Merge branch 'drm-patches' of master.kernel.org:/pub/scm/linux/kernel/git/airlied...

[linux-drm-fsl-dcu.git] / arch / i386 / mm / hugetlbpage.c

diff --git a/arch/i386/mm/hugetlbpage.c b/arch/i386/mm/hugetlbpage.c
index 1719a8141f81aee9f480087be3e54a68eef4adef..6272a4fd9e7c82777380b68956c6824c02d254e2 100644 (file)
--- a/arch/i386/mm/hugetlbpage.c
+++ b/arch/i386/mm/hugetlbpage.c
@@ -17,6 +17,113 @@
 #include <asm/tlb.h>
 #include <asm/tlbflush.h>
 
+static unsigned long page_table_shareable(struct vm_area_struct *svma,
+                               struct vm_area_struct *vma,
+                               unsigned long addr, pgoff_t idx)
+{
+       unsigned long saddr = ((idx - svma->vm_pgoff) << PAGE_SHIFT) +
+                               svma->vm_start;
+       unsigned long sbase = saddr & PUD_MASK;
+       unsigned long s_end = sbase + PUD_SIZE;
+
+       /*
+        * match the virtual addresses, permission and the alignment of the
+        * page table page.
+        */
+       if (pmd_index(addr) != pmd_index(saddr) ||
+           vma->vm_flags != svma->vm_flags ||
+           sbase < svma->vm_start || svma->vm_end < s_end)
+               return 0;
+
+       return saddr;
+}
+
+static int vma_shareable(struct vm_area_struct *vma, unsigned long addr)
+{
+       unsigned long base = addr & PUD_MASK;
+       unsigned long end = base + PUD_SIZE;
+
+       /*
+        * check on proper vm_flags and page table alignment
+        */
+       if (vma->vm_flags & VM_MAYSHARE &&
+           vma->vm_start <= base && end <= vma->vm_end)
+               return 1;
+       return 0;
+}
+
+/*
+ * search for a shareable pmd page for hugetlb.
+ */
+static void huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud)
+{
+       struct vm_area_struct *vma = find_vma(mm, addr);
+       struct address_space *mapping = vma->vm_file->f_mapping;
+       pgoff_t idx = ((addr - vma->vm_start) >> PAGE_SHIFT) +
+                       vma->vm_pgoff;
+       struct prio_tree_iter iter;
+       struct vm_area_struct *svma;
+       unsigned long saddr;
+       pte_t *spte = NULL;
+
+       if (!vma_shareable(vma, addr))
+               return;
+
+       spin_lock(&mapping->i_mmap_lock);
+       vma_prio_tree_foreach(svma, &iter, &mapping->i_mmap, idx, idx) {
+               if (svma == vma)
+                       continue;
+
+               saddr = page_table_shareable(svma, vma, addr, idx);
+               if (saddr) {
+                       spte = huge_pte_offset(svma->vm_mm, saddr);
+                       if (spte) {
+                               get_page(virt_to_page(spte));
+                               break;
+                       }
+               }
+       }
+
+       if (!spte)
+               goto out;
+
+       spin_lock(&mm->page_table_lock);
+       if (pud_none(*pud))
+               pud_populate(mm, pud, (unsigned long) spte & PAGE_MASK);
+       else
+               put_page(virt_to_page(spte));
+       spin_unlock(&mm->page_table_lock);
+out:
+       spin_unlock(&mapping->i_mmap_lock);
+}
+
+/*
+ * unmap huge page backed by shared pte.
+ *
+ * Hugetlb pte page is ref counted at the time of mapping.  If pte is shared
+ * indicated by page_count > 1, unmap is achieved by clearing pud and
+ * decrementing the ref count. If count == 1, the pte page is not shared.
+ *
+ * called with vma->vm_mm->page_table_lock held.
+ *
+ * returns: 1 successfully unmapped a shared pte page
+ *         0 the underlying pte page is not shared, or it is the last user
+ */
+int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
+{
+       pgd_t *pgd = pgd_offset(mm, *addr);
+       pud_t *pud = pud_offset(pgd, *addr);
+
+       BUG_ON(page_count(virt_to_page(ptep)) == 0);
+       if (page_count(virt_to_page(ptep)) == 1)
+               return 0;
+
+       pud_clear(pud);
+       put_page(virt_to_page(ptep));
+       *addr = ALIGN(*addr, HPAGE_SIZE * PTRS_PER_PTE) - HPAGE_SIZE;
+       return 1;
+}
+
 pte_t *huge_pte_alloc(struct mm_struct *mm, unsigned long addr)
 {
        pgd_t *pgd;
@@ -25,8 +132,11 @@ pte_t *huge_pte_alloc(struct mm_struct *mm, unsigned long addr)
 
        pgd = pgd_offset(mm, addr);
        pud = pud_alloc(mm, pgd, addr);
-       if (pud)
+       if (pud) {
+               if (pud_none(*pud))
+                       huge_pmd_share(mm, addr, pud);
                pte = (pte_t *) pmd_alloc(mm, pud, addr);
+       }
        BUG_ON(pte && !pte_none(*pte) && !pte_huge(*pte));
 
        return pte;
@@ -257,6 +367,12 @@ hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
        if (len > TASK_SIZE)
                return -ENOMEM;
 
+       if (flags & MAP_FIXED) {
+               if (prepare_hugepage_range(addr, len, pgoff))
+                       return -EINVAL;
+               return addr;
+       }
+
        if (addr) {
                addr = ALIGN(addr, HPAGE_SIZE);
                vma = find_vma(mm, addr);