C vdso

[Michael Ellerman]

Christophe Leroy <christophe.leroy at csgroup.eu> writes:
> Le 24/09/2020 à 15:17, Christophe Leroy a écrit :
>> Le 17/09/2020 à 14:33, Michael Ellerman a écrit :
>>> Christophe Leroy <christophe.leroy at csgroup.eu> writes:
>>>>
>>>> What is the status with the generic C vdso merge ?
>>>> In some mail, you mentionned having difficulties getting it working on
>>>> ppc64, any progress ? What's the problem ? Can I help ?
>>>
>>> Yeah sorry I was hoping to get time to work on it but haven't been able
>>> to.
>>>
>>> It's causing crashes on ppc64 ie. big endian.
...
>> 
>> Can you tell what defconfig you are using ? I have been able to setup a full glibc PPC64 cross 
>> compilation chain and been able to test it under QEMU with success, using Nathan's vdsotest tool.
>
> What config are you using ?

ppc64_defconfig + guest.config

Or pseries_defconfig.

I'm using Ubuntu GCC 9.3.0 mostly, but it happens with other toolchains too.

At a minimum we're seeing relocations in the output, which is a problem:

  $ readelf -r build\~/arch/powerpc/kernel/vdso64/vdso64.so
  
  Relocation section '.rela.dyn' at offset 0x12a8 contains 8 entries:
    Offset          Info           Type           Sym. Value    Sym. Name + Addend
  000000001368  000000000016 R_PPC64_RELATIVE                     7c0
  000000001370  000000000016 R_PPC64_RELATIVE                     9300
  000000001380  000000000016 R_PPC64_RELATIVE                     970
  000000001388  000000000016 R_PPC64_RELATIVE                     9300
  000000001398  000000000016 R_PPC64_RELATIVE                     a90
  0000000013a0  000000000016 R_PPC64_RELATIVE                     9300
  0000000013b0  000000000016 R_PPC64_RELATIVE                     b20
  0000000013b8  000000000016 R_PPC64_RELATIVE                     9300



cheers