Right now the kernel on x86-64 has a 100% lazy fpu behavior: after *every*
context switch a trap is taken for the first FPU use to restore the FPU
context lazily. This is of course great for applications that have very
sporadic or no FPU use (since then you avoid doing the expensive
save/restore all the time). However for very frequent FPU users... you
take an extra trap every context switch.
The patch below adds a simple heuristic to this code: After 5 consecutive
context switches of FPU use, the lazy behavior is disabled and the context
gets restored every context switch. If the app indeed uses the FPU, the
trap is avoided. (the chance of the 6th time slice using FPU after the
previous 5 having done so are quite high obviously).
After 256 switches, this is reset and lazy behavior is returned (until
there are 5 consecutive ones again). The reason for this is to give apps
that do longer bursts of FPU use still the lazy behavior back after some
time.
[akpm@osdl.org: place new task_struct field next to jit_keyring to save space]
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Andi Kleen <ak@muc.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
This patch enables ACPI based physical CPU hotplug support for x86_64.
Implements acpi_map_lsapic() and acpi_unmap_lsapic() to support physical cpu
hotplug.
Signed-off-by: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Andi Kleen <ak@muc.de>
Cc: "Brown, Len" <len.brown@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Now for a completely different but trivial approach.
I just boot tested it with 255 CPUS and everything worked.
Currently everything (except module data) we place in
the per cpu area we know about at compile time. So
instead of allocating a fixed size for the per_cpu area
allocate the number of bytes we need plus a fixed constant
for to be used for modules.
It isn't perfect but it is much less of a pain to
work with than what we are doing now.
AK: fixed warning
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Andi Kleen <ak@suse.de>
The implementation comes from Zach's [RFC, PATCH 10/24] i386 Vmi
descriptor changes:
Descriptor and trap table cleanups. Add cleanly written accessors for
IDT and GDT gates so the subarch may override them. Note that this
allows the hypervisor to transparently tweak the DPL of the descriptors
as well as the RPL of segments in those descriptors, with no unnecessary
kernel code modification. It also allows the hypervisor implementation
of the VMI to tweak the gates, allowing for custom exception frames or
extra layers of indirection above the guest fault / IRQ handlers.
Signed-off-by: Zachary Amsden <zach@vmware.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andi Kleen <ak@suse.de>
This patch moves the entry.S:error_entry to .kprobes.text section,
since code marked unsafe for kprobes jumps directly to entry.S::error_entry,
that must be marked unsafe as well.
This patch also moves all the ".previous.text" asm directives to ".previous"
for kprobes section.
AK: Following a similar i386 patch from Chuck Ebbert
AK: Also merged Jeremy's fix in.
+From: Jeremy Fitzhardinge <jeremy@goop.org>
KPROBE_ENTRY does a .section .kprobes.text, and expects its users to
do a .previous at the end of the function.
Unfortunately, if any code within the function switches sections, for
example .fixup, then the .previous ends up putting all subsequent code
into .fixup. Worse, any subsequent .fixup code gets intermingled with
the code its supposed to be fixing (which is also in .fixup). It's
surprising this didn't cause more havok.
The fix is to use .pushsection/.popsection, so this stuff nests
properly. A further cleanup would be to get rid of all
.section/.previous pairs, since they're inherently fragile.
+From: Chuck Ebbert <76306.1226@compuserve.com>
Because code marked unsafe for kprobes jumps directly to
entry.S::error_code, that must be marked unsafe as well.
The easiest way to do that is to move the page fault entry
point to just before error_code and let it inherit the same
section.
Also moved all the ".previous" asm directives for kprobes
sections to column 1 and removed ".text" from them.
Signed-off-by: Chuck Ebbert <76306.1226@compuserve.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Following x86-64 patches. Reuses code from them in fact.
Convert the standard backtracer to do all output using
callbacks. Use the x86-64 stack tracer implementation
that uses these callbacks to implement the stacktrace interface.
This allows to use the new dwarf2 unwinder for stacktrace
and get better backtraces.
Cc: mingo@elte.hu
Signed-off-by: Andi Kleen <ak@suse.de>
This unifies the standard backtracer and the new stacktrace
in memory backtracer. The standard one is converted to use callbacks
and then reimplement stacktrace using new callbacks.
The main advantage is that stacktrace can now use the new dwarf2 unwinder
and avoid false positives in many cases.
I kept it simple to make sure the standard backtracer stays reliable.
Cc: mingo@elte.hu
Signed-off-by: Andi Kleen <ak@suse.de>
Lockdep can call the dwarf2 unwinder early, and the dwarf2 code
uses safe_smp_processor_id which tries to access the local APIC page.
But that doesn't work before the APIC code has set up its fixmap.
Check for this case and always return boot cpu then.
Cc: jbeulich@novell.com
Cc: mingo@elte.hu
Signed-off-by: Andi Kleen <ak@suse.de>
- Remove unused all_contexts parameter
No caller used it
- Move skip argument into the structure (needed for
followon patches)
Cc: mingo@elte.hu
Signed-off-by: Andi Kleen <ak@suse.de>
Instead of hackish manual parsing
Requires earlier i386 patchkit, but also fixes i386 early_printk again.
I removed some obsolete really early parameters which didn't do anything useful.
Also made a few parameters that needed it early (mostly oops printing setup)
Also removed one panic check that wasn't visible without
early console anyways (the early console is now initialized after that
panic)
This cleans up a lot of code.
Signed-off-by: Andi Kleen <ak@suse.de>
This patch replaces the open-coded early commandline parsing
throughout the i386 boot code with the generic mechanism (already used
by ppc, powerpc, ia64 and s390). The code was inconsistent with
whether it deletes the option from the cmdline or not, meaning some of
these will get passed through the environment into init.
This transformation is mainly mechanical, but there are some notable
parts:
1) Grammar: s/linux never set's it up/linux never sets it up/
2) Remove hacked-in earlyprintk= option scanning. When someone
actually implements CONFIG_EARLY_PRINTK, then they can use
early_param().
[AK: actually it is implemented, but I'm adding the early_param it in the next
x86-64 patch]
3) Move declaration of generic_apic_probe() from setup.c into asm/apic.h
4) Various parameters now moved into their appropriate files (thanks Andi).
5) All parse functions which examine arg need to check for NULL,
except one where it has subtle humor value.
AK: readded acpi_sci handling which was completely dropped
AK: moved some more variables into acpi/boot.c
Cc: len.brown@intel.com
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andi Kleen <ak@suse.de>
Lock sections don't work the new dwarf2 unwinder
This generates slightly smaller code. It adds one more taken
jump to the fast path.
Cc: jbeulich@novell.com
Signed-off-by: Andi Kleen <ak@suse.de>
Lock sections don't work the new dwarf2 unwinder
This generates slightly smaller code. It adds one more taken
jump to the fast path.
Also move the trampolines into semaphore.S and add proper CFI
annotations.
Cc: jbeulich@novell.com
Signed-off-by: Andi Kleen <ak@suse.de>
Lock sections don't work the new dwarf2 unwinder
This generates slightly smaller code. It adds one more taken
jump to the fast path.
Cc: jbeulich@novell.com
Signed-off-by: Andi Kleen <ak@suse.de>
Move the tce_table_kva array, disabled bitmap and bus_to_phb array
into a new per bus 'struct calgary_bus_info'. Also slightly reorganize
build_tce_table and tce_table_setparms to avoid exporting bus_info to
tce.c.
Signed-off-by: Muli Ben-Yehuda <muli@il.ibm.com>
Signed-off-by: Jon Mason <jdmason@us.ibm.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Rearrange struct members loosely based on size for improved alignment
and to save a few bytes.
Signed-off-by: Muli Ben-Yehuda <muli@il.ibm.com>
Signed-off-by: Jon Mason <jdmason@us.ibm.com>
Signed-off-by: Andi Kleen <ak@suse.de>
The genapic field and the accessor macro weren't used anywhere.
Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Andi Kleen <ak@suse.de>
... instead of using a CONFIG option. The config option still controls
if the resulting executable actually has unwind information.
This is useful to prevent compilation errors when users select
CONFIG_STACK_UNWIND on old binutils and also allows to use
CFI in the future for non kernel debugging applications.
Cc: jbeulich@novell.com
Cc: sam@ravnborg.org
Signed-off-by: Andi Kleen <ak@suse.de>
They did not really belong into io_apic.c. Move them into a new file
and clean it up a bit.
Also remove outdated ATI quirk that was obsolete,
Signed-off-by: Andi Kleen <ak@suse.de>
PIC mode is an outdated way to drive the APICs that was used on
some early MP boards. It is not supported in the ACPI model.
It is unlikely to be ever configured by any x86-64 system
Remove it thus.
Signed-off-by: Andi Kleen <ak@suse.de>
- Convert CR* accesses to dedicated inline functions and rewrite
the rest as C inlines
- Don't do a double flush for global flushes (pointed out by Zach Amsden)
This was a bug workaround for old CPUs that don't do 64bit and is obsolete.
- Add a proper memory clobber to invlpg
- Remove an unused extern
Signed-off-by: Andi Kleen <ak@suse.de>
IO-APIC or local APIC can only be disabled at runtime anyways and
Kconfig has forced these options on for a long time now.
The Kconfigs are kept only now for the benefit of the shared acpi
boot.c code.
Signed-off-by: Andi Kleen <ak@suse.de>
- Move them to a pure assembly file. Previously they were in
a C file that only consisted of inline assembly. Doing it in pure
assembler is much nicer.
- Add a frame.i include with FRAME/ENDFRAME macros to easily
add frame pointers to assembly functions
- Add dwarf2 annotation to them so that the new dwarf2 unwinder
doesn't get stuck on them
- Random cleanups
Includes feedback from Jan Beulich and a UML build fix from Andrew
Morton.
Cc: jbeulich@novell.com
Cc: jdike@addtoit.com
Signed-off-by: Andi Kleen <ak@suse.de>
LOCK_PREFIX is replaced by nops on UP systems, so it has to be a special
macro. Previously this was only possible from C. Allow it for pure
assembly files too. Similar to earlier x86-64 patch.
Signed-off-by: Andi Kleen <ak@suse.de>
Previously it didn't align. Use the same one as the C compiler
in blended mode, which is good for K8 and Core2 and doesn't hurt
on P4.
Signed-off-by: Andi Kleen <ak@suse.de>
rwlocks are now out of line, so it near never triggers. Also it was
incompatible with the new dwarf2 unwinder because it had unannotiatable
push/pops.
Signed-off-by: Andi Kleen <ak@suse.de>
- Move the slow path fallbacks to their own assembly files
This makes them much easier to read and is needed for the next change.
- Add CFI annotations for unwinding (XXX need review)
- Remove constant case which can never happen with out of line spinlocks
- Use patchable LOCK prefixes
- Don't use lock sections anymore for inline code because they can't
be expressed by the unwinder (this adds one taken jump to the lock
fast path)
Cc: jbeulich@novell.com
Signed-off-by: Andi Kleen <ak@suse.de>
This ports the algorithm from x86-64 (with improvements) to i386.
Previously this only worked for frame pointer enabled kernels.
But spinlocks have a very simple stack frame that can be manually
analyzed. Do this.
Signed-off-by: Andi Kleen <ak@suse.de>
Hello,
Following my discussion with Andi. Here is a patch that introduces
two new TIF flags to simplify the context switch code in __switch_to().
The idea is to minimize the number of cache lines accessed in the common
case, i.e., when neither the debug registers nor the I/O bitmap are used.
This patch covers the x86-64 modifications. A patch for i386 follows.
Changelog:
- add TIF_DEBUG to track when debug registers are active
- add TIF_IO_BITMAP to track when I/O bitmap is used
- modify __switch_to() to use the new TIF flags
<signed-off-by>: eranian@hpl.hp.com
Signed-off-by: Andi Kleen <ak@suse.de>
For NUMA optimization and some other algorithms it is useful to have a fast
to get the current CPU and node numbers in user space.
x86-64 added a fast way to do this in a vsyscall. This adds a generic
syscall for other architectures to make it a generic portable facility.
I expect some of them will also implement it as a faster vsyscall.
The cache is an optimization for the x86-64 vsyscall optimization. Since
what the syscall returns is an approximation anyways and user space
often wants very fast results it can be cached for some time. The norma
methods to get this information in user space are relatively slow
The vsyscall is in a better position to manage the cache because it has direct
access to a fast time stamp (jiffies). For the generic syscall optimization
it doesn't help much, but enforce a valid argument to keep programs
portable
I only added an i386 syscall entry for now. Other architectures can follow
as needed.
AK: Also added some cleanups from Andrew Morton
Signed-off-by: Andi Kleen <ak@suse.de>
This patch adds a vgetcpu vsyscall, which depending on the CPU RDTSCP
capability uses either the RDTSCP or CPUID to obtain a CPU and node
numbers and pass them to the program.
AK: Lots of changes over Vojtech's original code:
Better prototype for vgetcpu()
It's better to pass the cpu / node numbers as separate arguments
to avoid mistakes when going from SMP to NUMA.
Also add a fast time stamp based cache using a user supplied
argument to speed things more up.
Use fast method from Chuck Ebbert to retrieve node/cpu from
GDT limit instead of CPUID
Made sure RDTSCP init is always executed after node is known.
Drop printk
Signed-off-by: Vojtech Pavlik <vojtech@suse.cz>
Signed-off-by: Andi Kleen <ak@suse.de>
This patch adds initalization of the RDTSCP auxilliary values to CPU numbers
to time.c. If RDTSCP is available, the MSRs are written with the respective
values. It can be later used to initalize per-cpu timekeeping variables.
AK: Some cleanups. Move externs into headers and fix CPU hotplug.
Signed-off-by: Vojtech Pavlik <vojtech@suse.cz>
Signed-off-by: Andi Kleen <ak@suse.de>
This patch adds macros for reading tsc via the RDTSCP instruction, as well
as writing the auxilliary MSR read by RDTSCP to msr.h
[AK: changed rdtscp definition for old binutils]
Signed-off-by: Vojtech Pavlik <vojtech@suse.cz>
Signed-off-by: Andi Kleen <ak@suse.de>
AK: This redoes the changes I temporarily reverted.
Intel now has support for Architectural Performance Monitoring Counters
( Refer to IA-32 Intel Architecture Software Developer's Manual
http://www.intel.com/design/pentium4/manuals/253669.htm ). This
feature is present starting from Intel Core Duo and Intel Core Solo processors.
What this means is, the performance monitoring counters and some performance
monitoring events are now defined in an architectural way (using cpuid).
And there will be no need to check for family/model etc for these architectural
events.
Below is the patch to use this performance counters in nmi watchdog driver.
Patch handles both i386 and x86-64 kernels.
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Andi Kleen <ak@suse.de>
When a unknown NMI happened the panic would claim a NMI watchdog timeout.
Also it would check the variable set by nmi_watchdog=panic and panic then.
Fix up the panic message to be generic
Unconditionally panic on unknown NMI when panic on unknown nmi is enabled.
Noticed by Jan Beulich
Cc: jbeulich@novell.com
Signed-off-by: Andi Kleen <ak@suse.de>
Making NMI suspend/resume work with SMP. We use CPU hotplug to offline
APs in SMP suspend/resume. Only BSP executes sysdev's .suspend/.resume
method. APs should follow CPU hotplug code path.
And:
+From: Don Zickus <dzickus@redhat.com>
Makes the start/stop paths of nmi watchdog more robust to handle the
suspend/resume cases more gracefully.
AK: I merged the two patches together
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Andi Kleen <ak@muc.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
To quote Alan Cox:
The default Linux behaviour on an NMI of either memory or unknown is to
continue operation. For many environments such as scientific computing
it is preferable that the box is taken out and the error dealt with than
an uncorrected parity/ECC error get propogated.
A small number of systems do generate NMI's for bizarre random reasons
such as power management so the default is unchanged. In other respects
the new proc/sys entry works like the existing panic controls already in
that directory.
This is separate to the edac support - EDAC allows supported chipsets to
handle ECC errors well, this change allows unsupported cases to at least
panic rather than cause problems further down the line.
Signed-off-by: Don Zickus <dzickus@redhat.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Adds a new /proc/sys/kernel/nmi call that will enable/disable the nmi
watchdog.
Signed-off-by: Don Zickus <dzickus@redhat.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Removes the un/set_nmi_callback and reserve/release_lapic_nmi functions as
they are no longer needed. The various subsystems are modified to register
with the die_notifier instead.
Also includes compile fixes by Andrew Morton.
Signed-off-by: Don Zickus <dzickus@redhat.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Dave Jones