Hi Michael,
Le 24/09/2020 à 15:17, Christophe Leroy a écrit :
Hi Michael
Le 17/09/2020 à 14:33, Michael Ellerman a écrit :
Hi Christophe,
Christophe Leroy <christophe.le...@csgroup.eu> writes:
Hi Michael,
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.
As you can see from the instruction dump we have jumped into the weeds
somewhere.
We also had the report from the kbuild robot about rela.opd being
discarded, which I think is indicative of a bigger problem. ie. we don't
process relocations for the VDSO, but opds require relocations (they
contain an absolute pointer).
I thought we could get away with that, because the VDSO entry points
aren't proper functions (so they don't have opds), and I didn't think
we'd be calling via function pointers in the VDSO code (which would
require opds). But seems something is not working right.
Sorry I haven't got back to you with those details. Things are a bit of
a mess inside IBM at the moment (always?), and I've been trying to get
everything done before I take a holiday next week.
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 ?
Christophe
I tested with both ppc64_defconfig and pseries_defconfig.
The only problem I got is with getcpu, which segfaults but both before and after applying my series,
so I guess this is unrelated.
Not sure we can pay too much attention to the exact measurement as it is a ppc64 QEMU running on a
x86 Linux which is running in a Virtual Box on a x86 windows Laptop, but at least it works:
Without the series:
clock-getres-monotonic: vdso: 389 nsec/call
clock-gettime-monotonic: vdso: 781 nsec/call
clock-getres-monotonic-coarse: vdso: 13715 nsec/call
clock-gettime-monotonic-coarse: vdso: 312 nsec/call
clock-getres-monotonic-raw: vdso: 13589 nsec/call
clock-getres-tai: vdso: 13827 nsec/call
clock-gettime-tai: vdso: 14846 nsec/call
clock-getres-boottime: vdso: 13596 nsec/call
clock-gettime-boottime: vdso: 14758 nsec/call
clock-getres-realtime: vdso: 327 nsec/call
clock-gettime-realtime: vdso: 717 nsec/call
clock-getres-realtime-coarse: vdso: 14102 nsec/call
clock-gettime-realtime-coarse: vdso: 299 nsec/call
gettimeofday: vdso: 771 nsec/call
With the series:
clock-getres-monotonic: vdso: 350 nsec/call
clock-gettime-monotonic: vdso: 726 nsec/call
clock-getres-monotonic-coarse: vdso: 356 nsec/call
clock-gettime-monotonic-coarse: vdso: 423 nsec/call
clock-getres-monotonic-raw: vdso: 349 nsec/call
clock-getres-tai: vdso: 419 nsec/call
clock-gettime-tai: vdso: 724 nsec/call
clock-getres-boottime: vdso: 352 nsec/call
clock-gettime-boottime: vdso: 752 nsec/call
clock-getres-realtime: vdso: 351 nsec/call
clock-gettime-realtime: vdso: 733 nsec/call
clock-getres-realtime-coarse: vdso: 356 nsec/call
clock-gettime-realtime-coarse: vdso: 367 nsec/call
gettimeofday: vdso: 796 nsec/call
Thanks
Christophe
