bootutil: fix scratch status offset calculation
Update `boot_status_off` to take into consideration that scratch only
has to store status for one swap of sectors, thus requiring much less
flash space than what is required in the primary slot.
This commits does a bit of refactoring on the functions that return
parts of trailer size to make the code clearer.
Signed-off-by: Fabio Utzig <utzig@apache.org>
diff --git a/boot/bootutil/src/bootutil_misc.c b/boot/bootutil/src/bootutil_misc.c
index 0819257..4ae27b2 100644
--- a/boot/bootutil/src/bootutil_misc.c
+++ b/boot/bootutil/src/bootutil_misc.c
@@ -94,18 +94,15 @@
}
#endif
-uint32_t
-boot_status_sz(uint32_t min_write_sz)
+/*
+ * Amount of space used to save information required when doing a swap,
+ * or while a swap is under progress, but not the status of sector swap
+ * progress itself.
+ */
+static inline uint32_t
+boot_trailer_info_sz(void)
{
- return /* state for all sectors */
- BOOT_STATUS_MAX_ENTRIES * BOOT_STATUS_STATE_COUNT * min_write_sz;
-}
-
-uint32_t
-boot_trailer_sz(uint32_t min_write_sz)
-{
- return /* state for all sectors */
- boot_status_sz(min_write_sz) +
+ return (
#ifdef MCUBOOT_ENC_IMAGES
/* encryption keys */
# if MCUBOOT_SWAP_SAVE_ENCTLV
@@ -116,9 +113,46 @@
#endif
/* swap_type + copy_done + image_ok + swap_size */
BOOT_MAX_ALIGN * 4 +
- BOOT_MAGIC_SZ;
+ BOOT_MAGIC_SZ
+ );
}
+/*
+ * Amount of space used to maintain progress information for a single swap
+ * operation.
+ */
+static inline uint32_t
+boot_status_entry_sz(uint32_t min_write_sz)
+{
+ return BOOT_STATUS_STATE_COUNT * min_write_sz;
+}
+
+uint32_t
+boot_status_sz(uint32_t min_write_sz)
+{
+ return BOOT_STATUS_MAX_ENTRIES * boot_status_entry_sz(min_write_sz);
+}
+
+uint32_t
+boot_trailer_sz(uint32_t min_write_sz)
+{
+ return boot_status_sz(min_write_sz) + boot_trailer_info_sz();
+}
+
+#if MCUBOOT_SWAP_USING_SCRATCH
+/*
+ * Similar to `boot_trailer_sz` but this function returns the space used to
+ * store status in the scratch partition. The scratch partition only stores
+ * status during the swap of the last sector from primary/secondary (which
+ * is the first swap operation) and thus only requires space for one swap.
+ */
+static uint32_t
+boot_scratch_trailer_sz(uint32_t min_write_sz)
+{
+ return boot_status_entry_sz(min_write_sz) + boot_trailer_info_sz();
+}
+#endif
+
int
boot_status_entries(int image_index, const struct flash_area *fap)
{
@@ -142,7 +176,15 @@
elem_sz = flash_area_align(fap);
- off_from_end = boot_trailer_sz(elem_sz);
+#if MCUBOOT_SWAP_USING_SCRATCH
+ if (fap->fa_id == FLASH_AREA_IMAGE_SCRATCH) {
+ off_from_end = boot_scratch_trailer_sz(elem_sz);
+ } else {
+#endif
+ off_from_end = boot_trailer_sz(elem_sz);
+#if MCUBOOT_SWAP_USING_SCRATCH
+ }
+#endif
assert(off_from_end <= flash_area_get_size(fap));
return flash_area_get_size(fap) - off_from_end;