Commit Graph

32 Commits

Author SHA1 Message Date
Aneesh Kumar K.V b42279f016 powerpc/mm/nohash: MM_SLICE is only used by book3s 64
BOOKE code is dead code as per the Kconfig details. So make it simpler
by enabling MM_SLICE only for book3s_64. The changes w.r.t nohash is just
removing deadcode. W.r.t ppc64, 4k without hugetlb will now enable MM_SLICE.
But that is good, because we reduce one extra variant which probably is not
getting tested much.

Reviewed-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2017-03-31 23:09:47 +11:00
Sebastian Andrzej Siewior da3ed6519b powerpc/mmu nohash: Convert to hotplug state machine
Install the callbacks via the state machine.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: rt@linutronix.de
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: linuxppc-dev@lists.ozlabs.org
Link: http://lkml.kernel.org/r/20160818125731.27256-17-bigeasy@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2016-09-06 18:30:27 +02:00
Aneesh Kumar K.V 62ccf5bf1f powerpc/mm/slice: Remove slice_mm_new_context()
The usage in mm mmu_context_nohash.c is bogus, because we set the
context.id value to MMU_NO_CONTEXT 4 lines previously in the same
function, meaning slice_mm_new_context() will always be true.

The book3s 64 usage was removed in the previous commit. So remove it as
unused.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2016-05-11 21:54:00 +10:00
Aneesh Kumar K.V d2adba3fd1 powerpc/mm: Abstraction for switch_mmu_context()
How we switch MMU context differs between hash and radix. For hash we
need to switch the SLB details and for radix we need to switch the PID
SPR.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2016-05-01 18:33:04 +10:00
LEROY Christophe debddd95ec powerpc/8xx: reduce pressure on TLB due to context switches
For nohash powerpc, when we run out of contexts, contexts are freed by stealing
used contexts in-turn. When a victim has been selected, the associated TLB
entries are freed using _tlbil_pid(). Unfortunatly, on the PPC 8xx, _tlbil_pid()
does a tlbia, hence flushes ALL TLB entries and not only the one linked to the
stolen context. Therefore, as implented today, at each task switch requiring a
new context, all entries are flushed.

This patch modifies the implementation so that when running out of contexts, all
contexts get freed at once, hence dividing the number of calls to tlbia by 16.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Scott Wood <scottwood@freescale.com>
2015-01-29 21:51:06 -06:00
Michael Ellerman e39f223fc9 powerpc: Remove more traces of bootmem
Although we are now selecting NO_BOOTMEM, we still have some traces of
bootmem lying around. That is because even with NO_BOOTMEM there is
still a shim that converts bootmem calls into memblock calls, but
ultimately we want to remove all traces of bootmem.

Most of the patch is conversions from alloc_bootmem() to
memblock_virt_alloc(). In general a call such as:

  p = (struct foo *)alloc_bootmem(x);

Becomes:

  p = memblock_virt_alloc(x, 0);

We don't need the cast because memblock_virt_alloc() returns a void *.
The alignment value of zero tells memblock to use the default alignment,
which is SMP_CACHE_BYTES, the same value alloc_bootmem() uses.

We remove a number of NULL checks on the result of
memblock_virt_alloc(). That is because memblock_virt_alloc() will panic
if it can't allocate, in exactly the same way as alloc_bootmem(), so the
NULL checks are and always have been redundant.

The memory returned by memblock_virt_alloc() is already zeroed, so we
remove several memsets of the result of memblock_virt_alloc().

Finally we convert a few uses of __alloc_bootmem(x, y, MAX_DMA_ADDRESS)
to just plain memblock_virt_alloc(). We don't use memblock_alloc_base()
because MAX_DMA_ADDRESS is ~0ul on powerpc, so limiting the allocation
to that is pointless, 16XB ought to be enough for anyone.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2014-11-19 21:41:51 +11:00
Michael Ellerman cd68098bce powerpc: Clean up MMU_FTRS_A2 and MMU_FTR_TYPE_3E
In fb5a515704 "powerpc: Remove platforms/wsp and associated pieces",
we removed the last user of MMU_FTRS_A2. So remove it.

MMU_FTRS_A2 was the last user of MMU_FTR_TYPE_3E, so remove it also.
This leaves some unreachable code in mmu_context_nohash.c, so remove
that also.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2014-07-11 12:55:05 +10:00
Paul Gortmaker 061d19f279 powerpc: Delete __cpuinit usage from all users
The __cpuinit type of throwaway sections might have made sense
some time ago when RAM was more constrained, but now the savings
do not offset the cost and complications.  For example, the fix in
commit 5e427ec2d0 ("x86: Fix bit corruption at CPU resume time")
is a good example of the nasty type of bugs that can be created
with improper use of the various __init prefixes.

After a discussion on LKML[1] it was decided that cpuinit should go
the way of devinit and be phased out.  Once all the users are gone,
we can then finally remove the macros themselves from linux/init.h.

This removes all the powerpc uses of the __cpuinit macros.  There
are no __CPUINIT users in assembly files in powerpc.

[1] https://lkml.org/lkml/2013/5/20/589

Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Josh Boyer <jwboyer@gmail.com>
Cc: Matt Porter <mporter@kernel.crashing.org>
Cc: Kumar Gala <galak@kernel.crashing.org>
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2013-07-01 11:10:36 +10:00
Scott Wood 39a421ff0b powerpc/mm/nohash: Ignore NULL stale_map entries
This happens with threads that are offline due to CPU hotplug
(including threads that were never "plugged in" to begin with because
SMT is disabled).

Signed-off-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2013-06-20 16:55:10 +10:00
Anton Vorontsov 73863ab028 powerpc: use clear_tasks_mm_cpumask()
Current CPU hotplug code has some task->mm handling issues:

1. Working with task->mm w/o getting mm or grabing the task lock is
   dangerous as ->mm might disappear (exit_mm() assigns NULL under
   task_lock(), so tasklist lock is not enough).

   We can't use get_task_mm()/mmput() pair as mmput() might sleep,
   so we must take the task lock while handle its mm.

2. Checking for process->mm is not enough because process' main
   thread may exit or detach its mm via use_mm(), but other threads
   may still have a valid mm.

   To fix this we would need to use find_lock_task_mm(), which would
   walk up all threads and returns an appropriate task (with task
   lock held).

clear_tasks_mm_cpumask() has all the issues fixed, so let's use it.

Suggested-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-05-31 17:49:29 -07:00
Becky Bruce 41151e77a4 powerpc: Hugetlb for BookE
Enable hugepages on Freescale BookE processors.  This allows the kernel to
use huge TLB entries to map pages, which can greatly reduce the number of
TLB misses and the amount of TLB thrashing experienced by applications with
large memory footprints.  Care should be taken when using this on FSL
processors, as the number of large TLB entries supported by the core is low
(16-64) on current processors.

The supported set of hugepage sizes include 4m, 16m, 64m, 256m, and 1g.
Page sizes larger than the max zone size are called "gigantic" pages and
must be allocated on the command line (and cannot be deallocated).

This is currently only fully implemented for Freescale 32-bit BookE
processors, but there is some infrastructure in the code for
64-bit BooKE.

Signed-off-by: Becky Bruce <beckyb@kernel.crashing.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2011-09-20 09:19:40 +10:00
Benjamin Herrenschmidt bd49178109 powerpc: Add TLB size detection for TYPE_3E MMUs
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2011-04-27 13:02:10 +10:00
Michael Ellerman f5be2dc0bd powerpc/nohash: Allocate stale_map[cpu] on CPU_UP_PREPARE not CPU_ONLINE
Currently we allocate the stale_map for a cpu when it comes online,
this leaves open a small window where a process can be scheduled
on the cpu before the stale_map is allocated. Instead allocate
the stale_map at CPU_UP_PREPARE time, that way it will be always
available before tasks start running.

It is possible the cpu fails to come up, in which case we should free
the stale_map, so add a CPU_UP_CANCELED case to do that.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2011-04-20 17:01:18 +10:00
Vaidyanathan Srinivasan 99d8670525 powerpc: Cleanup APIs for cpu/thread/core mappings
These APIs take logical cpu number as input
Change cpu_first_thread_in_core() to cpu_first_thread_sibling()
Change cpu_last_thread_in_core() to cpu_last_thread_sibling()

These APIs convert core number (index) to logical cpu/thread numbers
Add cpu_first_thread_of_core(int core)
Changed cpu_thread_to_core() to cpu_core_index_of_thread(int cpu)

The goal is to make 'threads_per_core' accessible to the
pseries_energy module.  Instead of making an API to read
threads_per_core, this is a higher level wrapper function to
convert from logical cpu number to core number.

The current APIs cpu_first_thread_in_core() and
cpu_last_thread_in_core() returns logical CPU number while
cpu_thread_to_core() returns core number or index which is
not a logical CPU number.  The new APIs are now clearly named to
distinguish 'core number' versus first and last 'logical cpu
number' in that core.

The new APIs cpu_{first,last}_thread_sibling() work on
logical cpu numbers.  While cpu_first_thread_of_core() and
cpu_core_index_of_thread() work on core index.

Example usage:  (4 threads per core system)

cpu_first_thread_sibling(5) = 4
cpu_last_thread_sibling(5) = 7
cpu_core_index_of_thread(5) = 1
cpu_first_thread_of_core(1) = 4

cpu_core_index_of_thread() is used in cpu_to_drc_index() in the
module and cpu_first_thread_of_core() is used in
drc_index_to_cpu() in the module.

Make API changes to few callers.  Export symbols for use in modules.

Signed-off-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2010-11-29 15:48:19 +11:00
Matthew McClintock 0d35e1620d powerpc/mm: Assume first cpu is boot_cpuid not 0
arch/powerpc/mm/mmu_context_nohash.c assumes the boot cpu
will always have smp_processor_id() == 0. This patch fixes
that assumption

Signed-off-by: Matthew McClintock <msm@freescale.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2010-09-02 14:07:34 +10:00
Dave Kleikamp e7f75ad01d powerpc/47x: Base ppc476 support
This patch adds the base support for the 476 processor.  The code was
primarily written by Ben Herrenschmidt and Torez Smith, but I've been
maintaining it for a while.

The goal is to have a single binary that will run on 44x and 47x, but
we still have some details to work out.  The biggest is that the L1 cache
line size differs on the two platforms, but it's currently a compile-time
option.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Torez Smith  <lnxtorez@linux.vnet.ibm.com>
Signed-off-by: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>
2010-05-05 09:11:10 -04:00
Tejun Heo 5a0e3ad6af 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: Tejun Heo <tj@kernel.org>
Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
2010-03-30 22:02:32 +09:00
Thomas Gleixner be833f3371 powerpc: Convert context_lock to raw_spinlock
context_lock needs to be a real spinlock in RT. Convert it to
raw_spinlock.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2010-02-19 14:52:30 +11:00
Yang Li f04b10cddb powerpc/mm: Fix typo of cpumask_clear_cpu()
The function name of cpumask_clear_cpu was not correct. Fortunately
nobody uses that code with hotplug yet :-)

Reported-by: Jin Qing <b24347@freescale.com>
Signed-off-by: Li Yang <leoli@freescale.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2009-12-18 14:54:27 +11:00
Benjamin Herrenschmidt f1167fb318 powerpc/mm: Remove debug context clamping from nohash code
I inadvertently left that debug code enabled, causing the number of
contexts to be clamped to 31 which is going to slow things down on
4xx and just plain breaks 8xx

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2009-11-05 16:41:59 +11:00
Kumar Gala 67050b5c3e powerpc/mm: Fix switch_mmu_context to iterate of the proper list of cpus
Introduced a temporary variable into our iterating over the list cpus
that are threads on the same core.  For some reason Ben forgot how for
loops work.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2009-08-20 10:25:12 +10:00
Benjamin Herrenschmidt fcce810986 powerpc/mm: Add HW threads support to no_hash TLB management
The current "no hash" MMU context management code is written with
the assumption that one CPU == one TLB. This is not the case on
implementations that support HW multithreading, where several
linux CPUs can share the same TLB.

This adds some basic support for this to our context management
and our TLB flushing code.

It also cleans up the optional debugging output a bit

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2009-08-20 10:12:37 +10:00
Kumar Gala 5156ddce6c powerpc/mm: Fix SMP issue with MMU context handling code
In switch_mmu_context() if we call steal_context_smp() to get a context
to use we shouldn't fall through and than call steal_context_up().  Doing
so can be problematic in that the 'mm' that steal_context_up() ends up
using will not get marked dirty in the stale_map[] for other CPUs that
might have used that mm.  Thus we could end up with stale TLB entries in
the other CPUs that can cause all kinda of havoc.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
2009-07-29 23:05:43 -05:00
Michael Ellerman a1ac38ab98 powerpc: Use pr_devel() in arch/powerpc/mm/mmu_context_nohash.c
pr_debug() can now result in code being generated even when DEBUG
is not defined. That's not really desirable in some places.

With CONFIG_DYNAMIC_DEBUG=y:

size before:
   text	   data	    bss	    dec	    hex	filename
   1508	     48	     28	   1584	    630	powerpc/mm/mmu_context_nohash.o

size after:
   text	   data	    bss	    dec	    hex	filename
   1088	      0	     28	   1116	    45c	powerpc/mm/mmu_context_nohash.o

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2009-07-08 13:50:22 +10:00
Benjamin Herrenschmidt b46b6942b3 powerpc/mm: Fix a AB->BA deadlock scenario with nohash MMU context lock
The MMU context_lock can be taken from switch_mm() while the
rq->lock is held. The rq->lock can also be taken from interrupts,
thus if we get interrupted in destroy_context() with the context
lock held and that interrupt tries to take the rq->lock, there's
a possible deadlock scenario with another CPU having the rq->lock
and calling switch_mm() which takes our context lock.

The fix is to always ensure interrupts are off when taking our
context lock. The switch_mm() path is already good so this fixes
the destroy_context() path.

While at it, turn the context lock into a new style spinlock.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2009-06-09 16:43:04 +10:00
Benjamin Herrenschmidt 3035c8634f powerpc/mm: Fix some SMP issues with MMU context handling
This patch fixes a couple of issues that can happen as a result
of steal_context() dropping the context_lock when all possible
PIDs are ineligible for stealing (hopefully an extremely hard to
hit occurence).

This case exposes the possibility of a stale context_mm[] entry
to be seen since destroy_context() doesn't clear it and the free
map isn't re-tested. It also means steal_context() will not notice
a context freed while the lock was help, thus possibly trying to
steal a context when a free one was available.

This fixes it by always returning to the caller from steal_context
when it dropped the lock with a return value that causes the
caller to re-samble the number of free contexts, along with
properly clearing the context_mm[] array for destroyed contexts.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2009-06-09 16:42:21 +10:00
Hideo Saito 8e35961b57 powerpc/mm: Fix broken MMU PID stealing on !SMP
The recent rework of the MMU PID handling for non-hash CPUs has a
subtle bug in the !SMP "optimized" variant of the PID stealing
function.  It clears the PID in the mm context before it calls
local_flush_tlb_mm(). However, the later will not flush anything
if the PID in the context is clear...

Signed-off-by: Hideo Saito <hsaito.ppc@gmail.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2009-05-26 13:46:49 +10:00
Benjamin Herrenschmidt ff7c660092 powerpc/mm: Fix printk type warning in mmu_context_nohash
We need to use %zu instead of %d when printing a sizeof()

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2009-03-24 13:47:34 +11:00
Rusty Russell 56aa4129e8 cpumask: Use mm_cpumask() wrapper instead of cpu_vm_mask
Makes code futureproof against the impending change to mm->cpu_vm_mask.

It's also a chance to use the new cpumask_ ops which take a pointer
(the older ones are deprecated, but there's no hurry for arch code).

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2009-03-24 13:47:29 +11:00
Benjamin Herrenschmidt 7752035180 powerpc/mm: Runtime allocation of mmu context maps for nohash CPUs
This makes the MMU context code used for CPUs with no hash table
(except 603) dynamically allocate the various maps used to track
the state of contexts.

Only the main free map and CPU 0 stale map are allocated at boot
time.  Other CPU maps are allocated when those CPUs are brought up
and freed if they are unplugged.

This also moves the initialization of the MMU context management
slightly later during the boot process, which should be fine as
it's really only needed when userland if first started anyways.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
2008-12-21 14:21:16 +11:00
Benjamin Herrenschmidt 2ca8cf7389 powerpc/mm: Rework context management for CPUs with no hash table
This reworks the context management code used by 4xx,8xx and
freescale BookE.  It adds support for SMP by implementing a
concept of stale context map to lazily flush the TLB on
processors where a context may have been invalidated.  This
also contains the ground work for generalizing such lazy TLB
flushing by just picking up a new PID and marking the old one
stale.  This will be implemented later.

This is a first implementation that uses a global spinlock.

Ideally, we should try to get at least the fast path (context ID
already assigned) lockless or limited to a per context lock,
but for now this will do.

I tried to keep the UP case reasonably simple to avoid adding
too much overhead to 8xx which does a lot of context stealing
since it effectively has only 16 PIDs available.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
2008-12-21 14:21:15 +11:00
Benjamin Herrenschmidt 5e696617c4 powerpc/mm: Split mmu_context handling
This splits the mmu_context handling between 32-bit hash based
processors, 64-bit hash based processors and everybody else.  This is
preliminary work for adding SMP support for BookE processors.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
2008-12-21 14:21:15 +11:00