esp32: Refactor backtrace and add esp_backtrace_print()

This commit refactors backtracing within the panic handler so that a common
function esp_backtrace_get_next_frame() is used iteratively to traverse a
callstack.

A esp_backtrace_print() function has also be added that allows the printing
of a backtrace at runtime. The esp_backtrace_print() function allows unity to
print the backtrace of failed test cases and jump back to the main test menu
without the need reset the chip. esp_backtrace_print() can also be used as a
debugging function by users.

- esp_stack_ptr_is_sane() moved to soc_memory_layout.h
- removed uncessary includes of "esp_debug_helpers.h"

components/unity/CMakeLists.txt

@@ -4,6 +4,10 @@ set(COMPONENT_SRCS "unity/src/unity.c"
 set(COMPONENT_ADD_INCLUDEDIRS "include"
                               "unity/src")
 
+if(CONFIG_UNITY_ENABLE_BACKTRACE_ON_FAIL)
+    list(APPEND COMPONENT_PRIV_INCLUDEDIRS "include/priv")
+endif()
+
 if(CONFIG_UNITY_ENABLE_IDF_TEST_RUNNER)
     list(APPEND COMPONENT_SRCS "unity_runner.c")
 endif()

components/unity/Kconfig

@@ -42,4 +42,12 @@ menu "Unity unit testing library"
             the build. These provide an optional set of macros and functions to
             implement test groups.
 
-endmenu # "Unity unit testing library"
+    config UNITY_ENABLE_BACKTRACE_ON_FAIL
+        bool "Print a backtrace when a unit test fails"
+        default n
+        help
+            If set, the unity framework will print the backtrace information before
+            jumping back to the test menu. The jumping is usually occurs in assert
+            functions such as TEST_ASSERT, TEST_FAIL etc.
+
+endmenu # "Unity unit testing library"

components/unity/component.mk

@@ -9,6 +9,10 @@ endif
 COMPONENT_ADD_INCLUDEDIRS = include unity/src
 COMPONENT_SRCDIRS = unity/src .
 
+ifdef CONFIG_UNITY_ENABLE_BACKTRACE_ON_FAIL
+COMPONENT_PRIV_INCLUDEDIRS += include/priv
+endif
+
 ifndef CONFIG_UNITY_ENABLE_IDF_TEST_RUNNER
 COMPONENT_OBJEXCLUDE += unity_runner.o
 endif

components/unity/include/priv/setjmp.h

@@ -0,0 +1,14 @@
+#include_next <setjmp.h>
+#include "esp_debug_helpers.h"
+
+/*
+ * This is the middle layer of setjmp to be used with the unity.
+ */
+
+/** Insert backtrace before longjmp (TEST_ABORT).
+ *
+ * Currently we only do long jump before test is ignored or failed.
+ * If this is also called when test pass, we may need to add some check before
+ * backtrace is called.
+ */
+#define longjmp(buf, val) do {esp_backtrace_print(100); longjmp(buf, val);} while(0)