Commit Graph

478 Commits

Author SHA1 Message Date
Richard Purdie
756c7b7489 [ARM] 3113/1: PXA: Allow machines to override (and also reuse) pxa pm functions
Patch from Richard Purdie

Update the PXA pm.c file to allow machines (such as the Sharp
Zaurus) to override the standard pm functions but reuse/wrap them
where needed.

The init call is made slightly earlier to give machine code an init
level to override them in removing any race.

Signed-off-by: Richard Purdie
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-06 15:03:23 +00:00
Nicolas Pitre
b7ec479553 [ARM] 3115/1: small optimizations to exception vector entry code
Patch from Nicolas Pitre

Since we know the value of cpsr on entry, we can replace the bic+orr with
a single eor.  Also remove a possible result delay (at least on XScale).

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-06 14:42:37 +00:00
Lennert Buytenhek
7240f1f183 [ARM] 3114/1: use ixp2000_reg_wrb in ixp2000 uengine loader
Patch from Lennert Buytenhek

Make the uengine loader use ixp2000_reg_wrb in the right places.

Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-06 14:34:13 +00:00
Alessandro Zummo
84613387cb [ARM] 3089/1: ixp4xx AHB/PCI endianness fix
Patch from Alessandro Zummo

  This patch fixes AHB/PCI endianness problems when the
 processor is in little-endian mode.

 The patch configures the CSR register closely following the directives
 in [1], paragraph 4.1, page 19.

 According to the considerations in [1], page 11, while the AHB bus
 supports both endian modes, on the IXP4XX it always uses big-endian.

 The PCI bus is connected to the South AHB. A wrong setting in the CSR
 register will thus cause a malfunctional PCI bus.

 A schematic diagram of the bus interconnections on the IXP4XX
 can be found in [1], page 18.

 The patch has been verified to work on the NSLU2 in
 both LE and BE modes.

 The author is Peter Korsgaard.

 [1] Intel® IXP4XX Product Line of Network Processors and IXC1100
 Control Plane Processor:
 Understanding Big Endian and Little Endian Modes

 http://www.intel.com/design/network/applnots/25423701.pdf

Signed-off-by: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Deepak Saxena <dsaxena@plexity.net>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-06 14:34:12 +00:00
Dirk Opfer
8459c159f7 [ARM] 3088/1: PXA: Add machine support for the Sharp SL-6000x series of PDAs
Patch from Dirk Opfer

This patch adds basic machine support for the Sharp SL-6000x (Tosa) PDAs.

Signed-off-by: Dirk Opfer
Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-06 14:27:52 +00:00
Russell King
d56c524afa [PATCH] ARM: Reverted 2918/1: [update] Base port of Comdial MP1000 platfrom
No longer maintained
2005-11-04 17:28:34 +00:00
Nicolas Pitre
30c2f90b68 [ARM] 3097/1: change library link ordering
Patch from Nicolas Pitre

We have an optimized sha1 routine (arch/arm/lib/sha1.S) meant to
override the generic one in lib/sha1.c.

Unfortunately lib/lib.a is listed _before_ arch/arm/lib/lib.a in the
link argument list and therefore the architecture specific lib functions
are not picked up before the generic versions.

This patch is a quick fix to change that ordering for ARM.  Here's what
the kbuild maintainer had to say about it (was also CC'd on lkml):

On Wed, 2 Nov 2005, Sam Ravnborg wrote:
> This looks like an obvious way to achive correct ordering.
> We could change it so arch defines always took precedence but
> the above is so simple that it is not worth the effort.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-04 17:17:30 +00:00
Todd Poynor
74ec71e161 [ARM] 3087/1: PXA2xx flash platform device conversion
Patch from Todd Poynor

Add platform devices for flash to Lubbock and Mainstone board files.
Once in place, the two existing mtd map drivers for the boards will be
converted to use a single pxa2xx map driver in the linux-mtd tree.
Take 4: flash_platform_data .map_name vs. .name cleaned up, resync with
merged irda patch context.

Signed-off-by: Todd Poynor <tpoynor@mvista.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-04 17:15:45 +00:00
Dave Jiang
7866f64928 [ARM] 3086/1: ixp2xxx error irq handling
Patch from Dave Jiang

This provides support for IXP2xxx error interrupt handling. Previously there was a patch to remove this (although the original stuff was broken). Well, now the error bits are needed again. These are used extensively by the micro-engine drivers according to Deepak and also we will need it for the new EDAC code that Alan Cox is trying to push into the main kernel.

Re-submit of 3072/1, generated against git tree pulled today. AFAICT, this git tree pulled in all the ARM changes that's in arm.diff. Please let me know if there are additional changes. Thx!

Signed-off-by: Dave Jiang <djiang@mvista.com>
Signed-off-by: Deepak Saxena <dsaxena@plexity.net>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-04 17:15:44 +00:00
Nicolas Pitre
73f0f7c79b [ARM] 3094/1: remove PLD stuff from old uaccess code
Patch from Nicolas Pitre

ARM processors that have pld instructions are not using those copy_user
implementation anymore.  Let's remove the useless PLD lines which were
half wrong anyway.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-04 17:15:43 +00:00
Deepak Saxena
8b5f4f06ee [ARM] Fix IXDP2x01 config files
IXDP2401 config file has wrong baudrate and both boards have 3 UARTs.

Signed-off-by: Deepak Saxena <dsaxena@plexity.net>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-03 21:05:39 +00:00
Russell King
5f8b1178e2 [ARM] Merge SMP tree 2005-11-03 21:02:39 +00:00
Nicolas Pitre
24bcc2f46c [ARM] 3092/1: remove excessive print format padding
Patch from Nicolas Pitre

Using a llx format to print addresses that might possibly be (only) 36
bits wide make sense.  However making it a zero padded 16 char wide
field is a bit excessive and useless.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-03 20:40:50 +00:00
Russell King
4a5f79e7e6 [ARM SMP] Add configuration option for ARMv6K processors
The 'K' extension adds several new instructions to the ARMv6 ISA
which are primerily useful for SMP.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-03 15:48:21 +00:00
Russell King
0dcc7474b2 [ARM] Add Realview default configuration file
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-03 10:17:44 +00:00
Russell King
ca82d85bc2 [ARM] Fix more 3016/1 breakage
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-03 10:06:35 +00:00
Russell King
a054a81159 [ARM SMP] Add hotplug CPU infrastructure
This patch adds the infrastructure to support hotplug CPU on ARM
platforms.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-02 22:24:33 +00:00
Russell King
273c2cdb2b [ARM SMP] Fix a couple of warnings
Use *cpus_addr() to display the mask of pending/to be called CPUs.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-02 21:54:14 +00:00
Russell King
71f512e897 [ARM SMP] Track CPU idle threads
Track the idle thread task_struct for each CPU.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-02 21:51:40 +00:00
Russell King
1ffedce7e8 [ARM] Fix Realview machine for patch 3016/1
3016/1 changed the map_desc structure to take a PFN instead of a
physical address.  Fixup Realview machine support for this change.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-02 14:14:37 +00:00
Russell King
6bf7bd6967 [ARM] Fix mm initialisation with write buffered write allocate caches
It seems that without the extra tlb flush, we may end up faulting
during the early kernel initialisation because the TLB can't see
the updated page tables.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-02 14:11:35 +00:00
Linus Torvalds
7f36b1e958 Merge master.kernel.org:/home/rmk/linux-2.6-arm 2005-11-01 21:32:14 -08:00
Deepak Saxena
73ee723e4c [ARM] 3081/1: Remove GTWX5715 from ixp4xx_defconfig
Patch from Deepak Saxena

CONFIG_MACH_GTWX5715 hardcodes the machine type in head-xscale.S so we
can no longer boot on any other machine types. The proper fix would be
to remove the hardcoding, but that machine is an off-the-shelf system
and most users won't have access to the bootloader. :(

Signed-off-by: Deepak Saxena <dsaxena@plexity.net>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-01 22:32:12 +00:00
Lennert Buytenhek
d01e8897fc [ARM] 3052/1: add ixp2000 microcode loader
Patch from Lennert Buytenhek

This patch adds a microcode loader for the ixp2000 architecture.

The ixp2000 is an xscale-based CPU with a number of additional small
CPUs ('microengines') on die that can be programmed to do various
things.  Depending on the ixp2000 model, there are between 2 and 16
microengines.

This code provides an API that allows configuring the microengines,
loading code into them, and starting and stopping them and reading
out a number of status registers, and is used by the microengine
network driver that was recently announced to netdev.

Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org>
Signed-off-by: Deepak Saxena <dsaxena@plexity.net>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-01 19:53:50 +00:00
Nicolas Pitre
fadab0943d [ARM] 2948/1: new preemption safe copy_{to|from}_user implementation
Patch from Nicolas Pitre

This patch provides a preemption safe implementation of copy_to_user
and copy_from_user based on the copy template also used for memcpy.
It is enabled unconditionally when CONFIG_PREEMPT=y.  Otherwise if the
configured architecture is not ARMv3 then it is enabled as well as it
gives better performances at least on StrongARM and XScale cores.  If
ARMv3 is not too affected or if it doesn't matter too much then
uaccess.S could be removed altogether.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-01 19:52:24 +00:00
Nicolas Pitre
7549423000 [ARM] 2947/1: copy template with new memcpy/memmove
Patch from Nicolas Pitre

This patch provides a new implementation for optimized memory copy
functions on ARM.  It is made of two levels: a template that consists of
the core copy code and separate files that define macros to be used with
the core code depending on the type of copy needed. This allows for best
performances while sharing the same core for implementing memcpy(),
copy_from_user() and copy_to_user() for instance.

Two reasons for this work:

1) the current copy_to_user/copy_from_user implementation assumes no
   task switch will ever occur in the middle of each copied page making
   it completely unsafe with CONFIG_PREEMPT=y.

2) current copy implementations are measurably suboptimal and optimizing
   different implementations separately is a pain and more opportunities
   for bugs.

The reason for (1) is the fact that copy inside user pages are performed
with the ldm instruction which has no mean for testing user protections
and could possibly race with process preemption bypassing the COW mechanism
for example.  This is a longstanding issue that we said ought to be fixed
for about two years now.  The solution is to substitute those ldm insns
with a series of ldrt or strt insns to enforce user memory protection.
At least on StrongARM and XScale cores the ldm is not faster than the
equivalent ldr/str insns with a warm i-cache so there is no measurable
performance degradation with that change. The fact that the copy code is
a template makes it pretty easy to reuse the same core code as for memcpy
and benefit from the same performance optimizations.

Now (2) is best demonstrated with actual throughput measurements.
First, here is a summary of memcopy tests performed on a StrongARM core:

	PTR alignment	buffer size	kernel version	this version
	------------------------------------------------------------
	  aligned	     32		 59.73		107.43
	unaligned	     32		 61.31		 74.72
	  aligned	    100		132.47		136.15
	unaligned	    100	    	103.84		123.76
	  aligned	   4096		130.67		130.80
	unaligned	   4096	    	130.68		130.64
	  aligned	1048576		 68.03		68.18
	unaligned	1048576		 68.03		68.18

The buffer size is in bytes and the measured speed in MB/s.  The copy
was performed repeatedly with given buffer and throughput averaged over
3 seconds.

Here we can see that the current kernel version has a higher entry cost
that shows up with small buffers.  As buffer size grows both implementation
converge to the same throughput.

Now here's the exact same test performed on an XScale core (PXA255):

	PTR alignment	buffer size	kernel version	this version
	------------------------------------------------------------
	  aligned	     32		 46.99		 77.58
	unaligned	     32		 53.61		 59.59
	  aligned	    100		107.19		136.59
	unaligned	    100		 83.61		 97.58
	  aligned	   4096		129.13		129.98
	unaligned	   4096		128.36		128.53
	  aligned	1048576		 53.76		 59.41
	unaligned	1048576		 33.67		 56.96

Again we can see the entry setup cost being higher for the current kernel
before getting to the main copy loop.  Then throughput results converge
as long as the buffer remains in the cache. Then the 1MB case shows more
differences probably due to better pld placement and/or less instruction
interlocks in this proposed implementation.

Disclaimer: The PXA system was running with slower clocks than the
StrongARM system so trying to infer any conclusion by comparing those
separate sets of results side by side would be completely inappropriate.

So...  What this patch does is to replace both memcpy and memmove with
an implementation based on the provided copy code template.  The memmove
code is kept separate since it is used only if the memory areas involved
do overlap in which case the code is a transposition of the template but
with the copy occurring in the opposite direction (trying to fit that
mode into the template turned it into a mess not worth it for memmove
alone).  And obviously both memcpy and memmove were tested with all kinds
of pointer alignments and buffer sizes to exercise all code paths for
correctness.

The next patch will provide the now trivial replacement implementation
copy_to_user and copy_from_user.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-01 19:52:23 +00:00
Nicolas Pitre
a0c6fdb987 [ARM] 2946/2: split --arch_clear_user() out of lib/uaccess.S
Patch from Nicolas Pitre

Required for future enhancement patches.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-01 19:52:22 +00:00
David Brownell
85eb226c44 [ARM] 3078/1: lubbock platform updates, mostly mmc detection
Patch from David Brownell

Lubbock updates:

  * Provide an address for the SMC91x chip that doesn't generate
    a boot-time warning (matching the EEPROM).

  * Update MMC support to (a) detect card insert/remove, and
    (b) report the readonly switch setting for SD cards.

Previously, MMC/SD cards had to be present at boot time else they
couldn't be detected.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-01 19:44:30 +00:00
Ben Dooks
e838ffc2e5 [ARM] 3071/1: RX3715 - add lcd/fb platform setup
Patch from Ben Dooks

Platform data for the LCD/framebuffer driver for
the RX3715 LCD panel.

Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-01 19:44:28 +00:00
Lennert Buytenhek
fa87cedd4e [ARM] 3065/1: ixp2000 typo and whitespace fixes
Patch from Lennert Buytenhek

Misc ixp2000 typo and whitespace fixes.

Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org>
Signed-off-by: Deepak Saxena <dsaxena@plexity.net>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-01 19:44:27 +00:00
Lennert Buytenhek
e9b72e43d9 [ARM] 3064/1: start using ixp2000_reg_wrb
Patch from Lennert Buytenhek

Switch the users of ixp2000_reg_write that depend on writes being
flushed out of the write buffer by the time that function returns
over to ixp2000_reg_wrb.

When using XCB=101, writes to the same functional unit are still
guaranteed to complete in order, so we only need to protect against:
- reordering of writes to different functional units
- masking an interrupt and then reenabling the IRQ bit in CPSR

Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org>
Signed-off-by: Deepak Saxena <dsaxena@plexity.net>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-01 19:44:26 +00:00
Lennert Buytenhek
a6f1063b38 [ARM] 3062/1: map in various enp2611 peripherals for the ixp2000 netdev driver
Patch from Lennert Buytenhek

The enp2611 version of the ixp2000 netdev driver needs to be able to
access a number of on-board peripherals.  ioremap() is not suitable
for this, as that will cause XCB=000 mappings to be done, which will
make the cpu susceptible to crashing on ixp2400 erratum #66.  Properly
aligned iotable mappings with MT_IXP2000_DEVICE will cause section
mappings with XCB=101 to be done, which is safe.

Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org>
Signed-off-by: Deepak Saxena <dsaxena@plexity.net>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-01 19:44:24 +00:00
Russell King
37bb30e86b [ARM] Convert EBSA110 network driver to a platform driver
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-10-31 17:14:57 +00:00
Russell King
1be7228da2 [ARM] Fixup platform device.h includes for realview board
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-10-31 16:57:06 +00:00
Linus Torvalds
4fd5f8267d Merge master.kernel.org:/home/rmk/linux-2.6-drvmodel
Manual #include fixups for clashes - there may be some unnecessary
2005-10-31 07:32:56 -08:00
Catalin Marinas
8ad68bbf7a [ARM] Add support for ARM RealView board
Support for RealView EB.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-10-31 14:25:02 +00:00
Linus Torvalds
1480d0a31d Merge master.kernel.org:/home/rmk/linux-2.6-arm 2005-10-30 17:48:00 -08:00
Tim Schmielau
4e57b68178 [PATCH] fix missing includes
I recently picked up my older work to remove unnecessary #includes of
sched.h, starting from a patch by Dave Jones to not include sched.h
from module.h. This reduces the number of indirect includes of sched.h
by ~300. Another ~400 pointless direct includes can be removed after
this disentangling (patch to follow later).
However, quite a few indirect includes need to be fixed up for this.

In order to feed the patches through -mm with as little disturbance as
possible, I've split out the fixes I accumulated up to now (complete for
i386 and x86_64, more archs to follow later) and post them before the real
patch.  This way this large part of the patch is kept simple with only
adding #includes, and all hunks are independent of each other.  So if any
hunk rejects or gets in the way of other patches, just drop it.  My scripts
will pick it up again in the next round.

Signed-off-by: Tim Schmielau <tim@physik3.uni-rostock.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-30 17:37:32 -08:00
Thomas Gleixner
ecea8d19c9 [PATCH] jiffies_64 cleanup
Define jiffies_64 in kernel/timer.c rather than having 24 duplicated
defines in each architecture.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-30 17:37:25 -08:00
Christoph Hellwig
dfb7dac3af [PATCH] unify sys_ptrace prototype
Make sure we always return, as all syscalls should.  Also move the common
prototype to <linux/syscalls.h>

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-30 17:37:20 -08:00
Deepak Saxena
5ecdb02c9d [ARM] fix ixp2x00 defconfig NR_UARTS options
IXDP2[48]00 have only 1 UART on the board.

Signed-off-by: Deepak Saxena <dsaxena@plexity.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-10-30 23:36:37 +00:00
Nicolas Pitre
f741a1aab5 [ARM] 3049/1: More optimized libgcc functions
Patch from Nicolas Pitre

This patch gets rid of the last C implementations of needed libgcc
functions for the kernel, replacing them with optimized assembly
versions.

Those functions are:

__ashldi3
__ashrdi3
__lshrdi3
__muldi3
__ucmpdi2

The first 3 were lifted from gcc, the other two were written from scratch.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-10-30 23:08:03 +00:00
Russell King
cb7610d018 [ARM] Clean up dmabounce
Encapsulate pool data into dmabounce_pool.  Only account successful
allocations.  Use dma_mapping_error().

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-10-30 21:12:08 +00:00
Russell King
b4c2803ca8 [ARM] Make v6 copypage function static and cleanup pgprots
We know what pgprot we're going to use, so don't #define it.  Also,
since we select the nonaliasing/aliasing copypage implementation at
run time, there's no point having it globally visible.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-10-30 19:03:21 +00:00
Russell King
d362979aa2 [ARM] Re-organise die()
Provide __die() which can be called from various contexts to provide
an oops report.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-10-30 19:01:43 +00:00
Richard Purdie
dc07845d0c [ARM] 3069/1: Add spitz irda platform support
Patch from Richard Purdie

Add spitz irda platform support

Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-10-30 14:50:25 +00:00
Richard Purdie
ca1140b57d [ARM] 3068/1: Add corgi irda platform support
Patch from Richard Purdie

Add corgi irda platform support

Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-10-30 14:38:53 +00:00
Richard Purdie
8e4b8715d8 [ARM] 3067/1: Add poodle irda platform support
Patch from Richard Purdie

Add poodle irda platform support

Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-10-30 14:38:52 +00:00
Hugh Dickins
4c21e2f244 [PATCH] mm: split page table lock
Christoph Lameter demonstrated very poor scalability on the SGI 512-way, with
a many-threaded application which concurrently initializes different parts of
a large anonymous area.

This patch corrects that, by using a separate spinlock per page table page, to
guard the page table entries in that page, instead of using the mm's single
page_table_lock.  (But even then, page_table_lock is still used to guard page
table allocation, and anon_vma allocation.)

In this implementation, the spinlock is tucked inside the struct page of the
page table page: with a BUILD_BUG_ON in case it overflows - which it would in
the case of 32-bit PA-RISC with spinlock debugging enabled.

Splitting the lock is not quite for free: another cacheline access.  Ideally,
I suppose we would use split ptlock only for multi-threaded processes on
multi-cpu machines; but deciding that dynamically would have its own costs.
So for now enable it by config, at some number of cpus - since the Kconfig
language doesn't support inequalities, let preprocessor compare that with
NR_CPUS.  But I don't think it's worth being user-configurable: for good
testing of both split and unsplit configs, split now at 4 cpus, and perhaps
change that to 8 later.

There is a benefit even for singly threaded processes: kswapd can be attacking
one part of the mm while another part is busy faulting.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 21:40:42 -07:00
Hugh Dickins
69b0475456 [PATCH] mm: arm ready for split ptlock
Prepare arm for the split page_table_lock: three issues.

Signal handling's preserve and restore of iwmmxt context currently involves
reading and writing that context to and from user space, while holding
page_table_lock to secure the user page(s) against kswapd.  If we split the
lock, then the structure might span two pages, secured by to read into and
write from a kernel stack buffer, copying that out and in without locking (the
structure is 160 bytes in size, and here we're near the top of the kernel
stack).  Or would the overhead be noticeable?

arm_syscall's cmpxchg emulation use pte_offset_map_lock, instead of
pte_offset_map and mm-wide page_table_lock; and strictly, it should now also
take mmap_sem before descending to pmd, to guard against another thread
munmapping, and the page table pulled out beneath this thread.

Updated two comments in fault-armv.c.  adjust_pte is interesting, since its
modification of a pte in one part of the mm depends on the lock held when
calling update_mmu_cache for a pte in some other part of that mm.  This can't
be done with a split page_table_lock (and we've already taken the lowest lock
in the hierarchy here): so we'll have to disable split on arm, unless
CONFIG_CPU_CACHE_VIPT to ensures adjust_pte never used.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 21:40:42 -07:00