sparc64: vdso: Switch to the generic vDSO library

The generic vDSO provides a lot common functionality shared between
different architectures. SPARC is the last architecture not using it,
preventing some necessary code cleanup.

Make use of the generic infrastructure.

Follow-up to and replacement for Arnd's SPARC vDSO removal patches:
https://lore.kernel.org/lkml/20250707144726.4008707-1-arn...

SPARC64 can not map .bss into userspace, so the vDSO datapages are
switched over to be allocated dynamically. This requires changes to the
s390 and random subsystem vDSO initialization as preparation.
The random subsystem changes in turn require some cleanup of the vDSO
headers to not end up as ugly #ifdef mess.

Tested on a Niagara T4 and QEMU.

This has a semantic conflict with my series "vdso: Reject absolute
relocations during build" [0]. The last patch of this series expects all
users of the generic vDSO library to use the vdsocheck tool.
This is not the case (yet) for SPARC64. I do have the patches for the
integration, the specifics will depend on which series is applied first.

Based on v6.18-rc1.

[0] https://lore.kernel.org/lkml/20250812-vdso-absolute-reloc...

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
---
Changes in v4:
- Rebase on v6.18-rc1.
- Keep inclusion of asm/clocksource.h from linux/clocksource.h
- Reword description of "s390/time: Set up vDSO datapage later"
- Link to v3: https://lore.kernel.org/r/20250917-vdso-sparc64-generic-2...

Changes in v3:
- Allocate vDSO data pages dynamically (and lots of preparations for that)
- Drop clock_getres()
- Fix 32bit clock_gettime() syscall fallback
- Link to v2: https://lore.kernel.org/r/20250815-vdso-sparc64-generic-2...

Changes in v2:
- Rebase on v6.17-rc1
- Drop RFC state
- Fix typo in commit message
- Drop duplicate 'select GENERIC_TIME_VSYSCALL'
- Merge "sparc64: time: Remove architecture-specific clocksource data" into the
  main conversion patch. It violated the check in __clocksource_register_scale()
- Link to v1: https://lore.kernel.org/r/20250724-vdso-sparc64-generic-2...

---
Arnd Bergmann (1):
      clocksource: remove ARCH_CLOCKSOURCE_DATA

Thomas Weißschuh (34):
      selftests: vDSO: vdso_test_correctness: Handle different tv_usec types
      arm64: vDSO: getrandom: Explicitly include asm/alternative.h
      arm64: vDSO: gettimeofday: Explicitly include vdso/clocksource.h
      arm64: vDSO: compat_gettimeofday: Add explicit includes
      ARM: vdso: gettimeofday: Add explicit includes
      powerpc/vdso/gettimeofday: Explicitly include vdso/time32.h
      powerpc/vdso: Explicitly include asm/cputable.h and asm/feature-fixups.h
      LoongArch: vDSO: Explicitly include asm/vdso/vdso.h
      MIPS: vdso: Add include guard to asm/vdso/vdso.h
      MIPS: vdso: Explicitly include asm/vdso/vdso.h
      random: vDSO: Add explicit includes
      vdso/gettimeofday: Add explicit includes
      vdso/helpers: Explicitly include vdso/processor.h
      vdso/datapage: Remove inclusion of gettimeofday.h
      vdso/datapage: Trim down unnecessary includes
      random: vDSO: trim vDSO includes
      random: vDSO: remove ifdeffery
      random: vDSO: split out datapage update into helper functions
      random: vDSO: only access vDSO datapage after random_init()
      s390/time: Set up vDSO datapage later
      vdso/datastore: Reduce scope of some variables in vvar_fault()
      vdso/datastore: Drop inclusion of linux/mmap_lock.h
      vdso/datastore: Map pages through struct page
      vdso/datastore: Allocate data pages dynamically
      sparc64: vdso: Link with -z noexecstack
      sparc64: vdso: Remove obsolete "fake section table" reservation
      sparc64: vdso: Replace code patching with runtime conditional
      sparc64: vdso: Move hardware counter read into header
      sparc64: vdso: Move syscall fallbacks into header
      sparc64: vdso: Introduce vdso/processor.h
      sparc64: vdso: Switch to the generic vDSO library
      sparc64: vdso2c: Drop sym_vvar_start handling
      sparc64: vdso2c: Remove symbol handling
      sparc64: vdso: Implement clock_gettime64()

 arch/arm/include/asm/vdso/gettimeofday.h           |   2 +
 arch/arm64/include/asm/vdso/compat_gettimeofday.h  |   3 +
 arch/arm64/include/asm/vdso/gettimeofday.h         |   2 +
 arch/arm64/kernel/vdso/vgetrandom.c                |   2 +
 arch/loongarch/kernel/process.c                    |   1 +
 arch/loongarch/kernel/vdso.c                       |   1 +
 arch/mips/include/asm/vdso/vdso.h                  |   5 +
 arch/mips/kernel/vdso.c                            |   1 +
 arch/powerpc/include/asm/vdso/gettimeofday.h       |   1 +
 arch/powerpc/include/asm/vdso/processor.h          |   3 +
 arch/s390/kernel/time.c                            |   4 +-
 arch/sparc/Kconfig                                 |   3 +-
 arch/sparc/include/asm/clocksource.h               |   9 -
 arch/sparc/include/asm/processor.h                 |   3 +
 arch/sparc/include/asm/processor_32.h              |   2 -
 arch/sparc/include/asm/processor_64.h              |  25 --
 arch/sparc/include/asm/vdso.h                      |   2 -
 arch/sparc/include/asm/vdso/clocksource.h          |  10 +
 arch/sparc/include/asm/vdso/gettimeofday.h         | 184 ++++++++++
 arch/sparc/include/asm/vdso/processor.h            |  41 +++
 arch/sparc/include/asm/vdso/vsyscall.h             |  10 +
 arch/sparc/include/asm/vvar.h                      |  75 ----
 arch/sparc/kernel/Makefile                         |   1 -
 arch/sparc/kernel/time_64.c                        |   6 +-
 arch/sparc/kernel/vdso.c                           |  69 ----
 arch/sparc/vdso/Makefile                           |   8 +-
 arch/sparc/vdso/vclock_gettime.c                   | 380 ++-------------------
 arch/sparc/vdso/vdso-layout.lds.S                  |  26 +-
 arch/sparc/vdso/vdso.lds.S                         |   2 -
 arch/sparc/vdso/vdso2c.c                           |  24 --
 arch/sparc/vdso/vdso2c.h                           |  45 +--
 arch/sparc/vdso/vdso32/vdso32.lds.S                |   4 +-
 arch/sparc/vdso/vma.c                              | 274 +--------------
 drivers/char/random.c                              |  71 ++--
 include/linux/clocksource.h                        |   6 +-
 include/linux/vdso_datastore.h                     |   6 +
 include/vdso/datapage.h                            |  23 +-
 include/vdso/helpers.h                             |   1 +
 init/main.c                                        |   2 +
 kernel/time/Kconfig                                |   4 -
 lib/vdso/datastore.c                               |  73 ++--
 lib/vdso/getrandom.c                               |   3 +
 lib/vdso/gettimeofday.c                            |  17 +
 .../testing/selftests/vDSO/vdso_test_correctness.c |   8 +-
 44 files changed, 448 insertions(+), 994 deletions(-)
---
base-commit: 28b1ac5ccd8d4900a8f53f0e6e84d517a7ccc71f
change-id: 20250722-vdso-sparc64-generic-2-25f2e058e92c

Best regards,
-- 
Thomas Weißschuh <thomas.weissschuh@linutronix.de>