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This removes an OProfile dependency on the spufs module. This
dependency was causing a problem for multiplatform systems that are
built with support for Oprofile on Cell but try to load the oprofile
module on a non-Cell system.
Signed-off-by: Bob Nelson <rrnelson@us.ibm.com>
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Acked-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
This changes the spu context switch code to not write to reserved bits
of spu interrupt status register.
The architecture book says the reserved fields should be set to zero.
Signed-off-by: Masato Noguchi <Masato.Noguchi@jp.sony.com>
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Based on original patches from
Arnd Bergmann <arnd.bergman@de.ibm.com>; and
Luke Browning <lukebr@linux.vnet.ibm.com>
Currently, spu contexts need to be loaded to the SPU in order to take
class 0 and class 1 exceptions.
This change makes the actual interrupt-handlers much simpler (ie,
set the exception information in the context save area), and defers the
handling code to the spufs_handle_class[01] functions, called from
spufs_run_spu.
This should improve the concurrency of the spu scheduling leading to
greater SPU utilization when SPUs are overcommited.
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Add a few #defines for the class 0, 1 and 2 interrupt status bits, and
use them instead of magic numbers when we're setting or checking for
these interrupts.
Also, add a #define for the class 2 mailbox threshold interrupt mask.
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Currently, part of the spufs code (switch.o, lscsa_alloc.o and fault.o)
is compiled directly into the kernel.
This change moves these components of spufs into the kernel.
The lscsa and switch objects are fairly straightforward to move in.
For the fault.o module, we split the fault-handling code into two
parts: a/p/p/c/spu_fault.c and a/p/p/c/spufs/fault.c. The former is for
the in-kernel spu_handle_mm_fault function, and we move the rest of the
fault-handling code into spufs.
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Currently, we have a possibilty that the SLBs setup during context
switch don't cover the entirety of the necessary lscsa and code
regions, if these regions cross a segment boundary.
This change checks the start and end of each region, and inserts a SLB
entry for each, if unique. We also remove the assumption that the
spu_save_code and spu_restore_code reside in the same segment, by using
the specific code array for save and restore.
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Add a function spu_64k_pages_available(), so that we can abstract the
explicity use of mmu_psize_defs() in lssca_alloc.c
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Currently, the SPU context switch code (spufs/switch.c) sets up the
SPU's SLBs directly, which requires some low-level mm stuff.
This change moves the kernel SLB setup to spu_base.c, by exposing
a function spu_setup_kernel_slbs() to do this setup. This allows us
to remove the low-level mm code from switch.c, making it possible
to later move switch.c to the spufs module.
Also, add a struct spu_slb for the cases where we need to deal with
SLB entries.
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Rework spufs_coredump_extra_notes_write() to check for and return errors.
If we're coredumping to a pipe we can't trust file->f_pos, we need to
maintain the foffset value passed to us. The cleanest way to do this is
to have the low level write routine increment foffset when we've
successfully written.
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Because spufs might be built as a module, we can't have other parts of the
kernel calling directly into it, we need stub routines that check first if the
module is loaded.
Currently we have two structures which hold callbacks for these stubs, the
syscalls are in spufs_calls and the coredump calls are in spufs_coredump_calls.
In both cases the logic for registering/unregistering is essentially the same,
so we can simplify things by combining the two.
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Acked-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
spu_create and spu_run are wrapped by the cell syscall layer, so
we don't need the asmlinkage.
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
At present, a built-in spufs will not use the spufs_calls callbacks, but
directly call sys_spu_create. This saves us an indirect branch, but
means we have duplicated functions - one for CONFIG_SPU_FS=y and one for
=m.
This change unifies the spufs syscall path, and provides access to the
spufs_calls structure through a get/put pair. At present, the only user
of the spufs_calls structure is spu_syscalls.c, but this will facilitate
adding the coredump calls later.
Everyone likes numbers, right? Here's a before/after comparison with
CONFIG_SPU_FS=y, doing spu_create(); close(); 64k times.
Before:
[jk@cell ~]$ time ./spu_create
performing 65536 spu_create calls
real 0m24.075s
user 0m0.146s
sys 0m23.925s
After:
[jk@cell ~]$ time ./spu_create
performing 65536 spu_create calls
real 0m24.777s
user 0m0.141s
sys 0m24.631s
So, we're adding around 11us per syscall, at the benefit of having
only one syscall path.
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
The Cell BE Architecture spec states that the SPU MFC Class 0 interrupt
is edge-triggered. The current spu interrupt handler assumes this
behavior and does not clear the interrupt status.
The PS3 hypervisor visualizes all SPU interrupts as level, and on return
from the interrupt handler the hypervisor will deliver a new virtual
interrupt for any unmasked interrupts which for which the status has not
been cleared. This fix clears the interrupt status in the interrupt
handler.
Signed-off-by: Masato Noguchi <Masato.Noguchi@jp.sony.com>
Signed-off-by: Geoff Levand <geoffrey.levand@am.sony.com>
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Acked-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
This sorts out the various lists and related locks in the spu code.
In detail:
- the per-node free_spus and active_list are gone. Instead struct spu
gained an alloc_state member telling whether the spu is free or not
- the per-node spus array is now locked by a per-node mutex, which
takes over from the global spu_lock and the per-node active_mutex
- the spu_alloc* and spu_free function are gone as the state change is
now done inline in the spufs code. This allows some more sharing of
code for the affinity vs normal case and more efficient locking
- some little refactoring in the affinity code for this locking scheme
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
From: Maynard Johnson <mpjohn@us.ibm.com>
This patch updates the existing arch/powerpc/oprofile/op_model_cell.c
to add in the SPU profiling capabilities. In addition, a 'cell' subdirectory
was added to arch/powerpc/oprofile to hold Cell-specific SPU profiling code.
Exports spu_set_profile_private_kref and spu_get_profile_private_kref which
are used by OProfile to store private profile information in spufs data
structures.
Also incorporated several fixes from other patches (rrn). Check pointer
returned from kzalloc. Eliminated unnecessary cast. Better error
handling and cleanup in the related area. 64-bit unsigned long parameter
was being demoted to 32-bit unsigned int and eventually promoted back to
unsigned long.
Signed-off-by: Carl Love <carll@us.ibm.com>
Signed-off-by: Maynard Johnson <mpjohn@us.ibm.com>
Signed-off-by: Bob Nelson <rrnelson@us.ibm.com>
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Acked-by: Paul Mackerras <paulus@samba.org>
This patch adds support for additional flags at spu_create, which relate
to the establishment of affinity between contexts and contexts to memory.
A fourth, optional, parameter is supported. This parameter represent
a affinity neighbor of the context being created, and is used when defining
SPU-SPU affinity.
Affinity is represented as a doubly linked list of spu_contexts.
Signed-off-by: Andre Detsch <adetsch@br.ibm.com>
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
This patch adds affinity data to each spu instance.
A doubly linked list is created, meant to connect the spus
in the physical order they are placed in the BE. SPUs
near to memory should be marked as having memory affinity.
Adjustments of the fields acording to FW properties is done
in separate patches, one for CPBW, one for Malta (patch for
Malta under testing).
Signed-off-by: Andre Detsch <adetsch@br.ibm.com>
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Addition of a spufs-global "cbe_info" array. Each entry contains information
about one Cell/B.E. node, namelly:
* list of spus (both free and busy spus are in this list);
* list of free spus (replacing the static spu_list from spu_base.c)
* number of spus;
* number of reserved (non scheduleable) spus.
SPE affinity implementation actually requires only access to one spu per
BE node (since it implements its own pointer to walk through the other spus
of the ring) and the number of scheduleable spus (n_spus - non_sched_spus)
However having this more general structure can be useful for other
functionalities, concentrating per-cbe statistics / data.
Signed-off-by: Andre Detsch <adetsch@br.ibm.com>
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
This patch exports per-context statistics in spufs as long as spu
statistics in sysfs.
It was formed by merging:
"spufs: add spu stats in sysfs" From: Christoph Hellwig
"spufs: add stat file to spufs" From: Christoph Hellwig
"spufs: fix libassist accounting" From: Jeremy Kerr
"spusched: fix spu utilization statistics" From: Luke Browning
And some adjustments by myself, after suggestions on cbe-oss-dev.
Having separate patches was making the review process harder
than it should, as we end up integrating spus and ctx statistics
accounting much more than it was on the first implementation.
Signed-off-by: Andre Detsch <adetsch@br.ibm.com>
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
The current SPU context saving procedure in SPUFS unexpectedly
restarts MFC when halting decrementer, because MFC_CNTL[Dh] is set
without MFC_CNTL[Sm]. This bug causes, for example, saving broken DMA
queues. Here is a patch to fix the problem.
Signed-off-by: Kazunori Asayama <asayama@sm.sony.co.jp>
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
This patch adds support for investigating spus information after a
kernel crash event, through kdump vmcore file.
Implementation is based on xmon code, but the new functionality was
kept independent from xmon.
Signed-off-by: Lucio Jose Herculano Correia <luciojhc@br.ibm.com>
Signed-off-by: Andre Detsch <adetsch@br.ibm.com>
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Add a bit define from book, and replace one hex number with a
symbol, for clarity.
Signed-off-by: Sebastian Siewior <bigeasy@linux.vnet.ibm.com>
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
The SPU code doesn't properly invalidate SPUs SLBs when necessary,
for example when changing a segment size from the hugetlbfs code. In
addition, it saves and restores the SLB content on context switches
which makes it harder to properly handle those invalidations.
This patch removes the saving & restoring for now, something more
efficient might be found later on. It also adds a spu_flush_all_slbs(mm)
that can be used by the core mm code to flush the SLBs of all SPEs that
are running a given mm at the time of the flush.
In order to do that, it adds a spinlock to the list of all SPEs and move
some bits & pieces from spufs to spu_base.c
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
It doesn't make any sense to have a priority field in the physical spu
structure. Move it into the spu context instead.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Spu management ops in arch/platforms/cell/spu_priv1_mmio.h can be used
commonly in of based platform. This patch separates spu management ops
from native cell code and uses on celleb platform.
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Signed-off-by: Kou Ishizaki <kou.ishizaki@toshiba.co.jp>
Signed-off-by: Paul Mackerras <paulus@samba.org>
This adds a platform specific spu management abstraction and the coresponding
routines to support the IBM Cell Blade. It also removes the hypervisor only
resources that were included in struct spu.
Three new platform specific routines are introduced, spu_enumerate_spus(),
spu_create_spu() and spu_destroy_spu(). The underlying design uses a new
type, struct spu_management_ops, to hold function pointers that the platform
setup code is expected to initialize to instances appropriate to that platform.
For the IBM Cell Blade support, I put the hypervisor only resources that were
in struct spu into a platform specific data structure struct spu_pdata.
Signed-off-by: Geoff Levand <geoffrey.levand@am.sony.com>
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
This patch adds SPU elf notes to the coredump. It creates a separate note
for each of /regs, /fpcr, /lslr, /decr, /decr_status, /mem, /signal1,
/signal1_type, /signal2, /signal2_type, /event_mask, /event_status,
/mbox_info, /ibox_info, /wbox_info, /dma_info, /proxydma_info, /object-id.
A new macro, ARCH_HAVE_EXTRA_NOTES, was created for architectures to
specify they have extra elf core notes.
A new macro, ELF_CORE_EXTRA_NOTES_SIZE, was created so the size of the
additional notes could be calculated and added to the notes phdr entry.
A new macro, ELF_CORE_WRITE_EXTRA_NOTES, was created so the new notes
would be written after the existing notes.
The SPU coredump code resides in spufs. Stub functions are provided in the
kernel which are hooked into the spufs code which does the actual work via
register_arch_coredump_calls().
A new set of __spufs_<file>_read/get() functions was provided to allow the
coredump code to read from the spufs files without having to lock the
SPU context for each file read from.
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Dwayne Grant McConnell <decimal@us.ibm.com>
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
In order to add sysfs attributes to all spu's, there is a
need for a list of all available spu's. Adding the device_node
makes also sense, as it is needed for proper register access.
This patch also adds two functions to create and remove sysfs
attributes and attribute_groups to all spus.
That allows to group spu attributes in a subdirectory like:
/sys/devices/system/spu/spuX/group_name/what_ever
This will be used by cbe_thermal to group all attributes dealing with
thermal support in one directory.
Signed-off-by: Christian Krafft <krafft@de.ibm.com>
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
This adds two new flags to spu_create:
SPU_CREATE_NONSCHED: create a context that is never moved
away from an SPE once it has started running. This flag
can only be used by tasks with the CAP_SYS_NICE capability.
SPU_CREATE_ISOLATED: create a nonschedulable context that
enters isolation mode upon first run. This requires the
SPU_CREATE_NONSCHED flag.
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Remove the mostly unused variable isrc from struct spu and a forgotten
function declaration.
Signed-off-by: Geoff Levand <geoffrey.levand@am.sony.com>
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
This adds an 'object-id' file that the spe library can
use to store a pointer to its ELF object. This was
originally meant for use by oprofile, but is now
also used by the GNU debugger, if available.
In order for oprofile to find the location in an spu-elf
binary where an event counter triggered, we need a way
to identify the binary in the first place.
Unfortunately, that binary itself can be embedded in a
powerpc ELF binary. Since we can assume it is mapped into
the effective address space of the running process,
have that one write the pointer value into a new spufs
file.
When a context switch occurs, pass the user value to
the profiler so that can look at the mapped file (with
some care).
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Add the concept of a gang to spufs as a new type of object.
So far, this has no impact whatsover on scheduling, but makes
it possible to add that later.
A new type of object in spufs is now a spu_gang. It is created
with the spu_create system call with the flags argument set
to SPU_CREATE_GANG (0x2). Inside of a spu_gang, it
is then possible to create spu_context objects, which until
now was only possible at the root of spufs.
There is a new member in struct spu_context pointing to
the spu_gang it belongs to, if any. The spu_gang maintains
a list of spu_context structures that are its children.
This information can then be used in the scheduler in the
future.
There is still a bug that needs to be resolved in this
basic infrastructure regarding the order in which objects
are removed. When the spu_gang file descriptor is closed
before the spu_context descriptors, we leak the dentry
and inode for the gang. Any ideas how to cleanly solve
this are appreciated.
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
This tries to fix spufs so we have an interface closer to what is
specified in the man page for events returned in the third argument of
spu_run.
Fortunately, libspe has never been using the returned contents of that
register, as they were the same as the return code of spu_run (duh!).
Unlike the specification that we never implemented correctly, we now
require a SPU_CREATE_EVENTS_ENABLED flag passed to spu_create, in
order to get the new behavior. When this flag is not passed, spu_run
will simply ignore the third argument now.
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
This patch adds NUMA support to the the spufs scheduler.
The new arch/powerpc/platforms/cell/spufs/sched.c is greatly
simplified, in an attempt to reduce complexity while adding
support for NUMA scheduler domains. SPUs are allocated starting
from the calling thread's node, moving to others as supported by
current->cpus_allowed. Preemption is gone as it was buggy, but
should be re-enabled in another patch when stable.
The new arch/powerpc/platforms/cell/spu_base.c maintains idle
lists on a per-node basis, and allows caller to specify which
node(s) an SPU should be allocated from, while passing -1 tells
spu_alloc() that any node is allowed.
Since the patch removes the currently implemented preemptive
scheduling, it is technically a regression, but practically
all users have since migrated to this version, as it is
part of the IBM SDK and the yellowdog distribution, so there
is not much point holding it back while the new preemptive
scheduling patch gets delayed further.
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Now that get_property() returns a void *, there's no need to cast its
return value. Also, treat the return value as const, so we can
constify get_property later.
cell platform changes.
Built for cell_defconfig
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
This adds the new irq remapper core and removes the old one. Because
there are some fundamental conflicts with the old code, like the value
of NO_IRQ which I'm now setting to 0 (as per discussions with Linus),
etc..., this commit also changes the relevant platform and driver code
over to use the new remapper (so as not to cause difficulties later
in bisecting).
This patch removes the old pre-parsing of the open firmware interrupt
tree along with all the bogus assumptions it made to try to renumber
interrupts according to the platform. This is all to be handled by the
new code now.
For the pSeries XICS interrupt controller, a single remapper host is
created for the whole machine regardless of how many interrupt
presentation and source controllers are found, and it's set to match
any device node that isn't a 8259. That works fine on pSeries and
avoids having to deal with some of the complexities of split source
controllers vs. presentation controllers in the pSeries device trees.
The powerpc i8259 PIC driver now always requests the legacy interrupt
range. It also has the feature of being able to match any device node
(including NULL) if passed no device node as an input. That will help
porting over platforms with broken device-trees like Pegasos who don't
have a proper interrupt tree.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
* git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc: (139 commits)
[POWERPC] re-enable OProfile for iSeries, using timer interrupt
[POWERPC] support ibm,extended-*-frequency properties
[POWERPC] Extra sanity check in EEH code
[POWERPC] Dont look for class-code in pci children
[POWERPC] Fix mdelay badness on shared processor partitions
[POWERPC] disable floating point exceptions for init
[POWERPC] Unify ppc syscall tables
[POWERPC] mpic: add support for serial mode interrupts
[POWERPC] pseries: Print PCI slot location code on failure
[POWERPC] spufs: one more fix for 64k pages
[POWERPC] spufs: fail spu_create with invalid flags
[POWERPC] spufs: clear class2 interrupt status before wakeup
[POWERPC] spufs: fix Makefile for "make clean"
[POWERPC] spufs: remove stop_code from struct spu
[POWERPC] spufs: fix spu irq affinity setting
[POWERPC] spufs: further abstract priv1 register access
[POWERPC] spufs: split the Cell BE support into generic and platform dependant parts
[POWERPC] spufs: dont try to access SPE channel 1 count
[POWERPC] spufs: use kzalloc in create_spu
[POWERPC] spufs: fix initial state of wbox file
...
Manually resolved conflicts in:
drivers/net/phy/Makefile
include/asm-powerpc/spu.h
This patch remove 'stop_code' -- discarded member of struct spu.
It is written at initialize and interrupt, but never read
in current implementation.
Signed-off-by: Masato Noguchi <Masato.Noguchi@jp.sony.com>
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
To support muti-platform binaries the spu hypervisor accessor
routines must have runtime binding.
I removed the existing statically linked routines in spu.h
and spu_priv1_mmio.c and created new accessor routines in spu_priv1.h
that operate indirectly through an ops struct spu_priv1_ops.
spu_priv1_mmio.c contains the instance of the accessor routines
for running on raw hardware.
Signed-off-by: Geoff Levand <geoffrey.levand@am.sony.com>
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
SPUs are registered as system devices, exposing attributes through
sysfs. Since the sysdev includes a kref, we can remove the one in
struct spu (it isn't used at the moment anyway).
Currently only the interrupt source and numa node attributes are added.
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Add an nid member to the spu structure, and store the numa id of the spu there
on creation.
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Cc: Paul Mackerras <paulus@samba.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This patch is layered on top of CONFIG_SPARSEMEM
and is patterned after direct mapping of LS.
This patch allows mmap() of the following regions:
"mfc", which represents the area from [0x3000 - 0x3fff];
"cntl", which represents the area from [0x4000 - 0x4fff];
"signal1" which begins at offset 0x14000; "signal2" which
begins at offset 0x1c000.
The signal1 & signal2 files may be mmap()'d by regular user
processes. The cntl and mfc file, on the other hand, may
only be accessed if the owning process has CAP_SYS_RAWIO,
because they have the potential to confuse the kernel
with regard to parallel access to the same files with
regular file operations: the kernel always holds a spinlock
when accessing registers in these areas to serialize them,
which can not be guaranteed with user mmaps,
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
