[RFC PATCH 4/9] powerpc/mm/book3s-64: Move _PAGE_PRESENT to the most significant bit

[Paul Mackerras <paulus@samba.org>]

This changes _PAGE_PRESENT for 64-bit Book 3S processors from 0x2 to
0x8000_0000_0000_0000, because that is where PowerISA v3.0 CPUs in
radix mode will expect to find it.

Signed-off-by: Paul Mackerras <paulus@samba.org>
---
 arch/powerpc/include/asm/book3s/64/hash-64k.h | 10 +++++-----
 arch/powerpc/include/asm/book3s/64/hash.h     |  5 +++--
 arch/powerpc/mm/mmu_decl.h                    |  2 +-
 arch/powerpc/mm/pgtable_64.c                  |  2 +-
 4 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/arch/powerpc/include/asm/book3s/64/hash-64k.h b/arch/powerpc/include/asm/book3s/64/hash-64k.h
index a8c4c2a..ed390e1 100644
--- a/arch/powerpc/include/asm/book3s/64/hash-64k.h
+++ b/arch/powerpc/include/asm/book3s/64/hash-64k.h
@@ -210,30 +210,30 @@ static inline char *get_hpte_slot_array(pmd_t *pmdp)
 /*
  * The linux hugepage PMD now include the pmd entries followed by the address
  * to the stashed pgtable_t. The stashed pgtable_t contains the hpte bits.
- * [ 1 bit secondary | 3 bit hidx | 1 bit valid | 000]. We use one byte per
+ * [ 000 | 1 bit secondary | 3 bit hidx | 1 bit valid]. We use one byte per
  * each HPTE entry. With 16MB hugepage and 64K HPTE we need 256 entries and
  * with 4K HPTE we need 4096 entries. Both will fit in a 4K pgtable_t.
  *
- * The last three bits are intentionally left to zero. This memory location
+ * The top three bits are intentionally left as zero. This memory location
  * are also used as normal page PTE pointers. So if we have any pointers
  * left around while we collapse a hugepage, we need to make sure
  * _PAGE_PRESENT bit of that is zero when we look at them
  */
 static inline unsigned int hpte_valid(unsigned char *hpte_slot_array, int index)
 {
-	return (hpte_slot_array[index] >> 3) & 0x1;
+	return hpte_slot_array[index] & 0x1;
 }
 
 static inline unsigned int hpte_hash_index(unsigned char *hpte_slot_array,
 					   int index)
 {
-	return hpte_slot_array[index] >> 4;
+	return hpte_slot_array[index] >> 1;
 }
 
 static inline void mark_hpte_slot_valid(unsigned char *hpte_slot_array,
 					unsigned int index, unsigned int hidx)
 {
-	hpte_slot_array[index] = hidx << 4 | 0x1 << 3;
+	hpte_slot_array[index] = (hidx << 1) | 0x1;
 }
 
 /*
diff --git a/arch/powerpc/include/asm/book3s/64/hash.h b/arch/powerpc/include/asm/book3s/64/hash.h
index fcab33f..72ea557 100644
--- a/arch/powerpc/include/asm/book3s/64/hash.h
+++ b/arch/powerpc/include/asm/book3s/64/hash.h
@@ -14,7 +14,6 @@
  * combinations that newer processors provide but we currently don't.
  */
 #define _PAGE_PTE		0x00001	/* distinguishes PTEs from pointers */
-#define _PAGE_PRESENT		0x00002 /* software: pte contains a translation */
 #define _PAGE_BIT_SWAP_TYPE	2
 #define _PAGE_USER		0x00004 /* page may be accessed by userspace */
 #define _PAGE_EXEC		0x00008 /* execute permission */
@@ -39,6 +38,8 @@
 #define _PAGE_SOFT_DIRTY	0x00000
 #endif
 
+#define _PAGE_PRESENT		(1ul << 63)	/* pte contains a translation */
+
 /*
  * We need to differentiate between explicit huge page and THP huge
  * page, since THP huge page also need to track real subpage details
@@ -399,7 +400,7 @@ static inline int pte_protnone(pte_t pte)
 
 static inline int pte_present(pte_t pte)
 {
-	return pte_val(pte) & _PAGE_PRESENT;
+	return !!(pte_val(pte) & _PAGE_PRESENT);
 }
 
 /* Conversion functions: convert a page and protection to a page entry,
diff --git a/arch/powerpc/mm/mmu_decl.h b/arch/powerpc/mm/mmu_decl.h
index 9f58ff4..92da107 100644
--- a/arch/powerpc/mm/mmu_decl.h
+++ b/arch/powerpc/mm/mmu_decl.h
@@ -110,7 +110,7 @@ extern unsigned long Hash_size, Hash_mask;
 #endif /* CONFIG_PPC32 */
 
 #ifdef CONFIG_PPC64
-extern int map_kernel_page(unsigned long ea, unsigned long pa, int flags);
+extern int map_kernel_page(unsigned long ea, unsigned long pa, pgprot_t flags);
 #endif /* CONFIG_PPC64 */
 
 extern unsigned long ioremap_bot;
diff --git a/arch/powerpc/mm/pgtable_64.c b/arch/powerpc/mm/pgtable_64.c
index 950c572..c50d9a2 100644
--- a/arch/powerpc/mm/pgtable_64.c
+++ b/arch/powerpc/mm/pgtable_64.c
@@ -88,7 +88,7 @@ static __ref void *early_alloc_pgtable(unsigned long size)
  * map_kernel_page adds an entry to the ioremap page table
  * and adds an entry to the HPT, possibly bolting it
  */
-int map_kernel_page(unsigned long ea, unsigned long pa, int flags)
+int map_kernel_page(unsigned long ea, unsigned long pa, pgprot_t flags)
 {
 	pgd_t *pgdp;
 	pud_t *pudp;
-- 
2.5.0