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728bbe75 DG |
1 | /* |
2 | * SRAM protect-exec region helper functions | |
3 | * | |
4 | * Copyright (C) 2017 Texas Instruments Incorporated - http://www.ti.com/ | |
5 | * Dave Gerlach | |
6 | * | |
7 | * This program is free software; you can redistribute it and/or modify | |
8 | * it under the terms of the GNU General Public License version 2 as | |
9 | * published by the Free Software Foundation. | |
10 | * | |
11 | * This program is distributed "as is" WITHOUT ANY WARRANTY of any | |
12 | * kind, whether express or implied; without even the implied warranty | |
13 | * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | * GNU General Public License for more details. | |
15 | */ | |
16 | ||
17 | #include <linux/device.h> | |
18 | #include <linux/genalloc.h> | |
056d16b2 | 19 | #include <linux/mm.h> |
728bbe75 DG |
20 | #include <linux/sram.h> |
21 | ||
056d16b2 | 22 | #include <asm/set_memory.h> |
728bbe75 DG |
23 | |
24 | #include "sram.h" | |
25 | ||
26 | static DEFINE_MUTEX(exec_pool_list_mutex); | |
27 | static LIST_HEAD(exec_pool_list); | |
28 | ||
29 | int sram_check_protect_exec(struct sram_dev *sram, struct sram_reserve *block, | |
30 | struct sram_partition *part) | |
31 | { | |
32 | unsigned long base = (unsigned long)part->base; | |
33 | unsigned long end = base + block->size; | |
34 | ||
35 | if (!PAGE_ALIGNED(base) || !PAGE_ALIGNED(end)) { | |
36 | dev_err(sram->dev, | |
37 | "SRAM pool marked with 'protect-exec' is not page aligned and will not be created.\n"); | |
38 | return -ENOMEM; | |
39 | } | |
40 | ||
41 | return 0; | |
42 | } | |
43 | ||
44 | int sram_add_protect_exec(struct sram_partition *part) | |
45 | { | |
46 | mutex_lock(&exec_pool_list_mutex); | |
47 | list_add_tail(&part->list, &exec_pool_list); | |
48 | mutex_unlock(&exec_pool_list_mutex); | |
49 | ||
50 | return 0; | |
51 | } | |
52 | ||
53 | /** | |
54 | * sram_exec_copy - copy data to a protected executable region of sram | |
55 | * | |
56 | * @pool: struct gen_pool retrieved that is part of this sram | |
57 | * @dst: Destination address for the copy, that must be inside pool | |
58 | * @src: Source address for the data to copy | |
59 | * @size: Size of copy to perform, which starting from dst, must reside in pool | |
60 | * | |
61 | * This helper function allows sram driver to act as central control location | |
62 | * of 'protect-exec' pools which are normal sram pools but are always set | |
63 | * read-only and executable except when copying data to them, at which point | |
64 | * they are set to read-write non-executable, to make sure no memory is | |
65 | * writeable and executable at the same time. This region must be page-aligned | |
66 | * and is checked during probe, otherwise page attribute manipulation would | |
67 | * not be possible. | |
68 | */ | |
69 | int sram_exec_copy(struct gen_pool *pool, void *dst, void *src, | |
70 | size_t size) | |
71 | { | |
72 | struct sram_partition *part = NULL, *p; | |
73 | unsigned long base; | |
74 | int pages; | |
75 | ||
76 | mutex_lock(&exec_pool_list_mutex); | |
77 | list_for_each_entry(p, &exec_pool_list, list) { | |
78 | if (p->pool == pool) | |
79 | part = p; | |
80 | } | |
81 | mutex_unlock(&exec_pool_list_mutex); | |
82 | ||
83 | if (!part) | |
84 | return -EINVAL; | |
85 | ||
86 | if (!addr_in_gen_pool(pool, (unsigned long)dst, size)) | |
87 | return -EINVAL; | |
88 | ||
89 | base = (unsigned long)part->base; | |
90 | pages = PAGE_ALIGN(size) / PAGE_SIZE; | |
91 | ||
92 | mutex_lock(&part->lock); | |
93 | ||
94 | set_memory_nx((unsigned long)base, pages); | |
95 | set_memory_rw((unsigned long)base, pages); | |
96 | ||
97 | memcpy(dst, src, size); | |
98 | ||
99 | set_memory_ro((unsigned long)base, pages); | |
100 | set_memory_x((unsigned long)base, pages); | |
101 | ||
102 | mutex_unlock(&part->lock); | |
103 | ||
104 | return 0; | |
105 | } | |
106 | EXPORT_SYMBOL_GPL(sram_exec_copy); |