MFC r335183:

proc0_post: Fix some locking issues

MFC r283291: don't use CALLOUT_MPSAFE with callout_init()

The main purpose of this MFC is to reduce conflicts for other merges.
Parts of the original change have already "trickled down" via individual MFCs.

MFC r280331:

cred: add proc_set_cred_init helper

PR: D7431

MFC r280130:

cred: add proc_set_cred helper

MFC 295418,295419:
Fix hangs or panics when misbehaved kernel threads return from their
main function.

295418:
Mark proc0 as a kernel process via the P_KTHREAD flag.

All other kernel processes have this flag set and all threads in proc0
(including thread0) have the similar TDP_KTHREAD flag set.

295419:
Call kthread_exit() rather than kproc_exit() for a premature kthread exit.

Kernel threads (and processes) are supposed to call kthread_exit() (or
kproc_exit()) to terminate. However, the kernel includes a fallback in
fork_exit() to force a kthread exit if a kernel thread's "main" routine
returns. This fallback was added back when the kernel only had processes
and was not updated to call kthread_exit() instead of kproc_exit() when
threads were added to the kernel.

This mistake was particularly exciting when the errant thread belonged to
proc0. Due to the missing P_KTHREAD flag the fallback did not kick in
and instead tried to return to userland via whatever garbage was in the
trapframe. With P_KTHREAD set it tried to terminate proc0 resulting in
other amusements.

PR: 204999
Approved by: re (glebius)

MFC r293613:

Implement vsyscall hack. Prior to 2.13 glibc uses vsyscall
instead of vdso. An upcoming linux_base-c6 needs it.

MFC r283382:

In preparation for switching linuxulator to the use the native 1:1
threads add a hook for cleaning thread resources before the thread die.

To facillitate an upcoming Linuxulator merging partially
MFC r275121 (by kib). Only merge the syntax changes from r275121,
PROC_*LOCK() macros still lock the same proc spinlock.

The process spin lock currently has the following distinct uses:

- Threads lifetime cycle, in particular, counting of the threads in
the process, and interlocking with process mutex and thread lock.
The main reason of this is that turnstile locks are after thread
locks, so you e.g. cannot unlock blockable mutex (think process
mutex) while owning thread lock.

- Virtual and profiling itimers, since the timers activation is done
from the clock interrupt context. Replace the p_slock by p_itimmtx
and PROC_ITIMLOCK().

- Profiling code (profil(2)), for similar reason. Replace the p_slock
by p_profmtx and PROC_PROFLOCK().

- Resource usage accounting. Need for the spinlock there is subtle,
my understanding is that spinlock blocks context switching for the
current thread, which prevents td_runtime and similar fields from
changing (updates are done at the mi_switch()). Replace the p_slock
by p_statmtx and PROC_STATLOCK().

Discussed with: kib

MFC: r287183, r287264, r287265

Export kern.features.invariants when kernel is compiled with invariants.

Fix r281843 mis-merge.

Reported by: Thomas Mueller tmueller at sysgo com

MFC revisions 277693,278335,280382-280385,280923-280926,280931,
280933-280939,280974-280976,281002,281009,281081,281176-281180,
281271,281275,281616 (described in-breif below):
r277693: Font fix (des)
r278335: Revert that
r280382: Whitespace, comments, and copyright update
r280383: Prevent inadvertent bootlock condition
r280384: Increase max passowrd length from 16 to 255 chars
r280385: Add missing variable hints to loader.conf(5) defaults
r280923: Whitespace
r280924: Comments
r280925: Optimize bootmsg to use fg/bg/me from screen.4th
r280926: Whitespace and cleanup
r280931: Comments
r280933: Move beastie to logo-*.4th; brands to brand-*.4th
r280934: Add remainder of supported ANSI escape sequences
r280935: Securely overwrite (zero) user input after password checks
r280936: Use equals for ASCII double frames
r280937: Solve dreaded "dictionary full" issue
r280938: Add "GELI Passphrase:" prompt to boot loader
r280939: Revert that (premature commit)
r280974: Use fg/b/me from screen.4th instead of literals
r280975: Eliminate literal escape sequences from *.4th
r280976: Use ^[[m mode-ending versus ^[[37m
r281002: Install newly added brand-*.4th and logo-*.4th files (jkim)
r281009: Revert .PATH changes to fix mips build (jkim)
r281081: Make sure forth manpages are only installed once (bapt)
r281176: Back to previous mode-endings based on feedback
r281177: Back to previous mode-endings based on feedback
r281178: Back to previous mode-endings based on feedback
r281179: Back to previous mode-endings based on feedback
r281180: Eliminate literal escape sequences from *.rc
r281271: Fix a bootlock condition if loader_version is set
NB: Commit message of r281271 has a typo, s/_logo/_version/
r281275: Re-do proper mode-endings
r281616: Add "GELI Passphrase:" prompt to boot loader

Relnotes: Added "GELI Passphrase:" prompt to boot loader

MFC r279361, r279395, r279396:

Allow the kern.osrelease and kern.osreldate sysctl values to be set in a
jail's creation parameters. This allows the kernel version to be reliably
spoofed within the jail whether examined directly with sysctl or
indirectly with the uname -r and -K options.

Export the new osreldate and osrelease jail parms in jail_get(2).

Fix line wrap.

Merge reaper facility.

MFC r270443 (by mjg):
Properly reparent traced processes when the tracer dies.

MFC r273452 (by mjg):
Plug unnecessary PRS_NEW check in kern_procctl.

MFC 275800:
Add a facility for non-init process to declare itself the reaper of
the orphaned descendants.

MFC r275821:
Add missed break.

MFC r275846 (by mckusick):
Add some additional clarification and fix a few gammer nits.

MFC r275847 (by bdrewery):
Bump Dd for r275846.

MFC: r287183, r287264, r287265

Export kern.features.invariants when kernel is compiled with invariants.

Fix r281843 mis-merge.

Reported by: Thomas Mueller tmueller at sysgo com

MFC revisions 277693,278335,280382-280385,280923-280926,280931,
280933-280939,280974-280976,281002,281009,281081,281176-281180,
281271,281275,281616 (described in-breif below):
r277693: Font fix (des)
r278335: Revert that
r280382: Whitespace, comments, and copyright update
r280383: Prevent inadvertent bootlock condition
r280384: Increase max passowrd length from 16 to 255 chars
r280385: Add missing variable hints to loader.conf(5) defaults
r280923: Whitespace
r280924: Comments
r280925: Optimize bootmsg to use fg/bg/me from screen.4th
r280926: Whitespace and cleanup
r280931: Comments
r280933: Move beastie to logo-*.4th; brands to brand-*.4th
r280934: Add remainder of supported ANSI escape sequences
r280935: Securely overwrite (zero) user input after password checks
r280936: Use equals for ASCII double frames
r280937: Solve dreaded "dictionary full" issue
r280938: Add "GELI Passphrase:" prompt to boot loader
r280939: Revert that (premature commit)
r280974: Use fg/b/me from screen.4th instead of literals
r280975: Eliminate literal escape sequences from *.4th
r280976: Use ^[[m mode-ending versus ^[[37m
r281002: Install newly added brand-*.4th and logo-*.4th files (jkim)
r281009: Revert .PATH changes to fix mips build (jkim)
r281081: Make sure forth manpages are only installed once (bapt)
r281176: Back to previous mode-endings based on feedback
r281177: Back to previous mode-endings based on feedback
r281178: Back to previous mode-endings based on feedback
r281179: Back to previous mode-endings based on feedback
r281180: Eliminate literal escape sequences from *.rc
r281271: Fix a bootlock condition if loader_version is set
NB: Commit message of r281271 has a typo, s/_logo/_version/
r281275: Re-do proper mode-endings
r281616: Add "GELI Passphrase:" prompt to boot loader

Relnotes: Added "GELI Passphrase:" prompt to boot loader

MFC r279361, r279395, r279396:

Allow the kern.osrelease and kern.osreldate sysctl values to be set in a
jail's creation parameters. This allows the kernel version to be reliably
spoofed within the jail whether examined directly with sysctl or
indirectly with the uname -r and -K options.

Export the new osreldate and osrelease jail parms in jail_get(2).

Fix line wrap.

Merge reaper facility.

MFC r270443 (by mjg):
Properly reparent traced processes when the tracer dies.

MFC r273452 (by mjg):
Plug unnecessary PRS_NEW check in kern_procctl.

MFC 275800:
Add a facility for non-init process to declare itself the reaper of
the orphaned descendants.

MFC r275821:
Add missed break.

MFC r275846 (by mckusick):
Add some additional clarification and fix a few gammer nits.

MFC r275847 (by bdrewery):
Bump Dd for r275846.