1 // SPDX-License-Identifier: GPL-2.0-or-later <<
2 /* NOMMU mmap support for RomFS on MTD devices 1 /* NOMMU mmap support for RomFS on MTD devices
3 * 2 *
4 * Copyright © 2007 Red Hat, Inc. All Rights 3 * Copyright © 2007 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.c 4 * Written by David Howells (dhowells@redhat.com)
>> 5 *
>> 6 * This program is free software; you can redistribute it and/or
>> 7 * modify it under the terms of the GNU General Public License
>> 8 * as published by the Free Software Foundation; either version
>> 9 * 2 of the License, or (at your option) any later version.
6 */ 10 */
7 11
8 #include <linux/mm.h> 12 #include <linux/mm.h>
9 #include <linux/mtd/super.h> 13 #include <linux/mtd/super.h>
10 #include "internal.h" 14 #include "internal.h"
11 15
12 /* 16 /*
13 * try to determine where a shared mapping can 17 * try to determine where a shared mapping can be made
14 * - only supported for NOMMU at the moment (M 18 * - only supported for NOMMU at the moment (MMU can't doesn't copy private
15 * mappings) 19 * mappings)
16 * - attempts to map through to the underlying 20 * - attempts to map through to the underlying MTD device
17 */ 21 */
18 static unsigned long romfs_get_unmapped_area(s 22 static unsigned long romfs_get_unmapped_area(struct file *file,
19 u 23 unsigned long addr,
20 u 24 unsigned long len,
21 u 25 unsigned long pgoff,
22 u 26 unsigned long flags)
23 { 27 {
24 struct inode *inode = file->f_mapping- 28 struct inode *inode = file->f_mapping->host;
25 struct mtd_info *mtd = inode->i_sb->s_ 29 struct mtd_info *mtd = inode->i_sb->s_mtd;
26 unsigned long isize, offset, maxpages, 30 unsigned long isize, offset, maxpages, lpages;
27 int ret; 31 int ret;
28 32
29 if (!mtd) 33 if (!mtd)
30 return (unsigned long) -ENOSYS 34 return (unsigned long) -ENOSYS;
31 35
32 /* the mapping mustn't extend beyond t 36 /* the mapping mustn't extend beyond the EOF */
33 lpages = (len + PAGE_SIZE - 1) >> PAGE 37 lpages = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
34 isize = i_size_read(inode); 38 isize = i_size_read(inode);
35 offset = pgoff << PAGE_SHIFT; 39 offset = pgoff << PAGE_SHIFT;
36 40
37 maxpages = (isize + PAGE_SIZE - 1) >> 41 maxpages = (isize + PAGE_SIZE - 1) >> PAGE_SHIFT;
38 if ((pgoff >= maxpages) || (maxpages - 42 if ((pgoff >= maxpages) || (maxpages - pgoff < lpages))
39 return (unsigned long) -EINVAL 43 return (unsigned long) -EINVAL;
40 44
41 if (addr != 0) 45 if (addr != 0)
42 return (unsigned long) -EINVAL 46 return (unsigned long) -EINVAL;
43 47
44 if (len > mtd->size || pgoff >= (mtd-> 48 if (len > mtd->size || pgoff >= (mtd->size >> PAGE_SHIFT))
45 return (unsigned long) -EINVAL 49 return (unsigned long) -EINVAL;
46 50
47 offset += ROMFS_I(inode)->i_dataoffset 51 offset += ROMFS_I(inode)->i_dataoffset;
48 if (offset >= mtd->size) 52 if (offset >= mtd->size)
49 return (unsigned long) -EINVAL 53 return (unsigned long) -EINVAL;
50 /* the mapping mustn't extend beyond t 54 /* the mapping mustn't extend beyond the EOF */
51 if ((offset + len) > mtd->size) 55 if ((offset + len) > mtd->size)
52 len = mtd->size - offset; 56 len = mtd->size - offset;
53 57
54 ret = mtd_get_unmapped_area(mtd, len, 58 ret = mtd_get_unmapped_area(mtd, len, offset, flags);
55 if (ret == -EOPNOTSUPP) 59 if (ret == -EOPNOTSUPP)
56 ret = -ENOSYS; 60 ret = -ENOSYS;
57 return (unsigned long) ret; 61 return (unsigned long) ret;
58 } 62 }
59 63
60 /* 64 /*
61 * permit a R/O mapping to be made directly th 65 * permit a R/O mapping to be made directly through onto an MTD device if
62 * possible 66 * possible
63 */ 67 */
64 static int romfs_mmap(struct file *file, struc 68 static int romfs_mmap(struct file *file, struct vm_area_struct *vma)
65 { 69 {
66 return is_nommu_shared_mapping(vma->vm !! 70 return vma->vm_flags & (VM_SHARED | VM_MAYSHARE) ? 0 : -ENOSYS;
67 } 71 }
68 72
69 static unsigned romfs_mmap_capabilities(struct 73 static unsigned romfs_mmap_capabilities(struct file *file)
70 { 74 {
71 struct mtd_info *mtd = file_inode(file 75 struct mtd_info *mtd = file_inode(file)->i_sb->s_mtd;
72 76
73 if (!mtd) 77 if (!mtd)
74 return NOMMU_MAP_COPY; 78 return NOMMU_MAP_COPY;
75 return mtd_mmap_capabilities(mtd); 79 return mtd_mmap_capabilities(mtd);
76 } 80 }
77 81
78 const struct file_operations romfs_ro_fops = { 82 const struct file_operations romfs_ro_fops = {
79 .llseek = generic_file 83 .llseek = generic_file_llseek,
80 .read_iter = generic_file 84 .read_iter = generic_file_read_iter,
81 .splice_read = filemap_spli !! 85 .splice_read = generic_file_splice_read,
82 .mmap = romfs_mmap, 86 .mmap = romfs_mmap,
83 .get_unmapped_area = romfs_get_un 87 .get_unmapped_area = romfs_get_unmapped_area,
84 .mmap_capabilities = romfs_mmap_c 88 .mmap_capabilities = romfs_mmap_capabilities,
85 }; 89 };
86 90
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