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85 lines
2.3 KiB
85 lines
2.3 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* NOMMU mmap support for RomFS on MTD devices |
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* |
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* Copyright © 2007 Red Hat, Inc. All Rights Reserved. |
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* Written by David Howells ([email protected]) |
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*/ |
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#include <linux/mm.h> |
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#include <linux/mtd/super.h> |
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#include "internal.h" |
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/* |
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* try to determine where a shared mapping can be made |
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* - only supported for NOMMU at the moment (MMU can't doesn't copy private |
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* mappings) |
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* - attempts to map through to the underlying MTD device |
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*/ |
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static unsigned long romfs_get_unmapped_area(struct file *file, |
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unsigned long addr, |
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unsigned long len, |
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unsigned long pgoff, |
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unsigned long flags) |
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{ |
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struct inode *inode = file->f_mapping->host; |
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struct mtd_info *mtd = inode->i_sb->s_mtd; |
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unsigned long isize, offset, maxpages, lpages; |
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int ret; |
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if (!mtd) |
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return (unsigned long) -ENOSYS; |
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/* the mapping mustn't extend beyond the EOF */ |
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lpages = (len + PAGE_SIZE - 1) >> PAGE_SHIFT; |
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isize = i_size_read(inode); |
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offset = pgoff << PAGE_SHIFT; |
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maxpages = (isize + PAGE_SIZE - 1) >> PAGE_SHIFT; |
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if ((pgoff >= maxpages) || (maxpages - pgoff < lpages)) |
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return (unsigned long) -EINVAL; |
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if (addr != 0) |
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return (unsigned long) -EINVAL; |
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if (len > mtd->size || pgoff >= (mtd->size >> PAGE_SHIFT)) |
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return (unsigned long) -EINVAL; |
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offset += ROMFS_I(inode)->i_dataoffset; |
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if (offset >= mtd->size) |
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return (unsigned long) -EINVAL; |
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/* the mapping mustn't extend beyond the EOF */ |
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if ((offset + len) > mtd->size) |
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len = mtd->size - offset; |
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ret = mtd_get_unmapped_area(mtd, len, offset, flags); |
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if (ret == -EOPNOTSUPP) |
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ret = -ENOSYS; |
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return (unsigned long) ret; |
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} |
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/* |
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* permit a R/O mapping to be made directly through onto an MTD device if |
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* possible |
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*/ |
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static int romfs_mmap(struct file *file, struct vm_area_struct *vma) |
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{ |
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return vma->vm_flags & (VM_SHARED | VM_MAYSHARE) ? 0 : -ENOSYS; |
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} |
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static unsigned romfs_mmap_capabilities(struct file *file) |
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{ |
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struct mtd_info *mtd = file_inode(file)->i_sb->s_mtd; |
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if (!mtd) |
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return NOMMU_MAP_COPY; |
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return mtd_mmap_capabilities(mtd); |
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} |
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const struct file_operations romfs_ro_fops = { |
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.llseek = generic_file_llseek, |
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.read_iter = generic_file_read_iter, |
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.splice_read = generic_file_splice_read, |
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.mmap = romfs_mmap, |
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.get_unmapped_area = romfs_get_unmapped_area, |
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.mmap_capabilities = romfs_mmap_capabilities, |
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};
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