llext: support ARC MPU

Make it so LLEXT allocates a memory region equal or greater
to the minimum size supported by the MPU, to ensure no region
overlap.

Signed-off-by: Lauren Murphy <lauren.murphy@intel.com>

subsys/llext/llext_mem.c

@@ -20,8 +20,10 @@ LOG_MODULE_DECLARE(llext, CONFIG_LLEXT_LOG_LEVEL);
 
 #ifdef CONFIG_MMU_PAGE_SIZE
 #define LLEXT_PAGE_SIZE CONFIG_MMU_PAGE_SIZE
+#elif CONFIG_ARC_MPU_VER == 2
+#define LLEXT_PAGE_SIZE 2048
 #else
-/* Arm's MPU wants a 32 byte minimum mpu region */
+/* Arm and non-v2 ARC MPUs want a 32 byte minimum MPU region */
 #define LLEXT_PAGE_SIZE 32
 #endif
 
@@ -77,7 +79,7 @@ static int llext_copy_region(struct llext_loader *ldr, struct llext *ext,
 	 * program-accessible data (not to string tables, for example).
 	 */
 	if (region->sh_flags & SHF_ALLOC) {
-		if (IS_ENABLED(CONFIG_ARM_MPU)) {
+		if (IS_ENABLED(CONFIG_ARM_MPU) || IS_ENABLED(CONFIG_ARC_MPU)) {
 			/* On ARM with an MPU, regions must be sized and
 			 * aligned to the same power of two (larger than 32).
 			 */

tests/subsys/llext/testcase.yaml

@@ -44,7 +44,9 @@ tests:
     extra_configs:
       - CONFIG_LLEXT_STORAGE_WRITABLE=n
   llext.readonly_mpu:
-    arch_allow: arm # Xtensa needs writable storage, currently not supported on RISC-V
+    arch_allow:
+      - arm # Xtensa needs writable storage, currently not supported on RISC-V
+      - arc
     filter: CONFIG_ARCH_HAS_USERSPACE
     extra_configs:
       - CONFIG_USERSPACE=y