On Wed, Mar 31, 2021 at 04:48:46PM +0000, Christophe Leroy wrote: > From: Dmitry Safonov <[email protected]> > > Since commit 511157ab641e ("powerpc/vdso: Move vdso datapage up front") > VVAR page is in front of the VDSO area. In result it breaks CRIU > (Checkpoint Restore In Userspace) [1], where CRIU expects that "[vdso]" > from /proc/../maps points at ELF/vdso image, rather than at VVAR data page. > Laurent made a patch to keep CRIU working (by reading aux vector). > But I think it still makes sence to separate two mappings into different > VMAs. It will also make ppc64 less "special" for userspace and as > a side-bonus will make VVAR page un-writable by debugger (which previously > would COW page and can be unexpected). > > I opportunistically Cc stable on it: I understand that usually such > stuff isn't a stable material, but that will allow us in CRIU have > one workaround less that is needed just for one release (v5.11) on > one platform (ppc64), which we otherwise have to maintain. > I wouldn't go as far as to say that the commit 511157ab641e is ABI > regression as no other userspace got broken, but I'd really appreciate > if it gets backported to v5.11 after v5.12 is released, so as not > to complicate already non-simple CRIU-vdso code. Thanks! > > Cc: Andrei Vagin <[email protected]>
Acked-by: Andrei Vagin <[email protected]> > Cc: Andy Lutomirski <[email protected]> > Cc: Benjamin Herrenschmidt <[email protected]> > Cc: Christophe Leroy <[email protected]> > Cc: Laurent Dufour <[email protected]> > Cc: Michael Ellerman <[email protected]> > Cc: Paul Mackerras <[email protected]> > Cc: [email protected] > Cc: [email protected] # v5.11 > [1]: https://github.com/checkpoint-restore/criu/issues/1417 > Signed-off-by: Dmitry Safonov <[email protected]> > Tested-by: Christophe Leroy <[email protected]> > Signed-off-by: Christophe Leroy <[email protected]>
