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)

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

MFC r312292, r313573:

Stop including sys/types.h from arm's machine/atomic.h, fix the places
where atomic.h was being included without ensuring that types.h (via
param.h) was included first, as required by atomic(9).

Remove arm's cpuconf.h, and references to it, after moving a few lines from
it into pmap-v4.h where they are used. Other than those few lines of
support for different MMU types, nothing in cpuconf.h has been used in our
code for quite a while.
The file existed to set up a variety of symbols to describe the
architecture. Over the past few years we have converted all of our source
to use the new architecture symbols standardized by ARM Inc, and predefined
by both clang and gcc.

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 stack_save_td_running(), a function to trace the kernel stack of a
running thread.

It is currently implemented only on amd64 and i386; on these
architectures, it is implemented by raising an NMI on the CPU on which
the target thread is currently running. Unlike stack_save_td(), it may
fail, for example if the thread is running in user mode.

This change also modifies the kern.proc.kstack sysctl to use this function,
so that stacks of running threads are shown in the output of "procstat -kk".
This is handy for debugging threads that are stuck in a busy loop.

Reviewed by: bdrewery, jhb, kib
Sponsored by: EMC / Isilon Storage Division
Differential Revision: https://reviews.freebsd.org/D3256

Remove __ARM_EABI__ from sys/arm/arm, building for oabi is unsupported.

Cleanup up ARM *frame structures...

- Eliminate unused irqframe
- Eliminate unused saframe
- Instead of splitting r4-sp storage between the stack and switchframe,
just put all the registers in switchframe and eliminate the un_32 struct.

Submitted by: Svatopluk Kraus <onwahe@gmail.com>,
Michal Meloun <meloun@miracle.cz>

Try to make sure the frame is indeed in the kernel memory.

Add a comment explaining why stack_capture is empty for EABI and clang.

While here add a comment pointing out that, while r11 is not the frame
pointer on EABI as there is no frame pointer, it's value is unused so is
safe.

Don't use the old stack-walking code with
EABI ARM kernels or clang-compiled ARM kernels.

This fixes a crash seen in clang-compiled ARM
kernels that include WITNESS.

This code could be easily modified to walk the stack
for current clang-generated code (including EABI)
but Andrew Turner has raised concerns that the
stack frame currently emitted by clang isn't actually
required by EABI so such a change might cause problems
down the road.

In case anyone wants to experiment, the change
to support current clang-compiled kernels
involves simply setting FR_RFP=0 and FR_SCP=1.

Break out stack(9) from ddb(4):

- Introduce per-architecture stack_machdep.c to hold stack_save(9).
- Introduce per-architecture machine/stack.h to capture any common
definitions required between db_trace.c and stack_machdep.c.
- Add new kernel option "options STACK"; we will build in stack(9) if it is
defined, or also if "options DDB" is defined to provide compatibility
with existing users of stack(9).

Add new stack_save_td(9) function, which allows the capture of a stacktrace
of another thread rather than the current thread, which the existing
stack_save(9) was limited to. It requires that the thread be neither
swapped out nor running, which is the responsibility of the consumer to
enforce.

Update stack(9) man page.

Build tested: amd64, arm, i386, ia64, powerpc, sparc64, sun4v
Runtime tested: amd64 (rwatson), arm (cognet), i386 (rwatson)