/* * IA-32 Huge TLB Page Support for Kernel. * * Copyright (C) 2002, Rohit Seth <rohit.seth@intel.com> */ #include <linux/init.h> #include <linux/fs.h> #include <linux/mm.h> #include <linux/hugetlb.h> #include <linux/pagemap.h> #include <linux/slab.h> #include <linux/err.h> #include <linux/sysctl.h> #include <asm/mman.h> #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; pud_t *pud; pte_t *pte = NULL; pgd = pgd_offset(mm, addr); pud = pud_alloc(mm, pgd, addr); 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; } pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr) { pgd_t *pgd; pud_t *pud; pmd_t *pmd = NULL; pgd = pgd_offset(mm, addr); if (pgd_present(*pgd)) { pud = pud_offset(pgd, addr); if (pud_present(*pud)) pmd = pmd_offset(pud, addr); } return (pte_t *) pmd; } #if 0 /* This is just for testing */ struct page * follow_huge_addr(struct mm_struct *mm, unsigned long address, int write) { unsigned long start = address; int length = 1; int nr; struct page *page; struct vm_area_struct *vma; vma = find_vma(mm, addr); if (!vma || !is_vm_hugetlb_page(vma)) return ERR_PTR(-EINVAL); pte = huge_pte_offset(mm, address); /* hugetlb should be locked, and hence, prefaulted */ WARN_ON(!pte || pte_none(*pte)); page = &pte_page(*pte)[vpfn % (HPAGE_SIZE/PAGE_SIZE)]; WARN_ON(!PageCompound(page)); return page; } int pmd_huge(pmd_t pmd) { return 0; } struct page * follow_huge_pmd(struct mm_struct *mm, unsigned long address, pmd_t *pmd, int write) { return NULL; } #else struct page * follow_huge_addr(struct mm_struct *mm, unsigned long address, int write) { return ERR_PTR(-EINVAL); } int pmd_huge(pmd_t pmd) { return !!(pmd_val(pmd) & _PAGE_PSE); } struct page * follow_huge_pmd(struct mm_struct *mm, unsigned long address, pmd_t *pmd, int write) { struct page *page; page = pte_page(*(pte_t *)pmd); if (page) page += ((address & ~HPAGE_MASK) >> PAGE_SHIFT); return page; } #endif /* x86_64 also uses this file */ #ifdef HAVE_ARCH_HUGETLB_UNMAPPED_AREA static unsigned long hugetlb_get_unmapped_area_bottomup(struct file *file, unsigned long addr, unsigned long len, unsigned long pgoff, unsigned long flags) { struct mm_struct *mm = current->mm; struct vm_area_struct *vma; unsigned long start_addr; if (len > mm->cached_hole_size) { start_addr = mm->free_area_cache; } else { start_addr = TASK_UNMAPPED_BASE; mm->cached_hole_size = 0; } full_search: addr = ALIGN(start_addr, HPAGE_SIZE); for (vma = find_vma(mm, addr); ; vma = vma->vm_next) { /* At this point: (!vma || addr < vma->vm_end). */ if (TASK_SIZE - len < addr) { /* * Start a new search - just in case we missed * some holes. */ if (start_addr != TASK_UNMAPPED_BASE) { start_addr = TASK_UNMAPPED_BASE; mm->cached_hole_size = 0; goto full_search; } return -ENOMEM; } if (!vma || addr + len <= vma->vm_start) { mm->free_area_cache = addr + len; return addr; } if (addr + mm->cached_hole_size < vma->vm_start) mm->cached_hole_size = vma->vm_start - addr; addr = ALIGN(vma->vm_end, HPAGE_SIZE); } } static unsigned long hugetlb_get_unmapped_area_topdown(struct file *file, unsigned long addr0, unsigned long len, unsigned long pgoff, unsigned long flags) { struct mm_struct *mm = current->mm; struct vm_area_struct *vma, *prev_vma; unsigned long base = mm->mmap_base, addr = addr0; unsigned long largest_hole = mm->cached_hole_size; int first_time = 1; /* don't allow allocations above current base */ if (mm->free_area_cache > base) mm->free_area_cache = base; if (len <= largest_hole) { largest_hole = 0; mm->free_area_cache = base; } try_again: /* make sure it can fit in the remaining address space */ if (mm->free_area_cache < len) goto fail; /* either no address requested or cant fit in requested address hole */ addr = (mm->free_area_cache - len) & HPAGE_MASK; do { /* * Lookup failure means no vma is above this address, * i.e. return with success: */ if (!(vma = find_vma_prev(mm, addr, &prev_vma))) return addr; /* * new region fits between prev_vma->vm_end and * vma->vm_start, use it: */ if (addr + len <= vma->vm_start && (!prev_vma || (addr >= prev_vma->vm_end))) { /* remember the address as a hint for next time */ mm->cached_hole_size = largest_hole; return (mm->free_area_cache = addr); } else { /* pull free_area_cache down to the first hole */ if (mm->free_area_cache == vma->vm_end) { mm->free_area_cache = vma->vm_start; mm->cached_hole_size = largest_hole; } } /* remember the largest hole we saw so far */ if (addr + largest_hole < vma->vm_start) largest_hole = vma->vm_start - addr; /* try just below the current vma->vm_start */ addr = (vma->vm_start - len) & HPAGE_MASK; } while (len <= vma->vm_start); fail: /* * if hint left us with no space for the requested * mapping then try again: */ if (first_time) { mm->free_area_cache = base; largest_hole = 0; first_time = 0; goto try_again; } /* * A failed mmap() very likely causes application failure, * so fall back to the bottom-up function here. This scenario * can happen with large stack limits and large mmap() * allocations. */ mm->free_area_cache = TASK_UNMAPPED_BASE; mm->cached_hole_size = ~0UL; addr = hugetlb_get_unmapped_area_bottomup(file, addr0, len, pgoff, flags); /* * Restore the topdown base: */ mm->free_area_cache = base; mm->cached_hole_size = ~0UL; return addr; } unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr, unsigned long len, unsigned long pgoff, unsigned long flags) { struct mm_struct *mm = current->mm; struct vm_area_struct *vma; if (len & ~HPAGE_MASK) return -EINVAL; if (len > TASK_SIZE) return -ENOMEM; if (flags & MAP_FIXED) { if (prepare_hugepage_range(addr, len)) return -EINVAL; return addr; } if (addr) { addr = ALIGN(addr, HPAGE_SIZE); vma = find_vma(mm, addr); if (TASK_SIZE - len >= addr && (!vma || addr + len <= vma->vm_start)) return addr; } if (mm->get_unmapped_area == arch_get_unmapped_area) return hugetlb_get_unmapped_area_bottomup(file, addr, len, pgoff, flags); else return hugetlb_get_unmapped_area_topdown(file, addr, len, pgoff, flags); } #endif /*HAVE_ARCH_HUGETLB_UNMAPPED_AREA*/