[PATCH 13 of 31] add pmd mangling functions to x86

[Andrea Arcangeli <aarcange@redhat.com>]

From: Andrea Arcangeli <aarcange@redhat.com>

Add needed pmd mangling functions with simmetry with their pte counterparts.
pmdp_freeze_flush is the only exception only present on the pmd side and it's
needed to serialize the VM against split_huge_page, it simply atomically clears
the present bit in the same way pmdp_clear_flush_young atomically clears the
accessed bit (and both need to flush the tlb to make it effective, which is
mandatory to happen synchronously for pmdp_freeze_flush).

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
---

diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -150,6 +150,67 @@ static inline pte_t pte_set_flags(pte_t 
 	return native_make_pte(v | set);
 }
 
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+static inline int pmd_young(pmd_t pmd)
+{
+	return pmd_flags(pmd) & _PAGE_ACCESSED;
+}
+
+static inline int pmd_write(pmd_t pmd)
+{
+	return pmd_flags(pmd) & _PAGE_RW;
+}
+
+static inline pmd_t pmd_set_flags(pmd_t pmd, pmdval_t set)
+{
+	pmdval_t v = native_pmd_val(pmd);
+
+	return native_make_pmd(v | set);
+}
+
+static inline pmd_t pmd_clear_flags(pmd_t pmd, pmdval_t clear)
+{
+	pmdval_t v = native_pmd_val(pmd);
+
+	return native_make_pmd(v & ~clear);
+}
+
+static inline pmd_t pmd_mkold(pmd_t pmd)
+{
+	return pmd_clear_flags(pmd, _PAGE_ACCESSED);
+}
+
+static inline pmd_t pmd_wrprotect(pmd_t pmd)
+{
+	return pmd_clear_flags(pmd, _PAGE_RW);
+}
+
+static inline pmd_t pmd_mkdirty(pmd_t pmd)
+{
+	return pmd_set_flags(pmd, _PAGE_DIRTY);
+}
+
+static inline pmd_t pmd_mkhuge(pmd_t pmd)
+{
+	return pmd_set_flags(pmd, _PAGE_PSE);
+}
+
+static inline pmd_t pmd_mkyoung(pmd_t pmd)
+{
+	return pmd_set_flags(pmd, _PAGE_ACCESSED);
+}
+
+static inline pmd_t pmd_mkwrite(pmd_t pmd)
+{
+	return pmd_set_flags(pmd, _PAGE_RW);
+}
+
+static inline int pmd_same(pmd_t a, pmd_t b)
+{
+	return a.pmd == b.pmd;
+}
+#endif
+
 static inline pte_t pte_clear_flags(pte_t pte, pteval_t clear)
 {
 	pteval_t v = native_pte_val(pte);
@@ -351,7 +412,7 @@ static inline unsigned long pmd_page_vad
  * Currently stuck as a macro due to indirect forward reference to
  * linux/mmzone.h's __section_mem_map_addr() definition:
  */
-#define pmd_page(pmd)	pfn_to_page(pmd_val(pmd) >> PAGE_SHIFT)
+#define pmd_page(pmd)	pfn_to_page((pmd_val(pmd) & PTE_PFN_MASK) >> PAGE_SHIFT)
 
 /*
  * the pmd page can be thought of an array like this: pmd_t[PTRS_PER_PMD]
@@ -372,6 +433,7 @@ static inline unsigned long pmd_index(un
  * to linux/mm.h:page_to_nid())
  */
 #define mk_pte(page, pgprot)   pfn_pte(page_to_pfn(page), (pgprot))
+#define mk_pmd(page, pgprot)   pfn_pmd(page_to_pfn(page), (pgprot))
 
 /*
  * the pte page can be thought of an array like this: pte_t[PTRS_PER_PTE]
@@ -568,14 +630,21 @@ struct vm_area_struct;
 extern int ptep_set_access_flags(struct vm_area_struct *vma,
 				 unsigned long address, pte_t *ptep,
 				 pte_t entry, int dirty);
+extern int pmdp_set_access_flags(struct vm_area_struct *vma,
+				 unsigned long address, pmd_t *pmdp,
+				 pmd_t entry, int dirty);
 
 #define __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG
 extern int ptep_test_and_clear_young(struct vm_area_struct *vma,
 				     unsigned long addr, pte_t *ptep);
+extern int pmdp_test_and_clear_young(struct vm_area_struct *vma,
+				     unsigned long addr, pmd_t *pmdp);
 
 #define __HAVE_ARCH_PTEP_CLEAR_YOUNG_FLUSH
 extern int ptep_clear_flush_young(struct vm_area_struct *vma,
 				  unsigned long address, pte_t *ptep);
+extern int pmdp_clear_flush_young(struct vm_area_struct *vma,
+				  unsigned long address, pmd_t *pmdp);
 
 #define __HAVE_ARCH_PTEP_GET_AND_CLEAR
 static inline pte_t ptep_get_and_clear(struct mm_struct *mm, unsigned long addr,
@@ -586,6 +655,16 @@ static inline pte_t ptep_get_and_clear(s
 	return pte;
 }
 
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+static inline pmd_t pmdp_get_and_clear(struct mm_struct *mm, unsigned long addr,
+				       pmd_t *pmdp)
+{
+	pmd_t pmd = native_pmdp_get_and_clear(pmdp);
+	pmd_update(mm, addr, pmdp);
+	return pmd;
+}
+#endif
+
 #define __HAVE_ARCH_PTEP_GET_AND_CLEAR_FULL
 static inline pte_t ptep_get_and_clear_full(struct mm_struct *mm,
 					    unsigned long addr, pte_t *ptep,
@@ -612,6 +691,18 @@ static inline void ptep_set_wrprotect(st
 	pte_update(mm, addr, ptep);
 }
 
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+static inline void pmdp_set_wrprotect(struct mm_struct *mm,
+				      unsigned long addr, pmd_t *pmdp)
+{
+	clear_bit(_PAGE_BIT_RW, (unsigned long *)&pmdp->pmd);
+	pmd_update(mm, addr, pmdp);
+}
+#endif
+
+extern void pmdp_splitting_flush(struct vm_area_struct *vma,
+				 unsigned long addr, pmd_t *pmdp);
+
 /*
  * clone_pgd_range(pgd_t *dst, pgd_t *src, int count);
  *
diff --git a/arch/x86/include/asm/pgtable_64.h b/arch/x86/include/asm/pgtable_64.h
--- a/arch/x86/include/asm/pgtable_64.h
+++ b/arch/x86/include/asm/pgtable_64.h
@@ -71,6 +71,18 @@ static inline pte_t native_ptep_get_and_
 	return ret;
 #endif
 }
+static inline pmd_t native_pmdp_get_and_clear(pmd_t *xp)
+{
+#ifdef CONFIG_SMP
+	return native_make_pmd(xchg(&xp->pmd, 0));
+#else
+	/* native_local_pmdp_get_and_clear,
+	   but duplicated because of cyclic dependency */
+	pmd_t ret = *xp;
+	native_pmd_clear(NULL, 0, xp);
+	return ret;
+#endif
+}
 
 static inline void native_set_pmd(pmd_t *pmdp, pmd_t pmd)
 {
diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c
@@ -288,6 +288,25 @@ int ptep_set_access_flags(struct vm_area
 	return changed;
 }
 
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+int pmdp_set_access_flags(struct vm_area_struct *vma,
+			  unsigned long address, pmd_t *pmdp,
+			  pmd_t entry, int dirty)
+{
+	int changed = !pmd_same(*pmdp, entry);
+
+	VM_BUG_ON(address & ~HPAGE_PMD_MASK);
+
+	if (changed && dirty) {
+		*pmdp = entry;
+		pmd_update_defer(vma->vm_mm, address, pmdp);
+		flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
+	}
+
+	return changed;
+}
+#endif
+
 int ptep_test_and_clear_young(struct vm_area_struct *vma,
 			      unsigned long addr, pte_t *ptep)
 {
@@ -303,6 +322,23 @@ int ptep_test_and_clear_young(struct vm_
 	return ret;
 }
 
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+int pmdp_test_and_clear_young(struct vm_area_struct *vma,
+			      unsigned long addr, pmd_t *pmdp)
+{
+	int ret = 0;
+
+	if (pmd_young(*pmdp))
+		ret = test_and_clear_bit(_PAGE_BIT_ACCESSED,
+					 (unsigned long *) &pmdp->pmd);
+
+	if (ret)
+		pmd_update(vma->vm_mm, addr, pmdp);
+
+	return ret;
+}
+#endif
+
 int ptep_clear_flush_young(struct vm_area_struct *vma,
 			   unsigned long address, pte_t *ptep)
 {
@@ -315,6 +351,36 @@ int ptep_clear_flush_young(struct vm_are
 	return young;
 }
 
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+int pmdp_clear_flush_young(struct vm_area_struct *vma,
+			   unsigned long address, pmd_t *pmdp)
+{
+	int young;
+
+	VM_BUG_ON(address & ~HPAGE_PMD_MASK);
+
+	young = pmdp_test_and_clear_young(vma, address, pmdp);
+	if (young)
+		flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
+
+	return young;
+}
+
+void pmdp_splitting_flush(struct vm_area_struct *vma,
+			  unsigned long address, pmd_t *pmdp)
+{
+	int set;
+	VM_BUG_ON(address & ~HPAGE_PMD_MASK);
+	set = !test_and_set_bit(_PAGE_BIT_SPLITTING,
+				(unsigned long *)&pmdp->pmd);
+	if (set) {
+		pmd_update(vma->vm_mm, address, pmdp);
+		/* need tlb flush only to serialize against gup-fast */
+		flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
+	}
+}
+#endif
+
 /**
  * reserve_top_address - reserves a hole in the top of kernel address space
  * @reserve - size of hole to reserve

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