/*
|
* 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/mm.h>
|
#include <linux/sram.h>
|
|
#include <asm/fncpy.h>
|
#include <asm/set_memory.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;
|
|
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 (!addr_in_gen_pool(pool, (unsigned long)dst, size))
|
return NULL;
|
|
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);
|
|
dst_cpy = fncpy(dst, src, size);
|
|
set_memory_ro((unsigned long)base, pages);
|
set_memory_x((unsigned long)base, pages);
|
|
mutex_unlock(&part->lock);
|
|
return dst_cpy;
|
}
|
EXPORT_SYMBOL_GPL(sram_exec_copy);
|
