5 files changed, 90 insertions, 1 deletions

diff --git a/kernel/boot.s b/kernel/boot.s
index bc42a5d..80f8be9 100644
--- a/kernel/boot.s
+++ b/kernel/boot.s
@@ -4,6 +4,7 @@ global kboot
 global register_isr
 global tss
 extern kmain
+extern paging_init
 extern syscall_init
 extern timer_init
 extern traps_init
@@ -24,6 +25,7 @@ kboot:
   mov esp, 0x80000
   ; setup descriptor tables
   call flush_gdt
+  call paging_init
   call flush_idt
   ; last minute setup, then transfer to kmain
   call timer_init
diff --git a/kernel/kmain.c b/kernel/kmain.c
index 4bfd129..ece7012 100644
--- a/kernel/kmain.c
+++ b/kernel/kmain.c
@@ -3,7 +3,6 @@
 #include <stdint.h>
 #include <sys/types.h>
 
-
 uint32_t ticks = 0;
 
 extern void userspace_init(void);
diff --git a/kernel/page.s b/kernel/page.s
new file mode 100644
index 0000000..4e40822
--- /dev/null
+++ b/kernel/page.s
@@ -0,0 +1,55 @@
+global paging_init
+
+align 4096
+page_dir:
+  times 4096 db 0
+
+align 4096
+page_tables:
+  ; two page tables
+  times 4096 db 0
+  times 4096 db 0
+.end:
+
+; here, we initialize paging. since the IDT
+; has yet to be populated, we must take extra
+; care as we can't afford to trigger a page
+; fault.
+paging_init:
+  push ebp
+  mov ebp, esp
+  push ebx
+  ; populate the page directory
+  mov eax, page_tables
+  or eax, 0x007
+  mov [page_dir], eax
+  mov eax, (page_tables+4096)
+  or eax, 0x007
+  mov [page_dir+4], eax
+  ; populate the page tables
+  mov ebx, page_tables
+  mov ecx, ((page_tables.end-page_tables)/4)
+  mov edx, 0
+.loop:
+  mov eax, edx
+  or eax, 0x003
+  cmp edx, 0x100000
+  jb .skip
+  or eax, 0x004
+.skip:
+  mov [ebx], eax
+  dec ecx
+  jz .end
+  add ebx, 4
+  add edx, 4096
+  jmp .loop
+.end:
+  ; load the page directory and enable paging
+  mov eax, page_dir
+  mov cr3, eax
+  mov eax, cr0
+  or eax, 0x80000000
+  mov cr0, eax
+  pop ebx
+  pop ebp
+  ret
diff --git a/kernel/panic.s b/kernel/panic.s
new file mode 100644
index 0000000..f4e0f26
--- /dev/null
+++ b/kernel/panic.s
@@ -0,0 +1,20 @@
+;
+; panic.s - provides panic() which disables
+; interrupts and halts the system. currently used
+; mainly for debugging, will eventually be expanded
+; to display some useful information on the
+; console.
+;
+
+global panic
+extern printf
+
+panic:
+  push ebp
+  mov ebp, esp
+  push .msg
+  call printf
+  add esp, 4
+  cli
+  hlt
+.msg: db "Kernel panic!", 10, 0
diff --git a/kernel/traps.s b/kernel/traps.s
index ba9814c..0381ee8 100644
--- a/kernel/traps.s
+++ b/kernel/traps.s
@@ -7,6 +7,8 @@ global syscall_init
 global traps_init
 extern call_table
 extern idt
+extern panic
+extern printf
 extern register_isr
 
 %macro SAVE 0
@@ -179,7 +181,18 @@ exc_gprot:
 
 exc_pagef:
   SAVE_ERR
+
+  push ebx
+  mov ebx, cr2
+  push ebx
+  push .fmt
+  call printf
+  add esp, 8
+  call panic
+
   RESTORE_ERR
+.fmt:
+  db "Page Fault (illegal memory access: 0x%08x:0x%02x)", 10, 0
 
 exc_mathf:
   SAVE