diff options
| -rw-r--r-- | drivers/misc/sram-exec.c | 105 | ||||
| -rw-r--r-- | drivers/misc/sram.h | 18 | ||||
| -rw-r--r-- | include/linux/sram.h | 27 |
3 files changed, 150 insertions, 0 deletions
diff --git a/drivers/misc/sram-exec.c b/drivers/misc/sram-exec.c new file mode 100644 index 000000000000..ac522417c462 --- /dev/null +++ b/drivers/misc/sram-exec.c @@ -0,0 +1,105 @@ +/* + * SRAM protect-exec region helper functions + * + * Copyright (C) 2017 Texas Instruments Incorporated - http://www.ti.com/ + * Dave Gerlach + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * This program is distributed "as is" WITHOUT ANY WARRANTY of any + * kind, whether express or implied; without even the implied warranty + * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ + +#include <linux/device.h> +#include <linux/genalloc.h> +#include <linux/sram.h> + +#include <asm/cacheflush.h> + +#include "sram.h" + +static DEFINE_MUTEX(exec_pool_list_mutex); +static LIST_HEAD(exec_pool_list); + +int sram_check_protect_exec(struct sram_dev *sram, struct sram_reserve *block, + struct sram_partition *part) +{ + unsigned long base = (unsigned long)part->base; + unsigned long end = base + block->size; + + if (!PAGE_ALIGNED(base) || !PAGE_ALIGNED(end)) { + dev_err(sram->dev, + "SRAM pool marked with 'protect-exec' is not page aligned and will not be created.\n"); + return -ENOMEM; + } + + return 0; +} + +int sram_add_protect_exec(struct sram_partition *part) +{ + mutex_lock(&exec_pool_list_mutex); + list_add_tail(&part->list, &exec_pool_list); + mutex_unlock(&exec_pool_list_mutex); + + return 0; +} + +/** + * sram_exec_copy - copy data to a protected executable region of sram + * + * @pool: struct gen_pool retrieved that is part of this sram + * @dst: Destination address for the copy, that must be inside pool + * @src: Source address for the data to copy + * @size: Size of copy to perform, which starting from dst, must reside in pool + * + * This helper function allows sram driver to act as central control location + * of 'protect-exec' pools which are normal sram pools but are always set + * read-only and executable except when copying data to them, at which point + * they are set to read-write non-executable, to make sure no memory is + * writeable and executable at the same time. This region must be page-aligned + * and is checked during probe, otherwise page attribute manipulation would + * not be possible. + */ +int sram_exec_copy(struct gen_pool *pool, void *dst, void *src, + size_t size) +{ + struct sram_partition *part = NULL, *p; + unsigned long base; + int pages; + + mutex_lock(&exec_pool_list_mutex); + list_for_each_entry(p, &exec_pool_list, list) { + if (p->pool == pool) + part = p; + } + mutex_unlock(&exec_pool_list_mutex); + + if (!part) + return -EINVAL; + + if (!addr_in_gen_pool(pool, (unsigned long)dst, size)) + return -EINVAL; + + base = (unsigned long)part->base; + pages = PAGE_ALIGN(size) / PAGE_SIZE; + + mutex_lock(&part->lock); + + set_memory_nx((unsigned long)base, pages); + set_memory_rw((unsigned long)base, pages); + + memcpy(dst, src, size); + + set_memory_ro((unsigned long)base, pages); + set_memory_x((unsigned long)base, pages); + + mutex_unlock(&part->lock); + + return 0; +} +EXPORT_SYMBOL_GPL(sram_exec_copy); diff --git a/drivers/misc/sram.h b/drivers/misc/sram.h index 52501a84468c..b268cd3f55bb 100644 --- a/drivers/misc/sram.h +++ b/drivers/misc/sram.h @@ -36,4 +36,22 @@ struct sram_reserve { bool pool; const char *label; }; + +#ifdef CONFIG_SRAM_EXEC +int sram_check_protect_exec(struct sram_dev *sram, struct sram_reserve *block, + struct sram_partition *part); +int sram_add_protect_exec(struct sram_partition *part); +#else +static inline int sram_check_protect_exec(struct sram_dev *sram, + struct sram_reserve *block, + struct sram_partition *part) +{ + return -ENODEV; +} + +static inline int sram_add_protect_exec(struct sram_partition *part) +{ + return -ENODEV; +} +#endif /* CONFIG_SRAM_EXEC */ #endif /* __SRAM_H */ diff --git a/include/linux/sram.h b/include/linux/sram.h new file mode 100644 index 000000000000..c97dcbe8ce25 --- /dev/null +++ b/include/linux/sram.h @@ -0,0 +1,27 @@ +/* + * Generic SRAM Driver Interface + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License as + * published by the Free Software Foundation version 2. + * + * This program is distributed "as is" WITHOUT ANY WARRANTY of any + * kind, whether express or implied; without even the implied warranty + * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ +#ifndef __LINUX_SRAM_H__ +#define __LINUX_SRAM_H__ + +struct gen_pool; + +#ifdef CONFIG_SRAM_EXEC +int sram_exec_copy(struct gen_pool *pool, void *dst, void *src, size_t size); +#else +static inline int sram_exec_copy(struct gen_pool *pool, void *dst, void *src, + size_t size) +{ + return -ENODEV; +} +#endif /* CONFIG_SRAM_EXEC */ +#endif /* __LINUX_SRAM_H__ */ |