sys: Remove $FreeBSD$: two-line .h pattern

Remove /^\s*\*\n \*\s+\$FreeBSD\$$\n/

spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD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

hwpmc: use kstack_contains()

This existing helper function is preferable to the hand-rolled
calculation of the kstack bounds.

Make some small style improvements while here. Notably, rename every
instance of "r", the return address, to "ra". Tidy the includes in the
affected files.

Reviewed by: jkoshy
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D39909

PMC: remove now orphaned PMC for INTEL XScale processors.
Support for XScale architecture has been deleted in FreeBSD 13.

Revert r336773: it removed too much.

r336773 removed all things xscale. However, some things xscale are
really armv5. Revert that entirely. A more modest removal will follow.

Noticed by: andrew@

Remove xscale support

The OLD XSCALE stuff hasn't been useful in a while. The original
committer (cognet@) was the only one that had boards for it. He's
blessed this removal. Newer XSCALE (GUMSTIX) is for hardware that's
quite old. After discussion on arm@, it was clear there was no support
for keeping it.

Differential Review: https://reviews.freebsd.org/D16313

sys/arm: 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 arm stack frame walking support:
- Adjust stack offset for Clang
- Correctly fill registers for fake stack frame (soft PMC)

MFC after: 1 week
Sponsored by: Stormshield
Differential Revision: https://reviews.freebsd.org/D7396

Rather than defining our own magic checks here use INKERNEL() for
the PMC_IN_KERNEL() macro definition.

Add missing macros to extract the return address (LR) from the trapframe.

Discussed with: andrew
Obtained from: Cambridge/L41
Sponsored by: DARPA, AFRL
MFC after: 2 weeks

Add ARMv7 performance monitoring counters.

Differential Revision: https://reviews.freebsd.org/D1687
Reviewed by: rpaulo
Sponsored by: DARPA, AFRL

Add ARM callchain support for hwpmc.

Sponsored by: NETASQ
MFC after: 3 days

Soft PMC support for ARM.
Callgraph is not captured, only current location.

Sample system wide profiling: "pmcstat -Sclock.hard -T"

Add software PMC support.

New kernel events can be added at various location for sampling or counting.
This will for example allow easy system profiling whatever the processor is
with known tools like pmcstat(8).

Simultaneous usage of software PMC and hardware PMC is possible, for example
looking at the lock acquire failure, page fault while sampling on
instructions.

Sponsored by: NETASQ
MFC after: 1 month

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

Intel XScale hwpmc(4) support.

This brings hwpmc(4) support for 2nd and 3rd generation XScale cores.
Right now it's enabled by default to make sure we test this a bit.
When the time comes it can be disabled by default.
Tested on Gateworks boards.

A man page is coming.

Obtained from: //depot/user/rpaulo/xscalepmc/...

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

Add stubs to unbreak LINT.

MFP4:

- Implement sampling modes and logging support in hwpmc(4).

- Separate MI and MD parts of hwpmc(4) and allow sharing of
PMC implementations across different architectures.
Add support for P4 (EMT64) style PMCs to the amd64 code.

- New pmcstat(8) options: -E (exit time counts) -W (counts
every context switch), -R (print log file).

- pmc(3) API changes, improve our ability to keep ABI compatibility
in the future. Add more 'alias' names for commonly used events.

- bug fixes & documentation.

Add empty header (except of the multiple-inclusion protection) to
get hwpmc(4) to compile on this platform.