s390/idle: remove arch_cpu_idle_time() and corresponding code

arch_cpu_idle_time() returns the idle time of any given cpu if it is in
idle, or zero if not. All if this is racy and partially incorrect. Time
stamps taken with store clock extended and store clock fast from different
cpus are compared, while the architecture states that this is nothing which
can be relied on (see Principles of Operation; Chapter 4, "Setting and
Inspecting the Clock").

A more fundamental problem is that the timestamp when a cpu is leaving idle
is taken early in the assembler part of the interrupt handler, and this
value is only transferred many cycles later to the cpu's per-cpu idle data
structure.

This per cpu data structure is read by arch_cpu_idle() to tell for which
period of time a remote cpu is idle: if only an idle_enter value is
present, the assumed idle time of the cpu is calculated by taking a local
timestamp and returning the difference of the local timestamp and the
idle_enter value. This is potentially incorrect, since the remote cpu may
have already left idle, but the taken timestamp may not have been
transferred to the per-cpu data structure. This in turn means that too much
idle time may be reported for a cpu, and a subsequent calculation of system
idle time may result in a smaller value.

Instead of coming up with even more complex code trying to fix this, just
remove this code, and only account idle time of a cpu, after idle state is
left.

Another minor bug is that it is assumed that timestamps are non-zero, which
is not necessarily the case for timestamps taken with store clock
fast. This however is just a very minor problem, since this can only happen
when the epoch increases.

Reviewed-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

s390: remove the last remnants of cputime_t

cputime_t was a core kernel type, removed by commits
ed5c8c854f2b..b672592f0221. As explained in commit b672592f0221
("sched/cputime: Remove generic asm headers"), the final cleanup is for
the arch to provide cputime_to_nsec[s](). Commit e53051e757d6
("s390/cputime: provide archicture specific cputime_to_nsecs") did that,
but just didn't remove the then-unused cputime_to_usecs() and associated
remnants.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Link: https://lore.kernel.org/r/20221006105635.115775-1-npiggin@gmail.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

s390: convert to generic entry

This patch converts s390 to use the generic entry infrastructure from
kernel/entry/*.

There are a few special things on s390:

- PIF_PER_TRAP is moved to TIF_PER_TRAP as the generic code doesn't
know about our PIF flags in exit_to_user_mode_loop().

- The old code had several ways to restart syscalls:

a) PIF_SYSCALL_RESTART, which was only set during execve to force a
restart after upgrading a process (usually qemu-kvm) to pgste page
table extensions.

b) PIF_SYSCALL, which is set by do_signal() to indicate that the
current syscall should be restarted. This is changed so that
do_signal() now also uses PIF_SYSCALL_RESTART. Continuing to use
PIF_SYSCALL doesn't work with the generic code, and changing it
to PIF_SYSCALL_RESTART makes PIF_SYSCALL and PIF_SYSCALL_RESTART
more unique.

- On s390 calling sys_sigreturn or sys_rt_sigreturn is implemented by
executing a svc instruction on the process stack which causes a fault.
While handling that fault the fault code sets PIF_SYSCALL to hand over
processing to the syscall code on exit to usermode.

The patch introduces PIF_SYSCALL_RET_SET, which is set if ptrace sets
a return value for a syscall. The s390x ptrace ABI uses r2 both for the
syscall number and return value, so ptrace cannot set the syscall number +
return value at the same time. The flag makes handling that a bit easier.
do_syscall() will just skip executing the syscall if PIF_SYSCALL_RET_SET
is set.

CONFIG_DEBUG_ASCE was removd in favour of the generic CONFIG_DEBUG_ENTRY.
CR1/7/13 will be checked both on kernel entry and exit to contain the
correct asces.

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if <5
lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

- when both scanners couldn't find any license traces, file was
considered to have no license information in it, and the top level
COPYING file license applied.

For non */uapi/* files that summary was:

SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 11139

and resulted in the first patch in this series.

If that file was a */uapi/* path one, it was "GPL-2.0 WITH
Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was:

SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 WITH Linux-syscall-note 930

and resulted in the second patch in this series.

- if a file had some form of licensing information in it, and was one
of the */uapi/* ones, it was denoted with the Linux-syscall-note if
any GPL family license was found in the file or had no licensing in
it (per prior point). Results summary:

SPDX license identifier # files
---------------------------------------------------|------
GPL-2.0 WITH Linux-syscall-note 270
GPL-2.0+ WITH Linux-syscall-note 169
((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21
((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17
LGPL-2.1+ WITH Linux-syscall-note 15
GPL-1.0+ WITH Linux-syscall-note 14
((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5
LGPL-2.0+ WITH Linux-syscall-note 4
LGPL-2.1 WITH Linux-syscall-note 3
((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3
((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1

and that resulted in the third patch in this series.

- when the two scanners agreed on the detected license(s), that became
the concluded license(s).

- when there was disagreement between the two scanners (one detected a
license but the other didn't, or they both detected different
licenses) a manual inspection of the file occurred.

- In most cases a manual inspection of the information in the file
resulted in a clear resolution of the license that should apply (and
which scanner probably needed to revisit its heuristics).

- When it was not immediately clear, the license identifier was
confirmed with lawyers working with the Linux Foundation.

- If there was any question as to the appropriate license identifier,
the file was flagged for further research and to be revisited later
in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights. The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
- a full scancode scan run, collecting the matched texts, detected
license ids and scores
- reviewing anything where there was a license detected (about 500+
files) to ensure that the applied SPDX license was correct
- reviewing anything where there was no detection but the patch license
was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
SPDX license was correct

This produced a worksheet with 20 files needing minor correction. This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg. Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected. This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.) Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

s390/cputime: provide archicture specific cputime_to_nsecs

The generic cputime_to_nsecs function first converts the cputime
to micro-seconds and then multiplies the result with 1000. This
looses some bits of accuracy, provide our own version of
cputime_to_nsecs that does not loose precision.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

s390/cputime: remove last traces of cputime_t

The cputime_t type is a thing of the past, replace the last occurences
of the type in the s390 code with a simple u64.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

s390, sched/cputime: Remove unused cputime definitions

Since the core doesn't deal with cputime_t anymore, most of these APIs
have been left unused. Lets remove these.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Link: http://lkml.kernel.org/r/1485832191-26889-34-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

s390, sched/cputime: Make arch_cpu_idle_time() to return nsecs

This way we don't need to deal with cputime_t details from the core code.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Link: http://lkml.kernel.org/r/1485832191-26889-32-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

s390: remove 31 bit support

Remove the 31 bit support in order to reduce maintenance cost and
effectively remove dead code. Since a couple of years there is no
distribution left that comes with a 31 bit kernel.

The 31 bit kernel also has been broken since more than a year before
anybody noticed. In addition I added a removal warning to the kernel
shown at ipl for 5 minutes: a960062e5826 ("s390: add 31 bit warning
message") which let everybody know about the plan to remove 31 bit
code. We didn't get any response.

Given that the last 31 bit only machine was introduced in 1999 let's
remove the code.
Anybody with 31 bit user space code can still use the compat mode.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

s390/cputime: fix 31-bit compile

git commit 8461b63ca01d125a245a0d0fb4821ea0656e5053
"s390: translate cputime magic constants to macros"
introduce a built error for 31-bit:

kernel/built-in.o: In function `posix_cpu_timer_set':
posix-cpu-timers.c:(.text+0x2a8cc): undefined reference to `__udivdi3'

The original code is actually broken for 31-bit and has been
corrected by the above commit by forcing the compiler to use
64-bit arithmetic through the CPUTIME_PER_USEC define.

To fix the compile error replace the 64-bit division with
a call to __div().

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

s390: translate cputime magic constants to macros

Make the code more self-explanatory by naming magic constants.

Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

s390/idle: consolidate idle functions and definitions

Move the C functions and definitions related to the idle state handling
to arch/s390/include/asm/idle.h and arch/s390/kernel/idle.c. The function
s390_get_idle_time is renamed to arch_cpu_idle_time and vtime_stop_cpu to
enabled_wait.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

s390/nohz: use a per-cpu flag for arch_needs_cpu

Move the nohz_delay bit from the s390_idle data structure to the
per-cpu flags. Clear the nohz delay flag in __cpu_disable and
remove the cpu hotplug notifier that used to do this.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

sched, time: Fix build error with 64 bit cputime_t on 32 bit systems

On 32 bit systems cmpxchg cannot handle 64 bit values, so
some additional magic is required to allow a 32 bit system
with CONFIG_VIRT_CPU_ACCOUNTING_GEN=y enabled to build.

Make sure the correct cmpxchg function is used when doing
an atomic swap of a cputime_t.

Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Rik van Riel <riel@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: umgwanakikbuti@gmail.com
Cc: fweisbec@gmail.com
Cc: srao@redhat.com
Cc: lwoodman@redhat.com
Cc: atheurer@redhat.com
Cc: oleg@redhat.com
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: linux390@de.ibm.com
Cc: linux-arch@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-s390@vger.kernel.org
Link: http://lkml.kernel.org/r/20140930155947.070cdb1f@annuminas.surriel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

s390: Replace __get_cpu_var uses

__get_cpu_var() is used for multiple purposes in the kernel source. One of
them is address calculation via the form &__get_cpu_var(x). This calculates
the address for the instance of the percpu variable of the current processor
based on an offset.

Other use cases are for storing and retrieving data from the current
processors percpu area. __get_cpu_var() can be used as an lvalue when
writing data or on the right side of an assignment.

__get_cpu_var() is defined as :

#define __get_cpu_var(var) (*this_cpu_ptr(&(var)))

__get_cpu_var() always only does an address determination. However, store
and retrieve operations could use a segment prefix (or global register on
other platforms) to avoid the address calculation.

this_cpu_write() and this_cpu_read() can directly take an offset into a
percpu area and use optimized assembly code to read and write per cpu
variables.

This patch converts __get_cpu_var into either an explicit address
calculation using this_cpu_ptr() or into a use of this_cpu operations that
use the offset. Thereby address calculations are avoided and less registers
are used when code is generated.

At the end of the patch set all uses of __get_cpu_var have been removed so
the macro is removed too.

The patch set includes passes over all arches as well. Once these operations
are used throughout then specialized macros can be defined in non -x86
arches as well in order to optimize per cpu access by f.e. using a global
register that may be set to the per cpu base.

Transformations done to __get_cpu_var()

1. Determine the address of the percpu instance of the current processor.

DEFINE_PER_CPU(int, y);
int *x = &__get_cpu_var(y);

Converts to

int *x = this_cpu_ptr(&y);

2. Same as #1 but this time an array structure is involved.

DEFINE_PER_CPU(int, y[20]);
int *x = __get_cpu_var(y);

Converts to

int *x = this_cpu_ptr(y);

3. Retrieve the content of the current processors instance of a per cpu
variable.

DEFINE_PER_CPU(int, y);
int x = __get_cpu_var(y)

Converts to

int x = __this_cpu_read(y);

4. Retrieve the content of a percpu struct

DEFINE_PER_CPU(struct mystruct, y);
struct mystruct x = __get_cpu_var(y);

Converts to

memcpy(&x, this_cpu_ptr(&y), sizeof(x));

5. Assignment to a per cpu variable

DEFINE_PER_CPU(int, y)
__get_cpu_var(y) = x;

Converts to

this_cpu_write(y, x);

6. Increment/Decrement etc of a per cpu variable

DEFINE_PER_CPU(int, y);
__get_cpu_var(y)++

Converts to

this_cpu_inc(y)

Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
CC: linux390@de.ibm.com
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

vtime: Describe overriden functions in dedicated arch headers

If the arch overrides some generic vtime APIs, let it describe
these on a dedicated and standalone header. This way it becomes
convenient to include it in vtime generic headers without irrelevant
stuff in such a low level header.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>

vtime: Consolidate a bit the ctx switch code

On ia64 and powerpc, vtime context switch only consists
in flushing system and user pending time, plus a few
arch housekeeping.

Consolidate that into a generic implementation. s390 is
a special case because pending user and system time accounting
there is hard to dissociate. So it's keeping its own implementation.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>

vtime: Consolidate system/idle context detection

Move the code that finds out to which context we account the
cputime into generic layer.

Archs that consider the whole time spent in the idle task as idle
time (ia64, powerpc) can rely on the generic vtime_account()
and implement vtime_account_system() and vtime_account_idle(),
letting the generic code to decide when to call which API.

Archs that have their own meaning of idle time, such as s390
that only considers the time spent in CPU low power mode as idle
time, can just override vtime_account().

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>

s390/vtimer: rework virtual timer interface

The current virtual timer interface is inherently per-cpu and hard to
use. The sole user of the interface is appldata which uses it to execute
a function after a specific amount of cputime has been used over all cpus.

Rework the virtual timer interface to hook into the cputime accounting.
This makes the interface independent from the CPU timer interrupts, and
makes the virtual timers global as opposed to per-cpu.
Overall the code is greatly simplified. The downside is that the accuracy
is not as good as the original implementation, but it is still good enough
for appldata.

Reviewed-by: Jan Glauber <jang@linux.vnet.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

s390/comments: unify copyright messages and remove file names

Remove the file name from the comment at top of many files. In most
cases the file name was wrong anyway, so it's rather pointless.

Also unify the IBM copyright statement. We did have a lot of sightly
different statements and wanted to change them one after another
whenever a file gets touched. However that never happened. Instead
people start to take the old/"wrong" statements to use as a template
for new files.
So unify all of them in one go.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>

s390/idle: reduce size of s390_idle_data structure

Avoid padding in the middle and the end of the data structure by
moving nohz_delay member to the beginning.
Saves eight byte per cpu.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

s390/headers: replace __s390x__ with CONFIG_64BIT where possible

Replace __s390x__ with CONFIG_64BIT in all places that are not exported
to userspace or guarded with #ifdef __KERNEL__.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

[S390] rework idle code

Whenever the cpu loads an enabled wait PSW it will appear as idle to the
underlying host system. The code in default_idle calls vtime_stop_cpu
which does the necessary voodoo to get the cpu time accounting right.
The udelay code just loads an enabled wait PSW. To correct this rework
the vtime_stop_cpu/vtime_start_cpu logic and move the difficult parts
to entry[64].S, vtime_stop_cpu can now be called from anywhere and
vtime_start_cpu is gone. The correction of the cpu time during wakeup
from an enabled wait PSW is done with a critical section in entry[64].S.
As vtime_start_cpu is gone, s390_idle_check can be removed as well.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

procfs: do not confuse jiffies with cputime64_t

Commit 2a95ea6c0d129b4 ("procfs: do not overflow get_{idle,iowait}_time
for nohz") did not take into account that one some architectures jiffies
and cputime use different units.

This causes get_idle_time() to return numbers in the wrong units, making
the idle time fields in /proc/stat wrong.

Instead of converting the usec value returned by
get_cpu_{idle,iowait}_time_us to units of jiffies, use the new function
usecs_to_cputime64 to convert it to the correct unit of cputime64_t.

Signed-off-by: Andreas Schwab <schwab@linux-m68k.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: "Artem S. Tashkinov" <t.artem@mailcity.com>
Cc: Dave Jones <davej@redhat.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

[S390] cputime: add sparse checking and cleanup

Make cputime_t and cputime64_t nocast to enable sparse checking to
detect incorrect use of cputime. Drop the cputime macros for simple
scalar operations. The conversion macros are still needed.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

[S390] nohz: optimize arch_needs_cpu()

arch_needs_cpu() gets always executed on the current cpu. Therefore
the cpu parameter can be ignored it is possible to use __get_cpu_var()
instead of per_cpu() to access the per_cpu variable, which will
generate better code.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

taskstats: use real microsecond granularity for CPU times

The taskstats interface uses microsecond granularity for the user and
system time values. The conversion from cputime to the taskstats values
uses the cputime_to_msecs primitive which effectively limits the
granularity to milliseconds. Add the cputime_to_usecs primitive for
architectures that have better, more precise CPU time values. Remove
cputime_to_msecs primitive because there are no more users left.

Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: Luck Tony <tony.luck@intel.com>
Cc: Shailabh Nagar <nagar1234@in.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Shailabh Nagar <nagar@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

[S390] idle time accounting vs. machine checks

A machine check can interrupt the i/o and external interrupt handler
anytime. If the machine check occurs while the interrupt handler is
waking up from idle vtime_start_cpu can get executed a second time
and the int_clock / async_enter_timer values in the lowcore get
clobbered. This can confuse the cpu time accounting.
To fix this problem two changes are needed. First the machine check
handler has to use its own copies of int_clock and async_enter_timer,
named mcck_clock and mcck_enter_timer. Second the nested execution
of vtime_start_cpu has to be prevented. This is done in s390_idle_check
by checking the wait bit in the program status word.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

nohz: Introduce arch_needs_cpu

Allow the architecture to request a normal jiffy tick when the system
goes idle and tick_nohz_stop_sched_tick is called . On s390 the hook is
used to prevent the system going fully idle if there has been an
interrupt other than a clock comparator interrupt since the last wakeup.

On s390 the HiperSockets response time for 1 connection ping-pong goes
down from 42 to 34 microseconds. The CPU cost decreases by 27%.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
LKML-Reference: <20090929122533.402715150@de.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

[S390] cputime: fix overflow on 31 bit systems

The cputime_to_msecs / cputime_to_clock_t and cputime64_to_clock_t
cause fixpoint divide exceptions if the cputime is too large.
On a machine that collected 49.7 days worth of idle time reading
from /proc/stat will generate oopses like this:

Kernel BUG at 001b0c92 [verbose debug info unavailable]
fixpoint divide exception: 0009 [#13] SMP
Modules linked in: ipv6
CPU: 1 Tainted: G D 2.6.27.10 #5
Process cat (pid: 21352, task: 1fb34138, ksp: 1d2a3d98)
Krnl PSW : 070c2000 801b0c92 (show_stat+0x2ca/0x68c)
R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:0 CC:2 PM:0
Krnl GPRS: 00000001 00001388 00000bb8 0015d2a1
00000000 00000000 000003e8 0001fd91
00000000 00000000 0000129d eecd2ff0
1cc533b9 0036f780 801b0bce 1d2a3cc0
Krnl Code: 801b0c86: f18890abf198 mvo 171(9,%r9),408(9,%r15)
801b0c8c: 98abf170 lm %r10,%r11,368(%r15)
801b0c90: 1da1 dr %r10,%r1
>801b0c92: 90abf170 stm %r10,%r11,368(%r15)
801b0c96: 98abf190 lm %r10,%r11,400(%r15)
801b0c9a: 1da1 dr %r10,%r1
801b0c9c: 90abf190 stm %r10,%r11,400(%r15)
801b0ca0: 18a3 lr %r10,%r3
Call Trace:
([<00000000001b09f4>] show_stat+0x2c/0x68c)
[<000000000018dcee>] seq_read+0xb2/0x364
[<00000000001a9980>] proc_reg_read+0x68/0x98
[<00000000001705ee>] vfs_read+0x6e/0xe8
[<0000000000170732>] sys_read+0x36/0x78
[<000000000010f750>] sysc_do_restart+0x12/0x16
[<0000000077f3ad6a>] 0x77f3ad6a
<4>---[ end trace 1436ea9559d3de9e ]---

Reported-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

cputime: Optimize jiffies_to_cputime(1)

For powerpc with CONFIG_VIRT_CPU_ACCOUNTING
jiffies_to_cputime(1) is not compile time constant and run time
calculations are quite expensive. To optimize we use
precomputed value. For all other architectures is is
preprocessor definition.

Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
LKML-Reference: <1248862529-6063-5-git-send-email-sgruszka@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

[S390] lockless idle time accounting

Replace the spinlock used in the idle time accounting with a sequence
counter mechanism analog to seqlock.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

[S390] merge cpu.h into cputime.h

All definition in cpu.h have to do with cputime accounting. Move
them to cputime.h and remove the header file.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

[S390] /proc/stat idle field for idle cpus

The cpu idle field in the output of /proc/stat is too small for cpus
that have been idle for more than a tick. Add the architecture hook
arch_idle_time that allows to add the not accounted idle time of a
sleeping cpu without waking the cpu.

The s390 implementation of arch_idle_time uses the already existing
s390_idle_data per_cpu variable to find the sleep time of a neighboring
idle cpu.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

[S390] Fix timeval regression on s390

commit aa5e97ce4bbc9d5daeec16b1d15bb3f6b7b4f4d4
[PATCH] improve precision of process accounting.

Introduced a timing regression:
-bash-3.2# time ls
real 0m0.006s
user 0m1.754s
sys 0m1.094s

The problem was introduced by an error in cputime_to_timeval.
Cputime is now 1/4096 microsecond, therefore, we have to divide
the remainder with 4096 to get the microseconds.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

[PATCH] improve precision of process accounting.

The unit of the cputime accouting values that are stored per process is
currently a microsecond. The CPU timer has a maximum granularity of
2**-12 microseconds. There is no benefit in storing the per process values
in the lesser precision and there is the disadvantage that the backend
has to do the rounding to microseconds. The better solution is to use
the maximum granularity of the CPU timer as cputime unit.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

[S390] move include/asm-s390 to arch/s390/include/asm

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>