Re: [PATCH v5 00/34] sparc64: vdso: Switch to the generic vDSO library

["Aithal, Srikanth" <sraithal@amd.com>]

On 11/6/2025 3:31 PM, Thomas WeiÃschuh wrote:
> 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. 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-v4-0-61a8b615e5ec@linutronix.de/
> 
> Signed-off-by: Thomas Weißschuh <thomas.weissschuh@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 (33):
>        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: 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                               |  74 ++--
>   lib/vdso/getrandom.c                               |   3 +
>   lib/vdso/gettimeofday.c                            |  17 +
>   .../testing/selftests/vDSO/vdso_test_correctness.c |   8 +-
>   44 files changed, 449 insertions(+), 994 deletions(-)
> ---
> base-commit: 28b1ac5ccd8d4900a8f53f0e6e84d517a7ccc71f
> change-id: 20250722-vdso-sparc64-generic-2-25f2e058e92c
> 
> Best regards,

The regression [1] v4 series patchset [2] had caused as part of [3]
has been fixed by this series.

Tested-by: Srikanth Aithal <sraithal@amd.com>

[1] 
https://lore.kernel.org/all/977b68ad-6796-4c3d-9c34-d023597f8ab2@amd.com/T/#u
[2] 
https://lore.kernel.org/all/977b68ad-6796-4c3d-9c34-d023597f8ab2@amd.com/T/#m5a310ed22ed9203672b0d0d85ecda0a8fec481c4 
specifically "[PATCH v4 24/35] vdso/datastore: Allocate data pages 
dynamically"
[3] next-20251103, 
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git