fix(espcoredump): Ensure consistency between the flash and checksum data

This is a direct core dump of the current memory so it may change because
of other interrupt handlers or the memory used by the core dump process
itself. Always write the data via the cache buffer so that what's written
matches the checksum.

Fixes part of espressif/esp-zigbee-sdk#326 (invalid CRC when writing a core
dump to flash).

components/espcoredump/src/core_dump_flash.c

@@ -154,12 +154,10 @@ static esp_err_t esp_core_dump_flash_write_data(core_dump_write_data_t* wr_data,
     uint32_t wr_sz = 0;
 
     /* Make sure that the partition is large enough to hold the data. */
-    ESP_COREDUMP_ASSERT((wr_data->off + data_size) < s_core_flash_config.partition.size);
+    ESP_COREDUMP_ASSERT((wr_data->off + wr_data->cached_bytes + data_size) < s_core_flash_config.partition.size);
 
-    if (wr_data->cached_bytes) {
-        /* Some bytes are in the cache, let's continue filling the cache
-         * with the data received as parameter. Let's calculate the maximum
-         * amount of bytes we can still fill the cache with. */
+    while (data_size > 0) {
+        /* Calculate the maximum amount of bytes we can still fill the cache with. */
         if ((COREDUMP_CACHE_SIZE - wr_data->cached_bytes) > data_size) {
             wr_sz = data_size;
         } else {
@@ -167,7 +165,7 @@ static esp_err_t esp_core_dump_flash_write_data(core_dump_write_data_t* wr_data,
         }
 
         /* Append wr_sz bytes from data parameter to the cache. */
-        memcpy(&wr_data->cached_data[wr_data->cached_bytes], data, wr_sz);
+        memcpy(&wr_data->cached_data[wr_data->cached_bytes], data + written, wr_sz);
         wr_data->cached_bytes += wr_sz;
 
         if (wr_data->cached_bytes == COREDUMP_CACHE_SIZE) {
@@ -195,47 +193,6 @@ static esp_err_t esp_core_dump_flash_write_data(core_dump_write_data_t* wr_data,
         data_size -= wr_sz;
     }
 
-    /* Figure out how many bytes we can write onto the flash directly, without
-     * using the cache. In our case the cache size is a multiple of the flash's
-     * minimum writing block size, so we will use it for our calculation.
-     * For example, if COREDUMP_CACHE_SIZE equals 32, here are interesting
-     * values:
-     * +---------+-----------------------+
-     * |         |       data_size       |
-     * +---------+---+----+----+----+----+
-     * |         | 0 | 31 | 32 | 40 | 64 |
-     * +---------+---+----+----+----+----+
-     * | (blocks | 0 | 0  | 1  | 1  | 2) |
-     * +---------+---+----+----+----+----+
-     * | wr_sz   | 0 | 0  | 32 | 32 | 64 |
-     * +---------+---+----+----+----+----+
-     */
-    wr_sz = (data_size / COREDUMP_CACHE_SIZE) * COREDUMP_CACHE_SIZE;
-    if (wr_sz) {
-        /* Write the contiguous amount of bytes to the flash,
-         * without using the cache */
-        err = esp_core_dump_flash_custom_write(s_core_flash_config.partition.start + wr_data->off, data + written, wr_sz);
-
-        if (err != ESP_OK) {
-            ESP_COREDUMP_LOGE("Failed to write data to flash (%d)!", err);
-            return err;
-        }
-
-        /* Update the checksum with the newly written bytes */
-        esp_core_dump_checksum_update(&wr_data->checksum_ctx, data + written, wr_sz);
-        wr_data->off += wr_sz;
-        written += wr_sz;
-        data_size -= wr_sz;
-    }
-
-    if (data_size > 0) {
-        /* There still some bytes from the data parameter that need to be sent,
-         * append it to cache in order to write them later. (i.e. when there
-         * will be enough bytes to fill the cache) */
-        memcpy(&wr_data->cached_data, data + written, data_size);
-        wr_data->cached_bytes = data_size;
-    }
-
     return ESP_OK;
 }