CVS log for src/sys/arch/news68k/news68k/trap.c

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Default branch: MAIN

Largely unify the <machine/cpu.h> headers on the m68k platforms.

Arrange to update cached LWP credentials in userret() rather than during
syscall/trap entry, eliminating a test+branch on every syscall/trap.

This wasn't possible in the 3.99.x timeframe when l->l_cred came about
because there wasn't a reliable/timely way to force an ONPROC LWP running on
a remote CPU into the kernel (which is just about the only new thing in
this scheme).

Improve KGDB enabled build for news68k:
* include sys/kgdb.h in news68k/trap.c for missing definitions.
* cast second kgdb_trap argument to (db_regs_t *).
* build m68k/kgdb_machdep.c for kgdb_trap() implementation.

Same as for mvme68k, build complains about undefined reference to zs_check_kgdb
due to missing port specific zs kgdb implementation for MI zs(4) driver though.

Remove ancient /*ARGSUSED*/ comments.

Call cnpollc(9) before cngetc(9) as the cons(9) man page says.

Affects only inside #ifdef DEBUG part on "trap during panic" in trap.c
derived from hp300.

Merge changes from current as of 20200406

mi_userret(): take care of calling preempt(), set spc_curpriority directly,
and remove MD code that does the same.

Sync with HEAD

Overhaul the API used to fetch and store individual memory cells in
userspace.  The old fetch(9) and store(9) APIs (fubyte(), fuword(),
subyte(), suword(), etc.) are retired and replaced with new ufetch(9)
and ustore(9) APIs that can return proper error codes, etc. and are
implemented consistently across all platforms.  The interrupt-safe
variants are no longer supported (and several of the existing attempts
at fuswintr(), etc. were buggy and not actually interrupt-safe).

Also augmement the ucas(9) API, making it consistently available on
all plaforms, supporting uniprocessor and multiprocessor systems, even
those that do not have CAS or LL/SC primitives.

Welcome to NetBSD 8.99.37.

Refactor the 68040 writeback() from each m68k port's trap handler into a
shared copy: m68040_writeback().  It is essentially a copy of the Atari
version, with some minor cosmetic tweaks and one small performance optimization
from the mvme68k port.

Tested by rjs@ on a Quadra 950.  (Thanks!)

update from HEAD

Sync with HEAD

Handle EINVAL in the fault path and send SIGBUS on mmap'd access past EOF

sync with head

sync to -current.

Remove COMPAT_SA / KERN_SA.  Welcome to 6.99.3!
Approved by core@.

Sync with HEAD.

sync with head

Sync with HEAD

Remove clause 3 (UCB advertising clause) from the University of Utah
copyright.  Confirmed by Mike Hibler, mike at cs.utah.edu - thanks!
Also, merge UCB and Utah copyright texts back into one, as they
originally were.

Extra verification by snj@.

Explicitly include <machine/pcb.h> for struct pcb.

Move counting of faults, traps, intrs, soft[intr]s, syscalls, and nswtch
from uvmexp to per-cpu cpu_data and move them to 64bits.  Remove unneeded
includes of <uvm/uvm_extern.h> and/or <uvm/uvm.h>.

Sync with HEAD.

sync with head.

implement ucas_* for m68k.

sync with head

fix PR 6724 - convert m68k options to defflag's.  this means that
M680[12346] are now available from opt_m68k_arch.h.  FPSP meantioned
in the PR has already been fixed, and i could not find any more.

i built these kernels to ensure i did not break their builds:

amiga: GENERIC DRACO
atari: HADES FALCON MILAN-PCIIDE
mac68k: GENERIC
sun2: GENERIC
sun3: GENERIC GENERIC3X
cesfic: attempted GENERIC, does not build due to lack of machine/bus.h
hp300: GENERIC
luna68k: GENERIC
mvme68k: GENERIC
news68k: GENERIC
next68k: GENERIC
x68k: GENERIC

sync with head

Sync with HEAD.

fix copy{in,out}{,str}() to return the error returned by uvm_fault().
fixes PR 41813.

sync with head

Use lwp_getpcb() on m68k ports, clean from struct user usage.

sync with head.

Sync with HEAD.

Pull up following revision(s) (requested by martin in ticket #332):
	sys/arch/amiga/amiga/trap.c: revision 1.122
	sys/arch/atari/atari/trap.c: revision 1.99
	sys/arch/cesfic/cesfic/trap.c: revision 1.43
	sys/arch/hp300/hp300/trap.c: revision 1.140
	sys/arch/luna68k/luna68k/trap.c: revision 1.55
	sys/arch/m68k/include/signal.h: revision 1.25
	sys/arch/m68k/m68k/sig_machdep.c: revision 1.41
	sys/arch/mac68k/mac68k/trap.c: revision 1.136 via patch
	sys/arch/mvme68k/mvme68k/trap.c: revision 1.98
	sys/arch/news68k/news68k/trap.c: revision 1.60
	sys/arch/next68k/next68k/trap.c: revision 1.75
	sys/arch/sun2/sun2/trap.c: revision 1.37
	sys/arch/sun3/sun3/trap.c: revision 1.136
	sys/arch/x68k/x68k/trap.c: revision 1.97
Centralize fpu exception to siginfo code encoding for all m68k archs,
fixes a failure in the lib/libc/ieeefp/except regression test.

Centralize fpu exception to siginfo code encoding for all m68k archs,
fixes a failure in the lib/libc/ieeefp/except regression test.

Sync with HEAD.

Sync with HEAD.

Merge wrstuden-revivesa into HEAD.

Change how we make SA threads not generate upcalls. Instead of clearing
LW_SA, use a private flag, LP_SA_NOBLOCK, that we set when we want
to not generate upcalls. This means we do NOT need to lock (l)
(ourselves) to set it.

Adjust tests that look at LW_SA. Now, we are an upcall-generating
lwp if ((l->l_flag & LW_SA) && (~l->l_pflag & LP_SA_NOBLOCK)).

Introduce code pattern to set & remember this:

	f = ~l->l_pflag & LP_SA_NOBLOCK;
	l->l_pflag |= LP_SA_NOBLOCK;

	...

	/* f is now LP_SA_NOBLOCK if it wasn't set in l_pflag before */

	l->l_pflag ^= f;

I updated a lot of the trap handlers to do trap handling iff LP_SA_NOBLOCK
is not set. I tried to figure out if the trap handler could be triggered
for user-based faults as opposed to kernel faults to user addresses, and
only look at LP_SA_NOBLOCK for the latter.

Above is a result of discussions with rmind at to reduce lock twiddling.

Also, per same discussions, add locking to sys_sa_preempt(). p_lock is
the lock we want.

Also, per same discussions, remove use of LSSUSPENDED as a thread state.
We needed to use it when we were emulating the 4.X and previous behavior
of hiding cached threads. For the moment, we now have them instead
remain visible to all and have them sleeping on the "lwpcache" wait
channel.

sa_newcachelwp(): sa_putcachelwp() wants savp_mutex held, not p_lock.

Tweak some comments.

Re-add cpu_upcall() and page fault code. i386 kernels now compile.
They don't boot, but that seems to be a consequence of current from the
day this branch was started.

Sync with HEAD.

sync with head.

Per discussion with ad at n dot o, revert signal mask handling
changes.

The l_sigstk changes are most likely totally un-needed as SA will
never use a signal stack - we send an upcall (or will as other
diffs are brought in).

The l_sigmask changes were too controvertial. In all honesty, I
think it's probably best to revert them. The main reason they were
there is the fact that in an SA process, we don't mask signals per
kernel thread, we mask them per user thread. In the kernel, we want
them all to get turned into upcalls. Thus the normal state of
l_sigmask in an SA process is for it to always be empty.

While we are in the process of delivering a signal, we want to
temporarily mask a signal (so we don't recursively exhaust our
upcall stacks). However signal delivery is rare (important, but
rare), and delivering back-to-back signals is even rarer. So rather
than cause every user of a signal mask to be prepared for this very
rare case, we will just add a second check later in the signal
delivery code. Said change is not in this diff.

This also un-compensates all of our compatability code for dealing
with SA. SA is a NetBSD-specific thing, so there's no need for
Irix, Linux, Solaris, SVR4 and so on to cope with it.

As previously, everything other than kern_sa.c compiles in i386
GENERIC as of this checkin. I will switch to ALL soon for compile
testing.

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.

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.

Sync with HEAD.

sync with head

sync with HEAD

Sync with HEAD

Remove COMPAT_HPUX.

Sync with HEAD.

sync with head.

Sync with HEAD

sync with HEAD

Sync with HEAD.

Don't set l_usrpri / spc_curpriority here. mi_userret() does it.

Merge the ppcoea-renovation branch to HEAD.

This branch was a major cleanup and rototill of many of the various OEA
cpu based PPC ports that focused on sharing as much code as possible
between the various ports to eliminate near-identical copies of files in
every tree.  Additionally there is a new PIC system that unifies the
interface to interrupt code for all different OEA ppc arches.  The work
for this branch was done by a variety of people, too long to list here.

TODO:
bebox still needs work to complete the transition to -renovation.
ofppc still needs a bunch of work, which I will be looking at.
ev64260 still needs to be renovated
amigappc was not attempted.

NOTES:
pmppc was removed as an arch, and moved to a evbppc target.

Sync with head.

Sync with HEAD

Sync with somewhat-recent netbsd-4.

Pull up following revision(s) (requested by mhitch in ticket #866):
	sys/arch/atari/atari/trap.c:		1.92
	sys/arch/mac68k/mac68k/trap.c:		1.129
	sys/arch/amiga/amiga/trap.c:		1.116
	sys/arch/mvme68k/mvme68k/trap.c:	1.91
	sys/arch/news68k/news68k/trap.c:	1.54
	sys/arch/sun3/sun3/trap.c:		1.131
	sys/arch/next68k/next68k/trap.c:	1.68
	sys/arch/luna68k/luna68k/trap.c:	1.47
	sys/arch/cesfic/cesfic/trap.c:		1.36
	sys/arch/x68k/x68k/trap.c:		1.90
	sys/arch/hp300/hp300/trap.c:		1.132
68030 and 68040 processors consider the read portion of a read-modify-write
transfer as a write to ensure the memory is writable before starting any
transfer.  The fault status information does not reflect this in the 'read'
status bit (i.e. it shows up as a read access), so faults with a RMW access
to non-writable memory was not getting the correct protection.  The page would
be read-only and the instruction would fault over and over.
A specific example is when a process forks, and the child process attempts
to execute a RMW access to a data page, which is read-only because it's CoP
Copy-On-Write.
When checking if the page needs to be writablek, also check the locked transfer
and treat any locked transfer as a write.
68060 already handled this correctly, since it has separate read and write
fault bits, and both are set on a RMW access and the trap code was checking
the write status bit.
Fixes PR#36848.

Sync with HEAD.

sync with head.

Sync with HEAD.

Sync w/ NetBSD-4-RC_1

68030 and 68040 processors consider the read portion of a read-modify-write
transfer as a write to ensure the memory is writable before starting any
transfer.  The fault status information does not reflect this in the 'read'
status bit (i.e. it shows up as a read access), so faults with a RMW access
to non-writable memory was not getting the correct protection.  The page would
be read-only and the instruction would fault over and over.

A specific example is when a process forks, and the child process attempts
to execute a RMW access to a data page, which is read-only because it's CoP
Copy-On-Write.

When checking if the page needs to be writablek, also check the locked transfer
and treat any locked transfer as a write.

68060 already handled this correctly, since it has separate read and write
fault bits, and both are set on a RMW access and the trap code was checking
the write status bit.

Fixes PR#36848.

Sync with head.

Sync with head.

Sync with HEAD.

Pull up following revision(s) (requested by mhitch in ticket #728):
	sys/arch/mvme68k/mvme68k/locore.s: revision 1.98
	sys/arch/mac68k/mac68k/trap.c: revision 1.128
	sys/arch/next68k/next68k/locore.s: revision 1.48
	sys/arch/mac68k/mac68k/locore.s: revision 1.152
	sys/arch/sun3/sun3/locore.s: revision 1.88
	sys/arch/sun2/sun2/locore.s: revision 1.19
	sys/arch/sun2/sun2/trap.c: revision 1.32
	sys/arch/m68k/m68k/db_trace.c: revision 1.51
	sys/arch/mvme68k/mvme68k/trap.c: revision 1.90
	sys/arch/news68k/news68k/trap.c: revision 1.53
	sys/arch/luna68k/luna68k/locore.s: revision 1.27
	sys/arch/atari/atari/locore.s: revision 1.99
	sys/arch/sun3/sun3/trap.c: revision 1.130
	sys/arch/x68k/x68k/trap.c: revision 1.89
	sys/arch/next68k/next68k/trap.c: revision 1.67
	sys/arch/x68k/x68k/locore.s: revision 1.79
	sys/arch/news68k/news68k/locore.s: revision 1.43
	sys/arch/luna68k/luna68k/trap.c: revision 1.46
	sys/arch/hp300/hp300/locore.s: revision 1.140
	sys/arch/cesfic/cesfic/locore.s: revision 1.15
	sys/arch/cesfic/cesfic/trap.c: revision 1.35
	sys/arch/m68k/m68k/trap_subr.s: revision 1.12
	sys/arch/amiga/amiga/locore.s: revision 1.143
Pass a frame pointer to trap() rather than the 'entire frame' trick.  Gcc4
was optimizing away modifications to the frame contents (it's not nice to
trick gcc).  Pass the pointer as the first argument to reduce the number
of places that would be changed otherwise.  Fixes the getcwd regression
test on most m68k ports.

Pass a frame pointer to trap() rather than the 'entire frame' trick.  Gcc4
was optimizing away modifications to the frame contents (it's not nice to
trick gcc).  Pass the pointer as the first argument to reduce the number
of places that would be changed otherwise.  Fixes the getcwd regression
test on most m68k ports.

Sync with head.

Update to HEAD.

Adapt news68k to yamt-idlelwp. Tested on NWS-1750.

Sync with HEAD.

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

TRUE -> true, FALSE -> false

sync with head.

Apply some changes for newlock2, taken from other m68k ports.

Merge newlock2 to head.

Remove support for SA. Ok core@.

sync with head.

sync with head

sync with head

Use the LWP cached credentials where sane.

- Hold a reference to the process credentials in each struct lwp.
- Update the reference on syscall and user trap if p_cred has changed.
- Collect accounting flags in the LWP, and collate on LWP exit.

sync with head.

Sync with head.

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

sync with head.

include kauth.h for kauth_cred_geteuid.

integrate kauth.

Sync with head.

sync with head - hopefully this will work

sync with head.

Merge 2006-03-28 NetBSD-current into the "peter-altq" branch.

Reduce diff against hp300/trap.c.

adapt to uvm_fault() interface cleanup: kill the useless 3rd argument

Adapt to kernel authorization KPI.

I expect *some* lossage here...

sync with head.

Fix some typos.

merge ktrace-lwp.

Sync with HEAD. Here we go again...

Add a const.

Fix the sync with head I botched.

Sync with HEAD.

- Use ANSI function declarations and make some functions static.
- Some KNF

Sync with HEAD

use uvm_grow() to update stack segment size on stack page fault instead
of MD code

Sync with HEAD

add kernel part of concurrency support for SA on MP systems
- move per VP data into struct sadata_vp referenced from l->l_savp
  * VP id
  * lock on VP data
  * LWP on VP
  * recently blocked LWP on VP
  * queue of LWPs woken which ran on this VP before sleep
  * faultaddr
  * LWP cache for upcalls
  * upcall queue
- add current concurrency and requested concurrency variables
- make process exit run LWP on all VPs
- make signal delivery consider all VPs
- make timer events consider all VPs
- add sa_newsavp to allocate new sadata_vp structure
- add sa_increaseconcurrency to prepare new VP
- make sys_sa_setconcurrency request new VP or wakeup idle VP
- make sa_yield lower current concurrency
- set sa_cpu = VP id in upcalls
- maintain cached LWPs per VP

Remove obsolete comments about curproc.

Extend the #ifdef M68040 so that the `sig' variable declaration is moved
in as well, as it's otherwise not used. (from atari/atari/trap.c and
x68k/x68k/trap.c)

Reduce code duplication by adding mi_userret() in sys/userret.h
containing signal posting, kernel-exit handling and sa_upcall processing.

XXX the pc532, sparc, sparc64 and vax ports should have their
XXX userret() code rearranged to use this.

* Shuffle some data structures so, and add a flags word to ksiginfo_t.
  Right now the only flag is used to indicate if a ksiginfo_t is a
  result of a trap.  Add a predicate macro to test for this flag.
* Add initialization macros for ksiginfo_t's.
* Add accssor macro for ksi_trap.  Expands to 0 if the ksiginfo_t was
  not the result of a trap.  This matches the sigcontext trapcode semantics.
* In kpsendsig(), use KSI_TRAP_P() to select the lwp that gets the signal.
  Inspired by Matthias Drochner's fix to kpsendsig(), but correctly handles
  the case of non-trap-generated signals that have a > 0 si_code.

This patch fixes a signal delivery problem with threaded programs noted by
Matthias Drochner on tech-kern.

As discussed on tech-kern.  Reviewed and OK's by Christos.

SA_SIGINFO support for m68k (port specific changes)

add MD part of SA/pthread pagefault handling on all m68k ports

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

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

__KERNEL_RCSID()

Use PAGE_SIZE rather than NBPG.

success, not sucess. Noted by mjl.

Merge the nathanw_sa branch.

Sync with HEAD.

Fix -Wsign-compare warnings.

In the SA universe, the switch-to-this-LWP decision is made at a
different level than where preempt() calls are made, which renders
the "newlwp" argument useless.  Replace it with a "more work to do"
boolean argument.  Returning to userspace preempt() calls pass 0.
"Voluntary" preemptions in e.g. uiomove() pass 1.  This will be used
to indicate to the SA subsystem that the LWP is not yet finished in
the kernel.

Collapse the SA vs. non-SA cases of preempt() together, making the
conditional code block much smaller, and don't call sa_preempt() if
more work is to come.

NOTE: THIS IS NOT A COMPLETE FIX TO THE preempt()-in-uiomove() PROBLEM
THAT CURRENTLY EXISTS FOR SA PROCESSES.

Sync with HEAD.

Remove __P().

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

Catch up to -current

finish conversion to the common m68k cacheops:
add support for machine-specific flavors of the ops for off-chip caches.
many thanks to Izumi Tsutsui for his help with this.

merge the 12 copies of vm_machdep.c on the m68k platforms.
clean up some other stuff along the way, including:
 - use m68k/cacheops.*, remove duplicates from cpu.h.
 - centralize a few declarations in (all the copies of) cpu.h.
 - define M68K_VAC on platforms which have a VAC.
 - switch the sun platforms to the (now common) proc_trampoline().
 - do the phys_map thang on the sun platforms too, no reason not to.

Change "if (l->l_flag & L_SA_UPCALL)" to "while (l->l_flag & L_SA_UPCALL)"
in userret() functions or equivalent, to permit delivery of multiple upcalls
in a single kernel entry.

XXX It's getting crowded in here. Collapsing posting signals, upcalls, and
XXX kernel-exit handling into one mechanism would be nice.

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

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).

Catch up with -current.

Catch up to -current.

allow writing to write-only mappings.  fixes PR 3493.

cpu_upcall() -> sa_upcall_userret().

Deal with `want_resched' with trap()'s T_ASTFLT case where it belongs
instead of in userret().

MD Scheduler Activation bits for News68k.
Compile-tested only.

Catch up with -current.

Update the kqueue branch to HEAD.

file trap.c was added on branch nathanw_sa on 2001-11-18 18:42:20 +0000

Update pmap_update to now take the updated pmap as an argument.
This will allow improvements to the pmaps so that they can more easily defer expensive operations, eg tlb/cache flush, til the last possible moment.

Currently this is a no-op on most platforms, so they should see no difference.

Reviewed by Jason.

bcopy() -> memcpy() (I guess there is no overlap here)

Catch up to -current.

replace vm_map{,_entry}_t with struct vm_map{,_entry} *.

add missing   #include "opt_kgdb.h"

Sprinkle pmap_update() calls after calls to:
- pmap_enter()
- pmap_remove()
- pmap_protect()
- pmap_kenter_pa()
- pmap_kremove()
as described in pmap(9).

These calls are relatively conservative.  It may be possible to
optimize these a little more.

Catch up with -current.

Sync with HEAD.

eliminate the KERN_* error codes in favor of the traditional E* codes.
the mapping is:

KERN_SUCCESS			0
KERN_INVALID_ADDRESS		EFAULT
KERN_PROTECTION_FAILURE		EACCES
KERN_NO_SPACE			ENOMEM
KERN_INVALID_ARGUMENT		EINVAL
KERN_FAILURE			various, mostly turn into KASSERTs
KERN_RESOURCE_SHORTAGE		ENOMEM
KERN_NOT_RECEIVER		<unused>
KERN_NO_ACCESS			<unused>
KERN_PAGES_LOCKED		<unused>

Sync with HEAD.

Sync with x68k:
 Use m68k_page_offset and m68k_trunc_page macros,
 instead of using PGOFSET directly.

include sunos_exec.h to declare emul_sunos.

Sync with HEAD

split off thread specific stuff from struct sigacts to struct sigctx, leaving
    only signal handler array sharable between threads
move other random signal stuff from struct proc to struct sigctx

This addresses kern/10981 by Matthew Orgass.

XXX I wish m68k ports would share trap.c

Unification of the m68k syscall() function.

Sync with HEAD.

Sync with HEAD.

s/struct const sysent/const struct sysent/

(BTW, luna68k was missed in emul/execsw changes?)

restructure struct emul and execsw, in preparation to make emulations LKMable:
* move all exec-type specific information from struct emul to execsw[] and
  provide single struct emul per emulation
* elf:
  - kern/exec_elf32.c:probe_funcs[] is gone, execsw[] how has one entry
    per emulation and contains pointer to respective probe function
  - interp is allocated via MALLOC() rather than on stack
  - elf_args structure is allocated via MALLOC() rather than malloc()
* ecoff: the per-emulation hooks moved from alpha and mips specific code
  to OSF1 and Ultrix compat code as appropriate, execsw[] has one entry per
  emulation supporting ecoff with appropriate probe function
* the makecmds/probe functions don't set emulation, pointer to emulation is
  part of appropriate execsw[] entry
* constify couple of structures

Update thorpej_scsipi to -current as of a month ago
A i386 GENERIC kernel compiles without the siop, ahc and bha drivers
(will be updated later). i386 IDE/ATAPI and ncr work, as well as
sparc/esp_sbus. alpha should work as well (untested yet).
siop, ahc and bha will be updated once I've updated the branch to current
-current, as well as machine-dependant code.

file trap.c was added on branch thorpej_scsipi on 2000-11-20 20:16:17 +0000

remove include of <vm/vm.h>. <vm/vm.h> -> <uvm/uvm_extern.h>

remove redudant <vm/pmap.h> includes. <vm/pmap.h> -> <uvm/uvm_pmap.h>

Sync w/ netbsd-1-5-base.

defopt SYSCALL_DEBUG.

Reduce use of curproc in several places:

 - Change ktrace interface to pass in the current process, rather than
p->p_tracep, since the various ktr* function need curproc anyway.

 - Add curproc as a parameter to mi_switch() since all callers had it
handy anyway.

 - Add a second proc argument for inferior() since callers all had
curproc handy.

Also, miscellaneous cleanups in ktrace:

 - ktrace now always uses file-based, rather than vnode-based I/O
(simplifies, increases type safety); eliminate KTRFLAG_FD & KTRFAC_FD.
Do non-blocking I/O, and yield a finite number of times when receiving
EWOULDBLOCK before giving up.

 - move code duplicated between sys_fktrace and sys_ktrace into ktrace_common.

 - simplify interface to ktrwrite()

First sweep at scheduler state cleanup.  Collect MI scheduler
state into global and per-CPU scheduler state:

	- Global state: sched_qs (run queues), sched_whichqs (bitmap
	  of non-empty run queues), sched_slpque (sleep queues).
	  NOTE: These may collectively move into a struct schedstate
	  at some point in the future.

	- Per-CPU state, struct schedstate_percpu: spc_runtime
	  (time process on this CPU started running), spc_flags
	  (replaces struct proc's p_schedflags), and
	  spc_curpriority (usrpri of processes on this CPU).

	- Every platform must now supply a struct cpu_info and
	  a curcpu() macro.  Simplify existing cpu_info declarations
	  where appropriate.

	- All references to per-CPU scheduler state now made through
	  curcpu().  NOTE: this will likely be adjusted in the future
	  after further changes to struct proc are made.

Tested on i386 and Alpha.  Changes are mostly mechanical, but apologies
in advance if it doesn't compile on a particular platform.

Use preempt(), not an open-coded equivalent (which won't be
equivalent for long).

Pull up to last week's -current.

Initial import of news68k port.