diff options
Diffstat (limited to 'drivers/misc/sram-exec.c')
| -rw-r--r-- | drivers/misc/sram-exec.c | 27 |
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); |