fuse does not work on ARM due to cache incoherency issues - fuse wants
to use get_user_pages() to copy data from the current process into
kernel space. However, since this accesses userspace via the kernel
mapping, the kernel mapping can be out of date wrt data written to
userspace.
This can lead to unpredictable behaviour (in the case of fuse) or data
corruption for direct-IO.
This resolves debian bug #402876
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
iop33x gpio offset is correct in include/asm-arm/arch-iop33x/iop33x.h, but
include/asm-arm/hardware/iop3xx.h adds 4.
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Of the possible SSP frame formats (FRF bits in SSCR0), only SSCR0_PSP is defined. Other possible formats are Motorola SPI (0<<4), TI SSP (1<<4) and Microwire (2<<4). Attached patch adds a definition SSCR0_TISSP.
This mode is used for the sound codec attached to the PXA272 SSP1 of some HTC PDA phones.
Signed-off-by: Philipp Zabel <philipp.zabel@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
The SSCR0_SlotsPerFrm macro writes a 3-bit value to bits [2:0], while the correct location of FRDC in SSCR0 is at bits [26:24]. This patch adds the missing "<< 24".
Signed-off-by: Philipp Zabel <philipp.zabel@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
If PG_dcache_dirty is set for a page, we need to flush the source page
before performing any copypage operation using a different virtual address.
This fixes the copypage implementations for XScale, StrongARM and ARMv6.
This patch fixes segmentation faults seen in the dynamic linker under
the usage patterns in glibc 2.4/2.5.
Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Since iop13xx defines the PCI I/O spaces with physical resource addresses
the __io macro needs to perform the physical to virtual conversion. I
incorrectly assumed that this would be handled by ioremap, but drivers
(like e1000) directly dereference the address returned from __io.
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
The ARM EABI requires doubleword (8-byte) stack alignment at all public entry
points. The patch below makes the bFLT loader honour this.
It's always safe to start with a doubleword aligned stack so it doesn't seem
worth making this conditional on CONFIG_AEABI.
Paul
Signed-off-by: Paul Brook <paul@codesourcery.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
As reminded in http://lkml.org/lkml/2006/12/23/26, one should use
asm/hardware.h and asm/irq.h but absent-minded devs like me tends to use
asm/arch/hardware.h and/or asm/arch/irqs.h.
This patch aims at preventing such things.
In order to make it work, I had to modify asm-arm/irq.h too so that it can
be included from assembly files.
Also, as a side effect, I had to modify some headers who were using the
asm/arch/hardware.h or asm/arch/irqs.h.
Signed-off-by: Arnaud Patard <arnaud.patard@rtp-net.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Fix incorrect IRQ numbering in arch-ep93xx/irqs.h (source: Applied
Data Systems 2.6.17 kernel tree.)
Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
On ixp23xx, it was thought to be necessary to disable coherency to work
around certain silicon errata. This turns out not to be the case --
none of the documented errata workarounds require disabling coherency,
and disabling coherency does not work around any existing errata.
Furthermore, all ixp23xx models do support coherency, so we should just
unconditionally enable coherency for all ixp23xx.
Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
The phys_io/io_pg_offst machine record variables were being set
to bogus values, causing problems when enabling DEBUG_LL.
Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Add HWCAP_CRUNCH so that the dynamic linker knows whether it can
use Crunch-optimised libraries or not.
Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Move adjust_cr() into arch/arm/mm/mmu.c, and move irqflags.h to
a more appropriate place in the header file.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Change the include/asm-arm/arch-s3c2410/regs-serial.h
platform data to use the prorper type (upf_t) for the
uart_flags.
Fix all the other parts of arch/arm/mach-s3c2410 to
include <linux/serial_core.h> and all other uses of
the include file.
mach-rx3715.c:101:18: warning: incorrect type in initializer (different base types)
mach-rx3715.c:101:18: expected unsigned long [unsigned] uart_flags
mach-rx3715.c:101:18: got restricted unsigned int [usertype] [force] <noident>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Remove old (and non-shared) VA addresses from the mappings
in arch/arm/mach-s3c2410/map.h and anywhere they are being
mapped in arch/arm/mach-s3c2410
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Fix address-space conversion errors from passing addresses
generated from include/asm-arm/arch-s3c2410/map.h by adding
an __force argument to the `void __iomem *` for all the
virtual addresses.
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Fix address-space conversion errors from passing addresses
generated from include/asm-arm/arch-s3c2410/map.h by adding
an __force argument to the `void __iomem *` for all the
virtual addresses.
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Fix copyright notices in include/asm-arm/arch-s3c2410
to actually have `Copyright` in the line. This patch
deals with all the core files.
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Fix copyright notices in include/asm-arm/arch-s3c2410
to actually have `Copyright` in the line. This patch
deals with all the core files.
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Add:
sys_unshare
sys_set_robust_list
sys_get_robust_list
sys_splice
sys_arm_sync_file_range
sys_tee
sys_vmsplice
sys_move_pages
sys_getcpu
Special note about sys_arm_sync_file_range(), which is implemented as:
asmlinkage long sys_arm_sync_file_range(int fd, unsigned int flags,
loff_t offset, loff_t nbytes)
{
return sys_sync_file_range(fd, offset, nbytes, flags);
}
We can't export sys_sync_file_range() directly on ARM because the
argument list someone picked does not fit in the available registers.
Would be nice if... there was an arch maintainer review mechanism for
new syscalls before they hit the kernel.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
* 'for-linus' of master.kernel.org:/home/rmk/linux-2.6-arm:
[ARM] 4017/1: [Jornada7xx] - Updating Jornada720.c
[ARM] 3992/1: i.MX/MX1 CPU Frequency scaling support
[ARM] Provide a method to alter the control register
[ARM] 4016/1: prefetch macro is wrong wrt gcc's "delete-null-pointer-checks"
[ARM] Remove empty fixup function
[ARM] 4014/1: include drivers/hid/Kconfig
[ARM] 4013/1: clocksource driver for netx
[ARM] 4012/1: Clocksource for pxa
[ARM] Clean up ioremap code
[ARM] Unuse another Linux PTE bit
[ARM] Clean up KERNEL_RAM_ADDR
[ARM] Add sys_*at syscalls
[ARM] 4004/1: S3C24XX: UDC remove implict addition of VA to regs
[ARM] Formalise the ARMv6 processor name string
[ARM] Handle HWCAP_VFP in VFP support code
[ARM] 4011/1: AT91SAM9260: Fix compilation with NAND driver
[ARM] 4010/1: AT91SAM9260-EK board: Prepare for MACB Ethernet support
Support to change MX1 CPU frequency at runtime.
Tested on PiKRON's PiMX1 board and seems to be fully
stable up to 200 MHz end even as low as 8 MHz.
Signed-off-by: Pavel Pisa <pisa@cmp.felk.cvut.cz>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
i.MX needs to tweak the control register to support CPU frequency
scaling. Rather than have folk blindly try and change the control
register by writing to it and then wondering why it doesn't work,
provide a method (which is safe for UP only, and therefore only
available for UP) to achieve this.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
optimization
The gcc manual says:
|`-fdelete-null-pointer-checks'
| Use global dataflow analysis to identify and eliminate useless
| checks for null pointers. The compiler assumes that dereferencing
| a null pointer would have halted the program. If a pointer is
| checked after it has already been dereferenced, it cannot be null.
| Enabled at levels `-O2', `-O3', `-Os'.
Now the problem can be seen with this test case:
#include <linux/prefetch.h>
extern void bar(char *x);
void foo(char *x)
{
prefetch(x);
if (x)
bar(x);
}
Because the constraint to the inline asm used in the prefetch() macro is
a memory operand, gcc assumes that the asm code does dereference the
pointer and the delete-null-pointer-checks optimization kicks in.
Inspection of generated assembly for the above example shows that bar()
is indeed called unconditionally without any test on the value of x.
Of course in the prefetch case there is no real dereference and it
cannot be assumed that a null pointer would have been caught at that
point. This causes kernel oopses with constructs like
hlist_for_each_entry() where the list's 'next' content is prefetched
before the pointer is tested against NULL, and only when gcc feels like
applying this optimization which doesn't happen all the time with more
complex code.
It appears that the way to prevent delete-null-pointer-checks
optimization to occur in this case is to make prefetch() into a static
inline function instead of a macro. At least this is what is done on
x86_64 where a similar inline asm memory operand is used (I presume they
would have seen the same problem if it didn't work) and resulting code
for the above example confirms that.
An alternative would consist of replacing the memory operand by a
register operand containing the pointer, and use the addressing mode
explicitly in the asm template. But that would be less optimal than an
offsettable memory reference.
Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Virtually index, physically tagged cache architectures can get away
without cache flushing when forking. This patch adds a new cache
flushing function flush_cache_dup_mm(struct mm_struct *) which for the
moment I've implemented to do the same thing on all architectures
except on MIPS where it's a no-op.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Currently, to tell a task that it should go to the refrigerator, we set the
PF_FREEZE flag for it and send a fake signal to it. Unfortunately there
are two SMP-related problems with this approach. First, a task running on
another CPU may be updating its flags while the freezer attempts to set
PF_FREEZE for it and this may leave the task's flags in an inconsistent
state. Second, there is a potential race between freeze_process() and
refrigerator() in which freeze_process() running on one CPU is reading a
task's PF_FREEZE flag while refrigerator() running on another CPU has just
set PF_FROZEN for the same task and attempts to reset PF_FREEZE for it. If
the refrigerator wins the race, freeze_process() will state that PF_FREEZE
hasn't been set for the task and will set it unnecessarily, so the task
will go to the refrigerator once again after it's been thawed.
To solve first of these problems we need to stop using PF_FREEZE to tell
tasks that they should go to the refrigerator. Instead, we can introduce a
special TIF_*** flag and use it for this purpose, since it is allowed to
change the other tasks' TIF_*** flags and there are special calls for it.
To avoid the freeze_process()-refrigerator() race we can make
freeze_process() to always check the task's PF_FROZEN flag after it's read
its "freeze" flag. We should also make sure that refrigerator() will
always reset the task's "freeze" flag after it's set PF_FROZEN for it.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Pavel Machek <pavel@ucw.cz>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: David Howells <dhowells@redhat.com>
Cc: Andi Kleen <ak@muc.de>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
L_PTE_ASID is not really required to be stored in every PTE, since we
can identify it via the address passed to set_pte_at(). So, create
set_pte_ext() which takes the address of the PTE to set, the Linux
PTE value, and the additional CPU PTE bits which aren't encoded in
the Linux PTE value.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
* 'i2c-for-linus' of git://jdelvare.pck.nerim.net/jdelvare-2.6:
i2c: Fix OMAP clock prescaler to match the comment
i2c: Refactor a kfree in i2c-dev
i2c: Fix return value check in i2c-dev
i2c: Enable PEC on more i2c-i801 devices
i2c: Discard the i2c algo del_bus wrappers
i2c: New ARM Versatile/Realview bus driver
i2c: fix broken ds1337 initialization
i2c: i2c-i801 documentation update
i2c: Use the __ATTR macro where possible
i2c: Whitespace cleanups
i2c: Use put_user instead of copy_to_user where possible
i2c: New Atmel AT91 bus driver
i2c: Add support for nested i2c bus locking
i2c: Cleanups to the i2c-nforce2 bus driver
i2c: Add request/release_mem_region to i2c-ibm_iic bus driver
i2c: New Philips PNX bus driver
i2c: Delete the broken i2c-ite bus driver
i2c: Update the list of driver IDs
i2c: Fix documentation typos
New I2C bus driver for Philips ARM boards (Philips IP3204 I2C IP
block). This I2C controller can be found on (at least) PNX010x,
PNX52xx and PNX4008 Philips boards.
Signed-off-by: Vitaly Wool <vitalywool@gmail.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Stabilize PIO mode transfers against a range of word sizes and FIFO
thresholds and fixes word size setup/override issues.
1) 16 and 32 bit DMA/PIO transfers broken due to timing differences.
2) Potential for bad transfer counts due to transfer size assumptions.
3) Setup function broken is multiple ways.
4) Per transfer bit_per_word changes break DMA setup in pump_tranfers.
5) False positive timeout are not errors.
6) Changes in pxa2xx_spi_chip not effective in calls to setup.
7) Timeout scaling wrong for PXA255 NSSP.
8) Driver leaks memory while busy during unloading.
Known issues:
SPI_CS_HIGH and SPI_LSB_FIRST settings in struct spi_device are not handled.
Testing:
This patch has been test against the "random length, random bits/word,
random data (verified on loopback) and stepped baud rate by octaves
(3.6MHz to 115kHz)" test. It is robust in PIO mode, using any
combination of tx and rx thresholds, and also in DMA mode (which
internally computes the thresholds).
Much thanks to Ned Forrester for exhaustive reviews, fixes and testing.
The driver is substantially better for his efforts.
Signed-off-by: Stephen Street <stephen@streetfiresound.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This patch adds support for stn displays on the s3c2410 arm SoC.
The LCD type is choosen by a new field in the s3c2410fb_mach_info structure
and its value is the value of the PNRMODE bits. This worth to be noted as
a value of 0 means that you configure a 4 bit dual scan stn display.
Signed-off-by: Arnaud Patard <arnaud.patard@rtp-net.org>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Ben Dooks <ben-linux@fluff.org>
Acked-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
In order to sort out our struct termios and add proper speed control we need
to separate the kernel and user termios structures. Glibc is fine but the
other libraries rely on the kernel exported struct termios and we need to
extend this without breaking the ABI/API
To do so we add a struct ktermios which is the kernel view of a termios
structure and overlaps the struct termios with extra fields on the end for
now. (That limitation will go away in later patches). Some platforms (eg
alpha) planned ahead and thus use the same struct for both, others did not.
This just adds the structures but does not use them, it seems a sensible
splitting point for bisect if there are compile failures (not that I expect
them)
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Remove the implicit addition of a virtual address
to the UDC registers. This should have been done
by ioremap() in the driver, not by a static map.
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Don't set HWCAP_VFP in the processor support file; not only does it
depend on the processor features, but it also depends on the support
code being present. Therefore, only set it if the support code
detects that we have a VFP coprocessor attached.
Also, move the VFP handling of the coprocessor access register into
the VFP support code.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
* 'for-linus' of master.kernel.org:/home/rmk/linux-2.6-arm: (76 commits)
[ARM] 4002/1: S3C24XX: leave parent IRQs unmasked
[ARM] 4001/1: S3C24XX: shorten reboot time
[ARM] 3983/2: remove unused argument to __bug()
[ARM] 4000/1: Osiris: add third serial port in
[ARM] 3999/1: RX3715: suspend to RAM support
[ARM] 3998/1: VR1000: LED platform devices
[ARM] 3995/1: iop13xx: add iop13xx support
[ARM] 3968/1: iop13xx: add iop13xx_defconfig
[ARM] Update mach-types
[ARM] Allow gcc to optimise arm_add_memory a little more
[ARM] 3991/1: i.MX/MX1 high resolution time source
[ARM] 3990/1: i.MX/MX1 more precise PLL decode
[ARM] 3986/1: H1940: suspend to RAM support
[ARM] 3985/1: ixp4xx clocksource cleanup
[ARM] 3984/1: ixp4xx/nslu2: Fix disk LED numbering (take 2)
[ARM] 3994/1: ixp23xx: fix handling of pci master aborts
[ARM] 3981/1: sched_clock for PXA2xx
[ARM] 3980/1: extend the ARM Versatile sched_clock implementation from 32 to 63 bit
[ARM] 3979/1: extend the SA11x0 sched_clock implementation from 32 to 63 bit period
[ARM] 3978/1: macro to provide a 63-bit value from a 32-bit hardware counter
...
Merge:
Atmel AT91RM9200 and AT91SAM9260 changes
General ARM developments
Disconfiguous memory cleanups
64-bit/32-bit division and sched_clock extension patches
EP93xx support changes
IOP support changes
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Cut down the time between requesting a reboot
and actually getting the reboot to happen by
a quarter.
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
It appears that include/asm-arm/bug.h requires include/linux/stddef.h
for the definition of NULL. It seems that stddef.h was always included
indirectly in most cases, and that issue was properly fixed a while ago.
Then commit 5047f09b56 incorrectly reverted
change from commit ff10952a54 (bad dwmw2)
and the problem recently resurfaced.
Because the third argument to __bug() is never used anyway, RMK suggested
getting rid of it entirely instead of readding #include <linux/stddef.h>
which this patch does.
Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
The iop348 processor integrates an Xscale (XSC3 512KB L2 Cache) core with a
Serial Attached SCSI (SAS) controller, multi-ported DDR2 memory
controller, 3 Application Direct Memory Access (DMA) controllers, a 133Mhz
PCI-X interface, a x8 PCI-Express interface, and other peripherals to form
a system-on-a-chip RAID subsystem engine.
The iop342 processor replaces the SAS controller with a second Xscale core
for dual core embedded applications.
The iop341 processor is the single core version of iop342.
This patch supports the two Intel customer reference platforms iq81340mc
for external storage and iq81340sc for direct attach (HBA) development.
The developer's manual is available here:
ftp://download.intel.com/design/iio/docs/31503701.pdf
Changelog:
* removed virtual addresses from resource definitions
* cleaned up some unnecessary #include's
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Make the contents of the userspace asm/setup.h header consistent on all
architectures:
- export setup.h to userspace on all architectures
- export only COMMAND_LINE_SIZE to userspace
- frv: move COMMAND_LINE_SIZE from param.h
- i386: remove duplicate COMMAND_LINE_SIZE from param.h
- arm:
- export ATAGs to userspace
- change u8/u16/u32 to __u8/__u16/__u32
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Acked-by: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
dma_is_consistent() is ill-designed in that it does not have a struct
device pointer argument which makes proper support for systems that consist
of a mix of coherent and non-coherent DMA devices hard. Change
dma_is_consistent to take a struct device pointer as first argument and fix
the sole caller to pass it.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Cc: James Bottomley <James.Bottomley@steeleye.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
The last thing we agreed on was to remove the macros entirely for 2.6.19,
on all architectures. Unfortunately, I think nobody actually _did_ that,
so they are still there.
[akpm@osdl.org: x86_64 fix]
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Greg Schafer <gschafer@zip.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Enhanced resolution for time measurement functions.
Signed-off-by: Pavel Pisa <pisa@cmp.felk.cvut.cz>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Add support to suspend and resume, using the
H1940's bootloader
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: Arnaud Patard <arnaud.patard@rtp-net.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This patch fixes an error in the numbering of the disk LEDs on the
Linksys NSLU2. The error crept in because the physical location
of the LEDs has the Disk 2 LED *above* the Disk 1 LED.
Thanks to Gordon Farquharson for reporting this.
Signed-off-by: Rod Whitby <rod@whitby.id.au>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This is done in a completely lockless fashion. Bits 0 to 31 of the count
are provided by the hardware while bits 32 to 62 are stored in memory.
The top bit in memory is used to synchronize with the hardware count
half-period. When the top bit of both counters (hardware and in memory)
differ then the memory is updated with a new value, incrementing it when
the hardware counter wraps around. Because a word store in memory is
atomic then the incremented value will always be in synch with the top
bit indicating to any potential concurrent reader if the value in memory
is up to date or not wrt the needed increment. And any race in updating
the value in memory is harmless as the same value would be stored more
than once.
Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
On ARM all divisions have to be performed "manually". For 64-bit
divisions that may take more than a hundred cycles in many cases.
With 32-bit divisions gcc already use the recyprocal of constant
divisors to perform a multiplication, but not with 64-bit divisions.
Since the kernel is increasingly relying upon 64-bit divisions it is
worth optimizing at least those cases where the divisor is a constant.
This is what this patch does using plain C code that gets optimized away
at compile time.
For example, despite the amount of added C code, do_div(x, 10000) now
produces the following assembly code (where x is assigned to r0-r1):
adr r4, .L0
ldmia r4, {r4-r5}
umull r2, r3, r4, r0
mov r2, #0
umlal r3, r2, r5, r0
umlal r3, r2, r4, r1
mov r3, #0
umlal r2, r3, r5, r1
mov r0, r2, lsr #11
orr r0, r0, r3, lsl #21
mov r1, r3, lsr #11
...
.L0:
.word 948328779
.word 879609302
which is the fastest that can be done for any value of x in that case,
many times faster than the __do_div64 code (except for the small x value
space for which the result ends up being zero or a single bit).
The fact that this code is generated inline produces a tiny increase in
.text size, but not significant compared to the needed code around each
__do_div64 call site this code is replacing.
The algorithm used has been validated on a 16-bit scale for all possible
values, and then recodified for 64-bit values. Furthermore I've been
running it with the final BUG_ON() uncommented for over two months now
with no problem.
Note that this new code is compiled with gcc versions 4.0 or later.
Earlier gcc versions proved themselves too problematic and only the
original code is used with them.
Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Fix up arch-specific work items where possible to use the new work_struct and
delayed_work structs.
Three places that enqueue bits of their stack and then return have been marked
with #error as this is not permitted.
Signed-Off-By: David Howells <dhowells@redhat.com>
Russell King
Dan Williams
Philipp Zabel
Richard Purdie
Paul Brook
Arnaud Patard
Lennert Buytenhek
Ben Dooks
Linus Torvalds
Pavel Pisa
Nicolas Pitre
Ralf Baechle
Rafael J. Wysocki
Vitaly Wool
Stephen Street
Alan Cox
Adrian Bunk
Arnd Bergmann
Rod Whitby
David Howells