MFC r359937:

Centralize compatability translation macros.

Copy the CP, PTRIN, etc macros from freebsd32.h into a sys/abi_compat.h
and replace existing definitation with includes where required. This
eliminates duplicate code and allows Linux and FreeBSD compatability
headers to be included in the same files.

Obtained from: CheriBSD
Sponsored by: DARPA
Differential Revision: https://reviews.freebsd.org/D24275

MFC r345471, r345472, r346603:

Update syscall.master to 5.0.

For 32-bit Linuxulator, ipc() syscall was historically
the entry point for the IPC API. Starting in Linux 4.18, direct
syscalls are provided for the IPC. Enable it.

MFC r335201 (by emaste@):

linuxulator: do not include legacy syscalls on arm64

Existing linuxulator platforms (i386, amd64) support legacy syscalls,
such as non-*at ones like open, but arm64 and other new platforms do
not.

Wrap these in #ifdef LINUX_LEGACY_SYSCALLS, #defined in the MD linux.h
files. We may need finer grained control in the future but this is
sufficient for now.

MFC r331226 (byu emaste@):

Rename linuxulator functions with linux_ prefix

It's preferable to have a consistent prefix. This also reduces
differences between the three linux*_sysvec.c files.

MFC r328890 (by emaste@):

Linuxolator whitespace cleanup

A version of each of the MD files by necessity exists for each CPU
architecture supported by the Linuxolator. Clean these up so that new
architectures do not inherit whitespace issues.

Clean up shared Linuxolator files while here.

Revert r330897:

This was intended to be a non-functional change. It wasn't. The commit
message was thus wrong. In addition it broke arm, and merged crypto
related code.

Revert with prejudice.

This revert skips files touched in r316370 since that commit was since
MFCed. This revert also skips files that require $FreeBSD$ property
changes.

Thank you to those who helped me get out of this mess including but not
limited to gonzo, kevans, rgrimes.

Requested by: gjb (re)

MFC r331234: Rationalize license text on Linuxolator files

i386 linux.h missed in previous update.

Approved by: sos
Sponsored by: The FreeBSD Foundation

Partial merge of the SPDX changes

These changes are incomplete but are making it difficult
to determine what other changes can/should be merged.

No objections from: pfg

MFC r315501:

To reduce code duplication move socket defines to the MI path.

MFC r314866:

Reduce code duplication between MD Linux code by moving SYSV IPC 64-bit
related struct definitions out into the MI path.

Invert the native ipc structs to the Linux ipc structs convesion logic.
Since 64-bit variant of ipc structs has more precision convert native ipc
structs to the 64-bit Linux ipc structs and then truncate 64-bit values
into the non 64-bit if needed. Unlike Linux, return EOVERFLOW if the
values do not fit.

Fix SYSV IPC for 64-bit Linuxulator which never sets IPC_64 bit.

MFC 316644:

Trying to be more compatible with Linux if.h definitions:
- renaming l_ifreq::ifru_metric to l_ifreq::ifru_ivalue;
- adding a definition for ifr_ifindex which points to l_ifreq::ifru_ivalue.

A quick search indicates that Linux already got the above changes since 2.1.14.

Reviewed by: kib, marcel, dchagin

MFC r314282:

Fix linux_fstatfs() to return proper value for f_frsize. Without it,
linux df(1) binary from Xenial shows garbage.

MFC r302517:

Fix a copy/paste bug introduced during X86_64 Linuxulator work.
FreeBSD support NX bit on X86_64 processors out of the box, for i386 emulation
use READ_IMPLIES_EXEC flag, introduced in r302515.

While here move common part of mmap() and mprotect() code to the files in compat/linux
to reduce code dupcliation between Linuxulator's

Approved by: re (gjb)