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(+)
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@linutronix.de>
---
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(+)
diff --git a/arch/powerpc/include/asm/vdso/gettimeofday.h b/arch/powerpc/include/asm/vdso/gettimeofday.h
index ab3df12c8d94..8ea397e26ad0 100644
--- a/arch/powerpc/include/asm/vdso/gettimeofday.h
+++ b/arch/powerpc/include/asm/vdso/gettimeofday.h
@@ -135,6 +135,8 @@ int __c_kernel_clock_gettime64(clockid_t clock, struct __kernel_timespec *ts,
const struct vdso_time_data *vd);
int __c_kernel_clock_getres(clockid_t clock_id, struct old_timespec32 *res,
const struct vdso_time_data *vd);
+int __c_kernel_clock_getres_time64(clockid_t clock_id, struct __kernel_timespec *res,
+ const struct vdso_time_data *vd);
#endif
int __c_kernel_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz,
const struct vdso_time_data *vd);
diff --git a/arch/powerpc/kernel/vdso/gettimeofday.S b/arch/powerpc/kernel/vdso/gettimeofday.S
index 79c967212444..1c8e51691bf8 100644
--- a/arch/powerpc/kernel/vdso/gettimeofday.S
+++ b/arch/powerpc/kernel/vdso/gettimeofday.S
@@ -103,6 +103,18 @@ V_FUNCTION_BEGIN(__kernel_clock_getres)
cvdso_call __c_kernel_clock_getres
V_FUNCTION_END(__kernel_clock_getres)
+/*
+ * Exact prototype of clock_getres_time64()
+ *
+ * int __kernel_clock_getres(clockid_t clock_id, struct __timespec64 *res);
+ *
+ */
+#ifndef __powerpc64__
+V_FUNCTION_BEGIN(__kernel_clock_getres_time64)
+ cvdso_call __c_kernel_clock_getres_time64
+V_FUNCTION_END(__kernel_clock_getres_time64)
+#endif
+
/*
* Exact prototype of time()
diff --git a/arch/powerpc/kernel/vdso/vdso32.lds.S b/arch/powerpc/kernel/vdso/vdso32.lds.S
index 72a1012b8a20..3f384a2526ae 100644
--- a/arch/powerpc/kernel/vdso/vdso32.lds.S
+++ b/arch/powerpc/kernel/vdso/vdso32.lds.S
@@ -124,6 +124,7 @@ VERSION
__kernel_clock_gettime;
__kernel_clock_gettime64;
__kernel_clock_getres;
+ __kernel_clock_getres_time64;
__kernel_time;
__kernel_get_tbfreq;
__kernel_sync_dicache;
diff --git a/arch/powerpc/kernel/vdso/vgettimeofday.c b/arch/powerpc/kernel/vdso/vgettimeofday.c
index 6f5167d81af5..3c194e1ab562 100644
--- a/arch/powerpc/kernel/vdso/vgettimeofday.c
+++ b/arch/powerpc/kernel/vdso/vgettimeofday.c
@@ -35,6 +35,12 @@ int __c_kernel_clock_getres(clockid_t clock_id, struct old_timespec32 *res,
{
return __cvdso_clock_getres_time32_data(vd, clock_id, res);
}
+
+int __c_kernel_clock_getres_time64(clockid_t clock_id, struct __kernel_timespec *res,
+ const struct vdso_time_data *vd)
+{
+ return __cvdso_clock_getres_data(vd, clock_id, res);
+}
#endif
int __c_kernel_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz,
---
base-commit: 0e55e7636697077abceb2301d7d2718d75c34389
change-id: 20260113-vdso-powerpc-align-e8e93664da2b
Best regards,
--
Thomas Weißschuh <thomas.weissschuh@linutronix.de>
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@linutronix.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
Does it ring any bells? What could I try/test?
I'm using gcc-15.2.0 and binutils 2.45.1.
> ---
> 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(+)
>
> diff --git a/arch/powerpc/include/asm/vdso/gettimeofday.h b/arch/powerpc/include/asm/vdso/gettimeofday.h
> index ab3df12c8d94..8ea397e26ad0 100644
> --- a/arch/powerpc/include/asm/vdso/gettimeofday.h
> +++ b/arch/powerpc/include/asm/vdso/gettimeofday.h
> @@ -135,6 +135,8 @@ int __c_kernel_clock_gettime64(clockid_t clock, struct __kernel_timespec *ts,
> const struct vdso_time_data *vd);
> int __c_kernel_clock_getres(clockid_t clock_id, struct old_timespec32 *res,
> const struct vdso_time_data *vd);
> +int __c_kernel_clock_getres_time64(clockid_t clock_id, struct __kernel_timespec *res,
> + const struct vdso_time_data *vd);
> #endif
> int __c_kernel_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz,
> const struct vdso_time_data *vd);
> diff --git a/arch/powerpc/kernel/vdso/gettimeofday.S b/arch/powerpc/kernel/vdso/gettimeofday.S
> index 79c967212444..1c8e51691bf8 100644
> --- a/arch/powerpc/kernel/vdso/gettimeofday.S
> +++ b/arch/powerpc/kernel/vdso/gettimeofday.S
> @@ -103,6 +103,18 @@ V_FUNCTION_BEGIN(__kernel_clock_getres)
> cvdso_call __c_kernel_clock_getres
> V_FUNCTION_END(__kernel_clock_getres)
>
> +/*
> + * Exact prototype of clock_getres_time64()
> + *
> + * int __kernel_clock_getres(clockid_t clock_id, struct __timespec64 *res);
> + *
> + */
> +#ifndef __powerpc64__
> +V_FUNCTION_BEGIN(__kernel_clock_getres_time64)
> + cvdso_call __c_kernel_clock_getres_time64
> +V_FUNCTION_END(__kernel_clock_getres_time64)
> +#endif
> +
>
> /*
> * Exact prototype of time()
> diff --git a/arch/powerpc/kernel/vdso/vdso32.lds.S b/arch/powerpc/kernel/vdso/vdso32.lds.S
> index 72a1012b8a20..3f384a2526ae 100644
> --- a/arch/powerpc/kernel/vdso/vdso32.lds.S
> +++ b/arch/powerpc/kernel/vdso/vdso32.lds.S
> @@ -124,6 +124,7 @@ VERSION
> __kernel_clock_gettime;
> __kernel_clock_gettime64;
> __kernel_clock_getres;
> + __kernel_clock_getres_time64;
> __kernel_time;
> __kernel_get_tbfreq;
> __kernel_sync_dicache;
> diff --git a/arch/powerpc/kernel/vdso/vgettimeofday.c b/arch/powerpc/kernel/vdso/vgettimeofday.c
> index 6f5167d81af5..3c194e1ab562 100644
> --- a/arch/powerpc/kernel/vdso/vgettimeofday.c
> +++ b/arch/powerpc/kernel/vdso/vgettimeofday.c
> @@ -35,6 +35,12 @@ int __c_kernel_clock_getres(clockid_t clock_id, struct old_timespec32 *res,
> {
> return __cvdso_clock_getres_time32_data(vd, clock_id, res);
> }
> +
> +int __c_kernel_clock_getres_time64(clockid_t clock_id, struct __kernel_timespec *res,
> + const struct vdso_time_data *vd)
> +{
> + return __cvdso_clock_getres_data(vd, clock_id, res);
> +}
> #endif
>
> int __c_kernel_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz,
>
> ---
> base-commit: 0e55e7636697077abceb2301d7d2718d75c34389
> change-id: 20260113-vdso-powerpc-align-e8e93664da2b
>
> Best regards,
--
Alexander Sverdlin
Siemens AG
www.siemens.com
Hi Alexandre,
Le 22/01/2026 à 10:39, Sverdlin, Alexander a écrit :
> 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@linutronix.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
>
> Does it ring any bells? What could I try/test?
>
> I'm using gcc-15.2.0 and binutils 2.45.1.
Can you share your defconfig ?
I don't have such a problem with mpc885_ads_defconfig using same
gcc/binutils as you.
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(+)
>>
>> diff --git a/arch/powerpc/include/asm/vdso/gettimeofday.h b/arch/powerpc/include/asm/vdso/gettimeofday.h
>> index ab3df12c8d94..8ea397e26ad0 100644
>> --- a/arch/powerpc/include/asm/vdso/gettimeofday.h
>> +++ b/arch/powerpc/include/asm/vdso/gettimeofday.h
>> @@ -135,6 +135,8 @@ int __c_kernel_clock_gettime64(clockid_t clock, struct __kernel_timespec *ts,
>> const struct vdso_time_data *vd);
>> int __c_kernel_clock_getres(clockid_t clock_id, struct old_timespec32 *res,
>> const struct vdso_time_data *vd);
>> +int __c_kernel_clock_getres_time64(clockid_t clock_id, struct __kernel_timespec *res,
>> + const struct vdso_time_data *vd);
>> #endif
>> int __c_kernel_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz,
>> const struct vdso_time_data *vd);
>> diff --git a/arch/powerpc/kernel/vdso/gettimeofday.S b/arch/powerpc/kernel/vdso/gettimeofday.S
>> index 79c967212444..1c8e51691bf8 100644
>> --- a/arch/powerpc/kernel/vdso/gettimeofday.S
>> +++ b/arch/powerpc/kernel/vdso/gettimeofday.S
>> @@ -103,6 +103,18 @@ V_FUNCTION_BEGIN(__kernel_clock_getres)
>> cvdso_call __c_kernel_clock_getres
>> V_FUNCTION_END(__kernel_clock_getres)
>>
>> +/*
>> + * Exact prototype of clock_getres_time64()
>> + *
>> + * int __kernel_clock_getres(clockid_t clock_id, struct __timespec64 *res);
>> + *
>> + */
>> +#ifndef __powerpc64__
>> +V_FUNCTION_BEGIN(__kernel_clock_getres_time64)
>> + cvdso_call __c_kernel_clock_getres_time64
>> +V_FUNCTION_END(__kernel_clock_getres_time64)
>> +#endif
>> +
>>
>> /*
>> * Exact prototype of time()
>> diff --git a/arch/powerpc/kernel/vdso/vdso32.lds.S b/arch/powerpc/kernel/vdso/vdso32.lds.S
>> index 72a1012b8a20..3f384a2526ae 100644
>> --- a/arch/powerpc/kernel/vdso/vdso32.lds.S
>> +++ b/arch/powerpc/kernel/vdso/vdso32.lds.S
>> @@ -124,6 +124,7 @@ VERSION
>> __kernel_clock_gettime;
>> __kernel_clock_gettime64;
>> __kernel_clock_getres;
>> + __kernel_clock_getres_time64;
>> __kernel_time;
>> __kernel_get_tbfreq;
>> __kernel_sync_dicache;
>> diff --git a/arch/powerpc/kernel/vdso/vgettimeofday.c b/arch/powerpc/kernel/vdso/vgettimeofday.c
>> index 6f5167d81af5..3c194e1ab562 100644
>> --- a/arch/powerpc/kernel/vdso/vgettimeofday.c
>> +++ b/arch/powerpc/kernel/vdso/vgettimeofday.c
>> @@ -35,6 +35,12 @@ int __c_kernel_clock_getres(clockid_t clock_id, struct old_timespec32 *res,
>> {
>> return __cvdso_clock_getres_time32_data(vd, clock_id, res);
>> }
>> +
>> +int __c_kernel_clock_getres_time64(clockid_t clock_id, struct __kernel_timespec *res,
>> + const struct vdso_time_data *vd)
>> +{
>> + return __cvdso_clock_getres_data(vd, clock_id, res);
>> +}
>> #endif
>>
>> int __c_kernel_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz,
>>
>> ---
>> base-commit: 0e55e7636697077abceb2301d7d2718d75c34389
>> change-id: 20260113-vdso-powerpc-align-e8e93664da2b
>>
>> Best regards,
>
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@linutronix.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://cdn.kernel.org/pub/tools/crosstool/ ? Could you also share your configuration? > > --- > > 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(+) (...)
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@linutronix.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(+) > > (...)
Hi Again,
Le 22/01/2026 à 11:27, Christophe Leroy (CS GROUP) a écrit :
> Hi Thomas,
>
> Le 22/01/2026 à 10:50, Thomas Weißschuh a écrit :
>> Hi Alexander,
>> 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
>
Comes from here, a call to memset():
000007c0 <__c_kernel_clock_getres>:
7c0: 94 21 ff d0 stwu r1,-48(r1)
7c4: 7c 08 02 a6 mflr r0
7c8: bf a1 00 24 stmw r29,36(r1)
7cc: 7c 7e 1b 78 mr r30,r3
7d0: 7c bd 2b 78 mr r29,r5
7d4: 7c 9f 23 78 mr r31,r4
7d8: 38 a0 00 10 li r5,16
7dc: 90 01 00 34 stw r0,52(r1)
7e0: 38 80 00 00 li r4,0
7e4: 38 61 00 08 addi r3,r1,8
7e8: 48 00 00 01 bl 7e8 <__c_kernel_clock_getres+0x28>
7e8: R_PPC_REL24 memset
7ec: 7f c4 f3 78 mr r4,r30
7f0: 7f a3 eb 78 mr r3,r29
7f4: 38 a1 00 08 addi r5,r1,8
7f8: 4b ff f8 09 bl 0 <__cvdso_clock_getres_common>
7fc: 2c 03 00 00 cmpwi r3,0
800: 40 82 00 24 bne 824 <__c_kernel_clock_getres+0x64>
804: 38 00 00 f7 li r0,247
808: 7f c3 f3 78 mr r3,r30
80c: 7f e4 fb 78 mr r4,r31
810: 44 00 00 02 sc
814: 40 e3 00 08 bns+ 81c <__c_kernel_clock_getres+0x5c>
818: 7c 63 00 d0 neg r3,r3
81c: 39 61 00 30 addi r11,r1,48
820: 48 00 00 00 b 820 <__c_kernel_clock_getres+0x60>
820: R_PPC_REL24 _restgpr_29_x
824: 2c 1f 00 00 cmpwi r31,0
828: 41 82 00 14 beq 83c <__c_kernel_clock_getres+0x7c>
82c: 81 21 00 0c lwz r9,12(r1)
830: 91 3f 00 00 stw r9,0(r31)
834: 81 21 00 14 lwz r9,20(r1)
838: 91 3f 00 04 stw r9,4(r31)
83c: 38 60 00 00 li r3,0
840: 4b ff ff dc b 81c <__c_kernel_clock_getres+0x5c>
On Thu, Jan 22, 2026 at 11:27:43AM +0100, Christophe Leroy (CS GROUP) wrote:
> 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@linutronix.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
Thanks for the hint, no I can reproduce it, too.
>
> 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
It seems the compiler decides to call memset(), which is not valid from the
vDSO. We are are using -ffreestanding. Disabling CONFIG_INIT_STACK_ALL_ZERO
fixes the issue. So I guess we should a) figure out why -ffreestanding does
not seem to work here and b) exclude the vDSO from the stack initialization
logic.
000007ac <__c_kernel_clock_getres>:
; __c_kernel_clock_getres():
; arch/powerpc/kernel/vdso/vgettimeofday.c:35
; {
7ac: d0 ff 21 94 stwu 1, -48(1)
7b0: a6 02 08 7c mflr 0
7b4: 30 00 61 39 addi 11, 1, 48
7b8: 34 00 01 90 stw 0, 52(1)
7bc: 01 00 00 48 bl 0x7bc <__c_kernel_clock_getres+0x10>
000007bc: R_PPC_REL24 _savegpr_29
7c0: 78 1b 7e 7c mr 30, 3
7c4: 78 2b bd 7c mr 29, 5
7c8: 78 23 9f 7c mr 31, 4
; lib/vdso/gettimeofday.c:491
; struct __kernel_timespec ts;
7cc: 10 00 a0 38 li 5, 16
7d0: 00 00 80 38 li 4, 0
7d4: 08 00 61 38 addi 3, 1, 8
7d8: 01 00 00 48 bl 0x7d8 <__c_kernel_clock_getres+0x2c>
000007d8: R_PPC_REL24 memset
; lib/vdso/gettimeofday.c:494
; ok = __cvdso_clock_getres_common(vd, clock, &ts);
7dc: 78 f3 c4 7f mr 4, 30
7e0: 78 eb a3 7f mr 3, 29
7e4: 08 00 a1 38 addi 5, 1, 8
7e8: 19 f8 ff 4b bl 0x0 <__cvdso_clock_getres_common>
; lib/vdso/gettimeofday.c:496
(...)
Thomas
Le 22/01/2026 à 11:49, Thomas Weißschuh a écrit :
> On Thu, Jan 22, 2026 at 11:27:43AM +0100, Christophe Leroy (CS GROUP) wrote:
>> 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@linutronix.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%7C937051154ddf479721f708de59a3e01c%7C8b87af7d86474dc78df45f69a2011bb5%7C0%7C0%7C639046757528646789%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=qkl4zNfg2j%2F24vZV7nQ7LLDtxG0WbgaJc30kjHQZqpk%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
>
> Thanks for the hint, no I can reproduce it, too.
>>
>> 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
>
> It seems the compiler decides to call memset(), which is not valid from the
> vDSO. We are are using -ffreestanding. Disabling CONFIG_INIT_STACK_ALL_ZERO
> fixes the issue. So I guess we should a) figure out why -ffreestanding does
> not seem to work here and b) exclude the vDSO from the stack initialization
> logic.
>
Ah, ok.
Reminds me commit b91c8c42ffdd ("lib/vdso: Force inlining of
__cvdso_clock_gettime_common()")
Problem fixed with:
diff --git a/lib/vdso/gettimeofday.c b/lib/vdso/gettimeofday.c
index 95df0153f05ab..4399e143d43a5 100644
--- a/lib/vdso/gettimeofday.c
+++ b/lib/vdso/gettimeofday.c
@@ -421,7 +421,7 @@ static __maybe_unused __kernel_old_time_t
__cvdso_time(__kernel_old_time_t *time
#endif /* VDSO_HAS_TIME */
#ifdef VDSO_HAS_CLOCK_GETRES
-static __maybe_unused
+static __always_inline
bool __cvdso_clock_getres_common(const struct vdso_time_data *vd,
clockid_t clock,
struct __kernel_timespec *res)
{
Christophe
On Thu, Jan 22, 2026 at 11:58:04AM +0100, Christophe Leroy (CS GROUP) wrote:
>
>
> Le 22/01/2026 à 11:49, Thomas Weißschuh a écrit :
> > On Thu, Jan 22, 2026 at 11:27:43AM +0100, Christophe Leroy (CS GROUP) wrote:
> > > 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@linutronix.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%7C937051154ddf479721f708de59a3e01c%7C8b87af7d86474dc78df45f69a2011bb5%7C0%7C0%7C639046757528646789%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=qkl4zNfg2j%2F24vZV7nQ7LLDtxG0WbgaJc30kjHQZqpk%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
> >
> > Thanks for the hint, no I can reproduce it, too.
> > >
> > > 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
> >
> > It seems the compiler decides to call memset(), which is not valid from the
> > vDSO. We are are using -ffreestanding. Disabling CONFIG_INIT_STACK_ALL_ZERO
> > fixes the issue. So I guess we should a) figure out why -ffreestanding does
> > not seem to work here and b) exclude the vDSO from the stack initialization
> > logic.
> >
>
> Ah, ok.
>
> Reminds me commit b91c8c42ffdd ("lib/vdso: Force inlining of
> __cvdso_clock_gettime_common()")
Good pointer.
> Problem fixed with:
>
> diff --git a/lib/vdso/gettimeofday.c b/lib/vdso/gettimeofday.c
> index 95df0153f05ab..4399e143d43a5 100644
> --- a/lib/vdso/gettimeofday.c
> +++ b/lib/vdso/gettimeofday.c
> @@ -421,7 +421,7 @@ static __maybe_unused __kernel_old_time_t
> __cvdso_time(__kernel_old_time_t *time
> #endif /* VDSO_HAS_TIME */
>
> #ifdef VDSO_HAS_CLOCK_GETRES
> -static __maybe_unused
> +static __always_inline
> bool __cvdso_clock_getres_common(const struct vdso_time_data *vd, clockid_t
> clock,
> struct __kernel_timespec *res)
> {
Do you want to run the measurements for this one, too and submit a fix?
This should get us past the immediate breakage.
I'll still try to get the stack initialization out of the vDSO.
It might bite us at any time in the future. As these options are meant
to prevent information leaks and the vDSO has no sensitive information in
the first place, we might as well filter them out.
Thomas
Le 22/01/2026 à 12:07, Thomas Weißschuh a écrit :
> On Thu, Jan 22, 2026 at 11:58:04AM +0100, Christophe Leroy (CS GROUP) wrote:
>>
>>
>> Le 22/01/2026 à 11:49, Thomas Weißschuh a écrit :
>>> On Thu, Jan 22, 2026 at 11:27:43AM +0100, Christophe Leroy (CS GROUP) wrote:
>>>> 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@linutronix.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%7C7f1accdfc7ef4d8ea82c08de59a664b8%7C8b87af7d86474dc78df45f69a2011bb5%7C0%7C0%7C639046768343248286%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=7WB%2FCB2ZDhP9bD0GYwEftyRwfDCoRwuQ5uMA98JhfmE%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
>>>
>>> Thanks for the hint, no I can reproduce it, too.
>>>>
>>>> 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
>>>
>>> It seems the compiler decides to call memset(), which is not valid from the
>>> vDSO. We are are using -ffreestanding. Disabling CONFIG_INIT_STACK_ALL_ZERO
>>> fixes the issue. So I guess we should a) figure out why -ffreestanding does
>>> not seem to work here and b) exclude the vDSO from the stack initialization
>>> logic.
>>>
>>
>> Ah, ok.
>>
>> Reminds me commit b91c8c42ffdd ("lib/vdso: Force inlining of
>> __cvdso_clock_gettime_common()")
>
> Good pointer.
>
>> Problem fixed with:
>>
>> diff --git a/lib/vdso/gettimeofday.c b/lib/vdso/gettimeofday.c
>> index 95df0153f05ab..4399e143d43a5 100644
>> --- a/lib/vdso/gettimeofday.c
>> +++ b/lib/vdso/gettimeofday.c
>> @@ -421,7 +421,7 @@ static __maybe_unused __kernel_old_time_t
>> __cvdso_time(__kernel_old_time_t *time
>> #endif /* VDSO_HAS_TIME */
>>
>> #ifdef VDSO_HAS_CLOCK_GETRES
>> -static __maybe_unused
>> +static __always_inline
>> bool __cvdso_clock_getres_common(const struct vdso_time_data *vd, clockid_t
>> clock,
>> struct __kernel_timespec *res)
>> {
>
> Do you want to run the measurements for this one, too and submit a fix?
> This should get us past the immediate breakage.
I'm travelling at the moment and won't be able to come with measurement
before next month. But the performance degradation is obvious.
With the fix, the function is stackless:
00000728 <__c_kernel_clock_getres>:
728: 28 03 00 17 cmplwi r3,23
72c: 41 81 00 50 bgt 77c <__c_kernel_clock_getres+0x54>
730: 81 45 00 04 lwz r10,4(r5)
734: 6d 49 80 00 xoris r9,r10,32768
738: 2c 09 ff ff cmpwi r9,-1
73c: 40 82 00 08 bne 744 <__c_kernel_clock_getres+0x1c>
740: 3c a5 00 01 addis r5,r5,1
744: 39 20 00 01 li r9,1
748: 7d 29 18 30 slw r9,r9,r3
74c: 71 2a 08 93 andi. r10,r9,2195
750: 41 82 00 18 beq 768 <__c_kernel_clock_getres+0x40>
754: 81 25 08 c8 lwz r9,2248(r5)
758: 2c 04 00 00 cmpwi r4,0
75c: 40 82 00 40 bne 79c <__c_kernel_clock_getres+0x74>
760: 38 60 00 00 li r3,0
764: 4e 80 00 20 blr
768: 71 2a 00 60 andi. r10,r9,96
76c: 40 82 00 24 bne 790 <__c_kernel_clock_getres+0x68>
770: 75 29 00 ff andis. r9,r9,255
774: 39 20 00 01 li r9,1
778: 40 82 ff e0 bne 758 <__c_kernel_clock_getres+0x30>
77c: 38 00 00 f7 li r0,247
780: 44 00 00 02 sc
784: 40 e3 00 08 bns+ 78c <__c_kernel_clock_getres+0x64>
788: 7c 63 00 d0 neg r3,r3
78c: 4e 80 00 20 blr
790: 3d 20 00 0f lis r9,15
794: 61 29 42 40 ori r9,r9,16960
798: 4b ff ff c0 b 758 <__c_kernel_clock_getres+0x30>
79c: 39 40 00 00 li r10,0
7a0: 91 24 00 04 stw r9,4(r4)
7a4: 91 44 00 00 stw r10,0(r4)
7a8: 4b ff ff b8 b 760 <__c_kernel_clock_getres+0x38>
Without the fix, see below, __c_kernel_clock_getres() has to setup a
stack in order to call __cvdso_clock_getres_common(), and in addition we
see that __cvdso_clock_getres_common() is more or less the same size as
__c_kernel_clock_getres() above, so time increase unquestionable.
00000000 <__cvdso_clock_getres_common>:
0: 28 04 00 17 cmplwi r4,23
4: 41 81 00 8c bgt 90 <__cvdso_clock_getres_common+0x90>
8: 81 43 00 04 lwz r10,4(r3)
c: 6d 49 80 00 xoris r9,r10,32768
10: 2c 09 ff ff cmpwi r9,-1
14: 40 82 00 08 bne 1c <__cvdso_clock_getres_common+0x1c>
18: 3c 63 00 01 addis r3,r3,1
1c: 39 20 00 01 li r9,1
20: 7d 24 20 30 slw r4,r9,r4
24: 70 89 08 93 andi. r9,r4,2195
28: 41 82 00 34 beq 5c <__cvdso_clock_getres_common+0x5c>
2c: 81 23 08 c8 lwz r9,2248(r3)
30: 39 40 00 00 li r10,0
34: 2c 05 00 00 cmpwi r5,0
38: 41 82 00 1c beq 54 <__cvdso_clock_getres_common+0x54>
3c: 38 c0 00 00 li r6,0
40: 38 e0 00 00 li r7,0
44: 91 45 00 08 stw r10,8(r5)
48: 91 25 00 0c stw r9,12(r5)
4c: 90 c5 00 00 stw r6,0(r5)
50: 90 e5 00 04 stw r7,4(r5)
54: 38 60 00 01 li r3,1
58: 48 00 00 20 b 78 <__cvdso_clock_getres_common+0x78>
5c: 70 89 00 60 andi. r9,r4,96
60: 40 82 00 20 bne 80 <__cvdso_clock_getres_common+0x80>
64: 74 84 00 ff andis. r4,r4,255
68: 38 60 00 00 li r3,0
6c: 39 40 00 00 li r10,0
70: 39 20 00 01 li r9,1
74: 40 82 ff c0 bne 34 <__cvdso_clock_getres_common+0x34>
78: 54 63 07 fe clrlwi r3,r3,31
7c: 4e 80 00 20 blr
80: 3d 20 00 0f lis r9,15
84: 39 40 00 00 li r10,0
88: 61 29 42 40 ori r9,r9,16960
8c: 4b ff ff a8 b 34 <__cvdso_clock_getres_common+0x34>
90: 38 60 00 00 li r3,0
94: 4b ff ff e4 b 78 <__cvdso_clock_getres_common+0x78>
000007c0 <__c_kernel_clock_getres>:
7c0: 94 21 ff d0 stwu r1,-48(r1)
7c4: 7c 08 02 a6 mflr r0
7c8: bf a1 00 24 stmw r29,36(r1)
7cc: 7c 7e 1b 78 mr r30,r3
7d0: 7c bd 2b 78 mr r29,r5
7d4: 7c 9f 23 78 mr r31,r4
7d8: 38 a0 00 10 li r5,16
7dc: 90 01 00 34 stw r0,52(r1)
7e0: 38 80 00 00 li r4,0
7e4: 38 61 00 08 addi r3,r1,8
7e8: 48 00 00 01 bl 7e8 <__c_kernel_clock_getres+0x28>
7e8: R_PPC_REL24 memset
7ec: 7f c4 f3 78 mr r4,r30
7f0: 7f a3 eb 78 mr r3,r29
7f4: 38 a1 00 08 addi r5,r1,8
7f8: 4b ff f8 09 bl 0 <__cvdso_clock_getres_common>
7fc: 2c 03 00 00 cmpwi r3,0
800: 40 82 00 24 bne 824 <__c_kernel_clock_getres+0x64>
804: 38 00 00 f7 li r0,247
808: 7f c3 f3 78 mr r3,r30
80c: 7f e4 fb 78 mr r4,r31
810: 44 00 00 02 sc
814: 40 e3 00 08 bns+ 81c <__c_kernel_clock_getres+0x5c>
818: 7c 63 00 d0 neg r3,r3
81c: 39 61 00 30 addi r11,r1,48
820: 48 00 00 00 b 820 <__c_kernel_clock_getres+0x60>
820: R_PPC_REL24 _restgpr_29_x
824: 2c 1f 00 00 cmpwi r31,0
828: 41 82 00 14 beq 83c <__c_kernel_clock_getres+0x7c>
82c: 81 21 00 0c lwz r9,12(r1)
830: 91 3f 00 00 stw r9,0(r31)
834: 81 21 00 14 lwz r9,20(r1)
838: 91 3f 00 04 stw r9,4(r31)
83c: 38 60 00 00 li r3,0
840: 4b ff ff dc b 81c <__c_kernel_clock_getres+0x5c>
>
> I'll still try to get the stack initialization out of the vDSO.
> It might bite us at any time in the future. As these options are meant
> to prevent information leaks and the vDSO has no sensitive information in
> the first place, we might as well filter them out.
Well, from the first day we converted powerpc to C time vdso, we've done
our best in order to keep vdso stackless. So I'm not sure it is worth
dealing with the above. Indeed if keeping it as is helps us detect
everytime a change jeoperdises the stackless approach, that's not bad.
Christophe
On Thu, Jan 22, 2026 at 12:31:32PM +0100, Christophe Leroy (CS GROUP) wrote:
> Le 22/01/2026 à 12:07, Thomas Weißschuh a écrit :
> > On Thu, Jan 22, 2026 at 11:58:04AM +0100, Christophe Leroy (CS GROUP) wrote:
> > >
> > >
> > > Le 22/01/2026 à 11:49, Thomas Weißschuh a écrit :
> > > > On Thu, Jan 22, 2026 at 11:27:43AM +0100, Christophe Leroy (CS GROUP) wrote:
> > > > > 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@linutronix.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%7C7f1accdfc7ef4d8ea82c08de59a664b8%7C8b87af7d86474dc78df45f69a2011bb5%7C0%7C0%7C639046768343248286%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=7WB%2FCB2ZDhP9bD0GYwEftyRwfDCoRwuQ5uMA98JhfmE%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
> > > >
> > > > Thanks for the hint, no I can reproduce it, too.
> > > > >
> > > > > 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
> > > >
> > > > It seems the compiler decides to call memset(), which is not valid from the
> > > > vDSO. We are are using -ffreestanding. Disabling CONFIG_INIT_STACK_ALL_ZERO
> > > > fixes the issue. So I guess we should a) figure out why -ffreestanding does
> > > > not seem to work here and b) exclude the vDSO from the stack initialization
> > > > logic.
> > > >
> > >
> > > Ah, ok.
> > >
> > > Reminds me commit b91c8c42ffdd ("lib/vdso: Force inlining of
> > > __cvdso_clock_gettime_common()")
> >
> > Good pointer.
> >
> > > Problem fixed with:
> > >
> > > diff --git a/lib/vdso/gettimeofday.c b/lib/vdso/gettimeofday.c
> > > index 95df0153f05ab..4399e143d43a5 100644
> > > --- a/lib/vdso/gettimeofday.c
> > > +++ b/lib/vdso/gettimeofday.c
> > > @@ -421,7 +421,7 @@ static __maybe_unused __kernel_old_time_t
> > > __cvdso_time(__kernel_old_time_t *time
> > > #endif /* VDSO_HAS_TIME */
> > >
> > > #ifdef VDSO_HAS_CLOCK_GETRES
> > > -static __maybe_unused
> > > +static __always_inline
> > > bool __cvdso_clock_getres_common(const struct vdso_time_data *vd, clockid_t
> > > clock,
> > > struct __kernel_timespec *res)
> > > {
> >
> > Do you want to run the measurements for this one, too and submit a fix?
> > This should get us past the immediate breakage.
>
> I'm travelling at the moment and won't be able to come with measurement
> before next month. But the performance degradation is obvious.
Ack, then I'll send a patch. Thanks for all the information.
> With the fix, the function is stackless:
(...)
> Without the fix, see below, __c_kernel_clock_getres() has to setup a stack
> in order to call __cvdso_clock_getres_common(), and in addition we see that
> __cvdso_clock_getres_common() is more or less the same size as
> __c_kernel_clock_getres() above, so time increase unquestionable.
(...)
> > I'll still try to get the stack initialization out of the vDSO.
> > It might bite us at any time in the future. As these options are meant
> > to prevent information leaks and the vDSO has no sensitive information in
> > the first place, we might as well filter them out.
>
> Well, from the first day we converted powerpc to C time vdso, we've done our
> best in order to keep vdso stackless. So I'm not sure it is worth dealing
> with the above. Indeed if keeping it as is helps us detect everytime a
> change jeoperdises the stackless approach, that's not bad.
I was not aware about the stacklessness. Then this should be reason enough.
We should get a better system to detect these additional stacks though.
I'll think about it a bit more.
Note: -finline-stringops=memset would also avoid the issues.
Thomas
Le 22/01/2026 à 12:41, Thomas Weißschuh a écrit :
> On Thu, Jan 22, 2026 at 12:31:32PM +0100, Christophe Leroy (CS GROUP) wrote:
>> Le 22/01/2026 à 12:07, Thomas Weißschuh a écrit :
>>> On Thu, Jan 22, 2026 at 11:58:04AM +0100, Christophe Leroy (CS GROUP) wrote:
>>>>
>>>>
>>>> Le 22/01/2026 à 11:49, Thomas Weißschuh a écrit :
>>>>> On Thu, Jan 22, 2026 at 11:27:43AM +0100, Christophe Leroy (CS GROUP) wrote:
>>>>>> 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@linutronix.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%7Cbd6434eab4334cea44fe08de59ab274e%7C8b87af7d86474dc78df45f69a2011bb5%7C0%7C0%7C639046788822130060%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=K7PlfBLHdNEBRgsPQ5aNBgu2v8DqDrhmzwoHrcOc5s8%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
>>>>>
>>>>> Thanks for the hint, no I can reproduce it, too.
>>>>>>
>>>>>> 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
>>>>>
>>>>> It seems the compiler decides to call memset(), which is not valid from the
>>>>> vDSO. We are are using -ffreestanding. Disabling CONFIG_INIT_STACK_ALL_ZERO
>>>>> fixes the issue. So I guess we should a) figure out why -ffreestanding does
>>>>> not seem to work here and b) exclude the vDSO from the stack initialization
>>>>> logic.
>>>>>
>>>>
>>>> Ah, ok.
>>>>
>>>> Reminds me commit b91c8c42ffdd ("lib/vdso: Force inlining of
>>>> __cvdso_clock_gettime_common()")
>>>
>>> Good pointer.
>>>
>>>> Problem fixed with:
>>>>
>>>> diff --git a/lib/vdso/gettimeofday.c b/lib/vdso/gettimeofday.c
>>>> index 95df0153f05ab..4399e143d43a5 100644
>>>> --- a/lib/vdso/gettimeofday.c
>>>> +++ b/lib/vdso/gettimeofday.c
>>>> @@ -421,7 +421,7 @@ static __maybe_unused __kernel_old_time_t
>>>> __cvdso_time(__kernel_old_time_t *time
>>>> #endif /* VDSO_HAS_TIME */
>>>>
>>>> #ifdef VDSO_HAS_CLOCK_GETRES
>>>> -static __maybe_unused
>>>> +static __always_inline
>>>> bool __cvdso_clock_getres_common(const struct vdso_time_data *vd, clockid_t
>>>> clock,
>>>> struct __kernel_timespec *res)
>>>> {
>>>
>>> Do you want to run the measurements for this one, too and submit a fix?
>>> This should get us past the immediate breakage.
>>
>> I'm travelling at the moment and won't be able to come with measurement
>> before next month. But the performance degradation is obvious.
>
> Ack, then I'll send a patch. Thanks for all the information.
>
>> With the fix, the function is stackless:
>
> (...)
>
>> Without the fix, see below, __c_kernel_clock_getres() has to setup a stack
>> in order to call __cvdso_clock_getres_common(), and in addition we see that
>> __cvdso_clock_getres_common() is more or less the same size as
>> __c_kernel_clock_getres() above, so time increase unquestionable.
>
> (...)
>
>>> I'll still try to get the stack initialization out of the vDSO.
>>> It might bite us at any time in the future. As these options are meant
>>> to prevent information leaks and the vDSO has no sensitive information in
>>> the first place, we might as well filter them out.
>>
>> Well, from the first day we converted powerpc to C time vdso, we've done our
>> best in order to keep vdso stackless. So I'm not sure it is worth dealing
>> with the above. Indeed if keeping it as is helps us detect everytime a
>> change jeoperdises the stackless approach, that's not bad.
>
> I was not aware about the stacklessness. Then this should be reason enough.
> We should get a better system to detect these additional stacks though.
> I'll think about it a bit more.
Well, that's only a "best effort", at the end we don't success in all
cases, refer commit 08c18b63d965 ("powerpc/vdso32: Add missing
_restgpr_31_x to fix build failure"), there are not enough volatile
registers for __c_kernel_clock_gettime(), part of this function sets up
a stack frame to save one non-volatile register and use it. But at least
for time we can keep flat functions that don't have to suffer the
overcost of saving volatile registers for calling subfunctions.
For __c_kernel_getrandom() that's different because it has to call
__arch_chacha20_blocks_nostack() so a stack frame is definitely needed
but at least we also avoid there to have multiple sub-function calls.
Christophe
Le 14/01/2026 à 08:26, Thomas Weißschuh a écrit :
> 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@linutronix.de>
Reviewed-by: Christophe Leroy (CS GROUP) <chleroy@kernel.org>
> ---
> 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(+)
>
> diff --git a/arch/powerpc/include/asm/vdso/gettimeofday.h b/arch/powerpc/include/asm/vdso/gettimeofday.h
> index ab3df12c8d94..8ea397e26ad0 100644
> --- a/arch/powerpc/include/asm/vdso/gettimeofday.h
> +++ b/arch/powerpc/include/asm/vdso/gettimeofday.h
> @@ -135,6 +135,8 @@ int __c_kernel_clock_gettime64(clockid_t clock, struct __kernel_timespec *ts,
> const struct vdso_time_data *vd);
> int __c_kernel_clock_getres(clockid_t clock_id, struct old_timespec32 *res,
> const struct vdso_time_data *vd);
> +int __c_kernel_clock_getres_time64(clockid_t clock_id, struct __kernel_timespec *res,
> + const struct vdso_time_data *vd);
> #endif
> int __c_kernel_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz,
> const struct vdso_time_data *vd);
> diff --git a/arch/powerpc/kernel/vdso/gettimeofday.S b/arch/powerpc/kernel/vdso/gettimeofday.S
> index 79c967212444..1c8e51691bf8 100644
> --- a/arch/powerpc/kernel/vdso/gettimeofday.S
> +++ b/arch/powerpc/kernel/vdso/gettimeofday.S
> @@ -103,6 +103,18 @@ V_FUNCTION_BEGIN(__kernel_clock_getres)
> cvdso_call __c_kernel_clock_getres
> V_FUNCTION_END(__kernel_clock_getres)
>
> +/*
> + * Exact prototype of clock_getres_time64()
> + *
> + * int __kernel_clock_getres(clockid_t clock_id, struct __timespec64 *res);
> + *
> + */
> +#ifndef __powerpc64__
> +V_FUNCTION_BEGIN(__kernel_clock_getres_time64)
> + cvdso_call __c_kernel_clock_getres_time64
> +V_FUNCTION_END(__kernel_clock_getres_time64)
> +#endif
> +
>
> /*
> * Exact prototype of time()
> diff --git a/arch/powerpc/kernel/vdso/vdso32.lds.S b/arch/powerpc/kernel/vdso/vdso32.lds.S
> index 72a1012b8a20..3f384a2526ae 100644
> --- a/arch/powerpc/kernel/vdso/vdso32.lds.S
> +++ b/arch/powerpc/kernel/vdso/vdso32.lds.S
> @@ -124,6 +124,7 @@ VERSION
> __kernel_clock_gettime;
> __kernel_clock_gettime64;
> __kernel_clock_getres;
> + __kernel_clock_getres_time64;
> __kernel_time;
> __kernel_get_tbfreq;
> __kernel_sync_dicache;
> diff --git a/arch/powerpc/kernel/vdso/vgettimeofday.c b/arch/powerpc/kernel/vdso/vgettimeofday.c
> index 6f5167d81af5..3c194e1ab562 100644
> --- a/arch/powerpc/kernel/vdso/vgettimeofday.c
> +++ b/arch/powerpc/kernel/vdso/vgettimeofday.c
> @@ -35,6 +35,12 @@ int __c_kernel_clock_getres(clockid_t clock_id, struct old_timespec32 *res,
> {
> return __cvdso_clock_getres_time32_data(vd, clock_id, res);
> }
> +
> +int __c_kernel_clock_getres_time64(clockid_t clock_id, struct __kernel_timespec *res,
> + const struct vdso_time_data *vd)
> +{
> + return __cvdso_clock_getres_data(vd, clock_id, res);
> +}
> #endif
>
> int __c_kernel_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz,
>
> ---
> base-commit: 0e55e7636697077abceb2301d7d2718d75c34389
> change-id: 20260113-vdso-powerpc-align-e8e93664da2b
>
> Best regards,
The following commit has been merged into the timers/vdso branch of tip:
Commit-ID: 759a1f97373f25770cf438d9fb5f2bddf4d77a54
Gitweb: https://git.kernel.org/tip/759a1f97373f25770cf438d9fb5f2bddf4d77a54
Author: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
AuthorDate: Wed, 14 Jan 2026 08:26:05 +01:00
Committer: Thomas Gleixner <tglx@kernel.org>
CommitterDate: Wed, 14 Jan 2026 14:57:39 +01:00
powerpc/vdso: Provide clock_getres_time64()
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@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Reviewed-by: Christophe Leroy (CS GROUP) <chleroy@kernel.org>
Link: https://patch.msgid.link/20260114-vdso-powerpc-align-v1-1-acf09373d568@linutronix.de
---
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(+)
diff --git a/arch/powerpc/include/asm/vdso/gettimeofday.h b/arch/powerpc/include/asm/vdso/gettimeofday.h
index ab3df12..8ea397e 100644
--- a/arch/powerpc/include/asm/vdso/gettimeofday.h
+++ b/arch/powerpc/include/asm/vdso/gettimeofday.h
@@ -135,6 +135,8 @@ int __c_kernel_clock_gettime64(clockid_t clock, struct __kernel_timespec *ts,
const struct vdso_time_data *vd);
int __c_kernel_clock_getres(clockid_t clock_id, struct old_timespec32 *res,
const struct vdso_time_data *vd);
+int __c_kernel_clock_getres_time64(clockid_t clock_id, struct __kernel_timespec *res,
+ const struct vdso_time_data *vd);
#endif
int __c_kernel_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz,
const struct vdso_time_data *vd);
diff --git a/arch/powerpc/kernel/vdso/gettimeofday.S b/arch/powerpc/kernel/vdso/gettimeofday.S
index 79c9672..1c8e516 100644
--- a/arch/powerpc/kernel/vdso/gettimeofday.S
+++ b/arch/powerpc/kernel/vdso/gettimeofday.S
@@ -103,6 +103,18 @@ V_FUNCTION_BEGIN(__kernel_clock_getres)
cvdso_call __c_kernel_clock_getres
V_FUNCTION_END(__kernel_clock_getres)
+/*
+ * Exact prototype of clock_getres_time64()
+ *
+ * int __kernel_clock_getres(clockid_t clock_id, struct __timespec64 *res);
+ *
+ */
+#ifndef __powerpc64__
+V_FUNCTION_BEGIN(__kernel_clock_getres_time64)
+ cvdso_call __c_kernel_clock_getres_time64
+V_FUNCTION_END(__kernel_clock_getres_time64)
+#endif
+
/*
* Exact prototype of time()
diff --git a/arch/powerpc/kernel/vdso/vdso32.lds.S b/arch/powerpc/kernel/vdso/vdso32.lds.S
index 72a1012..3f384a2 100644
--- a/arch/powerpc/kernel/vdso/vdso32.lds.S
+++ b/arch/powerpc/kernel/vdso/vdso32.lds.S
@@ -124,6 +124,7 @@ VERSION
__kernel_clock_gettime;
__kernel_clock_gettime64;
__kernel_clock_getres;
+ __kernel_clock_getres_time64;
__kernel_time;
__kernel_get_tbfreq;
__kernel_sync_dicache;
diff --git a/arch/powerpc/kernel/vdso/vgettimeofday.c b/arch/powerpc/kernel/vdso/vgettimeofday.c
index 6f5167d..3c194e1 100644
--- a/arch/powerpc/kernel/vdso/vgettimeofday.c
+++ b/arch/powerpc/kernel/vdso/vgettimeofday.c
@@ -35,6 +35,12 @@ int __c_kernel_clock_getres(clockid_t clock_id, struct old_timespec32 *res,
{
return __cvdso_clock_getres_time32_data(vd, clock_id, res);
}
+
+int __c_kernel_clock_getres_time64(clockid_t clock_id, struct __kernel_timespec *res,
+ const struct vdso_time_data *vd)
+{
+ return __cvdso_clock_getres_data(vd, clock_id, res);
+}
#endif
int __c_kernel_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz,© 2016 - 2026 Red Hat, Inc.