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:

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Hi Thomas,

Le 22/01/2026 à 10:50, Thomas Weißschuh a écrit :

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Hi Alexander,

On Thu, Jan 22, 2026 at 09:39:09AM +0000, Sverdlin, Alexander wrote:

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Hi Thomas, Christophe,

On Wed, 2026-01-14 at 08:26 +0100, Thomas Weißschuh wrote:

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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 <redacted>

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!

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Does it ring any bells? What could I try/test?

Not immediately, but I'll look into it.

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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.

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   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