split out paging functions

1 files changed, 69 insertions, 0 deletions

diff --git a/kc/boot/loader_paging.c b/kc/boot/loader_paging.c
new file mode 100644
index 0000000..8ab40c3
--- /dev/null
+++ b/kc/boot/loader_paging.c
@@ -0,0 +1,69 @@
+#include "loader_paging.h"
+
+uint64_t *get_page_map(void)
+{
+    uint64_t map;
+    __asm__("mov %%cr3, %0" : "=r"(map));
+    return (uint64_t *)(page_address(map, 1));
+}
+
+void set_page_map(uint64_t *map)
+{
+    __asm__ volatile
+        (
+         "pushf\n\t"
+         "cli\n\t"
+         "mov %0, %%cr3\n\t"
+         "popf\n\t"
+         :
+         : "r"(map));
+}
+
+uint64_t *get_page_table(uint64_t *map, uint64_t virt, int level)
+{
+    if ((level < 1) || (level > PAGE_MAP_LEVELS))
+    {
+        return NULL;
+    }
+
+    for (int i = PAGE_MAP_LEVELS; i > level; i--)
+    {
+        if (!map[pte_index(virt, i)])
+        {
+            map[pte_index(virt, i)] =
+                (uint64_t)new_page_table()|PAGE_PR|PAGE_WR;
+        }
+
+        map = (uint64_t *)page_address(map[pte_index(virt, i)], 1);
+    }
+
+    return map;
+}
+
+uint64_t *get_page_entry(uint64_t *map, uint64_t virt)
+{
+    int level = 1;
+    uint64_t *table = get_page_table(map, virt, level);
+    return &table[pte_index(virt, level)];
+}
+
+void map_page(void *map,
+        uint64_t virt,
+        uint64_t phys,
+        enum page_type type)
+{
+    *get_page_entry(map, virt) = phys | type;
+}
+
+void map_pages(void *map,
+        uint64_t virt,
+        uint64_t phys,
+        enum page_type type,
+        size_t size)
+{
+    for (size_t offset = 0; offset < size; offset += page_size(1))
+    {
+        map_page(map, virt + offset, phys + offset, type);
+    }
+}
+