Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Change the - hopefully - last piece of ktr(9) to use PCPU_GET(cpuid)
instead of the MD module ID for KTR_CPU.

- (Ab)use udivx for dividing the u_int pc_cpuid when implementing
CPU_ISSET(), CPU_SET etc. in sparc64 asm. This approach has the
benefit of not clobbering %y, allowing to revert r222827 and
partially r222828.
- In r222828, CATR() already was changed to use the equivalent of
PCPU_GET(cpuid) instead of the MD module ID for KTR_CPU, so
belatedly also catch up with the C side of ktr(9). Originally,
in r203838 CATR() was moved away from directly reading the
module ID or equivalent as that became impractical with other
CPU types than USI/II supported. With r222828 in place, per-CPU
data generally is set up soon enough, though, that employing
PCPU things in ktr(9) also for use during early stages works.
- Unfortunately, an exception to the latter is the ktr(9) use
in pmap_bootstrap(), which actually is run so early that even
checking for bootverbose being set via the loader doesn't work.
Consequently, replace the ktr(9) use in pmap_bootstrap() with
OF_printf(9) and put it under #ifdef DIAGNOSTIC instead.

MFC after: 3 days

Adapt CATR() to r283283.

- Implement run-time expansion of the KTR buffer via sysctl.
- Implement a function to ensure that all preempted threads have switched
back out at least once. Use this to make sure there are no stale
references to the old ktr_buf or the lock profiling buffers before
updating them.

Reviewed by: marius (sparc64 parts), attilio (earlier patch)
Sponsored by: EMC / Isilon Storage Division

Adapt CATR() to r222813. This is somewhat tricky as we can't afford using
more than three temporary register in several places CATR() is used so
this code trades instructions in for registers. Actually, this still isn't
sufficient and CATR() has the side-effect of clobbering %y. Luckily, with
the current uses of CATR() this either doesn't matter or we are able to
(save and) restore it.
Now that there's only one use of AND() and TEST() left inline these.

etire the cpumask_t type and replace it with cpuset_t usage.

This is intended to fix the bug where cpu mask objects are
capped to 32. MAXCPU, then, can now arbitrarely bumped to whatever
value. Anyway, as long as several structures in the kernel are
statically allocated and sized as MAXCPU, it is suggested to keep it
as low as possible for the time being.

Technical notes on this commit itself:
- More functions to handle with cpuset_t objects are introduced.
The most notable are cpusetobj_ffs() (which calculates a ffs(3)
for a cpuset_t object), cpusetobj_strprint() (which prepares a string
representing a cpuset_t object) and cpusetobj_strscan() (which
creates a valid cpuset_t starting from a string representation).
- pc_cpumask and pc_other_cpus are target to be removed soon.
With the moving from cpumask_t to cpuset_t they are now inefficient
and not really useful. Anyway, for the time being, please note that
access to pcpu datas is protected by sched_pin() in order to avoid
migrating the CPU while reading more than one (possible) word
- Please note that size of cpuset_t objects may differ between kernel
and userland. While this is not directly related to the patch itself,
it is good to understand that concept and possibly use the patch
as a reference on how to deal with cpuset_t objects in userland, when
accessing kernland members.
- KTR_CPUMASK is changed and now is represented through a string, to be
set as the example reported in NOTES.

Please additively note that no MAXCPU is bumped in this patch, but
private testing has been done until to MAXCPU=128 on a real 8x8x2(htt)
machine (amd64).

Please note that the FreeBSD version is not yet bumped because of
the upcoming pcpu changes. However, note that this patch is not
targeted for MFC.

People to thank for the time spent on this patch:
- sbruno, pluknet and Nicholas Esborn (nick AT desert DOT net) tested
several revision of the patches and really helped in improving
stability of this work.
- marius fixed several bugs in the sparc64 implementation and reviewed
patches related to ktr.
- jeff and jhb discussed the basic approach followed.
- kib and marcel made targeted review on some specific part of the
patch.
- marius, art, nwhitehorn and andreast reviewed MD specific part of
the patch.
- marius, andreast, gonzo, nwhitehorn and jceel tested MD specific
implementations of the patch.
- Other people have made contributions on other patches that have been
already committed and have been listed separately.

Companies that should be mentioned for having participated at several
degrees:
- Yahoo! for having offered the machines used for testing on big
count of CPUs.
- The FreeBSD Foundation for having sponsored my devsummit attendance,
which has been instrumental.
- Sandvine for having offered offices and infrastructure during
development.

(I really hope I didn't forget anyone, if it happened I apologize in
advance).

- Search the whole OFW device tree instead of only the children of the
root nexus device for the CPUs as starting with UltraSPARC IV the 'cpu'
nodes hang off of from 'cmp' (chip multi-threading processor) or 'core'
or combinations thereof. Also in large UltraSPARC III based machines
the 'cpu' nodes hang off of 'ssm' (scalable shared memory) nodes which
group snooping-coherency domains together instead of directly from the
nexus.
It would be great if we could use newbus to deal with the different ways
the 'cpu' devices can hang off of pseudo ones but unfortunately both
cpu_mp_setmaxid() and sparc64_init() have to work prior to regular device
probing.
- Add support for UltraSPARC IV and IV+ CPUs. Due to the fact that these
are multi-core each CPU has two Fireplane config registers and thus the
module/target ID has to be determined differently so the one specific
to a certain core is used. Similarly, starting with UltraSPARC IV the
individual cores use a different property in the OFW device tree to
indicate the CPU/core ID as it no longer is in coincidence with the
shared slot/socket ID.
This involves changing the MD KTR code to not directly read the UPA
module ID either. We use the MID stored in the per-CPU data instead of
calling cpu_get_mid() as a replacement in order prevent clobbering any
registers as side-effect in the assembler version. This requires CATR()
invocations from mp_startup() prior to mapping the per-CPU pages to be
removed though.
While at it additionally distinguish between CPUs with Fireplane and
JBus interconnects as these also use slightly different sizes for the
JBus/agent/module/target IDs.
- Make sparc64_shutdown_final() static as it's not used outside of
machdep.c.

Use <sys/ktr.h> directly in .S files instead of exporting the
KTR_* class macros via genassym.c. Together with sys/sys/ktr.h
rev. 1.34 this has the desired side-effect of providing a default
value for KTR_COMPILE. Thus this fixes warnings from -Wundef
regarding KTR_COMPILE not being defined for .S files.

Requested by: ru
Reviewed by: ru

Two tokens that don't together form a vaid preprocssor token cannot be
pasted together using ANSI-C token concatinatation. GCC's cpp, at least,
produces the desired result w/o using "##".

Provide an implementation of KTR_CPU that doesn't use pcpu, so we don't
crash and burn if its not setup yet. Add timestamp, cpu, and (fake) file
and line recording to the asm version of CTR.

Remove an unused macro arg.

Don't overflow the ktr buffer <gulp>.

Add simple macros for tracing in assembler files. There are quite
a few places where we cannot even call a function, and these have
proven to be very useful debugging tools for such situations.