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Diffstat (limited to 'kernel/mm/virtual_mm/virtual_mm.c')
-rw-r--r--kernel/mm/virtual_mm/virtual_mm.c43
1 files changed, 26 insertions, 17 deletions
diff --git a/kernel/mm/virtual_mm/virtual_mm.c b/kernel/mm/virtual_mm/virtual_mm.c
index 929b37d..4153065 100644
--- a/kernel/mm/virtual_mm/virtual_mm.c
+++ b/kernel/mm/virtual_mm/virtual_mm.c
@@ -89,7 +89,7 @@ virtual_mm_initialize(void)
void
virtual_mm_map_page(void *physical_address, void *virtual_address)
{
- uint32_t *pd_entry = &current_page_directory[GET_PDE_FRAME(virtual_address)];
+ uint32_t *pd_entry = &current_page_directory[GET_PD_INDEX(virtual_address)];
uint32_t *table = 0;
/* If the pd_entry isn't present, allocate a block for it, zero the table,
@@ -106,16 +106,18 @@ virtual_mm_map_page(void *physical_address, void *virtual_address)
} else
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 */
+ uint32_t *pt_entry = &table[GET_PT_INDEX(virtual_address)];
+ if (PTE_IS_PRESENT(pt_entry)) {
+ printk("debug", "Mapping previously mapped memory: 0x%x", pt_entry);
+ ASSERT_NOT_REACHED();
+ }
*pt_entry = PTE_FRAME((uint32_t) physical_address) | PTE_PRESENT(1)
| PTE_WRITABLE(1);
}
ALWAYS_INLINE uint32_t *
-get_table(uint32_t *pd_entry)
+get_or_make_table(uint32_t *pd_entry)
{
uint32_t *table;
if (!PDE_IS_PRESENT(pd_entry)) {
@@ -123,8 +125,8 @@ get_table(uint32_t *pd_entry)
if (!table)
ASSERT_NOT_REACHED();
- for (uint32_t _ = 0; _ < 1024; _++)
- table[_] = 0;
+ for (uint32_t i = 0; i < 1024; i++)
+ table[i] = 0x0;
*pd_entry = PDE_FRAME((uint32_t) table) | PDE_PRESENT(1) | PDE_WRITABLE(1);
} else
@@ -136,33 +138,38 @@ get_table(uint32_t *pd_entry)
ALWAYS_INLINE void
virtual_mm_find_free_virtual_addresses(uint32_t n)
{
- for (uint32_t i = 0; i < PAGE_DIRECTORY_SIZE; i++) {
- uint32_t current_pd_index = i;
- uint32_t *pd_entry = &current_page_directory[current_pd_index];
- uint32_t *table = get_table(pd_entry);
+ /* Skip the first page directory, we don't wanna touch the first 4MiB. */
+ for (uint32_t i = 1; i < PAGE_DIRECTORY_SIZE; i++) {
+ uint32_t *pd_entry = &current_page_directory[i];
+ uint32_t *table = get_or_make_table(pd_entry);
for (uint32_t j = 0; j < PAGE_TABLE_SIZE; j++) {
uint32_t *pt_entry = &table[j];
if (PTE_IS_PRESENT(pt_entry))
continue;
- /* We found our starting pt_entry */
+ /* We found our starting pt_entry */
printk("debug", "Starting: 0x%x", pt_entry);
uint32_t count = 0;
for (uint32_t k = j; k <= PAGE_TABLE_SIZE; k++) {
/* If we overflow, switch to the consecutive page directory entry */
if (k == PAGE_TABLE_SIZE) {
- pd_entry = &current_page_directory[++current_pd_index];
- table = get_table(pd_entry);
+ if (++i == PAGE_DIRECTORY_SIZE)
+ ASSERT_NOT_REACHED(); /* Ran out of pd_entries */
+
+ pd_entry = &current_page_directory[i];
printk("debug", "Switching pd_entry: 0x%x", pd_entry);
+
+ table = get_or_make_table(pd_entry);
k = 0;
}
+ /* If page table entry is already used, break from the current loop */
uint32_t *pt_entry = &table[k];
if (PTE_IS_PRESENT(pt_entry)) {
- count = 0;
- current_pd_index = i;
- pd_entry = &current_page_directory[current_pd_index];
+ /* Since we have some used address at some point between j and count,
+ * we can't find n consecutive free addresses in between j and the
+ * used block (j + count + 1) */
j += count;
break;
}
@@ -170,6 +177,8 @@ virtual_mm_find_free_virtual_addresses(uint32_t n)
// printk("debug", "Found page: 0x%x", &table[k]);
count++;
if (count == n) {
+ /* TODO: Convert this into a virtual_address using the pd_index &
+ * pt_index */
printk("debug", "Found starting page at: 0x%x", &table[j]);
return;
}