powerpc/pgtable: remove _PAGE_BIT_SWAP_TYPE for book3s

The swap type is simply stored in bits 0x1f of the swap pte.  Let's
simplify by just getting rid of _PAGE_BIT_SWAP_TYPE.  It's not like that
we can simply change it: _PAGE_SWP_SOFT_DIRTY would suddenly fall into
_RPAGE_RSV1, which isn't possible and would make the
BUILD_BUG_ON(_PAGE_HPTEFLAGS & _PAGE_SWP_SOFT_DIRTY) angry.

While at it, make it clearer which bit we're actually using for
_PAGE_SWP_SOFT_DIRTY by just using the proper define and introduce and use
SWP_TYPE_MASK.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: David Hildenbrand <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Don Dutile <[email protected]>
Cc: Gerald Schaefer <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Jann Horn <[email protected]>
Cc: Jason Gunthorpe <[email protected]>
Cc: John Hubbard <[email protected]>
Cc: "Kirill A. Shutemov" <[email protected]>
Cc: Liang Zhang <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: Nadav Amit <[email protected]>
Cc: Oded Gabbay <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Pedro Demarchi Gomes <[email protected]>
Cc: Peter Xu <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: Roman Gushchin <[email protected]>
Cc: Shakeel Butt <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Vasily Gorbik <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Will Deacon <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

arch/powerpc/include/asm/book3s/64/pgtable.h

@@ -13,7 +13,6 @@
 /*
  * Common bits between hash and Radix page table
  */
-#define _PAGE_BIT_SWAP_TYPE	0
 
 #define _PAGE_EXEC		0x00001 /* execute permission */
 #define _PAGE_WRITE		0x00002 /* write access allowed */
@@ -751,17 +750,16 @@ static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
 	 * Don't have overlapping bits with _PAGE_HPTEFLAGS	\
 	 * We filter HPTEFLAGS on set_pte.			\
 	 */							\
-	BUILD_BUG_ON(_PAGE_HPTEFLAGS & (0x1f << _PAGE_BIT_SWAP_TYPE)); \
+	BUILD_BUG_ON(_PAGE_HPTEFLAGS & SWP_TYPE_MASK); \
 	BUILD_BUG_ON(_PAGE_HPTEFLAGS & _PAGE_SWP_SOFT_DIRTY);	\
 	} while (0)
 
 #define SWP_TYPE_BITS 5
-#define __swp_type(x)		(((x).val >> _PAGE_BIT_SWAP_TYPE) \
-				& ((1UL << SWP_TYPE_BITS) - 1))
+#define SWP_TYPE_MASK		((1UL << SWP_TYPE_BITS) - 1)
+#define __swp_type(x)		((x).val & SWP_TYPE_MASK)
 #define __swp_offset(x)		(((x).val & PTE_RPN_MASK) >> PAGE_SHIFT)
 #define __swp_entry(type, offset)	((swp_entry_t) { \
-				((type) << _PAGE_BIT_SWAP_TYPE) \
-				| (((offset) << PAGE_SHIFT) & PTE_RPN_MASK)})
+				(type) | (((offset) << PAGE_SHIFT) & PTE_RPN_MASK)})
 /*
  * swp_entry_t must be independent of pte bits. We build a swp_entry_t from
  * swap type and offset we get from swap and convert that to pte to find a
@@ -774,7 +772,7 @@ static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
 #define __swp_entry_to_pmd(x)	(pte_pmd(__swp_entry_to_pte(x)))
 
 #ifdef CONFIG_MEM_SOFT_DIRTY
-#define _PAGE_SWP_SOFT_DIRTY   (1UL << (SWP_TYPE_BITS + _PAGE_BIT_SWAP_TYPE))
+#define _PAGE_SWP_SOFT_DIRTY	_PAGE_NON_IDEMPOTENT
 #else
 #define _PAGE_SWP_SOFT_DIRTY	0UL
 #endif /* CONFIG_MEM_SOFT_DIRTY */