kernel/linux.git/lib/vdso/gettimeofday.c, branch v7.1

vdso/gettimeofday: Reload sequence counter after switch to time page in do_aux()

2026-05-14T10:30:53+00:00

After switching to the real data pages, the sequence counter needs to be reloaded from there. The code using vdso_read_begin_timens() assumed this worked by 'continue' jumping to the *beginning* of the do-while retry loop. However the 'continue' jumps to the *end* of said loop, evaluating the exit condition. If the data page has a sequence counter of '1' it will match the one from the time namespace page and prematurely exit the retry loop. This would result in garbage returned to the caller. Reload the sequence counter after switching the pages by using an inner while loop again, which will loop at most once. The loop generates slightly better code than an explicit reload through 'seq = vdso_read_begin()'. Fixes: ed78b7b2c5ae ("vdso/gettimeofday: Add a helper to read the sequence lock of a time namespace aware clock") Reported-by: Ricardo Ribalda Signed-off-by: Thomas Weißschuh Signed-off-by: Thomas Gleixner Tested-by: Ricardo Ribalda Reviewed-by: Christophe Leroy (CS GROUP) Link: https://patch.msgid.link/20260422-vdso-aux-timens-loop-v1-1-e2dd8c7164cc@linutronix.de Closes: https://lore.kernel.org/lkml/CANiDSCsOy0P1if-gJZqOM5pTJ0RDcwVfru1B7KFbTOEMqjPKJw@mail.gmail.com/

vdso/datapage: Remove inclusion of gettimeofday.h

2026-03-11T14:22:32+00:00

vdso/datapage.h is useful without pulling in the architecture-specific gettimeofday() helpers. Move the include to the only users which needs it. Signed-off-by: Thomas Weißschuh Signed-off-by: Thomas Gleixner Signed-off-by: Borislav Petkov (AMD) Link: https://patch.msgid.link/20260227-vdso-header-cleanups-v2-12-35d60acf7410@linutronix.de

vdso/gettimeofday: Add explicit includes

2026-03-11T14:13:00+00:00

Various used symbols are only visible through transitive includes. These transitive includes are about to go away. Explicitly include the necessary headers. Signed-off-by: Thomas Weißschuh Signed-off-by: Thomas Gleixner Signed-off-by: Borislav Petkov (AMD) Link: https://patch.msgid.link/20260227-vdso-header-cleanups-v2-10-35d60acf7410@linutronix.de

vdso/gettimeofday: Move the unlikely() into vdso_read_retry()

2026-03-11T14:12:05+00:00

All callers of vdso_read_retry() test its return value with unlikely(). Move the unlikely into the helper to make the code easier to read. This is equivalent to the retry function of non-vDSO seqlocks. Signed-off-by: Thomas Weißschuh Signed-off-by: Thomas Gleixner Signed-off-by: Borislav Petkov (AMD) Link: https://patch.msgid.link/20260227-vdso-cleanups-v1-4-c848b4bc4850@linutronix.de

vdso/gettimeofday: Add a helper to test if a clock is namespaced

2026-03-11T14:09:59+00:00

Currently this logic is duplicate multiple times. Add a helper for it to make the code more readable. [ bp: Add a missing clocksource.h include, see https://lore.kernel.org/r/20260311113435-f72f81d8-33a6-4a0f-bd80-4997aad068cc@linutronix.de ] Signed-off-by: Thomas Weißschuh Signed-off-by: Thomas Gleixner Signed-off-by: Borislav Petkov (AMD) Link: https://patch.msgid.link/20260227-vdso-cleanups-v1-3-c848b4bc4850@linutronix.de

vdso/gettimeofday: Add a helper to read the sequence lock of a time namespace aware clock

2026-03-11T09:27:35+00:00

Currently there are three different open-coded variants of a time namespace aware variant of vdso_read_begin(). They make the code hard to read and introduce an inconsistency, as only the first copy uses unlikely(). Split the code into a shared helper function. Move that next to the definition of the regular vdso_read_begin(), so that any future changes can be kept in sync easily. Signed-off-by: Thomas Weißschuh Signed-off-by: Thomas Gleixner Link: https://patch.msgid.link/20260227-vdso-cleanups-v1-2-c848b4bc4850@linutronix.de

vdso/gettimeofday: Drop a few usages of __maybe_unused

2026-03-11T09:27:35+00:00

These functions are used from the very same file, so this annotation is unnecessary. Signed-off-by: Thomas Weißschuh Signed-off-by: Thomas Gleixner Link: https://patch.msgid.link/20260227-vdso-cleanups-v1-1-c848b4bc4850@linutronix.de

vdso/gettimeofday: Force inlining of __cvdso_clock_getres_common()

2026-01-26T21:27:07+00:00

With CONFIG_CC_OPTIMIZE_FOR_SIZE=y, GCC may decide not to inline __cvdso_clock_getres_common(). This introduces spurious internal function calls in the vDSO fastpath. Furthermore, with automatic stack variable initialization (CONFIG_INIT_STACK_ALL_ZERO or CONFIG_INIT_STACK_ALL_PATTERN) GCC can emit a call to memset() which is not valid in the vDSO. Mark __cvdso_clock_getres_common() as __always_inline to avoid both issues. Paradoxically the inlining even reduces the size of the code: $ ./scripts/bloat-o-meter arch/powerpc/kernel/vdso/vgettimeofday-32.o.before arch/powerpc/kernel/vdso/vgettimeofday-32.o.after add/remove: 0/1 grow/shrink: 1/1 up/down: 52/-148 (-96) Function old new delta __c_kernel_clock_getres_time64 92 144 +52 __c_kernel_clock_getres 136 132 -4 __cvdso_clock_getres_common 144 - -144 Total: Before=2788, After=2692, chg -3.44% With CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE=y the functions are always inlined and therefore the behaviour stays the same. See also the equivalent change for clock_gettime() in commit b91c8c42ffdd ("lib/vdso: Force inlining of __cvdso_clock_gettime_common()"). Fixes: 21bbfd74044f ("x86/vdso: Provide clock_getres_time64() for x86-32") Fixes: 1149dcdfc9ef ("ARM: VDSO: Provide clock_getres_time64()") Fixes: f10c2e72b5de ("arm64: vdso32: Provide clock_getres_time64()") Fixes: bec06cd6a140 ("MIPS: vdso: Provide getres_time64() for 32-bit ABIs") Fixes: 759a1f97373f ("powerpc/vdso: Provide clock_getres_time64()") Reported-by: Sverdlin, Alexander Suggested-by: Christophe Leroy (CS GROUP) Signed-off-by: Thomas Weißschuh Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/lkml/230c749f-ebd6-4829-93ee-601d88000a45@kernel.org/ Link: https://patch.msgid.link/20260123-vdso-clock_getres-inline-v1-1-4d6203b90cd3@linutronix.de Closes: https://lore.kernel.org/lkml/f45316f65a46da638b3c6aa69effd8980e6677b9.camel@siemens.com/

vdso: Drop Kconfig GENERIC_VDSO_DATA_STORE

2025-09-04T09:23:50+00:00

All users of the generic vDSO library also use the generic vDSO datastore. Remove the now unnecessary Kconfig symbol. Signed-off-by: Thomas Weißschuh Signed-off-by: Thomas Gleixner Acked-by: Catalin Marinas Link: https://lore.kernel.org/all/20250826-vdso-cleanups-v1-9-d9b65750e49f@linutronix.de

vdso/gettimeofday: Remove !CONFIG_TIME_NS stubs

2025-09-04T09:23:49+00:00

All calls of these functions are already gated behind CONFIG_TIME_NS. The compiler will already optimize them away if time namespaces are disabled. Drop the unnecessary stubs. Signed-off-by: Thomas Weißschuh Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/all/20250826-vdso-cleanups-v1-4-d9b65750e49f@linutronix.de