Clean up a few different parts of omap_set_pwrdm_state():

- Remove a superfluous call to pwrdm_state_switch().  Not needed
  unless LOWPOWERSTATECHANGE is used, because the state switch code is
  called by either clkdm_sleep() or clkdm_allow_idle().

- Add code to wait for the power state transition in the OMAP4+ low
  power state change.  This is speculative, so I would particularly
  appreciate feedback on this part.

- Remove a superfluous call to pwrdm_read_pwrst().

- Update variable names to be more meaningful (hopefully) and precise.

- Fix an error path bug that would not place the clockdomain back into
  hardware-supervised idle or sleep mode if the power state could not
  be programmed.

The documentation for this function still needs major improvements;
that's left for a later patch.
Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Rajendra Nayak <rnayak@ti.com>
Tested-by: Tero Kristo <t-kristo@ti.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Tested-by: Kevin Hilman <khilman@ti.com>
Signed-off-by: Kevin Hilman <khilman@ti.com>

Remove some superfluous calls to pwrdm_clear_all_prev_pwrst().
pwrdm_pre_transition(), which appears a few lines after these calls,
invokes pwrdm_clear_all_prev_pwrst() on each powerdomain -- there's no
need to do it twice.

N.B.: some of us have observed that accesses to the previous
powerstate registers seem to be quite slow.  Although the writes
removed by this patch should be buffered by the write buffer, there is
a read to a PRM register immediately afterwards.  That will block the
OMAP3 MPU until all of those writes complete.  So this patch should
result in a minor performance improvement during idle entry.
Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Rajendra Nayak <rnayak@ti.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Tested-by: Tero Kristo <t-kristo@ti.com>
[khilman@ti.com: removed a couple more for OMAP4]
Tested-by: Kevin Hilman <khilman@ti.com>
Signed-off-by: Kevin Hilman <khilman@ti.com>

With the introduction of iomap changes platform init code
fails for emu.c if CONFIG_OMAP3_EMU is selected:

arch/arm/mach-omap2/emu.c:35:8: error:
'L4_EMU_34XX_BASE' undeclared here (not in a function)
Signed-off-by: Tony Lindgren <tony@atomide.com>

Building omap_devices should only be done at init time, and since
omap_device_build() is using early_platform calls which are also
__init, this ensures that omap_device isn't trying to use functions
that disappear.
Signed-off-by: Kevin Hilman <khilman@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

Now that omap hsmmc init is split into two functions, it's safe
to mark omap_hsmmc_init and omap_mux related functions to __init.

This basically reverts the following fixes for the case where
TWL was compiled as a module:

a98f77bb (ARM: omap: fix section mismatch warning for sdp3430_twl_gpio_setup())
8930b4e3 (ARM: omap: fix section mismatch warnings in mux.c caused by hsmmc.c)

Additionally it fixes up the remaining section warnings for
all callers of omap_mux functions.

Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Tony Lindgren <tony@atomide.com>

Drivers should no longer use omap_read/write functions
but instead use ioremap + read/write functions.

As some USB legacy code is still shared between omap1 and
omap2420, let's limit the omap_read/write to plat/usb.h.

Note that the long term fix is to update the drivers to
use ioremap and read/write functions. That can now be
done as a separate patch series that is limited to the
USB drivers.

Also make sure the legacy omap1-keypad.c driver builds
if selected for 2420 based systems.

Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

This is needed to minimize io.h so the SoC specific io.h
for ARMs can removed.

Note that minimal driver changes for DSS and RNG are needed to
include cpu.h for SoC detection macros.

Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Tony Lindgren <tony@atomide.com>

There's no need to have these defines in plat/io.h.

Note that we now need to ifdef omap_read/write calls
as they will be available for omap1 only.

While at it, clean up the includes to group them like
they typically are grouped.
Signed-off-by: Tony Lindgren <tony@atomide.com>

There's no need to have these in plat/io.h.

While at it, clean up the includes to group them
like they typically are grouped.
Signed-off-by: Tony Lindgren <tony@atomide.com>

This way we can remove omap_read/write call from the GPIO driver
and remove include to linux/io.h.

Cc: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Tony Lindgren <tony@atomide.com>

We don't want to keep it in io.h as we want to remove io.h
for omap2+ for the common zImage support.
Signed-off-by: Tony Lindgren <tony@atomide.com>

These should be local to omap2/3/4.
Signed-off-by: Tony Lindgren <tony@atomide.com>

This is only needed when using SRAM for framebuffer,
and the support for SRAM framebuffer is about to get
removed.

Otherwise we cannot move most of plat/io.h to be a local
iomap.h for mach-omap2.

Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: linux-fbdev@vger.kernel.org
Signed-off-by: Tony Lindgren <tony@atomide.com>

Remove omap_{read,write}l() from the 24xx PM code.  The clocksource
code should now handle what this was supposed to do.

Tested on N800 -- but it's hard to say whether this fixes anything.
OMAP24xx static suspend path is currently broken, and this patch
doesn't change that.
Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Rob Herring <robherring2@gmail.com>
Acked-by: Kevin Hilman <khilman@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

Flag single_channel in struct omap2_mcspi_device_config is not used
by drivers/spi/spi-omap2-mcspi.c so we may remove it from include/plat/mcspi.h
and affected board files.
Signed-off-by: Jarkko Nikula <jarkko.nikula@bitmer.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

Now that most platforms don't need disable_fiq and arch_ret_to_user
macros, we can remove the empty macros or empty entry-macro.S files.
Signed-off-by: Rob Herring <rob.herring@calxeda.com>
Acked-by: Jamie Iles <jamie@jamieiles.com>
Acked-by: Nicolas Pitre <nico@linaro.org>
Acked-by: Tony Lindgren <tony@atomide.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Ryan Mallon <rmallon@gmail.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Acked-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Acked-by: Shawn Guo <shawn.guo@linaro.org>

With the removal of disable_fiq on rpc and addition MULTI_IRQ_HANDLER,
entry-macro.S is no longer needed for platforms that select
MULTI_IRQ_HANDLER and the include of it can be conditional.
Signed-off-by: Rob Herring <rob.herring@calxeda.com>
Acked-by: Nicolas Pitre <nico@linaro.org>
Acked-by: H Hartley Sweeten <hsweeten@visionengravers.com>

Only rpc uses disable_fiq macro. Change it to a run-time installed
default FIQ handler. The handler is installed before FIQ is enabled
so the behavior should be unchanged.
Signed-off-by: Rob Herring <rob.herring@calxeda.com>
Acked-by: Nicolas Pitre <nico@linaro.org>

Only 3 platforms need arch_ret_to_user macro, so add ARCH_HAS_RET_TO_USER
kconfig option and make iop13xx, iop32x and iop33x select it.
Signed-off-by: Rob Herring <rob.herring@calxeda.com>
Acked-by: Nicolas Pitre <nico@linaro.org>

Otherwise omap_device_build() and omap_mux related functions
can't be marked as __init when twl is build as a module.

If a board is using GPIO pins or regulators configured by an
external chip, such as TWL PMIC on I2C bus, the board must
mark those MMC controllers as deferred. Additionally both
omap_hsmmc_init() and omap_hsmmc_late_init() must be called
by the board.

For MMC controllers using internal GPIO pins for card
detect and regulators the slots don't need to be marked
deferred. In this case calling omap_hsmmc_init() is sufficient.

Only mark the MMC slots using gpio_cd or gpio_wd as deferred
as noted by Igor Grinberg <grinberg@compulab.co.il>.

Note that this patch does not change the behaviour for
board-4430sdp.c board-omap4panda.c. These boards wrongly
rely on the omap_hsmmc.c init function callback to configure
the PMIC GPIO interrupt lines on external chip. If the PMIC
interrupt lines are not configured during init, they will
fail.
Reported-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Rajendra Nayak <rnayak@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

Expose omap_device_{alloc, delete, register} so we can use them outside
of omap_device.c.

This approach allows users, which need to manipulate an archdata member
of a device before it is registered, to do so. This is also useful
for users who have their devices created very early so they can be used
at ->reserve() time to reserve CMA memory.

The immediate use case for this is to set the private iommu archdata
member, which binds a device to its associated iommu controller.
This way, generic code will be able to attach omap devices to their
iommus, without calling any omap-specific API.

With this in hand, we can further clean the existing mainline OMAP iommu
driver and its mainline users, and focus on generic IOMMU approaches
for future users (rpmsg/remoteproc and the upcoming generic DMA API).

This patch is still considered an interim solution until DT fully materializes
for omap; at that point, this functionality will be removed as DT will
take care of creating the devices and configuring them correctly.

Tested on OMAP4 with a generic rpmsg/remoteproc that doesn't use any
omap-specific IOMMU API anymore.
Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>
Signed-off-by: Kevin Hilman <khilman@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

Otherwise we get the following error:

arch/arm/mach-omap2/built-in.o: In function `n8x0_mmc_callback':
twl-common.c:(.text+0x108a0): undefined reference to
`omap_mmc_notify_cover_event'

Fix this by warning about unusable MMC cover events.

The long term fix needs to change the MMC drivers to
register board specific callbacks directly with PMIC.
Reported-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Tony Lindgren <tony@atomide.com>

On some omaps twl4030_gpio has a callback to try to initialize
the MMC controller. If twl4030_gpio is compiled as a module,
bad things can happen because the callback function starts
calling functions that are supposed to be marked __init:

Kernel panic - not syncing: Attempted to kill the idle task!
twl4030_gpio twl4030_gpio: can't dispatch IRQs from modules
gpiochip_add: registered GPIOs 192 to 209 on device: twl4030
Unable to handle kernel paging request at virtual address b82a4c74
...

Additionally if this does not fail, warnings are produced
about trying to register the MMC multiple times.

Fix this by removing __init from omap_mux_get_by_name,
and add checks if omap2_hsmmc_init() is getting called more
than once.

Note that this will get fixed properly later on by splitting
omap2_hsmmc_init into two functions.
Reported-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Tony Lindgren <tony@atomide.com>

These are the bug fixes that have accumulated since 3.3-rc3 in arm-soc.
The majority of them are regression fixes for stuff that broke during
the merge 3.3 window.

The notable ones are:

* The at91 ata drivers both broke because of an earlier cleanup patch that
  some other patches were based on. Jean-Christophe decided to remove
  the legacy at91_ide driver and fix the new-style at91-pata driver while
  keeping the cleanup patch. I almost rejected the patches for being too
  late and too big but in the end decided to accept them because they
  fix a regression.

* A patch fixing build breakage from the sysdev-to-device conversion
  colliding with other changes touches a number of mach-s3c files.

* b0654037 "ARM: orion: Fix Orion5x GPIO regression from MPP cleanup"
  is a mechanical change that unfortunately touches a lot of lines
  that should up in the diffstat.

* tag 'fixes-3.3-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc: (28 commits)
  ARM: at91: drop ide driver in favor of the pata one
  pata/at91: use newly introduced SMC accessors
  ARM: at91: add accessor to manage SMC
  ARM: at91:rtc/rtc-at91sam9: ioremap register bank
  ARM: at91: USB AT91 gadget registration for module
  ep93xx: fix build of vision_ep93xx.c
  ARM: OMAP2xxx: PM: fix OMAP2xxx-specific UART idle bug in v3.3
  ARM: orion: Fix USB phy for orion5x.
  ARM: orion: Fix Orion5x GPIO regression from MPP cleanup
  ARM: EXYNOS: Add cpu-offset property in gic device tree node
  ARM: EXYNOS: Bring exynos4-dt up to date
  ARM: OMAP3: cm-t35: fix section mismatch warning
  ARM: OMAP2: Fix the OMAP2 only build break seen with 2011+ ARM tool-chains
  ARM: tegra: paz00: fix wrong UART port on mini-pcie plug
  ARM: tegra: paz00: fix wrong SD1 power gpio
  i2c: tegra: Add devexit_p() for remove
  ARM: EXYNOS: Correct M-5MOLS sensor clock frequency on Universal C210 board
  ARM: EXYNOS: Correct framebuffer window size on Nuri board
  ARM: SAMSUNG: Fix missing api-change from subsys_interface change
  ARM: EXYNOS: Fix "warning: initialization from incompatible pointer type"
  ...

1) VETH_INFO_PEER netlink attribute needs to have it's size validated,
   from Thomas Graf.

2) 'poll' module option of bnx2x driver crashes the machine, just remove
   it.  From Michal Schmidt.

3) ks8851_mll driver reads the irq number from two places, but only
   initializes one of them, oops.  Use only one location and fix this
   problem, from Jan Weitzel.

4) Fix buffer overrun and unicast sterring bugs in mellanox mlx4 driver,
   from Eugenia Emantayev.

5) Swapped kcalloc() args in RxRPC and mlx4, from Axel Lin.

6) PHY MDIO device name regression fixes from Florian Fainelli.

7) If the wake event IRQ line is different from the netdevice one, we
   have to properly route it to the stmmac interrupt handler.  From
   Francesco Virlinzi.

8) Fix rwlock lock initialization ordering bug in mac80211, from
   Mohammed Shafi Shajakhan.

9) TCP lost_cnt can get out of sync, and in fact go negative, in certain
   circumstances.  Fix the way we specify what sequence range to operate
   on in tcp_sacktag_one() to fix this bug.  From Neal Cardwell.

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (27 commits)
  net/ethernet: ks8851_mll fix irq handling
  veth: Enforce minimum size of VETH_INFO_PEER
  stmmac: update the driver version to Feb 2012 (v2)
  stmmac: move hw init in the probe (v2)
  stmmac: request_irq when use an ext wake irq line (v2)
  stmmac: do not discard frame on dribbling bit assert
  ipheth: Add iPhone 4S
  mlx4: add unicast steering entries to resource_tracker
  mlx4: fix QP tree trashing
  mlx4: fix buffer overrun
  3c59x: shorten timer period for slave devices
  netpoll: netpoll_poll_dev() should access dev->flags
  RxRPC: Fix kcalloc parameters swapped
  bnx2x: remove the 'poll' module option
  tcp: fix tcp_shifted_skb() adjustment of lost_cnt_hint for FACK
  ks8851: Fix NOHZ local_softirq_pending 08 warning
  bnx2x: fix bnx2x_storm_stats_update() on big endian
  ixp4xx-eth: fix PHY name to match MDIO bus name
  octeon: fix PHY name to match MDIO bus name
  fec: fix PHY name to match fixed MDIO bus name
  ...

Fixes a bootstrapping issue for some registers when a less commonly used
method for register cache initialisation is used.  Only affects a fairly
small proportion of users that both don't use explicit register defaults
and do use the cache.

* tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regmap:
  regmap: Fix cache defaults initialization from raw cache defaults

Merge tag 'ecryptfs-3.3-rc4-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tyhicks/ecryptfs

Fixes maximum filename length and filesystem type reporting in statfs() calls
and also fixes stale inode mode bits on eCryptfs inodes after a POSIX ACL was
set on the lower filesystem's inode.

* tag 'ecryptfs-3.3-rc4-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tyhicks/ecryptfs:
  ecryptfs: remove the second argument of k[un]map_atomic()
  eCryptfs: Copy up lower inode attrs after setting lower xattr
  eCryptfs: Improve statfs reporting

pinctrl fixes for v3.3

* tag 'pinctrl-for-torvalds-20120216' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl:
  pinctrl: restore pin naming

Here are a few more fixes for powerpc.  Some are regressions, the rest
is simple/obvious/nasty enough that I deemed it good to go now.

Here's also step one of deprecating legacy iSeries support: we are
removing it from the main defconfig.

Nobody seems to be using it anymore and the code is nasty to maintain,
(involves horrible hacks in various low level areas of the kernel) so we
plan to actually rip it out at some point.  For now let's just avoid
building it by default.  Stephen will proceed to do the actual removal
later (probably 3.4 or 3.5).

* 'merge' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc:
  powerpc/perf: power_pmu_start restores incorrect values, breaking frequency events
  powerpc/adb: Use set_current_state()
  powerpc: Disable interrupts early in Program Check
  powerpc: Remove legacy iSeries from ppc64_defconfig
  powerpc/fsl/pci: Fix PCIe fixup regression
  powerpc: Fix kernel log of oops/panic instruction dump

One regression fix for SR-IOV on PPC and a couple of misc fixes from
Yinghai.

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jbarnes/pci:
  PCI: Fix pci cardbus removal
  PCI: set pci sriov page size before reading SRIOV BAR
  PCI: workaround hard-wired bus number V2

3 radeon fixes, I have some exynos fixes to push later but I'll queue
them separately once I've looked them over a bit.

* 'drm-fixes' of git://people.freedesktop.org/~airlied/linux:
  drm/radeon/kms: fix MSI re-arm on rv370+
  drm/radeon/kms/atom: bios scratch reg handling updates
  drm/radeon/kms: drop lock in return path of radeon_fence_count_emitted.

* git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6:
  crypto: sha512 - use standard ror64()

After all the FPU state cleanups and finally finding the problem that
caused all our FPU save/restore problems, this re-introduces the
preloading of FPU state that was removed in commit b3b0870e ("i387:
do not preload FPU state at task switch time").

However, instead of simply reverting the removal, this reimplements
preloading with several fixes, most notably

 - properly abstracted as a true FPU state switch, rather than as
   open-coded save and restore with various hacks.

   In particular, implementing it as a proper FPU state switch allows us
   to optimize the CR0.TS flag accesses: there is no reason to set the
   TS bit only to then almost immediately clear it again.  CR0 accesses
   are quite slow and expensive, don't flip the bit back and forth for
   no good reason.

 - Make sure that the same model works for both x86-32 and x86-64, so
   that there are no gratuitous differences between the two due to the
   way they save and restore segment state differently due to
   architectural differences that really don't matter to the FPU state.

 - Avoid exposing the "preload" state to the context switch routines,
   and in particular allow the concept of lazy state restore: if nothing
   else has used the FPU in the meantime, and the process is still on
   the same CPU, we can avoid restoring state from memory entirely, just
   re-expose the state that is still in the FPU unit.

   That optimized lazy restore isn't actually implemented here, but the
   infrastructure is set up for it.  Of course, older CPU's that use
   'fnsave' to save the state cannot take advantage of this, since the
   state saving also trashes the state.

In other words, there is now an actual _design_ to the FPU state saving,
rather than just random historical baggage.  Hopefully it's easier to
follow as a result.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

This moves the bit that indicates whether a thread has ownership of the
FPU from the TS_USEDFPU bit in thread_info->status to a word of its own
(called 'has_fpu') in task_struct->thread.has_fpu.

This fixes two independent bugs at the same time:

 - changing 'thread_info->status' from the scheduler causes nasty
   problems for the other users of that variable, since it is defined to
   be thread-synchronous (that's what the "TS_" part of the naming was
   supposed to indicate).

   So perfectly valid code could (and did) do

	ti->status |= TS_RESTORE_SIGMASK;

   and the compiler was free to do that as separate load, or and store
   instructions.  Which can cause problems with preemption, since a task
   switch could happen in between, and change the TS_USEDFPU bit. The
   change to TS_USEDFPU would be overwritten by the final store.

   In practice, this seldom happened, though, because the 'status' field
   was seldom used more than once, so gcc would generally tend to
   generate code that used a read-modify-write instruction and thus
   happened to avoid this problem - RMW instructions are naturally low
   fat and preemption-safe.

 - On x86-32, the current_thread_info() pointer would, during interrupts
   and softirqs, point to a *copy* of the real thread_info, because
   x86-32 uses %esp to calculate the thread_info address, and thus the
   separate irq (and softirq) stacks would cause these kinds of odd
   thread_info copy aliases.

   This is normally not a problem, since interrupts aren't supposed to
   look at thread information anyway (what thread is running at
   interrupt time really isn't very well-defined), but it confused the
   heck out of irq_fpu_usable() and the code that tried to squirrel
   away the FPU state.

   (It also caused untold confusion for us poor kernel developers).

It also turns out that using 'task_struct' is actually much more natural
for most of the call sites that care about the FPU state, since they
tend to work with the task struct for other reasons anyway (ie
scheduling).  And the FPU data that we are going to save/restore is
found there too.

Thanks to Arjan Van De Ven <arjan@linux.intel.com> for pointing us to
the %esp issue.

Cc: Arjan van de Ven <arjan@linux.intel.com>
Reported-and-tested-by: Raphael Prevost <raphael@buro.asia>
Acked-and-tested-by: Suresh Siddha <suresh.b.siddha@intel.com>
Tested-by: Peter Anvin <hpa@zytor.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The AMD K7/K8 CPUs don't save/restore FDP/FIP/FOP unless an exception is
pending.  In order to not leak FIP state from one process to another, we
need to do a floating point load after the fxsave of the old process,
and before the fxrstor of the new FPU state.  That resets the state to
the (uninteresting) kernel load, rather than some potentially sensitive
user information.

We used to do this directly after the FPU state save, but that is
actually very inconvenient, since it

 (a) corrupts what is potentially perfectly good FPU state that we might
     want to lazy avoid restoring later and

 (b) on x86-64 it resulted in a very annoying ordering constraint, where
     "__unlazy_fpu()" in the task switch needs to be delayed until after
     the DS segment has been reloaded just to get the new DS value.

Coupling it to the fxrstor instead of the fxsave automatically avoids
both of these issues, and also ensures that we only do it when actually
necessary (the FP state after a save may never actually get used).  It's
simply a much more natural place for the leaked state cleanup.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Yes, taking the trap to re-load the FPU/MMX state is expensive, but so
is spending several days looking for a bug in the state save/restore
code.  And the preload code has some rather subtle interactions with
both paravirtualization support and segment state restore, so it's not
nearly as simple as it should be.

Also, now that we no longer necessarily depend on a single bit (ie
TS_USEDFPU) for keeping track of the state of the FPU, we migth be able
to do better.  If we are really switching between two processes that
keep touching the FP state, save/restore is inevitable, but in the case
of having one process that does most of the FPU usage, we may actually
be able to do much better than the preloading.

In particular, we may be able to keep track of which CPU the process ran
on last, and also per CPU keep track of which process' FP state that CPU
has.  For modern CPU's that don't destroy the FPU contents on save time,
that would allow us to do a lazy restore by just re-enabling the
existing FPU state - with no restore cost at all!
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>