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stm32/mboot: Make all mboot sectors erase/write protected.

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Prior to this commit, only sector 0 was erase/write protected, which may
not be enough to protect all of mboot (especially if mboot lives at a
higher address than the start of flash).

This commit makes sure all internal flash sectors that mboot lives in are
protected from erasing and writing.  The linker script must define
_mboot_writable_flash_start for this to work.

Signed-off-by: Damien George <damien@micropython.org>
This commit is contained in:
Damien George 2022-11-23 21:41:48 +11:00
parent 1b774b373e
commit 771c16f3d9
4 changed files with 26 additions and 5 deletions
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3
ports/stm32/boards/LEGO_HUB_NO6/mboot_memory.ld
View File

@ -8,3 +8,6 @@ MEMORY
RAM (xrw) : ORIGIN = 0x20000000, LENGTH = 120K
}
/* Location from which mboot is allowed to write to flash.
Must be the start of a flash erase sector. */
_mboot_writable_flash_start = ORIGIN(FLASH_BL) + LENGTH(FLASH_BL);

23
ports/stm32/mboot/main.c
View File

@ -108,9 +108,15 @@
// These bits are used to detect valid application firmware at APPLICATION_ADDR
#define APP_VALIDITY_BITS (0x00000003)
// Symbol provided by the linker, at the address in flash where mboot can start erasing/writing.
extern uint8_t _mboot_writable_flash_start;
// For 1ms system ticker.
volatile uint32_t systick_ms;
// The sector number of the first sector that can be erased/written.
int32_t first_writable_flash_sector;
// Global dfu state
dfu_context_t dfu_context SECTION_NOZERO_BSS;
@ -403,7 +409,6 @@ void mp_hal_pin_config_speed(uint32_t port_pin, uint32_t speed) {
#if defined(STM32WB)
#define FLASH_END FLASH_END_ADDR
#endif
#define APPLICATION_FLASH_LENGTH (FLASH_END + 1 - APPLICATION_ADDR)
#ifndef MBOOT_SPIFLASH_LAYOUT
#define MBOOT_SPIFLASH_LAYOUT ""
@ -431,7 +436,9 @@ void mp_hal_pin_config_speed(uint32_t port_pin, uint32_t speed) {
static int mboot_flash_mass_erase(void) {
// Erase all flash pages after mboot.
int ret = flash_erase(APPLICATION_ADDR, APPLICATION_FLASH_LENGTH / sizeof(uint32_t));
uint32_t start_addr = (uint32_t)&_mboot_writable_flash_start;
uint32_t num_words = (FLASH_END + 1 - start_addr) / sizeof(uint32_t);
int ret = flash_erase(start_addr, num_words);
return ret;
}
@ -439,7 +446,7 @@ static int mboot_flash_page_erase(uint32_t addr, uint32_t *next_addr) {
uint32_t sector_size = 0;
uint32_t sector_start = 0;
int32_t sector = flash_get_sector_info(addr, &sector_start, &sector_size);
if (sector <= 0) {
if (sector < first_writable_flash_sector) {
// Don't allow to erase the sector with this bootloader in it, or invalid sectors
dfu_context.status = DFU_STATUS_ERROR_ADDRESS;
dfu_context.error = (sector == 0) ? MBOOT_ERROR_STR_OVERWRITE_BOOTLOADER_IDX
@ -467,8 +474,8 @@ static int mboot_flash_page_erase(uint32_t addr, uint32_t *next_addr) {
static int mboot_flash_write(uint32_t addr, const uint8_t *src8, size_t len) {
int32_t sector = flash_get_sector_info(addr, NULL, NULL);
if (sector <= 0) {
// Don't allow to write the sector with this bootloader in it
if (sector < first_writable_flash_sector) {
// Don't allow to write the sector with this bootloader in it, or invalid sectors.
dfu_context.status = DFU_STATUS_ERROR_ADDRESS;
dfu_context.error = (sector == 0) ? MBOOT_ERROR_STR_OVERWRITE_BOOTLOADER_IDX
: MBOOT_ERROR_STR_INVALID_ADDRESS_IDX;
@ -1379,6 +1386,12 @@ enter_bootloader:
__ASM volatile ("msr basepri_max, %0" : : "r" (pri) : "memory");
#endif
// Compute the first erasable/writable internal flash sector.
first_writable_flash_sector = flash_get_sector_info((uint32_t)&_mboot_writable_flash_start, NULL, NULL);
if (first_writable_flash_sector < 0) {
first_writable_flash_sector = INT32_MAX;
}
#if defined(MBOOT_SPIFLASH_ADDR)
MBOOT_SPIFLASH_SPIFLASH->config = MBOOT_SPIFLASH_CONFIG;
mp_spiflash_init(MBOOT_SPIFLASH_SPIFLASH);

1
ports/stm32/mboot/mboot.h
View File

@ -169,6 +169,7 @@ typedef uint32_t mboot_addr_t;
extern volatile uint32_t systick_ms;
extern uint8_t _estack[ELEM_DATA_SIZE];
extern int32_t first_writable_flash_sector;
void systick_init(void);
void led_init(void);

4
ports/stm32/mboot/stm32_memory.ld
View File

@ -8,3 +8,7 @@ MEMORY
FLASH_BL (rx) : ORIGIN = 0x08000000, LENGTH = 32K
RAM (xrw) : ORIGIN = 0x20000000, LENGTH = 120K
}
/* Location from which mboot is allowed to write to flash.
Must be the start of a flash erase sector. */
_mboot_writable_flash_start = ORIGIN(FLASH_BL) + LENGTH(FLASH_BL);