This is a follow up to commit c4781dc3d1cf ("Kbuild: enable
-fms-extensions") but in a separate change due to being substantially
different from the initial submission.

There are many places within the kernel that use their own CFLAGS
instead of the main KBUILD_CFLAGS, meaning code written with the main
kernel's use of '-fms-extensions' in mind that may be tangentially
included in these areas will result in "error: declaration does not
declare anything" messages from the compiler.

Add '-fms-extensions' to all these areas to ensure consistency, along
with -Wno-microsoft-anon-tag to silence clang's warning about use of the
extension that the kernel cares about using. parisc does not build with
clang so it does not need this warning flag. LoongArch does not need it
either because -W flags from KBUILD_FLAGS are pulled into cflags-vdso.

Reported-by: Christian Brauner <brauner@kernel.org>
Closes: https://lore.kernel.org/20251030-meerjungfrau-getrocknet-7b46eacc215d@brauner/
Reviewed-by: Christian Brauner <brauner@kernel.org>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>

Pull VDSO updates from Thomas Gleixner:

 - Further consolidation of the VDSO infrastructure and the common data
   store

 - Simplification of the related Kconfig logic

 - Improve the VDSO selftest suite

* tag 'timers-vdso-2025-09-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  selftests: vDSO: Drop vdso_test_clock_getres
  selftests: vDSO: vdso_test_abi: Add tests for clock_gettime64()
  selftests: vDSO: vdso_test_abi: Test CPUTIME clocks
  selftests: vDSO: vdso_test_abi: Use explicit indices for name array
  selftests: vDSO: vdso_test_abi: Drop clock availability tests
  selftests: vDSO: vdso_test_abi: Use ksft_finished()
  selftests: vDSO: vdso_test_abi: Correctly skip whole test with missing vDSO
  selftests: vDSO: Fix -Wunitialized in powerpc VDSO_CALL() wrapper
  vdso: Add struct __kernel_old_timeval forward declaration to gettime.h
  vdso: Gate VDSO_GETRANDOM behind HAVE_GENERIC_VDSO
  vdso: Drop Kconfig GENERIC_VDSO_TIME_NS
  vdso: Drop Kconfig GENERIC_VDSO_DATA_STORE
  vdso: Drop kconfig GENERIC_COMPAT_VDSO
  vdso: Drop kconfig GENERIC_VDSO_32
  riscv: vdso: Untangle Kconfig logic
  time: Build generic update_vsyscall() only with generic time vDSO
  vdso/gettimeofday: Remove !CONFIG_TIME_NS stubs
  vdso: Move ENABLE_COMPAT_VDSO from core to arm64
  ARM: VDSO: Remove cntvct_ok global variable
  vdso/datastore: Gate time data behind CONFIG_GENERIC_GETTIMEOFDAY

The compiler flags for the compat vDSO are built manually as they are not
compatible with the ones from kbuild. CONFIG_WERROR is not respected.

Explicitly inherit -Werror from kbuild.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Signed-off-by: Will Deacon <will@kernel.org>

These warnings don't seem to trigger anymore. Probably due to the
introduction of the vdso/ header namespace. Nowadays these suppression
only hide real problems.

Re-enable the warnings.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Signed-off-by: Will Deacon <will@kernel.org>

The ENABLE_COMAPT_VDSO symbol is only used by arm64 and only for the
time-related functionality. There should be no new users, so it doesn't
need to be in the generic vDSO code.

Move the logic into arm64 architecture-specific code and replace the
explicit define by the standard '#ifdef __aarch64__'.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/all/20250826-vdso-cleanups-v1-3-d9b65750e49f@linutronix.de

As the Makefile is included into other Makefiles it can not be used to
define objects to be built from the current source directory.
However the generic datastore will introduce such a local source file.
Rename the included Makefile so it is clear how it is to be used and to
make room for a regular Makefile in lib/vdso/.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20250204-vdso-store-rng-v3-4-13a4669dfc8c@linutronix.de

glibc added support for .gnu.hash in 2006 and .hash has been obsoleted
for more than one decade in many Linux distributions.  Using
--hash-style=sysv might imply unaddressed issues and confuse readers.

Just drop the option and rely on the linker default, which is likely
"both", or "gnu" when the distribution really wants to eliminate sysv
hash overhead.

Similar to commit 6b7e26547fad ("x86/vdso: Emit a GNU hash").

Signed-off-by: Fangrui Song <maskray@google.com>
Link: https://lore.kernel.org/r/20240718173423.1574395-1-maskray@google.com
Signed-off-by: Will Deacon <will@kernel.org>

These are generated files. Prefix them with $(obj)/ instead of $(src)/.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Helge Deller <deller@gmx.de>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>

Commit 2d071968a405 ("arm64: compat: Remove 32-bit sigreturn code
from the vDSO") removed all VDSO_* symbols in the compat vDSO. As a
result, vdso32-offsets.h is now empty and therefore unused. Time to
remove it.

Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
Link: https://lore.kernel.org/r/20240129154748.1727759-1-kevin.brodsky@arm.com
Signed-off-by: Will Deacon <will@kernel.org>

'make vdso_install' renames arch/arm64/kernel/vdso32/vdso.so.dbg to
vdso32.so during installation, which allows 64-bit and 32-bit vdso
files to be installed in the same directory.

However, arm64 is the only architecture that requires this renaming.

To simplify the vdso_install logic, rename the in-tree vdso file so
its base name matches the installed file name.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Link: https://lore.kernel.org/r/20231117125620.1058300-1-masahiroy@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>