Added paging and fixed several bugs

1 files changed, 152 insertions, 15 deletions

diff --git a/src/kernel/paging/paging.c b/src/kernel/paging/paging.c
index 164372e..6282953 100644
--- a/src/kernel/paging/paging.c
+++ b/src/kernel/paging/paging.c
@@ -1,22 +1,159 @@
-#include <stdint.h>
+#include <stddef.h>
+#include "paging.h"
+#include "kheap.h"
+#include "../lib/lib.h"
+#include "../graphics/graphics.h"
+#include "../interrupts/interrupts.h"
 
-uint64_t page_dir_ptr_tab[4] __attribute__((aligned(0x20)));
-uint64_t page_dir[512] __attribute__((aligned(0x1000)));
-uint64_t page_tab[512] __attribute__((aligned(0x1000)));
+vpage_dir_t *current_vpage_dir = NULL;
+vpage_dir_t *root_vpage_dir = NULL;
 
-void enable_paging() {
-    page_dir_ptr_tab[0] = (uint64_t) &page_dir | 1;
-    page_dir[0] = (uint64_t) &page_tab | 3;
+//Assembly abstraction for more maintainable code
+page_table_t *get_cr3() {
+    unsigned int cr3;
 
-    unsigned int i, address = 0;
-    for (i = 0; i < 512; i++) {
-        page_tab[i] = address | 3;
-        address = address + 0x1000;
+    asm volatile ("movl %%cr3, %%eax" : "=a" (cr3));
+    return (page_table_t *) cr3;
+}
+
+unsigned int get_cr0() {
+    unsigned int cr0;
+
+    asm volatile ("movl %%cr0, %%eax" : "=a" (cr0));
+    return cr0;
+}
+
+void set_cr3(vpage_dir_t *dir) {
+    asm volatile ("movl %%eax, %%cr3"::"a" ((unsigned int) &dir->tables[0]));
+}
+
+void set_cr0(unsigned int new_cr0) {
+    asm volatile ("movl %%eax, %%cr0"::"a" (new_cr0));
+}
+
+void switch_vpage_dir(vpage_dir_t *dir) {
+    set_cr3(dir);
+    set_cr0(get_cr0() | 0x80000000);
+}
+
+vpage_dir_t *mk_vpage_dir() {
+    vpage_dir_t *dir = (vpage_dir_t *) kmalloc_a(sizeof(vpage_dir_t));
+
+    int i;
+    for (i = 0; i < 1024; i++)
+        dir->tables[i] = EMPTY_TAB;
+
+    return dir;
+}
+
+page_table_t *mk_vpage_table() {
+    page_table_t *tab = (page_table_t *) kmalloc_a(sizeof(page_table_t));
+
+    int i;
+    for (i = 0; i < 1024; i++) {
+        tab->pages[i].present = 0;
+        tab->pages[i].rw = 1;
+    }
+
+    return tab;
+}
+
+void vpage_map(vpage_dir_t *dir, unsigned int phys, unsigned int virt) {
+    short id = virt >> 22;
+    page_table_t *tab = mk_vpage_table();
+
+    dir->tables[id] = ((page_table_t *) ((unsigned int) tab | 3));
+
+    int i;
+    for (i = 0; i < 1024; i++) {
+        tab->pages[i].frame = phys >> 12;
+        tab->pages[i].present = 1;
+        phys += 4096;
+    }
+}
+
+void vpage_map_user(vpage_dir_t *dir, unsigned int phys, unsigned int virt) {
+    short id = virt >> 22;
+    page_table_t *tab = mk_vpage_table();
+
+    dir->tables[id] = ((page_table_t *) ((unsigned int) tab | 3 | 4));
+
+    int i;
+    for (i = 0; i < 1024; i++) {
+        tab->pages[i].frame = phys >> 12;
+        tab->pages[i].present = 1;
+        tab->pages[i].user = 1;
+        phys += 4096;
     }
+}
 
+void vpage_fault(struct regs *r) {
     asm volatile ("cli");
-    asm volatile ("movl %cr4, %eax; bts $5, %eax; movl %eax, %cr4"); // CRASH
-    asm volatile ("movl %%eax, %%cr3"::"a" (&page_dir_ptr_tab));
-    asm volatile ("movl %cr0, %eax; orl $0x80000000, %eax; movl %eax, %cr0;");
-    asm volatile ("sti");
+
+    unsigned int no_page = r->err_code & 1;
+    unsigned int rw = r->err_code & 2;
+    unsigned int um = r->err_code & 4;
+    unsigned int re = r->err_code & 8;
+    unsigned int dc = r->err_code & 16;
+
+    if (dc) terminal_write_line(" (Instruction decode error) ");
+    if (!no_page) terminal_write_line(" (No page present) ");
+    if (um) terminal_write_line(" (in user mode) ");
+    if (rw) terminal_write_line(" (Write permissions) ");
+    if (re) terminal_write_line(" (RE) ");
+
+    terminal_write_line("\n");
+}
+
+void page_init() {
+    current_vpage_dir = mk_vpage_dir();
+    root_vpage_dir = current_vpage_dir;
+
+    unsigned int i;
+    for (i = 0; i < 0xF0000000; i += PAGE_S)
+        vpage_map(root_vpage_dir, i, i);
+
+    irq_install_handler(14, vpage_fault);
+    asm volatile ("cli");
+    switch_vpage_dir(root_vpage_dir);
+}
+
+void convert_vpage(vpage_dir_t *kdir) {
+    int i;
+    for (i = 0; i < 1024; i++) {
+        kdir->tables[i] = (page_table_t *) ((unsigned int) kdir->tables[i] | 4);
+
+        if (((unsigned int) kdir->tables[i]) & 1) {
+            int j;
+            for (j = 0; j < 1024; j++)
+                kdir->tables[i]->pages[j].user = 1;
+        }
+    }
+}
+
+void dump_page(vpage_dir_t *dir, unsigned int address) {
+    unsigned short id = address >> 22;
+    terminal_write_line(&"Index salt ="[(unsigned int) dir->tables[id]]);
+}
+
+vpage_dir_t *copy_user_dir(vpage_dir_t *dir) {
+    unsigned int i;
+
+    vpage_dir_t *copy = mk_vpage_dir();
+    memory_copy(copy, root_vpage_dir, sizeof(vpage_dir_t));
+
+    for (i = 0; i < 1024; i++) {
+        if (((unsigned int) dir->tables[i]) & 4) {
+            //vga_fmt("Found a user page at index %d\n", i);
+            page_table_t *tab = (page_table_t *) ((unsigned int) dir->tables[i] & 0xFFFFF000);
+            //vga_fmt("Table at address %X maps to %X\n", (unsigned int) tab, i << 22);
+            //vga_fmt("Virtually mapped from %X\n", tab->pages[0].frame << 12);
+
+            void *buffer = kmalloc_a(PAGE_S);
+            memory_copy(buffer, (void *) (tab->pages[0].frame << 12), PAGE_S);
+            vpage_map_user(copy, (unsigned int) buffer, (unsigned int) i << 22);
+        }
+    }
+
+    return copy;
 }
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