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

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Message-ID: <f45316f65a46da638b3c6aa69effd8980e6677b9.camel@siemens.com>
Date: Thu, 22 Jan 2026 09:39:09 +0000
From: "Sverdlin, Alexander" <alexander.sverdlin@...mens.com>
To: "thomas.weissschuh@...utronix.de" <thomas.weissschuh@...utronix.de>,
	"npiggin@...il.com" <npiggin@...il.com>, "luto@...nel.org" <luto@...nel.org>,
	"chleroy@...nel.org" <chleroy@...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>
CC: "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, 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

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