the syscall numbers were reserved in v5.3 but not wired up on mips, see

  linux commit 0671c5b84e9e0a6d42d22da9b5d093787ac1c5f3
  MIPS: Wire up clone3 syscall

see

  linux commit 7615d9e1780e26e0178c93c55b73309a5dc093d7
  arch: wire-up pidfd_open()

  linux commit 32fcb426ec001cb6d5a4a195091a8486ea77e2df
  pid: add pidfd_open()

now that all 32-bit archs have 64-bit time_t (and suseconds_t), the
arch-provided _Int64 macro (long or long long, as appropriate) can be
used to define them, and arch-specific definitions are no longer
needed.

these structures can now be defined generically in terms of endianness
and long size. previously, the 32-bit archs all shared a common
definition from the generic bits header, and each 64-bit arch had to
repeat the 64-bit version, with endian conditionals if the arch had
variants of each endianness.

I would prefer getting rid of the preprocessor conditionals for
padding and instead using unnamed bitfield members, like commit
9b2921be did for struct timespec.
however, at present sendmsg, recvmsg, and recvmmsg need access to the
padding members by name to zero them. this could perhaps be cleaned up
in the future.

policy has long been that these definitions are purely a function of
whether long/pointer is 32- or 64-bit, and that they are not allowed
to vary per-arch. move the definition to the shared alltypes.h.in
fragment, using integer constant expressions in terms of sizeof to
vary the array dimensions appropriately. I'm not sure whether this is
more or less ugly than using preprocessor conditionals and two sets of
definitions here, but either way is a lot less ugly than repeating the
same thing for every arch.

LLONG_MAX is uniform for all archs we support and plenty of header and
code level logic assumes it is, so it does not make sense for limits.h
bits mechanism to pretend it's variable.

LONG_BIT can be defined in terms of LONG_MAX; there's no reason to put
it in bits.

by moving LONG_MAX definition to __LONG_MAX in alltypes.h and moving
LLONG_MAX out of bits, there are now no plain-C limits that are
defined in the bits header, so the bits header only needs to be
included in the POSIX or extended profiles. this allows the feature
test macro logic to be removed from the bits header, facilitating a
long-term goal of getting such logic out of bits.

having __LONG_MAX in alltypes.h will allow further generalization of
headers.

archs without a constant PAGESIZE no longer need bits/limits.h at all.

building on commit 97d35a55,
__BYTE_ORDER is now available wherever alltypes.h is included.
endian.h should not be used since, in the future, it will expose
identifiers that are not in the reserved namespace for the headers
which were previously using it.

this change is motivated by the intersection of several factors.
presently, despite being a nonstandard header, endian.h is exposing
the unprefixed byte order macros and functions only if _BSD_SOURCE or
_GNU_SOURCE is defined. this is to accommodate use of endian.h from
other headers, including bits headers, which need to define structure
layout in terms of endianness. with time64 switch-over, even more
headers will need to do this.

at the same time, the resolution of Austin Group issue 162 makes
endian.h a standard header for POSIX-future, requiring that it expose
the unprefixed macros and the functions even in standards-conforming
profiles. changes to meet this new requirement would break existing
internal usage of endian.h by causing it to violate namespace where
it's used.

instead, have the arch's alltypes.h define __BYTE_ORDER, either as a
fixed constant or depending on the right arch-specific predefined
macros for determining endianness. explicit literals 1234 and 4321 are
used instead of __LITTLE_ENDIAN and __BIG_ENDIAN so that there's no
danger of getting the wrong result if a macro is undefined and
implicitly evaluates to 0 at the preprocessor level.

the powerpc (32-bit) bits/endian.h being removed had logic for varying
endianness, but our powerpc arch has never supported that and has
always been big-endian-only. this logic is not carried over to the new
__BYTE_ORDER definition in alltypes.h.

now that commit f7f10797 removed the
legacy i386 conditional definition, va_list is in no way
arch-specific, and has no reason to be in the future. move it to the
shared part of alltypes.h.in

new mount api syscalls were added, same numers on all targets, see

  linux commit a07b20004793d8926f78d63eb5980559f7813404
  vfs: syscall: Add open_tree(2) to reference or clone a mount

  linux commit 2db154b3ea8e14b04fee23e3fdfd5e9d17fbc6ae
  vfs: syscall: Add move_mount(2) to move mounts around

  linux commit 24dcb3d90a1f67fe08c68a004af37df059d74005
  vfs: syscall: Add fsopen() to prepare for superblock creation

  linux commit ecdab150fddb42fe6a739335257949220033b782
  vfs: syscall: Add fsconfig() for configuring and managing a context

  linux commit 93766fbd2696c2c4453dd8e1070977e9cd4e6b6d
  vfs: syscall: Add fsmount() to create a mount for a superblock

  linux commit cf3cba4a429be43e5527a3f78859b1bfd9ebc5fb
  vfs: syscall: Add fspick() to select a superblock for reconfiguration

  linux commit 9c8ad7a2ff0bfe58f019ec0abc1fb965114dde7d
  uapi, x86: Fix the syscall numbering of the mount API syscalls [ver #2]

  linux commit d8076bdb56af5e5918376cd1573a6b0007fc1a89
  uapi: Wire up the mount API syscalls on non-x86 arches [ver #2]

the definition of the IPC_64 macro controls the interface between libc
and the kernel through syscalls; it's not a public API. the meaning is
rather obscure. long ago, Linux's sysvipc *id_ds structures used
16-bit uids/gids and wrong types for a few other fields. this was in
the libc5 era, before glibc. the IPC_64 flag (64 is a misnomer; it's
more like 32) tells the kernel to use the modern[-ish] versions of the
structures.

the definition of IPC_64 has nothing to do with whether the arch is
32- or 64-bit. rather, due to either historical accident or
intentional obnoxiousness, the kernel only accepts and masks off the
0x100 IPC_64 flag conditional on CONFIG_ARCH_WANT_IPC_PARSE_VERSION,
i.e. for archs that want to provide, or that accidentally provided,
both. for archs which don't define this option, no masking is
performed and commands with the 0x100 bit set will fail as invalid. so
ultimately, the definition is just a matter of matching an arbitrary
switch defined per-arch in the kernel.

some of these were not exact duplicates, but had gratuitously
different naming for padding, or omitted the endian checks because the
arch is fixed-endian.

various padding fields in the generic bits/sem.h were defined in terms
of time_t as a cheap hack standing in for "kernel long", to allow x32
to use the generic version of the file. this was a really bad idea, as
it ended up getting copied into lots of arch-specific versions of the
bits file, and is a blocker to changing time_t to 64-bit on 32-bit
archs.

this commit adds an x32-specific version of the header, and changes
padding type back from time_t to long (currently the same type on all
archs but x32) in the generic header and all the others the hack got
copied into.

these were overlooked during review. bits headers are not allowed to
pull in additional headers (note: that rule is currently broken in
other places but just for endian.h). string.h has no place here
anyway, and including bits/alltypes.h without defining macros to
request types from it is a nop.

Commit 3517d74a changed the token in
sys/ioctl.h from 0x01 to 1, so bits/termios.h no longer matches. Revert
the bits/termios.h change to keep the headers in sync.

This reverts commit 9eda4dc6.

syscall numbers are now synced up across targets (starting from 403 the
numbers are the same on all targets other than an arch specific offset)

IPC syscalls sem*, shm*, msg* got added where they were missing (except
for semop: only semtimedop got added), the new semctl, shmctl, msgctl
imply IPC_64, see

  linux commit 0d6040d4681735dfc47565de288525de405a5c99
  arch: add split IPC system calls where needed

new 64bit time_t syscall variants got added on 32bit targets, see

  linux commit 48166e6ea47d23984f0b481ca199250e1ce0730a
  y2038: add 64-bit time_t syscalls to all 32-bit architectures

new async io syscalls got added, see

  linux commit 2b188cc1bb857a9d4701ae59aa7768b5124e262e
  Add io_uring IO interface

  linux commit edafccee56ff31678a091ddb7219aba9b28bc3cb
  io_uring: add support for pre-mapped user IO buffers

a new syscall got added that uses the fd of /proc/<pid> as a stable
handle for processes: allows sending signals without pid reuse issues,
intended to eventually replace rt_sigqueueinfo, kill, tgkill and
rt_tgsigqueueinfo, see

  linux commit 3eb39f47934f9d5a3027fe00d906a45fe3a15fad
  signal: add pidfd_send_signal() syscall

on some targets (arm, m68k, s390x, sh) some previously missing syscall
numbers got added as well.

the numbers added in

  commit d149e69c
  add io_pgetevents and rseq syscall numbers from linux v4.18

were incorrect.

io_pgetevents is new in linux commit
7a074e96dee62586c935c80cecd931431bfdd0be

rseq is new in linux commit
d7822b1e24f2df5df98c76f0e94a5416349ff759

sys/ptrace.h is target specific, use bits/ptrace.h to add target
specific macro definitions.

these macros are kept in the generic sys/ptrace.h even though some
targets don't support them:

PTRACE_GETREGS
PTRACE_SETREGS
PTRACE_GETFPREGS
PTRACE_SETFPREGS
PTRACE_GETFPXREGS
PTRACE_SETFPXREGS

so no macro definition got removed in this patch on any target. only
s390x has a numerically conflicting macro definition (PTRACE_SINGLEBLOCK).

the PT_ aliases follow glibc headers, otherwise the definitions come
from linux uapi headers except ones that are skipped in glibc and
there is no real kernel support (s390x PTRACE_*_AREA) or need special
type definitions (mips PTRACE_*_WATCH_*) or only relevant for linux
2.4 compatibility (PTRACE_OLDSETOPTIONS).

adapted from patch by Matthias Schiffer.

new in linux commit 256211f2b0b251e532d1899b115e374feb16fa7a

the output delay features (NL*, CR*, TAB*, BS*, and VT*) are
XSI-shaded. VT* is in the V* namespace reservation but the rest need
to be suppressed in base POSIX namespace.

unfortunately this change introduces feature test macro checks into
another bits header. at some point these checks should be simplified
by having features.h handle the "FTM X implies Y" relationships.

for synchronous page faults, new in linux commit
1c9725974074a047f6080eecc62c50a8e840d050 and
b6fb293f2497a9841d94f6b57bd2bb2cd222da43
note that only targets that use asm-generic/mman.h have this new
flag defined, so undef it on other targets (mips*, powerpc*).

use the same token to define TIOCSER_TEMT as is used in ioctl.h
so when both headers are included there are no redefinition warnings
during musl build.

added for safe opening of peer end of pty in a mount namespace.
new in linux commit c6325179238f1d4683edbec53d8322575d76d7e2

statx was added in linux commit a528d35e8bfcc521d7cb70aaf03e1bd296c8493f
(there is no libc wrapper yet and microblaze and sh misses the number).

it is defined in linux asm/sockios.h since commit
ae40eb1ef30ab4120bd3c8b7e3da99ee53d27a23 (linux v2.6.22)
but was missing from musl by accident.

in musl the sockios macros are exposed in sys/ioctl.h together
with other ioctl requests instead of in sys/socket.h because of
namespace rules. (glibc has them in sys/socket.h under _GNU_SOURCE.)

see linux commit e8c24d3a23a469f1f40d4de24d872ca7023ced0a
and linux Documentation/x86/protection-keys.txt

aarch64, arm, mips, mips64, mipsn32, powerpc, powerpc64 and sh have
cpu feature bits defined in linux for AT_HWCAP auxv entry, so expose
those in sys/auxv.h

it seems the mips hwcaps were never exposed to userspace neither
by linux nor by glibc, but that's most likely an oversight.

revert commit 8c316e9e. it was wrong
and does not match how the kernel API works.

these were incorrectly using the generic definitions.

same changes to the defined macros as in powerpc and generic bits.

it seems it was a typo.

TIOCM_ macros were wrongly using the asm-generic/termios.h definitions
instead of the mips specific ones from asm/termios.h

mips and powerpc use their own asm/ioctls.h, not the asm-generic/ioctls.h
and they lack termiox macros that are available on other targets.
see kernel commit 1d65b4a088de407e99714fdc27862449db04fb5c