powerpc/64s: Remove PROT_SAO support

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

1 files changed, 0 insertions, 4 deletions

diff --git a/mm/ksm.c b/mm/ksm.c
index 4102034cd55a..d1cfa18689b5 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -2452,10 +2452,6 @@ int ksm_madvise(struct vm_area_struct *vma, unsigned long start,
 		if (vma_is_dax(vma))
 			return 0;
 
-#ifdef VM_SAO
-		if (*vm_flags & VM_SAO)
-			return 0;
-#endif
 #ifdef VM_SPARC_ADI
 		if (*vm_flags & VM_SPARC_ADI)
 			return 0;