linux-stable.git/arch/powerpc/kernel/vdso.c, branch linux-5.11.y

powerpc/vdso: Separate vvar vma from vdso

2021-05-12T06:37:33+00:00

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 
Signed-off-by: Christophe Leroy 
Tested-by: Christophe Leroy 
Reviewed-by: Vincenzo Frascino  # vDSO parts.
Acked-by: Andrei Vagin 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/f401eb1ebc0bfc4d8f0e10dc8e525fd409eb68e2.1617209142.git.christophe.leroy@csgroup.eu
Signed-off-by: Greg Kroah-Hartman

powerpc/vdso: Remove DBG()

2020-12-03T14:01:19+00:00

DBG() is not used anymore. Remove it.

Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/e11a9b50e709f197bb3aa2ed1d80d2dee8714afc.1601197618.git.christophe.leroy@csgroup.eu

powerpc/vdso: Remove vdso_ready

2020-12-03T14:01:19+00:00

There is no way to get out of vdso_init() prematuraly anymore.

Remove vdso_ready as it will always be 1.

Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/0e1e18c6329b848aa3edeeba76509b4d76182e7d.1601197618.git.christophe.leroy@csgroup.eu

powerpc/vdso: Remove vdso_setup()

2020-12-03T14:01:19+00:00

vdso_fixup_features() cannot fail anymore and that's
the only function called by vdso_setup().

vdso_setup() has become trivial and can be removed.

Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/11522eec6140f510a8c89c63cbb739277d097fdc.1601197618.git.christophe.leroy@csgroup.eu

powerpc/vdso: Remove lib32_elfinfo and lib64_elfinfo

2020-12-03T14:01:19+00:00

lib32_elfinfo and lib64_elfinfo are not used anymore, remove them.

Also remove vdso32_kbase and vdso64_kbase while removing the
last use.

Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/01ac65abf22f0428f8f764525a7d84459c54d806.1601197618.git.christophe.leroy@csgroup.eu

powerpc/vdso: Remove symbol section information in struct lib32/64_elfinfo

2020-12-03T14:01:18+00:00

The members related to the symbol section in struct lib32_elfinfo and
struct lib64_elfinfo are not used anymore, removed them.

Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/b779e5b7cc0354e2f87fd407fe5b02f4a8a73825.1601197618.git.christophe.leroy@csgroup.eu

powerpc/vdso: Remove unused text member in struct lib32/64_elfinfo

2020-12-03T14:01:18+00:00

The text member in struct lib32_elfinfo and struct lib64_elfinfo
is not used, remove it.

Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/f53dcc9bb1946a7854d15b34d03d3d2e2003848c.1601197618.git.christophe.leroy@csgroup.eu

powerpc/vdso: Remove vdso_patches[] and associated functions

2020-12-03T14:01:18+00:00

vdso_patches[] is now empty, remove it and remove
all functions that depends on it.

Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/27d75debd6e4ddeaffe1d66ffed1e7526684a004.1601197618.git.christophe.leroy@csgroup.eu

powerpc/vdso: Remove runtime generated sigtramp offsets

2020-12-03T14:01:18+00:00

Signal trampoline offsets are now generated at buildtime.

Runtime generated offsets are not used anymore, remove them.

Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/7c192d35a437151837cf4c48aeccb42380d6daac.1601197618.git.christophe.leroy@csgroup.eu

powerpc/vdso: Remove __kernel_datapage_offset

2020-12-03T14:01:18+00:00

__kernel_datapage_offset is not used anymore, remove it.

Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/ddb5c746bec4e1a026d7c85243213a1876ef844f.1601197618.git.christophe.leroy@csgroup.eu