y2038: core, driver and file system changes

These are updates to device drivers and file systems that for some reason
or another were not included in the kernel in the previous y2038 series.

I've gone through all users of time_t again to make sure the kernel is
in a long-term maintainable state, replacing all remaining references
to time_t with safe alternatives.

Some related parts of the series were picked up into the nfsd, xfs,
alsa and v4l2 trees. A final set of patches in linux-mm removes the now
unused time_t/timeval/timespec types and helper functions after all five
branches are merged for linux-5.6, ensuring that no new users get merged.

As a result, linux-5.6, or my backport of the patches to 5.4 [1], should
be the first release that can serve as a base for a 32-bit system designed
to run beyond year 2038, with a few remaining caveats:

- All user space must be compiled with a 64-bit time_t, which will be
  supported in the coming musl-1.2 and glibc-2.32 releases, along with
  installed kernel headers from linux-5.6 or higher.

- Applications that use the system call interfaces directly need to be
  ported to use the time64 syscalls added in linux-5.1 in place of the
  existing system calls. This impacts most users of futex() and seccomp()
  as well as programming languages that have their own runtime environment
  not based on libc.

- Applications that use a private copy of kernel uapi header files or
  their contents may need to update to the linux-5.6 version, in
  particular for sound/asound.h, xfs/xfs_fs.h, linux/input.h,
  linux/elfcore.h, linux/sockios.h, linux/timex.h and linux/can/bcm.h.

- A few remaining interfaces cannot be changed to pass a 64-bit time_t
  in a compatible way, so they must be configured to use CLOCK_MONOTONIC
  times or (with a y2106 problem) unsigned 32-bit timestamps. Most
  importantly this impacts all users of 'struct input_event'.

- All y2038 problems that are present on 64-bit machines also apply to
  32-bit machines. In particular this affects file systems with on-disk
  timestamps using signed 32-bit seconds: ext4 with ext3-style small
  inodes, ext2, xfs (to be fixed soon) and ufs.

Changes since v1 [2]:

- Add Acks I received
- Rebase to v5.5-rc1, dropping patches that got merged already
- Add NFS, XFS and the final three patches from another series
- Rewrite etnaviv patches
- Add one late revert to avoid an etnaviv regression

[1] https://git.kernel.org/pub/scm/linux/kernel/git/arnd/playground.git/log/?h=y2038-endgame
[2] https://lore.kernel.org/lkml/20191108213257.3097633-1-arnd@arndb.de/
Revert "drm/etnaviv: reject timeouts with tv_nsec >= NSEC_PER_SEC"

This reverts commit 245595e83fbedda9e107eb0b37cec0ad07733778.

Guido Günther reported issues with this patch that broke existing
user space. Let's revert it for now and fix it properly later on.

Link: https://patchwork.kernel.org/patch/11291089/
https://lore.kernel.org/lkml/20200121114553.2667556-1-arnd@arndb.de/
Cc: Guido Günther <agx@sigxcpu.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
1 file changed