uio: Use switch statements when handling UIO_READ vs UIO_WRITE

This is mostly to reduce the diff with CheriBSD which adds additional
constants to enum uio_rw, but also matches the normal style used for
uio_segflg.

Reviewed by: kib, emaste
Obtained from: CheriBSD
Differential Revision: https://reviews.freebsd.org/D45142

sys: Automated cleanup of cdefs and other formatting

Apply the following automated changes to try to eliminate
no-longer-needed sys/cdefs.h includes as well as now-empty
blank lines in a row.

Remove /^#if.*\n#endif.*\n#include\s+<sys/cdefs.h>.*\n/
Remove /\n+#include\s+<sys/cdefs.h>.*\n+#if.*\n#endif.*\n+/
Remove /\n+#if.*\n#endif.*\n+/
Remove /^#if.*\n#endif.*\n/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/types.h>/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/param.h>/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/capsicum.h>/

Sponsored by: Netflix

sys: Remove ancient SCCS tags.

Remove ancient SCCS tags from the tree, automated scripting, with two
minor fixup to keep things compiling. All the common forms in the tree
were removed with a perl script.

Sponsored by: Netflix

uiomove: Add some assertions

Make sure that we don't try to copy with a negative resid.

Make sure that we don't walk off the end of the iovec array.

Reviewed by: kib
MFC after: 1 week
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D42098

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

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

pmap_{un}map_io_transient: Use bool instead of boolean_t.

Reviewed by: imp, kib
Differential Revision: https://reviews.freebsd.org/D39920

sys: further adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 3-Clause license.

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.

Special thanks to Wind River for providing access to "The Duke of
Highlander" tool: an older (2014) run over FreeBSD tree was useful as a
starting point.

amd64: make uiomove_fromphys functional for pages not mapped by the DMAP

Place the code introduced in r268660 into a separate function that can be
called from uiomove_fromphys. Instead of pre-allocating two KVA pages use
vmem_alloc to allocate them on demand when needed. This prevents blocking if
a page fault is taken while physical addresses from outside the DMAP are
used, since the lock is now removed.

Also introduce a safety catch in PHYS_TO_DMAP and DMAP_TO_PHYS.

Sponsored by: Citrix Systems R&D
Reviewed by: kib
Differential Revision: https://reviews.freebsd.org/D947

amd64/amd64/pmap.c:
- Factor out the code to deal with non DMAP addresses from pmap_copy_pages
and place it in pmap_map_io_transient.
- Change the code to use vmem_alloc instead of a set of pre-allocated
pages.
- Use pmap_qenter and don't pin the thread if there can be page faults.

amd64/amd64/uio_machdep.c:
- Use pmap_map_io_transient in order to correctly deal with physical
addresses not covered by the DMAP.

amd64/include/pmap.h:
- Add the prototypes for the new functions.

amd64/include/vmparam.h:
- Add safety catches to make sure PHYS_TO_DMAP and DMAP_TO_PHYS are only
used with addresses covered by the DMAP.

Delete stray clause 3 (Advertising clause) and renumber while i'm
here.

Approved by: alc@

Put the general logic for being a CPU hog into a new function
should_yield(). Use this in various places. Encapsulate the common
case of check-and-yield into a new function maybe_yield().

Change several checks for a magic number of iterations to use
should_yield() instead.

MFC after: 1 week

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

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

Begin all license/copyright comments with /*-

Remove checks for curthread == NULL - it can't happen.

Move TDF_DEADLKTREAT into td_pflags (and rename it accordingly) to avoid
having to acquire sched_lock when manipulating it in lockmgr(), uiomove(),
and uiomove_fromphys().

Reviewed by: jhb

Remove advertising clause from University of California Regent's license,
per letter dated July 22, 1999 and permission from Alan Cox.

Approved by: core, alc@

- Add uiomove_fromphys() implementations to alpha and ia64. These only
differ trivially from amd64.
- Correct a spelling error in a comment.

Introduce uiomove_fromphys(). This is a variant of uiomove() that takes
a collection of physical pages as the source. On amd64 it is implemented
using the direct virtual-to-physical map.