From 1734b485b52e5ee0d0130ee9e35f2a3bdebe713c Mon Sep 17 00:00:00 2001
From: "brice.boisson" <brice.boisson@epita.fr>
Date: Wed, 6 Sep 2023 12:51:34 +0900
Subject: [PATCH] Add: Paging

---
 src/idt.c    |  1 -
 src/kernel.c |  3 ++
 src/paging.c | 95 ++++++++++++++++++++++++++++++++++++++++++----------
 src/paging.h |  4 +--
 4 files changed, 82 insertions(+), 21 deletions(-)

diff --git a/src/idt.c b/src/idt.c
index 34433cc..9bac021 100644
--- a/src/idt.c
+++ b/src/idt.c
@@ -96,5 +96,4 @@ void init_idt(void)
     DEBUG_INFO("IDT LOADED");
 
     DEBUG_INFO("ENABLING STI");
-    asm volatile ("sti");
 }
diff --git a/src/kernel.c b/src/kernel.c
index 542a26d..9460275 100644
--- a/src/kernel.c
+++ b/src/kernel.c
@@ -23,6 +23,7 @@ void main(void)
 
 void kernel_main(void)
 {
+
 	init_serial();
 
 	DEBUG_INFO("Starting kernel");
@@ -30,6 +31,8 @@ void kernel_main(void)
 	init_gdt();
 	init_idt();
 	pic_init();
+	make_page();
+	asm volatile ("sti");
 
 	main();
 }
diff --git a/src/paging.c b/src/paging.c
index dd728e4..0a4118e 100644
--- a/src/paging.c
+++ b/src/paging.c
@@ -1,7 +1,10 @@
 #include "paging.h"
 
-struct page_directory_entry page_dir[1024];
-struct page_table_entry page_table[1024];
+#include "debug.h"
+#include "serial.h"
+
+struct page_directory_entry *page_dir = 0x2000; //__attribute__((aligned(4096)));
+struct page_table_entry *page_table = 0x3000; //__attribute__((aligned(4096)));
 
 struct page_directory_param {
     u8 P;
@@ -31,11 +34,18 @@ struct page_directory_entry create_page_directory_entry(struct page_directory_pa
 {
     struct page_directory_entry page_dir;
 
-    page_dir.flags = 2;
+    page_dir.flags = 0;
+    page_dir.flags |= (u8) param.P;
+    page_dir.flags |= (u8) (param.R_W << 1);
+    page_dir.flags |= (u8) (param.U << 2);
+    page_dir.flags |= (u8) (param.PWT << 3);
+    page_dir.flags |= (u8) (param.PCD << 4);
+    page_dir.flags |= (u8) (param.A << 5);
+    page_dir.flags |= (u8) (param.PS << 7);
 
-    page_dir.available = (u8) 10;
+    page_dir.available = (u8) 0;
 
-    page_dir.address = (u32) 24;
+    page_dir.address = (u32) (param.address >> 12);
 
     return page_dir;
 }
@@ -44,35 +54,39 @@ struct page_table_entry create_page_table_entry(struct page_table_param param)
 {
     struct page_table_entry page_table;
 
-    page_table.flags = 2;
+    page_table.flags = 0;
+    page_table.flags = (u8) param.P;
+    page_table.flags |= (u8) (param.R_W << 1);
+    page_table.flags |= (u8) (param.U << 2);
+    page_table.flags |= (u8) (param.PWT << 3);
+    page_table.flags |= (u8) (param.PCD << 4);
+    page_table.flags |= (u8) (param.A << 5);
+    page_table.flags |= (u8) (param.D << 6);
+    page_table.flags |= (u8) (param.PAT << 7);
 
-    page_table.g = (u8) 10;
+    page_table.g = (u8) param.G;
 
     page_table.available = (u8) 0;
 
-    page_table.address = (u32) 24;
+    page_table.address = (u32) param.address;
 
     return page_table;
 }
 
 int make_page(void)
 {
-    page_table[0] = create_page_table_entry((struct page_table_param) {
-                .P = 1, .R_W = 1, .U = 1, .PWT = 1, .PCD = 1,
-                .A = 0, .D = 0, .PAT = 0, .G = 0,
-                .address = 0});
-    
-    for (int i = 1; i < 1024; i++)
+    for (int i = 0; i < 1024; i++)
     {
         page_table[i] = create_page_table_entry((struct page_table_param) {
-                .P = 0, .R_W = 0, .U = 0, .PWT = 0, .PCD = 0,
-                .A = 0, .D = 0, .PAT = 0, .G = 0,
-                .address = 0});
+                    .P = 1, .R_W = 1, .U = 1, .PWT = 0, .PCD = 0,
+                    .A = 0, .D = 0, .PAT = 0, .G = 0,
+                    .address = 1 * i});
     }
 
     page_dir[0] = create_page_directory_entry((struct page_directory_param) {
-                .P = 1, .R_W = 1, .U = 1, .PWT = 1, .PCD = 1,
+                .P = 1, .R_W = 1, .U = 1, .PWT = 0, .PCD = 0,
                 .A = 0, .PS = 0, .address = page_table});
+
     for (int i = 1; i < 1024; i++)
     {
         page_dir[i] = create_page_directory_entry((struct page_directory_param) {
@@ -80,5 +94,50 @@ int make_page(void)
                         .A = 0, .PS = 0, .address = 0});
     }
 
+    // #define DEBUG_PAGING
+    #ifdef DEBUG_PAGING
+    DEBUG_INFO("------ page_dir ------");
+    for (int i = 0; i < 1024; i++)
+    {   
+        int val = ((int *) page_dir)[i];
+        if (i % 64 == 63)
+        {
+            write_serial_nb(val, false);
+            write_serial("\n");
+        }
+        else
+        {
+            write_serial_nb(val, false);
+            write_serial(" ");
+        }
+    }
+
+    DEBUG_INFO("------ page_table ------");
+    for (int i = 0; i < 1024; i++)
+    {
+        u32 val = ((u32 *) page_table)[i];
+        if (i % 64 == 63)
+        {
+            write_serial_nb(val, false);
+            write_serial("\n");
+        }
+        else
+        {
+            write_serial_nb(val, false);
+            write_serial(" ");
+        }
+    }
+    #endif
+
+    DEBUG_INFO("address of Page Directory Array: %d", page_dir);
+    DEBUG_INFO("address of the first Page Table array: %d", page_table);
+
+    asm volatile ("            \
+    mov %0, %%eax           \n \
+    mov %%eax, %%cr3        \n \
+    mov %%cr0, %%eax        \n \
+    or $0x80000000, %%eax   \n \
+    mov %%eax, %%cr0" : "=m" (page_dir));
+
     return 0;
 }
diff --git a/src/paging.h b/src/paging.h
index af9c942..f5ca0db 100644
--- a/src/paging.h
+++ b/src/paging.h
@@ -18,7 +18,7 @@ struct page_table_entry {
 
 int make_page(void);
 
-extern struct page_directory_entry page_dir[1024];
-extern struct page_table_entry page_table[1024];
+// extern struct page_directory_entry page_dir[1024];
+// extern struct page_table_entry page_table[1024];
 
 #endif  /*  !PAGING_H */