Revert r330897:

This was intended to be a non-functional change. It wasn't. The commit
message was thus wrong. In addition it broke arm, and merged crypto
related code.

Revert with prejudice.

This revert skips files touched in r316370 since that commit was since
MFCed. This revert also skips files that require $FreeBSD$ property
changes.

Thank you to those who helped me get out of this mess including but not
limited to gonzo, kevans, rgrimes.

Requested by: gjb (re)

MFC r328087 (by fabient):
Fix pmcstat exit from kernel introduced by r325275.

PR: 223689

Partial merge of the SPDX changes

These changes are incomplete but are making it difficult
to determine what other changes can/should be merged.

No objections from: pfg

Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

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

Add software PMC support.

New kernel events can be added at various location for sampling or counting.
This will for example allow easy system profiling whatever the processor is
with known tools like pmcstat(8).

Simultaneous usage of software PMC and hardware PMC is possible, for example
looking at the lock acquire failure, page fault while sampling on
instructions.

Sponsored by: NETASQ
MFC after: 1 month

Fix memory leak on error.

Found with: Coverity Prevent(tm)
MFC after: 1 month

- Add support for PMCs in Intel CPUs of Family 6, model 0xE (Core Solo
and Core Duo), models 0xF (Core2), model 0x17 (Core2Extreme) and
model 0x1C (Atom).

In these CPUs, the actual numbers, kinds and widths of PMCs present
need to queried at run time. Support for specific "architectural"
events also needs to be queried at run time.

Model 0xE CPUs support programmable PMCs, subsequent CPUs
additionally support "fixed-function" counters.

- Use event names that are close to vendor documentation, taking in
account that:
- events with identical semantics on two or more CPUs in this family
can have differing names in vendor documentation,
- identical vendor event names may map to differing events across
CPUs,
- each type of CPU supports a different subset of measurable
events.

Fixed-function and programmable counters both use the same vendor
names for events. The use of a class name prefix ("iaf-" or
"iap-" respectively) permits these to be distinguished.

- In libpmc, refactor pmc_name_of_event() into a public interface
and an internal helper function, for use by log handling code.

- Minor code tweaks: staticize a global, freshen a few comments.

Tested by: gnn

Add callchain parsing to -lpmc.

Sponsored by: FreeBSD Foundation and Google Inc.

MFP4: Support for profiling dynamically loaded objects.

Kernel changes:

Inform hwpmc of executable objects brought into the system by
kldload() and mmap(), and of their removal by kldunload() and
munmap(). A helper function linker_hwpmc_list_objects() has been
added to "sys/kern/kern_linker.c" and is used by hwpmc to retrieve
the list of currently loaded kernel modules.

The unused `MAPPINGCHANGE' event has been deprecated in favour
of separate `MAP_IN' and `MAP_OUT' events; this change reduces
space wastage in the log.

Bump the hwpmc's ABI version to "2.0.00". Teach hwpmc(4) to
handle the map change callbacks.

Change the default per-cpu sample buffer size to hold
32 samples (up from 16).

Increment __FreeBSD_version.

libpmc(3) changes:

Update libpmc(3) to deal with the new events in the log file; bring
the pmclog(3) manual page in sync with the code.

pmcstat(8) changes:

Introduce new options to pmcstat(8): "-r" (root fs path), "-M"
(mapfile name), "-q"/"-v" (verbosity control). Option "-k" now
takes a kernel directory as its argument but will also work with
the older invocation syntax.

Rework string handling in pmcstat(8) to use an opaque type for
interned strings. Clean up ELF parsing code and add support for
tracking dynamic object mappings reported by a v2.0.00 hwpmc(4).

Report statistics at the end of a log conversion run depending
on the requested verbosity level.

Reviewed by: jhb, dds (kernel parts of an earlier patch)
Tested by: gallatin (earlier patch)

Fix a bug in pmclog_read() that causes it to return with a false
error when a log record crosses an internal buffer boundary.

Approved by: re (scottl)

MFP4:

- pmcstat(8) gprof output mode fixes:

lib/libpmc/pmclog.{c,h}, sys/sys/pmclog.h:
+ Add a 'is_usermode' field to the PMCLOG_PCSAMPLE event
+ Add an 'entryaddr' field to the PMCLOG_PROCEXEC event,
so that pmcstat(8) can determine where the runtime loader
/libexec/ld-elf.so.1 is getting loaded.

sys/kern/kern_exec.c:
+ Use a local struct to group the entry address of the image being
exec()'ed and the process credential changed flag to the exec
handling hook inside hwpmc(4).

usr.sbin/pmcstat/*:
+ Support "-k kernelpath", "-D sampledir".
+ Implement the ELF bits of 'gmon.out' profile generation in a new
file "pmcstat_log.c". Move all log related functions to this
file.
+ Move local definitions and prototypes to "pmcstat.h"

- Other bug fixes:
+ lib/libpmc/pmclog.c: correctly handle EOF in pmclog_read().
+ sys/dev/hwpmc_mod.c: unconditionally log a PROCEXIT event to all
attached PMCs when a process exits.
+ sys/sys/pmc.h: correct a function prototype.
+ Improve usage checks in pmcstat(8).

Approved by: re (blanket hwpmc)

MFP4:

- Implement sampling modes and logging support in hwpmc(4).

- Separate MI and MD parts of hwpmc(4) and allow sharing of
PMC implementations across different architectures.
Add support for P4 (EMT64) style PMCs to the amd64 code.

- New pmcstat(8) options: -E (exit time counts) -W (counts
every context switch), -R (print log file).

- pmc(3) API changes, improve our ability to keep ABI compatibility
in the future. Add more 'alias' names for commonly used events.

- bug fixes & documentation.