linux-kernel - Re: [PATCH] powerpc/vdso: Provide clock_getres

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Message-ID: <f0bee121-41cc-4162-8c02-2b279f54c11f@kernel.org>
Date: Thu, 22 Jan 2026 11:27:43 +0100
From: "Christophe Leroy (CS GROUP)" <chleroy@...nel.org>
To: Thomas Weißschuh <thomas.weissschuh@...utronix.de>,
 "Sverdlin, Alexander" <alexander.sverdlin@...mens.com>
Cc: "npiggin@...il.com" <npiggin@...il.com>, "luto@...nel.org"
 <luto@...nel.org>, "maddy@...ux.ibm.com" <maddy@...ux.ibm.com>,
 "tglx@...nel.org" <tglx@...nel.org>, "mpe@...erman.id.au"
 <mpe@...erman.id.au>, "vincenzo.frascino@....com"
 <vincenzo.frascino@....com>,
 "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
 "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] powerpc/vdso: Provide clock_getres_time64()

Hi Thomas,

Le 22/01/2026 à 10:50, Thomas Weißschuh a écrit :
> Hi Alexander,
> 
> On Thu, Jan 22, 2026 at 09:39:09AM +0000, Sverdlin, Alexander wrote:
>> Hi Thomas, Christophe,
>>
>> On Wed, 2026-01-14 at 08:26 +0100, Thomas Weißschuh wrote:
>>> For consistency with __vdso_clock_gettime64() there should also be a
>>> 64-bit variant of clock_getres(). This will allow the extension of
>>> CONFIG_COMPAT_32BIT_TIME to the vDSO and finally the removal of 32-bit
>>> time types from the kernel and UAPI.
>>>
>>> Signed-off-by: Thomas Weißschuh <thomas.weissschuh@...utronix.de>
>>
>> I've bisected this patch to cause the following build failure on my side:
>>
>>    LDS     arch/powerpc/kernel/vdso/vdso32.lds
>>    VDSO32A arch/powerpc/kernel/vdso/sigtramp32-32.o
>>    VDSO32A arch/powerpc/kernel/vdso/gettimeofday-32.o
>>    VDSO32A arch/powerpc/kernel/vdso/datapage-32.o
>>    VDSO32A arch/powerpc/kernel/vdso/cacheflush-32.o
>>    VDSO32A arch/powerpc/kernel/vdso/note-32.o
>>    VDSO32A arch/powerpc/kernel/vdso/getcpu-32.o
>>    VDSO32A arch/powerpc/kernel/vdso/getrandom-32.o
>>    VDSO32A arch/powerpc/kernel/vdso/vgetrandom-chacha-32.o
>>    VDSO32C arch/powerpc/kernel/vdso/vgettimeofday-32.o
>>    VDSO32C arch/powerpc/kernel/vdso/vgetrandom-32.o
>>    VDSO32A arch/powerpc/kernel/vdso/crtsavres-32.o
>>    VDSO32L arch/powerpc/kernel/vdso/vdso32.so.dbg
>> arch/powerpc/kernel/vdso/vdso32.so.dbg: dynamic relocations are not supported
>> make[2]: *** [arch/powerpc/kernel/vdso/Makefile:79: arch/powerpc/kernel/vdso/vdso32.so.dbg] Error 1
>> make[1]: *** [arch/powerpc/Makefile:388: vdso_prepare] Error 2
> 
> Thanks for the report!
> 
>> Does it ring any bells? What could I try/test?
> 
> Not immediately, but I'll look into it.
> 
>> I'm using gcc-15.2.0 and binutils 2.45.1.
> 
> Is this a toolchain from https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fcdn.kernel.org%2Fpub%2Ftools%2Fcrosstool%2F&data=05%7C02%7Cchristophe.leroy%40csgroup.eu%7C03b93d2aa659407b3e5a08de599bb85e%7C8b87af7d86474dc78df45f69a2011bb5%7C0%7C0%7C639046722536758587%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=b9WoZvMR2V3RUpOwrJtm6kmXrpnLti%2BeMJ6zpyB%2Fv4k%3D&reserved=0 ?
> Could you also share your configuration?

I've just been able to reproduce it with ppc64_defconfig + 
CONFIG_CC_OPTIMIZE_FOR_SIZE

   VDSO32L arch/powerpc/kernel/vdso/vdso32.so.dbg
arch/powerpc/kernel/vdso/vdso32.so.dbg: dynamic relocations are not 
supported
make[2]: *** [arch/powerpc/kernel/vdso/Makefile:79: 
arch/powerpc/kernel/vdso/vdso32.so.dbg] Error 1
make[1]: *** [arch/powerpc/Makefile:388: vdso_prepare] Error 2
make: *** [Makefile:248: __sub-make] Error 2

I'll investigate

Christophe

> 
>>> ---
>>> Based on tip/timers/vdso.
>>>
>>> This was missed in the original vdso_getres_time64() series as powerpc
>>> does not use include/vdso/gettime.h.
>>> ---
>>>   arch/powerpc/include/asm/vdso/gettimeofday.h |  2 ++
>>>   arch/powerpc/kernel/vdso/gettimeofday.S      | 12 ++++++++++++
>>>   arch/powerpc/kernel/vdso/vdso32.lds.S        |  1 +
>>>   arch/powerpc/kernel/vdso/vgettimeofday.c     |  6 ++++++
>>>   4 files changed, 21 insertions(+)
> 
> (...)