mm/hugetlb: add more arch-defined huge_pte functions

Commit abf09bed3cce ("s390/mm: implement software dirty bits")
introduced another difference in the pte layout vs.  the pmd layout on
s390, thoroughly breaking the s390 support for hugetlbfs.  This requires
replacing some more pte_xxx functions in mm/hugetlbfs.c with a
huge_pte_xxx version.

This patch introduces those huge_pte_xxx functions and their generic
implementation in asm-generic/hugetlb.h, which will now be included on
all architectures supporting hugetlbfs apart from s390.  This change
will be a no-op for those architectures.

[akpm@linux-foundation.org: fix warning]
Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Hillf Danton <dhillf@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.cz>	[for !s390 parts]
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 96 insertions, 57 deletions

diff --git a/arch/s390/include/asm/hugetlb.h b/arch/s390/include/asm/hugetlb.h
index 593753ee07f3..bd90359d6d22 100644
--- a/arch/s390/include/asm/hugetlb.h
+++ b/arch/s390/include/asm/hugetlb.h
@@ -114,7 +114,7 @@ static inline pte_t huge_ptep_get_and_clear(struct mm_struct *mm,
 #define huge_ptep_set_wrprotect(__mm, __addr, __ptep)			\
 ({									\
 	pte_t __pte = huge_ptep_get(__ptep);				\
-	if (pte_write(__pte)) {						\
+	if (huge_pte_write(__pte)) {					\
 		huge_ptep_invalidate(__mm, __addr, __ptep);		\
 		set_huge_pte_at(__mm, __addr, __ptep,			\
 				huge_pte_wrprotect(__pte));		\
@@ -127,4 +127,58 @@ static inline void huge_ptep_clear_flush(struct vm_area_struct *vma,
 	huge_ptep_invalidate(vma->vm_mm, address, ptep);
 }
 
+static inline pte_t mk_huge_pte(struct page *page, pgprot_t pgprot)
+{
+	pte_t pte;
+	pmd_t pmd;
+
+	pmd = mk_pmd_phys(page_to_phys(page), pgprot);
+	pte_val(pte) = pmd_val(pmd);
+	return pte;
+}
+
+static inline int huge_pte_write(pte_t pte)
+{
+	pmd_t pmd;
+
+	pmd_val(pmd) = pte_val(pte);
+	return pmd_write(pmd);
+}
+
+static inline int huge_pte_dirty(pte_t pte)
+{
+	/* No dirty bit in the segment table entry. */
+	return 0;
+}
+
+static inline pte_t huge_pte_mkwrite(pte_t pte)
+{
+	pmd_t pmd;
+
+	pmd_val(pmd) = pte_val(pte);
+	pte_val(pte) = pmd_val(pmd_mkwrite(pmd));
+	return pte;
+}
+
+static inline pte_t huge_pte_mkdirty(pte_t pte)
+{
+	/* No dirty bit in the segment table entry. */
+	return pte;
+}
+
+static inline pte_t huge_pte_modify(pte_t pte, pgprot_t newprot)
+{
+	pmd_t pmd;
+
+	pmd_val(pmd) = pte_val(pte);
+	pte_val(pte) = pmd_val(pmd_modify(pmd, newprot));
+	return pte;
+}
+
+static inline void huge_pte_clear(struct mm_struct *mm, unsigned long addr,
+				  pte_t *ptep)
+{
+	pmd_clear((pmd_t *) ptep);
+}
+
 #endif /* _ASM_S390_HUGETLB_H */
diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h
index 4a64c0e5428f..b4622915bd15 100644
--- a/arch/s390/include/asm/pgtable.h
+++ b/arch/s390/include/asm/pgtable.h
@@ -424,6 +424,13 @@ extern unsigned long MODULES_END;
 #define __S110	PAGE_RW
 #define __S111	PAGE_RW
 
+/*
+ * Segment entry (large page) protection definitions.
+ */
+#define SEGMENT_NONE	__pgprot(_HPAGE_TYPE_NONE)
+#define SEGMENT_RO	__pgprot(_HPAGE_TYPE_RO)
+#define SEGMENT_RW	__pgprot(_HPAGE_TYPE_RW)
+
 static inline int mm_exclusive(struct mm_struct *mm)
 {
 	return likely(mm == current->active_mm &&
@@ -914,26 +921,6 @@ static inline pte_t pte_mkspecial(pte_t pte)
 #ifdef CONFIG_HUGETLB_PAGE
 static inline pte_t pte_mkhuge(pte_t pte)
 {
-	/*
-	 * PROT_NONE needs to be remapped from the pte type to the ste type.
-	 * The HW invalid bit is also different for pte and ste. The pte
-	 * invalid bit happens to be the same as the ste _SEGMENT_ENTRY_LARGE
-	 * bit, so we don't have to clear it.
-	 */
-	if (pte_val(pte) & _PAGE_INVALID) {
-		if (pte_val(pte) & _PAGE_SWT)
-			pte_val(pte) |= _HPAGE_TYPE_NONE;
-		pte_val(pte) |= _SEGMENT_ENTRY_INV;
-	}
-	/*
-	 * Clear SW pte bits, there are no SW bits in a segment table entry.
-	 */
-	pte_val(pte) &= ~(_PAGE_SWT | _PAGE_SWX | _PAGE_SWC |
-			  _PAGE_SWR | _PAGE_SWW);
-	/*
-	 * Also set the change-override bit because we don't need dirty bit
-	 * tracking for hugetlbfs pages.
-	 */
 	pte_val(pte) |= (_SEGMENT_ENTRY_LARGE | _SEGMENT_ENTRY_CO);
 	return pte;
 }
@@ -1278,31 +1265,7 @@ static inline void __pmd_idte(unsigned long address, pmd_t *pmdp)
 	}
 }
 
-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
-
-#define SEGMENT_NONE	__pgprot(_HPAGE_TYPE_NONE)
-#define SEGMENT_RO	__pgprot(_HPAGE_TYPE_RO)
-#define SEGMENT_RW	__pgprot(_HPAGE_TYPE_RW)
-
-#define __HAVE_ARCH_PGTABLE_DEPOSIT
-extern void pgtable_trans_huge_deposit(struct mm_struct *mm, pgtable_t pgtable);
-
-#define __HAVE_ARCH_PGTABLE_WITHDRAW
-extern pgtable_t pgtable_trans_huge_withdraw(struct mm_struct *mm);
-
-static inline int pmd_trans_splitting(pmd_t pmd)
-{
-	return pmd_val(pmd) & _SEGMENT_ENTRY_SPLIT;
-}
-
-static inline void set_pmd_at(struct mm_struct *mm, unsigned long addr,
-			      pmd_t *pmdp, pmd_t entry)
-{
-	if (!(pmd_val(entry) & _SEGMENT_ENTRY_INV) && MACHINE_HAS_EDAT1)
-		pmd_val(entry) |= _SEGMENT_ENTRY_CO;
-	*pmdp = entry;
-}
-
+#if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLB_PAGE)
 static inline unsigned long massage_pgprot_pmd(pgprot_t pgprot)
 {
 	/*
@@ -1323,10 +1286,11 @@ static inline pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot)
 	return pmd;
 }
 
-static inline pmd_t pmd_mkhuge(pmd_t pmd)
+static inline pmd_t mk_pmd_phys(unsigned long physpage, pgprot_t pgprot)
 {
-	pmd_val(pmd) |= _SEGMENT_ENTRY_LARGE;
-	return pmd;
+	pmd_t __pmd;
+	pmd_val(__pmd) = physpage + massage_pgprot_pmd(pgprot);
+	return __pmd;
 }
 
 static inline pmd_t pmd_mkwrite(pmd_t pmd)
@@ -1336,6 +1300,34 @@ static inline pmd_t pmd_mkwrite(pmd_t pmd)
 		pmd_val(pmd) &= ~_SEGMENT_ENTRY_RO;
 	return pmd;
 }
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLB_PAGE */
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+
+#define __HAVE_ARCH_PGTABLE_DEPOSIT
+extern void pgtable_trans_huge_deposit(struct mm_struct *mm, pgtable_t pgtable);
+
+#define __HAVE_ARCH_PGTABLE_WITHDRAW
+extern pgtable_t pgtable_trans_huge_withdraw(struct mm_struct *mm);
+
+static inline int pmd_trans_splitting(pmd_t pmd)
+{
+	return pmd_val(pmd) & _SEGMENT_ENTRY_SPLIT;
+}
+
+static inline void set_pmd_at(struct mm_struct *mm, unsigned long addr,
+			      pmd_t *pmdp, pmd_t entry)
+{
+	if (!(pmd_val(entry) & _SEGMENT_ENTRY_INV) && MACHINE_HAS_EDAT1)
+		pmd_val(entry) |= _SEGMENT_ENTRY_CO;
+	*pmdp = entry;
+}
+
+static inline pmd_t pmd_mkhuge(pmd_t pmd)
+{
+	pmd_val(pmd) |= _SEGMENT_ENTRY_LARGE;
+	return pmd;
+}
 
 static inline pmd_t pmd_wrprotect(pmd_t pmd)
 {
@@ -1432,13 +1424,6 @@ static inline void pmdp_set_wrprotect(struct mm_struct *mm,
 	}
 }
 
-static inline pmd_t mk_pmd_phys(unsigned long physpage, pgprot_t pgprot)
-{
-	pmd_t __pmd;
-	pmd_val(__pmd) = physpage + massage_pgprot_pmd(pgprot);
-	return __pmd;
-}
-
 #define pfn_pmd(pfn, pgprot)	mk_pmd_phys(__pa((pfn) << PAGE_SHIFT), (pgprot))
 #define mk_pmd(page, pgprot)	pfn_pmd(page_to_pfn(page), (pgprot))
 
diff --git a/arch/s390/mm/hugetlbpage.c b/arch/s390/mm/hugetlbpage.c
index 532525ec88c1..121089d57802 100644
--- a/arch/s390/mm/hugetlbpage.c
+++ b/arch/s390/mm/hugetlbpage.c
@@ -39,7 +39,7 @@ int arch_prepare_hugepage(struct page *page)
 	if (!ptep)
 		return -ENOMEM;
 
-	pte = mk_pte(page, PAGE_RW);
+	pte_val(pte) = addr;
 	for (i = 0; i < PTRS_PER_PTE; i++) {
 		set_pte_at(&init_mm, addr + i * PAGE_SIZE, ptep + i, pte);
 		pte_val(pte) += PAGE_SIZE;