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>
20 #include <linux/sram.h>
22 #include <asm/set_memory.h>
26 static DEFINE_MUTEX(exec_pool_list_mutex);
27 static LIST_HEAD(exec_pool_list);
29 int sram_check_protect_exec(struct sram_dev *sram, struct sram_reserve *block,
30 struct sram_partition *part)
32 unsigned long base = (unsigned long)part->base;
33 unsigned long end = base + block->size;
35 if (!PAGE_ALIGNED(base) || !PAGE_ALIGNED(end)) {
37 "SRAM pool marked with 'protect-exec' is not page aligned and will not be created.\n");
44 int sram_add_protect_exec(struct sram_partition *part)
46 mutex_lock(&exec_pool_list_mutex);
47 list_add_tail(&part->list, &exec_pool_list);
48 mutex_unlock(&exec_pool_list_mutex);
54 * sram_exec_copy - copy data to a protected executable region of sram
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
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
69 int sram_exec_copy(struct gen_pool *pool, void *dst, void *src,
72 struct sram_partition *part = NULL, *p;
76 mutex_lock(&exec_pool_list_mutex);
77 list_for_each_entry(p, &exec_pool_list, list) {
81 mutex_unlock(&exec_pool_list_mutex);
86 if (!addr_in_gen_pool(pool, (unsigned long)dst, size))
89 base = (unsigned long)part->base;
90 pages = PAGE_ALIGN(size) / PAGE_SIZE;
92 mutex_lock(&part->lock);
94 set_memory_nx((unsigned long)base, pages);
95 set_memory_rw((unsigned long)base, pages);
97 memcpy(dst, src, size);
99 set_memory_ro((unsigned long)base, pages);
100 set_memory_x((unsigned long)base, pages);
102 mutex_unlock(&part->lock);
106 EXPORT_SYMBOL_GPL(sram_exec_copy);