sys: Remove $FreeBSD$: two-line .h pattern

Remove /^\s*\*\n \*\s+\$FreeBSD\$$\n/

dtrace: rename rp to frame in dtrace_getreg()

Reviewed by: mhorne, markj
Approved by: markj (mentor)
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D40231

dtrace: remove unused defines

Reviewed by: markj, emaste
MFC after: 3 days
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D37659

Create sys/reg.h for the common code previously in machine/reg.h

Move the common kernel function signatures from machine/reg.h to a new
sys/reg.h. This is in preperation for adding PT_GETREGSET to ptrace(2).

Reviewed by: imp, markj
Sponsored by: DARPA, AFRL (original work)
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D19830

As <machine/vmparam.h> is included from <vm/vm_param.h>, there is no
need to include it explicitly when <vm/vm_param.h> is already included.

Suggested by: alc
Reviewed by: alc
Differential Revision: https://reviews.freebsd.org/D5379

On ARM, unlike some other architectures, saved $pc values from in-kernel
traps do appear in the regular call stack, rather than only in a special
trap frame, so we don't need to inject the trap-frame $pc into a returned
stack trace in DTrace.

MFC after: 3 days
Sponsored by: DARPA, AFRL

Fix the dtrace ARM atomic compare-and-set functions. These functions are
expected to return the data in the memory location pointed at by target
after the operation. The FreeBSD atomic functions previously used return
either 0 or 1 to indicate if the comparison succeeded or not respectively.

With this change these functions only support ARMv6 and later are supported
by these functions.

Sponsored by: ABT Systems Ltd

Use the ARM unwinder with dtrace to extract the stack when asked. With this
dtrace is able to display a stack trace similar to the one below.

# dtrace -p 603 -n 'tcp:kernel::receive { stack(); }'
0 70 :receive
kernel`ip_input+0x140
kernel`netisr_dispatch_src+0xb8
kernel`ether_demux+0x1c4
kernel`ether_nh_input+0x3a8
kernel`netisr_dispatch_src+0xb8
kernel`ether_input+0x60
kernel`cpsw_intr_rx+0xac
kernel`intr_event_execute_handlers+0x128
kernel`ithread_loop+0xb4
kernel`fork_exit+0x84
kernel`swi_exit
kernel`swi_exit

Tested by: gnn
Sponsored by: ABT Systems Ltd

Initial version of DTrace on ARM32.

Submitted by: Howard Su based on work by Oleksandr Tymoshenko
Reviewed by: ian, andrew, rpaulo, markj