<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux.git/arch/arm/kernel/process.c, branch v3.17</title>
<subtitle>Linux kernel source tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/'/>
<entry>
<title>ARM: 8148/1: flush TLS and thumbee register state during exec</title>
<updated>2014-09-16T15:09:32+00:00</updated>
<author>
<name>Nathan Lynch</name>
<email>nathan_lynch@mentor.com</email>
</author>
<published>2014-09-11T01:49:08+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=fbfb872f5f417cea48760c535e0ff027c88b507a'/>
<id>fbfb872f5f417cea48760c535e0ff027c88b507a</id>
<content type='text'>
The TPIDRURO and TPIDRURW registers need to be flushed during exec;
otherwise TLS information is potentially leaked.  TPIDRURO in
particular needs careful treatment.  Since flush_thread basically
needs the same code used to set the TLS in arm_syscall, pull that into
a common set_tls helper in tls.h and use it in both places.

Similarly, TEEHBR needs to be cleared during exec as well.  Clearing
its save slot in thread_info isn't right as there is no guarantee
that a thread switch will occur before the new program runs.  Just
setting the register directly is sufficient.

Signed-off-by: Nathan Lynch &lt;nathan_lynch@mentor.com&gt;
Acked-by: Will Deacon &lt;will.deacon@arm.com&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Russell King &lt;rmk+kernel@arm.linux.org.uk&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The TPIDRURO and TPIDRURW registers need to be flushed during exec;
otherwise TLS information is potentially leaked.  TPIDRURO in
particular needs careful treatment.  Since flush_thread basically
needs the same code used to set the TLS in arm_syscall, pull that into
a common set_tls helper in tls.h and use it in both places.

Similarly, TEEHBR needs to be cleared during exec as well.  Clearing
its save slot in thread_info isn't right as there is no guarantee
that a thread switch will occur before the new program runs.  Just
setting the register directly is sufficient.

Signed-off-by: Nathan Lynch &lt;nathan_lynch@mentor.com&gt;
Acked-by: Will Deacon &lt;will.deacon@arm.com&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Russell King &lt;rmk+kernel@arm.linux.org.uk&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge branch 'for-linus' of git://ftp.arm.linux.org.uk/~rmk/linux-arm</title>
<updated>2014-04-11T18:56:40+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2014-04-11T18:56:40+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=ede1d63fccb7a397832ddbdee5951ec65194d93e'/>
<id>ede1d63fccb7a397832ddbdee5951ec65194d93e</id>
<content type='text'>
Pull second set of ARM changes from Russell King:
 "This is the remainder of the ARM changes for this merge window.
  Included in this request are:

   - fixes for kprobes for big-endian support
   - fix tracing in soft_restart
   - avoid phys address overflow in kdump code
   - fix reporting of read-only pmd bits in kernel page table dump
   - remove unnecessary (and possibly buggy) call to outer_flush_all()
   - fix a three sparse warnings (missing header file for function
     prototypes)
   - fix pj4 crashing single zImage (thanks to arm-soc merging changes
     which enables this with knowledge that the corresponding fix had
     not even been submitted for my tree before the merge window opened)
   - vfp macro cleanups
   - dump register state on undefined instruction userspace faults when
     debugging"

* 'for-linus' of git://ftp.arm.linux.org.uk/~rmk/linux-arm:
  Dump the registers on undefined instruction userspace faults
  ARM: 8018/1: Add {inc,dec}_preempt_count asm macros
  ARM: 8017/1: Move asm macro get_thread_info to asm/assembler.h
  ARM: 8016/1: Check cpu id in pj4_cp0_init.
  ARM: 8015/1: Add cpu_is_pj4 to distinguish PJ4 because it has some differences with V7
  ARM: add missing system_misc.h include to process.c
  ARM: 8009/1: dcscb.c: remove call to outer_flush_all()
  ARM: 8014/1: mm: fix reporting of read-only PMD bits
  ARM: 8012/1: kdump: Avoid overflow when converting pfn to physaddr
  ARM: 8010/1: avoid tracers in soft_restart
  ARM: kprobes-test: Workaround GAS .align bug
  ARM: kprobes-test: use &lt;asm/opcodes.h&gt; for Thumb instruction building
  ARM: kprobes-test: use &lt;asm/opcodes.h&gt; for ARM instruction building
  ARM: kprobes-test: use &lt;asm/opcodes.h&gt; for instruction accesses
  ARM: probes: fix instruction fetch order with &lt;asm/opcodes.h&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull second set of ARM changes from Russell King:
 "This is the remainder of the ARM changes for this merge window.
  Included in this request are:

   - fixes for kprobes for big-endian support
   - fix tracing in soft_restart
   - avoid phys address overflow in kdump code
   - fix reporting of read-only pmd bits in kernel page table dump
   - remove unnecessary (and possibly buggy) call to outer_flush_all()
   - fix a three sparse warnings (missing header file for function
     prototypes)
   - fix pj4 crashing single zImage (thanks to arm-soc merging changes
     which enables this with knowledge that the corresponding fix had
     not even been submitted for my tree before the merge window opened)
   - vfp macro cleanups
   - dump register state on undefined instruction userspace faults when
     debugging"

* 'for-linus' of git://ftp.arm.linux.org.uk/~rmk/linux-arm:
  Dump the registers on undefined instruction userspace faults
  ARM: 8018/1: Add {inc,dec}_preempt_count asm macros
  ARM: 8017/1: Move asm macro get_thread_info to asm/assembler.h
  ARM: 8016/1: Check cpu id in pj4_cp0_init.
  ARM: 8015/1: Add cpu_is_pj4 to distinguish PJ4 because it has some differences with V7
  ARM: add missing system_misc.h include to process.c
  ARM: 8009/1: dcscb.c: remove call to outer_flush_all()
  ARM: 8014/1: mm: fix reporting of read-only PMD bits
  ARM: 8012/1: kdump: Avoid overflow when converting pfn to physaddr
  ARM: 8010/1: avoid tracers in soft_restart
  ARM: kprobes-test: Workaround GAS .align bug
  ARM: kprobes-test: use &lt;asm/opcodes.h&gt; for Thumb instruction building
  ARM: kprobes-test: use &lt;asm/opcodes.h&gt; for ARM instruction building
  ARM: kprobes-test: use &lt;asm/opcodes.h&gt; for instruction accesses
  ARM: probes: fix instruction fetch order with &lt;asm/opcodes.h&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge branches 'fixes' and 'misc' into for-next</title>
<updated>2014-04-11T13:50:05+00:00</updated>
<author>
<name>Russell King</name>
<email>rmk+kernel@arm.linux.org.uk</email>
</author>
<published>2014-04-11T13:50:05+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=53f1d9afb4c85c4d6a107420188d84ddf76ebbc0'/>
<id>53f1d9afb4c85c4d6a107420188d84ddf76ebbc0</id>
<content type='text'>
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
</pre>
</div>
</content>
</entry>
<entry>
<title>ARM: add missing system_misc.h include to process.c</title>
<updated>2014-04-08T14:29:37+00:00</updated>
<author>
<name>Russell King</name>
<email>rmk+kernel@arm.linux.org.uk</email>
</author>
<published>2014-04-06T15:17:39+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=779dd9590b00bd91b7811c24f0df34a9d91bfa0f'/>
<id>779dd9590b00bd91b7811c24f0df34a9d91bfa0f</id>
<content type='text'>
arm_pm_restart(), arm_pm_idle() and soft_restart() are all declared in
system_misc.h, but this file is not included in process.c.  Add this
missing include.  Found via sparse:

arch/arm/kernel/process.c:98:6: warning: symbol 'soft_restart' was not declared. Should it be static?
arch/arm/kernel/process.c:127:6: warning: symbol 'arm_pm_restart' was not declared. Should it be static?
arch/arm/kernel/process.c:134:6: warning: symbol 'arm_pm_idle' was not declared. Should it be static?

Signed-off-by: Russell King &lt;rmk+kernel@arm.linux.org.uk&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
arm_pm_restart(), arm_pm_idle() and soft_restart() are all declared in
system_misc.h, but this file is not included in process.c.  Add this
missing include.  Found via sparse:

arch/arm/kernel/process.c:98:6: warning: symbol 'soft_restart' was not declared. Should it be static?
arch/arm/kernel/process.c:127:6: warning: symbol 'arm_pm_restart' was not declared. Should it be static?
arch/arm/kernel/process.c:134:6: warning: symbol 'arm_pm_idle' was not declared. Should it be static?

Signed-off-by: Russell King &lt;rmk+kernel@arm.linux.org.uk&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ARM: 8010/1: avoid tracers in soft_restart</title>
<updated>2014-04-07T11:10:00+00:00</updated>
<author>
<name>Sebastian Capella</name>
<email>sebastian.capella@linaro.org</email>
</author>
<published>2014-03-25T00:18:35+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=c7d442f46c1bb18e48204f41c3d838c475eb5130'/>
<id>c7d442f46c1bb18e48204f41c3d838c475eb5130</id>
<content type='text'>
Use of tracers in local_irq_disable is causes abort loops when called
with irqs disabled using a temporary stack.  Replace local_irq_disable
with raw_local_irq_disable instead to avoid tracers.

Signed-off-by: Sebastian Capella &lt;sebastian.capella@linaro.org&gt;
Signed-off-by: Russell King &lt;rmk+kernel@arm.linux.org.uk&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Use of tracers in local_irq_disable is causes abort loops when called
with irqs disabled using a temporary stack.  Replace local_irq_disable
with raw_local_irq_disable instead to avoid tracers.

Signed-off-by: Sebastian Capella &lt;sebastian.capella@linaro.org&gt;
Signed-off-by: Russell King &lt;rmk+kernel@arm.linux.org.uk&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge branch 'for-linus' of git://ftp.arm.linux.org.uk/~rmk/linux-arm</title>
<updated>2014-04-05T20:20:43+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2014-04-05T20:20:43+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=2d1eb87ae1e6f3999e77989fd2f831b134270787'/>
<id>2d1eb87ae1e6f3999e77989fd2f831b134270787</id>
<content type='text'>
Pull ARM changes from Russell King:

 - Perf updates from Will Deacon:
   - Support for Qualcomm Krait processors (run perf on your phone!)
   - Support for Cortex-A12 (run perf stat on your FPGA!)
   - Support for perf_sample_event_took, allowing us to automatically decrease
     the sample rate if we can't handle the PMU interrupts quickly enough
     (run perf record on your FPGA!).

 - Basic uprobes support from David Long:
     This patch series adds basic uprobes support to ARM. It is based on
     patches developed earlier by Rabin Vincent. That approach of adding
     hooks into the kprobes instruction parsing code was not well received.
     This approach separates the ARM instruction parsing code in kprobes out
     into a separate set of functions which can be used by both kprobes and
     uprobes. Both kprobes and uprobes then provide their own semantic action
     tables to process the results of the parsing.

 - ARMv7M (microcontroller) updates from Uwe Kleine-König

 - OMAP DMA updates (recently added Vinod's Ack even though they've been
   sitting in linux-next for a few months) to reduce the reliance of
   omap-dma on the code in arch/arm.

 - SA11x0 changes from Dmitry Eremin-Solenikov and Alexander Shiyan

 - Support for Cortex-A12 CPU

 - Align support for ARMv6 with ARMv7 so they can cooperate better in a
   single zImage.

 - Addition of first AT_HWCAP2 feature bits for ARMv8 crypto support.

 - Removal of IRQ_DISABLED from various ARM files

 - Improved efficiency of virt_to_page() for single zImage

 - Patch from Ulf Hansson to permit runtime PM callbacks to be available for
   AMBA devices for suspend/resume as well.

 - Finally kill asm/system.h on ARM.

* 'for-linus' of git://ftp.arm.linux.org.uk/~rmk/linux-arm: (89 commits)
  dmaengine: omap-dma: more consolidation of CCR register setup
  dmaengine: omap-dma: move IRQ handling to omap-dma
  dmaengine: omap-dma: move register read/writes into omap-dma.c
  ARM: omap: dma: get rid of 'p' allocation and clean up
  ARM: omap: move dma channel allocation into plat-omap code
  ARM: omap: dma: get rid of errata global
  ARM: omap: clean up DMA register accesses
  ARM: omap: remove almost-const variables
  ARM: omap: remove references to disable_irq_lch
  dmaengine: omap-dma: cleanup errata 3.3 handling
  dmaengine: omap-dma: provide register read/write functions
  dmaengine: omap-dma: use cached CCR value when enabling DMA
  dmaengine: omap-dma: move barrier to omap_dma_start_desc()
  dmaengine: omap-dma: move clnk_ctrl setting to preparation functions
  dmaengine: omap-dma: improve efficiency loading C.SA/C.EI/C.FI registers
  dmaengine: omap-dma: consolidate clearing channel status register
  dmaengine: omap-dma: move CCR buffering disable errata out of the fast path
  dmaengine: omap-dma: provide register definitions
  dmaengine: omap-dma: consolidate setup of CCR
  dmaengine: omap-dma: consolidate setup of CSDP
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull ARM changes from Russell King:

 - Perf updates from Will Deacon:
   - Support for Qualcomm Krait processors (run perf on your phone!)
   - Support for Cortex-A12 (run perf stat on your FPGA!)
   - Support for perf_sample_event_took, allowing us to automatically decrease
     the sample rate if we can't handle the PMU interrupts quickly enough
     (run perf record on your FPGA!).

 - Basic uprobes support from David Long:
     This patch series adds basic uprobes support to ARM. It is based on
     patches developed earlier by Rabin Vincent. That approach of adding
     hooks into the kprobes instruction parsing code was not well received.
     This approach separates the ARM instruction parsing code in kprobes out
     into a separate set of functions which can be used by both kprobes and
     uprobes. Both kprobes and uprobes then provide their own semantic action
     tables to process the results of the parsing.

 - ARMv7M (microcontroller) updates from Uwe Kleine-König

 - OMAP DMA updates (recently added Vinod's Ack even though they've been
   sitting in linux-next for a few months) to reduce the reliance of
   omap-dma on the code in arch/arm.

 - SA11x0 changes from Dmitry Eremin-Solenikov and Alexander Shiyan

 - Support for Cortex-A12 CPU

 - Align support for ARMv6 with ARMv7 so they can cooperate better in a
   single zImage.

 - Addition of first AT_HWCAP2 feature bits for ARMv8 crypto support.

 - Removal of IRQ_DISABLED from various ARM files

 - Improved efficiency of virt_to_page() for single zImage

 - Patch from Ulf Hansson to permit runtime PM callbacks to be available for
   AMBA devices for suspend/resume as well.

 - Finally kill asm/system.h on ARM.

* 'for-linus' of git://ftp.arm.linux.org.uk/~rmk/linux-arm: (89 commits)
  dmaengine: omap-dma: more consolidation of CCR register setup
  dmaengine: omap-dma: move IRQ handling to omap-dma
  dmaengine: omap-dma: move register read/writes into omap-dma.c
  ARM: omap: dma: get rid of 'p' allocation and clean up
  ARM: omap: move dma channel allocation into plat-omap code
  ARM: omap: dma: get rid of errata global
  ARM: omap: clean up DMA register accesses
  ARM: omap: remove almost-const variables
  ARM: omap: remove references to disable_irq_lch
  dmaengine: omap-dma: cleanup errata 3.3 handling
  dmaengine: omap-dma: provide register read/write functions
  dmaengine: omap-dma: use cached CCR value when enabling DMA
  dmaengine: omap-dma: move barrier to omap_dma_start_desc()
  dmaengine: omap-dma: move clnk_ctrl setting to preparation functions
  dmaengine: omap-dma: improve efficiency loading C.SA/C.EI/C.FI registers
  dmaengine: omap-dma: consolidate clearing channel status register
  dmaengine: omap-dma: move CCR buffering disable errata out of the fast path
  dmaengine: omap-dma: provide register definitions
  dmaengine: omap-dma: consolidate setup of CCR
  dmaengine: omap-dma: consolidate setup of CSDP
  ...
</pre>
</div>
</content>
</entry>
<entry>
<title>sched/idle, ARM: Remove redundant cpuidle_idle_call()</title>
<updated>2014-02-11T08:58:22+00:00</updated>
<author>
<name>Nicolas Pitre</name>
<email>nicolas.pitre@linaro.org</email>
</author>
<published>2014-01-29T17:45:09+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=ad68cc7a777948b77f15a3dc3510918ff87ed0c0'/>
<id>ad68cc7a777948b77f15a3dc3510918ff87ed0c0</id>
<content type='text'>
The core idle loop now takes care of it.

Signed-off-by: Nicolas Pitre &lt;nico@linaro.org&gt;
Acked-by: Daniel Lezcano &lt;daniel.lezcano@linaro.org&gt;
Cc: Preeti U Murthy &lt;preeti@linux.vnet.ibm.com&gt;
Cc: Paul Mundt &lt;lethal@linux-sh.org&gt;
Cc: "Rafael J. Wysocki" &lt;rjw@rjwysocki.net&gt;
Cc: linux-arm-kernel@lists.infradead.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-sh@vger.kernel.org
Cc: linux-pm@vger.kernel.org
Cc: Russell King &lt;linux@arm.linux.org.uk&gt;
Cc: linaro-kernel@lists.linaro.org
Cc: Benjamin Herrenschmidt &lt;benh@kernel.crashing.org&gt;
Signed-off-by: Peter Zijlstra &lt;peterz@infradead.org&gt;
Link: http://lkml.kernel.org/n/tip-y2nbw5j3ma5siy5584919z5i@git.kernel.org
Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The core idle loop now takes care of it.

Signed-off-by: Nicolas Pitre &lt;nico@linaro.org&gt;
Acked-by: Daniel Lezcano &lt;daniel.lezcano@linaro.org&gt;
Cc: Preeti U Murthy &lt;preeti@linux.vnet.ibm.com&gt;
Cc: Paul Mundt &lt;lethal@linux-sh.org&gt;
Cc: "Rafael J. Wysocki" &lt;rjw@rjwysocki.net&gt;
Cc: linux-arm-kernel@lists.infradead.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-sh@vger.kernel.org
Cc: linux-pm@vger.kernel.org
Cc: Russell King &lt;linux@arm.linux.org.uk&gt;
Cc: linaro-kernel@lists.linaro.org
Cc: Benjamin Herrenschmidt &lt;benh@kernel.crashing.org&gt;
Signed-off-by: Peter Zijlstra &lt;peterz@infradead.org&gt;
Link: http://lkml.kernel.org/n/tip-y2nbw5j3ma5siy5584919z5i@git.kernel.org
Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ARM: show_regs: on v7-M there are no FIQs, different processor modes, ...</title>
<updated>2014-02-03T16:30:21+00:00</updated>
<author>
<name>Uwe Kleine-König</name>
<email>u.kleine-koenig@pengutronix.de</email>
</author>
<published>2013-12-16T09:38:57+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=e2e55fde3f2eaeb1d341508108a51a61dd0fb470'/>
<id>e2e55fde3f2eaeb1d341508108a51a61dd0fb470</id>
<content type='text'>
no indication about irqs in PSR and only a single ISA. So skip the whole
decoding and just print the xPSR on v7-M.

Also mark two static variables as __maybe_unused to prevent the compiler
from emitting:

	arch/arm/kernel/process.c:51:20: warning: 'processor_modes' defined but not used [-Wunused-variable]
	arch/arm/kernel/process.c:58:20: warning: 'isa_modes' defined but not used [-Wunused-variable]

Signed-off-by: Uwe Kleine-König &lt;u.kleine-koenig@pengutronix.de&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
no indication about irqs in PSR and only a single ISA. So skip the whole
decoding and just print the xPSR on v7-M.

Also mark two static variables as __maybe_unused to prevent the compiler
from emitting:

	arch/arm/kernel/process.c:51:20: warning: 'processor_modes' defined but not used [-Wunused-variable]
	arch/arm/kernel/process.c:58:20: warning: 'isa_modes' defined but not used [-Wunused-variable]

Signed-off-by: Uwe Kleine-König &lt;u.kleine-koenig@pengutronix.de&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ARM: 7912/1: check stack pointer in get_wchan</title>
<updated>2013-12-09T23:24:31+00:00</updated>
<author>
<name>Konstantin Khlebnikov</name>
<email>k.khlebnikov@samsung.com</email>
</author>
<published>2013-12-05T13:21:36+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=1b15ec7a7427d4188ba91b9bbac696250a059d22'/>
<id>1b15ec7a7427d4188ba91b9bbac696250a059d22</id>
<content type='text'>
get_wchan() is lockless. Task may wakeup at any time and change its own stack,
thus each next stack frame may be overwritten and filled with random stuff.

/proc/$pid/stack interface had been disabled for non-current tasks, see [1]
But 'wchan' still allows to trigger stack frame unwinding on volatile stack.

This patch fixes oops in unwind_frame() by adding stack pointer validation on
each step (as x86 code do), unwind_frame() already checks frame pointer.

Also I've found another report of this oops on stackoverflow (irony).

Link: http://www.spinics.net/lists/arm-kernel/msg110589.html [1]
Link: http://stackoverflow.com/questions/18479894/unwind-frame-cause-a-kernel-paging-error

Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Konstantin Khlebnikov &lt;k.khlebnikov@samsung.com&gt;
Acked-by: Will Deacon &lt;will.deacon@arm.com&gt;
Signed-off-by: Russell King &lt;rmk+kernel@arm.linux.org.uk&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
get_wchan() is lockless. Task may wakeup at any time and change its own stack,
thus each next stack frame may be overwritten and filled with random stuff.

/proc/$pid/stack interface had been disabled for non-current tasks, see [1]
But 'wchan' still allows to trigger stack frame unwinding on volatile stack.

This patch fixes oops in unwind_frame() by adding stack pointer validation on
each step (as x86 code do), unwind_frame() already checks frame pointer.

Also I've found another report of this oops on stackoverflow (irony).

Link: http://www.spinics.net/lists/arm-kernel/msg110589.html [1]
Link: http://stackoverflow.com/questions/18479894/unwind-frame-cause-a-kernel-paging-error

Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Konstantin Khlebnikov &lt;k.khlebnikov@samsung.com&gt;
Acked-by: Will Deacon &lt;will.deacon@arm.com&gt;
Signed-off-by: Russell King &lt;rmk+kernel@arm.linux.org.uk&gt;
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<entry>
<title>Merge branch 'security-fixes' into fixes</title>
<updated>2013-08-13T19:23:28+00:00</updated>
<author>
<name>Russell King</name>
<email>rmk+kernel@arm.linux.org.uk</email>
</author>
<published>2013-08-13T19:23:28+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=2a2822475d0e734adffab72644329d9c042ce2e1'/>
<id>2a2822475d0e734adffab72644329d9c042ce2e1</id>
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</content>
<content type='xhtml'>
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<pre>
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