OVMS3-idf/components/spi_flash/esp32/flash_ops_esp32.c
Mahavir Jain 56accfe4c4 spi_flash: esp32: fix regression in encrypted flash write
In commit 309376f51a, it seems like regression
was added to use ROM level API for disabling flash write protection. This
started random firmware crashes (on specific modules) with exception
`IllegalInstruction` during encrypted flash writes.

Fix here removes relevant ROM API call, since disabling flash write protection
is already ensured by caller of this API.

Closes https://github.com/espressif/esp-idf/issues/5467
2020-06-29 14:51:58 +05:30

86 lines
3.1 KiB
C

// Copyright 2018 Espressif Systems (Shanghai) PTE LTD
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include <string.h>
#include "esp_spi_flash.h"
#include "esp32/rom/spi_flash.h"
#include "esp32/rom/cache.h"
static inline void IRAM_ATTR spi_flash_guard_start(void)
{
const spi_flash_guard_funcs_t *ops = spi_flash_guard_get();
if (ops && ops->start) {
ops->start();
}
}
static inline void IRAM_ATTR spi_flash_guard_end(void)
{
const spi_flash_guard_funcs_t *ops = spi_flash_guard_get();
if (ops && ops->end) {
ops->end();
}
}
esp_rom_spiflash_result_t IRAM_ATTR spi_flash_write_encrypted_chip(size_t dest_addr, const void *src, size_t size)
{
const uint8_t *ssrc = (const uint8_t *)src;
esp_rom_spiflash_result_t rc = ESP_ROM_SPIFLASH_RESULT_OK;
assert((dest_addr % 16) == 0);
assert((size % 16) == 0);
/* esp_rom_spiflash_write_encrypted encrypts data in RAM as it writes,
so copy to a temporary buffer - 32 bytes at a time.
Each call to esp_rom_spiflash_write_encrypted takes a 32 byte "row" of
data to encrypt, and each row is two 16 byte AES blocks
that share a key (as derived from flash address).
*/
uint8_t encrypt_buf[32] __attribute__((aligned(4)));
uint32_t row_size;
for (size_t i = 0; i < size; i += row_size) {
uint32_t row_addr = dest_addr + i;
if (i == 0 && (row_addr % 32) != 0) {
/* writing to second block of a 32 byte row */
row_size = 16;
row_addr -= 16;
/* copy to second block in buffer */
memcpy(encrypt_buf + 16, ssrc + i, 16);
/* decrypt the first block from flash, will reencrypt to same bytes */
spi_flash_read_encrypted(row_addr, encrypt_buf, 16);
} else if (size - i == 16) {
/* 16 bytes left, is first block of a 32 byte row */
row_size = 16;
/* copy to first block in buffer */
memcpy(encrypt_buf, ssrc + i, 16);
/* decrypt the second block from flash, will reencrypt to same bytes */
spi_flash_read_encrypted(row_addr + 16, encrypt_buf + 16, 16);
} else {
/* Writing a full 32 byte row (2 blocks) */
row_size = 32;
memcpy(encrypt_buf, ssrc + i, 32);
}
spi_flash_guard_start();
rc = esp_rom_spiflash_write_encrypted(row_addr, (uint32_t *)encrypt_buf, 32);
spi_flash_guard_end();
if (rc != ESP_ROM_SPIFLASH_RESULT_OK) {
break;
}
}
bzero(encrypt_buf, sizeof(encrypt_buf));
return rc;
}