From 4fceb73db9308ba40888e378d18951a9537b1db3 Mon Sep 17 00:00:00 2001
From: Marcos Chaparro <mchaparro@powerdesigns.ca>
Date: Wed, 17 Apr 2019 20:54:08 -0300
Subject: [PATCH] Continuous flash memory integrity check running on background

Create a new, low priority thread that checks that the CRC of the
flash memory matches the CRC stored in flash.

8kB chunks are computed every 50 milliseconds. A reset is invoked if
CRC does not match.

Signed-off-by: Marcos Chaparro <mchaparro@powerdesigns.ca>
---
 flash_helper.c | 37 +++++++++++++++++++++++++++++++++----
 flash_helper.h |  1 +
 main.c         | 17 +++++++++++++++++
 3 files changed, 51 insertions(+), 4 deletions(-)

diff --git a/flash_helper.c b/flash_helper.c
index a60f6792..5ddfbfe1 100644
--- a/flash_helper.c
+++ b/flash_helper.c
@@ -56,11 +56,11 @@
 #define	APP_CRC_WAS_CALCULATED_FLAG			((uint32_t)0xAAAAAAAA)
 #define	APP_CRC_WAS_CALCULATED_FLAG_ADDRESS	(uint32_t*)(APP_MAX_SIZE - 8)
 
-#define VECTOR_TABLE_ADDRESS	(uint32_t *)ADDR_FLASH_SECTOR_0
-#define VECTOR_TABLE_SIZE		(ADDR_FLASH_SECTOR_1 - ADDR_FLASH_SECTOR_0)
+#define VECTOR_TABLE_ADDRESS	((uint32_t *)ADDR_FLASH_SECTOR_0)
+#define VECTOR_TABLE_SIZE		((uint32_t)(ADDR_FLASH_SECTOR_1 - ADDR_FLASH_SECTOR_0))
 
-#define APP_START_ADDRESS		(uint32_t *)(ADDR_FLASH_SECTOR_1 + EEPROM_EMULATION_SIZE)
-#define APP_SIZE				(APP_MAX_SIZE - VECTOR_TABLE_SIZE - EEPROM_EMULATION_SIZE)
+#define APP_START_ADDRESS		((uint32_t *)(ADDR_FLASH_SECTOR_1 + EEPROM_EMULATION_SIZE))
+#define APP_SIZE				((uint32_t)(APP_MAX_SIZE - VECTOR_TABLE_SIZE - EEPROM_EMULATION_SIZE))
 
 // Private constants
 static const uint32_t flash_addr[FLASH_SECTORS] = {
@@ -274,3 +274,32 @@ uint32_t flash_helper_verify_flash_memory(void) {
 		return FAULT_CODE_NONE;
 	}
 }
+
+uint32_t flash_helper_verify_flash_memory_chunk(void) {
+	static uint32_t index = 0;
+	const uint32_t chunk_size = 8192;
+	uint32_t res = FAULT_CODE_NONE;
+	uint32_t crc = 0;
+
+	// Make sure RCC_AHB1Periph_CRC is enabled
+	if (index == 0) {
+		crc32_reset();
+	}
+
+	if (index < VECTOR_TABLE_SIZE) {
+		crc32((VECTOR_TABLE_ADDRESS + index), chunk_size/4);
+	}
+	else {
+		crc = crc32((uint32_t*)((uint32_t)APP_START_ADDRESS + index - VECTOR_TABLE_SIZE), chunk_size/4);
+	}
+
+	index += chunk_size;
+	if (index >= (VECTOR_TABLE_SIZE + APP_SIZE)) {
+		index = 0;
+		if (crc != 0) {
+			res = FAULT_CODE_FLASH_CORRUPTION;
+		}
+	}
+	return res;
+}
+
diff --git a/flash_helper.h b/flash_helper.h
index 085078b7..053f1231 100644
--- a/flash_helper.h
+++ b/flash_helper.h
@@ -28,5 +28,6 @@ uint16_t flash_helper_write_new_app_data(uint32_t offset, uint8_t *data, uint32_
 void flash_helper_jump_to_bootloader(void);
 uint8_t* flash_helper_get_sector_address(uint32_t fsector);
 uint32_t flash_helper_verify_flash_memory(void);
+uint32_t flash_helper_verify_flash_memory_chunk(void);
 
 #endif /* FLASH_HELPER_H_ */
diff --git a/main.c b/main.c
index a8fd8e5d..f96d2f30 100644
--- a/main.c
+++ b/main.c
@@ -75,6 +75,22 @@
 // Private variables
 static THD_WORKING_AREA(periodic_thread_wa, 1024);
 static THD_WORKING_AREA(timer_thread_wa, 128);
+static THD_WORKING_AREA(flash_integrity_check_thread_wa, 1024);
+
+static THD_FUNCTION(flash_integrity_check_thread, arg) {
+	(void)arg;
+
+	chRegSetThreadName("Flash integrity check");
+	RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_CRC, ENABLE);
+
+	for(;;) {
+		if (flash_helper_verify_flash_memory_chunk() == FAULT_CODE_FLASH_CORRUPTION) {
+			NVIC_SystemReset();
+		}
+
+		chThdSleepMilliseconds(50);
+	}
+}
 
 static THD_FUNCTION(periodic_thread, arg) {
 	(void)arg;
@@ -245,6 +261,7 @@ int main(void) {
 	// Threads
 	chThdCreateStatic(periodic_thread_wa, sizeof(periodic_thread_wa), NORMALPRIO, periodic_thread, NULL);
 	chThdCreateStatic(timer_thread_wa, sizeof(timer_thread_wa), NORMALPRIO, timer_thread, NULL);
+	chThdCreateStatic(flash_integrity_check_thread_wa, sizeof(flash_integrity_check_thread_wa), LOWPRIO, flash_integrity_check_thread, NULL);
 
 #if WS2811_TEST
 	unsigned int color_ind = 0;