Implement paging

1 files changed, 65 insertions, 0 deletions

diff --git a/kernel/paging.c b/kernel/paging.c
new file mode 100644
index 0000000..408ced8
--- /dev/null
+++ b/kernel/paging.c
@@ -0,0 +1,65 @@
+#include <stddef.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <string.h>
+#include "frame.h"
+#include "heap.h"
+#include "isr.h"
+#include "paging.h"
+#include "panic.h"
+
+uint32_t *current_directory;
+
+static void page_fault(struct regs_t *regs)
+{
+    volatile uint32_t fault_addr;
+    asm("mov %%cr2, %0" : "=r"(fault_addr));
+    printf("=== Page Fault ===\n");
+    printf("Faulting address: 0x%x\n", fault_addr);
+    /* dump the regs */
+    printf("EAX: 0x%x EBX: 0x%x\n", regs->eax, regs->ebx);
+    printf("ECX: 0x%x EDX: 0x%x\n", regs->ecx, regs->edx);
+    printf("ESP: 0x%x EBP: 0x%x\n", regs->esp, regs->ebp);
+    printf("ESI: 0x%x EDI: 0x%x\n", regs->esi, regs->edi);
+    printf("EIP: 0x%x\n", regs->eip);
+    panic("Page fault!\n");
+}
+
+ void paging_switch_directory(uint32_t *dir)
+{
+    current_directory = dir;
+    extern void do_paging_enable(uint32_t);
+    do_paging_enable((uint32_t)current_directory);
+}
+
+static uint32_t *identity_map_table(uint32_t start, int flags)
+{
+    /* make a page table */
+    uint32_t *table = kmalloc_a(0x1000);
+    /* identity map 4MB */
+    for(uint32_t i = start; i < start + 1024; ++i)
+    {
+        table[i - start] = (i * PAGE_SIZE) | flags;
+    }
+    return table;
+}
+
+void paging_init(void)
+{
+    uint32_t *kernel_directory = kmalloc_a(0x1000);
+    memset(kernel_directory, 0, 0x1000);
+    /* blank the kernel directory */
+    for(int i = 0; i < 1024; ++i)
+    {
+        kernel_directory[i] = PAGE_RW;
+    }
+
+    /* identity map all 4GB */
+    for(int i=0; i < 1024; ++i)
+        kernel_directory[i] = (uint32_t)identity_map_table(i * 1024, PAGE_PRESENT | PAGE_RW) |
+            PAGE_PRESENT | PAGE_RW;
+
+    set_interrupt_handler(14, page_fault);
+
+    paging_switch_directory(kernel_directory);
+}