The 47x core's MCSR varies from 44x, so it needs it's own machine check
handler.
Signed-off-by: NDave Kleikamp <shaggy@linux.vnet.ibm.com>
Signed-off-by: NJosh Boyer <jwboyer@linux.vnet.ibm.com>

include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h

percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files.  percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.

percpu.h -> slab.h dependency is about to be removed.  Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability.  As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.

  http://userweb.kernel.org/~tj/misc/slabh-sweep.py

The script does the followings.

* Scan files for gfp and slab usages and update includes such that
  only the necessary includes are there.  ie. if only gfp is used,
  gfp.h, if slab is used, slab.h.

* When the script inserts a new include, it looks at the include
  blocks and try to put the new include such that its order conforms
  to its surrounding.  It's put in the include block which contains
  core kernel includes, in the same order that the rest are ordered -
  alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
  doesn't seem to be any matching order.

* If the script can't find a place to put a new include (mostly
  because the file doesn't have fitting include block), it prints out
  an error message indicating which .h file needs to be added to the
  file.

The conversion was done in the following steps.

1. The initial automatic conversion of all .c files updated slightly
   over 4000 files, deleting around 700 includes and adding ~480 gfp.h
   and ~3000 slab.h inclusions.  The script emitted errors for ~400
   files.

2. Each error was manually checked.  Some didn't need the inclusion,
   some needed manual addition while adding it to implementation .h or
   embedding .c file was more appropriate for others.  This step added
   inclusions to around 150 files.

3. The script was run again and the output was compared to the edits
   from #2 to make sure no file was left behind.

4. Several build tests were done and a couple of problems were fixed.
   e.g. lib/decompress_*.c used malloc/free() wrappers around slab
   APIs requiring slab.h to be added manually.

5. The script was run on all .h files but without automatically
   editing them as sprinkling gfp.h and slab.h inclusions around .h
   files could easily lead to inclusion dependency hell.  Most gfp.h
   inclusion directives were ignored as stuff from gfp.h was usually
   wildly available and often used in preprocessor macros.  Each
   slab.h inclusion directive was examined and added manually as
   necessary.

6. percpu.h was updated not to include slab.h.

7. Build test were done on the following configurations and failures
   were fixed.  CONFIG_GCOV_KERNEL was turned off for all tests (as my
   distributed build env didn't work with gcov compiles) and a few
   more options had to be turned off depending on archs to make things
   build (like ipr on powerpc/64 which failed due to missing writeq).

   * x86 and x86_64 UP and SMP allmodconfig and a custom test config.
   * powerpc and powerpc64 SMP allmodconfig
   * sparc and sparc64 SMP allmodconfig
   * ia64 SMP allmodconfig
   * s390 SMP allmodconfig
   * alpha SMP allmodconfig
   * um on x86_64 SMP allmodconfig

8. percpu.h modifications were reverted so that it could be applied as
   a separate patch and serve as bisection point.

Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.
Signed-off-by: NTejun Heo <tj@kernel.org>
Guess-its-ok-by: NChristoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>

die.lock needs to be a real spinlock in RT. Convert it to
raw_spinlock.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

powerpc/booke: Add support for advanced debug registers

From: Dave Kleikamp <shaggy@linux.vnet.ibm.com>

Based on patches originally written by Torez Smith.

This patch defines context switch and trap related functionality
for BookE specific Debug Registers. It adds support to ptrace()
for setting and getting BookE related Debug Registers
Signed-off-by: NDave Kleikamp <shaggy@linux.vnet.ibm.com>
Cc: Torez Smith  <lnxtorez@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Gibson <dwg@au1.ibm.com>
Cc: Josh Boyer <jwboyer@linux.vnet.ibm.com>
Cc: Kumar Gala <galak@kernel.crashing.org>
Cc: Sergio Durigan Junior <sergiodj@br.ibm.com>
Cc: Thiago Jung Bauermann <bauerman@br.ibm.com>
Cc: linuxppc-dev list <Linuxppc-dev@ozlabs.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

powerpc/booke: Introduce new CONFIG options for advanced debug registers

From: Dave Kleikamp <shaggy@linux.vnet.ibm.com>

Introduce new config options to simplify the ifdefs pertaining to the
advanced debug registers for booke and 40x processors:

CONFIG_PPC_ADV_DEBUG_REGS - boolean: true for dac-based processors
CONFIG_PPC_ADV_DEBUG_IACS - number of IAC registers
CONFIG_PPC_ADV_DEBUG_DACS - number of DAC registers
CONFIG_PPC_ADV_DEBUG_DVCS - number of DVC registers
CONFIG_PPC_ADV_DEBUG_DAC_RANGE - DAC ranges supported

Beginning conservatively, since I only have the facilities to test 440
hardware.  I believe all 40x and booke platforms support at least 2 IAC
and 2 DAC registers.  For 440, 4 IAC and 2 DVC registers are enabled, as
well as the DAC ranges.
Signed-off-by: NDave Kleikamp <shaggy@linux.vnet.ibm.com>
Acked-by: NDavid Gibson <dwg@au1.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

With NO_HZ it is useful to know how often the decrementer is going off. The
patch below adds an entry for it and also adds it into the /proc/stat
summaries.

While here, I added performance monitoring and machine check exceptions.
I found it useful to keep an eye on the PMU exception rate
when using the perf tool. Since it's possible to take a completely
handled machine check on a System p box it also sounds like a good idea to
keep a machine check summary.

The event naming matches x86 to keep gratuitous differences to a minimum.
Signed-off-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Add printout of last accessed sysfs file, added to x86 in
ae87221d (sysfs: crash debugging)

Also add the notify_die hook that allows us to print out the ftrace
buffer on oops. This is useful in conjunction with ftrace function_graph:

Oops: Kernel access of bad area, sig: 11 [#1]
SMP NR_CPUS=128 NUMA pSeries
last sysfs file: /sys/class/net/tunl0/type
Dumping ftrace buffer:

...

  0)               |                .sysrq_handle_crash() {
  0)   0.476 us    |                  .hash_page();
  0)   0.488 us    |                  .xmon_fault_handler();
  0)               |                  .bad_page_fault() {
  0)               |                    .search_exception_tables() {
  0)   0.590 us    |                      .search_module_extables();
  0)   2.546 us    |                    }
  0)               |                    .printk() {
  0)               |                      .vprintk() {
  0)   0.488 us    |                        ._raw_spin_lock();
  0)   0.572 us    |                        .emit_log_char();

Showing the function graph of a sysrq-c crash.
Signed-off-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Using perf to trace L1 dcache misses and dumping data addresses I found a few
variables taking a lot of misses. Since they are almost never written, they
should go into the __read_mostly section.
Signed-off-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Suggested by Roland.

Implement user_single_step_siginfo() for powerpc.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Acked-by: NRoland McGrath <roland@redhat.com>
Cc: <linux-arch@vger.kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The code under "if (is_global_init())" is bogus, and is_global_init()
itself is not right in mt case.

Contrary to what the comment says, nowadays force_sig_info() does kill
init even if the handler is SIG_DFL. Note that force_sig_info() clears
SIGNAL_UNKILLABLE exactly for this case.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

perf_event wants a separate event for alignment and emulation faults,
so create another emulation event.  This will make it easy to hook in
perf_event at one spot.

We pass in regs which will be required for these events.
Signed-off-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

Reworked by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

This adds block-step support on powerpc, including a PTRACE_SINGLEBLOCK
request for ptrace.

The BookE implementation is tweaked to fire a single step after a
block step in order to mimmic the server behaviour.
Signed-off-by: NRoland McGrath <roland@redhat.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

If CONFIG_PPC_EMULATED_STATS is enabled, make available counters for the
various classes of emulated instructions under
/sys/kernel/debug/powerpc/emulated_instructions/ (assumed debugfs is mounted on
/sys/kernel/debug).  Optionally (controlled by
/sys/kernel/debug/powerpc/emulated_instructions/do_warn), rate-limited warnings
can be printed to the console when instructions are emulated.
Signed-off-by: NGeert Uytterhoeven <Geert.Uytterhoeven@sonycom.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

The e500mc supports the new msgsnd/doorbell mechanisms that were added in
the Power ISA 2.05 architecture.  We use the normal level doorbell for
doing SMP IPIs at this point.
Signed-off-by: NKumar Gala <galak@kernel.crashing.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Create a new header that becomes a single location for defining PowerPC
opcodes used by code that is either generationg instructions
at runtime (fixups, debug, etc.), emulating instructions, or just
compiling instructions old assemblers don't know about.

We currently don't handle the floating point emulation or alignment decode
as both are better handled by the specific decode support they already
have.

Added support for the new dcbzl, dcbal, msgsnd, tlbilx, & wait instructions
since older assemblers don't know about them.
Signed-off-by: NKumar Gala <galak@kernel.crashing.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

This patch add the handlers of SPE/EFP exceptions.
The code is used to emulate float point arithmetic,
when MSR(SPE) is enabled and receive EFP data interrupt or EFP round interrupt.

This patch has no conflict with or dependence on FP math-emu.

The code has been tested by TestFloat.

Now the code doesn't support SPE/EFP instructions emulation
(it won't be called when receive program interrupt),
but it could be easily added.
Signed-off-by: NLiu Yu <yu.liu@freescale.com>
Signed-off-by: NKumar Gala <galak@kernel.crashing.org>

This patch also includes the required removal of (unused) inclusion of
<asm/a.out.h> <linux/a.out.h>'s in the arch/ code for these
architectures.

[dwmw2: updated for 2.6.27-rc]
Signed-off-by: NAdrian Bunk <bunk@kernel.org>
Signed-off-by: NDavid Woodhouse <David.Woodhouse@intel.com>

This patch implements support for HW based watchpoint via the
DBSR_DAC (Data Address Compare) facility of the BookE processors.

It does so by interfacing with the existing DABR breakpoint code
and adding the necessary bits and pieces for the new bits to
be properly set or cleared
Signed-off-by: NLuis Machado <luisgpm@br.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

This patch extends the floating point save and restore code to use the
VSX load/stores when VSX is available.  This will make FP context
save/restore marginally slower on FP only code, when VSX is available,
as it has to load/store 128bits rather than just 64bits.

Mixing FP, VMX and VSX code will get constant architected state.

The signals interface is extended to enable access to VSR 0-31
doubleword 1 after discussions with tool chain maintainers.  Backward
compatibility is maintained.

The ptrace interface is also extended to allow access to VSR 0-31 full
registers.
Signed-off-by: NMichael Neuling <mikey@neuling.org>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

This patch is based on work done by Madhvesh. R. Sulibhavi back in
March 2007.

We refactor some of the single step handling since it differs between
"classic" and "booke" powerpc cores.
Signed-off-by: NKumar Gala <galak@kernel.crashing.org>

Looks like "[POWERPC] kdump shutdown hook support" broke builds when
CONFIG_DEBUGGER=n and CONFIG_KEXEC=y, such as in g5_defconfig:

arch/powerpc/kernel/crash.c: In function 'default_machine_crash_shutdown':
arch/powerpc/kernel/crash.c:388: error: '__debugger_fault_handler' undeclared (first use in this function)
arch/powerpc/kernel/crash.c:388: error: (Each undeclared identifier is reported only once
arch/powerpc/kernel/crash.c:388: error: for each function it appears in.)

Move the debugger hooks to under CONFIG_DEBUGGER || CONFIG_KEXEC, since
that's when the crash code is enabled.

(I should have caught this with my build-script pre-merge, my bad. :( )
Signed-off-by: NOlof Johansson <olof@lixom.net>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

This adds a cputable function pointer for the CPU-side machine
check handling. The semantic is still the same as the old one,
the one in ppc_md. overrides the one in cputable, though
ultimately we'll want to change that so the CPU gets first.

This removes CONFIG_440A which was a problem for multiplatform
kernels and instead fixes up the IVOR at runtime from a setup_cpu
function. The "A" version of the machine check also tweaks the
regs->trap value to differenciate the 2 versions at the C level.
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: NJosh Boyer <jwboyer@linux.vnet.ibm.com>

isel (Integer Select) is a new user space instruction in the
PowerISA 2.04 spec.  Not all processors implement it so lets emulate
to ensure code built with isel will run everywhere.
Signed-off-by: NKumar Gala <galak@kernel.crashing.org>

One of the easiest things to isolate is the pid printed in kernel log.
There was a patch, that made this for arch-independent code, this one makes
so for arch/xxx files.

It took some time to cross-compile it, but hopefully these are all the
printks in arch code.
Signed-off-by: NAlexey Dobriyan <adobriyan@openvz.org>
Signed-off-by: NPavel Emelyanov <xemul@openvz.org>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

is_init() is an ambiguous name for the pid==1 check.  Split it into
is_global_init() and is_container_init().

A cgroup init has it's tsk->pid == 1.

A global init also has it's tsk->pid == 1 and it's active pid namespace
is the init_pid_ns.  But rather than check the active pid namespace,
compare the task structure with 'init_pid_ns.child_reaper', which is
initialized during boot to the /sbin/init process and never changes.

Changelog:

	2.6.22-rc4-mm2-pidns1:
	- Use 'init_pid_ns.child_reaper' to determine if a given task is the
	  global init (/sbin/init) process. This would improve performance
	  and remove dependence on the task_pid().

	2.6.21-mm2-pidns2:

	- [Sukadev Bhattiprolu] Changed is_container_init() calls in {powerpc,
	  ppc,avr32}/traps.c for the _exception() call to is_global_init().
	  This way, we kill only the cgroup if the cgroup's init has a
	  bug rather than force a kernel panic.

[akpm@linux-foundation.org: fix comment]
[sukadev@us.ibm.com: Use is_global_init() in arch/m32r/mm/fault.c]
[bunk@stusta.de: kernel/pid.c: remove unused exports]
[sukadev@us.ibm.com: Fix capability.c to work with threaded init]
Signed-off-by: NSerge E. Hallyn <serue@us.ibm.com>
Signed-off-by: NSukadev Bhattiprolu <sukadev@us.ibm.com>
Acked-by: NPavel Emelianov <xemul@openvz.org>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Cedric Le Goater <clg@fr.ibm.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Cc: Herbert Poetzel <herbert@13thfloor.at>
Cc: Kirill Korotaev <dev@sw.ru>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Implement show_unhandled_signals sysctl + support to print when a process
is killed due to unhandled signals just as i386 and x86_64 does.

Default to having it off, unlike x86 that defaults on.
Signed-off-by: NOlof Johansson <olof@lixom.net>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

Previously, Soft_emulate_8xx was called with no implementation, resulting in
build failures whenever building 8xx without math emulation.  The
implementation is copied from arch/ppc to resolve this issue.

However, this sort of minimal emulation is not a very good idea other than
for compatibility with existing userspaces, as it's less efficient than
soft-float and can mislead users into believing they have soft-float.  Thus,
it is made a configurable option, off by default.
Signed-off-by: NScott Wood <scottwood@freescale.com>
Signed-off-by: NKumar Gala <galak@kernel.crashing.org>

Move out the old-style exception parsers to a separate function, and
don't call it on platforms that have a platform-specific handler.

It would make sense to move out the generic versions into their platforms
instead, but that can be done gradually down the road.
Signed-off-by: NOlof Johansson <olof@lixom.net>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

Remove leftover cruft from ARCH=ppc.

There are no users of platform_machine_check() in ARCH=powerpc, and none
should be added (they should use ppc_md.machine_check_handler instead).
Signed-off-by: NOlof Johansson <olof@lixom.net>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

Reserved MCSR bits on FSL BookE parts may have spurious values
when mcheck occurs.  Mask these off when printing the MCSR to
avoid confusion.  Also, get rid of the MCSR_GL_CI bit defined
for e500 - this bit doesn't actually have any meaning.
Signed-off-by: NBecky Bruce <becky.bruce@freescale.com>
Signed-off-by: NKumar Gala <galak@kernel.crashing.org>

If the kernel OOPSed or BUGed then it probably should be considered as
tainted.  Thus, all subsequent OOPSes and SysRq dumps will report the
tainted kernel.  This saves a lot of time explaining oddities in the
calltraces.
Signed-off-by: NPavel Emelianov <xemul@openvz.org>
Acked-by: NRandy Dunlap <randy.dunlap@oracle.com>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
[ Added parisc patch from Matthew Wilson  -Linus ]
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The current generic bug implementation has a call to dump_stack() in case a
WARN_ON(whatever) gets hit.  Since report_bug(), which calls dump_stack(),
gets called from an exception handler we can do better: just pass the
pt_regs structure to report_bug() and pass it to show_regs() in case of a
warning.  This will give more debug informations like register contents,
etc...  In addition this avoids some pointless lines that dump_stack()
emits, since it includes a stack backtrace of the exception handler which
is of no interest in case of a warning.  E.g.  on s390 the following lines
are currently always present in a stack backtrace if dump_stack() gets
called from report_bug():

 [<000000000001517a>] show_trace+0x92/0xe8)
 [<0000000000015270>] show_stack+0xa0/0xd0
 [<00000000000152ce>] dump_stack+0x2e/0x3c
 [<0000000000195450>] report_bug+0x98/0xf8
 [<0000000000016cc8>] illegal_op+0x1fc/0x21c
 [<00000000000227d6>] sysc_return+0x0/0x10
Acked-by: NJeremy Fitzhardinge <jeremy@goop.org>
Acked-by: NHaavard Skinnemoen <hskinnemoen@atmel.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Kyle McMartin <kyle@parisc-linux.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This patch moves the die notifier handling to common code.  Previous
various architectures had exactly the same code for it.  Note that the new
code is compiled unconditionally, this should be understood as an appel to
the other architecture maintainer to implement support for it aswell (aka
sprinkling a notify_die or two in the proper place)

arm had a notifiy_die that did something totally different, I renamed it to
arm_notify_die as part of the patch and made it static to the file it's
declared and used at.  avr32 used to pass slightly less information through
this interface and I brought it into line with the other architectures.

[akpm@linux-foundation.org: build fix]
[akpm@linux-foundation.org: fix vmalloc_sync_all bustage]
[bryan.wu@analog.com: fix vmalloc_sync_all in nommu]
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Cc: <linux-arch@vger.kernel.org>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: NBryan Wu <bryan.wu@analog.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Looks like someone got this backwards, highlighting the perils of the
? : !!! :)
Signed-off-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

Handle recursive oopses, like on x86. We had a few cases recently where
we locked up in oops printing and didnt make it into crashdump.
Signed-off-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

Move pmac_backlight_unblank into its own function and only take the
pmac_backlight_mutex when we are on a pmac for that added bit of
paranoia.
Signed-off-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

Add missing oops_enter/oops_exit, makes pause_on_oops boot parameter work.
Signed-off-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

Per device data such as brightness belongs to the indivdual device
and should therefore be separate from the the backlight operation
function pointers. This patch splits the two types of data and
allows simplifcation of some code.
Signed-off-by: NRichard Purdie <rpurdie@rpsys.net>

backlight_device->sem has a very specific use as documented in the
header file. The external users of this are using it for a different
reason, to serialise access to the update_status() method.

backlight users were supposed to implement their own internal
serialisation of update_status() if needed but everyone is doing
things differently and incorrectly. Therefore add a global mutex to
take care of serialisation for everyone, once and for all.

Locking for get_brightness remains optional since most users don't
need it.

Also update the lcd class in a similar way.
Signed-off-by: NRichard Purdie <rpurdie@rpsys.net>

When we do full FP emulation its possible that we need to post a SIGFPE based
on the results of the emulation.  The previous code ignored this case completely.

Additionally, the Soft_emulate_8xx case had two issues.  One, we should never
generate a SIGFPE since the code only does data movement.  Second, we were
interpreting the return codes incorrectly, it returns 0 on success, 1 on
illop and -EFAULT on a data access error.
Signed-off-by: NKumar Gala <galak@kernel.crashing.org>