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path: root/drivers/misc/sram-exec.c
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Diffstat (limited to 'drivers/misc/sram-exec.c')
-rw-r--r--drivers/misc/sram-exec.c27
1 files changed, 20 insertions, 7 deletions
diff --git a/drivers/misc/sram-exec.c b/drivers/misc/sram-exec.c
index 3d528a13b8fc..426ad912b441 100644
--- a/drivers/misc/sram-exec.c
+++ b/drivers/misc/sram-exec.c
@@ -19,6 +19,7 @@
#include <linux/mm.h>
#include <linux/sram.h>
+#include <asm/fncpy.h>
#include <asm/set_memory.h>
#include "sram.h"
@@ -58,20 +59,32 @@ int sram_add_protect_exec(struct sram_partition *part)
* @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.
+ * 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.
*/
-int sram_exec_copy(struct gen_pool *pool, void *dst, void *src,
- size_t size)
+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) {
@@ -81,10 +94,10 @@ int sram_exec_copy(struct gen_pool *pool, void *dst, void *src,
mutex_unlock(&exec_pool_list_mutex);
if (!part)
- return -EINVAL;
+ return NULL;
if (!addr_in_gen_pool(pool, (unsigned long)dst, size))
- return -EINVAL;
+ return NULL;
base = (unsigned long)part->base;
pages = PAGE_ALIGN(size) / PAGE_SIZE;
@@ -94,13 +107,13 @@ int sram_exec_copy(struct gen_pool *pool, void *dst, void *src,
set_memory_nx((unsigned long)base, pages);
set_memory_rw((unsigned long)base, pages);
- memcpy(dst, src, size);
+ 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 0;
+ return dst_cpy;
}
EXPORT_SYMBOL_GPL(sram_exec_copy);