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Subject[PATCH 4.8 113/125] powerpc: Fix usage of _PAGE_RO in hugepage
Date
4.8-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Christophe Leroy <christophe.leroy@c-s.fr>

commit 6b8cb66a6a7cc182b47da6a0a1d4e5da324c0695 upstream.

On some CPUs like the 8xx, _PAGE_RW hence _PAGE_WRITE is defined
as 0 and _PAGE_RO has to be set when a page is not writable

_PAGE_RO is defined by default in pte-common.h, however BOOK3S/64
doesn't include that file so _PAGE_RO has to be defined explicitly
in book3s/64/pgtable.h

Fixes: a7b9f671f2d14 ("powerpc32: adds handling of _PAGE_RO")
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/powerpc/include/asm/book3s/64/pgtable.h | 2 ++
arch/powerpc/mm/hugetlbpage.c | 7 +++++++
2 files changed, 9 insertions(+)

--- a/arch/powerpc/include/asm/book3s/64/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
@@ -6,6 +6,8 @@
*/
#define _PAGE_BIT_SWAP_TYPE 0

+#define _PAGE_RO 0
+
#define _PAGE_EXEC 0x00001 /* execute permission */
#define _PAGE_WRITE 0x00002 /* write access allowed */
#define _PAGE_READ 0x00004 /* read access allowed */
--- a/arch/powerpc/mm/hugetlbpage.c
+++ b/arch/powerpc/mm/hugetlbpage.c
@@ -1019,8 +1019,15 @@ int gup_hugepte(pte_t *ptep, unsigned lo

pte = READ_ONCE(*ptep);
mask = _PAGE_PRESENT | _PAGE_READ;
+
+ /*
+ * On some CPUs like the 8xx, _PAGE_RW hence _PAGE_WRITE is defined
+ * as 0 and _PAGE_RO has to be set when a page is not writable
+ */
if (write)
mask |= _PAGE_WRITE;
+ else
+ mask |= _PAGE_RO;

if ((pte_val(pte) & mask) != mask)
return 0;

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