When the driver is unloading, the nvme transport could be in the process
of submitting new requests, will send abort requests to terminate
associations, or may make LS-related requests.  The driver's abort and
request entry points currently is ignorant of the unloading state and is
starting the requests even though the infrastructure to complete them
continues to teardown.

Change the entry points for new requests to check whether unloading and
if so, reject the requests. Abort routines check unloading, and if so,
noop the request. An abort is noop'd as the teardown paths are already
aborting/terminating the io outstanding at the time the teardown
initiated.
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <james.smart@broadcom.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

The driver's interaction with the host nvme transport has been incorrect
for a while. The driver did not wait for the unregister callbacks
(waited only 5 jiffies). Thus the driver may remove objects that may be
referenced by subsequent abort commands from the transport, and the
actual unregister callback was effectively a noop. This was especially
problematic if the driver was unloaded.

The driver now waits for the unregister callbacks, as it should, before
continuing with teardown.
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <james.smart@broadcom.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

The driver currently registers any remote port that has NVME support.
It should only be registering target ports.

Register only target ports.
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <james.smart@broadcom.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

During RSCN storms, the driver does not rediscover some targets.  The
driver marks some RSCN as to be handled after the ones it's working
on. The driver missed processing some deferred RSCN.

Move where the driver checks for deferred RSCNs and initiate deferred
RSCN handling if the flag was set. Also revise nport state within the
RSCN confirm routine. Add some state data to a possible debug print to
aid future debugging.
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <james.smart@broadcom.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

pt2pt ndlp ref count prematurely goes to 0. There was reference removed
that should only be removed if connected to a switch, not if in
point-to-point mode.

Add a mode check before the reference remove.
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <james.smart@broadcom.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

The current default for async hw receive queues is 1, which presents
issues under heavy load as number of queues influence the available
async receive buffer limits.

Raise the default to the either the current hw limit (16) or the number
of hw qs configured (io channel value).

Revise the attribute definition for mrq to better reflect what we do for
hw queues. E.g. 0 means default to optimal (# of cpus), non-zero
specifies a specific limit. Before this change, mrq=0 meant target mode
was disabled. As 0 now has a different meaning, rework the if tests to
use the better nvmet_support check.
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <james.smart@broadcom.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Display for lpfc/fnX/iDiag/queInfo isn't formatted perfectly.  Corrected
the format strings for the queue info debug messages.
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <james.smart@broadcom.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

The driver does not respond to PLOGI from the direct attach target.  The
driver uses incorrect S_ID in CONFIG_LINK, after FLOGI completion

Correct by issuing CONFIG_LINK with the correct S_ID after receiving the
PLOGI from the target
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <james.smart@broadcom.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Raise the maximum NVME sg list size allowed to 256 elements.
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <james.smart@broadcom.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Performing an LS abort results in the following message being seen:
  0603 Invalid CQ subtype 6: 00000300 22000002 ffff0016 d0050000
and the associated exchange is not properly freed.

The code did not recognize the exchange type that was aborted, thus it
was not properly handled.

Correct by adding the NVME LS ELS type to the exchange types that are
recognized.
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <james.smart@broadcom.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

In test cases where an instance of the driver is detached and
reattached, the driver will crash on reattachment. There is a compound
if statement that will skip over the bar setup if the pci_resource_start
call is not successful. The driver erroneously returns success to its
bar setup in this scenario even though the bars aren't properly
configured.

Rework the offending code segment for proper initialization steps.  If
the pci_resource_start call fails, -ENOMEM is now returned.

Sample stack:

rport-5:0-10: blocked FC remote port time out: removing rport
BUG: unable to handle kernel NULL pointer dereference at           (null)
... lpfc_sli4_wait_bmbx_ready+0x32/0x70 [lpfc]
...
...  RIP: 0010:...  ... lpfc_sli4_wait_bmbx_ready+0x32/0x70 [lpfc]
 Call Trace:
  ... lpfc_sli4_post_sync_mbox+0x106/0x4d0 [lpfc]
  ... ? __alloc_pages_nodemask+0x176/0x420
  ... ? __kmalloc+0x2e/0x230
  ... lpfc_sli_issue_mbox_s4+0x533/0x720 [lpfc]
  ... ? mempool_alloc+0x69/0x170
  ... ? dma_generic_alloc_coherent+0x8f/0x140
  ... lpfc_sli_issue_mbox+0xf/0x20 [lpfc]
  ... lpfc_sli4_driver_resource_setup+0xa6f/0x1130 [lpfc]
  ... ? lpfc_pci_probe_one+0x23e/0x16f0 [lpfc]
  ... lpfc_pci_probe_one+0x445/0x16f0 [lpfc]
  ... local_pci_probe+0x45/0xa0
  ... work_for_cpu_fn+0x14/0x20
  ... process_one_work+0x17a/0x440

Cc: <stable@vger.kernel.org> # 4.12+
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <james.smart@broadcom.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

XRI_ABORTED_CQE completions were not being handled in the fast path.
They were being queued and deferred to the lpfc worker thread for
processing. This is an artifact of the driver design prior to moving
queue processing out of the isr and into a workq element. Now that queue
processing is already in a deferred context, remove this artifact and
process them directly.
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <james.smart@broadcom.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Hardware queues are a fast staging area to push commands into the
adapter.  The adapter should drain them extremely quickly. However,
under heavy io load, the host cpu is pushing commands faster than the
drain rate of the adapter causing the driver to resource busy commands.

Enlarge the hardware queue (wq & cq) to support a larger number of queue
entries (4x the prior size) before backpressure. Enlarging the queue
requires larger contiguous buffers (16k) per logical page for the
hardware. This changed calling sequences that were expecting 4K page
sizes that now must pass a parameter with the page sizes. It also
required use of a new version of an adapter command that can vary the
page size values.
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <james.smart@broadcom.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

When the HBA is connected to a private loop, the driver reports FLOGI
loop-open failure as functional error. This is an expected condition.

Mark loop-open failure as a warning instead of error.
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <james.smart@broadcom.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

The pointer 'port' is being assigned but it is never read, hence it is
redundant and can be removed. Cleans up clang warning:

drivers/scsi/bfa/bfad_attr.c:505:2: warning: Value stored to 'port' is
never read.
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Variable managed_request_id is being assigned but it is never read,
hence it is redundant and can be removed. Cleans up clang warning:

drivers/scsi/aacraid/linit.c:706:5: warning: Value stored to
'managed_request_id' is never read
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Fix kernel-doc function name and comments in st.c::read_ns_show():
change us to ns to match the function name.
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Correct another typo I20 to I2O.
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

There is no need to #define the license of the driver, just put it in
the MODULE_LICENSE() line directly as a text string.

This allows tools that check that the module license matches the source
code license to work properly, as there is no need to unwind the
unneeded dereference, especially when the string is defined in a .h file
far away from the .c file it is used in.

Cc: "James E.J. Bottomley" <jejb@linux.vnet.ibm.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Varun Prakash <varun@chelsio.com>
Reported-by: Philippe Ombredanne <pombredanne@nexb.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

The TW_IOCTL_GET_LOCK ioctl uses do_gettimeofday() to check whether a
lock has expired. This can misbehave due to a concurrent settimeofday()
call, as it is based on 'real' time, and it will overflow in y2038 on
32-bit architectures, producing unexpected results when used across the
overflow time.

This changes it to using monotonic time, using ktime_get() to simplify
the code.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Adam Radford <aradford@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

The calculation of the number of seconds since Sunday 00:00:00 overflows
in 2106, meaning that we instead will return the seconds since Wednesday
06:28:16 afterwards.

Using 64-bit time stamps avoids this slight inconsistency, and the
deprecated do_gettimeofday(), replacing it with the simpler
ktime_get_real_seconds().
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Adam Radford <aradford@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

twl_aen_queue_event/twa_aen_queue_event, we use do_gettimeofday() to
read the lower 32 bits of the current time in seconds, to pass them to
the TW_IOCTL_GET_NEXT_EVENT ioctl or the 3ware_aen_read sysfs file.

This will overflow on all architectures in year 2106, there is not much
we can do about that without breaking the ABI. User space has 90 years
to learn to deal with it, so it's probably ok.

I'm changing it to use ktime_get_real_seconds() with a comment to
document what happens when.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Adam Radford <aradford@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

bfa_aen_entry_s is passed through a netlink socket that can be read by
either 32-bit or 64-bit processes, but the data format is different
between the two on current implementations.

Originally, this was using a 'struct timeval', which also suffers from
getting redefined with a new libc implementation.

With this patch, the layout gets fixed to having two 64-bit members for
the time, making it the same on 32-bit kernels and 64-bit kernels
running either compat or native user space including x32.

Provided that the new header file gets used to recompile any 32-bit
application binaries, this will fix running those on a 64-bit kernel
(with or without this patch) e.g. in a container environment, and it
will make binaries work that will be built against a future 32-bit glibc
that uses a 64-bit time_t, and avoid the y2038 overflow there.

However, this also breaks compatibility with any existing 32-bit binary
running on a native 32-bit kernel, those must be recompiled against the
new header, which in turn makes them incompatible with older kernels
unless the same change gets applied there.

Obviously this patch should only be applied when the benefits outweigh
the possible breakage. I'm posting it under the assumption that there
are no open-source tools using the netlink interface, and that users of
the binaries provided by qlogic for SLES10/11 and RHEL5/6 are not
actually being used on new future systems with 32-bit x86 kernels.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Anil Gurumurthy <Anil.Gurumurthy@cavium.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

bfa_aen_entry_s is passed to user space in a netlink message, but is
defined using a 'struct timeval' and an 'enum' that are not only
different between architectures, but also between 32-bit user space and
64-bit kernels they may run on, as well as depending on the particular C
library that defines timeval.

This changes the in-kernel definition to no longer use the timeval type
directly but instead use two open-coded 'unsigned long' members.  This
keeps the existing ABI, but making the variable unsigned also helps make
it work after y2038, until it overflows in 2106.

Since the macro becomes overly complex at this point, I'm changing it to
an inline function for readability.

I'm not changing the 32-bit user-space ABI at this point, to keep the
changes separate, I deally this would be defined using the same binary
layout for all architectures.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Anil Gurumurthy <Anil.Gurumurthy@cavium.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

The bfa_get_log_time() returns a 64-bit timestamp that does not suffer
from the y2038 overflow on 64-bit systems. However, on 32-bit
architectures the timestamp will jump from 0x000000007fffffff to
0xffffffff80000000 in y2038 and produce wrong results.

The ktime_get_real_seconds() function does the same thing as
bfa_get_log_time() without that problem, so we can simply remove the
former use ktime_get_real_seconds() instead.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Anil Gurumurthy <Anil.Gurumurthy@cavium.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

io_profile_start_time() gets read using do_gettimeofday() and passed
down as a 32-bit value through multiple functions. This will overflow in
y2038 or y2106, depending on whether it gets interpreted as unsigned in
the end.

This changes do_gettimeofday() to ktime_get_real_seconds() and pushes
the point at which it overflows to where we actually assign it to the
bfa_fcpim_del_itn_stats_s structure, with an appropriate comment.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Anil Gurumurthy <Anil.Gurumurthy@cavium.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

In bfa_ioc_send_enable, we use the deprecated do_gettimeofday() function
to read the current time. This is not a problem, since the firmware
interface is already limited to 32-bit timestamps, but it's better to
use ktime_get_seconds() and document what the limitation is.

I noticed that I did the same change in commit a5af8392 ("bna: avoid
writing uninitialized data into hw registers") for the ethernet
driver. That commit also changed the "disable" funtion to initialize the
data we pass to the firmware properly, so I'm doing the same thing here.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Anil Gurumurthy <Anil.Gurumurthy@cavium.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

We use the deprecated do_gettimeofday() function to read the current
time when resetting the statistics in both bfa_port and bfa_svc. This
works fine because overflow is handled correctly, but we want to get rid
of do_gettimeofday() and using a non-monotonic time suffers from
concurrent settimeofday calls and other problems.

This uses the ktime_get_seconds() function instead, which does what we
need here.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Anil Gurumurthy <Anil.Gurumurthy@cavium.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

BFA_TRC_TS() calculates a 32-bit microsecond timestamp using the
deprecated do_gettimeofday() function. This overflows roughly every 71
minutes, so it's obviously not used as an absolute time stamp, but it
seems wrong to use a time base for it that will jump during
settimeofday() calls, leap seconds, or the y2038 overflow.

This converts it to ktime_get_ts64(), which has none of those problems
but is not synchronized to wall-clock time.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Anil Gurumurthy <Anil.Gurumurthy@cavium.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

In preparation to enabling -Wimplicit-fallthrough, mark switch cases
where we are expecting to fall through.

Addresses-Coverity-ID: 114988
Addresses-Coverity-ID: 114989
Addresses-Coverity-ID: 114990
Addresses-Coverity-ID: 114991
Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Make use of the swap macro and remove unnecessary variable tmp.  This
makes the code easier to read and maintain.

This code was detected with the help of Coccinelle.
Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
Acked-by: Manish Rangankar <Manish.Rangankar@cavium.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Pull ARM fixes from Russell King:

 - LPAE fixes for kernel-readonly regions

 - Fix for get_user_pages_fast on LPAE systems

 - avoid tying decompressor to a particular platform if DEBUG_LL is
   enabled

 - BUG if we attempt to return to userspace but the to-be-restored PSR
   value keeps us in privileged mode (defeating an issue that ftracetest
   found)

* 'fixes' of git://git.armlinux.org.uk/~rmk/linux-arm:
  ARM: BUG if jumping to usermode address in kernel mode
  ARM: 8722/1: mm: make STRICT_KERNEL_RWX effective for LPAE
  ARM: 8721/1: mm: dump: check hardware RO bit for LPAE
  ARM: make decompressor debug output user selectable
  ARM: fix get_user_pages_fast

Pull irq fixes from Thomas Glexiner:

 - unbreak the irq trigger type check for legacy platforms

 - a handful fixes for ARM GIC v3/4 interrupt controllers

 - a few trivial fixes all over the place

* 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  genirq/matrix: Make - vs ?: Precedence explicit
  irqchip/imgpdc: Use resource_size function on resource object
  irqchip/qcom: Fix u32 comparison with value less than zero
  irqchip/exiu: Fix return value check in exiu_init()
  irqchip/gic-v3-its: Remove artificial dependency on PCI
  irqchip/gic-v4: Add forward definition of struct irq_domain_ops
  irqchip/gic-v3: pr_err() strings should end with newlines
  irqchip/s3c24xx: pr_err() strings should end with newlines
  irqchip/gic-v3: Fix ppi-partitions lookup
  irqchip/gic-v4: Clear IRQ_DISABLE_UNLAZY again if mapping fails
  genirq: Track whether the trigger type has been set

Pull misc x86 fixes from Ingo Molnar:
 - topology enumeration fixes
 - KASAN fix
 - two entry fixes (not yet the big series related to KASLR)
 - remove obsolete code
 - instruction decoder fix
 - better /dev/mem sanity checks, hopefully working better this time
 - pkeys fixes
 - two ACPI fixes
 - 5-level paging related fixes
 - UMIP fixes that should make application visible faults more debuggable
 - boot fix for weird virtualization environment

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits)
  x86/decoder: Add new TEST instruction pattern
  x86/PCI: Remove unused HyperTransport interrupt support
  x86/umip: Fix insn_get_code_seg_params()'s return value
  x86/boot/KASLR: Remove unused variable
  x86/entry/64: Add missing irqflags tracing to native_load_gs_index()
  x86/mm/kasan: Don't use vmemmap_populate() to initialize shadow
  x86/entry/64: Fix entry_SYSCALL_64_after_hwframe() IRQ tracing
  x86/pkeys/selftests: Fix protection keys write() warning
  x86/pkeys/selftests: Rename 'si_pkey' to 'siginfo_pkey'
  x86/mpx/selftests: Fix up weird arrays
  x86/pkeys: Update documentation about availability
  x86/umip: Print a warning into the syslog if UMIP-protected instructions are used
  x86/smpboot: Fix __max_logical_packages estimate
  x86/topology: Avoid wasting 128k for package id array
  perf/x86/intel/uncore: Cache logical pkg id in uncore driver
  x86/acpi: Reduce code duplication in mp_override_legacy_irq()
  x86/acpi: Handle SCI interrupts above legacy space gracefully
  x86/boot: Fix boot failure when SMP MP-table is based at 0
  x86/mm: Limit mmap() of /dev/mem to valid physical addresses
  x86/selftests: Add test for mapping placement for 5-level paging
  ...

Pull scheduler fixes from Ingo Molnar:
 "Misc fixes: a documentation fix, a Sparse warning fix and a debugging
  fix"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/debug: Fix task state recording/printout
  sched/deadline: Don't use dubious signed bitfields
  sched/deadline: Fix the description of runtime accounting in the documentation

Pull perf fixes from Ingo Molnar:
 "Misc fixes: two PMU driver fixes and a memory leak fix"

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf/core: Fix memory leak triggered by perf --namespace
  perf/x86/intel/uncore: Add event constraint for BDX PCU
  perf/x86/intel: Hide TSX events when RTM is not supported

Pull static key fix from Ingo Molnar:
 "Fix a boot warning related to bad init ordering of the static keys
  self-test"

* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  jump_label: Invoke jump_label_test() via early_initcall()

Pull objtool fixes from Ingo Molnar:
 "A handful of objtool fixes, most of them related to making the UAPI
  header-syncing warnings easier to read and easier to act upon"

* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  tools/headers: Sync objtool UAPI header
  objtool: Fix cross-build
  objtool: Move kernel headers/code sync check to a script
  objtool: Move synced files to their original relative locations
  objtool: Make unreachable annotation inline asms explicitly volatile
  objtool: Add a comment for the unreachable annotation macros

Detect if we are returning to usermode via the normal kernel exit paths
but the saved PSR value indicates that we are in kernel mode.  This
could occur due to corrupted stack state, which has been observed with
"ftracetest".

This ensures that we catch the problem case before we get to user code.
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>