scripts: Add align for empty _app_smem region

When _app_smem region is empty, alignment is also needed. If there
is no alignment, the _app_smem_start used by arm mpu can be lower
than __rodata_region_end, and this two regions can overlap.

The Armv8-R aarch64 MPU does not allow overlapped regions.

Signed-off-by: Jaxson Han <[email protected]>

Author: povergoing

include/arch/arm64/scripts/linker.ld

@@ -218,6 +218,16 @@ SECTIONS
 #define APP_SHARED_ALIGN . = ALIGN(_region_min_align);
 #define SMEM_PARTITION_ALIGN(size) MMU_ALIGN
 
+#if defined(CONFIG_ARM_MPU)
+/*
+ * When _app_smem region is empty, alignment is also needed. If there
+ * is no alignment, the _app_smem_start used by arm mpu can be lower
+ * than __rodata_region_end, and this two regions can overlap.
+ * The Armv8-R aarch64 MPU does not allow overlapped regions.
+ */
+#define EMPTY_APP_SHARED_ALIGN APP_SHARED_ALIGN
+#endif
+
 #include <app_smem.ld>
 
     _app_smem_size = _app_smem_end - _app_smem_start;

scripts/gen_app_partitions.py

@@ -90,6 +90,9 @@
 empty_app_smem = """
 	SECTION_PROLOGUE(_APP_SMEM{1}_SECTION_NAME,,)
 	{{
+#ifdef EMPTY_APP_SHARED_ALIGN
+		EMPTY_APP_SHARED_ALIGN;
+#endif
 		_app_smem{0}_start = .;
 		_app_smem{0}_end = .;
 	}} GROUP_DATA_LINK_IN(RAMABLE_REGION, ROMABLE_REGION)