Begin multitasking refactor to support ring-3 TSS
diff --git a/src/kernel/paging.c b/src/kernel/paging.c
index 50ee738..f1fd125 100644
--- a/src/kernel/paging.c
+++ b/src/kernel/paging.c
@@ -12,6 +12,7 @@
static uint first_page_table[1024] __attribute__((aligned(4096)));
uint kernel_page_directory[1024] __attribute__((aligned(4096)));
+
/* frame utils */
#define BITS 32
@@ -94,16 +95,41 @@
uint *get_or_create_table(uint *dir, uint table, bool user, bool rw)
{
- if (dir[table] >> 12)
+ // If used AND NOT 4mb page (see figure 4-4, page 115 of Intel
+ // manual volume 3)
+ if (dir[table] & 1 && dir[table] ^ 1 << 7)
{
- return (uint *)(size_t)PHYS_TO_VIRT((dir[table] ^ 0xfff));
+ return (uint *)(size_t)PHYS_TO_VIRT((dir[table] & ~0xfff));
}
- uint *page_table = kmalloc_a(sizeof(uint[1024]));
+ uint *page_table = malloc(sizeof(uint[1024]));
dir[table] = VIRT_TO_PHYS(page_table) | 1 | rw << 1 | user << 2;
return page_table;
}
+void unmap_all_frames(uint page_table_p)
+{
+ uint *table = (uint *)PHYS_TO_VIRT(page_table_p);
+
+ for (int i = 0; i < 1024; i++)
+ {
+ if (table[i] & 1)
+ {
+ clear_frame(table[i] >> 12);
+ }
+ }
+}
+
+void destroy_page_table_if_exists(uint *dir, uint table)
+{
+ // If used AND NOT 4mb page
+ if (dir[table] & 1 && dir[table] ^ 1 << 7)
+ {
+ unmap_all_frames(dir[table] >> 12);
+ free((void *)PHYS_TO_VIRT(dir[table] >> 12));
+ }
+}
+
void unmap_page(uint *dir, void *virt)
{
uint page = ((size_t)virt / 0x1000) % 1024;
@@ -171,6 +197,26 @@
/* paging stuff */
+uint *new_page_directory_v()
+{
+ // Only call this AFTER allocator + paging are initialized!
+ uint *dir = malloc(1024 * 4);
+ map_4mb(kernel_page_directory, (size_t)KERNEL_VIRTUAL_BASE, 0, false,
+ false);
+
+ return dir;
+}
+
+void free_page_directory_v(uint *dir_v)
+{
+ for (int i = 0; i < 1024; i++)
+ {
+ destroy_page_table_if_exists(dir_v, i);
+ }
+
+ free(dir_v);
+}
+
void init_paging()
{
memset(kernel_page_directory, 0, 1024 * 4);
@@ -178,6 +224,7 @@
false);
load_page_directory((uint)kernel_page_directory - 0xC0000000);
+
add_interrupt_handler(14, page_fault);
}