tests: kernel: add simple test for the ramfunc feature

This commit contributes a simple test for
the ARM RAMFUNC feature.

Signed-off-by: Ioannis Glaropoulos <Ioannis.Glaropoulos@nordicsemi.no>

tests/kernel/arm_ramfunc/CMakeLists.txt

@@ -0,0 +1,9 @@
+# SPDX-License-Identifier: Apache-2.0
+
+cmake_minimum_required(VERSION 3.13.1)
+
+include($ENV{ZEPHYR_BASE}/cmake/app/boilerplate.cmake NO_POLICY_SCOPE)
+project(arm_zero_latency_irqs)
+
+FILE(GLOB app_sources src/*.c)
+target_sources(app PRIVATE ${app_sources})

tests/kernel/arm_ramfunc/README.txt

@@ -0,0 +1,45 @@
+Title: Test to verify code execution from SRAM for XIP images (ARM Only)
+
+Description:
+
+This test verifies that we can define functions in SRAM (and
+sucessfully execute them from SRAM) in ARM XIP images. It
+also verifies that the .ramfunc section is accessible by
+nPRIV code when building with support for user mode
+(CONFIG_USERSPACE=y). Only for ARM Cortex-M targets.
+
+---------------------------------------------------------------------------
+
+Building and Running Project:
+
+This project outputs to the console.  It can be built and executed on QEMU as
+follows:
+
+    ninja/make run
+
+---------------------------------------------------------------------------
+
+Troubleshooting:
+
+Problems caused by out-dated project information can be addressed by
+issuing one of the following commands then rebuilding the project:
+
+    ninja/make clean    # discard results of previous builds
+                        # but keep existing configuration info
+or
+    ninja/make pristine # discard results of previous builds
+                        # and restore pre-defined configuration info
+
+---------------------------------------------------------------------------
+
+Sample Output:
+
+***** Booting Zephyr OS build zephyr-v1.14.0-1726-gb95a71960622 *****
+Running test suite arm_ramfunc
+===================================================================
+starting test - test_arm_ramfunc
+PASS - test_arm_ramfunc
+===================================================================
+Test suite arm_ramfunc succeeded
+===================================================================
+PROJECT EXECUTION SUCCESSFUL

tests/kernel/arm_ramfunc/prj.conf

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+CONFIG_ZTEST=y
+CONFIG_USERSPACE=y

tests/kernel/arm_ramfunc/src/arm_ramfunc.c

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+/*
+ * Copyright (c) 2019 Nordic Semiconductor ASA.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <ztest.h>
+#include <linker/linker-defs.h>
+#include <syscall_handler.h>
+
+static volatile int test_flag;
+
+__ramfunc static void arm_ram_function(void)
+{
+	test_flag = 1;
+}
+
+void test_arm_ramfunc(void)
+{
+	zassert_true(test_flag == 0, "Test flag not initialized to zero");
+
+	/* Verify that the .ramfunc section is not empty, it is located
+	 * inside SRAM, and that arm_ram_function(.) is located inside
+	 * the .ramfunc section.
+	 */
+	zassert_true((u32_t)&_ramfunc_ram_size != 0,
+		".ramfunc linker section is empty");
+	zassert_true(((u32_t)&_ramfunc_ram_start >= (u32_t)&_image_ram_start)
+			&& ((u32_t)&_ramfunc_ram_end < (u32_t)&_image_ram_end),
+			".ramfunc linker section not in RAM");
+	zassert_true(
+		(((u32_t)&_ramfunc_ram_start) <= (u32_t)arm_ram_function) &&
+		(((u32_t)&_ramfunc_ram_end) > (u32_t)arm_ram_function),
+		"arm_ram_function not loaded into .ramfunc");
+
+	/* If we build with User Mode support, verify that the
+	 * arm_ram_function(.) is user (read) accessible.
+	 */
+#if defined(CONFIG_USERSPACE)
+	zassert_true(z_arch_buffer_validate((void *)&_ramfunc_ram_start,
+			(size_t)&_ramfunc_ram_size, 0) == 0 /* Success */,
+		".ramfunc section not user accessible");
+#endif /* CONFIG_USERSPACE */
+
+	/* Execute the function from SRAM. */
+	arm_ram_function();
+
+	/* Verify that the function is executed successfully. */
+	zassert_true(test_flag = 1,
+		"arm_ram_function() execution failed.");
+}
+/**
+ * @}
+ */

tests/kernel/arm_ramfunc/src/main.c

@@ -0,0 +1,20 @@
+/*
+ * Copyright (c) 2019 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#if !defined(CONFIG_CPU_CORTEX_M)
+  #error test can only run on Cortex-M MCUs
+#endif
+
+#include <ztest.h>
+
+extern void test_arm_ramfunc(void);
+
+void test_main(void)
+{
+	ztest_test_suite(arm_ramfunc,
+		ztest_unit_test(test_arm_ramfunc));
+	ztest_run_test_suite(arm_ramfunc);
+}

tests/kernel/arm_ramfunc/testcase.yaml

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+tests:
+  arch.ramfunc:
+    filter: CONFIG_ARCH_HAS_RAMFUNC_SUPPORT
+    tags: arm userspace
+    arch_whitelist: arm