diff --git a/exosphere/coldboot_main.c b/exosphere/coldboot_main.c
index f9f0acb8e..bb76ce8dc 100644
--- a/exosphere/coldboot_main.c
+++ b/exosphere/coldboot_main.c
@@ -1,3 +1,4 @@
+#include <string.h>
 #include "utils.h"
 #include "mmu.h"
 #include "memory_map.h"
@@ -6,6 +7,8 @@ extern void (*__fini_array_start[])(void);
 extern void (*__fini_array_end[])(void);
 extern void _fini(void);
 
+extern uint8_t __pk2ldr_start__[], __pk2ldr_end__[];
+
 extern void __jump_to_lower_el(uint64_t arg, uintptr_t ep, unsigned int el);
 
 void coldboot_main(void);
@@ -18,5 +21,13 @@ static void __libc_fini_array(void) __attribute__((used)) {
 }
 
 void coldboot_main(void) {
-    /* TODO */
+    uintptr_t *mmu_l3_table = (uintptr_t *)tzram_get_segment_address(TZRAM_SEGMENT_ID_L3_TRANSLATION_TABLE);
+    void *pk2ldr = (void *)tzram_get_segment_address(TZRAM_SEGMENT_ID_PK2LDR); 
+
+    /* Clear and unmap pk2ldr (which is reused as exception entry stacks) */
+    memset(pk2ldr, 0, __pk2ldr_end__ - __pk2ldr_start__);
+    mmu_unmap_range(mmu_l3_table, pk2ldr, __pk2ldr_end__ - __pk2ldr_start__);
+    tlb_invalidate_all_inner_shareable();
+
+    /* TODO: stuff & jump to lower EL */
 }
diff --git a/exosphere/mmu.h b/exosphere/mmu.h
index babcdfe91..f41da88f3 100644
--- a/exosphere/mmu.h
+++ b/exosphere/mmu.h
@@ -150,21 +150,21 @@ static inline void mmu_unmap(unsigned int level, uintptr_t *tbl, uintptr_t base_
 }
 
 static inline void mmu_map_block_range(unsigned int level, uintptr_t *tbl, uintptr_t base_addr, uintptr_t phys_addr, size_t size, uint64_t attrs) {
-    size = (size >> MMU_Lx_SHIFT(level)) << MMU_Lx_SHIFT(level);
+    size = ((size + (BITL(MMU_Lx_SHIFT(level)) - 1)) >> MMU_Lx_SHIFT(level)) << MMU_Lx_SHIFT(level);
     for(size_t offset = 0; offset < size; offset += MMU_Lx_SHIFT(level)) {
         mmu_map_block(level, tbl, base_addr + offset, phys_addr + offset, attrs);
     }
 }
 
 static inline void mmu_map_page_range(uintptr_t *tbl, uintptr_t base_addr, uintptr_t phys_addr, size_t size, uint64_t attrs) {
-    size = (size >> MMU_Lx_SHIFT(3)) << MMU_Lx_SHIFT(3);
+    size = ((size + (BITL(MMU_Lx_SHIFT(3)) - 1)) >> MMU_Lx_SHIFT(3)) << MMU_Lx_SHIFT(3);
     for(size_t offset = 0; offset < size; offset += MMU_Lx_SHIFT(3)) {
         mmu_map_page(tbl, base_addr + offset, phys_addr + offset, attrs);
     }
 }
 
 static inline void mmu_unmap_range(unsigned int level, uintptr_t *tbl, uintptr_t base_addr, size_t size) {
-    size = (size >> MMU_Lx_SHIFT(level)) << MMU_Lx_SHIFT(level);
+    size = ((size + (BITL(MMU_Lx_SHIFT(level)) - 1)) >> MMU_Lx_SHIFT(level)) << MMU_Lx_SHIFT(level);
     for(size_t offset = 0; offset < size; offset += MMU_Lx_SHIFT(level)) {
         mmu_unmap(level, tbl, base_addr + offset);
     }