linux(4): Update my copyrights, add SPDX tag

sys: Remove $FreeBSD$: two-line .h pattern

Remove /^\s*\*\n \*\s+\$FreeBSD\$$\n/

linux(4): Uniformly dev_t arguments translation

The two main uses of dev_t are in struct stat and as a parameter of the
mknod system calls.
As of version 2.6.0 of the Linux kernel, dev_t is a 32-bit quantity
with 12 bits set asaid for the major number and 20 for the minor number.
The in-kernel dev_t encoded as MMMmmmmm, where M is a hex digit of the
major number and m is a hex digit of the minor number.
The user-space dev_t encoded as mmmM MMmm, where M and m is the major
and minor numbers accordingly. This is downward compatible with legacy
systems where dev_t is 16 bits wide, encoded as MMmm.
In glibc dev_t is a 64-bit quantity, with 32-bit major and minor numbers,
encoded as MMMM Mmmm mmmM MMmm. This is downward compatible with the Linux
kernel and with legacy systems where dev_t is 16 bits wide.
In the FreeBSD dev_t is a 64-bit quantity. The major and minor numbers
are encoded as MMMmmmMm, therefore conversion of the device numbers between
Linux user-space and FreeBSD kernel required.

linux(4): Move dev_t type declaration under /compat/linux

As of version 2.6.0 of the Linux kernel, dev_t is a 32-bit unsigned integer
on all platforms. Move it into the MI linux.h under /compat/linux.

linux(4): Migrate to IfAPI

Migrate linux and linprocfs to use the IfAPI interfaces instead of
direct ifnet accesses.
The code initially writed by jhibbits@, and adapted by me to 3ab3c9c2.

Reviewed by: jhibbits
Differential Revision: https://reviews.freebsd.org/D38735

Revert "Port Linuxulator to IfAPI"

Revert pending netlink fixes, and further fixes to this.

This reverts commit 52d984831d82d97dc132d0d57fca6ee89572799b.

Requested by: dchagin

Port Linuxulator to IfAPI

Reviewed by: dchagin
Sponsored by: Juniper Networks, Inc.
Differential Revision: https://reviews.freebsd.org/D38349

linux(4): Move use_real_names knob to the linux.c

MI linux.[c|h] are the module independent in terms of the Linux emulation
layer (ie, intended for both ISA - 32 & 64 bit), analogue of MD linux.h.
There must be a code here that cannot be placed into the corresponding by
common sense MI source and header files, i.e., code is machine independent,
but ISA dependent.
For the use_real_names knob, the code must be placed into the
linux_socket.[c|h], however linux_socket is ISA dependent.

MFC after: 2 weeks

linux(4): Cleanup sys/queue.h from linux.h

Leftover after converting futexes to the umtx API.

NFC after: 2 weeks

linux(4): Convert mount exported flags for statfs system calls.

MFC after: 1 week

linuxolator: add netlink support

Add the glue code to support netlink in Linuxolator.
linux_common(4) now depends on netlink(4).

All netlink protocol constants are consistent with the Linux version.
However, certain OS-specific constants such as AF_INET6, interface
flags or default routing table id, are different between FreeBSD and
Linux. Thus, it may be needed to rewrite some message parts or even
rewrite the whole message, adding or removing some TLVs. The core
netlink implementation code provides efficient rewriting callbacks
which Linuxolator now uses.

Reviewed by: dchagin
Differential Revision: https://reviews.freebsd.org/D36361
MFC after: 2 months

linux(4): Trace Linux l_sigset_t.

MFC after: 2 weeks

linux(4): Fix the type of a constant in the signal mask macro

Since l_sigset_t is 64-bit unsigned on all Linuxulators, fix the type
of a constant in the signal mask manipulation macro.
The suffix L indicates type long which is 32-bit on i386, therefore,
bitwise operations between a 32-bit constant and 64-bit signal mask
lead to the wrong result.

Pointy hat to: dchagin
MFC after: 2 weeks

linux(4): Reduce duplication between MD parts of the Linuxulator

Move sigprocmask actions defines under compat/linux,
they are identical across all Linux architectures.

MFC after: 2 weeks

linux: add sysctl to pass untranslated interface names

Reviewed by: kib
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D33792

linux(4): Add struct clone_args for future clone3 system call.

In preparation for clone3 system call add struct clone_args and use it in
clone implementation.
Move all of clone related bits to the newly created linux_fork.h header.

Differential revision: https://reviews.freebsd.org/D31474
MFC after: 2 weeks

linux(4): Reimplement futexes using umtx.

Differential Revision: https://reviews.freebsd.org/D31236
MFC after: 2 weeks

linux(4): Allow musl brand to use FUTEX_REQUEUE op.

Initial patch from submitter was adapted by me to prevent unconditional
FUTEX_REQUEUE use.

PR: 255947
Submitted by: Philippe Michaud-Boudreault
Differential Revision: https://reviews.freebsd.org/D30332

Drop "All rights reserved" from my copyright statements.

Add email and fixup years while here.

Reviewed by: imp
Differential Revision: https://reviews.freebsd.org/D30912
MFC after: 2 weeks

linux(4): Rework Linux ppoll system call.

For now the Linux emulation layer uses in kernel ppoll(2) without
conversion of user supplied fd 'events', and does not convert the
kernel supplied fd 'revents'.

At least POLLRDHUP is handled by FreeBSD differently than by
Linux. Seems that Linux silencly ignores POLLRDHUP on non socket fd's
unlike FreeBSD, which does more strictly check and fails.

Rework the Linux ppoll, using kern_poll and converting 'events'
and 'revents' values.
While here, move poll events defines to the MI part of code as they
mostly identical on all arches except arm.

Differential Revision: https://reviews.freebsd.org/D30716
MFC after: 2 weeks

linux: implement statx(2)

PR: 252106
Reviewed By: dchagin
Differential Revision: https://reviews.freebsd.org/D30466

linux(4): Improve netlink diagnostics

Add some missing netlink_family definitions and produce vaguely
human-readable error messages for those definitions, like we used to do for
just ROUTE and KOBJECT_UEVENTS.

Additionally, if we know it's a netfilter socket but didn't find it in the
table, fall back to printing that instead of the generic handler ("socket
domain 16, ...").

No change to the emulator correctness, just mildly improved diagnostics for
gaps.

Add defines for Linux errno values and use them to make linux_errtbl[]
more readable. While here, add linux_check_errtbl() function to make
sure we don't leave holes.

No objections: emaste (earlier version)
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D26972

Fix misnomer - linux_to_bsd_errno() does the exact opposite.

Reported by: arichardson
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D26965

Tweak linux(4) socket(2) debug messages.

MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D26900

Get rid of sv_errtbl and SV_ABI_ERRNO().

Reviewed by: kib
Sponsored by: DARPA
Differential Revision: https://reviews.freebsd.org/D26388

linux: reposition the comment for bsd_to_linux_bits/linux_to_bsd_bits

rpokala notes that splitting the definitions like this is kind of silly,
since the comment applies to both. Move the comment up (or the definition
down, depending on your perspective on life) accordingly.

Reported by: rpokala

linuxolator: implement memfd_create syscall

This effectively mirrors our libc implementation, but with minor fudging --
name needs to be copied in from userspace, so we just copy it straight into
stack-allocated memfd_name into the correct position rather than allocating
memory that needs to be cleaned up.

The sealing-related fcntl(2) commands, F_GET_SEALS and F_ADD_SEALS, have
also been implemented now that we support them.

Note that this implementation is still not quite at feature parity w.r.t.
the actual Linux version; some caveats, from my foggy memory:

- Need to implement SHM_GROW_ON_WRITE, default for memfd (in progress)
- LTP wants the memfd name exposed to fdescfs
- Linux allows open() of an fdescfs fd with O_TRUNC to truncate after dup.
(?)

Interested parties can install and run LTP from ports (devel/linux-ltp) to
confirm any fixes.

PR: 240874
Reviewed by: kib, trasz
Differential Revision: https://reviews.freebsd.org/D21845

compat/linux/linux.h depends on queue.h since r353725.

Sponsored by: The FreeBSD Foundation

Make linux(4) create /dev/shm. Linux applications often expect
a tmpfs to be mounted there, and because they like to verify it's
actually a mountpoint, a symlink won't do.

Reviewed by: dchagin (earlier version)
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D20333

linux: futex_mtx should follow futex_list

Move futex_mtx to linux_common.ko for amd64 and aarch64 along
with respective list/mutex init/destroy.

PR: 240989
Reported by: Alex S <iwtcex@gmail.com>

linux: provide just one instance of futex_list

Move futex_list definition to linux.c which is included once
in linux.ko (i386) and in linux_common.ko (amd64 and aarch64)
allowing 32/64 bit linux programs to access the same futexes
in the latter case.

PR: 240989
Reviewed by: dchagin
Differential Revision: https://reviews.freebsd.org/D22073

Our bsd_to_linux_sockaddr() and linux_to_bsd_sockaddr() functions
alter the userspace sockaddr to convert the format between linux and BSD versions.
That's the minimum 3 of copyin/copyout operations for one syscall.

Also some syscall uses linux_sa_put() and linux_getsockaddr() when load
sockaddr to userspace or from userspace accordingly.

To avoid this chaos, especially converting sockaddr in the userspace,
rewrite these 4 functions to convert sockaddr only in kernel and leave
only 2 of this functions.

Also in order to reduce duplication between MD parts of the Linuxulator put
struct sockaddr conversion functions that are MI out into linux_common module.

PR: 232920
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D20157

Rewrite linux_ifflags() in more readable Linuxulator style.

Reviewed by: emaste
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D20146

In order to reduce duplication between MD parts of the Linuxulator
move bits that are MI out into the headers in compat/linux.
For that remove bogus _packed attribute from struct l_sockaddr
and use MI types for struct members.

And continue to move into the linux_common module a code that is
intended for both Linuxulator modules (both instruction set - 32 & 64 bit)
or for external modules like linsysfs or linprocfs.

To avoid header pollution introduce new sys/compat/linux_common.h header.

Reviewed by: emaste
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D20137

Rework signal code to allow using it by other modules, like linprocfs:

1. Linux sigset always 64 bit on all platforms. In order to move Linux
sigset code to the linux_common module define it as 64 bit int. Move
Linux sigset manipulation routines to the MI path.

2. Move Linux signal number definitions to the MI path. In general, they
are the same on all platforms except for a few signals.

3. Map Linux RT signals to the FreeBSD RT signals and hide signal conversion
tables to avoid conversion errors.

4. Emulate Linux SIGPWR signal via FreeBSD SIGRTMIN signal which is outside
of allowed on Linux signal numbers.

PR: 197216