kernel: profiling: Expose an API call to analyze call stacks

The main, idle, interrupt and workqueue call stack definitions are not available
to applications to call stack_analyze() on, but they often require to be
measured empirically to tune their sizes in particular applications and
use cases.
This exposes a new k_call_stacks_analyze() API call that allows the
application to measure the used call stack space for the 4
kernel-defined call stacks.
Additionally for the ARC architecture the FIRQ stack is also profiled.

Change-id: I0cde149c7366cb6c4bbe8f9b0ab1cc5b56a36ed9
Signed-off-by: Carles Cufi <carles.cufi@nordicsemi.no>

include/kernel.h

@@ -102,6 +102,34 @@ enum execution_context_types {
 	K_PREEMPT_THREAD,
 };
 
+/**
+ * @defgroup profiling_apis Profiling APIs
+ * @ingroup kernel_apis
+ * @{
+ */
+
+/**
+ * @brief Analyze the main, idle, interrupt and system workqueue call stacks
+ *
+ * This routine calls @ref stack_analyze on the 4 call stacks declared and
+ * maintained by the kernel. The sizes of those 4 call stacks are defined by:
+ *
+ * CONFIG_MAIN_STACK_SIZE
+ * CONFIG_IDLE_STACK_SIZE
+ * CONFIG_ISR_STACK_SIZE
+ * CONFIG_SYSTEM_WORKQUEUE_STACK_SIZE
+ *
+ * @note CONFIG_INIT_STACKS and CONFIG_PRINTK must be set for this function to
+ * produce output.
+ *
+ * @return N/A
+ */
+extern void k_call_stacks_analyze(void);
+
+/**
+ * @} end defgroup profiling_apis
+ */
+
 /**
  * @defgroup thread_apis Thread APIs
  * @ingroup kernel_apis

kernel/init.c

@@ -25,6 +25,7 @@
 #include <offsets_short.h>
 #include <kernel.h>
 #include <misc/printk.h>
+#include <misc/stack.h>
 #include <drivers/rand32.h>
 #include <sections.h>
 #include <toolchain.h>
@@ -118,6 +119,28 @@ char __noinit __stack _interrupt_stack[CONFIG_ISR_STACK_SIZE];
 
 extern void idle(void *unused1, void *unused2, void *unused3);
 
+void k_call_stacks_analyze(void)
+{
+#if defined(CONFIG_INIT_STACKS) && defined(CONFIG_PRINTK)
+	extern char sys_work_q_stack[CONFIG_SYSTEM_WORKQUEUE_STACK_SIZE];
+#if defined(CONFIG_ARC)
+	extern char _firq_stack[CONFIG_FIRQ_STACK_SIZE];
+#endif /* CONFIG_ARC */
+
+	printk("Kernel stacks:\n");
+	stack_analyze("main     ", _main_stack, sizeof(_main_stack));
+	stack_analyze("idle     ", _idle_stack, sizeof(_idle_stack));
+#if defined(CONFIG_ARC)
+	stack_analyze("firq     ", _firq_stack, sizeof(_firq_stack));
+#endif /* CONFIG_ARC */
+	stack_analyze("interrupt", _interrupt_stack,
+		      sizeof(_interrupt_stack));
+	stack_analyze("workqueue", sys_work_q_stack,
+		      sizeof(sys_work_q_stack));
+
+#endif /* CONFIG_INIT_STACKS && CONFIG_PRINTK */
+}
+
 /**
  *
  * @brief Clear BSS

kernel/system_work_q.c

@@ -24,7 +24,7 @@
 #include <kernel.h>
 #include <init.h>
 
-static char __stack sys_work_q_stack[CONFIG_SYSTEM_WORKQUEUE_STACK_SIZE];
+char __noinit __stack sys_work_q_stack[CONFIG_SYSTEM_WORKQUEUE_STACK_SIZE];
 
 struct k_work_q k_sys_work_q;