[nrf noup] loader: introduced cleanup of unusable secondary slot

Added procedure which clean-up content of all the secondary slot
which contains valid header but couldn't be assigned to any of
supported primary images.
This behavior is needed when configuration allows to use one secondary
slot for collecting image for multiple primary slots.

Signed-off-by: Andrzej Puzdrowski <[email protected]>
(cherry picked from commit 8f4b472)

Author: nvlsianpu

boot/bootutil/src/loader.c

@@ -1240,6 +1240,87 @@ boot_update_security_counter(uint8_t image_index, int slot,
 }
 #endif /* MCUBOOT_HW_ROLLBACK_PROT */
 
+#if defined(CONFIG_MCUBOOT_CLEANUP_UNUSABLE_SECONDARY) &&\
+(defined(PM_S1_ADDRESS) || defined(CONFIG_SOC_NRF5340_CPUAPP))
+
+#define SEC_SLOT_VIRGIN 0
+#define SEC_SLOT_TOUCHED 1
+#define SEC_SLOT_ASSIGNED 2
+
+#if (MCUBOOT_IMAGE_NUMBER == 2) && defined(PM_B0_ADDRESS) && \
+      !defined(CONFIG_NRF53_MULTI_IMAGE_UPDATE)
+/* This configuration is peculiar - the one physical secondary slot is
+ * mocking two logical secondary
+ */
+#define SEC_SLOT_PHYSICAL_CNT 1
+#else
+#define SEC_SLOT_PHYSICAL_CNT MCUBOOT_IMAGE_NUMBER
+#endif
+
+static uint8_t sec_slot_assignmnet[SEC_SLOT_PHYSICAL_CNT] = {0};
+
+static inline void sec_slot_touch(struct boot_loader_state *state)
+{
+    uint8_t idx = (SEC_SLOT_PHYSICAL_CNT == 1) ? 0 : BOOT_CURR_IMG(state);
+
+    if (SEC_SLOT_VIRGIN == sec_slot_assignmnet[idx]) {
+        sec_slot_assignmnet[idx] = SEC_SLOT_TOUCHED;
+    }
+}
+
+static inline void sec_slot_mark_assigned(struct boot_loader_state *state)
+{
+    uint8_t idx = (SEC_SLOT_PHYSICAL_CNT == 1) ? 0 : BOOT_CURR_IMG(state);
+
+    sec_slot_assignmnet[idx] = SEC_SLOT_ASSIGNED;
+}
+
+/**
+ * Cleanu up all secondary slot which couldn't be assigned to any primary slot.
+ *
+ * This function erases content of each secondary slot which contains valid
+ * header but couldn't be assigned to any of supported primary images.
+ *
+ * This function is supposed to be called after boot_validated_swap_type()
+ * iterates over all the images in context_boot_go().
+ */
+static void sec_slot_cleanup_if_unusable(void)
+{
+    uint8_t idx;
+
+    for (idx = 0; idx < SEC_SLOT_PHYSICAL_CNT; idx++) {
+        if (SEC_SLOT_TOUCHED == sec_slot_assignmnet[idx]) {
+            const struct flash_area *secondary_fa;
+            int rc;
+
+            rc = flash_area_open(flash_area_id_from_multi_image_slot(idx, BOOT_SECONDARY_SLOT),
+                                 &secondary_fa);
+            if (!rc) {
+                rc = flash_area_erase(secondary_fa, 0, secondary_fa->fa_size);
+                if (!rc) {
+                    BOOT_LOG_ERR("Cleaned-up secondary slot of %d. image.", idx);
+                }
+            }
+
+            if (rc) {
+                BOOT_LOG_ERR("Can not cleanup secondary slot of %d. image.", idx);
+            }
+        }
+    }
+}
+#else
+static inline void sec_slot_touch(struct boot_loader_state *state)
+{
+}
+static inline void sec_slot_mark_assigned(struct boot_loader_state *state)
+{
+}
+static inline void sec_slot_cleanup_if_unusable(void)
+{
+}
+#endif /* defined(CONFIG_MCUBOOT_CLEANUP_UNUSABLE_SECONDARY) &&\
+          defined(PM_S1_ADDRESS) || defined(CONFIG_SOC_NRF5340_CPUAPP) */
+
 #if !defined(MCUBOOT_DIRECT_XIP) && !defined(MCUBOOT_RAM_LOAD)
 /**
  * Determines which swap operation to perform, if any.  If it is determined
@@ -1278,6 +1359,9 @@ boot_validated_swap_type(struct boot_loader_state *state,
         if (rc != 0) {
             return BOOT_SWAP_TYPE_FAIL;
         }
+
+        sec_slot_touch(state);
+
 #ifdef PM_S1_ADDRESS
 #ifdef PM_CPUNET_B0N_ADDRESS
         if(reset_addr < PM_CPUNET_B0N_ADDRESS)
@@ -1312,6 +1396,7 @@ boot_validated_swap_type(struct boot_loader_state *state,
                     }
 #else
                 return BOOT_SWAP_TYPE_NONE;
+
 #endif
 
             } else if (reset_addr > (primary_fa->fa_off + primary_fa->fa_size)) {
@@ -1320,7 +1405,9 @@ boot_validated_swap_type(struct boot_loader_state *state,
             }
         }
 #endif /* PM_S1_ADDRESS */
+        sec_slot_mark_assigned(state);
     }
+
 #endif /* PM_S1_ADDRESS || CONFIG_SOC_NRF5340_CPUAPP */
 
     swap_type = boot_swap_type_multi(BOOT_CURR_IMG(state));
@@ -2450,6 +2537,9 @@ context_boot_go(struct boot_loader_state *state, struct boot_rsp *rsp)
         }
     }
 
+    /* cleanup secondary slots which were recognized unusable*/
+    sec_slot_cleanup_if_unusable();
+
 #if (BOOT_IMAGE_NUMBER > 1)
     if (has_upgrade) {
         /* Iterate over all the images and verify whether the image dependencies