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 r258625: sdt: add support for solaris/illumos style DTRACE_PROBE macros

Note: in head KDTRACE_HOOKS is defined in opt_global.h and thus there is
no need to explicitly include any header to check that option.
In this branch we have to include opt_kdtrace.h and, so, this commit
carries additional changes to accomodate for that difference.

Sponsored by: HybridCluster

MFC r257152: Do some cleanup of the SDT code

MFC r258622: dtrace sdt: remove the ugly sname parameter of SDT_PROBE_DEFINE

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

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

Give argtype struct names a different prefix than probe struct names.
Otherwise it's possible to declare SDT probes in such a way that a name
collision occurs, causing an unexpected compilation error.

Approved by: re (gjb)
MFC after: 1 week

Add a "translated type" argument to SDT_PROBE_ARGTYPE() and add some macros
which allow one to define SDT probes that specify translated types. The idea
is to make it easy to write SDT probe definitions that can work across
multiple operating systems. In particular, this makes it possible to port
illumos SDT probes to FreeBSD without changing their argument types, so long
as the appropriate translators are defined. Then DTrace scripts written for
Solaris/illumos will work on FreeBSD without any changes.

MFC after: 1 week

FreeBSD's DTrace implementation has a few problems with respect to handling
probes declared in a kernel module when that module is unloaded. In
particular,

* Unloading a module with active SDT probes will cause a panic. [1]
* A module's (FBT/SDT) probes aren't destroyed when the module is unloaded;
trying to use them after the fact will generally cause a panic.

This change fixes both problems by porting the DTrace module load/unload
handlers from illumos and registering them with the corresponding
EVENTHANDLER(9) handlers. This allows the DTrace framework to destroy all
probes defined in a module when that module is unloaded, and to prevent a
module unload from proceeding if some of its probes are active. The latter
problem has already been fixed for FBT probes by checking lf->nenabled in
kern_kldunload(), but moving the check into the DTrace framework generalizes
it to all kernel providers and also fixes a race in the current
implementation (since a probe may be activated between the check and the
call to linker_file_unload()).

Additionally, the SDT implementation has been reworked to define SDT
providers/probes/argtypes in linker sets rather than using SYSINIT/SYSUNINIT
to create and destroy SDT probes when a module is loaded or unloaded. This
simplifies things quite a bit since it means that pretty much all of the SDT
code can live in sdt.ko, and since it becomes easier to integrate SDT with
the DTrace framework. Furthermore, this allows FreeBSD to be quite flexible
in that SDT providers spanning multiple modules can be created on the fly
when a module is loaded; at the moment it looks like illumos' SDT
implementation requires all SDT probes to be statically defined in a single
kernel table.

PR: 166927, 166926, 166928
Reported by: davide [1]
Reviewed by: avg, trociny (earlier version)
MFC after: 1 month

Also define SDT_PROBE_DEFINE0 for the !KDTRACE_HOOKS case.

Add SDT_PROBE_DEFINE0 for consistency with SDT_PROBE0.

MFC after: 1 week

Add macros which allow one to define SDT probes with six or seven arguments;
they are needed when porting some of the Solaris providers (ip, iscsi, and
tcp in particular).

dtrace_probe() only takes five arguments from the probe site, so we need to
add the appropriate cast to allow for more than five arguments. The extra
arguments are later copied out of dtrace_probe()'s stack frame by
dtrace_getarg() (or the provider-specific getarg method) as needed.

MFC after: 1 week

Protect SDT_PROBE() with do { } while (0) loop.

Implement the DTrace sched provider. This implementation aims to be
compatible with the sched provider implemented by Solaris and its open-
source derivatives. Full documentation of the sched provider can be found
on Oracle's DTrace wiki pages.

Note that for compatibility with scripts originally written for Solaris,
serveral probes are defined that will never fire. These probes are defined
to fire when Solaris-specific features perform certain actions. As these
features are not present in FreeBSD, the probes can never fire.

Also, I have added a two probes that are not defined in Solaris, lend-pri
and load-change. These probes have been added to make it possible to
collect schedgraph data with DTrace.

Finally, a few probes are defined in Solaris to take a cpuinfo_t *
argument. As it was not immediately clear to me how to translate that to
FreeBSD, currently those probes are passed NULL in place of a cpuinfo_t *.

Sponsored by: Sandvine Incorporated
MFC after: 2 weeks

Instead of only iterating over the set of known SDT probes when sdt.ko is
loaded and unloaded, also have sdt.ko register callbacks with kern_sdt.c
that will be called when a newly loaded KLD module adds more probes or
a module with probes is unloaded.

This fixes two issues: first, if a module with SDT probes was loaded after
sdt.ko was loaded, those new probes would not be available in DTrace.
Second, if a module with SDT probes was unloaded while sdt.ko was loaded,
the kernel would panic the next time DTrace had cause to try and do
anything with the no-longer-existent probes.

This makes it possible to create SDT probes in KLD modules, although there
are still two caveats: first, any SDT probes in a KLD module must be part
of a DTrace provider that is defined in that module. At present DTrace
only destroys probes when the provider is destroyed, so you can still
panic the system if a KLD module creates new probes in a provider from a
different module(including the kernel) and then unload the the first module.

Second, the system will panic if you unload a module containing SDT probes
while there is an active D script that has enabled those probes.

MFC after: 1 month

SDT's struct sdt_argtype can be marked static everywhere.

It is only passed to SYSINIT/SYSUNINIT.

Add an extra comment to the SDT probes definition. This allows us to get
use '-' in probe names, matching the probe names in Solaris.[1]

Add userland SDT probes definitions to sys/sdt.h.

Sponsored by: The FreeBSD Foundation
Discussed with: rwaston [1]

Add SDT_PROBE[1-5] in the same way we have SDT_PROBE_DEFINE[1-5] to
avoid having to add all the unused trailing arguments as zeros.

MFC after: 6 days

Adding missing ";"'s required by some SDT_PROBE_DEFINEx() macros.

MFC after: 1 week

Reduce the verbosity of SDT trace points for DTrace by defining several
wrapper macros that allow trace points and arguments to be declared
using a single macro rather than several. This means a lot less
repetition and vertical space for each trace point.

Use these macros when defining privilege and MAC Framework trace points.

Reviewed by: jb
MFC after: 1 week

Add the statically defined tracing header.

Note that this implementation differs from the one in OpenSolaris, so
it is BSD licensed and can be included anywhere.

The kernel definitions defined here are dependent on the kernel option
KDTRACE_HOOKS so that macros added to the sources are pre-processed
out completely when the DTrace kernel hooks aren't compiled in.