ISA v3.1 does not support the SAO storage control attribute required to
implement PROT_SAO. PROT_SAO was used by specialised system software
(Lx86) that has been discontinued for about 7 years, and is not thought
to be used elsewhere, so removal should not cause problems.
We rather remove it than keep support for older processors, because
live migrating guest partitions to newer processors may not be possible
if SAO is in use (or worse allowed with silent races).
- PROT_SAO stays in the uapi header so code using it would still build.
- arch_validate_prot() is removed, the generic version rejects PROT_SAO
so applications would get a failure at mmap() time.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Drop KVM change for the time being]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200703011958.1166620-3-npiggin@gmail.com
PROT_SAO is a powerpc-specific flag to mmap(), and we rely on arch
specific logic to allow it to be passed to mmap().
Add a small test to ensure mmap() accepts PROT_SAO. We don't have a good
way to test that it actually causes the mapping to be created with the
right flags, so for now we just touch the mapping so it's faulted in. In
future we might be able to do something better.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
