y2038: Add time64 system calls

This series finally gets us to the point of having system calls with
64-bit time_t on all architectures, after a long time of incremental
preparation patches.

There was actually one conversion that I missed during the summer,
i.e. Deepa's timex series, which I now updated based the 5.0-rc1 changes
and review comments.

The following system calls are now added on all 32-bit architectures
using the same system call numbers:

403 clock_gettime64
404 clock_settime64
405 clock_adjtime64
406 clock_getres_time64
407 clock_nanosleep_time64
408 timer_gettime64
409 timer_settime64
410 timerfd_gettime64
411 timerfd_settime64
412 utimensat_time64
413 pselect6_time64
414 ppoll_time64
416 io_pgetevents_time64
417 recvmmsg_time64
418 mq_timedsend_time64
419 mq_timedreceiv_time64
420 semtimedop_time64
421 rt_sigtimedwait_time64
422 futex_time64
423 sched_rr_get_interval_time64

Each one of these corresponds directly to an existing system call
that includes a 'struct timespec' argument, or a structure containing
a timespec or (in case of clock_adjtime) timeval. Not included here
are new versions of getitimer/setitimer and getrusage/waitid, which
are planned for the future but only needed to make a consistent API
rather than for correct operation beyond y2038. These four system
calls are based on 'timeval', and it has not been finally decided
what the replacement kernel interface will use instead.

So far, I have done a lot of build testing across most architectures,
which has found a number of bugs. Runtime testing so far included
testing LTP on 32-bit ARM with the existing system calls, to ensure
we do not regress for existing binaries, and a test with a 32-bit
x86 build of LTP against a modified version of the musl C library
that has been adapted to the new system call interface [3].
This library can be used for testing on all architectures supported
by musl-1.1.21, but it is not how the support is getting integrated
into the official musl release. Official musl support is planned
but will require more invasive changes to the library.

Link: https://lore.kernel.org/lkml/20190110162435.309262-1-arnd@arndb.de/T/
Link: https://lore.kernel.org/lkml/20190118161835.2259170-1-arnd@arndb.de/
Link: https://git.linaro.org/people/arnd/musl-y2038.git/ [2]
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
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y2038: add 64-bit time_t syscalls to all 32-bit architectures

This adds 21 new system calls on each ABI that has 32-bit time_t
today. All of these have the exact same semantics as their existing
counterparts, and the new ones all have macro names that end in 'time64'
for clarification.

This gets us to the point of being able to safely use a C library
that has 64-bit time_t in user space. There are still a couple of
loose ends to tie up in various areas of the code, but this is the
big one, and should be entirely uncontroversial at this point.

In particular, there are four system calls (getitimer, setitimer,
waitid, and getrusage) that don't have a 64-bit counterpart yet,
but these can all be safely implemented in the C library by wrapping
around the existing system calls because the 32-bit time_t they
pass only counts elapsed time, not time since the epoch. They
will be dealt with later.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
19 files changed