Currently these sections are not used but defined only for amd64 and
i386. Added them for all other platforms to keep all platforms in sync.
There should be no functional change.

This change is extracted from a bigger patch [1] of hselasky, with
additional fix for the order of .fini_array section.

1. https://reviews.freebsd.org/D40467

Obtained from:	hselasky
MFC after:	1 week
Differential Revision:	https://reviews.freebsd.org/D45214

Move a copy of amd64's debug code into debug.ldscript. Make all the
kernels use this. This has the effect of modernizing the STABS for
powerpc as the others were almost already in sync. For the ones that
weren't this adds the DWARF 3 debug symbols from i386/amd64.

Sponsored by:		Netflix
Differential Revision:	https://reviews.freebsd.org/D44071

Bring the keeping of .gnu.attributes to all architectures. Also discard
.note.GNU-stack on all archtiectures. Plus delete obsolete comment that
was removed from i386 in 2010.

Sponsored by:		Netflix
Reviewed by:		kib
Differential Revision:	https://reviews.freebsd.org/D44069

Currently there are a few output sections left as implicitly using
:kernel :dynamic before :kernel on its own is used again, which means
they end up in both the PT_LOAD and the PT_DYNAMIC segments, an unusual
situation which the new libelf-based kldxref initially treated as
invalid. Thus, hoist the :kernel to the very next section to ensure only
.dynamic is in PT_DYNAMIC, as is more normal.

Whilst here, sync ldscript.powerpc64le with ldscript.powerpc64 to pick
up various fixes that were presumably made between the start of the
powerpc64le port and it being committed and got missed.

Reviewed by:	jhibbits, jhb
Differential Revision:	https://reviews.freebsd.org/D43066

Remove /^/[*/]\s*\$FreeBSD\$.*\n/

This is a general cleanup of the relocatable kernel support on powerpc,
needed to enable kernel ifuncs.

 * Fix some relocatable issues in the kernel linker, and change to using
   a RELOCATABLE_KERNEL #define instead of #ifdef __powerpc__ for parts that
   other platforms can use in the future if they wish to have ET_DYN kernels.

 * Get rid of the DB_STOFFS hack now that the kernel is relocated to the DMAP
   properly across the board on powerpc64.

 * Add powerpc64 and powerpc32 ifunc functionality.

 * Allow AIM64 virtual mode OF kernels to run from the DMAP like other AIM64
   by implementing a virtual mode restart. This fixes the runtime address on
   PowerMac G5.

 * Fix symbol relocation problems on post-relocation kernels by relocating
   the symbol table.

 * Add an undocumented method for supplying kernel symbols on powernv and
   other powerpc machines using linux-style kernel/initrd loading -- If
   you pass the kernel in as the initrd as well, the copy resident in initrd
   will be used as a source for symbols when initializing the debugger.
   This method is subject to removal once we have a better way of doing this.

Approved by:	jhibbits
Relnotes:	yes
Sponsored by:	Tag1 Consulting, Inc.
Differential Revision:	https://reviews.freebsd.org/D23156

Fix wrong section ordering that was causing a ".got is not contiguous with
other relro sections" lld error. This also brings ldscript.powerpc and
ldscript.powerpcspe closer to ldscript.powerpc64.

Also, remove unnecessary text relocs from the ppc32 AIM trap code.

Approved by: jhibbits (mentor)
Differential Revision: https://reviews.freebsd.org/D22349

After our migration (of certain architectures) to lld the kernel is built
with a unique build-ID.  Make it available via a sysctl and uname(1) to
allow the user to identify their running kernel.

Submitted by:	Ali Mashtizadeh <ali_mashtizadeh.com>
MFC after:	2 weeks
Relnotes:	Yes
Event:		Waterloo Hackathon 2019
Differential Revision:	https://reviews.freebsd.org/D20326

The linker script CONSTRUCTORS keyword is only meaningful "when linking
object file formats which do not support arbitrary sections, such as
ECOFF and XCOFF"[1] and is ignored for other object file formats.

LLVM's lld does not yet accept (and ignore) CONSTRUCTORS, so just remove
CONSTRUCTORS from the linker scripts as it has no effect.

[1] https://sourceware.org/binutils/docs/ld/Output-Section-Keywords.html

Reviewed by:	kib
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D7343

MFC after:	2 months