Commit graph

79739 commits

Author SHA1 Message Date
Thomas Gleixner
42e0a9aa5d x86: use u32 for some lapic functions
Use u32 so 32 and 64bit have the same interface.

Andrew Morton: xen, lguest build fixes

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-30 13:30:15 +01:00
Thomas Gleixner
3c6bb07ac1 x86: use u32 for safe_apic_wait_icr_idle()
Preperatory patch for merging apic headers.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-30 13:30:15 +01:00
Thomas Gleixner
37e650c7c8 x86: rename get_maxlvt to lapic_get_maxlvt
Use the same name for the 32 and 64 bit variant.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-30 13:30:14 +01:00
Thomas Gleixner
cff90dbfe4 x86: prepare unification of include/asm-x86/apic_32/64.h
White space and coding style clenaup.

Move the K8 local apic defines to apicdef.h, where they belong

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-30 13:30:14 +01:00
Thomas Gleixner
2d539553c9 x86: unify include/asm-x86/apicdef_32/64.h
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-30 13:30:14 +01:00
Thomas Gleixner
77e463d104 x86: merge arch/x86/kernel/ldt_32/64.c
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-30 13:30:14 +01:00
Thomas Gleixner
70f5088dd5 x86: prepare arch/x86/kernel/ldt_32/64.c for merging
White space and coding style cleanups.

Change unsigned to int. There is no win when we compare mincount against pc->size,
which is an int as well. Casting pc->size to unsigned just might hide real problems.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-30 13:30:13 +01:00
Thomas Gleixner
fc2d625c4f x86: introduce ldt_write accessor
Create a ldt write accessor like the 32 bit one.

Preparatory patch for merging ldt.c and anyway necessary for
64bit paravirt ops.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-30 13:30:13 +01:00
Thomas Gleixner
4edc8f5454 x86: clean up include/asm-x86/desc_64.h
White space and coding style clenaup.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-30 13:30:13 +01:00
Thomas Gleixner
78aa1f66f7 x86: clean up arch/x86/kernel/ldt_32/64.c
White space and coding style clenaup.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-30 13:30:13 +01:00
Thomas Gleixner
2f36fa13ce x86: clean up arch/x86/kernel/e820_64.c
White space and coding style cleanup.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-30 13:30:12 +01:00
Ingo Molnar
05fccb0e38 x86: code cleanups in arch/x86/kernel/pci-gart_64.c
code cleanups:

                                       errors   lines of code   errors/KLOC
 arch/x86/kernel/pci-gart_64.c            183             748         244.6
 arch/x86/kernel/pci-gart_64.c              0             790             0

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30 13:30:12 +01:00
Ingo Molnar
e8d591dc71 x86: lindent arch/i386/math-emu, cleanup
manually clean up some of the damage that lindent caused.
(this is a separate commit so that in the unlikely case of
a typo we can bisect it down to the manual edits.)

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30 13:30:12 +01:00
Ingo Molnar
3d0d14f983 x86: lindent arch/i386/math-emu
lindent these files:
                                       errors   lines of code   errors/KLOC
 arch/x86/math-emu/                      2236            9424         237.2
 arch/x86/math-emu/                       128            8706          14.7

no other changes. No code changed:

   text    data     bss     dec     hex filename
   5589802  612739 3833856 10036397         9924ad vmlinux.before
   5589802  612739 3833856 10036397         9924ad vmlinux.after

the intent of this patch is to ease the automated tracking of kernel
code quality - it's just much easier for us to maintain it if every file
in arch/x86 is supposed to be clean.

NOTE: it is a known problem of lindent that it causes some style damage
of its own, but it's a safe tool (well, except for the gcc array range
initializers extension), so we did the bulk of the changes via lindent,
and did the manual fixups in a followup patch.

the resulting math-emu code has been tested by Thomas Gleixner on a real
386 DX CPU as well, and it works fine.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30 13:30:11 +01:00
Ingo Molnar
a4ec1effce x86: mach-voyager, lindent
lindent the mach-voyager files to get rid of more than 300 style errors:

                                       errors   lines of code   errors/KLOC
 arch/x86/mach-voyager/   [old]           409            3729         109.6
 arch/x86/mach-voyager/   [new]            71            3678          19.3

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30 13:30:10 +01:00
Ingo Molnar
31183ba8fd x86: clean up arch/x86/kernel/aperture_64.c printk()s
clean up arch/x86/kernel/aperture_64.c printk()s.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30 13:30:10 +01:00
Ingo Molnar
c140df973c x86: clean up arch/x86/kernel/aperture_64.c
whitespace cleanup. No code changed:

   text    data     bss     dec     hex filename
   2080      76       4    2160     870 aperture_64.o.before
   2080      76       4    2160     870 aperture_64.o.after

                                       errors   lines of code   errors/KLOC
 arch/x86/kernel/aperture_64.c            114             299         381.2
 arch/x86/kernel/aperture_64.c              0             315             0

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30 13:30:09 +01:00
Thomas Gleixner
5bafb671e2 x86: clean up arch/x86/ia32/mmap32.c
White space and coding style clenaup.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-30 13:30:09 +01:00
Thomas Gleixner
6ec875666d x86: clean up arch/x86/ia32/syscall32.c
White space and coding style clenaup.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-30 13:30:08 +01:00
Thomas Gleixner
c202f298de x86: clean up arch/x86/ia32/sys_ia32.c
White space and coding style clenaup.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-30 13:30:08 +01:00
Thomas Gleixner
5de15d42e4 x86: clean up arch/x86/ia32/ptrace32.c
White space and coding style clenaup.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-30 13:30:08 +01:00
Thomas Gleixner
2da06b4e5d x86: clean up arch/x86/ia32/ipc32.c
White space and coding style cleanup.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-30 13:30:08 +01:00
Thomas Gleixner
99b9cdf758 x86: clean up arch/x86/ia32/ia32_signal.c
White space and coding style clenaup.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-30 13:30:07 +01:00
Thomas Gleixner
8edf8bee88 x86: clean up arch/x86/ia32/aout32.c
White space and coding style clenaup.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-30 13:30:07 +01:00
Thomas Gleixner
d94448b1fd x86: clean up arch/x86/ia32/fpu32.c
White space and coding style clenaup.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-30 13:30:07 +01:00
H. Peter Anvin
7b11fb5156 x86: unify asm/cpufeature.h
asm/cpufeature.h was already almost unified; this completes the job.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30 13:30:07 +01:00
H. Peter Anvin
e845c06bce x86: add <asm/asm.h>
Create <asm/asm.h>, with common definitions suitable for assembly
unification.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30 13:30:06 +01:00
Hiroshi Shimamoto
39d44a5147 x86: enable irq in default_idle on 64-bit
local_irq_enable() is missing after sched_clock_idle_wakeup_event().

Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-30 13:30:06 +01:00
Ingo Molnar
5ee613b675 x86: idle wakeup event in the HLT loop
do a proper idle-wakeup event on HLT as well - some CPUs stop the TSC
in HLT too, not just when going through the ACPI methods.

(the ACPI idle code already does this.)

[ update the 64-bit side too, as noticed by Jiri Slaby. ]

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30 13:30:06 +01:00
Guillaume Chazarain
53d517cdba x86: scale cyc_2_nsec according to CPU frequency
scale the sched_clock() cyc_2_nsec scaling factor according to
CPU frequency changes.

[ mingo@elte.hu: simplified it and fixed it for SMP. ]

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30 13:30:06 +01:00
Roland McGrath
83bd01024b x86: protect against sigaltstack wraparound
cf http://lkml.org/lkml/2007/10/3/41

To summarize: on Linux, SA_ONSTACK decides whether you are already on the
signal stack based on the value of the SP at the time of a signal.  If
you are not already inside the range, you are not "on the signal stack"
and so the new signal handler frame starts over at the base of the signal
stack.

sigaltstack (and sigstack before it) was invented in BSD.  There, the
SA_ONSTACK behavior has always been different.  It uses a kernel state
flag to decide, rather than the SP value.  When you first take an
SA_ONSTACK signal and switch to the alternate signal stack, it sets the
SS_ONSTACK flag in the thread's sigaltstack state in the kernel.
Thereafter you are "on the signal stack" and don't switch SP before
pushing a handler frame no matter what the SP value is.  Only when you
sigreturn from the original handler context do you clear the SS_ONSTACK
flag so that a new handler frame will start over at the base of the
alternate signal stack.

The undesireable effect of the Linux behavior is that an overflow of the
alternate signal stack can not only go undetected, but lead to a ring
buffer effect of clobbering the original handler frame at the base of the
signal stack for each successive signal that comes just after the
overflow.  This is what Shi Weihua's test case demonstrates.  Normally
this does not come up because of the signal mask, but the test case uses
SA_NODEFER for its SIGSEGV handler.

The other subtle part of the existing Linux semantics is that a simple
longjmp out of a signal handler serves to take you off the signal stack
in a safe and reliable fashion without having used sigreturn (nor having
just returned from the handler normally, which means the same).  After
the longjmp (or even informal stack switching not via any proper libc or
kernel interface), the alternate signal stack stands ready to be used
again.

A paranoid program would allocate a PROT_NONE red zone around its
alternate signal stack.  Then a small overflow would trigger a SIGSEGV in
handler setup, and be fatal (core dump) whether or not SIGSEGV is
blocked.  As with thread stack red zones, that cannot catch all overflows
(or underflows).  e.g., a local array as large as page size allocated in
a function called from a handler, but not actually touched before more
calls push more stack, could cause an overflow that silently pushes into
some unrelated allocated pages.

The BSD behavior does not do anything in particular about overflow.  But
it does at least avoid the wraparound or "ring buffer effect", so you'll
just get a straightforward all-out overflow down your address space past
the low end of the alternate signal stack.  I don't know what the BSD
behavior is for longjmp out of an SA_ONSTACK handler.

The POSIX wording relating to sigaltstack is pretty minimal.  I don't
think it speaks to this issue one way or another.  (The program that
overflows its stack is clearly in undefined behavior territory of one
sort or another anyhow.)

Given the longjmp issue and the potential for highly subtle complications
in existing programs relying on this in arcane ways deep in their code, I
am very dubious about changing the behavior to the BSD style persistent
flag.  I think Shi Weihua's patches have a similar effect by tracking the
SP used in the last handler setup.

I think it would be sensible for the signal handler setup code to detect
when it would itself be causing a stack overflow.  Maybe something like
the following patch (untested).  This issue exists in the same way on all
machines, so ideally they would all do a similar check.

When it's the handler function itself or its callees that cause the
overflow, rather than the signal handler frame setup alone crossing the
boundary, this still won't help.  But I don't see any way to distinguish
that from the valid longjmp case.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30 13:30:06 +01:00
Ingo Molnar
f9fc58910e x86: add DMI quirk for io-delay hangs on Compaq Presario V6000 laptops
add the DMI strings provided by Islam Amer <pharon@gmail.com>, for
the Compaq Presario V6000 (Quanta/30B7).

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30 13:30:05 +01:00
Ingo Molnar
d0049e71c6 x86: make io_delay=0xed the default
make io_delay=0xed the default. This frees up port 0x80 which is
a debug port on some machines and locks up certain laptops.

Testing only for now. Try the io_delay=0x80 boot option if this does not
work for you.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30 13:30:05 +01:00
Ingo Molnar
6e7c402590 x86: various changes and cleanups to in_p/out_p delay details
various changes to the in_p/out_p delay details:

- add the io_delay=none method
- make each method selectable from the kernel config
- simplify the delay code a bit by getting rid of an indirect function call
- add the /proc/sys/kernel/io_delay_type sysctl
- change 'io_delay=standard|alternate' to io_delay=0x80 and io_delay=0xed
- make the io delay config not depend on CONFIG_DEBUG_KERNEL

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: "David P. Reed" <dpreed@reed.com>
2008-01-30 13:30:05 +01:00
Rene Herman
b02aae9cf5 x86: provide a DMI based port 0x80 I/O delay override.
x86: provide a DMI based port 0x80 I/O delay override.

Certain (HP) laptops experience trouble from our port 0x80 I/O delay
writes. This patch provides for a DMI based switch to the "alternate
diagnostic port" 0xed (as used by some BIOSes as well) for these.

David P. Reed confirmed that port 0xed works for him and provides a
proper delay. The symptoms of _not_ working are a hanging machine,
with "hwclock" use being a direct trigger.

Earlier versions of this attempted to simply use udelay(2), with the
2 being a value tested to be a nicely conservative upper-bound with
help from many on the linux-kernel mailinglist but that approach has
two problems.

First, pre-loops_per_jiffy calibration (which is post PIT init while
some implementations of the PIT are actually one of the historically
problematic devices that need the delay) udelay() isn't particularly
well-defined. We could initialise loops_per_jiffy conservatively (and
based on CPU family so as to not unduly delay old machines) which
would sort of work, but...

Second, delaying isn't the only effect that a write to port 0x80 has.
It's also a PCI posting barrier which some devices may be explicitly
or implicitly relying on. Alan Cox did a survey and found evidence
that additionally some drivers may be racy on SMP without the bus
locking outb.

Switching to an inb() makes the timing too unpredictable and as such,
this DMI based switch should be the safest approach for now. Any more
invasive changes should get more rigid testing first. It's moreover
only very few machines with the problem and a DMI based hack seems
to fit that situation.

This also introduces a command-line parameter "io_delay" to override
the DMI based choice again:

	io_delay=<standard|alternate>

where "standard" means using the standard port 0x80 and "alternate"
port 0xed.

This retains the udelay method as a config (CONFIG_UDELAY_IO_DELAY) and
command-line ("io_delay=udelay") choice for testing purposes as well.

This does not change the io_delay() in the boot code which is using
the same port 0x80 I/O delay but those do not appear to be a problem
as David P. Reed reported the problem was already gone after using the
udelay version. He moreover reported that booting with "acpi=off" also
fixed things and seeing as how ACPI isn't touched until after this DMI
based I/O port switch I believe it's safe to leave the ones in the boot
code be.

The DMI strings from David's HP Pavilion dv9000z are in there already
and we need to get/verify the DMI info from other machines with the
problem, notably the HP Pavilion dv6000z.

This patch is partly based on earlier patches from Pavel Machek and
David P. Reed.

Signed-off-by: Rene Herman <rene.herman@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30 13:30:05 +01:00
Mike Galbraith
4c6b8b4d62 x86: fix: s2ram + P4 + tsc = annoyance
s2ram recently became useful here, except for the kernel's annoying
habit of disabling my P4's perfectly good TSC.

[  107.894470] CPU 1 is now offline
[  107.894474] SMP alternatives: switching to UP code
[  107.895832] CPU0 attaching sched-domain:
[  107.895836]  domain 0: span 1
[  107.895838]   groups: 1
[  107.896097] CPU1 is down
[    3.726156] Intel machine check architecture supported.
[    3.726165] Intel machine check reporting enabled on CPU#0.
[    3.726167] CPU0: Intel P4/Xeon Extended MCE MSRs (12) available
[    3.726170] CPU0: Thermal monitoring enabled
[    3.726175] Back to C!
[    3.726708] Force enabled HPET at resume
[    3.726775] Enabling non-boot CPUs ...
[    3.727049] CPU0 attaching NULL sched-domain.
[    3.727165] SMP alternatives: switching to SMP code
[    3.727858] Booting processor 1/1 eip 3000
[    3.727862] CPU 1 irqstacks, hard=b042f000 soft=b042d000
[    3.738173] Initializing CPU#1
[    3.798912] Calibrating delay using timer specific routine.. 5986.12 BogoMIPS (lpj=2993061)
[    3.798920] CPU: After generic identify, caps: bfebfbff 00000000 00000000 00000000 00004400 00000000 00000000 00000000
[    3.798931] CPU: Trace cache: 12K uops, L1 D cache: 8K
[    3.798934] CPU: L2 cache: 512K
[    3.798936] CPU: Physical Processor ID: 0
[    3.798938] CPU: After all inits, caps: bfebfbff 00000000 00000000 0000b080 00004400 00000000 00000000 00000000
[    3.798946] Intel machine check architecture supported.
[    3.798952] Intel machine check reporting enabled on CPU#1.
[    3.798955] CPU1: Intel P4/Xeon Extended MCE MSRs (12) available
[    3.798959] CPU1: Thermal monitoring enabled
[    3.799161] CPU1: Intel(R) Pentium(R) 4 CPU 3.00GHz stepping 09
[    3.799187] checking TSC synchronization [CPU#0 -> CPU#1]:
[    3.819181] Measured 63588552840 cycles TSC warp between CPUs, turning off TSC clock.
[    3.819184] Marking TSC unstable due to: check_tsc_sync_source failed.

If check_tsc_warp() is called after initial boot, and the TSC has in the
meantime been set (BIOS, user, silicon, elves) to a value lower than the
last stored/stale value, we blame the TSC.  Reset to pristine condition
after every test.

Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30 13:30:04 +01:00
Rafael J. Wysocki
5c9c9bec05 x86: hibernation: document __save_processor_state() on x86
Document the fact that __save_processor_state() has to save all CPU
registers referred to by the kernel in case a different kernel is
used to load and restore a hibernation image containing it.

Sigend-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30 13:30:04 +01:00
Sam Ravnborg
9484b1eb4d x86: fix make mrproper
Michael Opdenacker reported:

For backward compatibility with earlier (< 2.6.24) kernels,
arch/i386/boot/bzImage or arch/x86_64/boot/bzImage symbolic links to
arch/x86/boot/bzImage are created when you build an x86 kernel. The
arch/i386 or arch/x86_64 directories are then created for this only
purpose.

Issue: these generated directories and symbolic links are *not cleaned
up* when you run "make mrproper" (and thus "make distclean"). This
disturbs the production of patches, because the source tree is left with
generated files and directories.

Sam has an alternative fix:

The directory is killed during make clean as opposed to make mrproper.

Reported-by: Michael Opdenacker <michael-lists@free-electrons.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30 13:30:04 +01:00
Venki Pallipadi
6378ddb592 time: track accurate idle time with tick_sched.idle_sleeptime
Current idle time in kstat is based on jiffies and is coarse grained.
tick_sched.idle_sleeptime is making some attempt to keep track of idle time
in a fine grained manner.  But, it is not handling the time spent in
interrupts fully.

Make tick_sched.idle_sleeptime accurate with respect to time spent on
handling interrupts and also add tick_sched.idle_lastupdate, which keeps
track of last time when idle_sleeptime was updated.

This statistics will be crucial for cpufreq-ondemand governor, which can
shed some conservative gaurd band that is uses today while setting the
frequency.  The ondemand changes that uses the exact idle time is coming
soon.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30 13:30:04 +01:00
john stultz
bbe4d18ac2 NTP: correct inconsistent ntp interval/tick_length usage
I recently noticed on one of my boxes that when synched with an NTP
server, the drift value reported for the system was ~283ppm. While in
some cases, clock hardware can be that bad, it struck me as unusual as
the system was using the acpi_pm clocksource, which is one of the more
trustworthy and accurate clocksources on x86 hardware.

I brought up another system and let it sync to the same NTP server, and
I noticed a similar 280some ppm drift.

In looking at the code, I found that the acpi_pm's constant frequency
was being computed correctly at boot-up, however once the system was up,
even without the ntp daemon running, the clocksource's frequency was
being modified by the clocksource_adjust() function.

Digging deeper, I realized that in the code that keeps track of how much
the clocksource is skewing from the ntp desired time, we were using
different lengths to establish how long an time interval was.

The clocksource was being setup with the following interval:
	NTP_INTERVAL_LENGTH = NSEC_PER_SEC/NTP_INTERVAL_FREQ

While the ntp code was using the tick_length_base value:
	tick_length_base ~= (tick_usec * NSEC_PER_USEC * USER_HZ)
					/NTP_INTERVAL_FREQ

The subtle difference is:
	(tick_usec * NSEC_PER_USEC * USER_HZ) != NSEC_PER_SEC

This difference in calculation was causing the clocksource correction
code to apply a correction factor to the clocksource so the two
intervals were the same, however this results in the actual frequency of
the clocksource to be made incorrect. I believe this difference would
affect all clocksources, although to differing degrees depending on the
clocksource resolution.

The issue was introduced when my HZ free ntp patch landed in 2.6.21-rc1,
so my apologies for the mistake, and for not noticing it until now.

The following patch, corrects the clocksource's initialization code so
it uses the same interval length as the code in ntp.c. After applying
this patch, the drift value for the same system went from ~283ppm to
only 2.635ppm.

I believe this patch to be good, however it does affect all arches and
I've only tested on x86, so some caution is advised. I do think it would
be a likely candidate for a stable 2.6.24.x release.

Any thoughts or feedback would be appreciated.

Signed-off-by: John Stultz <johnstul@us.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30 13:30:03 +01:00
Balaji Rao
37a47db8d7 x86: assign IRQs to HPET timers, fix
Looks like IRQ 31 is assigned to timer 3, even without the patch!
I wonder who wrote the number 31. But the manual says that it is
zero by default.

I think we should check whether the timer has been allocated an IRQ before
proceeding to assign one to it.  Here is a patch that does this.

Signed-off-by: Balaji Rao <balajirrao@gmail.com>
Tested-by: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30 13:30:03 +01:00
Balaji Rao
e3f37a54f6 x86: assign IRQs to HPET timers
The userspace API for the HPET (see Documentation/hpet.txt) did not work. The
HPET_IE_ON ioctl was failing as there was no IRQ assigned to the timer
device. This patch fixes it by allocating IRQs to timer blocks in the HPET.

arch/x86/kernel/hpet.c |   13 +++++--------
drivers/char/hpet.c    |   45 ++++++++++++++++++++++++++++++++++++++-------
include/linux/hpet.h   |    2 +-
3 files changed, 44 insertions(+), 16 deletions(-)

Signed-off-by: Balaji Rao <balajirrao@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30 13:30:03 +01:00
Ingo Molnar
45fe4fe191 x86: make clockevents more robust
detect zero event-device multiplicators - they then cause
division-by-zero crashes if a clockevent has been initialized
incorrectly.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30 13:30:03 +01:00
Thomas Gleixner
1a0c009ac5 x86: unregister PIT clocksource when PIT is disabled
The following scenario might leave PIT as a disfunctional clock source:

    PIT is registered as clocksource
    PM_TIMER is registered as clocksource and enables highres/dyntick mode
    PIT is switched to oneshot mode
    -> now the readout of PIT is bogus, but the user might select PIT
    via the sysfs override, which would break the box as the time
    readout is unusable.

Unregister the PIT clocksource when the PIT clock event device is switched
into shutdown / oneshot mode.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-30 13:30:03 +01:00
Thomas Gleixner
4713e22ce8 clocksource: add unregister function to disable unusable clocksources
On x86 the PIT might become an unusable clocksource. Add an unregister
function to provide a possibilty to remove the PIT from the list of
available clock sources.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-30 13:30:02 +01:00
Thomas Gleixner
316da3b3fc x86: restrict PIT clocksource usage
PIT clocksource is registered unconditionally even when HPET is enabled
or when PIT is replaced by the local APIC timer. In both cases PIT can
not be used as it is stopped and the readout would be stale.

Prevent registering PIT in those cases.

patch depends on:

  x86: offer is_hpet_enabled() on !CONFIG_HPET_TIMER too

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-30 13:30:02 +01:00
Ingo Molnar
df619e6baf x86: offer is_hpet_enabled() on !CONFIG_HPET_TIMER too
offer is_hpet_enabled() on !CONFIG_HPET_TIMER too.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30 13:30:02 +01:00
Andi Kleen
1ada5cba6a clocksource: make clocksource watchdog cycle through online CPUs
This way it checks if the clocks are synchronized between CPUs too.
This might be able to detect slowly drifting TSCs which only
go wrong over longer time.

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30 13:30:02 +01:00
Parag Warudkar
1077f5a917 clocksource.c: use init_timer_deferrable for clocksource_watchdog
clocksource_watchdog can use a deferrable timer - reduces wakeups from
idle per second.

Signed-off-by: Parag Warudkar <parag.warudkar@gmail.com>
Cc: john stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30 13:30:01 +01:00
Geert Uytterhoeven
efd9ac8630 time: fold __get_realtime_clock_ts() into getnstimeofday()
- getnstimeofday() was just a wrapper around __get_realtime_clock_ts()
  - Replace calls to __get_realtime_clock_ts() by calls to getnstimeofday()
  - Fix bogus reference to get_realtime_clock_ts(), which never existed

Signed-off-by: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com>
Cc: john stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30 13:30:01 +01:00