CVS log for src/sys/kern/kern_fork.c

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Default branch: MAIN

fix recently committed typos by msaitoh in few more places, as well as few more.
mainly s/contigous/contiguous/ and s/miliseconds/milliseconds/ in comments.

Trailing whitespace

Uglify code to fix build.

fork(2): Plug leaks in proc_alloc error branch.

Changes to make EVFILT_PROC MP-safe:

Because the locking protocol around processes is somewhat complex
compared to other events that can be posted on kqueues, introduce
new functions for posting NOTE_EXEC, NOTE_EXIT, and NOTE_FORK,
rather than just using the generic knote() function.  These functions
KASSERT() their locking expectations, and deal with other complexities
for each situation.

knote_proc_fork(), in particiular, needs to handle NOTE_TRACK, which
requires allocation of a new knote to attach to the child process.  We
don't want to be allocating memory while holding the parent's p_lock.
Furthermore, we also have to attach the tracking note to the child
process, which means we have to acquire the child's p_lock.

So, to handle all this, we introduce some additional synchronization
infrastructure around the 'knote' structure:

- Add the ability to mark a knote as being in a state of flux.  Knotes
  in this state are guaranteed not to be detached/deleted, thus allowing
  a code path drop other locks after putting a knote in this state.

- Code paths that wish to detach/delete a knote must first check if the
  knote is in-flux.  If so, they must wait for it to quiesce.  Because
  multiple threads of execution may attempt this concurrently, a mechanism
  exists for a single LWP to claim the detach responsibility; all other
  threads simply wait for the knote to disappear before they can make
  further progress.

- When kqueue_scan() encounters an in-flux knote, it simply treats the
  situation just like encountering another thread's queue marker -- wait
  for the flux to settle and continue on.

(The "in-flux knote" idea was inspired by FreeBSD, but this works differently
from their implementation, as the two kqueue implementations have diverged
quite a bit.)

knote_proc_fork() uses this infrastructure to implement NOTE_TRACK like so:

- Attempt to put the original tracking knote into a state of flux; if this
  fails (because the note has a detach pending), we skip all processing
  (the original process has lost interest, and we simply won the race).

- Once the note is in-flux, drop the kq and forking process's locks, and
  allocate 2 knotes: one to post the NOTE_CHILD event, and one to attach
  a new NOTE_TRACK to the child process.  Notably, we do NOT go through
  kqueue_register() to do this, but rather do all of the work directly
  and KASSERT() our assumptions; this allows us to directly control our
  interaction with locks.  All memory allocations here are performed with
  KM_NOSLEEP, in order to prevent holding the original knote in-flux
  indefinitely.

- Because the NOTE_TRACK use case adds knotes to kqueues through a
  sort of back-door mechanism, we must serialize with the closing of
  the destination kqueue's file descriptor, so steal another bit from
  the kq_count field to notify other threads that a kqueue is on its
  way out to prevent new knotes from being enqueued while the close
  path detaches them.

In addition to fixing EVFILT_PROC's reliance on KERNEL_LOCK, this also
fixes a long-standing bug whereby a NOTE_CHILD event could be dropped
if the child process exited before the interested process received the
NOTE_CHILD event (the same knote would be used to deliver the NOTE_EXIT
event, and would clobber the NOTE_CHILD's 'data' field).

Add a bunch of comments to explain what's going on in various critical
sections, and sprinkle additional KASSERT()s to validate assumptions
in several more locations.

Move proc_lock into the data segment.  It was dynamically allocated because
at the time we had mutex_obj_alloc() but not __cacheline_aligned.

Remove the stub support of CLONE_PID in clone(2)

CLONE_PID causes the child clonee to share the same process id as cloner.

It was implemented for debugging purposes in the Linux kernel 2.0,
restricted to root only in 2.3.21 and removed from Linux 2.5.16.

The CLONE_PID bit was recycled for CLONE_PIDFD in Linux 5.2.

On debugger attach to a prestarted process don't report SIGTRAP

Introduce PSL_TRACEDCHILD that indicates tracking of birth of a process.
A freshly forked process checks whether it is traced and if so, reports
SIGTRAP + TRAP_CHLD event to a debugger as a result of tracking forks-like
events. There is a time window when a debugger can attach to a newly
created process and receive SIGTRAP + TRAP_CHLD instead of SIGSTOP.

Fixes races in t_ptrace_wait* tests when a test hangs or misbehaves,
especially the ones reported in tracer_sysctl_lookup_without_duplicates.

Sync with bouyer-xenpvh-base2 (HEAD)

Overhaul the way LWP IDs are allocated.  Instead of each LWP having it's
own LWP ID space, LWP IDs came from the same number space as PIDs.  The
lead LWP of a process gets the PID as its LID.  If a multi-LWP process's
lead LWP exits, the PID persists for the process.

In addition to providing system-wide unique thread IDs, this also lets us
eliminate the per-process LWP radix tree, and some associated locks.

Remove the separate "global thread ID" map added previously; it is no longer
needed to provide this functionality.

Nudged in this direction by ad@ and chs@.

Sync with HEAD

Sync with HEAD

Set p_oppid always, not just when a parent is traced

PR kern/55151 by Martin Husemann

Mostly merge changes from HEAD upto 20200411

Reintroduce struct proc::p_oppid

Relying on p_opptr is not safe as there is a race between:
 - spawner giving a birth to a child process and being killed
 - spawnee accessng p_opptr and reporting TRAP_CHLD

PR kern/54786 by Andreas Gustafsson

- Untangle spawn_return by splitting it up to sub-functions.
- Merge the eventswitch parent notification code which was copied in two
  places (eventswitchchild)
- Fix bugs in the eventswitch parent notification code:
  1. p_slflags should be accessed holding both proc_lock and p->p_lock
  2. p->p_opptr can be NULL if the parent was PSL_CHTRACED and exited.

Fixes random crashes the posix_spawn_kill_spawner unit test which tried
to dereference a NULL pptr.

child_return():

- This was assuming arg == curlwp, but NULL is passed to lwp_create(), as
  evidenced by a random panic during testing.  How did this ever work?

- Replace a goto.

Sync with head.

- Track LWPs in a per-process radixtree.  It uses no extra memory in the
  single threaded case.  Replace scans of p->p_lwps with lookups in the
  tree.  Find free LIDs for new LWPs in the tree.  Replace the hashed sleep
  queues for park/unpark with lookups in the tree under cover of a RW lock.

- lwp_wait(): if waiting on a specific LWP, find the LWP via tree lookup and
  return EINVAL if it's detached, not ESRCH.

- Group the locks in struct proc at the end of the struct in their own cache
  line.

- Add some comments.

- Extend the per-CPU counters matt@ did to include all of the hot counters
  in UVM, excluding uvmexp.free, which needs special treatment and will be
  done with a separate commit.  Cuts system time for a build by 20-25% on
  a 48 CPU machine w/DIAGNOSTIC.

- Avoid 64-bit integer divide on every fault (for rnd_add_uint32).

Minor scheduler cleanup:

- Adapt to cpu_need_resched() changes. Avoid lost & duplicate IPIs and ASTs.
  sched_resched_cpu() and sched_resched_lwp() contain the logic for this.
- Changes for LSIDL to make the locking scheme match the intended design.
- Reduce lock contention and false sharing further.
- Numerous small bugfixes, including some corrections for SCHED_FIFO/RT.
- Use setrunnable() in more places, and merge cut & pasted code.

Pull up following revision(s) (requested by kamil in ticket #311):

	sys/sys/siginfo.h: revision 1.34
	sys/kern/sys_ptrace_common.c: revision 1.59
	sys/kern/sys_lwp.c: revision 1.70
	sys/compat/sys/siginfo.h: revision 1.8
	sys/kern/kern_sig.c: revision 1.365
	sys/kern/kern_lwp.c: revision 1.203
	sys/sys/signalvar.h: revision 1.96
	sys/kern/kern_exec.c: revision 1.482
	sys/kern/kern_fork.c: revision 1.214

Move TRAP_CHLD/TRAP_LWP ptrace information from struct proc to siginfo

Storing struct ptrace_state information inside struct proc was vulnerable
to synchronization bugs, as multiple events emitted in the same time were
overwritting other ones.

Cache the original parent process id in p_oppid. Reusing here p_opptr is
in theory prone to slight race codition.

Change the semantics of PT_GET_PROCESS_STATE, reutning EINVAL for calls
prompting for the value in cases when there wasn't registered an
appropriate event.

Add an alternative approach to check the ptrace_state information, directly
from the siginfo_t value returned from PT_GET_SIGINFO. The original
PT_GET_PROCESS_STATE approach is kept for compat with older NetBSD and
OpenBSD. New code is recommended to keep using PT_GET_PROCESS_STATE.
Add a couple of compile-time asserts for assumptions in the code.

No functional change intended in existing ptrace(2) software.

All ATF ptrace(2) and ATF GDB tests pass.

This change improves reliability of the threading ptrace(2) code.

Remove p_oppid from struct proc

This field is not needed as it duplicated p_opptr that is alread safe to
use, unless proven otherwise.

eventswitch() already contained a check for != initproc (pid1).

Ride ABI bump for 9.99.16.

Move TRAP_CHLD/TRAP_LWP ptrace information from struct proc to siginfo

Storing struct ptrace_state information inside struct proc was vulnerable
to synchronization bugs, as multiple events emitted in the same time were
overwritting other ones.

Cache the original parent process id in p_oppid. Reusing here p_opptr is
in theory prone to slight race codition.

Change the semantics of PT_GET_PROCESS_STATE, reutning EINVAL for calls
prompting for the value in cases when there wasn't registered an
appropriate event.

Add an alternative approach to check the ptrace_state information, directly
from the siginfo_t value returned from PT_GET_SIGINFO. The original
PT_GET_PROCESS_STATE approach is kept for compat with older NetBSD and
OpenBSD. New code is recommended to keep using PT_GET_PROCESS_STATE.

Add a couple of compile-time asserts for assumptions in the code.

No functional change intended in existing ptrace(2) software.

All ATF ptrace(2) and ATF GDB tests pass.

This change improves reliability of the threading ptrace(2) code.

Correct use-after-free issue in vfork(2)

In the previous behavior vforking parent was keeping pointer to a child
and checking whether it clears a PL_PPWAIT in its bitfield p_lflag. However
a child can go invalid between exec/exit event from child and waking up
vforked parent and this can cause invalid pointer read and in the worst
scenario kernel crash.

In the new behavior vforked child keeps a reference to vforked parent LWP
and sets a value l_vforkwaiting to false. This means that vforked child
can finish its work, exec/exit and be terminated and once parent will be
woken up it will read its own field whether its child is still blocking.

Add new field in struct lwp: l_vforkwaiting protected by proc_lock.
In future it should be refactored and all PL_PPWAIT users transformed to
l_vforkwaiting and next l_vforkwaiting probably transformed into a bit
field.

This is another attempt of fixing this bug after <rmind> from 2012 in
commit:

Author: rmind <rmind@NetBSD.org>
Date:   Sun Jul 22 22:40:18 2012 +0000

    fork1: fix use-after-free problems.  Addresses PR/46128 from Andrew Doran.
    Note: PL_PPWAIT should be fully replaced and modificaiton of l_pflag by
    other LWP is undesirable, but this is enough for netbsd-6.

The new version no longer performs unsafe access in l_lflag changing the
LP_VFORKWAIT bit.

Verified with ATF t_vfork and t_ptrace* tests and they are no longer
causing any issues in my local setup.

Fixes PR/46128 by Andrew Doran

Sync with HEAD

Register KTR events for debugger related signals

Register signals for:

 - crashes (FPE, SEGV, FPE, ILL, BUS)
 - LWP events
 - CHLD (FORK/VFORK/VFORK_DONE) events -- temporarily disabled
 - EXEC events

While there refactor related functions in order to simplify the code.

Add missing comment documentation for recently added kernel functions.

Correct handling of corner cases in fork1(9) code under a debugger

Correct detaching and SIGKILLing forker and vforker in the middle of its
operation.

Add eventswitch() in signal code

Route all crash and debugger related signal through eventswitch(), that
calls sigswitch() with preprocessed arguments.

This code avoids code duplication and allows to introduce changes that
will affect all callers of sigswitch() in debugger-related events.

No functional change intended.

Add a paranoid racy lock check in child_return()

In theory a child could be detached for some reason or another during
the time window between checking for PSL_TRACED and acquiring proc_lock.

Acquire the proc_lock mutex and recheck for PSL_TRACED before emitting
SIGTRAP. sigswitch() must acquite it internally anyway so this does not
have a negative impact and adds an extra sanity check.

For !PSL_TRACED case there is no impact.

Centralized shared part of child_return() into MI part

Add a new function md_child_return() for MD specific bits only.

New child_return() is now part of MI and central code that handles
uniformly tracing code (KTR and ptrace(2)).

Synchronize value passed to ktrsysret() among ports to SYS_fork. This is
a traditional value and accessing p_lflag to check for PL_PPWAIT shall
use locking against proc_lock. Returning SYS_fork vs SYS_vfork still isn't
correct enough as there are more entry points to forking code. Instead of
making it too good, just settle with plain SYS_fork for all ports.

Correct distinguishing fork/vfork tracing event in fork1(9)

flags can contain a different value than FORK_PPWAIT and bit comparing
with '&&' was a typo.

Detected with __clone(2) usage scenarios.

Rework the fork(2)/vfork(2) event signalling under ptrace(2)

Remove the constraint of SIGTRAP event being maskable by a tracee.

Now all SIGTRAP TRAP_CHLD events are delivered to debugger.

This code touches MD specific logic and the child_return routine.
It's an intermediate step with a room for refactoring in future and
right now the least invasive approach. This allows to assert expected
behavior in already existing ATF tests and make the code prettier
in future keeping the same semantics. Probably there is a need for a MI
wrapper of child_return for shared functionality between ports.

Synch with HEAD

Implement PTRACE_VFORK

Add support for tracing vfork(2) events in the context of ptrace(2).

This API covers other frontends to fork1(9) like posix_spawn(2) or clone(2),
if they cause parent to wait for exec(2) or exit(2) of the child.

Changes:
 - Add new argument to sigswitch() determining whether we need to acquire
   the proc_lock or whether it's already held.
 - Refactor fork1(9) for fork(2) and vfork(2)-like events.
   Call sigswitch() from fork(1) for forking or vforking parent, instead of
   emitting kpsignal(9). We need to emit the signal and suspend the parent,
   returning to user and relock proc_lock.
 - Add missing prototype for proc_stop_done() in kern_sig.c.
 - Make sigswitch a public function accessible from other kernel code
   including <sys/signalvar.h>.
 - Remove an entry about unimplemented PTRACE_VFORK in the ptrace(2) man page.
 - Permin PTRACE_VFORK in the ptrace(2) frontend for userland.
 - Remove expected failure for unimplemented PTRACE_VFORK tests in the ATF
   ptrace(2) test-suite.
 - Relax signal routing constraints under a debugger for a vfork(2)ed child.
   This intended to protect from signaling a parent of a vfork(2)ed child that
   called PT_TRACE_ME, but wrongly misrouted other signals in vfork(2)
   use-cases.

Add XXX comments about still existing problems and future enhancements:
 - correct vfork(2) + PT_TRACE_ME handling.
 - fork1(2) handling of scenarios when a process is collected in valid but
   rare cases.

All ATF ptrace(2) fork[1-8] and vfork[1-8] tests pass.

Fix PR kern/51630 by Kamil Rytarowski (myself).

Sponsored by <The NetBSD Foundation>

Sync with HEAD

Remove the rnewprocp argument from fork1(9)

It's now unused and it can cause use-after-free scenarios as noted by
<Mateusz Guzik>.

Reference: http://mail-index.netbsd.org/tech-kern/2017/09/08/msg022267.html

Sponsored by <The NetBSD Foundation>

update from HEAD

Store full executable path in p->p_path as discussed in tech-kern.
This means that the full executable path is always available.

- exec_elf.c: use p->path to set AT_SUN_EXECNAME, and since this is
  always set, do so unconditionally.
- kern_exec.c: simplify pathexec, use kmem_strfree where appropriate
  and set p->p_path
- kern_exit.c: free p->p_path
- kern_fork.c: set p->p_path for the child.
- kern_proc.c: use p->p_path to return the executable pathname; the
  NULL check for p->p_path, should be a KASSERT?
- exec.h: gc ep_path, it is not used anymore
- param.h: bump version, 'struct proc' size change

TODO:
1. reference count the path string, to save copy at fork and free
   just before exec?
2. canonicalize the pathname by changing namei() to LOCKPARENT
   vnode and then using getcwd() on the parent directory?

Sync with HEAD

Sync with HEAD

Sync with HEAD

- Propagate the signal mask from the ucontext_t to the newly created thread
  as specified by _lwp_create(2)
- Reset the signal stack for threads created with _lwp_create(2)

spaces to tab

PR kern/52117: move stop code for debuged children after fork into MI code.
XXX we might want to revisit this when handling the same event for vfork
better.

Sync with HEAD

Sync with HEAD

Add support for PTRACE_VFORK_DONE and stub for PTRACE_VFORK in ptrace(2)

PTRACE_VFORK is supposed to be used to track vfork(2)-like events, when
parent gives birth to new process child and stops till it exits or calls
exec().
Currently PTRACE_VFORK is a stub.

PTRACE_VFORK_DONE is notification to notify a debugger that a parent has
resumed after vfork(2)-like action.
PTRACE_VFORK_DONE throws SIGTRAP with TRAP_CHLD.

Sponsored by <The NetBSD Foundation>

Introduce new si_code for SIGTRAP: TRAP_CHLD - process child trap

The SIGTRAP signal is thrown from the kernel if EVENT_MASK (ptrace_event)
enables PTRACE_FORK. This new si_code helps debuggers to distinguish the
exact source of signal delivered for a debugger.

Another purpose of TRAP_CHLD is to retain the same behavior inside the
NetBSD kernel for process child traps and have an interface to monitor it.

Retrieving exact event and extended properties of process child trap is
available with PT_GET_PROCESS_STATE.

There is no behavior change for existing software.

This si_code value is NetBSD extension.

Sponsored by <The NetBSD Foundation>

Cleanup dead code after revert of racy vfork(2) commit

This removes dead code introduced with the following commit:

date: 2012-07-27 22:52:49 +0200;  author: christos;  state: Exp;  lines: +8 -2;
revert racy vfork() parent-blocking-before-child-execs-or-exits code.
ok rmind

Sync with HEAD.  (Note that most of these changes are simply $NetBSD$
tag issues.)

Sync with HEAD

deduplicate the complex lock reparent dance.

Sync with HEAD

When doing an unlock/relock dance to avoid lock inversion, it's important
to relock the lock you unlocked. Otherwise the lock you unlocked won't
walk the walk, not by a long chalk, and you'll end up getting mocked.

From Mateusz Guzik of FreeBSD via freenode.

XXX: pullup-6 and -7

Sync with HEAD (as of 26th Dec)

Change SDT (Statically Defined Tracing) probes to use link sets so that it
is easier to add probes. (From FreeBSD)

Rebase to HEAD as of a few days ago.

sync with head.

for a reference, the tree before this commit was tagged
as yamt-pagecache-tag8.

this commit was splitted into small chunks to avoid
a limitation of cvs.  ("Protocol error: too many arguments")

sync with head

convert vmem, signals, powerhooks from CIRCLEQ -> TAILQ.

resync from head

Add another field to the SDT_PROBE_DEFINE macro, so our DTrace probes
can named the same as those on other platforms.

For example, proc:::exec-success, not proc:::exec_success.

Implementation follows the same basic principle as FreeBSD's; add
another field to the SDT_PROBE_DEFINE macro which is the name
as exposed to userland.

sync with head

revert racy vfork() parent-blocking-before-child-execs-or-exits code.
ok rmind

fork1: fix use-after-free problems.  Addresses PR/46128 from Andrew Doran.
Note: PL_PPWAIT should be fully replaced and modificaiton of l_pflag by
other LWP is undesirable, but this is enough for netbsd-6.

sync with head

sync to latest -current.

Replace the remaining KAUTH_GENERIC_ISSUSER authorization calls with
something meaningful. All relevant documentation has been updated or
written.

Most of these changes were brought up in the following messages:

    http://mail-index.netbsd.org/tech-kern/2012/01/18/msg012490.html
    http://mail-index.netbsd.org/tech-kern/2012/01/19/msg012502.html
    http://mail-index.netbsd.org/tech-kern/2012/02/17/msg012728.html

Thanks to christos, manu, njoly, and jmmv for input.

Huge thanks to pgoyette for spinning these changes through some build
cycles and ATF.

sync to -current

sync to -current

sync to latest -current.

- Add __cacheline_aligned for nprocs, make fork_tfmrate static.
- Fix indentation, remove whitespaces and redundant brackets.

merge to -current.

Pull up following revision(s) (requested by rmind in ticket #1628):
	sys/kern/kern_fork.c: revision 1.184 via patch
fork1: fix stop-on-fork case, lend a correct lock to LWP for LSSTOP state.
Fixes PR/44935.

Pull up following revision(s) (requested by rmind in ticket #1628):
	sys/kern/kern_fork.c: revision 1.184 via patch
fork1: fix stop-on-fork case, lend a correct lock to LWP for LSSTOP state.
Fixes PR/44935.

Pull up following revision(s) (requested by rmind in ticket #1628):
	sys/kern/kern_fork.c: revision 1.184 via patch
fork1: fix stop-on-fork case, lend a correct lock to LWP for LSSTOP state.
Fixes PR/44935.

Disable PTRACE_FORK for vforked() children, because the parent is waiting
and will not receive the SIGTRAP in time.

Add support for PTRACE_FORK. NB: This does not (yet) work for vfork(), because:
1. When we vfork() PL_PPWAIT is set, and that makes us do regular disposition
   of the TRAP signal, and not indirect through the debugger.
2. The parent needs to keep running, so that the debugger can release it.
   Unfortunately, with vfork() we cannot release the parent because it will
   eventually core-dump since the parent and the child cannot run on the
   same address space.

don't use lwp_setprivate in fork, but copy the private lwp member directly
because userland might have messed with the TLS register without letting
the kernel know. This fixes fork() on amd64. Thanks chuq!

Pull up following revision(s) (requested by rmind in ticket #1629):
	sys/kern/kern_fork.c: revision 1.181
Inherit proc_t::p_mqueue_cnt on fork().

Pull up following revision(s) (requested by rmind in ticket #1629):
	sys/kern/kern_fork.c: revision 1.181
Inherit proc_t::p_mqueue_cnt on fork().

Pull up following revision(s) (requested by rmind in ticket #1629):
	sys/kern/kern_fork.c: revision 1.181
Inherit proc_t::p_mqueue_cnt on fork().

Sync with HEAD.

sync with head

fork1: fix stop-on-fork case, lend a correct lock to LWP for LSSTOP state.

Fixes PR/44935.

- Remove FORK_SHARELIMIT and PL_SHAREMOD, simplify lim_privatise().
- Use kmem(9) for struct plimit::pl_corename.

Pull in lwp_setprivate/cpu_lwp_setprivate from -current.
Also pull in lwp_getpcb

Remove IRIX emulation

- Move some checks into mqueue_get() and avoid some duplication.
- Simplify message queue descriptor unlinking and closure operations.
- Update proc_t::p_mqueue_cnt atomically.  Inherit it on fork().
- Use separate allocation for the name of message queue.

sync with head

Preserve l_private across forks.

sync with head

Copy PK_32 to p2->p_flag instead of doing it in the cpu_proc_fork hook.

Sync with HEAD.

sync with head.

many changes for COMPAT_LINUX:
 - update the linux syscall table for each platform.
 - support new-style (NPTL) linux pthreads on all platforms.
   clone() with CLONE_THREAD uses 1 process with many LWPs
   instead of separate processes.
 - move the contents of sys__lwp_setprivate() into a new
   lwp_setprivate() and use that everywhere.
 - update linux_release[] and linux32_release[] to "2.6.18".
 - adjust placement of emul fork/exec/exit hooks as needed
   and adjust other emul code to match.
 - convert all struct emul definitions to use named initializers.
 - change the pid allocator to allow multiple pids to refer to the same proc.
 - remove a few fields from struct proc that are no longer needed.
 - disable the non-functional "vdso" code in linux32/amd64,
   glibc works fine without it.
 - fix a race in the futex code where we could miss a wakeup after
   a requeue operation.
 - redo futex locking to be a little more efficient.

sync with head

increment p_nrlwps in lwp_create rather than letting callers do so
as it's always decremented by lwp_exit.  this fixes error recovery of
eg. aio_procinit.

Sync with HEAD.

sync with head

DTrace: Add an SDT (Statically Defined Tracing) provider framework, and
implement most of the proc provider.  Adds proc:::create, exec,
exec_success, exec_faillure, signal_send, signal_discard, signal_handle,
lwp_create, lwp_start, lwp_exit.

The VATTR_NULL/VREF/VHOLD/HOLDRELE() macros lost their will to live
years ago when the kernel was modified to not alter ABI based on
DIAGNOSTIC, and now just call the respective function interfaces
(in lowercase).  Plenty of mix'n match upper/lowercase has creeped
into the tree since then.  Nuke the macros and convert all callsites
to lowercase.

no functional change

Remove uarea swap-out functionality:

- Addresses the issue described in PR/38828.
- Some simplification in threading and sleepq subsystems.
- Eliminates pmap_collect() and, as a side note, allows pmap optimisations.
- Eliminates XS_CTL_DATA_ONSTACK in scsipi code.
- Avoids few scans on LWP list and thus potentially long holds of proc_lock.
- Cuts ~1.5k lines of code.  Reduces amd64 kernel size by ~4k.
- Removes __SWAP_BROKEN cases.

Tested on x86, mips, acorn32 (thanks <mpumford>) and partly tested on
acorn26 (thanks to <bjh21>).

Discussed on <tech-kern>, reviewed by <ad>.

Sync with HEAD.

Commit is split, to avoid a "too many arguments" protocol error.

sync with head.

Sync with HEAD.

use kauth instead of uid != 0

Sync with HEAD.

Sync with HEAD.

malloc -> kmem_alloc.

Sync with HEAD.

Move uidinfo to its own module in kern_uidinfo.c and include in rump.
No functional change to uidinfo.

Sync with HEAD.

Sync w/ -current. 34 merge conflicts to follow.

Sync with head.

sync with head.

- PPWAIT is need only be locked by proc_lock, so move it to proc::p_lflag.
- Remove a few needless lock acquires from exec/fork/exit.
- Sprinkle branch hints.

No functional change.

Sync with HEAD.

Also fix build.

sync with head

Most contention on proc_lock is from getppid(), so cache the parent's PID.

If vfork(), we want the LWP to run fast and on the same CPU
as its parent, so that it can reuse the VM context and cache
footprint on the local CPU.

Sync with HEAD.

Hold proc_lock when sleeping on p_waitcv, not proc::p_lock.

tsleep -> kpause

Start profiling clock on new process before setting it running, in case
there is a preemption.

Reduce ifdefs due to MULTIPROCESSOR slightly.

sync with head.

sync with head.

Per discussion with ad, remove most of the #include <sys/sa.h> lines
as they were including sa.h just for the type(s) needed for syscallargs.h.

Instead, create a new file, sys/satypes.h, which contains just the
types needed for syscallargs.h. Yes, there's only one now, but that
may change and it's probably more likely to change if it'd be difficult
to handle. :-)

Per discussion with matt at n dot o, add an include of satypes.h to
sigtypes.h. Upcall handlers are kinda signal handlers, and signalling
is the header file that's already included for syscallargs.h that
closest matches SA.

This shaves about 3000 lines off of the diff of the branch relative
to the base. That also represents about 18% of the total before this
checkin.

I think this reduction is very good thing.

Initial checkin of re-adding SA. Everything except kern_sa.c
compiles in GENERIC for i386. This is still a work-in-progress, but
this checkin covers most of the mechanical work (changing signalling
to be able to accomidate SA's process-wide signalling and re-adding
includes of sys/sa.h and savar.h). Subsequent changes will be much
more interesting.

Also, kern_sa.c has received partial cleanup. There's still more
to do, though.

Remove clause 3 and 4 from TNF licenses

Merge proc::p_mutex and proc::p_smutex into a single adaptive mutex, since
we no longer need to guard against access from hardware interrupt handlers.

Additionally, if cloning a process with CLONE_SIGHAND, arrange to have the
child process share the parent's lock so that signal state may be kept in
sync. Partially addresses PR kern/37437.

Network protocol interrupts can now block on locks, so merge the globals
proclist_mutex and proclist_lock into a single adaptive mutex (proc_lock).
Implications:

- Inspecting process state requires thread context, so signals can no longer
  be sent from a hardware interrupt handler. Signal activity must be
  deferred to a soft interrupt or kthread.

- As the proc state locking is simplified, it's now safe to take exit()
  and wait() out from under kernel_lock.

- The system spends less time at IPL_SCHED, and there is less lock activity.

Sync with HEAD.

sync with head.

sync with head.

Undo 1.150 (Don't make root an exception when enforcing rlimits). No other
Unix behaves this way and it breaks too many things, e.g. web servers.

sync with HEAD

Catch up with descriptor handling changes. See kern_descrip.c revision
1.173 for details.

sync with head.

Set p->p_trace_enabled in fork and whenever the controlling falgs change
instead of doing it in syscall_intern().
Note that syscall_intern() must still be called when the flags change
since many ports use a different copy of the syscall entry code when
tracing is enabled.

Sync with HEAD.

sync with head.

Authorize using the LWP cached credentials, not process credentials.

sync with head

sync with HEAD

Sync with HEAD

Make fork use kauth.

Been running in my tree for over a month at least.

Reviewed and okay yamt@, and special thanks to him as well as rittera@
for making this possible through fixing NDIS to not call fork1() with
l1 != curlwp.

Sync with HEAD

Merge vmlocking2 to head.

Remove systrace. Ok core@.

Sync with HEAD.

- Push kernel_lock back into exit, wait and sysctl system calls, mainly
  for visibility.
- Serialize calls to brk() from within the same process.
- Mark more syscalls MPSAFE.

Sync with head.

Convert all the system call entry points from:
    int foo(struct lwp *l, void *v, register_t *retval)
to:
    int foo(struct lwp *l, const struct foo_args *uap, register_t *retval)
Fixup compat code to not write into 'uap' and (in some cases) to actually
pass a correctly formatted 'uap' structure with the right name to the
next routine.
A few 'compat' routines that just call standard ones have been deleted.
All the 'compat' code compiles (along with the kernels required to test
build it).
98% done by automated scripts.

Sync with HEAD.

Sync with HEAD.

Sync with head.

sync with head

Match the docs: MUTEX_DRIVER/SPIN are now only for porting code written
for Solaris.

Use atomics to maintain nprocs.

Don't make root an exception when enforcing rlimits.

Suggested by yamt@ months ago; okay christos@.

Soft interrupts can now take proclist_lock, so there is no need to
double-lock alllwp or allproc.

Sync with HEAD. amd64 Xen support needs testing.

Tidy up the sigacts locking a bit: sigacts can be shared between
multiple processes.

Sync with HEAD.

sync with head.

Sync with HEAD

Sync with HEAD.

sync with -HEAD

Merge from vmlocking:

- pool_cache changes.
- Debugger/procfs locking fixes.
- Other minor changes.

sync with HEAD

Sync with HEAD.

Merge scheduler changes from the vmlocking branch. All discussed on
tech-kern:

- Invert priority space so that zero is the lowest priority. Rearrange
  number and type of priority levels into bands. Add new bands like
  'kernel real time'.
- Ignore the priority level passed to tsleep. Compute priority for
  sleep dynamically.
- For SCHED_4BSD, make priority adjustment per-LWP, not per-process.

- Fix interactivity problems under high load. Beacuse soft interrupts
  are being stacked on top of regular LWPs, more often than not aston()
  was being called on a soft interrupt thread instead of a user thread,
  meaning that preemption was not happening on EOI.

- Don't use bool in a couple of data structures. Sub-word writes are not
  always atomic and may clobber other fields in the containing word.

- For SCHED_4BSD, make p_estcpu per thread (l_estcpu). Rework how the
  dynamic priority level is calculated - it's much better behaved now.

- Kill the l_usrpri/l_priority split now that priorities are no longer
  directly assigned by tsleep(). There are three fields describing LWP
  priority:

        l_priority: Dynamic priority calculated by the scheduler.
                This does not change for kernel/realtime threads,
                and always stays within the correct band. Eg for
                timeshared LWPs it never moves out of the user
                priority range. This is basically what l_usrpri
                was before.

        l_inheritedprio: Lent to the LWP due to priority inheritance
                (turnstiles).

        l_kpriority: A boolean value set true the first time an LWP
                sleeps within the kernel. This indicates that the LWP
                should get a priority boost as compensation for blocking.
                lwp_eprio() now does the equivalent of sched_kpri() if
                the flag is set. The flag is cleared in userret().

- Keep track of scheduling class (OTHER, FIFO, RR) in struct lwp, and use
  this to make decisions in a few places where we previously tested for a
  kernel thread.

- Partially fix itimers and usr/sys/intr time accounting in the presence
  of software interrupts.

- Use kthread_create() to create idle LWPs. Move priority definitions
  from the various modules into sys/param.h.

- newlwp -> lwp_create

Sync with HEAD.

sync with head.

- Simplify debugger/procfs reference counting of processes. Use a per-proc
  rwlock: rw_tryenter(RW_READER) to gain a reference, and rw_enter(RW_WRITER)
  by the process itself to drain out reference holders before major changes
  like exiting.
- Fix numerous bugs and locking issues in procfs.
- Mark procfs MPSAFE.

Make ras_lookup() lockless.

Sync with head.

sync with head.

Sync with HEAD.

Change the way p->p_limit (and hence p->p_rlimit) is locked.
Should fix PR/36939 and make the rlimit code MP safe.
Posted for comment to tech-kern (non received!)

The p_limit field (for a process) is only be changed once (on the first
  write), and a reference to the old structure is kept (for code paths
  that have cached the pointer).
Only p->p_limit is now locked by p->p_mutex, and since the referenced memory
  will not go away, is only needed if the pointer is to be changed.
The contents of 'struct plimit' are all locked by pl_mutex, except that the
  code doesn't bother to acquire it for reads (which are basically atomic).
Add FORK_SHARELIMIT that causes fork1() to share the limits between parent
  and child, use it for the IRIX_PR_SULIMIT.
Fix borked test for both IRIX_PR_SUMASK and IRIX_PR_SDIR being set.

Rename members of 'struct plimit' so that the fields are 'pl_xxx' and
no longer have the same names as members of 'struct proc'.

sync with head.

Sync with HEAD.

Sync with HEAD.

Sync with HEAD.

Changes to make ktrace LKM friendly and reduce ifdef KTRACE. Proposed
on tech-kern.

Sync with head.

Sync with head.

Merge some of the less invasive changes from the vmlocking branch:

- kthread, callout, devsw API changes
- select()/poll() improvements
- miscellaneous MT safety improvements

splstatclock, spllock -> splhigh

Sync with head.

merge yamt-idlelwp branch.  asked by core@.  some ports still needs work.

from doc/BRANCHES:

	idle lwp, and some changes depending on it.

	1. separate context switching and thread scheduling.
	   (cf. gmcgarry_ctxsw)
	2. implement idle lwp.
	3. clean up related MD/MI interfaces.
	4. make scheduler(s) modular.

sync with head.

Import of POSIX Asynchronous I/O.
Seems to be quite stable. Some work still left to do.

Please note, that syscalls are not yet MP-safe, because
of the file and vnode subsystems.

Reviewed by: <tech-kern>, <ad>

proc_trampoline_mp: don't grab kernel_lock for LWPs marked as MP safe.

- Make context switch counters 64-bit, and count the total number of
  context switches + voluntary, instead of involuntary + voluntary.
- Add lwp::l_swaplock for uvm.
- PHOLD/PRELE are replaced.

- Ensure that context switch always happens at least at IPL_SCHED, even
  if no spin lock is held. Should fix the assertion failure seen on hppa.
- Reduce the amount of spl frobbing in mi_switch.
- Add some comments.

Reviewed by yamt@.

sync with head.

- Put a lock around the proc's CWD info (work in progress).
- Replace some more simplelocks.
- Make lbolt a condvar.

Do not do an implicit enqueue in sched_switch(), move enqueueing back to
the dispatcher. Rename sched_switch() back to sched_nextlwp(). Add for
sched_enqueue() new argument, which indicates the calling from mi_switch().

Requested by yamt@

Sync with head.

Sync with kern_proc.c: make p2->p_rasmutex a spin mutex at IPL_SCHED.

Sync with HEAD.

- Make the proclist_lock a mutex. The write:read ratio is unfavourable,
  and mutexes are cheaper use than RW locks.
- LOCK_ASSERT -> KASSERT in some places.
- Hold proclist_lock/kernel_lock longer in a couple of places.

Kill caddr_t; there will be some MI fallout, but it will be fixed shortly.

- sync with head.
- move sched_changepri back to kern_synch.c as it doesn't know PPQ anymore.

sync with head.

TRUE -> true, FALSE -> false

Pick up some additional files that were missed before due to conflicts
with newlock2 merge:

Replace the Mach-derived boolean_t type with the C99 bool type.  A
future commit will replace use of TRUE and FALSE with true and false.

General Common Scheduler Framework (CSF) patch import. Huge thanks for
Daniel Sieger <dsieger at TechFak.Uni-Bielefeld de> for this work.

Short abstract: Split the dispatcher from the scheduler in order to
make the scheduler more modular. Introduce initial API for other
schedulers' implementations.

Discussed in tech-kern@
OK: yamt@, ad@

Note: further work will go soon.

Change the process/lwp flags seen by userland via sysctl back to the
P_*/L_* naming convention, and rename the in-kernel flags to avoid
conflict. (P_ -> PK_, L_ -> LW_ ). Add back the (now unused) LSDEAD
constant.

Restores source compatibility with pre-newlock2 tools like ps or top.

Reviewed by Andrew Doran.

- separate context switching and thread scheduling.
- introduce idle lwp.
- change some related MD/MI interfaces and implement i386 version.

Restore proc::p_userret in a limited way for Linux compat. XXX

Merge newlock2 to head.

IPL_STATCLOCK needs to be >= IPL_CLOCK, so assume that proc::p_stmutex is
always a spinlock.

- When clearing signals dequeue siginfo first and free later, once
  outside the lock permiter.
- Push kernel_lock back in a a couple of places.
- Adjust limcopy() to be MP safe (this needs redoing).
- Fix a couple of bugs noticed along the way.
- Catch up with condvar changes.

Sync with head.

Remove support for SA. Ok core@.

Drop proclist_mutex and proc::p_smutex back to IPL_VM.

Introduce kauth_proc_fork() to control credential inheritance.

sync with head.

Checkpoint work in progress.

sync with head.

Checkpoint work in progress.

remove some __unused from function parameters.

- Redo LWP locking slightly and fix some races.
- Fix some locking botches.
- Make signal mask / stack per-proc for SA processes.
- Add _lwp_kill().

sync with head

Checkpoint work in progress on locking and per-LWP signals. Very much a
a work in progress and there is still a lot to do.

- sprinkle __unused on function decls.
- fix a couple of unused bugs
- no more -Wno-unused for i386

- Convert some lockmgr() locks to mutexes and RW locks.
- Acquire proclist_lock and p_crmutex in some obvious places.

sync with head

sync with head

- Always make p->p_cred a private copy before modifying.
- Share credentials among processes when forking.

sync with head.

sync with head.

Sync with head.

merge FreeBSD timecounters from branch simonb-timecounters
- struct timeval time is gone
  time.tv_sec -> time_second
- struct timeval mono_time is gone
  mono_time.tv_sec -> time_uptime
- access to time via
	{get,}{micro,nano,bin}time()
	get* versions are fast but less precise
- support NTP nanokernel implementation (NTP API 4)
- further reading:
  Timecounter Paper: http://phk.freebsd.dk/pubs/timecounter.pdf
  NTP Nanokernel: http://www.eecis.udel.edu/~mills/ntp/html/kern.html

Sync with head.

Merge 2006-05-24 NetBSD-current into the "peter-altq" branch.

sync with head.

integrate kauth.

- Move kauth_cred_t declaration to <sys/types.h>
- Cleanup struct ucred; forward declarations that are unused.
- Don't include <sys/kauth.h> in any header, but include it in the c files
  that need it.

Approved by core.

Adapt to kernel authorization KPI.

Adapt for timecounters: mostly use get*time() and use "time_second"
instead of "time.tv_sec".

merge ktrace-lwp.

Sync with HEAD. Here we go again...

Revert pullup ticket #316, because it breaks kernel compiles. A more
complete pullup request is forthcoming.
(requested by cube in ticket #341)

Pull up revision 1.122 (requested by cube in ticket #316):
Add P_CLDSIGIGN, P_NOCLDSTOP and P_NOCLDWAIT to the list of flags we want
to inherit from the parent process.

Add P_CLDSIGIGN, P_NOCLDSTOP and P_NOCLDWAIT to the list of flags we want
to inherit from the parent process.

sync with -current

sync with head.  xen and whitespace.  xen part is not finished.

Sync with HEAD.

Hi Perry!

Copyright maintenance.

nuke trailing whitespace

Fix the sync with head I botched.

Sync with HEAD.

- proc_alloc() already initializes p_stat to SIDL.
- copy unconditionaly inherited p_flag bits in a single place.

Pull up revision 1.117 (requested by jdolecek in ticket #762):
pass the fork flags down the emulation proc fork hook

Sync with HEAD.

Pullup rev 1.116 (requested by atatat in ticket #744)

When stopfork is set, we need to set p_nrlwps, since we are not going to
be running. PR#26468

Pullup rev 1.118 (requested by jdolecek in ticket #741)

Linux enforces CLONE_VM if CLONE_SIGHAND in clone(2) is specified,
follow the suit - this is intended to be Linux-compatible call.

Linux enforces CLONE_VM if CLONE_SIGHAND in clone(2) is specified,
follow the suit - this is intended to be Linux-compatible call

pass the fork flags down the emulation proc fork hook

PR/26468: Andrew Brown: Setting stopfork can panic the kernel.
When stopfork is set, we need to set p_nrlwps, since we are not going to
ber running.

Sync with HEAD

Provide a mutex for the process limits data structure.

Also defer the writing of KTR_EMUL entry.  Otherwise, the parent process
may sleep with setting KTRFAC_ACTIVE of child process and the child will
run without emitting any ktrace entry.

- Count number of zombies and stopped children and requeue them at the top
  of the sibling list so that find_stopped_child can be optimised to avoid
  traversing the entire sibling list - helps when a process has a lot of
  children.
- Modify locking in pfind() and pgfind() to that the caller can rely on the
  result being valid, allow caller to request that zombies be findable.
- Rename pfind() to p_find() to ensure we break binary compatibility.
- Remove svr4_pfind since p_find willnow do the job.
- Modify some of the SMP locking of the proc lists - signals are still stuffed.

Welcome to 1.6ZF

Remove p_nras from struct proc - use LIST_EMPTY(&p->p_raslist) instead.
Remove p_raslock and rename p_lwplock p_lock (one lock is enough).
Simplify window test when adding a ras and correct test on VM_MAXUSER_ADDRESS.
Avoid unpredictable branch in i386 locore.S
(pad fields left in struct proc to avoid kernel bump)

add siginfo lock and siginfo queue initialization.

Move UCB-licensed code from 4-clause to 3-clause licence.

Patches provided by Joel Baker in PR 22364, verified by myself.

Apply the aborted ktrace-lwp changes to a specific branch.  This is just for
others to review, I'm concerned that patch fuziness may have resulted in some
errant code being generated but I'll look at that later by comparing the diff
from the base to the branch with the file I attempt to apply to it.  This will,
at the very least, put the changes in a better context for others to review
them and attempt to tinker with removing passing of 'struct lwp' through
the kernel.

Back out the lwp/ktrace changes. They contained a lot of colateral damage,
and need to be examined and discussed more.

Pass lwp pointers throughtout the kernel, as required, so that the lwpid can
be inserted into ktrace records.  The general change has been to replace
"struct proc *" with "struct lwp *" in various function prototypes, pass
the lwp through and use l_proc to get the process pointer when needed.

Bump the kernel rev up to 1.6V

Alternative pid/proc allocater, removes all searches associated with pid
lookup and allocation, and any dependency on NPROC or MAXUSERS.
NO_PID changed to -1 (and renamed NO_PGID) to remove artificial limit
on PID_MAX.
As discussed on tech-kern.

Add "fork hooks", a'la "exec hooks" and "exit hooks" which allow
subsystems to do special processing to the parent and/or child at
fork time.

Merge the nathanw_sa branch.

Sync with HEAD.

Merge pcred and ucred, and poolify.  TBD: check backward compatibility
and factor-out some higher-level functionality.

Add an "inmem" argument to newlwp(), and use it to properly set
up L_INMEM in the new LWP.  Should fix a problem mentioned to me
by Nick Hudson.

replace magic number '500' in pid allocation code with a macro PID_SKIP,
defined in <sys/proc.h> (along PID_MAX, NO_PID)

put back portion of fork-bomb protection removed in last commit,
and make the sleep length depend on value of variable forkfsleep;
it's set to zero by default (no sleep)
this is a preparation for making the sleep length settable via sysctl

Sync with HEAD.

Sync with HEAD.

Remove portion of fork-bomb protection that has unfortunate side effects.

Couple fork-bomb defense changes:

- leave 5 processes for root-only use, the previous value of 1
  was unsufficient to execute additional commands once logged, and
  perhaps also not enough to actually login remotely with recent (open)sshd
- protect the log of "proc: table full" with ratecheck(), so that
  the message is only logged once per 10 seconds; though syslogd normally
  doesn't pass the repeated messages through, this avoids flooding
  syslogd and potentially also screen/logs
- If the process hits either system limit of number of processes in system,
  or user's limit of same, force the process to sleep for 0.5 seconds
  before returning failure. This turns 2000 rampaging fork monsters into
  2000 harmlessly snoozing fork monsters.
  The sleep is intentionally uninterruptible by signals.

These are not intended as ultimate protection agains fork-bombs.
Determined attacker can eat CPU differently than via repeating
fork() calls. But this is good enough to help protect against
programming mistakes or simple-minded tests.

Based on FreeBSD kern_fork.c change in revision 1.132 by
Mike Silbersack <silby at FreeBSD org>

Change also discussed on tech-kern@NetBSD.org, thread
'Fork bomb protection patch'.

cosmetic fix

change uvm_uarea_alloc() to indicate whether the returned uarea is already
backed by physical pages (ie. because it reused a previously-freed one),
so that we can skip a bunch of useless work in that case.
this fixes the underlying problem behind PR 18543, and also speeds up fork()
quite a bit (eg. 7% on my pc, 1% on my ultra2) when we get a cache hit.

fix systrace panic that was introduced when postponing pid number allocation
approved itojun

Reapply a fix lost in the catch up to -current.

Catch up to -current

Added two sysctl-able flags: proc.curproc.stopfork and proc.curproc.stopexec
that can be used to block a process after fork(2) or exec(2) calls. The
new process is created in the SSTOP state and is never scheduled for running.

This feature is designed so that it is esay to attach the process using gdb
before it has done anything.

It works also with sproc, kthread_create, clone...

merge kqueue branch into -current

kqueue provides a stateful and efficient event notification framework
currently supported events include socket, file, directory, fifo,
pipe, tty and device changes, and monitoring of processes and signals

kqueue is supported by all writable filesystems in NetBSD tree
(with exception of Coda) and all device drivers supporting poll(2)

based on work done by Jonathan Lemon for FreeBSD
initial NetBSD port done by Luke Mewburn and Jason Thorpe

Move pid allocation to the bottom of the process allocation, so that we
don't have to deal with partially initialized proc structs in the scheduler.
Pointed out by: Artur Grabowski and Chuck Silvers.

Catch up to -current.

sync kqueue with -current; this includes merge of gehenna-devsw branch,
merge of i386 MP branch, and part of autoconf rototil work

Don't include <sys/map.h>.

encapsulate knowledge of uarea allocation in some new functions.

Catch up to -current.

sync kqueue branch with HEAD

catch up with -current.

MI kernel support for user-level Restartable Atomic Sequences (RAS).

Catch up to -current.

Add FORK_CLEANFILES flag to fork1(), which makes the new process start out
with a clean descriptor set (ie. not copied or shared from parent).

for rfork()

Catch up to -current.

Whitespace.

catch up with -current.

No longer need to pull in lwp.h; proc.h pulls it in for us.

Add FORK_NOWAIT flag, which sets init as the parent of the forked
process. Useful for FreeBSD rfork() emulation.

ok'd by Christos

Curproc->curlwp renaming.

Change uses of "curproc->l_proc" back to "curproc", which is more like the
original use. Bare uses of "curproc" are now "curlwp".

"curproc" is now #defined in proc.h as ((curlwp) ? (curlwp)->l_proc) : NULL)
so that it is always safe to reference curproc (*de*referencing curproc
is another story, but that's always been true).

Oops, added one line too many when PID selection was rearranged.

catch up with -current.

Catch up to -current.

Niels Provos systrace work, ported to NetBSD by kittenz and reworked...

#include <sys/sa.h> before <sys/syscallargs.h>, to provide sa_upcall_t
now that <sys/param.h> doesn't include <sys/sa.h>.

(Behold the Power of Ed)

Use a pool cache for turnstiles, saving the memset (missed this in
previous commit).

First cut implementation of turnstiles, a specialized sleep queue used for
kernel synchronization objects.  A detailed description of turnstiles
can be found in:

	Solaris Internals: Core Kernel Architecture, by Jim Mauro
	   and Richard McDougall, section 3.7.

Note this implementation does not yet implement priority inheritence,
nor does it currently differentiate between reader and writer queues
(though they are provided for in the API).

Sync kqueue branch with -current.

Catch up to -current.

Make the coredump routine exec-format/emulation specific.  Split
out traditional NetBSD coredump routines into core_netbsd.c and
netbsd32_core.c (for COMPAT_NETBSD32).

Implement POSIX realtime timers, and reimplement getitimer() and setitimer()
in terms of them.

Catch up to -current.

Sync the thorpej-mips-cache branch with -current.

add RCSIDs

Call uvm_proc_fork() before newlwp() to fork the process's VM space, if
necessary.  This ensures that p2 is more-fully initialized before entering
newlwp().  This also ensures cpu_fork() will have access to p_vmspace for
both processes.

KERNEL_PROC_LOCK/KERNEL_PROC_UNLOCK take struct lwp *, not struct proc *.

Catch up with -current.

add calls to KNOTE(9) as appropriate

flags was used uninitialized.

Linux-compatible clone(2) system call, lifted from the Linux
compatibility module.  Based on patches from Bang Jun-Young <bjy@mogua.org>.