inverted logic.
Noticed-by: NSylvain BERTRAND <sylware@legeek.net>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

The CP semaphore queue on CIK has a bug that triggers if uncompleted
waits use the same address while a signal is still pending. Work around
this by using different addresses for each sync.
Signed-off-by: NChristian König <christian.koenig@amd.com>
Cc: stable@vger.kernel.org
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

Static checkers complain that probably curly braces were intended here,
but actually it makes more sense to remove the extra tab.
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

Apply the same logic as CI to SI for setting up the
display tiling parameters.  The num banks may vary
per tiling index just like CI.

Bugs:
https://bugs.freedesktop.org/show_bug.cgi?id=71488
https://bugs.freedesktop.org/show_bug.cgi?id=73946
https://bugs.freedesktop.org/show_bug.cgi?id=74927Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

Most laptops seems to have a vblank period of less than
300 and mclk switching works fine.  Drop the quirk and
set the default threshold to 200.

bug:
https://bugzilla.kernel.org/show_bug.cgi?id=70701Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

CIK parts are 128x128, older parts are 64x64.
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

Some hardware may not support standard 64x64 cursors.  Add
a drm cap to query the cursor size from the kernel.  Some examples
include radeon CIK parts (128x128 cursors) and armada (32x64 or 64x32).
This allows things like device specific ddxes to remove asics specific
logic and also allows xf86-video-modesetting to work properly with hw
cursors on this hardware. Default to 64 if the driver doesn't specify
a size.
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>
Reviewed-by: NRob Clark <robdclark@gmail.com>

We were already storing the bpc (bits per color) information
in radeon_crtc, so just use that everywhere rather than
calculating it everywhere we use it.  This also allows us
to change it in one place if we ever want to override it.
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

Merge branch 'drm-nouveau-next' of git://anongit.freedesktop.org/git/nouveau/linux-2.6 into drm-fixes

Nothing too exciting, mostly fixes for ancient boards, but a pretty important fix for DP on some systems.

Thanks,
* 'drm-nouveau-next' of git://anongit.freedesktop.org/git/nouveau/linux-2.6:
  drm/nouveau: fix TTM_PL_TT memtype on pre-nv50
  drm/nv50/disp: use correct register to determine DP display bpp
  drm/nouveau/fb: use correct ram oclass for nv1a hardware
  drm/nv50/gr: add missing nv_error parameter priv
  drm/nouveau: fix ENG_RUNLIST register address
  drm/nv4c/bios: disallow retrieving from prom on nv4x igp's
  drm/nv4c/vga: decode register is in a different place on nv4x igp's
  drm/nv4c/mc: nv4x igp's have a different msi rearm register
  drm/nouveau: set irq_enabled manually

3 fixes plus 1 prep patch, all four cc: stable. Jani will take over from
here and the plan is that he'll do 3.14-fixes for the entire release just
to work things out a bit.

* tag 'drm-intel-fixes-2014-02-14' of ssh://git.freedesktop.org/git/drm-intel:
  drm/i915/dp: add native aux defer retry limit
  drm/i915/dp: increase native aux defer retry timeout
  drm/i915: Prevent MI_DISPLAY_FLIP straddling two cachelines on IVB
  drm/i915: Add intel_ring_cachline_align()

fix for leak in tda998x

* 'tda998x-fixes' of git://ftp.arm.linux.org.uk/~rmk/linux-cubox:
  drm/i2c: tda998x: Fix memory leak in tda998x_encoder_init error path.

Commit a5540906 ("drm/nv50-: map TTM_PL_SYSTEM through a BAR for CPU
access") made it possible to work with tiled memory. However
mem->mm_node is not a nouveau_mem for AGP-using pre-NV50 cards, but a
drm_mm_node, as created by the ttm_bo_manager_func. As such, extend the
untiled check to explicitly include all pre-nv50 cards.
Reported-by: NRonald <ronald645@gmail.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=74613Signed-off-by: NIlia Mirkin <imirkin@alum.mit.edu>
Tested-by: NRonald Uitermark <ronald645@gmail.com>
Acked-by: NMaarten Lankhorst <maarten.lankhorst@canonical.com>
Signed-off-by: NBen Skeggs <bskeggs@redhat.com>

Commit 0a0afd28 ("drm/nv50-/disp: move DP link training to core and
train from supervisor") added code that uses the wrong register for
computing the display bpp, used for bandwidth calculation. Adjust to use
the same register as used by exec_clkcmp and nv50_disp_intr_unk20_2_dp.
Reported-by: NTorsten Wagner <torsten.wagner@gmail.com>
Reported-by: NMichael Gulick <mgulick@mathworks.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=67628
Cc: stable@vger.kernel.org # 3.9+
Signed-off-by: NIlia Mirkin <imirkin@alum.mit.edu>
Signed-off-by: NBen Skeggs <bskeggs@redhat.com>

commit 8613e731
Author: Ben Skeggs <bskeggs@redhat.com>
Date:   Mon Oct 21 08:50:25 2013 +1000

    drm/nouveau/fb: remove ram oclass argument from base fb constructor

Introduced a unfortunate regression by using nv10 ram oclass for nv1a
hardware, causing corruption and eventually system lockup.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=74866Reported-by: NJohn F. Godfrey <jfgodfrey@gmail.com>
Signed-off-by: NEmil Velikov <emil.l.velikov@gmail.com>
Cc: stable@vger.kernel.org # 3.13+
Signed-off-by: NBen Skeggs <bskeggs@redhat.com>

Commit ea7dce90 ("drm/nv50/gr: print mpc trap name when it's not an mp
trap") added an nv_error call that was missing the priv parameter. This
causes GPFs if the error is ever hit.
Signed-off-by: NIlia Mirkin <imirkin@alum.mit.edu>
Signed-off-by: NBen Skeggs <bskeggs@redhat.com>

Address of the ENG_RUNLIST register should be 0x002284 + (engine * 8),
not 0x002284 + (engine * 4).
Signed-off-by: NAlexandre Courbot <acourbot@nvidia.com>
Signed-off-by: NBen Skeggs <bskeggs@redhat.com>

Suggested-by: NMarcin Kościelnicki <koriakin@0x04.net>
Signed-off-by: NIlia Mirkin <imirkin@alum.mit.edu>
Signed-off-by: NBen Skeggs <bskeggs@redhat.com>

Suggested-by: NMarcin Kościelnicki <koriakin@0x04.net>
Signed-off-by: NIlia Mirkin <imirkin@alum.mit.edu>
Signed-off-by: NBen Skeggs <bskeggs@redhat.com>

See https://bugs.freedesktop.org/show_bug.cgi?id=74492Reported-by: NRonald <ronald645@gmail.com>
Suggested-by: NMarcin Kościelnicki <koriakin@0x04.net>
Signed-off-by: NIlia Mirkin <imirkin@alum.mit.edu>
Signed-off-by: NBen Skeggs <bskeggs@redhat.com>

Since commit 0fa9061a ("drm/nouveau/mc: handle irq-related setup
ourselves"), drm_device->irq_enabled remained unset. This is needed in
order to properly wait for a vblank event in the generic drm code.

See https://bugs.freedesktop.org/show_bug.cgi?id=74195Reported-by: NJan Janecek <janjanjanx@gmail.com>
Signed-off-by: NIlia Mirkin <imirkin@alum.mit.edu>
Cc: stable@vger.kernel.org # 3.10+
Signed-off-by: NBen Skeggs <bskeggs@redhat.com>

Pull dma-buf fix from Sumit Semwal:
 "Just some debugfs output updates.

  There's another patch related to dma-buf, but it'll get upstreamed via
  Greg KH's pull request"

* tag 'dma-buf-for-3.14' of git://git.kernel.org/pub/scm/linux/kernel/git/sumits/dma-buf:
  dma-buf: update debugfs output

Pull AVR32 fixes from Hans-Christian Egtvedt.

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/egtvedt/linux-avr32:
  avr32: add generic vga.h to Kbuild
  avr32: add generic ioremap_wc() definition in io.h
  avr32: Makefile: add '-D__linux__' flag for gcc-4.4.7 use
  avr32: fix missing module.h causing build failure in mimc200/fram.c

Pull powerpc fixes from Ben Herrenschmidt:
 "Here are some more powerpc fixes for 3.14

  The main one is a nasty issue with the NUMA balancing support which
  requires a small generic change and the addition of a new accessor to
  set _PAGE_NUMA.  Both have been reviewed and acked by Mel and Rik.

  The changelog should have plenty of details but basically, without
  this fix, we get random user segfaults and/or corruptions due to
  missing TLB/hash flushes.  Aneesh series of 3 patches fixes it.

  We have some vDSO vs.  perf fixes from Anton, some small EEH fixes
  from Gavin, a ppc32 regression vs the stack overflow detector, and a
  fix for the way we handle PCIe host bridge speed settings on pseries
  (which is needed for proper operations of AMD graphics cards on
  Power8)"

* 'merge' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc:
  powerpc/eeh: Disable EEH on reboot
  powerpc/eeh: Cleanup on eeh_subsystem_enabled
  powerpc/powernv: Rework EEH reset
  powerpc: Use unstripped VDSO image for more accurate profiling data
  powerpc: Link VDSOs at 0x0
  mm: Use ptep/pmdp_set_numa() for updating _PAGE_NUMA bit
  mm: Dirty accountable change only apply to non prot numa case
  powerpc/mm: Add new "set" flag argument to pte/pmd update function
  powerpc/pseries: Add Gen3 definitions for PCIE link speed
  powerpc/pseries: Fix regression on PCI link speed
  powerpc: Set the correct ksp_limit on ppc32 when switching to irq stack

This is not a buffer overflow in the traditional sense: we don't
overflow any *kernel* buffers, but we do mis-count the amount of data we
copy back to user space for the SYSLOG_ACTION_READ_ALL case.

In particular, if the user buffer is too small to hold everything, and
*if* there is a continuation line at just the right place, we can end up
giving the user more data than he asked for.

The reason is that we first count up the number of bytes all the log
records contains, then we walk the records again until we've skipped the
records at the beginning that won't fit, and then we walk the rest of
the records and copy them to the user space buffer.

And in between that "skip the initial records that won't fit" and the
"copy the records that *will* fit to user space", we reset the 'prev'
variable that contained the record information for the last record not
copied.  That meant that when we started copying to user space, we now
had a different character count than what we had originally calculated
in the first record walk-through.

The fix is to simply not clear the 'prev' flags value (in both cases
where we had the same logic: syslog_print_all and kmsg_dump_get_buffer:
the latter is used for pstore-like dumping)
Reported-and-tested-by: NDebabrata Banerjee <dbanerje@akamai.com>
Acked-by: NKay Sievers <kay@vrfy.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Need add generic "vga.h", or can not pass building for allmodconfig,
the related error:

    CC [M]  drivers/gpu/drm/drm_irq.o
  In file included from include/linux/vgaarb.h:34,
                   from drivers/gpu/drm/drm_irq.c:42:
  include/video/vga.h:22:21: error: asm/vga.h: No such file or directory
Signed-off-by: NChen Gang <gang.chen.5i5j@gmail.com>
Acked-by: NHans-Christian Egtvedt <hegtvedt@cisco.com>

Need generic ioremap_wc(), or can not pass compiling with allmodconfig,
the related error:

    CC [M]  drivers/gpu/drm/drm_bufs.o
  drivers/gpu/drm/drm_bufs.c: In function 'drm_addmap_core':
  drivers/gpu/drm/drm_bufs.c:217: error: implicit declaration of function 'ioremap_wc'
  drivers/gpu/drm/drm_bufs.c:218: warning: assignment makes pointer from integer without a cast
Signed-off-by: NChen Gang <gang.chen.5i5j@gmail.com>
Acked-by: NHans-Christian Egtvedt <hegtvedt@cisco.com>

For avr32 cross compiler, do not define '__linux__' internally, so it
will cause issue with allmodconfig.

The related error:

    CC [M]  fs/coda/psdev.o
  In file included from include/linux/coda.h:64,
                   from fs/coda/psdev.c:45:
  include/uapi/linux/coda.h:221: error: expected specifier-qualifier-list before 'u_quad_t'

The related toolchain version (which only download, not re-compile):

  [root@gchen linux-next]# /upstream/toolchain/download/avr32-gnu-toolchain-linux_x86/bin/avr32-gcc -v
  Using built-in specs.
  Target: avr32
  Configured with: /data2/home/toolsbuild/jenkins-knuth/workspace/avr32-gnu-toolchain/src/gcc/configure --target=avr32 --host=i686-pc-linux-gnu --build=x86_64-pc-linux-gnu --prefix=/home/toolsbuild/jenkins-knuth/workspace/avr32-gnu-toolchain/avr32-gnu-toolchain-linux_x86 --enable-languages=c,c++ --disable-nls --disable-libssp --disable-libstdcxx-pch --with-dwarf2 --enable-version-specific-runtime-libs --disable-shared --enable-doc --with-mpfr-lib=/home/toolsbuild/jenkins-knuth/workspace/avr32-gnu-toolchain/avr32-gnu-toolchain-linux_x86/lib --with-mpfr-include=/home/toolsbuild/jenkins-knuth/workspace/avr32-gnu-toolchain/avr32-gnu-toolchain-linux_x86/include --with-gmp=/home/toolsbuild/jenkins-knuth/workspace/avr32-gnu-toolchain/avr32-gnu-toolchain-linux_x86 --with-mpc=/home/toolsbuild/jenkins-knuth/workspace/avr32-gnu-toolchain/avr32-gnu-toolchain-linux_x86 --enable-__cxa_atexit --disable-shared --with-newlib --with-pkgversion=AVR_32_bit_GNU_Toolchain_3.4.2_435 --with-bugurl=http://www
.atmel.com/avr
  Thread model: single
  gcc version 4.4.7 (AVR_32_bit_GNU_Toolchain_3.4.2_435)
Signed-off-by: NChen Gang <gang.chen.5i5j@gmail.com>
Acked-by: NHans-Christian Egtvedt <hegtvedt@cisco.com>
Cc: stable@vger.kernel.org

Causing this:

In file included from arch/avr32/boards/mimc200/fram.c:13:
include/linux/miscdevice.h:51: error: field 'list' has incomplete type
include/linux/miscdevice.h:55: error: expected specifier-qualifier-list before 'mode_t'
arch/avr32/boards/mimc200/fram.c:42: error: 'THIS_MODULE' undeclared here (not in a function)
Reported-by: NFengguang Wu <fengguang.wu@intel.com>
Cc: Haavard Skinnemoen <hskinnemoen@gmail.com>
Cc: Hans-Christian Egtvedt <egtvedt@samfundet.no>
Signed-off-by: NPaul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: NSergei Trofimovich <slyfox@gentoo.org>
Acked-by: NHans-Christian Egtvedt <egtvedt@samfundet.no>
Cc: stable@vger.kernel.org

We possiblly detect EEH errors during reboot, particularly in kexec
path, but it's impossible for device drivers and EEH core to handle
or recover them properly.

The patch registers one reboot notifier for EEH and disable EEH
subsystem during reboot. That means the EEH errors is going to be
cleared by hardware reset or second kernel during early stage of
PCI probe.
Signed-off-by: NGavin Shan <shangw@linux.vnet.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

The patch cleans up variable eeh_subsystem_enabled so that we needn't
refer the variable directly from external. Instead, we will use
function eeh_enabled() and eeh_set_enable() to operate the variable.
Signed-off-by: NGavin Shan <shangw@linux.vnet.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

When doing reset in order to recover the affected PE, we issue
hot reset on PE primary bus if it's not root bus. Otherwise, we
issue hot or fundamental reset on root port or PHB accordingly.
For the later case, we didn't cover the situation where PE only
includes root port and it potentially causes kernel crash upon
EEH error to the PE.

The patch reworks the logic of EEH reset to improve the code
readability and also avoid the kernel crash.

Cc: stable@vger.kernel.org
Reported-by: NThadeu Lima de Souza Cascardo <cascardo@linux.vnet.ibm.com>
Signed-off-by: NGavin Shan <shangw@linux.vnet.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

We are seeing a lot of hits in the VDSO that are not resolved by perf.
A while(1) gettimeofday() loop shows the issue:

27.64%  [vdso]  [.] 0x000000000000060c
22.57%  [vdso]  [.] 0x0000000000000628
16.88%  [vdso]  [.] 0x0000000000000610
12.39%  [vdso]  [.] __kernel_gettimeofday
 6.09%  [vdso]  [.] 0x00000000000005f8
 3.58%  test    [.] 00000037.plt_call.gettimeofday@@GLIBC_2.18
 2.94%  [vdso]  [.] __kernel_datapage_offset
 2.90%  test    [.] main

We are using a stripped VDSO image which means only symbols with
relocation info can be resolved. There isn't a lot of point to
stripping the VDSO, the debug info is only about 1kB:

4680 arch/powerpc/kernel/vdso64/vdso64.so
5815 arch/powerpc/kernel/vdso64/vdso64.so.dbg

By using the unstripped image, we can resolve all the symbols in the
VDSO and the perf profile data looks much better:

76.53%  [vdso]  [.] __do_get_tspec
12.20%  [vdso]  [.] __kernel_gettimeofday
 5.05%  [vdso]  [.] __get_datapage
 3.20%  test    [.] main
 2.92%  test    [.] 00000037.plt_call.gettimeofday@@GLIBC_2.18
Signed-off-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

perf is failing to resolve symbols in the VDSO. A while (1)
gettimeofday() loop shows:

93.99%  [vdso]  [.] 0x00000000000005e0
 3.12%  test    [.] 00000037.plt_call.gettimeofday@@GLIBC_2.18
 2.81%  test    [.] main

The reason for this is that we are linking our VDSO shared libraries
at 1MB, which is a little weird. Even though this is uncommon, Alan
points out that it is valid and we should probably fix perf userspace.

Regardless, I can't see a reason why we are doing this. The code
is all position independent and we never rely on the VDSO ending
up at 1M (and we never place it there on 64bit tasks).

Changing our link address to 0x0 fixes perf VDSO symbol resolution:

73.18%  [vdso]  [.] 0x000000000000060c
12.39%  [vdso]  [.] __kernel_gettimeofday
 3.58%  test    [.] 00000037.plt_call.gettimeofday@@GLIBC_2.18
 2.94%  [vdso]  [.] __kernel_datapage_offset
 2.90%  test    [.] main

We still have some local symbol resolution issues that will be
fixed in a subsequent patch.
Signed-off-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Archs like ppc64 doesn't do tlb flush in set_pte/pmd functions when using
a hash table MMU for various reasons (the flush is handled as part of
the PTE modification when necessary).

ppc64 thus doesn't implement flush_tlb_range for hash based MMUs.

Additionally ppc64 require the tlb flushing to be batched within ptl locks.

The reason to do that is to ensure that the hash page table is in sync with
linux page table.

We track the hpte index in linux pte and if we clear them without flushing
hash and drop the ptl lock, we can have another cpu update the pte and can
end up with duplicate entry in the hash table, which is fatal.

We also want to keep set_pte_at simpler by not requiring them to do hash
flush for performance reason. We do that by assuming that set_pte_at() is
never *ever* called on a PTE that is already valid.

This was the case until the NUMA code went in which broke that assumption.

Fix that by introducing a new pair of helpers to set _PAGE_NUMA in a
way similar to ptep/pmdp_set_wrprotect(), with a generic implementation
using set_pte_at() and a powerpc specific one using the appropriate
mechanism needed to keep the hash table in sync.
Acked-by: NMel Gorman <mgorman@suse.de>
Reviewed-by: NRik van Riel <riel@redhat.com>
Signed-off-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

So move it within the if loop
Acked-by: NMel Gorman <mgorman@suse.de>
Reviewed-by: NRik van Riel <riel@redhat.com>
Signed-off-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

pte_update() is a powerpc-ism used to change the bits of a PTE
when the access permission is being restricted (a flush is
potentially needed).

It uses atomic operations on when needed and handles the hash
synchronization on hash based processors.

It is currently only used to clear PTE bits and so the current
implementation doesn't provide a way to also set PTE bits.

The new _PAGE_NUMA bit, when set, is actually restricting access
so it must use that function too, so this change adds the ability
for pte_update() to also set bits.

We will use this later to set the _PAGE_NUMA bit.
Acked-by: NMel Gorman <mgorman@suse.de>
Acked-by: NRik van Riel <riel@redhat.com>
Signed-off-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Rev3 of the PCI Express Base Specification defines a Supported Link
Speeds Vector where the bit definitions within this field are:

Bit 0 - 2.5 GT/s
Bit 1 - 5.0 GT/s
Bit 2 - 8.0 GT/s

This vector definition is used by the platform firmware to export the
maximum and current link speeds of the PCI bus via the
"ibm,pcie-link-speed-stats" device-tree property.

This patch updates pseries_root_bridge_prepare() to detect Gen3
speed buses (defined by 0x04).
Signed-off-by: NKleber Sacilotto de Souza <klebers@linux.vnet.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Commit 5091f0c9 (powerpc/pseries: Fix PCIE link speed endian issue)
introduced a regression on the PCI link speed detection using the
device-tree property. The ibm,pcie-link-speed-stats property is composed
of two 32-bit integers, the first one being the maxinum link speed and
the second the current link speed. The changes introduced by the
aforementioned commit are considering just the first integer.

Fix this issue by changing how the property is accessed, using the
helper functions to properly access the array of values. The explicit
byte swapping is not needed anymore here, since it's done by the helper
functions.
Signed-off-by: NKleber Sacilotto de Souza <klebers@linux.vnet.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Guenter Roeck has got the following call trace on a p2020 board:
  Kernel stack overflow in process eb3e5a00, r1=eb79df90
  CPU: 0 PID: 2838 Comm: ssh Not tainted 3.13.0-rc8-juniper-00146-g19eca00 #4
  task: eb3e5a00 ti: c0616000 task.ti: ef440000
  NIP: c003a420 LR: c003a410 CTR: c0017518
  REGS: eb79dee0 TRAP: 0901   Not tainted (3.13.0-rc8-juniper-00146-g19eca00)
  MSR: 00029000 <CE,EE,ME>  CR: 24008444  XER: 00000000
  GPR00: c003a410 eb79df90 eb3e5a00 00000000 eb05d900 00000001 65d87646 00000000
  GPR08: 00000000 020b8000 00000000 00000000 44008442
  NIP [c003a420] __do_softirq+0x94/0x1ec
  LR [c003a410] __do_softirq+0x84/0x1ec
  Call Trace:
  [eb79df90] [c003a410] __do_softirq+0x84/0x1ec (unreliable)
  [eb79dfe0] [c003a970] irq_exit+0xbc/0xc8
  [eb79dff0] [c000cc1c] call_do_irq+0x24/0x3c
  [ef441f20] [c00046a8] do_IRQ+0x8c/0xf8
  [ef441f40] [c000e7f4] ret_from_except+0x0/0x18
  --- Exception: 501 at 0xfcda524
      LR = 0x10024900
  Instruction dump:
  7c781b78 3b40000a 3a73b040 543c0024 3a800000 3b3913a0 7ef5bb78 48201bf9
  5463103a 7d3b182e 7e89b92e 7c008146 <3ba00000> 7e7e9b78 48000014 57fff87f
  Kernel panic - not syncing: kernel stack overflow
  CPU: 0 PID: 2838 Comm: ssh Not tainted 3.13.0-rc8-juniper-00146-g19eca00 #4
  Call Trace:

The reason is that we have used the wrong register to calculate the
ksp_limit in commit cbc9565e (powerpc: Remove ksp_limit on ppc64).
Just fix it.

As suggested by Benjamin Herrenschmidt, also add the C prototype of the
function in the comment in order to avoid such kind of errors in the
future.

Cc: stable@vger.kernel.org # 3.12
Reported-by: NGuenter Roeck <linux@roeck-us.net>
Tested-by: NGuenter Roeck <linux@roeck-us.net>
Signed-off-by: NKevin Hao <haokexin@gmail.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>