test: Add on-device MPU unit test

BRANCH=none
BUG=b:151105339, b:155229277
TEST=make BOARD=bloonchipper test-mpu -j && \
 ./util/flash_jlink.py --board bloonchipper \
 --image ./build/bloonchipper/mpu/mpu.bin
 => On console: "runtest"
    => All tests pass, except last which correctly panics:
       Data access violation, mfar = 20000000

Signed-off-by: Tom Hughes <tomhughes@chromium.org>
Change-Id: I1c759f50da5075b1e9027cdba253d8c06843be5a
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2202852
Commit-Queue: Yicheng Li <yichengli@chromium.org>
Tested-by: Yicheng Li <yichengli@chromium.org>
Reviewed-by: Paul Fagerburg <pfagerburg@chromium.org>

board/hatch_fp/build.mk

@@ -15,6 +15,7 @@ test-list-y=\
        aes \
        compile_time_macros \
        crc32 \
+       mpu \
        mutex \
        pingpong \
        rollback \

board/nocturne_fp/build.mk

@@ -16,6 +16,7 @@ test-list-y=\
        aes \
        compile_time_macros \
        crc32 \
+       mpu \
        mutex \
        pingpong \
        rollback \

board/nucleo-f412zg/build.mk

@@ -13,6 +13,7 @@ test-list-y=\
        aes \
        compile_time_macros \
        crc32 \
+       mpu \
        mutex \
        pingpong \
        rollback \

board/nucleo-h743zi/build.mk

@@ -13,6 +13,7 @@ test-list-y=\
        aes \
        compile_time_macros \
        crc32 \
+       mpu \
        mutex \
        pingpong \
        rollback \

core/cortex-m/mpu.c

@@ -65,6 +65,9 @@ int mpu_update_region(uint8_t region, uint32_t addr, uint8_t size_bit,
 	if (!is_aligned(addr, BIT(size_bit)))
 		return -EC_ERROR_INVAL;
 
+	if (region >= mpu_num_regions())
+		return -EC_ERROR_INVAL;
+
 	asm volatile("isb; dsb;");
 
 	MPU_NUMBER = region;

test/build.mk

@@ -150,6 +150,7 @@ motion_lid-y=motion_lid.o
 motion_sense_fifo-y=motion_sense_fifo.o
 online_calibration-y=online_calibration.o
 kasa-y=kasa.o
+mpu-y=mpu.o
 mutex-y=mutex.o
 newton_fit-y=newton_fit.o
 pingpong-y=pingpong.o

test/mpu.c

@@ -0,0 +1,127 @@
+/* Copyright 2020 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include <stdbool.h>
+#include "mpu.h"
+#include "mpu_private.h"
+#include "test_util.h"
+
+struct mpu_info {
+	bool has_mpu;
+	int num_mpu_regions;
+	bool mpu_is_unified;
+};
+
+#if defined(CHIP_VARIANT_STM32F412)
+struct mpu_info mpu_info = {
+	.has_mpu = true,
+	.num_mpu_regions = 8,
+	.mpu_is_unified = true
+};
+#elif defined(CHIP_VARIANT_STM32H7X3)
+struct mpu_info mpu_info = {
+	.has_mpu = true,
+	.num_mpu_regions = 16,
+	.mpu_is_unified = true
+};
+#else
+#error "MPU info not defined for this chip. Please add it."
+#endif
+
+test_static int test_mpu_info(void)
+{
+	TEST_EQ(mpu_num_regions(), mpu_info.num_mpu_regions, "%d");
+	TEST_EQ(has_mpu(), mpu_info.has_mpu, "%d");
+	TEST_EQ(mpu_is_unified(), mpu_info.mpu_is_unified, "%d");
+	return EC_SUCCESS;
+}
+
+test_static int reset_mpu(void)
+{
+	int i;
+
+	mpu_disable();
+
+	for (i = 0; i < mpu_info.num_mpu_regions; ++i) {
+		/*
+		 * Disable all regions.
+		 *
+		 * We use the smallest possible size (32 bytes), but it
+		 * doesn't really matter since the regions are disabled.
+		 */
+		TEST_EQ(mpu_config_region(i, 0, 32, 0, 0), EC_SUCCESS, "%d");
+	}
+
+	mpu_enable();
+
+	return EC_SUCCESS;
+}
+
+test_static int test_mpu_update_region_valid_region(void)
+{
+	volatile char data __maybe_unused;
+
+	char * const ram_base = (char * const)CONFIG_RAM_BASE;
+	const uint8_t size_bit = 5;
+	uint16_t mpu_attr = MPU_ATTR_NO_NO;
+
+	/*
+	 * Initial read should work. MPU is not protecting the given address.
+	 */
+	data = ram_base[0];
+
+	TEST_EQ(mpu_update_region(0, (uint32_t)ram_base, size_bit, mpu_attr, 1,
+				  0),
+		EC_SUCCESS, "%d");
+
+	/* This panics with a data violation at CONFIG_RAM_BASE:
+	 *
+	 * Data access violation, mfar = <CONFIG_RAM_BASE>
+	 */
+	data = ram_base[0];
+
+	return EC_SUCCESS;
+}
+
+test_static int test_mpu_update_region_invalid_region(void)
+{
+	/* Test invalid region */
+	TEST_EQ(mpu_update_region(mpu_info.num_mpu_regions, 0x8020000, 17,
+				  0x1000, 1, 0),
+		-EC_ERROR_INVAL, "%d");
+	return EC_SUCCESS;
+}
+
+test_static int test_mpu_update_region_invalid_alignment(void)
+{
+	/*
+	 * Test size that is not aligned to address.
+	 */
+	const uint32_t addr = 0x20000;
+	const uint32_t size = 0x40000;
+	const uint32_t size_bit = 18;
+
+	TEST_EQ(size, BIT(size_bit), "%d");
+	TEST_EQ(reset_mpu(), EC_SUCCESS, "%d");
+	TEST_EQ(mpu_update_region(0, addr, size_bit, 0, 1, 0), -EC_ERROR_INVAL,
+		"%d");
+
+	return EC_SUCCESS;
+}
+
+void run_test(void)
+{
+	ccprintf("Running MPU test\n");
+	RUN_TEST(reset_mpu);
+	RUN_TEST(test_mpu_info);
+	RUN_TEST(reset_mpu);
+	RUN_TEST(test_mpu_update_region_invalid_region);
+	RUN_TEST(reset_mpu);
+	RUN_TEST(test_mpu_update_region_invalid_alignment);
+	RUN_TEST(reset_mpu);
+	RUN_TEST(test_mpu_update_region_valid_region);
+	RUN_TEST(reset_mpu);
+	test_print_result();
+}

test/mpu.tasklist

@@ -0,0 +1,9 @@
+/* Copyright 2020 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+/**
+ * See CONFIG_TASK_LIST in config.h for details.
+ */
+#define CONFIG_TEST_TASK_LIST  /* no tasks */