[PATCH v6 00/14] sparc64: vdso: Switch to the generic vDSO library

[Thomas Weißschuh]

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-arnd@kernel.org/

SPARC64 can not map .bss into userspace, so the vDSO datapages are
switched over to be allocated dynamically.

Tested on a Niagara T4 and QEMU.

This has emantic conflicts with
* "vdso: Reject absolute relocations during build" [0]
* "vDSO: Respect COMPAT_32BIT_TIME" [1]

But I expect both other serieses to need more discussions.

[0] https://lore.kernel.org/lkml/20250812-vdso-absolute-reloc-v4-0-61a8b615e5ec@linutronix.de/
[1] https://lore.kernel.org/lkml/20260227-vdso-compat_32bit_time-v1-0-3f0286a7bac3@linutronix.de/

Signed-off-by: Thomas Weißschuh <thomas.weissschuh at linutronix.de>
---
Changes in v6:
- Provide statically allocated during early boot to avoid canges to the rng core
- Use non-compound data pages
- Reword commit messages
- Rebase on v7.0-rc1
- Link to v5: https://lore.kernel.org/r/20251106-vdso-sparc64-generic-2-v5-0-97ff2b6542f7@linutronix.de

Changes in v5:
- Merge the patches for 'struct page' mapping and dynamic allocation
- Zero out newly-allocated data pages
- Pick up review tags
- Link to v4: https://lore.kernel.org/r/20251014-vdso-sparc64-generic-2-v4-0-e0607bf49dea@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-v3-0-3679b1bc8ee8@linutronix.de

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-v2-0-b5ff80672347@linutronix.de

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-v1-0-e376a3bd24d1@linutronix.de

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

Thomas Weißschuh (13):
      vdso/datastore: Reduce scope of some variables in vvar_fault()
      vdso/datastore: Drop inclusion of linux/mmap_lock.h
      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/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 ++-------------------
 include/linux/clocksource.h                |   6 +-
 include/linux/vdso_datastore.h             |   6 +
 init/main.c                                |   2 +
 kernel/time/Kconfig                        |   4 -
 lib/vdso/datastore.c                       |  97 +++++---
 27 files changed, 375 insertions(+), 943 deletions(-)
---
base-commit: f02e02079ac56b44ff89d4c2189cf7185ab794f3
change-id: 20250722-vdso-sparc64-generic-2-25f2e058e92c

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