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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122// 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);