Revert the MPU hack by splitting the store in 2

boards/nordic/nrf52840_dongle_opensk/src/main.rs

@@ -64,11 +64,19 @@ const NUM_PROCS: usize = 8;
 static mut PROCESSES: [Option<&'static dyn kernel::procs::ProcessType>; NUM_PROCS] =
     [None; NUM_PROCS];
 
-static mut STORAGE_LOCATIONS: [kernel::StorageLocation; 1] = [kernel::StorageLocation {
+static mut STORAGE_LOCATIONS: [kernel::StorageLocation; 2] = [
-    address: 0xC0000,
+    // We implement NUM_PAGES = 20 as 16 + 4 to satisfy the MPU.
-    size: 0x14000, // NUM_PAGES = 20
+    kernel::StorageLocation {
-    storage_type: kernel::StorageType::STORE,
+        address: 0xC0000,
-}];
+        size: 0x10000, // 16 pages
+        storage_type: kernel::StorageType::STORE,
+    },
+    kernel::StorageLocation {
+        address: 0xD0000,
+        size: 0x4000, // 4 pages
+        storage_type: kernel::StorageType::STORE,
+    },
+];
 
 // Static reference to chip for panic dumps
 static mut CHIP: Option<&'static nrf52840::chip::NRF52<Nrf52840DefaultPeripherals>> = None;

boards/nordic/nrf52840_mdk_dfu/src/main.rs

@@ -58,11 +58,19 @@ const NUM_PROCS: usize = 8;
 static mut PROCESSES: [Option<&'static dyn kernel::procs::ProcessType>; NUM_PROCS] =
     [None; NUM_PROCS];
 
-static mut STORAGE_LOCATIONS: [kernel::StorageLocation; 1] = [kernel::StorageLocation {
+static mut STORAGE_LOCATIONS: [kernel::StorageLocation; 2] = [
-    address: 0xC0000,
+    // We implement NUM_PAGES = 20 as 16 + 4 to satisfy the MPU.
-    size: 0x14000, // NUM_PAGES = 20
+    kernel::StorageLocation {
-    storage_type: kernel::StorageType::STORE,
+        address: 0xC0000,
-}];
+        size: 0x10000, // 16 pages
+        storage_type: kernel::StorageType::STORE,
+    },
+    kernel::StorageLocation {
+        address: 0xD0000,
+        size: 0x4000, // 4 pages
+        storage_type: kernel::StorageType::STORE,
+    },
+];
 
 // Static reference to chip for panic dumps
 static mut CHIP: Option<&'static nrf52840::chip::NRF52<Nrf52840DefaultPeripherals>> = None;

boards/nordic/nrf52840dk_opensk/src/main.rs

@@ -128,11 +128,19 @@ const NUM_PROCS: usize = 8;
 static mut PROCESSES: [Option<&'static dyn kernel::procs::ProcessType>; NUM_PROCS] =
     [None; NUM_PROCS];
 
-static mut STORAGE_LOCATIONS: [kernel::StorageLocation; 1] = [kernel::StorageLocation {
+static mut STORAGE_LOCATIONS: [kernel::StorageLocation; 2] = [
-    address: 0xC0000,
+    // We implement NUM_PAGES = 20 as 16 + 4 to satisfy the MPU.
-    size: 0x14000, // NUM_PAGES = 20
+    kernel::StorageLocation {
-    storage_type: kernel::StorageType::STORE,
+        address: 0xC0000,
-}];
+        size: 0x10000, // 16 pages
+        storage_type: kernel::StorageType::STORE,
+    },
+    kernel::StorageLocation {
+        address: 0xD0000,
+        size: 0x4000, // 4 pages
+        storage_type: kernel::StorageType::STORE,
+    },
+];
 
 static mut CHIP: Option<&'static nrf52840::chip::NRF52<Nrf52840DefaultPeripherals>> = None;
 

patches/tock/01-persistent-storage.patch

@@ -349,7 +349,7 @@ index 348c746a5..5465c95f4 100644
      }
  }
 diff --git a/kernel/src/process.rs b/kernel/src/process.rs
-index c52754be3..f5c833ea7 100644
+index c52754be3..ae6a58341 100644
 --- a/kernel/src/process.rs
 +++ b/kernel/src/process.rs
 @@ -359,6 +359,15 @@ pub trait ProcessType {
@@ -404,37 +404,33 @@ index c52754be3..f5c833ea7 100644
      fn update_stack_start_pointer(&self, stack_pointer: *const u8) {
          if stack_pointer >= self.mem_start() && stack_pointer < self.mem_end() {
              self.debug.map(|debug| {
-@@ -1751,6 +1789,37 @@ impl<C: 'static + Chip> Process<'_, C> {
+@@ -1751,6 +1789,33 @@ impl<C: 'static + Chip> Process<'_, C> {
              return Err(ProcessLoadError::MpuInvalidFlashLength);
          }
  
 +        // Allocate MPU region for the storage locations. The storage locations are currently
 +        // readable by all processes due to lack of stable app id.
-+        'storage_location: for storage_location in kernel.storage_locations() {
++        for storage_location in kernel.storage_locations() {
-+            // We work around MPU limitations on Nordic by also trying unallocated_size = 0x40000.
++            if chip
-+            // Note that just using the next power of 2 doesn't work.
++                .mpu()
-+            for &unallocated_size in &[storage_location.size, 0x40000] {
++                .allocate_region(
-+                if chip
++                    storage_location.address as *const u8,
-+                    .mpu()
++                    storage_location.size,
-+                    .allocate_region(
++                    storage_location.size,
-+                        storage_location.address as *const u8,
++                    mpu::Permissions::ReadOnly,
-+                        unallocated_size,
++                    &mut mpu_config,
-+                        storage_location.size,
++                )
-+                        mpu::Permissions::ReadOnly,
++                .is_some()
-+                        &mut mpu_config,
++            {
-+                    )
++                continue;
-+                    .is_some()
++            }
-+                {
++            if config::CONFIG.debug_load_processes {
-+                    continue 'storage_location;
++                debug!(
-+                }
++                    "[!] flash=[{:#010X}:{:#010X}] process={:?} - couldn't allocate flash region",
-+                if config::CONFIG.debug_load_processes {
++                    storage_location.address,
-+                    debug!(
++                    storage_location.address + storage_location.size,
-+                        "[!] flash=[{:#010X}:{:#010X}] process={:?} - couldn't allocate flash region",
++                    process_name
-+                        storage_location.address,
++                );
-+                        storage_location.address + unallocated_size,
-+                        process_name
-+                    );
-+                }
 +            }
 +            return Ok((None, remaining_memory));
 +        }