xtensa: userspace: only write 0xAA to stack if INIT_STACKS

Only clear the user stack to 0xAA if CONFIG_INIT_STACKS is
enabled. Otherwise, write 0x00 as if the stack is in BSS.

Signed-off-by: Daniel Leung <daniel.leung@intel.com>

Author: dcpleung

arch/xtensa/core/xtensa_mmu.c

@@ -1057,8 +1057,9 @@ static inline int reset_region(uint32_t *ptables, uintptr_t start, size_t size,
 
 void xtensa_user_stack_perms(struct k_thread *thread)
 {
-	(void)memset((void *)thread->stack_info.start, 0xAA,
-		thread->stack_info.size - thread->stack_info.delta);
+	(void)memset((void *)thread->stack_info.start,
+		     (IS_ENABLED(CONFIG_INIT_STACKS)) ? 0xAA : 0x00,
+		     thread->stack_info.size - thread->stack_info.delta);
 
 	update_region(thread_page_tables_get(thread),
 		      thread->stack_info.start, thread->stack_info.size,