Re: [PATCH 1/7] x86/vdso: Respect COMPAT_32BIT_TIME

Thomas Weißschuh
2026-02-27T09:34:37Z

On Fri, Feb 27, 2026 at 09:58:35AM +0100, Arnd Bergmann wrote:
> On Fri, Feb 27, 2026, at 09:51, Arnd Bergmann wrote:
> > On Fri, Feb 27, 2026, at 07:57, Thomas Weißschuh wrote:
> >> 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.
> >>
> >> Currently the kconfig option does not affect the gettimeofday() syscall,
> >> so also keep that in the vDSO.
> >>
> >> Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
> >
> > Reviewed-by: Arnd Bergmann <arnd@arndb.de>
>
> Actually, I need to revise that. I think gettimeofday() should be
> guarded by CONFIG_COMPAT_32BIT_TIME for both the syscall and the
> vdso. Looking back at the history, I see that we added the #ifdef
> for each syscall we modified to have both time32 and time64 version.
>
> The thing about gettimeofday() and time() is that they don't have
> a 64-bit version and libc implementations are expected to call
> clock_gettime() instead. The result was that there was never a
> patch to turn the off either.

gettimeofday() is currently the only way to get the timezone of the kernel.
But I guess this is a legacy thing anyways. If you say we should drop it,
let's drop it.

Thomas