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bootloader: Calculate SHA256 hash of image on every boot

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Makes app image booting more reliable (256-bit rather than 8-bit verification.)

Some measurements, time to boot a 655KB app.bin file and run to app_main() execution.

(All for rev 1 silicon, ie no 340ms spurious WDT delay.)

80MHz QIO mode:
before = 300ms
after = 140ms

40MHz DIO mode:
before = 712ms
after = 577ms

40MHz DIO mode, secure boot enabled
before = 1380ms
after = 934ms

(Secure boot involves two ECC signature verifications (partition table, app) that take approx 300ms each with 80MHz CPU.)
This commit is contained in:
Angus Gratton
2017-06-28 16:46:34 +10:00
committed by Angus Gratton
parent caaa29c676
commit 17adb40ca8
12 changed files with 290 additions and 137 deletions
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46
components/bootloader_support/include/esp_image_format.h
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@@ -59,12 +59,27 @@ typedef enum {
typedef struct {
uint8_t magic;
uint8_t segment_count;
uint8_t spi_mode; /* flash read mode (esp_image_spi_mode_t as uint8_t) */
uint8_t spi_speed: 4; /* flash frequency (esp_image_spi_freq_t as uint8_t) */
uint8_t spi_size: 4; /* flash chip size (esp_image_flash_size_t as uint8_t) */
/* flash read mode (esp_image_spi_mode_t as uint8_t) */
uint8_t spi_mode;
/* flash frequency (esp_image_spi_freq_t as uint8_t) */
uint8_t spi_speed: 4;
/* flash chip size (esp_image_flash_size_t as uint8_t) */
uint8_t spi_size: 4;
uint32_t entry_addr;
uint8_t extra_header[16]; /* ESP32 additional header, unused by second bootloader */
} esp_image_header_t;
/* WP pin when SPI pins set via efuse (read by ROM bootloader, the IDF bootloader uses software to configure the WP
* pin and sets this field to 0xEE=disabled) */
uint8_t wp_pin;
/* Drive settings for the SPI flash pins (read by ROM bootloader) */
uint8_t spi_pin_drv[3];
/* Reserved bytes in ESP32 additional header space, currently unused */
uint8_t reserved[11];
/* If 1, a SHA256 digest "simple hash" (of the entire image) is appended after the checksum. Included in image length. This digest
* is separate to secure boot and only used for detecting corruption. For secure boot signed images, the signature
* is appended after this (and the simple hash is included in the signed data). */
uint8_t hash_appended;
} __attribute__((packed)) esp_image_header_t;
_Static_assert(sizeof(esp_image_header_t) == 24, "binary image header should be 24 bytes");
/* Header of binary image segment */
typedef struct {
@@ -97,18 +112,23 @@ typedef enum {
*
* If encryption is enabled, data will be transparently decrypted.
*
* @param mode Mode of operation (verify, silent verify, or load).
* @param part Partition to load the app from.
* @param[out] data Pointer to the metadata structure to be filled in by this function. 'start_addr' member should be set (to the start address of the image.) Other fields will all be initialised by this function.
* @param log_errors Log errors reading the image.
* @param[inout] data Pointer to the image metadata structure which is be filled in by this function. 'start_addr' member should be set (to the start address of the image.) Other fields will all be initialised by this function.
*
* Image validation checks:
* - Magic byte
* - Partition smaller than 16MB
* - All segments & image fit in partition
* - 8 bit image checksum is valid
* - (Signature) if signature verification is enabled
* - Magic byte.
* - Partition smaller than 16MB.
* - All segments & image fit in partition.
* - 8 bit image checksum is valid.
* - SHA-256 of image is valid (if image has this appended).
* - (Signature) if signature verification is enabled.
*
* @return ESP_OK if image metadata was loaded successfully, ESP_ERR_IMAGE_FLASH_FAIL if a SPI flash error occurs, ESP_ERR_IMAGE_INVALID if the image appears invalid, ESP_ERR_INVALID_ARG if the data pointer is invalid.
* @return
* - ESP_OK if verify or load was successful
* - ESP_ERR_IMAGE_FLASH_FAIL if a SPI flash error occurs
* - ESP_ERR_IMAGE_INVALID if the image appears invalid.
* - ESP_ERR_INVALID_ARG if the partition or data pointers are invalid.
*/
esp_err_t esp_image_load(esp_image_load_mode_t mode, const esp_partition_pos_t *part, esp_image_metadata_t *data);