without this, the SO_RCVTIMEO and SO_SNDTIMEO socket options would
stop working on pre-5.1 kernels after time_t is switched to 64-bit and
their values are changed to the new time64 versions.

new code is written such that it's statically unreachable on 64-bit
archs, and on existing 32-bit archs until the macro values are changed
to activate 64-bit time_t.

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.

now that we have a kstat structure decoupled from the public struct
stat, we can just use the broken kernel structures directly and let
the code in fstatat do the translation.

presently, all archs/ABIs have struct stat matching the kernel
stat[64] type, except mips/mipsn32/mips64 which do conversion hacks in
syscall_arch.h to work around bugs in the kernel type. this patch
completely decouples them and adds a translation step to the success
path of fstatat. at present, this is just a gratuitous copying, but it
opens up multiple possibilities for future support for 64-bit time_t
on 32-bit archs and for cleaned-up/unified ABIs.

for clarity, the mips hacks are not yet removed in this commit, so the
mips kstat structs still correspond to the output of the hacks in
their syscall_arch.h files, not the raw kernel type. a subsequent
commit will fix this.

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.

ever since inline syscalls were added for (o32) mips in commit
328810d3, the asm has nonsensically
loaded the syscall number, rather than taking $2 as an input
constraint to let the compiler load it. commit
cfc09b1e improved on this somewhat by
allowing a constant syscall number to propagate into an immediate, but
missed that the whole operation made no sense.

now, only $4, $5, $6, $8, and $9 are potential input-only registers.
$2 is always input and output, and $7 is both when it's an argument,
otherwise output-only. previously, $7 was treated as an input (with a
"1" constraint matching its output position) even when it was not an
input, which was arguably undefined behavior (asm input from
indeterminate value). this is corrected.

this patch is not purely non-functional changes, since before, $8 and
$9 were wrongly in the clobberlist for syscalls with fewer than 5 or 6
arguments. of course it's impossible for syscalls to have different
clobbers depending on their number of arguments. the clobberlist for
the recently-added 5- and 6-argument forms was correct, and for the 0-
to 4-argument forms was erroneously copied from the mips o32 ABI where
the additional arguments had to be passed on the stack.

in making this change, I reviewed the kernel sources, and $8 and $9
are always saved for 64-bit kernels since they're part of the syscall
argument list for n32 and n64 ABIs.

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.

n32 and n64 ABIs add new argument registers vs o32, so that passing on
the stack is not necessary, so it's not clear why the 5- and
6-argument versions were special-cased to begin with; it seems to have
been pattern-copying from arch/mips (o32).

i've treated the new argument registers like the first 4 in terms of
clobber status (non-clobbered). hopefully this is correct.

io_pgetevents is new in linux commit
7a074e96dee62586c935c80cecd931431bfdd0be

rseq is new in linux commit
d7822b1e24f2df5df98c76f0e94a5416349ff759

this will allow the compiler to cache and reuse the result, meaning we
no longer have to take care not to load it more than once for the sake
of archs where the load may be expensive.

depends on commit 1c84c999 for
correctness, since otherwise the compiler could hoist loads during
stage 3 of dynamic linking before the initial thread-pointer setup.

these were overlooked in the declarations overhaul work because they
are not properly declared, and the current framework even allows their
declared types to vary by arch. at some point this should be cleaned
up, but I'm not sure what the right way would be.

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

In TLS variant I the TLS is above TP (or above a fixed offset from TP)
but on some targets there is a reserved gap above TP before TLS starts.

This matters for the local-exec tls access model when the offsets of
TLS variables from the TP are hard coded by the linker into the
executable, so the libc must compute these offsets the same way as the
linker.  The tls offset of the main module has to be

	alignup(GAP_ABOVE_TP, main_tls_align).

If there is no TLS in the main module then the gap can be ignored
since musl does not use it and the tls access models of shared
libraries are not affected.

The previous setup only worked if (tls_align & -GAP_ABOVE_TP) == 0
(i.e. TLS did not require large alignment) because the gap was
treated as a fixed offset from TP.  Now the TP points at the end
of the pthread struct (which is aligned) and there is a gap above
it (which may also need alignment).

The fix required changing TP_ADJ and __pthread_self on affected
targets (aarch64, arm and sh) and in the tlsdesc asm the offset to
access the dtv changed too.

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.)

at one point, clang reportedly failed to support the asm register
constraints needed for inline syscalls. versions of clang that old
have much bigger problems that preclude using them to compile musl
libc.

mips64 requires 'struct stat' conversion due to incorrect 32-bit
fields where time_t should be in the kernel version of the structure.
syscall_arch.h already performed the correct translation for stat,
fstat, and lstat syscalls, but omitted special handling for fstatat.

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