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| author | Dmitry Safonov <dima@arista.com> | 2021-03-31 19:48:46 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-05-12 09:39:57 +0300 |
| commit | f486ef7e762e7b38482c27ee833918bfa528bf35 (patch) | |
| tree | 3f986e1504b3149c49899945f5ddb2b4d1d28d94 /arch/powerpc/include/asm/mmu_context.h | |
| parent | 43aa1cfeebf447a263682379e3de57c1673ad918 (diff) | |
| download | linux-f486ef7e762e7b38482c27ee833918bfa528bf35.tar.xz | |
powerpc/vdso: Separate vvar vma from vdso
commit 1c4bce6753857dc409a0197342d18764e7f4b741 upstream.
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!
[1]: https://github.com/checkpoint-restore/criu/issues/1417
Cc: stable@vger.kernel.org # v5.11
Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Tested-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com> # vDSO parts.
Acked-by: Andrei Vagin <avagin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/f401eb1ebc0bfc4d8f0e10dc8e525fd409eb68e2.1617209142.git.christophe.leroy@csgroup.eu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch/powerpc/include/asm/mmu_context.h')
| -rw-r--r-- | arch/powerpc/include/asm/mmu_context.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/powerpc/include/asm/mmu_context.h b/arch/powerpc/include/asm/mmu_context.h index 652ce85f9410..4bc45d3ed8b0 100644 --- a/arch/powerpc/include/asm/mmu_context.h +++ b/arch/powerpc/include/asm/mmu_context.h @@ -263,7 +263,7 @@ extern void arch_exit_mmap(struct mm_struct *mm); static inline void arch_unmap(struct mm_struct *mm, unsigned long start, unsigned long end) { - unsigned long vdso_base = (unsigned long)mm->context.vdso - PAGE_SIZE; + unsigned long vdso_base = (unsigned long)mm->context.vdso; if (start <= vdso_base && vdso_base < end) mm->context.vdso = NULL; |