Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

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

MFC r262665:
Expose a few DTrace parameters as sysctls under kern.dtrace and add
descriptions for several existing sysctls.

PR: 187027

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

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

Hide references to mod_lock. In FreeBSD it is always acquired with the
provider lock held, so its use has no effect.

Bring back part of r249367 by adding DTrace's temporal option, which allows
users to guarantee that the output of DTrace scripts will be time-ordered.
This option is enabled by adding the line

#pragma D option temporal

to the beginning of a script, or by adding '-x temporal' to the arguments of
dtrace(1).

This change fixes a bug in the original port of the temporal option. This
bug was causing some assertions to fail, so they had been disabled; in this
revision the assertions are working properly and are enabled.

The DTrace version number has been bumped from 1.9.0 to 1.9.1 to reflect
the language change that's being introduced.

This change corresponds to part of illumos-gate commit e5803b76927480:
3021 option for time-ordered output from dtrace(1M)

Reviewed by: pfg
Obtained from: illumos
MFC after: 1 month

Fix warning: comparison of unsigned expression < 0 is always false.

Reported by: clang

Properly cast 64-bit dofhp_dof to pointer.

For i386 this change is no-op. For AMD64 it was tested with DTrace test
suite: results are the same from the test run before the change and after

Kernel DTrace support for:
o uregs (sson@)
o ustack (sson@)
o /dev/dtrace/helper device (needed for USDT probes)

The work done by me was:
Sponsored by: The FreeBSD Foundation

Merge latest DTrace changes from Perforce.

Custom DTrace kernel module files plus FreeBSD-specific DTrace providers.