>  [<c0315075>] _spin_lock+0x26/0x53
>  [<c0140660>] ? refrigerator+0x13/0xc3
>  [<c0140660>] refrigerator+0x13/0xc3
>  [<c012684a>] get_signal_to_deliver+0x3c/0x31e
>  [<c0102fe7>] do_notify_resume+0x91/0x6ee
>  [<c01359fd>] ? lock_release_holdtime+0x50/0x56
>  [<c0315688>] ? _spin_unlock_irqrestore+0x36/0x58
>  [<c0235d24>] ? read_chan+0x0/0x58c
>  [<c0137a29>] ? trace_hardirqs_on+0xe6/0x10d
>  [<c0315694>] ? _spin_unlock_irqrestore+0x42/0x58
>  [<c0230afa>] ? tty_ldisc_deref+0x5c/0x63
>  [<c0233104>] ? tty_read+0x66/0x98
>  [<c014b3f0>] ? audit_syscall_exit+0x2aa/0x2c5
>  [<c0109430>] ? do_syscall_trace+0x6b/0x16f
>  [<c0103a9c>] work_notifysig+0x13/0x1b
>  =======================
> ---[ end trace 25b49fe59a25afa5 ]---
> possible reason: unannotated irqs-off.
> irq event stamp: 58919
> hardirqs last  enabled at (58919): [<c0103afd>] syscall_exit_work+0x11/0x26

Joy - I so love entry.S

Best I can make of it:

syscall_exit_work
  resume_userspace
    DISABLE_INTERRUPTS
    (no TRACE_IRQS_OFF)
      work_pending
        work_notifysig
          do_notify_resume()
            do_signal()
              get_signal_to_deliver()
                try_to_freeze()
                  refrigerator()
                    task_lock() -> check_flags() -> BANG

The normal path is:

syscall_exit_work
  resume_userspace
    DISABLE_INTERRUPTS
    restore_all
      TRACE_IRQS_IRET
      iret

No idea why that would not warn..
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Following patch fixes the below warning message :
arch/x86/boot/a20.c:118: warning: unused variable 'loops'

Signed-off-by : Manish Katiyar <mkatiyar@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

This reverts commit 6e908947.

Németh Márton reported:

| there is a problem in 2.6.26-rc3 which was not there in case of
| 2.6.25: the CPU wakes up ~90,000 times per sec instead of ~60 per sec.
|
| I also "git bisected" the problem, the result is:
|
| 6e908947 is first bad commit
| commit 6e908947
| Author: Ingo Molnar <mingo@elte.hu>
| Date:   Fri Mar 21 14:32:36 2008 +0100
|
|     x86: fix ioapic bug again

the original problem is fixed by Maciej W. Rozycki in the tip/x86/apic
branch (confirmed by Márton), but those changes are too intrusive for
v2.6.26 so we'll go for the less intrusive (repeated) revert now.
Reported-and-bisected-by: NNémeth Márton <nm127@freemail.hu>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

On Mon, May 19, 2008 at 04:10:02PM -0700, Linus Torvalds wrote:
> It also causes these warnings on 32-bit PAE:
>
> 	  AS      arch/x86/kernel/head_32.o
> 	arch/x86/kernel/head_32.S: Assembler messages:
> 	arch/x86/kernel/head_32.S:225: Warning: left operand is a bignum; integer 0 assumed
> 	arch/x86/kernel/head_32.S:609: Warning: left operand is a bignum; integer 0 assumed
>
> and I do not see why (the end result seems to be identical).

Fix head_32.S gcc bignum warnings when CONFIG_PAE=y.

    arch/x86/kernel/head_32.S: Assembler messages:
    arch/x86/kernel/head_32.S:225: Warning: left operand is a bignum; integer 0 assumed
    arch/x86/kernel/head_32.S:609: Warning: left operand is a bignum; integer 0 assumed

The assembler was stumbling over the 64-bit constant 0x100000000 in the
KPMDS #define.

Testing: a cmp(1) on head_32.o before and after shows the binary is unchanged.

Signed-off-by: Joe Korty <joe.korty@ccur.com
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Theodore Tso <tytso@mit.edu>
Cc: Gabriel C <nix.or.die@googlemail.com>
Cc: Keith Packard <keithp@keithp.com>
Cc: "Pallipadi Venkatesh" <venkatesh.pallipadi@intel.com>
Cc: Eric Anholt <eric@anholt.net>
Cc: "Siddha Suresh B" <suresh.b.siddha@intel.com>
Cc: bugme-daemon@bugzilla.kernel.org
Cc: airlied@linux.ie
Cc: "Barnes Jesse" <jesse.barnes@intel.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Page faults in kernel address space between PAGE_OFFSET up to
VMALLOC_START should not try to map as vmalloc.

Fix rarely endless page faults inside mount_block_root for root
filesystem at boot time.

All 32bit kernels up to 2.6.25 can fail into this hole.
I can not present this under native linux kernel. I see, that the 64bit
has fixed the problem. I copied the same lines into 32bit part.

Recorded debugs are from coLinux kernel 2.6.22.18 (virtualisation):
http://www.henrynestler.com/colinux/testing/pfn-check-0.7.3/20080410-antinx/bug16-recursive-page-fault-endless.txt
The physicaly memory was trimmed down to 192MB to better catch the bug.
More memory gets the bug more rarely.

Details, how every x86 32bit system can fail:

Start from "mount_block_root",
http://lxr.linux.no/linux/init/do_mounts.c#L297
There the variable "fs_names" got one memory page with 4096 bytes.
Variable "p" walks through the existing file system types. The first
string is no problem.
But, with the second loop in mount_block_root the offset of "p" is not
at beginning of page, the offset is for example +9, if "reiserfs" is the
first in list.
Than calls do_mount_root, and lands in sys_mount.
Remember: Variable "type_page" contains now "fs_type+9" and not contains
a full page.
The sys_mount copies 4096 bytes with function "exact_copy_from_user()":
http://lxr.linux.no/linux/fs/namespace.c#L1540

Mostly exist pages after the buffer "fs_names+4096+9" and the page fault
handler was not called. No problem.

In the case, if the page after "fs_names+4096" is not mapped, the page
fault handler was called from http://lxr.linux.no/linux/fs/namespace.c#L1320

The do_page_fault gots an address 0xc03b4000.
It's kernel address, address >= TASK_SIZE, but not from vmalloc! It's
from "__getname()" alias "kmem_cache_alloc".
The "error_code" is 0. "vmalloc_fault" will be call:
http://lxr.linux.no/linux/arch/i386/mm/fault.c#L332

"vmalloc_fault" tryed to find the physical page for a non existing
virtual memory area. The macro "pte_present" in vmalloc_fault()
got a next page fault for 0xc0000ed0 at:
http://lxr.linux.no/linux/arch/i386/mm/fault.c#L282

No PTE exist for such virtual address. The page fault handler was trying
to sync the physical page for the PTE lockup.

This called vmalloc_fault() again for address 0xc000000, and that also
was not existing. The endless began...

In normal case the cpu would still loop with disabled interrrupts. Under
coLinux this was catched by a stack overflow inside printk debugs.
Signed-off-by: NHenry Nestler <henry.nestler@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

-tip testing found this build bug:

 MODPOST 331 modules
 ERROR: "geode_mfgpt_toggle_event" [drivers/watchdog/geodewdt.ko] undefined!
 ERROR: "geode_mfgpt_alloc_timer" [drivers/watchdog/geodewdt.ko] undefined!
 make[1]: *** [__modpost] Error 1
 make: *** [modules] Error 2

with this config:

  http://redhat.com/~mingo/misc/config-Wed_Jun__4_18_01_59_CEST_2008.bad

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

As we may run relay_reserve from interrupt context we must always disable
IRQs.  This is because a call to relay_reserve may expose previously written
data to use space.

Updated new message code and an old but related comment.
Signed-off-by: NCarl Henrik Lunde <chlunde@ping.uio.no>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

* git://git.kernel.org/pub/scm/linux/kernel/git/sam/kbuild-fixes:
  kbuild: ignore powerpc specific symbols in modpost

This implements a few changes on top of the recent kobjsize() refactoring
introduced by commit 6cfd53fc.

As Christoph points out:

	virt_to_head_page cannot return NULL. virt_to_page also
	does not return NULL. pfn_valid() needs to be used to
	figure out if a page is valid.  Otherwise the page struct
	reference that was returned may have PageReserved() set
	to indicate that it is not a valid page.

As discussed further in the thread, virt_addr_valid() is the preferable
way to validate the object pointer in this case. In addition to fixing
up the reserved page case, it also has the benefit of encapsulating the
hack introduced by commit 4016a139 on
the impacted platforms, allowing us to get rid of the extra checking in
kobjsize() for the platforms that don't perform this type of bizarre
memory_end abuse (every nommu platform that isn't blackfin). If blackfin
decides to get in line with every other platform and use PageReserved
for the DMA pages in question, kobjsize() will also continue to work
fine.

It also turns out that compound_order() will give us back 0-order for
non-head pages, so we can get rid of the PageCompound check and just
use compound_order() directly. Clean that up while we're at it.
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>
Reviewed-by: NChristoph Lameter <clameter@sgi.com>
Acked-by: NDavid Howells <dhowells@redhat.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This patch fixes a compile failure in 2.6.26-rc5-git5.

The variable is expected to be called ofdev.
Signed-off-by: NJeff Mahoney <jeffm@suse.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

* 'core/iter-div' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  always_inline timespec_add_ns
  add an inlined version of iter_div_u64_rem
  common implementation of iterative div/mod

Kumar Gala <galak@kernel.crashing.org> wrote:
We have a case in powerpc in which we want to link some library
routines with all module objects.  The routines are intended for
handling out-of-line function call register save/restore so having
them as EXPORT_SYMBOL() is counter productive (we do also need to
link the same "library" code into the kernel).

Without this patch a powerpc build would error out and fail
to build modules with the added register save/restore module.

There were two obvious solutions:
1) To link the .o file before the modpost stage
2) To ignore the symbols in modpost

Option 1) was ruled out because we do not have any separate
linking stage for single file modules.

This patch implements option 2 - and do so only for powerpc.

The symbols we ignore are all undefined symbols named:
_restgpr_*, _savegpr_*, _rest32gpr_*, _save32gpr_*
Signed-off-by: NSam Ravnborg <sam@ravnborg.org>
Cc: Kumar Gala <galak@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>

(overflow means weight >= 2^32 here, because inv_weigh = 2^32/weight)

A weight of a cfs_rq is the sum of weights of which entities
are queued on this cfs_rq, so it will overflow when there are
too many entities.

Although, overflow occurs very rarely, but it break fairness when
it occurs. 64-bits systems have more memory than 32-bit systems
and 64-bit systems can create more process usually, so overflow may
occur more frequently.

This patch guarantees fairness when overflow happens on 64-bit systems.
Thanks to the optimization of compiler, it changes nothing on 32-bit.
Signed-off-by: NLai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

I found a bug which can be reproduced by this way:(linux-2.6.26-rc5, x86-64)
(use 2^32, 2^33, ...., 2^63 as shares value)

# mkdir /dev/cpuctl
# mount -t cgroup -o cpu cpuctl /dev/cpuctl
# cd /dev/cpuctl
# mkdir sub
# echo 0x8000000000000000 > sub/cpu.shares
# echo $$ > sub/tasks
oops here! divide by zero.

This is because do_div() expects the 2th parameter to be 32 bits,
but unsigned long is 64 bits in x86_64.

Peter Zijstra pointed it out that the sane thing to do is limit the
shares value to something smaller instead of using an even more
expensive divide.

Also, I found another bug about "the shares value is too large":

pid1 and pid2 are set affinity to cpu#0
pid1 is attached to cg1 and pid2 is attached to cg2

if cg1/cpu.shares = 1024 cg2/cpu.shares = 2000000000
then pid2 got 100% usage of cpu, and pid1 0%

if cg1/cpu.shares = 1024 cg2/cpu.shares = 20000000000
then pid2 got 0% usage of cpu, and pid1 100%

And a weight of a cfs_rq is the sum of weights of which entities
are queued on this cfs_rq, so the shares value should be limited
to a smaller value.

I think that (1UL << 18) is a good limited value:

1) it's not too large, we can create a lot of group before overflow
2) it's several times the weight value for nice=-19 (not too small)
Signed-off-by: NLai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

timespec_add_ns is used from the x86-64 vdso, which cannot call out to
other kernel code.  Make sure that timespec_add_ns is always inlined
(and only uses always_inlined functions) to make sure there are no
unexpected calls.
Signed-off-by: NJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

iter_div_u64_rem is used in the x86-64 vdso, which cannot call other
kernel code.  For this case, provide the always_inlined version,
__iter_div_u64_rem.
Signed-off-by: NJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

We have a few instances of the open-coded iterative div/mod loop, used
when we don't expcet the dividend to be much bigger than the divisor.
Unfortunately modern gcc's have the tendency to strength "reduce" this
into a full mod operation, which isn't necessarily any faster, and
even if it were, doesn't exist if gcc implements it in libgcc.

The workaround is to put a dummy asm statement in the loop to prevent
gcc from performing the transformation.

This patch creates a single implementation of this loop, and uses it
to replace the open-coded versions I know about.
Signed-off-by: NJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Segher Boessenkool <segher@kernel.crashing.org>
Cc: Christian Kujau <lists@nerdbynature.de>
Cc: Robert Hancock <hancockr@shaw.ca>
Signed-off-by: NIngo Molnar <mingo@elte.hu>