// SPDX-License-Identifier: GPL-2.0-only/* * SRAM protect-exec region helper functions * * Copyright (C) 2017 Texas Instruments Incorporated - https://www.ti.com/ *	Dave Gerlach */ #include <linux/device.h>#include <linux/genalloc.h>#include <linux/mm.h>#include <linux/sram.h>#include <linux/set_memory.h> #include <asm/fncpy.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 * * Return: Address for copied data that can safely be called through function *	   pointer, or NULL if problem. * * 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. Care must be taken to only call the returned address as * dst address is not guaranteed to be safely callable. * * NOTE: This function uses the fncpy macro to move code to the executable * region. Some architectures have strict requirements for relocating * executable code, so fncpy is a macro that must be defined by any arch * making use of this functionality that guarantees a safe copy of exec * data and returns a safe address that can be called as a C function * pointer. */void *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;	void *dst_cpy;	int ret; 	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 NULL; 	if (!gen_pool_has_addr(pool, (unsigned long)dst, size))		return NULL; 	base = (unsigned long)part->base;	pages = PAGE_ALIGN(size) / PAGE_SIZE; 	mutex_lock(&part->lock); 	ret = set_memory_nx((unsigned long)base, pages);	if (ret)		goto error_out;	ret = set_memory_rw((unsigned long)base, pages);	if (ret)		goto error_out; 	dst_cpy = fncpy(dst, src, size); 	ret = set_memory_rox((unsigned long)base, pages);	if (ret)		goto error_out; 	mutex_unlock(&part->lock); 	return dst_cpy; error_out:	mutex_unlock(&part->lock);	return NULL;}EXPORT_SYMBOL_GPL(sram_exec_copy);