MFC r314556-r314558

r314556:
Correct MDSRCS use in <arch>/string/Makefile.inc.

- Remove .c files which duplicate entries in MISRCS.
- Use the same, less merge conflict prone style in all cases.
- Use MDSRCS for mips (.c and .S files both ended up in SRCS).
- Remove pointless sparc64 Makefile.inc.
- Remove uninformative foreign VCS ID entries.

Reviewed by: emaste, imp, jhb
MFC after: 1 week
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D9841

r314557:
Correct an misunderstanding of MDSRCS.

MDSRCS it intended to allow assembly versions of funtions with C
implementations listed in MISRCS. The selection of the correct
machdep_ldis?.c for a given architecture does not follow this pattern
and the file should be added to SRCS directly.

Reviewed by: emaste, imp, jhb
MFC after: 1 week
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D9841

r314558:
Garbage collect unused gdtoa related files on mips.

Reviewed by: emase, imp, jhb
MFC after: 1 week
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D9841

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

Annotate arm userspace assembler sources stating their tolerance to
the non-executable stack.

Reviewed by: andrew
Sponsored by: The FreeBSD Foundation

Add the needed if-then instructions to build as Thumb-2.

Switch to the ARM unified assembly language as the clang integrated as only
supports it. Binutils supports it when the ".syntax unified" directive
is set.

Sponsored by: ABT Systems Ltd

In ARM asm code, ensure that every ENTRY(foo) has a matching END(foo).
The EABI unwind info requires a .fnend for every .fnstart, and newer
binutils will complain about seeing two .fnstart in a row. This change
allows newer tools to compile our code.

Reported by: bapt
Reviewed by: imp

Merge index() and strchr() together.

As I looked through the C library, I noticed the FreeBSD MIPS port has a
hand-written version of index(). This is nice, if it weren't for the
fact that most applications call strchr() instead.

Also, on the other architectures index() and strchr() are identical,
meaning we have two identical pieces of code in the C library and
statically linked applications.

Solve this by naming the actual file strchr.[cS] and let it use
__strong_reference()/STRONG_ALIAS() to provide the index() routine. Do
the same for rindex()/strrchr().

This seems to make the C libraries and static binaries slightly smaller,
but this reduction in size seems negligible.

The NetBSD Foundation has granted permission to remove clause 3 and 4 from
their software.

Obtained from: NetBSD

- Eliminate extra subcs instruction. I have not noticed before that we
always perform substraction now, so no instruction could be rordered
to eliminate the conditional substraction.

- Fix strncmp on arm. Return 0 as result without performing the
main cycle only if the len passed is equal to 0. If end address
overflows use last possible address as the end address.

Based on: discussion on arm@
MFC after: 1 month

revert r191633; this breaks at91 & xscale (likely all arm)

Change the test at the beginning of strncmp(), from being if (len - 1) < 0
to if (len == 0).
The length is supposed to be unsigned, so len - 1 < 0 won't happen except
if len == 0 anyway, and it would return 0 when it shouldn't, if len was
> INT_MAX.

Spotted out by: Channa <channa kad gmail com>

MFKernel: do not use __XSCALE__ to detect if clz/pld/ldrd/strd are
available, use _ARM_ARCH_5/_ARM_ARCH_5E instead.

MFC After: 3 days

Fix a long line in copyright notice.

Pointed out by: Gavin Atkinson gavin.atkinson ury york ac uk

Add an asm version of strlen() for arm (how useful).

Use the RET macro.
For setjmp() and longjmp(), put the signal mask where it's supposed to be,
instead of in the space reserved for fp regs.

MFKernel: Implement ffs with clz on Xscale.

Always use bx for returning on Xscale.

Obtained from: NetBSD

Fix the align-to-32-bits code.

Obtained from: NetBSD

Import the FreeBSD/arm libc bits.

Obtained from: NetBSD