VGA_MAP_MEM translates to ioremap() on some architectures. It makes sense
to do this to vga_vram_base, because we're going to access memory between
vga_vram_base and vga_vram_end.
But it doesn't really make sense to map starting at vga_vram_end, because
we aren't going to access memory starting there. On ia64, which always has
to be different, ioremapping vga_vram_end gives you something completely
incompatible with ioremapped vga_vram_start, so vga_vram_size ends up being
nonsense.
As a bonus, we often know the size up front, so we can use ioremap()
correctly, rather than giving it a zero size.
Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Cc: "Luck, Tony" <tony.luck@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
On partitioned PPC64 systems where a partition is given 1/10 of a
processor, we have seen mdelay() delaying for 10 times longer than it
should. The reason is that the generic mdelay(n) does n delays of 1
millisecond each. However, with 1/10 of a processor, we only get a
one-millisecond timeslice every 10ms. Thus each 1 millisecond delay
loop ends up taking 10ms elapsed time.
The solution is just to use the PPC64 udelay function, which uses the
timebase to ensure that the delay is based on elapsed time rather than
how much processing time the partition has been given. (Yes, the
generic mdelay uses the PPC64 udelay, but the problem is that the
start time gets reset every millisecond, and each time it gets reset
we lose another 9ms.)
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Acked-by: Andrew Morton <akpm@osdl.org>
Floating point exceptions should not be enabled by default,
as this setting impacts the performance on some CPUs, in
particular the Cell BE. Since the bits are inherited from
parent processes, the place to change the default is the
thread struct used for init.
glibc sets this up correctly per thread in its fesetenv
function, so user space should not be impacted by this
setting. None of the other common libc implementations
(uClibc, dietlibc, newlib, klibc) has support for fp
exceptions, so they are unlikely to be hit by this either.
There is a small risk that somebody wrote their own
application that manually sets the fpscr bits instead
of calling fesetenv, without changing the MSR bits as well.
Those programs will break with this change.
It probably makes sense to change glibc in the future
to be more clever about FE bits, so that when running
on a CPU where this is expensive, it disables exceptions
ASAP, while it keeps them enabled on CPUs where running
with exceptions on is cheaper than changing the state
often.
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Avoid duplication of the syscall table for the cell platform. Based on an
idea from David Woodhouse.
Signed-off-by: Andreas Schwab <schwab@suse.de>
Acked-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
On Tue, Jun 20, 2006 at 02:01:26PM +1000, Benjamin Herrenschmidt wrote:
> On Mon, 2006-06-19 at 13:08 -0700, Mark A. Greer wrote:
> > MPC10x-style interrupt controllers have a serial mode that allows
> > several interrupts to be clocked in through one INT signal.
> >
> > This patch adds the software support for that mode.
>
> You hard code the clock ratio... why not add a separate call to be
> called after mpic_init,
> something like mpic_set_serial_int(int mpic, int enable, int
> clock_ratio) ?
How's this?
--
MPC10x-style interrupt controllers have a serial mode that allows
several interrupts to be clocked in through one INT signal.
This patch adds the software support for that mode.
Signed-off-by: Mark A. Greer <mgreer@mvista.com>
--
arch/powerpc/sysdev/mpic.c | 20 ++++++++++++++++++++
include/asm-powerpc/mpic.h | 10 ++++++++++
2 files changed, 30 insertions(+)
--
Signed-off-by: Paul Mackerras <paulus@samba.org>
The SPU context save/restore code is currently built
for a 4k page size and we provide a _shipped version
of it since most people don't have the spu toolchain
that is needed to rebuild that code.
This patch hardcodes the data structures to a 64k
page alignment, which also guarantees 4k alignment
but unfortunately wastes 60k of memory per SPU
context that is created in the running system.
We will follow up on this with another patch to
reduce that overhead or maybe redo the context
save/restore logic to do this part entirely different,
but for now it should make experimental systems
work with either page size.
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
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>
This changes the hypervisor abstraction of setting cpu affinity to a
higher level to avoid platform dependent interrupt controller
routines. I replaced spu_priv1_ops:spu_int_route_set() with a
new routine spu_priv1_ops:spu_cpu_affinity_set().
As a by-product, this change eliminated what looked like an
existing bug in the set affinity code where spu_int_route_set()
mistakenly called int_stat_get().
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>
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>
This is a first version of support for the Cell BE "Reliability,
Availability and Serviceability" features.
It doesn't yet handle some of the RAS interrupts (the ones described in
iic_is/iic_irr), I'm still working on a proper way to expose these. They
are essentially a cascaded controller by themselves (sic !) though I may
just handle them locally to the iic driver. I need also to sync with
David Erb on the way he hooked in the performance monitor interrupt.
So that's all for 2.6.17 and I'll do more work on that with my rework of
the powerpc interrupt layer that I'm hacking on at the moment.
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Jeff Brown <Jeff.Brown@freescale.com>
Signed-off-by: Xianghua Xiao <x.xiao@freescale.com>
Signed-off-by: Jon Loeliger <jdl@freescale.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
* git://git.infradead.org/hdrcleanup-2.6: (63 commits)
[S390] __FD_foo definitions.
Switch to __s32 types in joystick.h instead of C99 types for consistency.
Add <sys/types.h> to headers included for userspace in <linux/input.h>
Move inclusion of <linux/compat.h> out of user scope in asm-x86_64/mtrr.h
Remove struct fddi_statistics from user view in <linux/if_fddi.h>
Move user-visible parts of drivers/s390/crypto/z90crypt.h to include/asm-s390
Revert include/media changes: Mauro says those ioctls are only used in-kernel(!)
Include <linux/types.h> and use __uXX types in <linux/cramfs_fs.h>
Use __uXX types in <linux/i2o_dev.h>, include <linux/ioctl.h> too
Remove private struct dx_hash_info from public view in <linux/ext3_fs.h>
Include <linux/types.h> and use __uXX types in <linux/affs_hardblocks.h>
Use __uXX types in <linux/divert.h> for struct divert_blk et al.
Use __u32 for elf_addr_t in <asm-powerpc/elf.h>, not u32. It's user-visible.
Remove PPP_FCS from user view in <linux/ppp_defs.h>, remove __P mess entirely
Use __uXX types in user-visible structures in <linux/nbd.h>
Don't use 'u32' in user-visible struct ip_conntrack_old_tuple.
Use __uXX types for S390 DASD volume label definitions which are user-visible
S390 BIODASDREADCMB ioctl should use __u64 not u64 type.
Remove unneeded inclusion of <linux/time.h> from <linux/ufs_fs.h>
Fix private integer types used in V4L2 ioctls.
...
Manually resolve conflict in include/linux/mtd/physmap.h
Reflect the fact that the Cell Broadband Engine supports 64k
pages by adding the bit to the CPU features.
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Currently the kernel blindly halts all the processors and calls the
ibm,suspend-me rtas call. If the firmware is not in the correct
state, we then re-start all the processors and return. It is much
smarter to first check the firmware state, and only if it is waiting,
call the ibm,suspend-me call.
Signed-off-by: Paul Mackerras <paulus@samba.org>
On non partitioned machines we currently set the HV bit in kernel space
only. It turns out we are supposed to maintain the HV bit in both user
and kernel space.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Allocate IOMMU tables local to the relevant node.
Signed-off-by: Anton Blanchard <anton@samba.org>
Acked-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Paul Mackerras <paulus@samba.org>
of_node_to_nid returns -1 if the associativity cannot be found. This
means pcibus_to_cpumask has to be careful not to pass a negative index into
node_to_cpumask.
Since pcibus_to_node could be used a lot, and of_node_to_nid is slow (it
walks a list doing strcmps), lets also cache the node in the
pci_controller struct.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Remove some stale POWER3/POWER4/970 on 32bit kernel support.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Forthcoming machines will extend the FPSCR to 64 bits. We already
had a 64-bit save area for the FPSCR, but we need to use a new form
of the mtfsf instruction. Fortunately this new form is decoded as
an ordinary mtfsf by existing 64-bit processors.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Instead of trying to make PPC64 MSI fit in a Intel-centric MSI layer, a
simple short-term solution is to hook the pci_{en/dis}able_msi() calls
and make a machdep call.
The rest of the MSI functions are superfluous for what is needed at this
time. Many of which can have machdep calls added as needed.
Ben and Michael Ellerman are looking into rewrite the MSI layer to be
more generic. However, in the meantime this works as a interim
solution.
Signed-off-by: Jake Moilanen <moilanen@austin.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Some POWER5+ machines can do 64k hardware pages for normal memory but
not for cache-inhibited pages. This patch lets us use 64k hardware
pages for most user processes on such machines (assuming the kernel
has been configured with CONFIG_PPC_64K_PAGES=y). User processes
start out using 64k pages and get switched to 4k pages if they use any
non-cacheable mappings.
With this, we use 64k pages for the vmalloc region and 4k pages for
the imalloc region. If anything creates a non-cacheable mapping in
the vmalloc region, the vmalloc region will get switched to 4k pages.
I don't know of any driver other than the DRM that would do this,
though, and these machines don't have AGP.
When a region gets switched from 64k pages to 4k pages, we do not have
to clear out all the 64k HPTEs from the hash table immediately. We
use the _PAGE_COMBO bit in the Linux PTE to indicate whether the page
was hashed in as a 64k page or a set of 4k pages. If hash_page is
trying to insert a 4k page for a Linux PTE and it sees that it has
already been inserted as a 64k page, it first invalidates the 64k HPTE
before inserting the 4k HPTE. The hash invalidation routines also use
the _PAGE_COMBO bit, to determine whether to look for a 64k HPTE or a
set of 4k HPTEs to remove. With those two changes, we can tolerate a
mix of 4k and 64k HPTEs in the hash table, and they will all get
removed when the address space is torn down.
Signed-off-by: Paul Mackerras <paulus@samba.org>
The pgdir field in the paca was a leftover from the dynamic VSIDs
patch, and is not used in the current kernel code. This removes it.
Signed-off-by: Paul Mackerras <paulus@samba.org>
This gives the ability to control whether alignment exceptions get
fixed up or reported to the process as a SIGBUS, using the existing
PR_SET_UNALIGN and PR_GET_UNALIGN prctls. We do not implement the
option of logging a message on alignment exceptions.
Signed-off-by: Paul Mackerras <paulus@samba.org>
This adds the PowerPC part of the code to allow processes to change
their endian mode via prctl.
This also extends the alignment exception handler to be able to fix up
alignment exceptions that occur in little-endian mode, both for
"PowerPC" little-endian and true little-endian.
We always enter signal handlers in big-endian mode -- the support for
little-endian mode does not amount to the creation of a little-endian
user/kernel ABI. If the signal handler returns, the endian mode is
restored to what it was when the signal was delivered.
We have two new kernel CPU feature bits, one for PPC little-endian and
one for true little-endian. Most of the classic 32-bit processors
support PPC little-endian, and this is reflected in the CPU feature
table. There are two corresponding feature bits reported to userland
in the AT_HWCAP aux vector entry.
This is based on an earlier patch by Anton Blanchard.
Signed-off-by: Paul Mackerras <paulus@samba.org>
POWER6 moves some of the MMCRA bits and also requires some bits to be
cleared each PMU interrupt.
Signed-off-by: Michael Neuling <mikey@neuling.org>
Acked-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Make sure dma_alloc_coherent allocates memory from the local node. This
is important on Cell where we avoid going through the slow cpu
interconnect.
Note: I could only test this patch on Cell, it should be verified on
some pseries machine by those that have the hardware.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Paul Mackerras <paulus@samba.org>
On 64bit powerpc we can find out what node a pci bus hangs off, so
implement the topology.h macros that export this information.
For 32bit this seems a little more difficult, but I don't know of 32bit
powerpc NUMA machines either, so let's leave it out for now.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Paul Mackerras <paulus@samba.org>
This patch attempts to handle RTAS "busy" return codes in a more simple
and consistent manner. Typical callers of RTAS shouldn't have to
manage wait times and delay calls.
This patch also changes the kernel to use msleep() rather than udelay()
when a runtime delay is necessary. This will avoid CPU soft lockups
for extended delay conditions.
Signed-off-by: John Rose <johnrose@austin.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Our MMU hash management code would not set the "C" bit (changed bit) in
the hardware PTE when updating a RO PTE into a RW PTE. That would cause
the hardware to possibly to a write back to the hash table to set it on
the first store access, which in addition to being a performance issue,
might also hit a bug when running with native hash management (non-HV)
as our code is specifically optimized for the case where no write back
happens.
Thus there is a very small therocial window were a hash PTE can become
corrupted if that HPTE has just been upgraded to read write, a store
access happens on it, and that races with another processor evicting
that same slot. Since eviction (caused by an almost full hash) is
extremely rare, the bug is very unlikely to happen fortunately.
This fixes by allowing the updating of the protection bits in the native
hash handling to also set (but not clear) the "C" bit, and, in order to
also improve performances in the general case, by always setting that
bit on newly inserted hash PTE so that writeback really never happens.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
This patch cleans up some locking & error handling in the ppc vdso and
moves the vdso base pointer from the thread struct to the mm context
where it more logically belongs. It brings the powerpc implementation
closer to Ingo's new x86 one and also adds an arch_vma_name() function
allowing to print [vsdo] in /proc/<pid>/maps if Ingo's x86 vdso patch is
also applied.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
I have tested PPC_PTRACE_GETREGS and PPC_PTRACE_SETREGS on umview.
I do not understand why historically these tags has been defined as
PPC_PTRACE_GETREGS and PPC_PTRACE_SETREGS instead of simply
PTRACE_[GS]ETREGS. The other "originality" is that the address must be
put into the "addr" field instead of the "data" field as stated in the
manual.
Signed-off-by: renzo davoli <renzo@cs.unibo.it>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Some driver wants to use CMSPAR, but it was missing on alpha and powerpc.
This adds it, with the same value as every other architecture uses.
(akpm: fixes the build of an upcoming gregkh USB patch)
Signed-off-by: Paul Mackerras <paulus@samba.org>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
There already exists a big endian safe bitops implementation in
lib/find_next_bit.c. The code in it is 90%+ common with the powerpc
specific version, so the powerpc version is redundant. This patch
makes the necessary changes to use the generic bitops in powerpc, and
removes the powerpc specific version.
Signed-off-by: Jon Mason <jdmason@us.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
As we now store enough information in the device_node.
Also the Flags field was not used either, do remove that.
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>
As we now store enough information in the device_node to allocate the
irq number in pcibios_final_fixup.
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>
We can now scan the list of device nodes instead. This also allows us
to remove the Device_list member of struct pci_dn.
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Add a function for generic parsing of dma-window properties (ie,
ibm,dma-window and ibm,my-dma-window) of pci and virtual device nodes.
This function will also be used by cell.
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Acked-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Paul Mackerras <paulus@samba.org>
This patch allows the compiler to catch any printf-like mismatches for
udbg_printf(). After some brute force building I've only found issues
with my own code and lparcfg.c It could break some developers, but
IMHO that would be goodness.
Signed-off-by: Jimi Xenidis <jimix@watson.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
We need to know the base address of the kdump kernel even when we're not a
kdump kernel, so add a #define for it. Move the logic that sets the kdump
kernelbase into kdump.h instead of page.h.
Rename kdump_setup() to setup_kdump_trampoline() to make it clearer what it's
doing, and add an empty definition for the !CRASH_DUMP case to avoid a
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>
We currently do mem= handling in three seperate places. And as benh pointed out
I wrote two of them. Now that we parse command line parameters earlier we can
clean this mess up.
Moving the parsing out of prom_init means the device tree might be allocated
above the memory limit. If that happens we'd have to move it. As it happens
we already have logic to do that for kdump, so just genericise it.
This also means we might have reserved regions above the memory limit, if we
do the bootmem allocator will blow up, so we have to modify
lmb_enforce_memory_limit() to truncate the reserves as well.
Tested on P5 LPAR, iSeries, F50, 44p. Tested moving device tree on P5 and
44p and F50.
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>
In reg.h we mostly have #define<space> but there are a few #define<tab>
around. Clean these up so we use space exclusively.
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
We have a case where __get_user and __put_user can validly be used
on kernel addresses in interrupt context - namely, the alignment
exception handler, as our get/put_unaligned just do a single access
and rely on the alignment exception handler to fix things up in the
rare cases where the cpu can't handle it in hardware. Thus we can
get alignment exceptions in the network stack at interrupt level.
The alignment exception handler does a __get_user to read the
instruction and blows up in might_sleep().
Since a __get_user on a kernel address won't actually ever sleep,
this makes the might_sleep conditional on the address being less
than PAGE_OFFSET.
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>
Change of_node_to_nid() to traverse the device tree, looking for a numa id.
Cell uses this to assign ids to SPUs, which are children of the CPU node.
Existing users of of_node_to_nid() are altered to use of_node_to_nid_single(),
which doesn't do the traversal.
Export an attach_sysdev_to_node() function, allowing system devices (eg.
SPUs) to link themselves into the numa topology in sysfs.
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>
It's been long overdue to kill the union tce_entry in the pSeries/iSeries
TCE code, especially since I asked the Summit guys to do it on the code
they copied from us.
Also, while I was at it, I cleaned up some whitespace.
Built and booted on pSeries, built on iSeries.
Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Paul Mackerras <paulus@samba.org>
This requires the compatible properties having vaules that are empty
strings instead of just being empty properties.
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>
As an added bonus, since every vio_dev now has a device_node
associated with it, hotplug now works.
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Add a cputable entry for the POWER6 processor.
The SIHV and SIPR bits in the mmcra have moved in POWER6, so disable
support for that until oprofile is fixed.
Also tell firmware that we know about POWER6.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
These aren't needed by glibc or klibc, and they're broken in some cases
anyway. The uClibc folks are apparently switching over to stop using
them too (now that we agreed that they should be dropped, at least).
Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Wire up *at syscalls.
This patch has been tested on ppc64 (using glibc's testsuite, both 32bit
and 64bit), and compile-tested for ppc32 (I have currently no ppc32 system
available, but I expect no problems).
Signed-off-by: Andreas Schwab <schwab@suse.de>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Some people report that we die on some Macs when we are expecting to
catch machine checks after poking at some random I/O address. I'd seen
it happen on my dual G4 with serial ports until we fixed those to use
OF, but now other users are reporting it with i8042.
This expands the use of check_legacy_ioport() to avoid that situation
even on 32-bit kernels.
Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
At present, ARCH=powerpc kernels can waste considerable space in
pagetables when making large hugepage mappings. Hugepage PTEs go in
PMD pages, but each PMD page maps 256M and so contains only 16
hugepage PTEs (128 bytes of data), but takes up a 1024 byte
allocation. With CONFIG_PPC_64K_PAGES enabled (64k base page size),
the situation is worse. Now hugepage PTEs are at the PTE page level
(also mapping 256M), so we store 16 hugepage PTEs in a 64k allocation.
The PowerPC MMU already means that any 256M region is either all
hugepage, or all normal pages. Thus, with some care, we can use a
different allocation for the hugepage PTE tables and only allocate the
128 bytes necessary.
Signed-off-by: Paul Mackerras <paulus@samba.org>
sys_splice() moves data to/from pipes with a file input/output. sys_vmsplice()
moves data to a pipe, with the input being a user address range instead.
This uses an approach suggested by Linus, where we can hold partial ranges
inside the pages[] map. Hopefully this will be useful for network
receive support as well.
Signed-off-by: Jens Axboe <axboe@suse.de>
machine_is() was always returning 0 when used in a module, because
we weren't exporting the machine definitions. This was why sound
wasn't working on powermacs when CONFIG_SND_POWERMAC=m. Original
fix from Ben Herrenschmidt, further fixed by me.
Signed-off-by: Paul Mackerras <paulus@samba.org>
The current PCI error recovery system keeps track of the number of PCI card
resets, and refuses to bring a card back up if this number is too large.
The goal of doing this was to avoid an infinite loop of resets if a card is
obviously dead. However, if the failures are rare, but the machine has a
high uptime, this mechanism might still be triggered; this is too harsh.
This patch will avoids this problem by decrementing the fail count after an
hour. Thus, as long as a pci card BSOD's less than 6 times an hour, it
will continue to be reset indefinitely. If it's failure rate is greater
than that, it will be taken off-line permanently.
This patch is larger than it might otherwise be because it changes
indentation by removing a pointless while-loop. The while loop is not
needed, as the handler is invoked once fo each event (by schedule_work());
the loop is leftover cruft from an earlier implementation.
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Cleanup patch which removes the io_page_mask. It fixes the reset on
some e1000 devices which is needed for clean kexec reboots. The legacy
devices which broke with this patch (parallel port and PC speaker) have
now been fixed in Linus' tree.
Signed-off-by: Anton Blanchard <anton@samba.org>
Acked-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Some devices don't support full 32-bit DMA address space, which we currently
assume. Add the required mask-passing to the IOMMU allocators.
Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Paul Mackerras <paulus@samba.org>
* git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc-merge:
powerpc: Use correct sequence for putting CPU into nap mode
[PATCH] spufs: fix context-switch decrementer code
[PATCH] powerpc32: Set cpu explicitly in kernel compiles
[PATCH] powerpc/pseries: bugfix: balance calls to pci_device_put
[PATCH] powerpc: Fix machine detection in prom_init.c
[PATCH] ppc32: Fix string comparing in platform_notify_map
[PATCH] powerpc: Avoid __initcall warnings
[PATCH] powerpc: Ensure runlatch is off in the idle loop
powerpc: Fix CHRP booting - needs a define_machine call
powerpc: iSeries has only 256 IRQs
We weren't using the recommended sequence for putting the CPU into
nap mode. When I changed the idle loop, for some reason 7447A cpus
started hanging when we put them into nap mode. Changing to the
recommended sequence fixes that.
The complexity here is that the recommended sequence is a loop that
keeps putting the cpu back into nap mode. Clearly we need some way
to break out of the loop when an interrupt (external interrupt,
decrementer, performance monitor) occurs. Here we use a bit in
the thread_info struct to indicate that we need this, and the exception
entry code notices this and arranges for the exception to return
to the value in the link register, thus breaking out of the loop.
We use a new `local_flags' field in the thread_info which we can
alter without needing to use an atomic update sequence.
The PPC970 has the same recommended sequence, so we do the same thing
there too.
This also fixes a bug in the kernel stack overflow handling code on
32-bit, since it was causing a value that we needed in a register to
get trashed.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Basically an in-kernel implementation of tee, which uses splice and the
pipe buffers as an intelligent way to pass data around by reference.
Where the user space tee consumes the input and produces a stdout and
file output, this syscall merely duplicates the data inside a pipe to
another pipe. No data is copied, the output just grabs a reference to the
input pipe data.
Signed-off-by: Jens Axboe <axboe@suse.de>
Current implementations define NODES_SHIFT in include/asm-xxx/numnodes.h for
each arch. Its definition is sometimes configurable. Indeed, ia64 defines 5
NODES_SHIFT values in the current git tree. But it looks a bit messy.
SGI-SN2(ia64) system requires 1024 nodes, and the number of nodes already has
been changeable by config. Suitable node's number may be changed in the
future even if it is other architecture. So, I wrote configurable node's
number.
This patch set defines just default value for each arch which needs multi
nodes except ia64. But, it is easy to change to configurable if necessary.
On ia64 the number of nodes can be already configured in generic ia64 and SN2
config. But, NODES_SHIFT is defined for DIG64 and HP'S machine too. So, I
changed it so that all platforms can be configured via CONFIG_NODES_SHIFT. It
would be simpler.
See also: http://marc.theaimsgroup.com/?l=linux-kernel&m=114358010523896&w=2
Signed-off-by: Yasunori Goto <y-goto@jp.fujitsu.com>
Cc: Hirokazu Takata <takata@linux-m32r.org>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Andi Kleen <ak@muc.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Jack Steiner <steiner@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
The iSeries Hypervisor only allows us to specify IRQ numbers up to 255 (it
has a u8 field to pass it in). This patch allows platforms to specify a
maximum to the virtual IRQ numbers we will use and has iSeries set that
to 255. If not set, the maximum is NR_IRQS - 1 (as before).
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
This patch removes unnecessary exports, marks functions as static when
possible, and simplifies some list-related code.
Signed-off-by: Nathan Fontenot <nfont@austin.ibm.com>
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
This extends the HCALL interface for InfiniBand usage. I've
made the patch against the linux-2.6 git tree and Segher's patch:
[PATCH] Change H_StudlyCaps to H_SHOUTING_CAPS
We moved this into the common powerpc code based on comments we
got after posting the first eHCA InfiniBand device driver patch.
Signed-off-by: Heiko j Schick <schickhj@de.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Also cleans up some nearby whitespace problems.
Signed-off-by: Segher Boessenkool <segher@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Previously we added NET_IP_ALIGN so an architecture can override the
padding done to align headers. The next step is to allow the skb
headroom to be overridden.
We currently always reserve 16 bytes to grow into, meaning all DMAs
start 16 bytes into a cacheline. On ppc64 we really want DMA writes to
start on a cacheline boundary, so we increase that headroom to one
cacheline.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This adds support for the sys_splice system call. Using a pipe as a
transport, it can connect to files or sockets (latter as output only).
From the splice.c comments:
"splice": joining two ropes together by interweaving their strands.
This is the "extended pipe" functionality, where a pipe is used as
an arbitrary in-memory buffer. Think of a pipe as a small kernel
buffer that you can use to transfer data from one end to the other.
The traditional unix read/write is extended with a "splice()" operation
that transfers data buffers to or from a pipe buffer.
Named by Larry McVoy, original implementation from Linus, extended by
Jens to support splicing to files and fixing the initial implementation
bugs.
Signed-off-by: Jens Axboe <axboe@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Remove oprofile spinlock backtrace code now we have proper calltrace
support. Also make MMCRA sihv and sipr bits a variable since they may
change in future cpus. Finally, MMCRA should be a 64bit quantity.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Add oprofile calltrace support to powerpc. Disable spinlock backtracing
now we can use calltrace info.
(Updated to work on both 32bit and 64bit by me).
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
for_each_cpu() actually iterates across all possible CPUs. We've had mistakes
in the past where people were using for_each_cpu() where they should have been
iterating across only online or present CPUs. This is inefficient and
possibly buggy.
We're renaming for_each_cpu() to for_each_possible_cpu() to avoid this in the
future.
This patch replaces for_each_cpu with for_each_possible_cpu.
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
This removes statically assigned platform numbers and reworks the
powerpc platform probe code to use a better mechanism. With this,
board support files can simply declare a new machine type with a
macro, and implement a probe() function that uses the flattened
device-tree to detect if they apply for a given machine.
We now have a machine_is() macro that replaces the comparisons of
_machine with the various PLATFORM_* constants. This commit also
changes various drivers to use the new macro instead of looking at
_machine.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
There are at least 14 different implementations of WARN() in the tree already.
The build fails all over the place.
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
We used to assume that a DMA mapping request with a NULL dev was for
ISA DMA. This assumption was broken at some point. Now we explicitly
pass the detected ISA PCI device in the floppy setup.
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>
These are some updates from both Ryan and Arnd for the hvc_console
driver:
The main point is to enable the inclusion of a console driver
for rtas, which is currrently needed for the cell platform.
Also shuffle around some data-type declarations and moves some
functions out of include/asm-ppc64/hvconsole.h and into a new
drivers/char/hvc_console.h file.
Signed-off-by: "Ryan S. Arnold" <rsa@us.ibm.com>
Signed-off-by: Arnd Bergmann <abergman@de.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
We need to export ppc64_firmware_features for modules. Before we do that
I think we should probably rename it to powerpc_firmware_features.
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Export validate_sp so we can use it in the oprofile calltrace code.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
- No one uses op_counter_config.valid, so remove it
- No need to ifdef around function protypes.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
32-bit CHRP machines are now supported only in arch/powerpc, as are
all 64-bit PowerPC processors. This means that we don't use
Open Firmware on any platform in arch/ppc any more.
This makes PReP support a single-platform option like every other
platform support option in arch/ppc now, thus CONFIG_PPC_MULTIPLATFORM
is gone from arch/ppc. CONFIG_PPC_PREP is the option that selects
PReP support and is generally what has replaced
CONFIG_PPC_MULTIPLATFORM within arch/ppc.
_machine is all but dead now, being #defined to 0.
Updated Makefiles, comments and Kconfig options generally to reflect
these changes.
Signed-off-by: Paul Mackerras <paulus@samba.org>
The kernel's implementation of notifier chains is unsafe. There is no
protection against entries being added to or removed from a chain while the
chain is in use. The issues were discussed in this thread:
http://marc.theaimsgroup.com/?l=linux-kernel&m=113018709002036&w=2
We noticed that notifier chains in the kernel fall into two basic usage
classes:
"Blocking" chains are always called from a process context
and the callout routines are allowed to sleep;
"Atomic" chains can be called from an atomic context and
the callout routines are not allowed to sleep.
We decided to codify this distinction and make it part of the API. Therefore
this set of patches introduces three new, parallel APIs: one for blocking
notifiers, one for atomic notifiers, and one for "raw" notifiers (which is
really just the old API under a new name). New kinds of data structures are
used for the heads of the chains, and new routines are defined for
registration, unregistration, and calling a chain. The three APIs are
explained in include/linux/notifier.h and their implementation is in
kernel/sys.c.
With atomic and blocking chains, the implementation guarantees that the chain
links will not be corrupted and that chain callers will not get messed up by
entries being added or removed. For raw chains the implementation provides no
guarantees at all; users of this API must provide their own protections. (The
idea was that situations may come up where the assumptions of the atomic and
blocking APIs are not appropriate, so it should be possible for users to
handle these things in their own way.)
There are some limitations, which should not be too hard to live with. For
atomic/blocking chains, registration and unregistration must always be done in
a process context since the chain is protected by a mutex/rwsem. Also, a
callout routine for a non-raw chain must not try to register or unregister
entries on its own chain. (This did happen in a couple of places and the code
had to be changed to avoid it.)
Since atomic chains may be called from within an NMI handler, they cannot use
spinlocks for synchronization. Instead we use RCU. The overhead falls almost
entirely in the unregister routine, which is okay since unregistration is much
less frequent that calling a chain.
Here is the list of chains that we adjusted and their classifications. None
of them use the raw API, so for the moment it is only a placeholder.
ATOMIC CHAINS
-------------
arch/i386/kernel/traps.c: i386die_chain
arch/ia64/kernel/traps.c: ia64die_chain
arch/powerpc/kernel/traps.c: powerpc_die_chain
arch/sparc64/kernel/traps.c: sparc64die_chain
arch/x86_64/kernel/traps.c: die_chain
drivers/char/ipmi/ipmi_si_intf.c: xaction_notifier_list
kernel/panic.c: panic_notifier_list
kernel/profile.c: task_free_notifier
net/bluetooth/hci_core.c: hci_notifier
net/ipv4/netfilter/ip_conntrack_core.c: ip_conntrack_chain
net/ipv4/netfilter/ip_conntrack_core.c: ip_conntrack_expect_chain
net/ipv6/addrconf.c: inet6addr_chain
net/netfilter/nf_conntrack_core.c: nf_conntrack_chain
net/netfilter/nf_conntrack_core.c: nf_conntrack_expect_chain
net/netlink/af_netlink.c: netlink_chain
BLOCKING CHAINS
---------------
arch/powerpc/platforms/pseries/reconfig.c: pSeries_reconfig_chain
arch/s390/kernel/process.c: idle_chain
arch/x86_64/kernel/process.c idle_notifier
drivers/base/memory.c: memory_chain
drivers/cpufreq/cpufreq.c cpufreq_policy_notifier_list
drivers/cpufreq/cpufreq.c cpufreq_transition_notifier_list
drivers/macintosh/adb.c: adb_client_list
drivers/macintosh/via-pmu.c sleep_notifier_list
drivers/macintosh/via-pmu68k.c sleep_notifier_list
drivers/macintosh/windfarm_core.c wf_client_list
drivers/usb/core/notify.c usb_notifier_list
drivers/video/fbmem.c fb_notifier_list
kernel/cpu.c cpu_chain
kernel/module.c module_notify_list
kernel/profile.c munmap_notifier
kernel/profile.c task_exit_notifier
kernel/sys.c reboot_notifier_list
net/core/dev.c netdev_chain
net/decnet/dn_dev.c: dnaddr_chain
net/ipv4/devinet.c: inetaddr_chain
It's possible that some of these classifications are wrong. If they are,
please let us know or submit a patch to fix them. Note that any chain that
gets called very frequently should be atomic, because the rwsem read-locking
used for blocking chains is very likely to incur cache misses on SMP systems.
(However, if the chain's callout routines may sleep then the chain cannot be
atomic.)
The patch set was written by Alan Stern and Chandra Seetharaman, incorporating
material written by Keith Owens and suggestions from Paul McKenney and Andrew
Morton.
[jes@sgi.com: restructure the notifier chain initialization macros]
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com>
Signed-off-by: Jes Sorensen <jes@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
- fix: initialize the robust list(s) to NULL in copy_process.
- doc update
- cleanup: rename _inuser to _inatomic
- __user cleanups and other small cleanups
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Ulrich Drepper <drepper@redhat.com>
Cc: Andi Kleen <ak@muc.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This patchset provides a new (written from scratch) implementation of robust
futexes, called "lightweight robust futexes". We believe this new
implementation is faster and simpler than the vma-based robust futex solutions
presented before, and we'd like this patchset to be adopted in the upstream
kernel. This is version 1 of the patchset.
Background
----------
What are robust futexes? To answer that, we first need to understand what
futexes are: normal futexes are special types of locks that in the
noncontended case can be acquired/released from userspace without having to
enter the kernel.
A futex is in essence a user-space address, e.g. a 32-bit lock variable
field. If userspace notices contention (the lock is already owned and someone
else wants to grab it too) then the lock is marked with a value that says
"there's a waiter pending", and the sys_futex(FUTEX_WAIT) syscall is used to
wait for the other guy to release it. The kernel creates a 'futex queue'
internally, so that it can later on match up the waiter with the waker -
without them having to know about each other. When the owner thread releases
the futex, it notices (via the variable value) that there were waiter(s)
pending, and does the sys_futex(FUTEX_WAKE) syscall to wake them up. Once all
waiters have taken and released the lock, the futex is again back to
'uncontended' state, and there's no in-kernel state associated with it. The
kernel completely forgets that there ever was a futex at that address. This
method makes futexes very lightweight and scalable.
"Robustness" is about dealing with crashes while holding a lock: if a process
exits prematurely while holding a pthread_mutex_t lock that is also shared
with some other process (e.g. yum segfaults while holding a pthread_mutex_t,
or yum is kill -9-ed), then waiters for that lock need to be notified that the
last owner of the lock exited in some irregular way.
To solve such types of problems, "robust mutex" userspace APIs were created:
pthread_mutex_lock() returns an error value if the owner exits prematurely -
and the new owner can decide whether the data protected by the lock can be
recovered safely.
There is a big conceptual problem with futex based mutexes though: it is the
kernel that destroys the owner task (e.g. due to a SEGFAULT), but the kernel
cannot help with the cleanup: if there is no 'futex queue' (and in most cases
there is none, futexes being fast lightweight locks) then the kernel has no
information to clean up after the held lock! Userspace has no chance to clean
up after the lock either - userspace is the one that crashes, so it has no
opportunity to clean up. Catch-22.
In practice, when e.g. yum is kill -9-ed (or segfaults), a system reboot is
needed to release that futex based lock. This is one of the leading
bugreports against yum.
To solve this problem, 'Robust Futex' patches were created and presented on
lkml: the one written by Todd Kneisel and David Singleton is the most advanced
at the moment. These patches all tried to extend the futex abstraction by
registering futex-based locks in the kernel - and thus give the kernel a
chance to clean up.
E.g. in David Singleton's robust-futex-6.patch, there are 3 new syscall
variants to sys_futex(): FUTEX_REGISTER, FUTEX_DEREGISTER and FUTEX_RECOVER.
The kernel attaches such robust futexes to vmas (via
vma->vm_file->f_mapping->robust_head), and at do_exit() time, all vmas are
searched to see whether they have a robust_head set.
Lots of work went into the vma-based robust-futex patch, and recently it has
improved significantly, but unfortunately it still has two fundamental
problems left:
- they have quite complex locking and race scenarios. The vma-based
patches had been pending for years, but they are still not completely
reliable.
- they have to scan _every_ vma at sys_exit() time, per thread!
The second disadvantage is a real killer: pthread_exit() takes around 1
microsecond on Linux, but with thousands (or tens of thousands) of vmas every
pthread_exit() takes a millisecond or more, also totally destroying the CPU's
L1 and L2 caches!
This is very much noticeable even for normal process sys_exit_group() calls:
the kernel has to do the vma scanning unconditionally! (this is because the
kernel has no knowledge about how many robust futexes there are to be cleaned
up, because a robust futex might have been registered in another task, and the
futex variable might have been simply mmap()-ed into this process's address
space).
This huge overhead forced the creation of CONFIG_FUTEX_ROBUST, but worse than
that: the overhead makes robust futexes impractical for any type of generic
Linux distribution.
So it became clear to us, something had to be done. Last week, when Thomas
Gleixner tried to fix up the vma-based robust futex patch in the -rt tree, he
found a handful of new races and we were talking about it and were analyzing
the situation. At that point a fundamentally different solution occured to
me. This patchset (written in the past couple of days) implements that new
solution. Be warned though - the patchset does things we normally dont do in
Linux, so some might find the approach disturbing. Parental advice
recommended ;-)
New approach to robust futexes
------------------------------
At the heart of this new approach there is a per-thread private list of robust
locks that userspace is holding (maintained by glibc) - which userspace list
is registered with the kernel via a new syscall [this registration happens at
most once per thread lifetime]. At do_exit() time, the kernel checks this
user-space list: are there any robust futex locks to be cleaned up?
In the common case, at do_exit() time, there is no list registered, so the
cost of robust futexes is just a simple current->robust_list != NULL
comparison. If the thread has registered a list, then normally the list is
empty. If the thread/process crashed or terminated in some incorrect way then
the list might be non-empty: in this case the kernel carefully walks the list
[not trusting it], and marks all locks that are owned by this thread with the
FUTEX_OWNER_DEAD bit, and wakes up one waiter (if any).
The list is guaranteed to be private and per-thread, so it's lockless. There
is one race possible though: since adding to and removing from the list is
done after the futex is acquired by glibc, there is a few instructions window
for the thread (or process) to die there, leaving the futex hung. To protect
against this possibility, userspace (glibc) also maintains a simple per-thread
'list_op_pending' field, to allow the kernel to clean up if the thread dies
after acquiring the lock, but just before it could have added itself to the
list. Glibc sets this list_op_pending field before it tries to acquire the
futex, and clears it after the list-add (or list-remove) has finished.
That's all that is needed - all the rest of robust-futex cleanup is done in
userspace [just like with the previous patches].
Ulrich Drepper has implemented the necessary glibc support for this new
mechanism, which fully enables robust mutexes. (Ulrich plans to commit these
changes to glibc-HEAD later today.)
Key differences of this userspace-list based approach, compared to the vma
based method:
- it's much, much faster: at thread exit time, there's no need to loop
over every vma (!), which the VM-based method has to do. Only a very
simple 'is the list empty' op is done.
- no VM changes are needed - 'struct address_space' is left alone.
- no registration of individual locks is needed: robust mutexes dont need
any extra per-lock syscalls. Robust mutexes thus become a very lightweight
primitive - so they dont force the application designer to do a hard choice
between performance and robustness - robust mutexes are just as fast.
- no per-lock kernel allocation happens.
- no resource limits are needed.
- no kernel-space recovery call (FUTEX_RECOVER) is needed.
- the implementation and the locking is "obvious", and there are no
interactions with the VM.
Performance
-----------
I have benchmarked the time needed for the kernel to process a list of 1
million (!) held locks, using the new method [on a 2GHz CPU]:
- with FUTEX_WAIT set [contended mutex]: 130 msecs
- without FUTEX_WAIT set [uncontended mutex]: 30 msecs
I have also measured an approach where glibc does the lock notification [which
it currently does for !pshared robust mutexes], and that took 256 msecs -
clearly slower, due to the 1 million FUTEX_WAKE syscalls userspace had to do.
(1 million held locks are unheard of - we expect at most a handful of locks to
be held at a time. Nevertheless it's nice to know that this approach scales
nicely.)
Implementation details
----------------------
The patch adds two new syscalls: one to register the userspace list, and one
to query the registered list pointer:
asmlinkage long
sys_set_robust_list(struct robust_list_head __user *head,
size_t len);
asmlinkage long
sys_get_robust_list(int pid, struct robust_list_head __user **head_ptr,
size_t __user *len_ptr);
List registration is very fast: the pointer is simply stored in
current->robust_list. [Note that in the future, if robust futexes become
widespread, we could extend sys_clone() to register a robust-list head for new
threads, without the need of another syscall.]
So there is virtually zero overhead for tasks not using robust futexes, and
even for robust futex users, there is only one extra syscall per thread
lifetime, and the cleanup operation, if it happens, is fast and
straightforward. The kernel doesnt have any internal distinction between
robust and normal futexes.
If a futex is found to be held at exit time, the kernel sets the highest bit
of the futex word:
#define FUTEX_OWNER_DIED 0x40000000
and wakes up the next futex waiter (if any). User-space does the rest of
the cleanup.
Otherwise, robust futexes are acquired by glibc by putting the TID into the
futex field atomically. Waiters set the FUTEX_WAITERS bit:
#define FUTEX_WAITERS 0x80000000
and the remaining bits are for the TID.
Testing, architecture support
-----------------------------
I've tested the new syscalls on x86 and x86_64, and have made sure the parsing
of the userspace list is robust [ ;-) ] even if the list is deliberately
corrupted.
i386 and x86_64 syscalls are wired up at the moment, and Ulrich has tested the
new glibc code (on x86_64 and i386), and it works for his robust-mutex
testcases.
All other architectures should build just fine too - but they wont have the
new syscalls yet.
Architectures need to implement the new futex_atomic_cmpxchg_inuser() inline
function before writing up the syscalls (that function returns -ENOSYS right
now).
This patch:
Add placeholder futex_atomic_cmpxchg_inuser() implementations to every
architecture that supports futexes. It returns -ENOSYS.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Arjan van de Ven <arjan@infradead.org>
Acked-by: Ulrich Drepper <drepper@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
PowerPC can use generic ones.
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
