loader: rename gfx_interp_md to gfx_interp_ref

We have the call to gfx_interp_ref to bring in the .o so that we get the
linker set item to add the language bindings at the right time. Where we
call it is not the right time... So the _ref name is better. Change it
before we have too many others like it.

Sponsored by: Netflix

libsa: Remove redundant sys/cdefs.h

Sponsored by: Netflix

loader: Add prototype for gfx_interp_md

This function will be used to draw in the graphics bindings when the
loader is compiled with graphics (gfx) support. Provide definitions
for lua and the simple interpreter. 4th support is forthcoming.

Sponsored by: Netflix
Reviewed by: kevans, jhb
Differential Revision: https://reviews.freebsd.org/D43903

Remove $FreeBSD$: one-line .c pattern

Remove /^[\s*]*__FBSDID\("\$FreeBSD\$"\);?\s*\n/

veloader use vectx API for kernel and modules

The vectx API, computes the hash for verifying a file as it is read.
This avoids the overhead of reading files twice - once to verify, then
again to load.

For doing an install via loader, avoiding the need to rewind
large files is critical.

This API is only used for modules, kernel and mdimage as these are the
biggest files read by the loader.
The reduction in boot time depends on how expensive the I/O is
on any given platform. On a fast VM we see 6% improvement.

For install via loader the first file to be verified is likely to be the
kernel, so some of the prep work (finding manifest etc) done by
verify_file() needs to be factored so it can be reused for
vectx_open().

For missing or unrecognized fingerprint entries, we fail
in vectx_open() unless verifying is disabled.

Otherwise fingerprint check happens in vectx_close() and
since this API is only used for files which must be verified
(VE_MUST) we panic if we get an incorrect hash.

Reviewed by: imp,tsoome
MFC after: 1 week
Sponsored by: Juniper Networks
Differential Revision: https://reviews.freebsd.org//D23827

Fix comment parsing in interp_simple.c

loader.rc has comment lines without a trailing space, which get
interpreted as commands. Avoid this by only matching against the
backslash character.

Reviewed by: imp, tsoome
Differential Revision: https://reviews.freebsd.org/D20491

Enable veriexec for loader

This relies on libbearssl and libsecureboot
to verify files read by loader in a maner equivalent
to how mac_veriexec

Note: disabled by default.
Use is initially expected to be by embeded vendors

Reviewed by: emaste, imp
Sponsored by: Juniper Networks
Differential Revision: D16336

userboot: handle guest interpreter mismatches more intelligently

The switch to lualoader creates a problem with userboot: the host is
inclined to build userboot with Lua, but the host userboot's interpreter
must match what's available on the guest. For almost all FreeBSD guests in
the wild, Lua is not yet available and a Lua-based userboot will fail.

This revision updates userboot protocol to version 5, which adds a
swap_interpreter callback to request a different interpreter, and tries to
determine the proper interpreter to be used based on how the guest
/boot/loader is compiled. This is still a bit of a guess, but it's likely
the best possible guess we can make in order to get it right. The
interpreter is now embedded in the resulting executable, so we can open
/boot/loader on the guest and hunt that down to derive the interpreter it
was built with.

Using -l with bhyveload will not allow an intepreter swap, even if the
loader specified happens to be a userboot with the wrong interpreter. We'll
simply complain about the mismatch and bail out.

For legacy guests without the interpreter marker, we assume they're 4th.
For new guests with the interpreter marker, we'll read it and swap over
to the proper interpreter if it doesn't match what the userboot we're using
was compiled with.

Both flavors of userboot are installed by default, userboot_4th.so and
userboot_lua.so. This fixes the build WITHOUT_FORTH as a coincidence, which
was broken by userboot being forced to 4th.

Reviewed by: imp, jhb, araujo (earlier version)
Approved by: re (gjb)
Differential Revision: https://reviews.freebsd.org/D16945

Set script.lang in the environment to either 'forth' or 'simple' to
reflect what scripting language was compiled into the loader. I
anticipate that being able to find this out quickly from the OK prompt
will be useful in troubleshooting in the future.

Move simple interpreter 'perform' into interp.c and call it
interp_builtin_cmd().

Fix indentation to FreeBSD standard for interp files

Break out the interpreters (simple and forth) w/o ifdefs. This is
akin to what Pedro Souza and Wojciech Koszek did in the lua GSoC with
interp.h, interp_simple.c and changes to interp.c and interp_forth.c,
but completely redone from scratch.

This effectively restores the spirit of r326712 (my first attempt to
bring in Pedro's and Wojciech's work) updated for new requirements
that had silently broke their original work. This change also differs
by using fixed function names instead of function pointers to simply
things. Only one interpreter at a time may be compiled in.

Also of note: we take a mutable string, pass it in via a const char *
pointer into intrp_forth's interp_run(). We then cast away the const
to pass into ficlExec since ficl would require extensive changes to
properly const-poison. See Sections 6.5.2.5 and 6.7.3 of C11 standard
noting it's only UB if you modify a const object through a non-const
pointer, but not char [] -> const char * -> char * as here.

Revert r326792, r326784, r326772, r326712

Something subtle is creating problems for disk access on ubldr. Back
it out unti that can be sorted out.

Sponsored by: Netflix

Create interp class.

Create an interp class. Use it to separate out the different types of
interpreters: forth and simple with function pointers rather than
via #ifdefs.

Obtained from: lua boot loader project
(via https://bsdimp@github.com/bsdimp/freebsd.git lua-bootloader)
Sponsored by: Netflix