linux/drivers/misc/sram.c
Dave Gerlach 37afff0d87 misc: sram: Integrate protect-exec reserved sram area type
Introduce a new "protect-exec" reserved sram area type which is
makes use of the the existing functionality provided for the "pool"
sram region type for use with the genalloc framework and with the
added requirement that it be maintained as read-only and executable
while allowing for an arbitrary number of drivers to share the space.

This introduces a common way to maintain a region of sram as read-only
and executable and also introduces a helper function, sram_exec_copy,
which allows for copying data to this protected region while maintaining
locking to avoid conflicts between multiple users of the same space. A
region of memory that is marked with the "protect-exec" flag in the
device tree also has the requirement of providing a page aligned block
of memory so that the page attribute manipulation does not affect
surrounding regions.

Also, selectively enable this only for builds that support set_memory_*
calls, for now just ARM, through the use of Kconfig.

Signed-off-by: Dave Gerlach <d-gerlach@ti.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-01-25 11:48:03 +01:00

449 lines
11 KiB
C

/*
* Generic on-chip SRAM allocation driver
*
* Copyright (C) 2012 Philipp Zabel, Pengutronix
*
* 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; either version 2
* of the License, or (at your option) any later version.
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
* MA 02110-1301, USA.
*/
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/genalloc.h>
#include <linux/io.h>
#include <linux/list_sort.h>
#include <linux/of_address.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
#include <linux/slab.h>
#include <linux/mfd/syscon.h>
#include <soc/at91/atmel-secumod.h>
#include "sram.h"
#define SRAM_GRANULARITY 32
static ssize_t sram_read(struct file *filp, struct kobject *kobj,
struct bin_attribute *attr,
char *buf, loff_t pos, size_t count)
{
struct sram_partition *part;
part = container_of(attr, struct sram_partition, battr);
mutex_lock(&part->lock);
memcpy_fromio(buf, part->base + pos, count);
mutex_unlock(&part->lock);
return count;
}
static ssize_t sram_write(struct file *filp, struct kobject *kobj,
struct bin_attribute *attr,
char *buf, loff_t pos, size_t count)
{
struct sram_partition *part;
part = container_of(attr, struct sram_partition, battr);
mutex_lock(&part->lock);
memcpy_toio(part->base + pos, buf, count);
mutex_unlock(&part->lock);
return count;
}
static int sram_add_pool(struct sram_dev *sram, struct sram_reserve *block,
phys_addr_t start, struct sram_partition *part)
{
int ret;
part->pool = devm_gen_pool_create(sram->dev, ilog2(SRAM_GRANULARITY),
NUMA_NO_NODE, block->label);
if (IS_ERR(part->pool))
return PTR_ERR(part->pool);
ret = gen_pool_add_virt(part->pool, (unsigned long)part->base, start,
block->size, NUMA_NO_NODE);
if (ret < 0) {
dev_err(sram->dev, "failed to register subpool: %d\n", ret);
return ret;
}
return 0;
}
static int sram_add_export(struct sram_dev *sram, struct sram_reserve *block,
phys_addr_t start, struct sram_partition *part)
{
sysfs_bin_attr_init(&part->battr);
part->battr.attr.name = devm_kasprintf(sram->dev, GFP_KERNEL,
"%llx.sram",
(unsigned long long)start);
if (!part->battr.attr.name)
return -ENOMEM;
part->battr.attr.mode = S_IRUSR | S_IWUSR;
part->battr.read = sram_read;
part->battr.write = sram_write;
part->battr.size = block->size;
return device_create_bin_file(sram->dev, &part->battr);
}
static int sram_add_partition(struct sram_dev *sram, struct sram_reserve *block,
phys_addr_t start)
{
int ret;
struct sram_partition *part = &sram->partition[sram->partitions];
mutex_init(&part->lock);
part->base = sram->virt_base + block->start;
if (block->pool) {
ret = sram_add_pool(sram, block, start, part);
if (ret)
return ret;
}
if (block->export) {
ret = sram_add_export(sram, block, start, part);
if (ret)
return ret;
}
if (block->protect_exec) {
ret = sram_check_protect_exec(sram, block, part);
if (ret)
return ret;
ret = sram_add_pool(sram, block, start, part);
if (ret)
return ret;
sram_add_protect_exec(part);
}
sram->partitions++;
return 0;
}
static void sram_free_partitions(struct sram_dev *sram)
{
struct sram_partition *part;
if (!sram->partitions)
return;
part = &sram->partition[sram->partitions - 1];
for (; sram->partitions; sram->partitions--, part--) {
if (part->battr.size)
device_remove_bin_file(sram->dev, &part->battr);
if (part->pool &&
gen_pool_avail(part->pool) < gen_pool_size(part->pool))
dev_err(sram->dev, "removed pool while SRAM allocated\n");
}
}
static int sram_reserve_cmp(void *priv, struct list_head *a,
struct list_head *b)
{
struct sram_reserve *ra = list_entry(a, struct sram_reserve, list);
struct sram_reserve *rb = list_entry(b, struct sram_reserve, list);
return ra->start - rb->start;
}
static int sram_reserve_regions(struct sram_dev *sram, struct resource *res)
{
struct device_node *np = sram->dev->of_node, *child;
unsigned long size, cur_start, cur_size;
struct sram_reserve *rblocks, *block;
struct list_head reserve_list;
unsigned int nblocks, exports = 0;
const char *label;
int ret = 0;
INIT_LIST_HEAD(&reserve_list);
size = resource_size(res);
/*
* We need an additional block to mark the end of the memory region
* after the reserved blocks from the dt are processed.
*/
nblocks = (np) ? of_get_available_child_count(np) + 1 : 1;
rblocks = kzalloc((nblocks) * sizeof(*rblocks), GFP_KERNEL);
if (!rblocks)
return -ENOMEM;
block = &rblocks[0];
for_each_available_child_of_node(np, child) {
struct resource child_res;
ret = of_address_to_resource(child, 0, &child_res);
if (ret < 0) {
dev_err(sram->dev,
"could not get address for node %s\n",
child->full_name);
goto err_chunks;
}
if (child_res.start < res->start || child_res.end > res->end) {
dev_err(sram->dev,
"reserved block %s outside the sram area\n",
child->full_name);
ret = -EINVAL;
goto err_chunks;
}
block->start = child_res.start - res->start;
block->size = resource_size(&child_res);
list_add_tail(&block->list, &reserve_list);
if (of_find_property(child, "export", NULL))
block->export = true;
if (of_find_property(child, "pool", NULL))
block->pool = true;
if (of_find_property(child, "protect-exec", NULL))
block->protect_exec = true;
if ((block->export || block->pool || block->protect_exec) &&
block->size) {
exports++;
label = NULL;
ret = of_property_read_string(child, "label", &label);
if (ret && ret != -EINVAL) {
dev_err(sram->dev,
"%s has invalid label name\n",
child->full_name);
goto err_chunks;
}
if (!label)
label = child->name;
block->label = devm_kstrdup(sram->dev,
label, GFP_KERNEL);
if (!block->label) {
ret = -ENOMEM;
goto err_chunks;
}
dev_dbg(sram->dev, "found %sblock '%s' 0x%x-0x%x\n",
block->export ? "exported " : "", block->label,
block->start, block->start + block->size);
} else {
dev_dbg(sram->dev, "found reserved block 0x%x-0x%x\n",
block->start, block->start + block->size);
}
block++;
}
child = NULL;
/* the last chunk marks the end of the region */
rblocks[nblocks - 1].start = size;
rblocks[nblocks - 1].size = 0;
list_add_tail(&rblocks[nblocks - 1].list, &reserve_list);
list_sort(NULL, &reserve_list, sram_reserve_cmp);
if (exports) {
sram->partition = devm_kzalloc(sram->dev,
exports * sizeof(*sram->partition),
GFP_KERNEL);
if (!sram->partition) {
ret = -ENOMEM;
goto err_chunks;
}
}
cur_start = 0;
list_for_each_entry(block, &reserve_list, list) {
/* can only happen if sections overlap */
if (block->start < cur_start) {
dev_err(sram->dev,
"block at 0x%x starts after current offset 0x%lx\n",
block->start, cur_start);
ret = -EINVAL;
sram_free_partitions(sram);
goto err_chunks;
}
if ((block->export || block->pool || block->protect_exec) &&
block->size) {
ret = sram_add_partition(sram, block,
res->start + block->start);
if (ret) {
sram_free_partitions(sram);
goto err_chunks;
}
}
/* current start is in a reserved block, so continue after it */
if (block->start == cur_start) {
cur_start = block->start + block->size;
continue;
}
/*
* allocate the space between the current starting
* address and the following reserved block, or the
* end of the region.
*/
cur_size = block->start - cur_start;
dev_dbg(sram->dev, "adding chunk 0x%lx-0x%lx\n",
cur_start, cur_start + cur_size);
ret = gen_pool_add_virt(sram->pool,
(unsigned long)sram->virt_base + cur_start,
res->start + cur_start, cur_size, -1);
if (ret < 0) {
sram_free_partitions(sram);
goto err_chunks;
}
/* next allocation after this reserved block */
cur_start = block->start + block->size;
}
err_chunks:
if (child)
of_node_put(child);
kfree(rblocks);
return ret;
}
static int atmel_securam_wait(void)
{
struct regmap *regmap;
u32 val;
regmap = syscon_regmap_lookup_by_compatible("atmel,sama5d2-secumod");
if (IS_ERR(regmap))
return -ENODEV;
return regmap_read_poll_timeout(regmap, AT91_SECUMOD_RAMRDY, val,
val & AT91_SECUMOD_RAMRDY_READY,
10000, 500000);
}
static const struct of_device_id sram_dt_ids[] = {
{ .compatible = "mmio-sram" },
{ .compatible = "atmel,sama5d2-securam", .data = atmel_securam_wait },
{}
};
static int sram_probe(struct platform_device *pdev)
{
struct sram_dev *sram;
struct resource *res;
size_t size;
int ret;
int (*init_func)(void);
sram = devm_kzalloc(&pdev->dev, sizeof(*sram), GFP_KERNEL);
if (!sram)
return -ENOMEM;
sram->dev = &pdev->dev;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!res) {
dev_err(sram->dev, "found no memory resource\n");
return -EINVAL;
}
size = resource_size(res);
if (!devm_request_mem_region(sram->dev, res->start, size, pdev->name)) {
dev_err(sram->dev, "could not request region for resource\n");
return -EBUSY;
}
if (of_property_read_bool(pdev->dev.of_node, "no-memory-wc"))
sram->virt_base = devm_ioremap(sram->dev, res->start, size);
else
sram->virt_base = devm_ioremap_wc(sram->dev, res->start, size);
if (!sram->virt_base)
return -ENOMEM;
sram->pool = devm_gen_pool_create(sram->dev, ilog2(SRAM_GRANULARITY),
NUMA_NO_NODE, NULL);
if (IS_ERR(sram->pool))
return PTR_ERR(sram->pool);
ret = sram_reserve_regions(sram, res);
if (ret)
return ret;
sram->clk = devm_clk_get(sram->dev, NULL);
if (IS_ERR(sram->clk))
sram->clk = NULL;
else
clk_prepare_enable(sram->clk);
platform_set_drvdata(pdev, sram);
init_func = of_device_get_match_data(&pdev->dev);
if (init_func) {
ret = init_func();
if (ret)
return ret;
}
dev_dbg(sram->dev, "SRAM pool: %zu KiB @ 0x%p\n",
gen_pool_size(sram->pool) / 1024, sram->virt_base);
return 0;
}
static int sram_remove(struct platform_device *pdev)
{
struct sram_dev *sram = platform_get_drvdata(pdev);
sram_free_partitions(sram);
if (gen_pool_avail(sram->pool) < gen_pool_size(sram->pool))
dev_err(sram->dev, "removed while SRAM allocated\n");
if (sram->clk)
clk_disable_unprepare(sram->clk);
return 0;
}
static struct platform_driver sram_driver = {
.driver = {
.name = "sram",
.of_match_table = sram_dt_ids,
},
.probe = sram_probe,
.remove = sram_remove,
};
static int __init sram_init(void)
{
return platform_driver_register(&sram_driver);
}
postcore_initcall(sram_init);