physical_mm: Spinlock the memory bitmap

3 files changed, 16 insertions, 1 deletions

diff --git a/kernel/CMakeLists.txt b/kernel/CMakeLists.txt
index 7aa0889..059600d 100644
--- a/kernel/CMakeLists.txt
+++ b/kernel/CMakeLists.txt
@@ -41,6 +41,7 @@ set(C_COMPILE_OPTIONS
   -pedantic
   # -Werror
 
+  # TODO: This doesn't actually work right now because of the linker script :')
   -g
 )
 
diff --git a/kernel/mm/physical_mm/physical_mm.c b/kernel/mm/physical_mm/physical_mm.c
index 895a3fd..5b405e6 100644
--- a/kernel/mm/physical_mm/physical_mm.c
+++ b/kernel/mm/physical_mm/physical_mm.c
@@ -22,6 +22,7 @@
 
 /* TODO: Stack based allocation? */
 
+#include <stdatomic.h>
 #include <stdbool.h>
 #include <stdint.h>
 
@@ -31,6 +32,7 @@
 #include <mm/physical_mm.h>
 
 #include <kernel/halt.h>
+#include <kernel/spinlock.h>
 
 extern uint32_t kernel_start;
 extern uint32_t kernel_end;
@@ -39,6 +41,8 @@ uint32_t block_count = 0;
 uint32_t total_free_blocks = 0;
 uint32_t memory_map[MAX_BLOCKS / BITMAP_ENTRY_SIZE];
 
+atomic_flag memory_map_lock;
+
 ALWAYS_INLINE static void
 physical_mm_log_memory_map(free_memory_regions_t *free_memory_regions)
 {
@@ -93,6 +97,8 @@ physical_mm_init(void)
   free_memory_regions_t *free_memory_regions = memory_map_get_free_regions();
   physical_mm_log_memory_map(free_memory_regions);
 
+  spinlock_acquire(&memory_map_lock);
+
   /* All blocks are initially used */
   /* TODO: Move this block to a place after block_count is set. This is why
    * using block_count instead of MAX_BLOCKS wasn't working. */
@@ -109,6 +115,8 @@ physical_mm_init(void)
   uint32_t kernel_size = ((uint32_t) &kernel_end) - ((uint32_t) &kernel_start);
   physical_mm_deinitialize_region((uint32_t) &kernel_start, kernel_size);
 
+  spinlock_release(&memory_map_lock);
+
   total_free_memory -= kernel_size;
   block_count = total_free_memory / BLOCK_SIZE;
   printk("\nphysical_mm", "Total blocks: 0x%x", block_count);
@@ -157,10 +165,13 @@ physical_mm_allocate_block(void)
     return NULL;
   }
 
-  uint32_t block = physical_mm_find_first_free_block();
+  spinlock_acquire(&memory_map_lock);
 
+  uint32_t block = physical_mm_find_first_free_block();
   physical_mm_set_used(block, &total_free_blocks, memory_map);
 
+  spinlock_release(&memory_map_lock);
+
   uint32_t physical_address = block * BLOCK_SIZE;
   return (void *) physical_address;
 }
diff --git a/kernel/mm/virtual_mm/virtual_mm.c b/kernel/mm/virtual_mm/virtual_mm.c
index c69d194..9c239a1 100644
--- a/kernel/mm/virtual_mm/virtual_mm.c
+++ b/kernel/mm/virtual_mm/virtual_mm.c
@@ -107,6 +107,9 @@ virtual_mm_map_page(void *physical_address, void *virtual_address)
     table = (uint32_t *) PDE_GET_TABLE(pd_entry);
 
   uint32_t *pt_entry = &table[GET_PTE_FRAME(virtual_address)];
+  if (PTE_IS_PRESENT(pt_entry))
+    ASSERT_NOT_REACHED(); /* TODO: Mapping previously mapped memory */
+
   *pt_entry = PTE_FRAME((uint32_t) physical_address) | PTE_PRESENT(1)
               | PTE_WRITABLE(1);
 }