diff options
Diffstat (limited to 'mm/filemap_xip.c')
| -rw-r--r-- | mm/filemap_xip.c | 447 |
1 files changed, 447 insertions, 0 deletions
diff --git a/mm/filemap_xip.c b/mm/filemap_xip.c new file mode 100644 index 00000000000..3b6e384b98a --- /dev/null +++ b/mm/filemap_xip.c @@ -0,0 +1,447 @@ +/* + * linux/mm/filemap_xip.c + * + * Copyright (C) 2005 IBM Corporation + * Author: Carsten Otte <cotte@de.ibm.com> + * + * derived from linux/mm/filemap.c - Copyright (C) Linus Torvalds + * + */ + +#include <linux/fs.h> +#include <linux/pagemap.h> +#include <linux/module.h> +#include <linux/uio.h> +#include <linux/rmap.h> +#include <asm/tlbflush.h> +#include "filemap.h" + +/* + * This is a file read routine for execute in place files, and uses + * the mapping->a_ops->get_xip_page() function for the actual low-level + * stuff. + * + * Note the struct file* is not used at all. It may be NULL. + */ +static void +do_xip_mapping_read(struct address_space *mapping, + struct file_ra_state *_ra, + struct file *filp, + loff_t *ppos, + read_descriptor_t *desc, + read_actor_t actor) +{ + struct inode *inode = mapping->host; + unsigned long index, end_index, offset; + loff_t isize; + + BUG_ON(!mapping->a_ops->get_xip_page); + + index = *ppos >> PAGE_CACHE_SHIFT; + offset = *ppos & ~PAGE_CACHE_MASK; + + isize = i_size_read(inode); + if (!isize) + goto out; + + end_index = (isize - 1) >> PAGE_CACHE_SHIFT; + for (;;) { + struct page *page; + unsigned long nr, ret; + + /* nr is the maximum number of bytes to copy from this page */ + nr = PAGE_CACHE_SIZE; + if (index >= end_index) { + if (index > end_index) + goto out; + nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1; + if (nr <= offset) { + goto out; + } + } + nr = nr - offset; + + page = mapping->a_ops->get_xip_page(mapping, + index*(PAGE_SIZE/512), 0); + if (!page) + goto no_xip_page; + if (unlikely(IS_ERR(page))) { + if (PTR_ERR(page) == -ENODATA) { + /* sparse */ + page = virt_to_page(empty_zero_page); + } else { + desc->error = PTR_ERR(page); + goto out; + } + } else + BUG_ON(!PageUptodate(page)); + + /* If users can be writing to this page using arbitrary + * virtual addresses, take care about potential aliasing + * before reading the page on the kernel side. + */ + if (mapping_writably_mapped(mapping)) + flush_dcache_page(page); + + /* + * Ok, we have the page, and it's up-to-date, so + * now we can copy it to user space... + * + * The actor routine returns how many bytes were actually used.. + * NOTE! This may not be the same as how much of a user buffer + * we filled up (we may be padding etc), so we can only update + * "pos" here (the actor routine has to update the user buffer + * pointers and the remaining count). + */ + ret = actor(desc, page, offset, nr); + offset += ret; + index += offset >> PAGE_CACHE_SHIFT; + offset &= ~PAGE_CACHE_MASK; + + if (ret == nr && desc->count) + continue; + goto out; + +no_xip_page: + /* Did not get the page. Report it */ + desc->error = -EIO; + goto out; + } + +out: + *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset; + if (filp) + file_accessed(filp); +} + +ssize_t +xip_file_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos) +{ + read_descriptor_t desc; + + if (!access_ok(VERIFY_WRITE, buf, len)) + return -EFAULT; + + desc.written = 0; + desc.arg.buf = buf; + desc.count = len; + desc.error = 0; + + do_xip_mapping_read(filp->f_mapping, &filp->f_ra, filp, + ppos, &desc, file_read_actor); + + if (desc.written) + return desc.written; + else + return desc.error; +} +EXPORT_SYMBOL_GPL(xip_file_read); + +ssize_t +xip_file_sendfile(struct file *in_file, loff_t *ppos, + size_t count, read_actor_t actor, void *target) +{ + read_descriptor_t desc; + + if (!count) + return 0; + + desc.written = 0; + desc.count = count; + desc.arg.data = target; + desc.error = 0; + + do_xip_mapping_read(in_file->f_mapping, &in_file->f_ra, in_file, + ppos, &desc, actor); + if (desc.written) + return desc.written; + return desc.error; +} +EXPORT_SYMBOL_GPL(xip_file_sendfile); + +/* + * __xip_unmap is invoked from xip_unmap and + * xip_write + * + * This function walks all vmas of the address_space and unmaps the + * empty_zero_page when found at pgoff. Should it go in rmap.c? + */ +static void +__xip_unmap (struct address_space * mapping, + unsigned long pgoff) +{ + struct vm_area_struct *vma; + struct mm_struct *mm; + struct prio_tree_iter iter; + unsigned long address; + pte_t *pte; + pte_t pteval; + + spin_lock(&mapping->i_mmap_lock); + vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) { + mm = vma->vm_mm; + address = vma->vm_start + + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT); + BUG_ON(address < vma->vm_start || address >= vma->vm_end); + /* + * We need the page_table_lock to protect us from page faults, + * munmap, fork, etc... + */ + pte = page_check_address(virt_to_page(empty_zero_page), mm, + address); + if (!IS_ERR(pte)) { + /* Nuke the page table entry. */ + flush_cache_page(vma, address, pte_pfn(pte)); + pteval = ptep_clear_flush(vma, address, pte); + BUG_ON(pte_dirty(pteval)); + pte_unmap(pte); + spin_unlock(&mm->page_table_lock); + } + } + spin_unlock(&mapping->i_mmap_lock); +} + +/* + * xip_nopage() is invoked via the vma operations vector for a + * mapped memory region to read in file data during a page fault. + * + * This function is derived from filemap_nopage, but used for execute in place + */ +static struct page * +xip_file_nopage(struct vm_area_struct * area, + unsigned long address, + int *type) +{ + struct file *file = area->vm_file; + struct address_space *mapping = file->f_mapping; + struct inode *inode = mapping->host; + struct page *page; + unsigned long size, pgoff, endoff; + + pgoff = ((address - area->vm_start) >> PAGE_CACHE_SHIFT) + + area->vm_pgoff; + endoff = ((area->vm_end - area->vm_start) >> PAGE_CACHE_SHIFT) + + area->vm_pgoff; + + size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; + if (pgoff >= size) { + return NULL; + } + + page = mapping->a_ops->get_xip_page(mapping, pgoff*(PAGE_SIZE/512), 0); + if (!IS_ERR(page)) { + BUG_ON(!PageUptodate(page)); + return page; + } + if (PTR_ERR(page) != -ENODATA) + return NULL; + + /* sparse block */ + if ((area->vm_flags & (VM_WRITE | VM_MAYWRITE)) && + (area->vm_flags & (VM_SHARED| VM_MAYSHARE)) && + (!(mapping->host->i_sb->s_flags & MS_RDONLY))) { + /* maybe shared writable, allocate new block */ + page = mapping->a_ops->get_xip_page (mapping, + pgoff*(PAGE_SIZE/512), 1); + if (IS_ERR(page)) + return NULL; + BUG_ON(!PageUptodate(page)); + /* unmap page at pgoff from all other vmas */ + __xip_unmap(mapping, pgoff); + } else { + /* not shared and writable, use empty_zero_page */ + page = virt_to_page(empty_zero_page); + } + + return page; +} + +static struct vm_operations_struct xip_file_vm_ops = { + .nopage = xip_file_nopage, +}; + +int xip_file_mmap(struct file * file, struct vm_area_struct * vma) +{ + BUG_ON(!file->f_mapping->a_ops->get_xip_page); + + file_accessed(file); + vma->vm_ops = &xip_file_vm_ops; + return 0; +} +EXPORT_SYMBOL_GPL(xip_file_mmap); + +static ssize_t +__xip_file_write(struct file *filp, const char __user *buf, + size_t count, loff_t pos, loff_t *ppos) +{ + struct address_space * mapping = filp->f_mapping; + struct address_space_operations *a_ops = mapping->a_ops; + struct inode *inode = mapping->host; + long status = 0; + struct page *page; + size_t bytes; + ssize_t written = 0; + + BUG_ON(!mapping->a_ops->get_xip_page); + + do { + unsigned long index; + unsigned long offset; + size_t copied; + + offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */ + index = pos >> PAGE_CACHE_SHIFT; + bytes = PAGE_CACHE_SIZE - offset; + if (bytes > count) + bytes = count; + + /* + * Bring in the user page that we will copy from _first_. + * Otherwise there's a nasty deadlock on copying from the + * same page as we're writing to, without it being marked + * up-to-date. + */ + fault_in_pages_readable(buf, bytes); + + page = a_ops->get_xip_page(mapping, + index*(PAGE_SIZE/512), 0); + if (IS_ERR(page) && (PTR_ERR(page) == -ENODATA)) { + /* we allocate a new page unmap it */ + page = a_ops->get_xip_page(mapping, + index*(PAGE_SIZE/512), 1); + if (!IS_ERR(page)) + /* unmap page at pgoff from all other vmas */ + __xip_unmap(mapping, index); + } + + if (IS_ERR(page)) { + status = PTR_ERR(page); + break; + } + + BUG_ON(!PageUptodate(page)); + + copied = filemap_copy_from_user(page, offset, buf, bytes); + flush_dcache_page(page); + if (likely(copied > 0)) { + status = copied; + + if (status >= 0) { + written += status; + count -= status; + pos += status; + buf += status; + } + } + if (unlikely(copied != bytes)) + if (status >= 0) + status = -EFAULT; + if (status < 0) + break; + } while (count); + *ppos = pos; + /* + * No need to use i_size_read() here, the i_size + * cannot change under us because we hold i_sem. + */ + if (pos > inode->i_size) { + i_size_write(inode, pos); + mark_inode_dirty(inode); + } + + return written ? written : status; +} + +ssize_t +xip_file_write(struct file *filp, const char __user *buf, size_t len, + loff_t *ppos) +{ + struct address_space *mapping = filp->f_mapping; + struct inode *inode = mapping->host; + size_t count; + loff_t pos; + ssize_t ret; + + down(&inode->i_sem); + + if (!access_ok(VERIFY_READ, buf, len)) { + ret=-EFAULT; + goto out_up; + } + + pos = *ppos; + count = len; + + vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE); + + /* We can write back this queue in page reclaim */ + current->backing_dev_info = mapping->backing_dev_info; + + ret = generic_write_checks(filp, &pos, &count, S_ISBLK(inode->i_mode)); + if (ret) + goto out_backing; + if (count == 0) + goto out_backing; + + ret = remove_suid(filp->f_dentry); + if (ret) + goto out_backing; + + inode_update_time(inode, 1); + + ret = __xip_file_write (filp, buf, count, pos, ppos); + + out_backing: + current->backing_dev_info = NULL; + out_up: + up(&inode->i_sem); + return ret; +} +EXPORT_SYMBOL_GPL(xip_file_write); + +/* + * truncate a page used for execute in place + * functionality is analog to block_truncate_page but does use get_xip_page + * to get the page instead of page cache + */ +int +xip_truncate_page(struct address_space *mapping, loff_t from) +{ + pgoff_t index = from >> PAGE_CACHE_SHIFT; + unsigned offset = from & (PAGE_CACHE_SIZE-1); + unsigned blocksize; + unsigned length; + struct page *page; + void *kaddr; + + BUG_ON(!mapping->a_ops->get_xip_page); + + blocksize = 1 << mapping->host->i_blkbits; + length = offset & (blocksize - 1); + + /* Block boundary? Nothing to do */ + if (!length) + return 0; + + length = blocksize - length; + + page = mapping->a_ops->get_xip_page(mapping, + index*(PAGE_SIZE/512), 0); + if (!page) + return -ENOMEM; + if (unlikely(IS_ERR(page))) { + if (PTR_ERR(page) == -ENODATA) + /* Hole? No need to truncate */ + return 0; + else + return PTR_ERR(page); + } else + BUG_ON(!PageUptodate(page)); + kaddr = kmap_atomic(page, KM_USER0); + memset(kaddr + offset, 0, length); + kunmap_atomic(kaddr, KM_USER0); + + flush_dcache_page(page); + return 0; +} +EXPORT_SYMBOL_GPL(xip_truncate_page); |