MFC r324660:

Save VFP state in getcontext(3) on ARM. This is a last followup of r315974,
which fixes userland part of VFP save/restore problems described in PR
217611.

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

Make armv6 hard float abi by default. Kill armv6hf.
Allow CPUTYPE=soft to build the current soft-float abi libraries.
Add UPDATING entry to announce this.

Approved by: re@ (gjb)

Remove duplicate copies of trivial getcontextx.c

Only i386 and amd64 provide a non-trivial __getcontextx(). Use a common
trivial implementation in gen/ for other architectures, rather than
copying the file to each MD subdirectory.

Reviewed by: kib
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D1472

Remove MK_ARM_EABI, the armeb issues have been fixed. The code to support
the oabi is still in the tree, but it is expected this will be removed
as developers work on surrounding code.

With this commit the ARM EABI is the only supported supported ABI by
FreeBSD on ARMa 32-bit processors.

X-MFC after: never
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D876

Rename the fp{get,set}* files so they no longer conflict with the softfloat
version of these files. Keep them within this directory so they can be used
to implement the armv6 version of these functions.

Add the deprecated fp{get,set}* functions, a few ports use them.

Finish pulling in the NetBSD setjmp/longjmp updates on ARM.

Store/restore the VFP registers in setjmp/longjmp on ARM EABI if VFP is
enabled in the kernel. It checks the hw.floatingpoint sysctl to see if
floating-point is available and uses this to determine if it should store
them. If it does it uses a different magic value so longjmp is able to know
if it should load them.

Use the compiler-rt version __{u,}divsi3 and __{u,}modsi3 on ARM EABI

Replace the C implementation of __aeabi_read_tp with an assembly version.
This ensures we follow the ABI by preserving registers r1-r3.

Reviewed by: jmallett, imp

- Revert part of r234005, which I did not intend to commit.
Sorry! :(

- Add kernel config file for QEMU-emulated gumstix board.

Add __aeabi_read_tp function required for thread-local storage

Reviewed by: cognet

Add API for obtaining extended machine context states that cannot be
fit into existing mcontext_t.

On i386 and amd64 do return the extended FPU states using
getcontextx(3). For other architectures, getcontextx(3) returns the
same information as getcontext(2).

Tested by: pho
MFC after: 1 month

Implement FLT_ROUNDS for arm. Some (all?) arm FPUs lack support for
dynamic rounding modes, but FPUless chips that use softfloat can support it
because everything is emulated anyway. (We presently have incomplete
support for hardware FPUs.)

Submitted by: Ian Lepore

Replace a proliferation of buggy MD implementations of modf() with a
working MI one. The MI one only needs to be overridden on machines
with non-IEEE754 arithmetic. (The last supported one was the VAX.)
It can also be overridden if someone comes up with a faster one that
actually passes the regression tests -- but this is harder than it sounds.

Add a dummy set_tp().

Replace seven nominally MD implementations of frexp() that are broken
for subnormals with one implementation that works.

Implement the classification macros isfinite(), isinf(), isnan(), and
isnormal() the hard way, rather than relying on fpclassify(). This is
a lose in the sense that we need a total of 12 functions, but it is
necessary for binary compatibility because we have never bumped libm's
major version number. In particular, isinf(), isnan(), and isnanf()
were BSD libc functions before they were C99 macros, so we can't
reimplement them in terms of fpclassify() without adding a dependency
on libc.so.5. I have tried to arrange things so that programs that
could be compiled in FreeBSD 4.X will generate the same external
references when compiled in 5.X. At the same time, the new macros
should remain C99-compliant.

The isinf() and isnan() functions remain in libc for historical
reasons; however, I have moved the functions that implement the macros
isfinite() and isnormal() to libm where they belong. Moreover,
half a dozen MD versions of isinf() and isnan() have been replaced
with MI versions that work equally well.

Prodded by: kris

Import the FreeBSD/arm libc bits.

Obtained from: NetBSD