sparc64: Support transparent huge pages.

This is relatively easy since PMD's now cover exactly 4MB of memory.

Our PMD entries are 32-bits each, so we use a special encoding.  The
lowest bit, PMD_ISHUGE, determines the interpretation.  This is possible
because sparc64's page tables are purely software entities so we can use
whatever encoding scheme we want.  We just have to make the TLB miss
assembler page table walkers aware of the layout.

set_pmd_at() works much like set_pte_at() but it has to operate in two
page from a table of non-huge PTEs, so we have to queue up TLB flushes
based upon what mappings are valid in the PTE table.  In the second regime
we are going from huge-page to non-huge-page, and in that case we need
only queue up a single TLB flush to push out the huge page mapping.

We still have 5 bits remaining in the huge PMD encoding so we can very
likely support any new pieces of THP state tracking that might get added
in the future.

With lots of help from Johannes Weiner.

Signed-off-by: David S. Miller <davem@davemloft.net>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 171 insertions, 6 deletions

diff --git a/arch/sparc/include/asm/pgtable_64.h b/arch/sparc/include/asm/pgtable_64.h
index af3cd7a9e9a..95515f1e7ce 100644
--- a/arch/sparc/include/asm/pgtable_64.h
+++ b/arch/sparc/include/asm/pgtable_64.h
@@ -63,10 +63,31 @@
 #error Page table parameters do not cover virtual address space properly.
 #endif
 
+#if (PMD_SHIFT != HPAGE_SHIFT)
+#error PMD_SHIFT must equal HPAGE_SHIFT for transparent huge pages.
+#endif
+
 /* PMDs point to PTE tables which are 4K aligned.  */
 #define PMD_PADDR	_AC(0xfffffffe,UL)
 #define PMD_PADDR_SHIFT	_AC(11,UL)
 
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+#define PMD_ISHUGE	_AC(0x00000001,UL)
+
+/* This is the PMD layout when PMD_ISHUGE is set.  With 4MB huge
+ * pages, this frees up a bunch of bits in the layout that we can
+ * use for the protection settings and software metadata.
+ */
+#define PMD_HUGE_PADDR		_AC(0xfffff800,UL)
+#define PMD_HUGE_PROTBITS	_AC(0x000007ff,UL)
+#define PMD_HUGE_PRESENT	_AC(0x00000400,UL)
+#define PMD_HUGE_WRITE		_AC(0x00000200,UL)
+#define PMD_HUGE_DIRTY		_AC(0x00000100,UL)
+#define PMD_HUGE_ACCESSED	_AC(0x00000080,UL)
+#define PMD_HUGE_EXEC		_AC(0x00000040,UL)
+#define PMD_HUGE_SPLITTING	_AC(0x00000020,UL)
+#endif
+
 /* PGDs point to PMD tables which are 8K aligned.  */
 #define PGD_PADDR	_AC(0xfffffffc,UL)
 #define PGD_PADDR_SHIFT	_AC(11,UL)
@@ -219,6 +240,19 @@ static inline pte_t pfn_pte(unsigned long pfn, pgprot_t prot)
 }
 #define mk_pte(page, pgprot)	pfn_pte(page_to_pfn(page), (pgprot))
 
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+extern pmd_t pfn_pmd(unsigned long page_nr, pgprot_t pgprot);
+#define mk_pmd(page, pgprot)	pfn_pmd(page_to_pfn(page), (pgprot))
+
+extern pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot);
+
+static inline pmd_t pmd_mkhuge(pmd_t pmd)
+{
+	/* Do nothing, mk_pmd() does this part.  */
+	return pmd;
+}
+#endif
+
 /* This one can be done with two shifts.  */
 static inline unsigned long pte_pfn(pte_t pte)
 {
@@ -588,19 +622,130 @@ static inline unsigned long pte_special(pte_t pte)
 	return pte_val(pte) & _PAGE_SPECIAL;
 }
 
-#define pmd_set(pmdp, ptep)	\
-	(pmd_val(*(pmdp)) = (__pa((unsigned long) (ptep)) >> PMD_PADDR_SHIFT))
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+static inline int pmd_young(pmd_t pmd)
+{
+	return pmd_val(pmd) & PMD_HUGE_ACCESSED;
+}
+
+static inline int pmd_write(pmd_t pmd)
+{
+	return pmd_val(pmd) & PMD_HUGE_WRITE;
+}
+
+static inline unsigned long pmd_pfn(pmd_t pmd)
+{
+	unsigned long val = pmd_val(pmd) & PMD_HUGE_PADDR;
+
+	return val >> (PAGE_SHIFT - PMD_PADDR_SHIFT);
+}
+
+static inline int pmd_large(pmd_t pmd)
+{
+	return (pmd_val(pmd) & (PMD_ISHUGE | PMD_HUGE_PRESENT)) ==
+		(PMD_ISHUGE | PMD_HUGE_PRESENT);
+}
+
+static inline int pmd_trans_splitting(pmd_t pmd)
+{
+	return (pmd_val(pmd) & (PMD_ISHUGE|PMD_HUGE_SPLITTING)) ==
+		(PMD_ISHUGE|PMD_HUGE_SPLITTING);
+}
+
+static inline int pmd_trans_huge(pmd_t pmd)
+{
+	return pmd_val(pmd) & PMD_ISHUGE;
+}
+
+#define has_transparent_hugepage() 1
+
+static inline pmd_t pmd_mkold(pmd_t pmd)
+{
+	pmd_val(pmd) &= ~PMD_HUGE_ACCESSED;
+	return pmd;
+}
+
+static inline pmd_t pmd_wrprotect(pmd_t pmd)
+{
+	pmd_val(pmd) &= ~PMD_HUGE_WRITE;
+	return pmd;
+}
+
+static inline pmd_t pmd_mkdirty(pmd_t pmd)
+{
+	pmd_val(pmd) |= PMD_HUGE_DIRTY;
+	return pmd;
+}
+
+static inline pmd_t pmd_mkyoung(pmd_t pmd)
+{
+	pmd_val(pmd) |= PMD_HUGE_ACCESSED;
+	return pmd;
+}
+
+static inline pmd_t pmd_mkwrite(pmd_t pmd)
+{
+	pmd_val(pmd) |= PMD_HUGE_WRITE;
+	return pmd;
+}
+
+static inline pmd_t pmd_mknotpresent(pmd_t pmd)
+{
+	pmd_val(pmd) &= ~PMD_HUGE_PRESENT;
+	return pmd;
+}
+
+static inline pmd_t pmd_mksplitting(pmd_t pmd)
+{
+	pmd_val(pmd) |= PMD_HUGE_SPLITTING;
+	return pmd;
+}
+
+extern pgprot_t pmd_pgprot(pmd_t entry);
+#endif
+
+static inline int pmd_present(pmd_t pmd)
+{
+	return pmd_val(pmd) != 0U;
+}
+
+#define pmd_none(pmd)			(!pmd_val(pmd))
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+extern void set_pmd_at(struct mm_struct *mm, unsigned long addr,
+		       pmd_t *pmdp, pmd_t pmd);
+#else
+static inline void set_pmd_at(struct mm_struct *mm, unsigned long addr,
+			      pmd_t *pmdp, pmd_t pmd)
+{
+	*pmdp = pmd;
+}
+#endif
+
+static inline void pmd_set(struct mm_struct *mm, pmd_t *pmdp, pte_t *ptep)
+{
+	unsigned long val = __pa((unsigned long) (ptep)) >> PMD_PADDR_SHIFT;
+
+	pmd_val(*pmdp) = val;
+}
+
 #define pud_set(pudp, pmdp)	\
 	(pud_val(*(pudp)) = (__pa((unsigned long) (pmdp)) >> PGD_PADDR_SHIFT))
-#define __pmd_page(pmd)		\
-	((unsigned long) __va((((unsigned long)pmd_val(pmd))<<PMD_PADDR_SHIFT)))
+static inline unsigned long __pmd_page(pmd_t pmd)
+{
+	unsigned long paddr = (unsigned long) pmd_val(pmd);
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+	if (pmd_val(pmd) & PMD_ISHUGE)
+		paddr &= PMD_HUGE_PADDR;
+#endif
+	paddr <<= PMD_PADDR_SHIFT;
+	return ((unsigned long) __va(paddr));
+}
 #define pmd_page(pmd) 			virt_to_page((void *)__pmd_page(pmd))
 #define pud_page_vaddr(pud)		\
 	((unsigned long) __va((((unsigned long)pud_val(pud))<<PGD_PADDR_SHIFT)))
 #define pud_page(pud) 			virt_to_page((void *)pud_page_vaddr(pud))
-#define pmd_none(pmd)			(!pmd_val(pmd))
 #define pmd_bad(pmd)			(0)
-#define pmd_present(pmd)		(pmd_val(pmd) != 0U)
 #define pmd_clear(pmdp)			(pmd_val(*(pmdp)) = 0U)
 #define pud_none(pud)			(!pud_val(pud))
 #define pud_bad(pud)			(0)
@@ -634,6 +779,16 @@ static inline unsigned long pte_special(pte_t pte)
 extern void tlb_batch_add(struct mm_struct *mm, unsigned long vaddr,
 			  pte_t *ptep, pte_t orig, int fullmm);
 
+#define __HAVE_ARCH_PMDP_GET_AND_CLEAR
+static inline pmd_t pmdp_get_and_clear(struct mm_struct *mm,
+				       unsigned long addr,
+				       pmd_t *pmdp)
+{
+	pmd_t pmd = *pmdp;
+	set_pmd_at(mm, addr, pmdp, __pmd(0U));
+	return pmd;
+}
+
 static inline void __set_pte_at(struct mm_struct *mm, unsigned long addr,
 			     pte_t *ptep, pte_t pte, int fullmm)
 {
@@ -689,6 +844,16 @@ extern void mmu_info(struct seq_file *);
 
 struct vm_area_struct;
 extern void update_mmu_cache(struct vm_area_struct *, unsigned long, pte_t *);
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+extern void update_mmu_cache_pmd(struct vm_area_struct *vma, unsigned long addr,
+				 pmd_t *pmd);
+
+#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);
+#endif
 
 /* Encode and de-code a swap entry */
 #define __swp_type(entry)	(((entry).val >> PAGE_SHIFT) & 0xffUL)