s390: include linux/io.h instead of asm/io.h

Include linux/io.h instead of asm/io.h everywhere. linux/io.h includes
asm/io.h, so this shouldn't cause any problems. Instead this might help for
some randconfig build errors which were reported due to some undefined io
related functions.

Also move the changed include so it stays grouped together with other
includes from the same directory.

For ctcm_mpc.c also remove not needed comments (actually questions).

Acked-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>

s390/alternatives: provide identical sized orginal/alternative sequences

Explicitly provide identical sized original/alternative instruction
sequences. This way there is no need for the s390 specific alternatives
infrastructure to generate padding sequences.
The code which generates such sequences will be removed with a follow on
patch.

Acked-by: Vasily Gorbik <gor@linux.ibm.com>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Link: https://lore.kernel.org/r/20220511120532.2228616-2-hca@linux.ibm.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

s390/alternatives: use insn format for new instructions

Use insn format with instruction format specifier instead of plain
longs. This way it is also more obvious that code instead of data is
generated.

The generated code is identical.

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

s390/spinlock: remove incorrect kernel doc indicator

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

s390/spinlock: remove confusing comment in arch_spin_lock_wait

arch_spin_lock_wait does not take steal time into consideration.

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

s390/alternatives: make use of asm_inline

This is the s390 version of commit 40576e5e63ea ("x86: alternative.h:
use asm_inline for all alternative variants").

See commit eb111869301e ("compiler-types.h: add asm_inline
definition") for more details.

With this change the compiler will not generate many out-of-line
versions for the three instruction sized arch_spin_unlock() function
anymore. Due to this gcc seems to change a lot of other inline
decisions which results in a net 6k text size growth according to
bloat-o-meter (gcc 9.2 with defconfig).
But that's still better than having many out-of-line versions of
arch_spin_unlock().

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

s390/spinlock: fix indentation

checkpatch:
WARNING: Statements should start on a tabstop
#9499: FILE: arch/s390/lib/spinlock.c:231:
+ return;

sparse:
arch/s390/lib/spinlock.c:81 arch_load_niai4()
warn: inconsistent indenting

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

locking/atomics: COCCINELLE/treewide: Convert trivial ACCESS_ONCE() patterns to READ_ONCE()/WRITE_ONCE()

Please do not apply this to mainline directly, instead please re-run the
coccinelle script shown below and apply its output.

For several reasons, it is desirable to use {READ,WRITE}_ONCE() in
preference to ACCESS_ONCE(), and new code is expected to use one of the
former. So far, there's been no reason to change most existing uses of
ACCESS_ONCE(), as these aren't harmful, and changing them results in
churn.

However, for some features, the read/write distinction is critical to
correct operation. To distinguish these cases, separate read/write
accessors must be used. This patch migrates (most) remaining
ACCESS_ONCE() instances to {READ,WRITE}_ONCE(), using the following
coccinelle script:

----
// Convert trivial ACCESS_ONCE() uses to equivalent READ_ONCE() and
// WRITE_ONCE()

// $ make coccicheck COCCI=/home/mark/once.cocci SPFLAGS="--include-headers" MODE=patch

virtual patch

@ depends on patch @
expression E1, E2;
@@

- ACCESS_ONCE(E1) = E2
+ WRITE_ONCE(E1, E2)

@ depends on patch @
expression E;
@@

- ACCESS_ONCE(E)
+ READ_ONCE(E)
----

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: davem@davemloft.net
Cc: linux-arch@vger.kernel.org
Cc: mpe@ellerman.id.au
Cc: shuah@kernel.org
Cc: snitzer@redhat.com
Cc: thor.thayer@linux.intel.com
Cc: tj@kernel.org
Cc: viro@zeniv.linux.org.uk
Cc: will.deacon@arm.com
Link: http://lkml.kernel.org/r/1508792849-3115-19-git-send-email-paulmck@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

s390/spinlock: use cpu alternatives to enable niai instruction

Enable niai instruction in the spinlock code at run-time for machines
on which facility 49 is available (zEC12 and newer).

Signed-off-by: Vasily Gorbik <gor@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

s390/rwlock: introduce rwlock wait queueing

Like the common queued rwlock code the s390 implementation uses the
queued spinlock code on a spinlock_t embedded in the rwlock_t to achieve
the queueing. The encoding of the rwlock_t differs though, the counter
field in the rwlock_t is split into two parts. The upper two bytes hold
the write bit and the write wait counter, the lower two bytes hold the
read counter.

The arch_read_lock operation works exactly like the common qrwlock but
the enqueue operation for a writer follows a diffent logic. After the
failed inline try to get the rwlock in write, the writer first increases
the write wait counter, acquires the wait spin_lock for the queueing,
and then loops until there are no readers and the write bit is zero.
Without the write wait counter a CPU that just released the rwlock
could immediately reacquire the lock in the inline code, bypassing all
outstanding read and write waiters. For s390 this would cause massive
imbalances in favour of writers in case of a contended rwlock.

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

s390/spinlock: introduce spinlock wait queueing

The queued spinlock code for s390 follows the principles of the common
code qspinlock implementation but with a few notable differences.

The format of the spinlock_t locking word differs, s390 needs to store
the logical CPU number of the lock holder in the spinlock_t to be able
to use the diagnose 9c directed yield hypervisor call.

The inline code sequences for spin_lock and spin_unlock are nice and
short. The inline portion of a spin_lock now typically looks like this:

lhi %r0,0 # 0 indicates an empty lock
l %r1,0x3a0 # CPU number + 1 from lowcore
cs %r0,%r1,<some_lock> # lock operation
jnz call_wait # on failure call wait function
locked:
...
call_wait:
la %r2,<some_lock>
brasl %r14,arch_spin_lock_wait
j locked

A spin_unlock is as simple as before:

lhi %r0,0
sth %r0,2(%r2) # unlock operation

After a CPU has queued itself it may not enable interrupts again for the
arch_spin_lock_flags() variant. The arch_spin_lock_wait_flags wait function
is removed.

To improve performance the code implements opportunistic lock stealing.
If the wait function finds a spinlock_t that indicates that the lock is
free but there are queued waiters, the CPU may steal the lock up to three
times without queueing itself. The lock stealing update the steal counter
in the lock word to prevent more than 3 steals. The counter is reset at
the time the CPU next in the queue successfully takes the lock.

While the queued spinlocks improve performance in a system with dedicated
CPUs, in a virtualized environment with continuously overcommitted CPUs
the queued spinlocks can have a negative effect on performance. This
is due to the fact that a queued CPU that is preempted by the hypervisor
will block the queue at some point even without holding the lock. With
the classic spinlock it does not matter if a CPU is preempted that waits
for the lock. Therefore use the queued spinlock code only if the system
runs with dedicated CPUs and fall back to classic spinlocks when running
with shared CPUs.

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

s390/spinlock: use the cpu number +1 as spinlock value

The queued spinlock code will come out simpler if the encoding of
the CPU that holds the spinlock is (cpu+1) instead of (~cpu).

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

s390/spinlock: add niai spinlock hints

The z14 machine introduces new mode of the next-instruction-access-intent
NIAI instruction. With NIAI-8 it is possible to pin a cache-line on a
CPU for a small amount of time, NIAI-7 releases the cache-line again.
Finally NIAI-4 can be used to prevent the CPU to speculatively access
memory beyond the compare-and-swap instruction to get the lock.

Use these instruction in the spinlock code.

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

s390/spinlock: remove compare and delay instruction

The CAD instruction never worked quite as expected for the spinlock
code. It has been disabled by default with git commit 61b0b01686d48220,
if the "cad" kernel parameter is specified it is enabled for both user
space and the spinlock code. Leave the option to enable the instruction
for user space but remove it from the spinlock code.

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

s390/spinlock: use atomic primitives for spinlocks

Add a couple more __atomic_xxx function to atomic_ops.h and use them
to replace the compare-and-swap inlines in the spinlock code. This
changes the type of the lock value from unsigned int to int.

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

s390: replace ACCESS_ONCE with READ_ONCE

Remove the last places of ACCESS_ONCE in s390 code.

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

s390: Audit and remove any remaining unnecessary uses of module.h

Historically a lot of these existed because we did not have
a distinction between what was modular code and what was providing
support to modules via EXPORT_SYMBOL and friends. That changed
when we forked out support for the latter into the export.h file.

This means we should be able to reduce the usage of module.h
in code that is obj-y Makefile or bool Kconfig. The advantage
in doing so is that module.h itself sources about 15 other headers;
adding significantly to what we feed cpp, and it can obscure what
headers we are effectively using.

Since module.h was the source for init.h (for __init) and for
export.h (for EXPORT_SYMBOL) we consider each change instance
for the presence of either and replace as needed. An instance
where module_param was used without moduleparam.h was also fixed,
as well as implicit use of ptrace.h and string.h headers.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

locking/spinlocks, s390: Implement vcpu_is_preempted(cpu)

This implements the s390 version for vcpu_is_preempted(cpu),
by reworking the existing smp_vcpu_scheduled() function into
arch_vcpu_is_preempted().

We can then also get rid of the local cpu_is_preempted()
function by moving the CIF_ENABLED_WAIT test into
arch_vcpu_is_preempted().

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: David.Laight@ACULAB.COM
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: benh@kernel.crashing.org
Cc: boqun.feng@gmail.com
Cc: bsingharora@gmail.com
Cc: dave@stgolabs.net
Cc: jgross@suse.com
Cc: kernellwp@gmail.com
Cc: konrad.wilk@oracle.com
Cc: linuxppc-dev@lists.ozlabs.org
Cc: mpe@ellerman.id.au
Cc: paulmck@linux.vnet.ibm.com
Cc: paulus@samba.org
Cc: pbonzini@redhat.com
Cc: rkrcmar@redhat.com
Cc: virtualization@lists.linux-foundation.org
Cc: will.deacon@arm.com
Cc: xen-devel-request@lists.xenproject.org
Cc: xen-devel@lists.xenproject.org
Link: http://lkml.kernel.org/r/1478077718-37424-6-git-send-email-xinhui.pan@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

s390/spinlock: avoid yield to non existent cpu

arch_spin_lock_wait_flags() checks if a spinlock is not held before
trying a compare and swap instruction. If the lock is unlocked it
tries the compare and swap instruction, however if a different cpu
grabbed the lock in the meantime the instruction will fail as
expected.

Subsequently the arch_spin_lock_wait_flags() incorrectly tries to
figure out if the cpu that holds the lock is running. However it is
using the wrong cpu number for this (-1) and then will also yield the
current cpu to the wrong cpu.

Fix this by adding a missing continue statement.

Fixes: 470ada6b1a1d ("s390/spinlock: refactor arch_spin_lock_wait[_flags]")
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

s390/spinlock: do not yield to a CPU in udelay/mdelay

It does not make sense to try to relinquish the time slice with diag 0x9c
to a CPU in a state that does not allow to schedule the CPU. The scenario
where this can happen is a CPU waiting in udelay/mdelay while holding a
spin-lock.

Add a CIF bit to tag a CPU in enabled wait and use it to detect that the
yield of a CPU will not be successful and skip the diagnose call.

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

s390/spinlock: avoid diagnose loop

The spinlock implementation calls the diagnose 0x9c / 0x44 immediately
if the SIGP sense running reported the target CPU as not running.

The diagnose 0x9c is a hint to the hypervisor to schedule the target
CPU in preference to the source CPU that issued the diagnose. It can
happen that on return from the diagnose the target CPU has not been
scheduled yet, e.g. if the target logical CPU is on another physical
CPU and the hypervisor did not want to migrate the logical CPU.

Avoid the immediate repeat of the diagnose instruction, instead do
the retry loop before the next invocation of diagnose 0x9c.

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

s390/spinlock: use correct barriers

_raw_write_lock_wait first sets the high order bit to indicate a
pending writer and then waits for the reader to drop to zero.
smp_rmb by definition only orders reads against reads. Let's use
a full smp_mb instead. As right now smp_rmb is implemented
as full serialization, this needs no stable backport, but this
patch will be necessary if we reimplement smp_rmb.

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

s390/spinlock: add compare-and-delay to lock wait loops

Add the compare-and-delay instruction to the spin-lock and rw-lock
retry loops. A CPU executing the compare-and-delay instruction stops
until the lock value has changed. This is done to make the locking
code for contended locks to behave better in regard to the multi-
hreading facility. A thread of a core executing a compare-and-delay
will allow the other threads of a core to get a larger share of the
core resources.

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

s390/rwlock: use the interlocked-access facility 1 instructions

Make use of the load-and-add, load-and-or and load-and-and instructions
to atomically update the read-write lock without a compare-and-swap loop.

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

s390/rwlock: improve writer fairness

Set the write-lock bit in the out-of-line rwlock code to indicate that
a writer is waiting. Additional readers will no be able to get the lock
until at least one writer got the lock. Additional writers have to wait
for the first writer to release the lock again.

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

s390/rwlock: remove interrupt-enabling rwlock variant.

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

s390/rwlock: use directed yield for write-locked rwlocks

Add an owner field to the arch_rwlock_t to be able to pass the timeslice
of a virtual CPU with diagnose 0x9c to the lock owner in case the rwlock
is write-locked. The undirected yield in case the rwlock is acquired
writable but the lock is read-locked is removed.

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

s390/spinlock: refactor arch_spin_lock_wait[_flags]

Reorder the spinlock wait code to make it more readable.

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

s390/rwlock: add missing local_irq_restore calls

The out of line _raw_read_lock_wait_flags/_raw_write_lock_wait_flags
functions for the arch_read_lock_flags/arch_write_lock_flags calls
fail to re-enable the interrupts after another unsuccessful try to
get the lock with compare-and-swap. The following wait would be
done with interrupts disabled which is suboptimal.

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

s390/spinlock,rwlock: always to a load-and-test first

In case a lock is contended it is better to do a load-and-test first
before trying to get the lock with compare-and-swap. This helps to avoid
unnecessary cache invalidations of the cacheline for the lock if the
CPU has to wait for the lock. For an uncontended lock doing the
compare-and-swap directly is a bit better, if the CPU does not have the
cacheline in its cache yet the compare-and-swap will get it read-write
immediately while a load-and-test would get it read-only first.

Always to the load-and-test first to avoid the cacheline invalidations
for the contended case outweight the potential read-only to read-write
cacheline upgrade for the uncontended case.

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

s390/spinlock: fix system hang with spin_retry <= 0

On LPAR, when spin_retry is set to <= 0, arch_spin_lock_wait() and
arch_spin_lock_wait_flags() may end up in a while(1) loop w/o doing
any compare and swap operation. To fix this, use do/while instead of
for loop.

Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

s390/spinlock: optimize spinlock code sequence

Use lowcore constant to improve the code generated for spinlocks.

[ Martin Schwidefsky: patch breakdown and code beautification ]

Signed-off-by: Philipp Hachtmann <phacht@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

s390/spinlock: cleanup spinlock code

Improve the spinlock code in several aspects:
- Have _raw_compare_and_swap return true if the operation has been
successful instead of returning the old value.
- Remove the "volatile" from arch_spinlock_t and arch_rwlock_t
- Rename 'owner_cpu' to 'lock'
- Add helper functions arch_spin_trylock_once / arch_spin_tryrelease_once

[ Martin Schwidefsky: patch breakdown and code beautification ]

Signed-off-by: Philipp Hachtmann <phacht@linux.vnet.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] rework smp code

Define struct pcpu and merge some of the NR_CPUS arrays into it, including
__cpu_logical_map, current_set and smp_cpu_state. Split smp related
functions to those operating on physical cpus and the functions operating
on a logical cpu number. Make the functions for physical cpus use a
pointer to a struct pcpu. This hides the knowledge about cpu addresses in
smp.c, entry[64].S and swsusp_asm64.S, thus remove the sigp.h header.

The PSW restart mechanism is used to start secondary cpus, calling a
function on an online cpu, calling a function on the ipl cpu, and for
the nmi signal. Replace the different assembler functions with a
single function restart_int_handler. The new entry point calls a function
whose pointer is stored in the lowcore of the target cpu and it can wait
for the source cpu to stop. This covers all existing use cases.

Overall the code is now simpler and there are ~380 lines less code.

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

[S390] spinlock: check virtual cpu running status

This patch introduces a new function that checks the running status
of a cpu in a hypervisor. This status is not virtualized, so the check
is only correct if running in an LPAR. On acquiring a spinlock, if the
cpu holding the lock is scheduled by the hypervisor, we do a busy wait
on the lock. If it is not scheduled, we yield over to that cpu.

Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

[S390] Move __cpu_logical_map to smp.c

Finally move it to the place where it belongs to and make get rid of
it for !CONFIG_SMP.

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

locking: Convert raw_rwlock functions to arch_rwlock

Name space cleanup for rwlock functions. No functional change.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: linux-arch@vger.kernel.org

locking: Convert raw_rwlock to arch_rwlock

Not strictly necessary for -rt as -rt does not have non sleeping
rwlocks, but it's odd to not have a consistent naming convention.

No functional change.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: linux-arch@vger.kernel.org

locking: Convert __raw_spin* functions to arch_spin*

Name space cleanup. No functional change.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: linux-arch@vger.kernel.org

locking: Convert raw_spinlock to arch_spinlock

The raw_spin* namespace was taken by lockdep for the architecture
specific implementations. raw_spin_* would be the ideal name space for
the spinlocks which are not converted to sleeping locks in preempt-rt.

Linus suggested to convert the raw_ to arch_ locks and cleanup the
name space instead of using an artifical name like core_spin,
atomic_spin or whatever

No functional change.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: linux-arch@vger.kernel.org

[S390] implement interrupt-enabling rwlocks

arch backend for f5f7eac41db827a47b2163330eecd7bb55ae9f12
"Allow rwlocks to re-enable interrupts".

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

[S390] do local_irq_restore while spinning in spin_lock_irqsave.

In s390's spin_lock_irqsave, interrupts remain disabled while
spinning. In other architectures like x86 and powerpc, interrupts are
re-enabled while spinning if IRQ is not masked before spin_lock_irqsave
is called.

The following patch re-enables interrupts through local_irq_restore
while spinning for a lock acquisition.
This can improve system response.

[heiko.carstens@de.ibm.com: removed saving of pc]

Signed-off-by: Hisashi Hifumi <hifumi.hisashi@oss.ntt.co.jp>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

[S390] Remove owner_pc member from raw_spinlock_t.

Used to contain the address of the holder of the lock. But since the
spinlock code is not inlined anymore all locks contain the same address
anyway. And since in addtition nobody complained about that for ages
its obviously unused. So remove it.

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

[PATCH] Directed yield: direct yield of spinlocks for s390.

Use the new diagnose 0x9c in the spinlock implementation for s390. It
yields the remaining timeslice of the virtual cpu that tries to acquire a
lock to the virtual cpu that is the current holder of the lock.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] s390: Increase spinlock retry code performance

Currently the code tries up to spin_retry times to grab a lock using the cs
instruction. The cs instruction has exclusive access to a memory region
and therefore invalidates the appropiate cache line of all other cpus. If
there is contention on a lock this leads to cache line trashing. This can
be avoided if we first check wether a cs instruction is likely to succeed
before the instruction gets actually executed.

Signed-off-by: Christian Ehrhardt <ehrhardt@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] s390: spinlock fixes

Remove useless spin_retry_counter and fix compilation for UP kernels.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] s390: cleanup Kconfig

Sanitize some s390 Kconfig options. We have ARCH_S390, ARCH_S390X,
ARCH_S390_31, 64BIT, S390_SUPPORT and COMPAT. Replace these 6 options by
S390, 64BIT and COMPAT.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] spinlock consolidation

This patch (written by me and also containing many suggestions of Arjan van
de Ven) does a major cleanup of the spinlock code. It does the following
things:

- consolidates and enhances the spinlock/rwlock debugging code

- simplifies the asm/spinlock.h files

- encapsulates the raw spinlock type and moves generic spinlock
features (such as ->break_lock) into the generic code.

- cleans up the spinlock code hierarchy to get rid of the spaghetti.

Most notably there's now only a single variant of the debugging code,
located in lib/spinlock_debug.c. (previously we had one SMP debugging
variant per architecture, plus a separate generic one for UP builds)

Also, i've enhanced the rwlock debugging facility, it will now track
write-owners. There is new spinlock-owner/CPU-tracking on SMP builds too.
All locks have lockup detection now, which will work for both soft and hard
spin/rwlock lockups.

The arch-level include files now only contain the minimally necessary
subset of the spinlock code - all the rest that can be generalized now
lives in the generic headers:

include/asm-i386/spinlock_types.h | 16
include/asm-x86_64/spinlock_types.h | 16

I have also split up the various spinlock variants into separate files,
making it easier to see which does what. The new layout is:

SMP | UP
----------------------------|-----------------------------------
asm/spinlock_types_smp.h | linux/spinlock_types_up.h
linux/spinlock_types.h | linux/spinlock_types.h
asm/spinlock_smp.h | linux/spinlock_up.h
linux/spinlock_api_smp.h | linux/spinlock_api_up.h
linux/spinlock.h | linux/spinlock.h

/*
* here's the role of the various spinlock/rwlock related include files:
*
* on SMP builds:
*
* asm/spinlock_types.h: contains the raw_spinlock_t/raw_rwlock_t and the
* initializers
*
* linux/spinlock_types.h:
* defines the generic type and initializers
*
* asm/spinlock.h: contains the __raw_spin_*()/etc. lowlevel
* implementations, mostly inline assembly code
*
* (also included on UP-debug builds:)
*
* linux/spinlock_api_smp.h:
* contains the prototypes for the _spin_*() APIs.
*
* linux/spinlock.h: builds the final spin_*() APIs.
*
* on UP builds:
*
* linux/spinlock_type_up.h:
* contains the generic, simplified UP spinlock type.
* (which is an empty structure on non-debug builds)
*
* linux/spinlock_types.h:
* defines the generic type and initializers
*
* linux/spinlock_up.h:
* contains the __raw_spin_*()/etc. version of UP
* builds. (which are NOPs on non-debug, non-preempt
* builds)
*
* (included on UP-non-debug builds:)
*
* linux/spinlock_api_up.h:
* builds the _spin_*() APIs.
*
* linux/spinlock.h: builds the final spin_*() APIs.
*/

All SMP and UP architectures are converted by this patch.

arm, i386, ia64, ppc, ppc64, s390/s390x, x64 was build-tested via
crosscompilers. m32r, mips, sh, sparc, have not been tested yet, but should
be mostly fine.

From: Grant Grundler <grundler@parisc-linux.org>

Booted and lightly tested on a500-44 (64-bit, SMP kernel, dual CPU).
Builds 32-bit SMP kernel (not booted or tested). I did not try to build
non-SMP kernels. That should be trivial to fix up later if necessary.

I converted bit ops atomic_hash lock to raw_spinlock_t. Doing so avoids
some ugly nesting of linux/*.h and asm/*.h files. Those particular locks
are well tested and contained entirely inside arch specific code. I do NOT
expect any new issues to arise with them.

If someone does ever need to use debug/metrics with them, then they will
need to unravel this hairball between spinlocks, atomic ops, and bit ops
that exist only because parisc has exactly one atomic instruction: LDCW
(load and clear word).

From: "Luck, Tony" <tony.luck@intel.com>

ia64 fix

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjanv@infradead.org>
Signed-off-by: Grant Grundler <grundler@parisc-linux.org>
Cc: Matthew Wilcox <willy@debian.org>
Signed-off-by: Hirokazu Takata <takata@linux-m32r.org>
Signed-off-by: Mikael Pettersson <mikpe@csd.uu.se>
Signed-off-by: Benoit Boissinot <benoit.boissinot@ens-lyon.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] s390: spin lock retry

Split spin lock and r/w lock implementation into a single try which is done
inline and an out of line function that repeatedly tries to get the lock
before doing the cpu_relax(). Add a system control to set the number of
retries before a cpu is yielded.

The reason for the spin lock retry is that the diagnose 0x44 that is used to
give up the virtual cpu is quite expensive. For spin locks that are held only
for a short period of time the costs of the diagnoses outweights the savings
for spin locks that are held for a longer timer. The default retry count is
1000.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>