2 * SRAM protect-exec region helper functions
4 * Copyright (C) 2017 Texas Instruments Incorporated - http://www.ti.com/
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.
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.
17 #include <linux/device.h>
18 #include <linux/genalloc.h>
19 #include <linux/sram.h>
21 #include <asm/cacheflush.h>
25 static DEFINE_MUTEX(exec_pool_list_mutex);
26 static LIST_HEAD(exec_pool_list);
28 int sram_check_protect_exec(struct sram_dev *sram, struct sram_reserve *block,
29 struct sram_partition *part)
31 unsigned long base = (unsigned long)part->base;
32 unsigned long end = base + block->size;
34 if (!PAGE_ALIGNED(base) || !PAGE_ALIGNED(end)) {
36 "SRAM pool marked with 'protect-exec' is not page aligned and will not be created.\n");
43 int sram_add_protect_exec(struct sram_partition *part)
45 mutex_lock(&exec_pool_list_mutex);
46 list_add_tail(&part->list, &exec_pool_list);
47 mutex_unlock(&exec_pool_list_mutex);
53 * sram_exec_copy - copy data to a protected executable region of sram
55 * @pool: struct gen_pool retrieved that is part of this sram
56 * @dst: Destination address for the copy, that must be inside pool
57 * @src: Source address for the data to copy
58 * @size: Size of copy to perform, which starting from dst, must reside in pool
60 * This helper function allows sram driver to act as central control location
61 * of 'protect-exec' pools which are normal sram pools but are always set
62 * read-only and executable except when copying data to them, at which point
63 * they are set to read-write non-executable, to make sure no memory is
64 * writeable and executable at the same time. This region must be page-aligned
65 * and is checked during probe, otherwise page attribute manipulation would
68 int sram_exec_copy(struct gen_pool *pool, void *dst, void *src,
71 struct sram_partition *part = NULL, *p;
75 mutex_lock(&exec_pool_list_mutex);
76 list_for_each_entry(p, &exec_pool_list, list) {
80 mutex_unlock(&exec_pool_list_mutex);
85 if (!addr_in_gen_pool(pool, (unsigned long)dst, size))
88 base = (unsigned long)part->base;
89 pages = PAGE_ALIGN(size) / PAGE_SIZE;
91 mutex_lock(&part->lock);
93 set_memory_nx((unsigned long)base, pages);
94 set_memory_rw((unsigned long)base, pages);
96 memcpy(dst, src, size);
98 set_memory_ro((unsigned long)base, pages);
99 set_memory_x((unsigned long)base, pages);
101 mutex_unlock(&part->lock);
105 EXPORT_SYMBOL_GPL(sram_exec_copy);