vDSO: Respect COMPAT_32BIT_TIME

If CONFIG_COMPAT_32BIT_TIME is disabled then the vDSO should not
provide any 32-bit time related functionality. This is the intended
effect of the kconfig option and also the fallback system calls would
also not be implemented.

I also tried to introduce some helpers to avoid much of the ifdeffery,
but due to the high variance in the architecture-specific glue code
these would need to handle, they ended up being worse than the current
proposal.

As a side-effect this will make the self-tests more reliable,
as there is now always a matching syscall available for each vDSO function.

clock_getres_time64() was only introduced in v6.19, so libc implementations
are likely not using it yet.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
---
Changes in v3:
- Pick up tags.
- Fix incorrect references gettimeofday() in per-arch commit messages.
- Test for CONFIG_COMPAT_32BIT_TIME over __WANT_OLD_TIME_TYPE_SYSCALL in compat_settimeofday()
- Link to v2: https://patch.msgid.link/20260630-vdso-compat_32bit_time-...

Changes in v2:
- Also handle SPARC.
- Drop MIPS cleanup patches.
- Also handle gettimeofday().
- Add more static validations.
- Rebase on v7.2-rc1.
- Link to v1: https://lore.kernel.org/r/20260227-vdso-compat_32bit_time...

To: Andy Lutomirski <luto@kernel.org>
To: Thomas Gleixner <tglx@kernel.org>
To: Ingo Molnar <mingo@redhat.com>
To: Borislav Petkov <bp@alien8.de>
To: Dave Hansen <dave.hansen@linux.intel.com>
To: x86@kernel.org
To: H. Peter Anvin <hpa@zytor.com>
To: Russell King <linux@armlinux.org.uk>
To: Catalin Marinas <catalin.marinas@arm.com>
To: Will Deacon <will@kernel.org>
To: Madhavan Srinivasan <maddy@linux.ibm.com>
To: Michael Ellerman <mpe@ellerman.id.au>
To: Nicholas Piggin <npiggin@gmail.com>
To: Christophe Leroy (CS GROUP) <chleroy@kernel.org>
To: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
To: Vincenzo Frascino <vincenzo.frascino@arm.com>
To: John Stultz <jstultz@google.com>
To: Stephen Boyd <sboyd@kernel.org>
To: "David S. Miller" <davem@davemloft.net>
To: Andreas Larsson <andreas@gaisler.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-mips@vger.kernel.org
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: linux-api@vger.kernel.org
Cc: sparclinux@vger.kernel.org
Cc: Philippe Mathieu-Daudé <philmd@oss.qualcomm.com>

---
Thomas Weißschuh (9):
      time: Respect COMPAT_32BIT_TIME for old time type functions
      vdso/gettimeofday: Validate system call existence for time() and gettimeofday()
      x86/vdso: Respect COMPAT_32BIT_TIME
      arm64: vdso32: Respect COMPAT_32BIT_TIME
      ARM: VDSO: Respect COMPAT_32BIT_TIME
      powerpc/vdso: Respect COMPAT_32BIT_TIME
      MIPS: VDSO: Respect COMPAT_32BIT_TIME
      sparc: vdso: Respect COMPAT_32BIT_TIME
      vdso/gettimeofday: Verify COMPAT_32BIT_TIME interactions

 arch/arm/vdso/vdso.lds.S                    |  2 ++
 arch/arm/vdso/vgettimeofday.c               | 14 ++++++++------
 arch/arm64/kernel/vdso32/vdso.lds.S         |  2 ++
 arch/arm64/kernel/vdso32/vgettimeofday.c    | 14 ++++++++------
 arch/mips/vdso/vdso.lds.S                   |  2 ++
 arch/mips/vdso/vgettimeofday.c              |  3 +++
 arch/powerpc/kernel/vdso/gettimeofday.S     |  8 ++++++++
 arch/powerpc/kernel/vdso/vdso32.lds.S       |  8 +++++---
 arch/powerpc/kernel/vdso/vgettimeofday.c    | 16 ++++++++++------
 arch/sparc/vdso/vclock_gettime.c            |  4 ++++
 arch/sparc/vdso/vdso32/vdso32.lds.S         |  6 ++++--
 arch/x86/entry/vdso/common/vclock_gettime.c | 20 ++++++++++++--------
 arch/x86/entry/vdso/vdso32/vdso32.lds.S     |  2 ++
 kernel/sys_ni.c                             |  4 ++++
 kernel/time/time.c                          | 24 ++++++++++++++++++++----
 lib/vdso/gettimeofday.c                     | 20 ++++++++++++++++++++
 16 files changed, 114 insertions(+), 35 deletions(-)
---
base-commit: e6da2429169af9b33f3629b69905d89bb5ee9e64
change-id: 20260113-vdso-compat_32bit_time-e808763e976a

Best regards,
--  
Thomas Weißschuh (Schneider Electric) <thomas.weissschuh@linutronix.de>