+++ /dev/null
-/*
- * linux/mm/fremap.c
- *
- * Explicit pagetable population and nonlinear (random) mappings support.
- *
- * started by Ingo Molnar, Copyright (C) 2002, 2003
- */
-#include <linux/export.h>
-#include <linux/backing-dev.h>
-#include <linux/mm.h>
-#include <linux/swap.h>
-#include <linux/file.h>
-#include <linux/mman.h>
-#include <linux/pagemap.h>
-#include <linux/swapops.h>
-#include <linux/rmap.h>
-#include <linux/syscalls.h>
-#include <linux/mmu_notifier.h>
-
-#include <asm/mmu_context.h>
-#include <asm/cacheflush.h>
-#include <asm/tlbflush.h>
-
-#include "internal.h"
-
-static int mm_counter(struct page *page)
-{
- return PageAnon(page) ? MM_ANONPAGES : MM_FILEPAGES;
-}
-
-static void zap_pte(struct mm_struct *mm, struct vm_area_struct *vma,
- unsigned long addr, pte_t *ptep)
-{
- pte_t pte = *ptep;
- struct page *page;
- swp_entry_t entry;
-
- if (pte_present(pte)) {
- flush_cache_page(vma, addr, pte_pfn(pte));
- pte = ptep_clear_flush_notify(vma, addr, ptep);
- page = vm_normal_page(vma, addr, pte);
- if (page) {
- if (pte_dirty(pte))
- set_page_dirty(page);
- update_hiwater_rss(mm);
- dec_mm_counter(mm, mm_counter(page));
- page_remove_rmap(page);
- page_cache_release(page);
- }
- } else { /* zap_pte() is not called when pte_none() */
- if (!pte_file(pte)) {
- update_hiwater_rss(mm);
- entry = pte_to_swp_entry(pte);
- if (non_swap_entry(entry)) {
- if (is_migration_entry(entry)) {
- page = migration_entry_to_page(entry);
- dec_mm_counter(mm, mm_counter(page));
- }
- } else {
- free_swap_and_cache(entry);
- dec_mm_counter(mm, MM_SWAPENTS);
- }
- }
- pte_clear_not_present_full(mm, addr, ptep, 0);
- }
-}
-
-/*
- * Install a file pte to a given virtual memory address, release any
- * previously existing mapping.
- */
-static int install_file_pte(struct mm_struct *mm, struct vm_area_struct *vma,
- unsigned long addr, unsigned long pgoff, pgprot_t prot)
-{
- int err = -ENOMEM;
- pte_t *pte, ptfile;
- spinlock_t *ptl;
-
- pte = get_locked_pte(mm, addr, &ptl);
- if (!pte)
- goto out;
-
- ptfile = pgoff_to_pte(pgoff);
-
- if (!pte_none(*pte))
- zap_pte(mm, vma, addr, pte);
-
- set_pte_at(mm, addr, pte, pte_file_mksoft_dirty(ptfile));
- /*
- * We don't need to run update_mmu_cache() here because the "file pte"
- * being installed by install_file_pte() is not a real pte - it's a
- * non-present entry (like a swap entry), noting what file offset should
- * be mapped there when there's a fault (in a non-linear vma where
- * that's not obvious).
- */
- pte_unmap_unlock(pte, ptl);
- err = 0;
-out:
- return err;
-}
-
-int generic_file_remap_pages(struct vm_area_struct *vma, unsigned long addr,
- unsigned long size, pgoff_t pgoff)
-{
- struct mm_struct *mm = vma->vm_mm;
- int err;
-
- do {
- err = install_file_pte(mm, vma, addr, pgoff, vma->vm_page_prot);
- if (err)
- return err;
-
- size -= PAGE_SIZE;
- addr += PAGE_SIZE;
- pgoff++;
- } while (size);
-
- return 0;
-}
-EXPORT_SYMBOL(generic_file_remap_pages);
-
-/**
- * sys_remap_file_pages - remap arbitrary pages of an existing VM_SHARED vma
- * @start: start of the remapped virtual memory range
- * @size: size of the remapped virtual memory range
- * @prot: new protection bits of the range (see NOTE)
- * @pgoff: to-be-mapped page of the backing store file
- * @flags: 0 or MAP_NONBLOCKED - the later will cause no IO.
- *
- * sys_remap_file_pages remaps arbitrary pages of an existing VM_SHARED vma
- * (shared backing store file).
- *
- * This syscall works purely via pagetables, so it's the most efficient
- * way to map the same (large) file into a given virtual window. Unlike
- * mmap()/mremap() it does not create any new vmas. The new mappings are
- * also safe across swapout.
- *
- * NOTE: the @prot parameter right now is ignored (but must be zero),
- * and the vma's default protection is used. Arbitrary protections
- * might be implemented in the future.
- */
-SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,
- unsigned long, prot, unsigned long, pgoff, unsigned long, flags)
-{
- struct mm_struct *mm = current->mm;
- struct address_space *mapping;
- struct vm_area_struct *vma;
- int err = -EINVAL;
- int has_write_lock = 0;
- vm_flags_t vm_flags = 0;
-
- pr_warn_once("%s (%d) uses deprecated remap_file_pages() syscall. "
- "See Documentation/vm/remap_file_pages.txt.\n",
- current->comm, current->pid);
-
- if (prot)
- return err;
- /*
- * Sanitize the syscall parameters:
- */
- start = start & PAGE_MASK;
- size = size & PAGE_MASK;
-
- /* Does the address range wrap, or is the span zero-sized? */
- if (start + size <= start)
- return err;
-
- /* Does pgoff wrap? */
- if (pgoff + (size >> PAGE_SHIFT) < pgoff)
- return err;
-
- /* Can we represent this offset inside this architecture's pte's? */
-#if PTE_FILE_MAX_BITS < BITS_PER_LONG
- if (pgoff + (size >> PAGE_SHIFT) >= (1UL << PTE_FILE_MAX_BITS))
- return err;
-#endif
-
- /* We need down_write() to change vma->vm_flags. */
- down_read(&mm->mmap_sem);
- retry:
- vma = find_vma(mm, start);
-
- /*
- * Make sure the vma is shared, that it supports prefaulting,
- * and that the remapped range is valid and fully within
- * the single existing vma.
- */
- if (!vma || !(vma->vm_flags & VM_SHARED))
- goto out;
-
- if (!vma->vm_ops || !vma->vm_ops->remap_pages)
- goto out;
-
- if (start < vma->vm_start || start + size > vma->vm_end)
- goto out;
-
- /* Must set VM_NONLINEAR before any pages are populated. */
- if (!(vma->vm_flags & VM_NONLINEAR)) {
- /*
- * vm_private_data is used as a swapout cursor
- * in a VM_NONLINEAR vma.
- */
- if (vma->vm_private_data)
- goto out;
-
- /* Don't need a nonlinear mapping, exit success */
- if (pgoff == linear_page_index(vma, start)) {
- err = 0;
- goto out;
- }
-
- if (!has_write_lock) {
-get_write_lock:
- up_read(&mm->mmap_sem);
- down_write(&mm->mmap_sem);
- has_write_lock = 1;
- goto retry;
- }
- mapping = vma->vm_file->f_mapping;
- /*
- * page_mkclean doesn't work on nonlinear vmas, so if
- * dirty pages need to be accounted, emulate with linear
- * vmas.
- */
- if (mapping_cap_account_dirty(mapping)) {
- unsigned long addr;
- struct file *file = get_file(vma->vm_file);
- /* mmap_region may free vma; grab the info now */
- vm_flags = vma->vm_flags;
-
- addr = mmap_region(file, start, size, vm_flags, pgoff);
- fput(file);
- if (IS_ERR_VALUE(addr)) {
- err = addr;
- } else {
- BUG_ON(addr != start);
- err = 0;
- }
- goto out_freed;
- }
- i_mmap_lock_write(mapping);
- flush_dcache_mmap_lock(mapping);
- vma->vm_flags |= VM_NONLINEAR;
- vma_interval_tree_remove(vma, &mapping->i_mmap);
- vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear);
- flush_dcache_mmap_unlock(mapping);
- i_mmap_unlock_write(mapping);
- }
-
- if (vma->vm_flags & VM_LOCKED) {
- /*
- * drop PG_Mlocked flag for over-mapped range
- */
- if (!has_write_lock)
- goto get_write_lock;
- vm_flags = vma->vm_flags;
- munlock_vma_pages_range(vma, start, start + size);
- vma->vm_flags = vm_flags;
- }
-
- mmu_notifier_invalidate_range_start(mm, start, start + size);
- err = vma->vm_ops->remap_pages(vma, start, size, pgoff);
- mmu_notifier_invalidate_range_end(mm, start, start + size);
-
- /*
- * We can't clear VM_NONLINEAR because we'd have to do
- * it after ->populate completes, and that would prevent
- * downgrading the lock. (Locks can't be upgraded).
- */
-
-out:
- if (vma)
- vm_flags = vma->vm_flags;
-out_freed:
- if (likely(!has_write_lock))
- up_read(&mm->mmap_sem);
- else
- up_write(&mm->mmap_sem);
- if (!err && ((vm_flags & VM_LOCKED) || !(flags & MAP_NONBLOCK)))
- mm_populate(start, size);
-
- return err;
-}
projects / linux-2.6-block.git / blobdiff