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 $FreeBSD$: one-line .c pattern

Remove /^[\s*]*__FBSDID\("\$FreeBSD\$"\);?\s*\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spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD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

Optimize res_find().

When the device name is provided, we can simply run strncmp() for each
line to quickly skip unrelated ones, that is much faster than sscanf()
and only then strcmp().

MFC after: 2 weeks

Move kernel env global variables, etc to sys/kenv.h

The kernel globals for kenv are confined to 2 files that need them and
a few that likely shouldn't (but as written the code does). Move them
from sys/systm.h to sys/kenv.h. This removed a XXX from systm.h and
cleans it up a little bit...

Remove duplicated empty lines from kern/*.c

No functional changes.

res_find: Fix fallback logic

The fallback logic was broken if hints were found in multiple environments.
If we found a hint in either the loader environment or the static
environment, fallback would be incremented excessively when we returned to
the environment-selection bits. These checks should have also been guarded
by the fbacklvl checks. As a result, fbacklvl could quickly get to a point
where we skip either the static environment and/or the static hints
depending on which environments contained valid hints.

The impact of this bug is minimal, mostly affecting mips boards that use
static hints and may have hints in either the loader environment or the
static environment.

There may be better ways to express the searchable environments and
describing their characteristics (immutable, already searched, etc.) but
this may be revisited after 12 branches.

Reported by: Dan Nelson <dnelson_1901@yahoo.com>
Triaged by: Dan Nelson <dnelson_1901@yahoo.com>
MFC after: 3 days

subr_hints: Skip static_env and static_hints if they don't contain hints

This is possible because, well, they're static. Both the dynamic environment
and the MD-environment (generally loader(8) environment) can potentially
have room for new variables to be set, and thus do not receive this
treatment.

subr_hints: Convert some bool-like ints to bools

subr_hints: Use goto/label instead of series of conditionals

kern_environment: Fix SYSINIT ordering

The dynamic environment was being initialized at SI_SUB_KMEM, SI_ORDER_ANY.
I added the hint-merging at SI_SUB_KMEM, SI_ORDER_ANY as well in r335998 -
this can only work by coincidence.

Re-do both to operate at SI_SUB_KMEM + 1, SI_ORDER_FIRST and SI_ORDER_SECOND
respectively to be safe. It's sufficiently obfuscated away as to when in
SU_SUB_KMEM malloc will be available, and the dynamic environment cannot be
relied upon there anyways since it's initialized at SI_ORDER_ANY.

Reported by: bde
Discussed with: bde
X-MFC-With: r335998

kern_environment: use any provided environments, evict hintmode/envmode

At the moment, hintmode and envmode are used to indicate whether static
hints or static env have been provided in the kernel config(5) and the
static versions are mutually exclusive with loader(8)-provided environment.
hintmode *can* be reconfigured later to pull from the dynamic environment,
thus taking advantage of the loader(8) or post-kmem environment setting.

This changeset fixes both problems at once to move us from a semi-confusing
state to a consistent state: if an environment file, hints file, or
loader(8) environment are provided, we use them in a well-known order of
precedence:

- loader(8) environment
- static environment
- static hints file

Once the dynamic environment is setup this becomes a moot point. The
loader(8) and static environments are merged (respecting the above order of
precedence), and the static hints are merged in on an as-needed basis after
the dynamic environment has been setup.

Hints lookup are changed to respect all of the above. Before the dynamic
environment is setup, lookups use the above-mentioned order and fallback to
the next environment if a matching hint is not found. Once the dynamic
environment is setup, that is used on its own since it captures all of the
above information plus any dynamic kenv settings that came up later in boot.

The following tangentially related changes were made to res_find:

- A hintp cookie is now passed in so that related searches continue using
the chain of environments (or dynamic environment) without relying on
global state
- All three environments will be searched if they actually have valid hints
to use, rather than just choosing the first environment that actually had
a hint and rolling with that only

The hintmode sysctl has been ripped out. static_{env,hints}.disabled are
still honored and will disable their respective environments from being used
for hint lookups and from being merged into the dynamic environment, as
expected.

MFC after: 1 month (maybe)
Differential Revision: https://reviews.freebsd.org/D15953

Revert r335995 due to accidental changes snuck in

kern_environment: use any provided environments, evict hintmode/envmode

At the moment, hintmode and envmode are used to indicate whether static
hints or static env have been provided in the kernel config(5) and the
static versions are mutually exclusive with loader(8)-provided environment.
hintmode *can* be reconfigured later to pull from the dynamic environment,
thus taking advantage of the loader(8) or post-kmem environment setting.

This changeset fixes both problems at once to move us from a semi-confusing
state to a consistent state: if an environment file, hints file, or
loader(8) environment are provided, we use them in a well-known order of
precedence:

- loader(8) environment
- static environment
- static hints file

Once the dynamic environment is setup this becomes a moot point. The
loader(8) and static environments are merged (respecting the above order of
precedence), and the static hints are merged in on an as-needed basis after
the dynamic environment has been setup.

Hints lookup are changed to respect all of the above. Before the dynamic
environment is setup, lookups use the above-mentioned order and fallback to
the next environment if a matching hint is not found. Once the dynamic
environment is setup, that is used on its own since it captures all of the
above information plus any dynamic kenv settings that came up later in boot.

The following tangentially related changes were made to res_find:

- A hintp cookie is now passed in so that related searches continue using
the chain of environments (or dynamic environment) without relying on
global state
- All three environments will be searched if they actually have valid hints
to use, rather than just choosing the first environment that actually had
a hint and rolling with that only

The hintmode sysctl has been ripped out. static_{env,hints}.disabled are
still honored and will disable their respective environments from being used
for hint lookups and from being merged into the dynamic environment, as
expected.

MFC after: 1 month (maybe)
Differential Revision: https://reviews.freebsd.org/D15953

subr_hints: Fix acpi unit hinting (at the very least)

The refactoring in r335479 overlooked the fact that the dynamic kenv can
also be switched to if hintmode == 0. This is problematic because the
checkmethod bits are only ever ran once, but it worked previously because
the use_kenv was a global state and the first lookup would enable it if
occurring after the dynamic environment has been setup.

Extending our local definition of use_kenv to include all non-STATIC
hintmodes as long as the dynamic_kenv is setup fixes this. We still have
potential issues if the dynamic kenv comes up while we're doing an anchored
search through the environment, but this is not much of a concern right now
because:

1.) The dynamic environment comes up super early in boot, just after kmem

2.) This is going to get rewritten to provide a safer mechanism for the
anchored searches, ensuring that we continue using the same environment
chain (dynamic env or static fallback) for all anchored search invocations

Reported by: mmamcy
X-MFC-With: r335479

subr_hints: simplify a little bit

Some complexity exists in these bits that isn't needed. The sysctl handler,
upon change to '2', runs through the current set of hints and sets them in
the kenv.

However, this isn't at all necessary if we're pulling hints from the kenv,
static or dynamic, as the former will get added to the latter in
init_dynamic_kenv (see: kern_environment.c). We can reduce this
configuration to just adding static_hints to the kenv if we were previously
using them.

The changes in res_find are minimal and based on the observation that once
use_kenv gets set to '1' it will never be reset to '0', and it gets set to
'1' as soon as we hit fallback mode. Later work will refactor res_find a
little bit and eliminate this now-local, because it's become clear that
there's some funkiness revolving around use_kenv=1 and it being used to
imply that we're certainly looking at the dynamic_kenv.

Reviewed by: ray
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D15940

sys/kern: 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.

Add a new device control utility for new-bus devices called devctl. This
allows the user to request administrative changes to individual devices
such as attach or detaching drivers or disabling and re-enabling devices.
- Add a new /dev/devctl2 character device which uses ioctls for device
requests. The ioctls use a common 'struct devreq' which is somewhat
similar to 'struct ifreq'.
- The ioctls identify the device to operate on via a string. This
string can either by the device's name, or it can be a bus-specific
address. (For unattached devices, a bus address is the only way to
locate a device.) Bus drivers register an eventhandler to claim
unrecognized device names that the driver recognizes as a valid address.
Two buses currently support addresses: ACPI recognizes any device
in the ACPI namespace via its full path starting with "\" and
the PCI bus driver recognizes an address specification of
'pci[<domain>:]<bus>:<slot>:<func>' (identical to the PCI selector
strings supported by pciconf).
- To make it easier to cut and paste, change the PnP location string
in the PCI bus driver to output a full PCI selector string rather
than 'slot=<slot> function=<func>'.
- Add a devctl(3) interface in libdevctl which provides a wrapper around
the ioctls and is the preferred interface for other userland code.
- Add a devctl(8) program which is a simple wrapper around the requests
supported by devctl(3).
- Add a device_is_suspended() function to check DF_SUSPENDED.
- Add a resource_unset_value() function that can be used to remove a
hint from the kernel environment. This is used to clear a
hint.<driver>.<unit>.disabled hint when re-enabling a boot-time
disabled device.

Reviewed by: imp (parts)
Requested by: imp (changing PCI location string)
Relnotes: yes

Follow up to r225617. In order to maximize the re-usability of kernel code
in userland rename in-kernel getenv()/setenv() to kern_setenv()/kern_getenv().
This fixes a namespace collision with libc symbols.

Submitted by: kmacy
Tested by: make universe

Preserve one character space for a trailing '\0'.

Found by: Ivan Klymenko via cppcheck
Discussed with: ae
MFC after: 1 week

Style fixes.

Suggested by: mdf
Approved by: adrian (menthor)

Add missing braces.

Approved by: bschmidt (while mentor offline)
Pointed by: gcooper
Pointy hat to: ray

Add kern.hintmode sysctl variable to show current state of hints:
0 - loader hints in environment only;
1 - static hints only
2 - fallback mode (Dynamic KENV with fallback to kernel environment)
Add kern.hintmode write handler, accept only value 2. That will switch
static KENV to dynamic. So it will be possible to change device hints.

Approved by: adrian (mentor)

Use strchr() and strrchr().

It seems strchr() and strrchr() are used more often than index() and
rindex(). Therefore, simply migrate all kernel code to use it.

For the XFS code, remove an empty line to make the code identical to
the code in the Linux kernel.

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.

Use a sleep mutex instead of an sx lock for the kernel environment. This
allows greater flexibility for drivers that want to query the environment.

Reviewed by: jhb, mux

The resource_xxx routines in subr_hints.c are called before and after the
kenv environment in kern_environment.c switches to dynamic kenv. The prior
call sets the static variable hintp to the static hints in subr_hints.c
(hintmode==0).

However, changes to the environment are not detected by the resource_xxx
lookups after the change to dynamic kernel environment, so the lookup
routines only report the old stuff of hintmode==0, even after the change to
the dynamic kenv. This causes kenv users to see a different environment than
the kernel routines.

This is a problem in the mixer.c code that looks up initial mixer volume
settings from the hints: If the hints are dynamic and not from the
device.hints file, mixer.c doesn't see them, but kenv does.

The patch from the PR (modified to comply to the style of the function)
solves this.

PR: 83686
Submitted by: Harry Coin <harrycoin@qconline.com>

Don't set ret_namelen and ret_resnamelen in res_find() unless both the
corresponding pointer to the buffer (ret_name and ret_resname) is non-NULL
to avoid possible NULL pointer derefs.

Reported by: Coverity via sam

fix spelling of match in comment...

MFC after: 3 days

Add a resource_disabled() helper function that returns true (non-zero) if
a specified resource has been disabled via a non-zero 'disabled' hint and
false otherwise.

Use __FBSDID().

Cosmetic tweaks. Try and keep the style more consistent, catch some stray
whitespace and update a comment.

Finish fixing hints. Remember the use_kenv state for the next run.
Otherwise we fall back to using the static hints the next time around.
We still have the leftover fallback code there which meant that we skipped
the use_hints checking on the second and subsequent calls. Also, be a bit
more careful about walking off the end of the envp array.

I've extracted this from a larger diff. I hope I didn't miss anything...

Partial fix for hints

Obtained from: mux

Rework the kernel environment subsystem. We now convert the static
environment needed at boot time to a dynamic subsystem when VM is
up. The dynamic kernel environment is protected by an sx lock.

This adds some new functions to manipulate the kernel environment :
freeenv(), setenv(), unsetenv() and testenv(). freeenv() has to be
called after every getenv() when you have finished using the string.
testenv() only tests if an environment variable is present, and
doesn't require a freeenv() call. setenv() and unsetenv() are self
explanatory.

The kenv(2) syscall exports these new functionalities to userland,
mainly for kenv(1).

Reviewed by: peter

Fix a fatal type mismatch (char *static_env; vs char static_env[]).

Submitted by: bde

Go back to having either static OR dynamic hints, with fallback
support. Trying to fix the merged set where dynamic overrode
static was getting more and more complicated by the day.

This should fix the duplicate atkbd, psm, fd* etc in GENERIC. (which
paniced the alpha, but not the i386)

Hints overhaul:
- Replace some very poorly thought out API hacks that should have been
fixed a long while ago.
- Provide some much more flexible search functions (resource_find_*())
- Use strings for storage instead of an outgrowth of the rather
inconvenient temporary ioconf table from config(). We already had a
fallback to using strings before malloc/vm was running anyway.