linux(4): Remove sys/cdefs.h inclusion where it's not needed due to 685dc743

sys: Remove $FreeBSD$: one-line .c pattern

Remove /^[\s*]*__FBSDID\("\$FreeBSD\$"\);?\s*\n/

Revert "linux(4): The futex_wait operation should restart."

This reverts commit 5eec19c8eb0e1afafd7290325c61611c9a13b621 due to its
wrong. Linux interrupts futex syscall on signal and return EINTR.

spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD

The SPDX folks have obsoleted the BSD-2-Clause-FreeBSD identifier. Catch
up to that fact and revert to their recommended match of BSD-2-Clause.

Discussed with: pfg
MFC After: 3 days
Sponsored by: Netflix

linux(4): Rename linux_timer.h to linux_time.h

To avoid confusing people, rename linux_timer.h to linux_time.h,
as linux_timer.c is the implementation of timer syscalls only,
while linux_time.c contains implementation of all stuff declared
in linux_time.h.

MFC after: 2 weeks

linux(4): Cleanup includes under compat/linux

Cleanup unneeded includes, sort the rest according to style(9).
No functional changes.

MFC after: 2 weeks

linux(4): Cleanup sys/sysent.h from linux_util

Include sys/sysent.h directly where it needed. The linux_util.h included
in a most source files of the Linuxulator, avoid collecting a rarely used
includes here.

MFC after: 2 weeks

linux(4): Get rid of the opt_compat.h include.

Since e013e369 COMPAT_LINUX, COMPAT_LINUX32 build options are removed,
so include of opt_compat.h is no more needed.

MFC after: 2 weeks

linux(4): Fix get_robust_list() syscall return value.

The system call returns the head of the robust futex list. The list head is stored
in the location pointed to by the head argument. When copying data between address
spaces use proper head storage size as it depends on an emulated ABI.

PR: 267616
MFC after: 3 days

linux(4): To improve readability use FUTEX_UNOWNED instead of 0

MFC after: 2 weeks

linux(4): Handle cas failure on ll/sc operations

Follow the 11a6ecd4. Check and handle the case when the ll/sc casu fails
even when the compare succeeds.

For more details PR/263825, https://reviews.freebsd.org/D35150.

Obtained from: Andrew@
MFC after: 2 weeks

linux(4); Style.

MFC after: 2 weeks

linux(4): Return native error from futex_atomic_op to avoid conversion by the caller.

MFC after: 2 weeks

linux(4): The futex_wait operation should restart.

It's ok from the futex_wait perspective as umtxq_sleep method uses
absolute sleep timeout.

MFC after: 2 weeks

linux(4): Add a helper intended for copying timespec's from the userspace.

There are many places where we copyin Linux timespec from the userspace
and then convert it to the kernel timespec. To avoid code duplication
add a tiny halper for doing this.

MFC after: 2 weeks

linux(4): Improve comment.

Reported by: pfg
MFC after: 2 weeks

linux(4): Fix futex copyrights.

As no more NetBSD code in futexes exists replace NetBSD copyrights by
standard FreeBSD 2 clause license.
Add Roman Divacky's copyrights as an author of the robust futexes.

Differential revision: https://reviews.freebsd.org/D31347
MFC after: 2 weeks

linux(4): Eliminate a now unused includes after futexes refactoring.

MFC after: 2 weeks

linux(4): Add a comment about wait/requeue pi operations.

MFC after: 2 weeks

linux(4): Handle incorrect FUTEX_CLOCK_REALTIME option bit.

Return ENOSYS if the FUTEX_CLOCK_REALTIME option bit is specified for an
inappropriate futex operation.

MFC after: 2 weeks

linux(4): Handle FUTEX_LOCK_PI2 oeration.

FUTEX_LOCK_PI2 was added to support clock selection as FUTEX_LOCK_PI uses a
CLOCK_REALTIME based absolute value since it was implemented, but it does not
require that the FUTEX_CLOCK_REALTIME bit is set, because that was introduced
later.

MFC after: 2 weeks

linux(4): Use variable name not type for sizeof() to calculate storage size.

MFC after: 2 weeks

linux(4): Move len variable initialization to the appropriate place.

MFC after: 2 weeks

linux(4): Use linux_tdfind() in get_robust_list.

In the Linux emulation layer linux_tdfind() has a special purpose to
handle glibc specific TID mangling and we should use it instead of tdfind().

MFC after: 2 weeks

linux(4): Eliminate unnecessary error initialization.

MFC after: 2 weeks

linux(4): Eliminate unnecessary head initialization.

MFC after: 2 weeks

linux(4): style, wrap too long line.

MFC after: 2 weeks

linux(4): Eliminating remnants of futex sdt.

MFC after: 2 weeks

linux(4): Handle special case for regular futex in handle_futex_death().

Handle some races in handle_futex_death() which can prevents a wakeup of
potential waiters which can cause these waiters to block forever.

Differential Revision: https://reviews.freebsd.org/D31280
MFC after: 2 weeks

linux(4): Futex address must be 32-bit aligned.

Linux futex documentation explicitly states that EINVAL is returned if
the futex is not 4-byte aligned. Check futex alignment as a Linux do
and return EINVAL.

Differential Revision: https://reviews.freebsd.org/D31279
MFC after: 2 weeks

linux(4): Finish cf8d74e3fe63.

Add forgotten val3_compare initialization in case of time64 futex.

MFC after: 2 weeks

linux(4): Replace casuword32 by casueword32.

Follow the r349951 (30b3018d), add check to react to stops and requests
to terminate between retries.

Reviewed by: kib
Differential Revision: https://reviews.freebsd.org/D31254
MFC after: 2 weeks

linux(4): Implement pi futexes using umtx.

Differential Revision: https://reviews.freebsd.org/D31240
MFC after: 2 weeks

linux(4): Replace copyin() by fueword32() in handle_futex_death().

According to fetch(9) fueword facility designed to fetch atomically
small amount of data from user space.

Reviewed by: kib
Differential Revision: https://reviews.freebsd.org/D31239
MFC after: 2 weeks

linux(4): Reimplement futexes using umtx.

Differential Revision: https://reviews.freebsd.org/D31236
MFC after: 2 weeks

umtx: Split umtx.h on two counterparts.

To prevent umtx.h polluting by future changes split it on two headers:
umtx.h - ABI header for userspace;
umtxvar.h - the kernel staff.

While here fix umtx_key_match style.

Reviewed by: kib
Differential Revision: https://reviews.freebsd.org/D31248
MFC after: 2 weeks

linux(4): Factor out the futex_wait() op into linux_futex_wait().

MFC after: 2 weeks

linux(4): Prevent an endless loop.

In the futex_atomic_op() the encoded_op is a user-supplied parameter.
If the user specifies an incorrect value for this parameter paired with a valid
*uaddr parameter the caller will go into the endless loop. To prevent this check
futex_atomic_op() result and break the loop in case of ENOSYS.

MFC after: 2 weeks

linux(4): Eliminate bogus comment.

For the caller is no need for access checking here, as the caller must take care
of EFAULT handling. Moreover, this check would be superfluous, since EFAULT is
extremily rare, and we prefer the fast path.

MFC after: 2 weeks

linux(4): Allow musl brand to use FUTEX_REQUEUE op.

Initial patch from submitter was adapted by me to prevent unconditional
FUTEX_REQUEUE use.

PR: 255947
Submitted by: Philippe Michaud-Boudreault
Differential Revision: https://reviews.freebsd.org/D30332

linux(4): Factor out the FUTEX_WAKE_OP op into linux_futex_wakeop().

MFC after: 2 weeks

linux(4): Factor out the FUTEX_CMP_REQUEUE op into linux_futex_requeue().

MFC after: 2 weeks

linux(4): Factor out the FUTEX_WAKE op into linux_futex_wake().

MFC after: 2 weeks

linux(4): Factor out the FUTEX_WAIT op into linux_futex_wait().

MFC after: 2 weeks

linux(4): Refactor the struct linux_futex_args.

Move flags and rtclock to the struct linux_futex_args. This will be used when
I split linux_futex() into separate futex op functions.

MFC after: 2 weeks

Drop "All rights reserved" from my copyright statements.

Add email and fixup years while here.

Reviewed by: imp
Differential Revision: https://reviews.freebsd.org/D30912
MFC after: 2 weeks

linux(4): Implement futex_time64 system call.

MFC after: 2 weeks

linux(4): Prevent integer overflow in futex_requeue.

To prevent a signed integer overflow in futex_requeue add a sanity check
to catch negative values of nrwake or nrrequeue.

MFC after: 2 weeks

linux: remove redundant SDT tracepoints

Remove all the 'entry' and 'return' probes; they clutter up the source
and are redundant to FBT.

Reviewed By: dchagin
Sponsored By: EPSRC
Differential Revision: https://reviews.freebsd.org/D30040

compat: clean up empty lines in .c and .h files

Fix a lock leak when emulating futex(FUTEX_WAIT_BITSET).

Reported by: syzkaller
MFC after: 1 week
Sponsored by: The FreeBSD Foundation

Don't use newlines with linux_msg(). No functional changes.

MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation

Improve the warnings.

MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation

linux futex_put(): do not touch futex after dropping our reference.

Reported and tested by: Steve Roome <me@stephenroome.com>
Sponsored by: The FreeBSD Foundation
MFC after: 1 week

linux: futex_mtx should follow futex_list

Move futex_mtx to linux_common.ko for amd64 and aarch64 along
with respective list/mutex init/destroy.

PR: 240989
Reported by: Alex S <iwtcex@gmail.com>

linux: provide just one instance of futex_list

Move futex_list definition to linux.c which is included once
in linux.ko (i386) and in linux_common.ko (amd64 and aarch64)
allowing 32/64 bit linux programs to access the same futexes
in the latter case.

PR: 240989
Reviewed by: dchagin
Differential Revision: https://reviews.freebsd.org/D22073

Make timespecadd(3) and friends public

The timespecadd(3) family of macros were imported from NetBSD back in
r35029. However, they were initially guarded by #ifdef _KERNEL. In the
meantime, we have grown at least 28 syscalls that use timespecs in some
way, leading many programs both inside and outside of the base system to
redefine those macros. It's better just to make the definitions public.

Our kernel currently defines two-argument versions of timespecadd and
timespecsub. NetBSD, OpenBSD, and FreeDesktop.org's libbsd, however, define
three-argument versions. Solaris also defines a three-argument version, but
only in its kernel. This revision changes our definition to match the
common three-argument version.

Bump _FreeBSD_version due to the breaking KPI change.

Discussed with: cem, jilles, ian, bde
Differential Revision: https://reviews.freebsd.org/D14725

Fix futexes on i386 after the 4/4G split.

Use proper method to access userspace. For now, only the slow copyout
path is implemented.

Reported and tested by: tijl (previous version)
Sponsored by: The FreeBSD Foundation

sys/compat: further adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error
prone - task.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

Fix NULL pointer dereference in futex_wake_op() in case when the same
address specified for arguments uaddr and uaddr2.

PR: 218987
Reported by: luke.tw gmail
MFC after: 1 week

Remove excess tv_nsec test as this is done by linux_to_native_timespec().

MFC after: 1 week

For future use move futex timeout code to the separate function and
switch to the high resolution sbintime_t.

MFC after: 1 week

Due to lack the priority propagation feature replace sx by mutex. WIth this
commit NPTL tests are ends in 1 minute faster.

MFC after: 1 week

Add my copyright as I rewrote most of the futex code. Minor style(9) cleanup
while here.

MFC after: 1 week

Change linux get_robust_list system call to match actual linux one.

The set_robust_list system call request the kernel to record the head
of the list of robust futexes owned by the calling thread. The head
argument is the list head to record.
The get_robust_list system call should return the head of the robust
list of the thread whose thread id is specified in pid argument.
The list head should be stored in the location pointed to by head
argument.

In contrast, our implemenattion of get_robust_list system call copies
the known portion of memory pointed by recorded in set_robust_list
system call pointer to the head of the robust list to the location
pointed by head argument.

So, it is possible for a local attacker to read portions of kernel
memory, which may result in a privilege escalation.

Submitted by: mjg
Security: SA-16:03.linux

Unlock process lock when return error from getrobustlist call and add
an forgotten dtrace probe when return the same error.

MFC after: 3 days
XMFC with: r292743

Do not allow access to emuldata for non Linux processes.

Pointed out by: mjg@
Security: https://admbugs.freebsd.org/show_bug.cgi?id=679

Do not use struct l_timespec without conversion. While here move
args->timeout handling before acquiring the futex key at FUTEX_WAIT path.

Differential Revision: https://reviews.freebsd.org/D1520
Reviewed by: trasz

Add prototypes for static futex functions.

Differential Revision: https://reviews.freebsd.org/D1519
Reviewed by: trasz

Print out unsupported futex operation message only once for the process.

Differential Revision: https://reviews.freebsd.org/D1498

Where possible we will use M_LINUX malloc(9) type.
Move M_FUTEX defines to the linux_common.ko.

Differential Revision: https://reviews.freebsd.org/D1077
Reviewed by: emaste

Refund the proc emuldata struct for future use. For now move flags from
thread emuldata to proc emuldata as it was originally intended.

As we can have both 64 & 32 bit Linuxulator running any eventhandler
can be called twice for us. To prevent this move eventhandlers code
from linux_emul.c to the linux_common.ko module.

Differential Revision: https://reviews.freebsd.org/D1073

Switch linuxulator to use the native 1:1 threads.

The reasons:
1. Get rid of the stubs/quirks with process dethreading,
process reparent when the process group leader exits and close
to this problems on wait(), waitpid(), etc.
2. Reuse our kernel code instead of writing excessive thread
managment routines in Linuxulator.

Implementation details:

1. The thread is created via kern_thr_new() in the clone() call with
the CLONE_THREAD parameter. Thus, everything else is a process.
2. The test that the process has a threads is done via P_HADTHREADS
bit p_flag of struct proc.
3. Per thread emulator state data structure is now located in the
struct thread and freed in the thread_dtor() hook.
Mandatory holdig of the p_mtx required when referencing emuldata
from the other threads.
4. PID mangling has changed. Now Linux pid is the native tid
and Linux tgid is the native pid, with the exception of the first
thread in the process where tid and pid are one and the same.

Ugliness:

In case when the Linux thread is the initial thread in the thread
group thread id is equal to the process id. Glibc depends on this
magic (assert in pthread_getattr_np.c). So for system calls that
take thread id as a parameter we should use the special method
to reference struct thread.

Differential Revision: https://reviews.freebsd.org/D1039

Fix Clang warning: passing 'unsigned int *' to parameter of type 'int *' converts between pointers to integer types with different sign.

MFC after: 1 week

Glibc was switched to the FUTEX_WAIT_BITSET op and CLOCK_REALTIME
flag has been added instead of FUTEX_WAIT to replace the FUTEX_WAIT
logic which needs to do gettimeofday() calls before the futex syscall
to convert the absolute timeout to a relative timeout.
Before this the CLOCK_MONOTONIC used by the FUTEX_WAIT_BITSET op.

When the FUTEX_CLOCK_REALTIME is specified the timeout is an absolute
time, not a relative time. Rework futex_wait to handle this.
On the side fix the futex leak in error case and remove useless
parentheses.

Properly calculate the timeout for the CLOCK_MONOTONIC case.

MFC after: 3 days

In r218101 I have not changed properly the futex syscall definition.
Some Linux futex ops atomically verifies that the futex address uaddr
(uval) contains the value val. Comparing signed uval and unsigned val
may lead to an unexpected result, mostly to a deadlock.

So copyin uaddr to an unsigned int to compare the parameters correctly.

While here change ktr records to print parameters in more readable format.

Tested by eadler@

MFC after: 3 days

- For kernel compiled only with KDTRACE_HOOKS and not any lock debugging
option, unbreak the lock tracing release semantic by embedding
calls to LOCKSTAT_PROFILE_RELEASE_LOCK() direclty in the inlined
version of the releasing functions for mutex, rwlock and sxlock.
Failing to do so skips the lockstat_probe_func invokation for
unlocking.
- As part of the LOCKSTAT support is inlined in mutex operation, for
kernel compiled without lock debugging options, potentially every
consumer must be compiled including opt_kdtrace.h.
Fix this by moving KDTRACE_HOOKS into opt_global.h and remove the
dependency by opt_kdtrace.h for all files, as now only KDTRACE_FRAMES
is linked there and it is only used as a compile-time stub [0].

[0] immediately shows some new bug as DTRACE-derived support for debug
in sfxge is broken and it was never really tested. As it was not
including correctly opt_kdtrace.h before it was never enabled so it
was kept broken for a while. Fix this by using a protection stub,
leaving sfxge driver authors the responsibility for fixing it
appropriately [1].

Sponsored by: EMC / Isilon storage division
Discussed with: rstone
[0] Reported by: rstone
[1] Discussed with: philip

Fix some typos that were causing probe argument types to show up as unknown.

Reviewed by: rwatson (mac provider)
Approved by: re (glebius)
MFC after: 1 week

Arithmetic on pointers takes into account the size of the type. Properly cast the pointer to avoid incorrect pointer scaling.

MFC after: 1 Week

- >500 static DTrace probes for the linuxulator
- DTrace scripts to check for errors, performance, ...
they serve mostly as examples of what you can do with the static probe;s
with moderate load the scripts may be overwhelmed, excessive lock-tracing
may influence program behavior (see the last design decission)

Design decissions:
- use "linuxulator" as the provider for the native bitsize; add the
bitsize for the non-native emulation (e.g. "linuxuator32" on amd64)
- Add probes only for locks which are acquired in one function and released
in another function. Locks which are aquired and released in the same
function should be easy to pair in the code, inter-function
locking is more easy to verify in DTrace.
- Probes for locks should be fired after locking and before releasing to
prevent races (to provide data/function stability in DTrace, see the
man-page of "dtrace -v ..." and the corresponding DTrace docs).

Mark MALLOC_DEFINEs static that have no corresponding MALLOC_DECLAREs.

This means that their use is restricted to a single C file.

Remove now-obsolete comment.

Submitted by: netchild
MFC after: 1 week

Print out shared flag for debug purpose.

MFC after: 1 Week

Switch PROCESS_SHARE to AUTO_SHARE (as umtx do). Even for SHARED,
if page mapped MAP_ANON linux uses private algorithm too.

Disscussed with: jhb

MFC after: 3 Days

Use umtx_key objects to uniquely identify futexes. Private futexes in
different processes that happen to use the same user address in the
separate processes will now be treated as distinct futexes rather than the
same futex. We can now honor shared futexes properly by mapping them to a
PROCESS_SHARED umtx_key. Private futexes use THREAD_SHARED umtx_key
objects.

In conjunction with: dchagin
Reviewed by: kib
MFC after: 1 week

Style(9) fix. Do not initialize variables in the declarations.

Sort include files in the alphabetical order.

Remove comment about 'ftlk' LOR.

Stop printing the LOR, as this is expected behavior.

The bitset field of freshly created futex should be initialized explicity.
Otherwise, REQUEUE operations fails.

Rename used_requeue and use it as bitwise field to store more flags.
Reimplement used_requeue logic with LINUX_XDEPR_REQUEUEOP flag.

Yet another unimplemented futex operation, print out about.

Submitted by: arundel
MFC after: 1 month.

Implement a futex BITSET op.

Submitted by: arundel
MFC after: 1 month.

Remove trailing dot from the unimplemented futex messages to make
them consistent with the syscall and ipc messages.

Submitted by: arundel
MFC after: 3 days

Some style(9) fixes.

Submitted by: arundel
MFC after: 1 week

- print out the PID and program name of the program trying to use an
unsupported futex operation
- for those futex operations which are known to be not supported,
print out which futex operation it is
- shortcut the error return of the unsupported FUTEX_CLOCK_REALTIME in
some cases:
FUTEX_CLOCK_REALTIME can be used to tell linux to use
CLOCK_REALTIME instead of CLOCK_MONOTONIC. FUTEX_CLOCK_REALTIME
however must only be set, if either FUTEX_WAIT_BITSET or
FUTEX_WAIT_REQUEUE_PI are set too. If that's not the case
we can die with ENOSYS right at the beginning.

Submitted by: arundel
Reviewed by: rdivacky (earlier iteration of the patch)
MFC after: 1 week

A new jail(8) with a configuration file, to replace the work currently done
by /etc/rc.d/jail.

Simplify timeout check in futex_wait() using itimerfix() and return error
if the given timeout is invalid. Consistently use int type for timeout and
correct a format string in futex_sleep().

Fix a comparision of an uninitialised pointer.

Submitted by: arundel
Found by: clang analysis (automatic service by uqs@)
Reviewed by: rdivacky

MFC a number of changes from head for ISP (203478,203463,203444,202418,201758,
201408,201325,200089,198822,197373,197372,197214,196162). Since one of those
changes was a semicolon cleanup from somebody else, this touches a lot more.

Remove extraneous semicolons, no functional changes.

Submitted by: Marc Balmer <marc@msys.ch>
MFC after: 1 week

Unlock process lock when return error from getrobustlist call.

Tested by: Alexander Best <alexbestms at math uni-muenster de>
Approved by: kib (mentor)
MFC after: 3 days

Add KTR(9) tracing for futex emulation.

Approved by: kib (mentor)
MFC after: 1 month

Move extern variable definitions to the header file.

Approved by: kib (mentor)
MFC after: 1 month

Reimplement futexes.
Old implemention used Giant to protect the kernel data structures,
but at the same time called malloc(M_WAITOK), that could cause the
calling thread to sleep and lost Giant protection. User-visible
result was the missed wakeup.

New implementation uses one sx lock per futex. The sx protects
the futex structures and allows to sleep while copyin or copyout
are performed.

Unlike linux, we return EINVAL when FUTEX_CMP_REQUEUE operation
is requested and either caller specified futexes are equial or
second futex already exists. This is acceptable since the situation
can only occur from the application error, and glibc falls back to
old FUTEX_WAKE operation when FUTEX_CMP_REQUEUE returns an error.

Approved by: kib (mentor)
MFC after: 1 month

Remove support for FUTEX_REQUEUE operation.
Glibc does not use this operation since 2.3.3 version (Jun 2004),
as it is racy and replaced by FUTEX_CMP_REQUEUE operation.
Glibc versions prior to 2.3.3 fall back to FUTEX_WAKE when
FUTEX_REQUEUE returned EINVAL.

Any application directly using FUTEX_REQUEUE without return
value checking are definitely broken.

Limit quantity of messages per process about unsupported
operation.

Approved by: kib (mentor)
MFC after: 1 month

Sort include files in the alphabetical order.

Approved by: kib (mentor)
MFC after: 2 weeks

Ignore FUTEX_FD op, as it is done by linux.

Approved by: kib (mentor)
MFC after: 2 weeks

Include linux_futex.h before linux_emul.h

Approved by: kib (mentor)
MFC after: 6 days

In the robust futexes list head, futex_offset shall be signed,
and glibc actually supplies negative offsets. Change l_ulong to l_long.

Submitted by: dchagin

- Import the HEAD csup code which is the basis for the cvsmode work.

Make robust futexes work on linux32/amd64. Use PTRIN to read
user-mode pointers. Change types used in the structures definitions to
properly-sized architecture-specific types.

Submitted by: dchagin
MFC after: 1 week

Implement robust futexes. Most of the code is modelled after
what Linux does. This is because robust futexes are mostly
userspace thing which we cannot alter. Two syscalls maintain
pointer to userspace list and when process exits a routine
walks this list waking up processes sleeping on futexes
from that list.

Reviewed by: kib (mentor)
MFC after: 1 month

o Add stub support for some new futex operations,
so the annoying message is not printed.

o Don't warn about FUTEX_FD not being implemented
and return ENOSYS instead of 0 (eg. success).

o Clear FUTEX_PRIVATE_FLAG as we actually implement
only private futexes so there is no reason to
return ENOSYS when app asks for a private futex.
We don't reject shared futexes because they worked
just fine with our implementation so far.

Approved by: kib (mentor)
Tested by: bsam
MFC after: 1 week

Return ENOSYS instead of 0 for the unknown futex operations.

Submitted by: rdivacky
Reported and tested by: Gary Stanley <gary velocity-servers net>

Move futex support code from <arch>/support.s into linux compat directory.
Implement all futex atomic operations in assembler to not depend on the
fuword() that does not allow to distinguish between -1 and failure return.
Correctly return 0 from atomic operations on success.

In collaboration with: rdivacky
Tested by: Scot Hetzel <swhetzel gmail com>, Milos Vyletel <mvyletel mzm cz>
Sponsored by: Google SoC 2007

MFP4: Linux futex support for amd64.

Initial patch was submitted by kib and additional work was done
by Divacky Roman.

Tested by: emulation

MFp4 (110541):
Sync with rev 1.7 in NetBSD.

Obtained from: NetBSD

MFp4 (110523, parts which apply cleanly):
semi-automatic style(9)

The futex stuff already differs a lot (only a small part does not differ)
from NetBSD, so we are already way off and can't apply changes from NetBSD
automatically. As we need to merge everything by hand already, we can even
make the files comply to our world order.

Change futex lock from mutex to sx. Make futex_get atomic (protected by the
futex lock).

Sponsored by: Google SoC 2006
Submitted by: rdivacky
Suggested by: jhb

- don't wake every sleeper just the first one [1]
- remove debuging printf [2]

Submitted by: intron <mag@intron.ac> [1], rdivacky [2]

Correct the number of retries in a futex_wake() call.

Sponsored by: Google SoC 2006
Submitted by: rdivacky

ifdef DEBUG a printf

Submitted by: rdivacky

Fix the DEBUG build:
- linux_emul.c [1]
- linux_futex.c [2]

Sponsored by: Google SoC 2006 [1]
Submitted by: rdivacky [1]
netchild [2]

Add some new files needed for linux 2.6.x compatibility.

Please don't style(9) the NetBSD code, we want to stay in sync. Not imported
on a vendor branch since we need local changes.

Sponsored by: Google SoC 2006
Submitted by: rdivacky
With help from: manu@NetBSD.org
Obtained from: NetBSD (linux_{futex,time}.*)