MPU support for PT2/PR2

src/fw/drivers/mpu.c

@@ -124,7 +124,11 @@ void mpu_enable(void) {
                      s_cache_settings[MpuCachePolicy_WriteBackNoWriteAllocate]);
 #endif
 
+#ifdef MICRO_FAMILY_SF32LB52
+  ARM_MPU_Enable(MPU_CTRL_PRIVDEFENA_Msk | MPU_CTRL_HFNMIENA_Msk);
+#else
   ARM_MPU_Enable(MPU_CTRL_PRIVDEFENA_Msk);
+#endif
 }
 
 void mpu_disable(void) {
@@ -269,18 +273,16 @@ void mpu_set_task_configurable_regions(MemoryRegion_t *memory_regions,
     // If not region defined, use unused
     if (mpu_region == NULL) {
       mpu_region = &unused_region;
+      base_reg = 0;
       attr_reg = 0; // Has a 0 in the enable bit, so this region won't be enabled.
     } else {
       // Make sure that the region numbers passed in jive with the configurable region numbers.
       PBL_ASSERTN(mpu_region->region_num == region_num);
-      // Our FreeRTOS port makes the assumption that the ulParameters field contains exactly what
-      // should be placed into the MPU_RASR register. It will figure out the MPU_RBAR from the
-      // pvBaseAddress field.
       mpu_get_register_settings(mpu_region, &base_reg, &attr_reg);
     }
 
     memory_regions[region_idx] = (MemoryRegion_t) {
-      .pvBaseAddress = (void *)mpu_region->base_address,
+      .pvBaseAddress = (void *)(uintptr_t)base_reg,
       .ulLengthInBytes = mpu_region->size,
       .ulParameters = attr_reg,
     };

src/fw/kernel/pebble_tasks.c

@@ -13,6 +13,7 @@
 #include "util/size.h"
 
 #include "FreeRTOS.h"
+#include "portmacro.h"
 #include "task.h"
 #include "queue.h"
 
@@ -197,14 +198,22 @@ void pebble_task_create(PebbleTask pebble_task, TaskParameters_t *task_params,
       WTF;
   }
 
+  app_region.region_num = portFIRST_CONFIGURABLE_REGION;
+  worker_region.region_num = portFIRST_CONFIGURABLE_REGION + 1;
+
+  MpuRegion stack_guard_copy;
+  const MpuRegion *stack_guard_ptr = NULL;
+  if (stack_guard_region != NULL) {
+    stack_guard_copy = *stack_guard_region;
+    stack_guard_copy.region_num = portFIRST_CONFIGURABLE_REGION + 2;
+    stack_guard_ptr = &stack_guard_copy;
+  }
+
   const MpuRegion *region_ptrs[portNUM_CONFIGURABLE_REGIONS] = {
-    // FIXME(SF32LB52): Not supported on ARMv8 MPU yet
-#ifndef MICRO_FAMILY_SF32LB52
     &app_region,
     &worker_region,
-    stack_guard_region,
+    stack_guard_ptr,
     NULL
-#endif
   };
   mpu_set_task_configurable_regions(task_params->xRegions, region_ptrs);
 
@@ -232,6 +241,8 @@ void pebble_task_configure_idle_task(void) {
                               false /* allow_user_access */);
   mpu_init_region_from_region(&worker_region, memory_layout_get_worker_region(),
                               false /* allow_user_access */);
+  app_region.region_num = portFIRST_CONFIGURABLE_REGION;
+  worker_region.region_num = portFIRST_CONFIGURABLE_REGION + 1;
   const MpuRegion *region_ptrs[portNUM_CONFIGURABLE_REGIONS] = {
     &app_region,
     &worker_region,

src/fw/wscript

@@ -264,17 +264,13 @@ def _generate_memory_layout(bld):
         app_ram_size_3x = APP_RAM_SIZES['basalt']
         app_ram_size_4x = APP_RAM_SIZES['emery']
         # We have 512K of SRAM, last 1K reserved for LCPU IPC
-        # FIXME(SF32LB52): due to MPU find_subregions_for_region assuming
-        # ARMv7 subregion limitations, we need to reserve 32K!
-        total_ram = (0x20000000, (512 - 32) * 1024)
+        total_ram = (0x20000000, (512 - 1) * 1024)
     elif bld.is_getafix():
         app_ram_size_2x = APP_UNSUPPORTED
         app_ram_size_3x = APP_RAM_SIZES['chalk']
         app_ram_size_4x = APP_RAM_SIZES['gabbro']
         # We have 512K of SRAM, last 1K reserved for LCPU IPC
-        # FIXME(SF32LB52): due to MPU find_subregions_for_region assuming
-        # ARMv7 subregion limitations, we need to reserve 32K!
-        total_ram = (0x20000000, (512 - 32) * 1024)
+        total_ram = (0x20000000, (512 - 1) * 1024)
     else:
         bld.fatal("No set of supported SDK platforms defined for this board")
 
@@ -320,18 +316,26 @@ def _generate_memory_layout(bld):
         FLASH_SIZE=flash_size,
         BOOTLOADER_SYMBOLS=bootloader_symbol_definitions)
 
-    app_mpu_region = tools.mpu_calc.find_subregions_for_region(app_ram[0], app_ram[1])
-    worker_mpu_region = tools.mpu_calc.find_subregions_for_region(worker_ram[0], worker_ram[1])
+    if bld.env.MICRO_FAMILY == 'SF32LB52':
+        app_mpu_region = tools.mpu_calc.find_region_for_armv8(app_ram[0], app_ram[1])
+        worker_mpu_region = tools.mpu_calc.find_region_for_armv8(worker_ram[0], worker_ram[1])
+        app_disabled_sub = "0"
+        worker_disabled_sub = "0"
+    else:
+        app_mpu_region = tools.mpu_calc.find_subregions_for_region(app_ram[0], app_ram[1])
+        worker_mpu_region = tools.mpu_calc.find_subregions_for_region(worker_ram[0], worker_ram[1])
+        app_disabled_sub = "0b{:08b}".format(app_mpu_region.disabled_subregion)
+        worker_disabled_sub = " 0b{:08b}".format(worker_mpu_region.disabled_subregion)
 
     bld(features='subst',
         source=bld.path.find_node('kernel/mpu_regions.template.h'),
         target=bld.path.get_bld().make_node('kernel/mpu_regions.auto.h'),
         APP_BASE_ADDRESS="0x{:x}".format(app_mpu_region.address),
         APP_SIZE="0x{:x}".format(app_mpu_region.size),
-        APP_DISABLED_SUBREGIONS="0b{:08b}".format(app_mpu_region.disabled_subregion),
+        APP_DISABLED_SUBREGIONS=app_disabled_sub,
         WORKER_BASE_ADDRESS="0x{:x}".format(worker_mpu_region.address),
         WORKER_SIZE="0x{:x}".format(worker_mpu_region.size),
-        WORKER_DISABLED_SUBREGIONS=" 0b{:08b}".format(worker_mpu_region.disabled_subregion))
+        WORKER_DISABLED_SUBREGIONS=worker_disabled_sub)
 
     bld(features='subst',
         source=bld.path.find_node('process_management/sdk_memory_limits.template.h'),

third_party/freertos/wscript

@@ -26,11 +26,9 @@ def build(bld):
                            for d in freertos_source_paths], [])
     freertos_defines = []
 
-    # FIXME(SF32LB52): Add valid regions once MPU can be used
-    # This currently results in 0 regions!
     if bld.env.MICRO_FAMILY == 'SF32LB52':
         freertos_defines += [
-            'FREERTOS_FIRST_MPU_REGION=8',
+            'FREERTOS_FIRST_MPU_REGION=4',
             'FREERTOS_LAST_MPU_REGION=7',
         ]
 

tools/mpu_calc.py

@@ -91,6 +91,21 @@ def find_subregions_for_region(address, size):
         raise Exception("No solution found")
 
 
+def find_region_for_armv8(address, size):
+    """Find MPU region for ARMv8-M (no subregions, arbitrary 32-byte-aligned size).
+
+    ARMv8-M MPU supports regions of any size aligned to 32 bytes.
+    Returns MpuRegion(address, size, 0) with disabled_subregion=0 (unused on ARMv8).
+    """
+    if address % 32 != 0:
+        raise Exception("Address must be 32-byte aligned for ARMv8-M MPU")
+    if size % 32 != 0:
+        raise Exception("Size must be 32-byte aligned for ARMv8-M MPU")
+    if size < MIN_REGION_SIZE:
+        raise Exception("Size must be at least 32 bytes")
+    return MpuRegion(address=address, size=size, disabled_subregion=0)
+
+
 if __name__ == "__main__":
     import doctest