From 33d68464b2b1df4d5217c58001cfe7f11fa680b5 Mon Sep 17 00:00:00 2001
From: Adrien Bourmault <neox@os-k.eu>
Date: Tue, 5 Mar 2019 19:54:14 +0100
Subject: [PATCH] LONG MODE MULTIBOOT WORKS gsp!

---
 boot/loader/loader.asm         |  61 ++++++++++++++++-----------------
 boot/loader/mem/management.inc |  28 +++++++++++++++
 build/obj/boot/loader.bin      | Bin 12644 -> 12649 bytes
 3 files changed, 57 insertions(+), 32 deletions(-)

diff --git a/boot/loader/loader.asm b/boot/loader/loader.asm
index 586d18e..09b565b 100644
--- a/boot/loader/loader.asm
+++ b/boot/loader/loader.asm
@@ -38,7 +38,7 @@ _start:
     mov es, ax                          ; And es because it is jealous
     ;mov [Bootdrv], dl
     xor dl, dl
-    jmp 0x0000:main                     ; pas sûr
+    jmp 0x0000:_loader                  ; pas sûr
 
 ;; Magnificent multiboot header for GRUB ------------------------------------ ;;
 MB_header:
@@ -60,7 +60,7 @@ MB_start:
     push eax                            ; 2nd argument is magic number
     push ebx                            ; 1st argument multiboot info pointer
     mov ecx, eax
-    call main
+    call _loader
     add esp, 8                          ; Cleanup arguments "A la MIPS"
     jmp Die                             ; Aufwiedersehen
 
@@ -79,42 +79,39 @@ Die:
     jmp $
 
 ;; THE CODE ----------------------------------------------------------------- ;;
-main:
-    call MB_check
 
+; ---------------------------------------------------------------------------- ;
+;  _loader                                                                     ;
+;                                                                              ;
+;  This is the function that initiates the launch of OS/K. It verifies that    ;
+;  Grub has properly loaded this loader and makes the appropriate setup so     ;
+;  that the kernel will work properly                                          ;
+;                                                                              ;
+;  Why this original design ? Because it works well and prevent us to cause    ;
+;  triple faults by aligment error or too long jumps (yup, it can be a problem);
+;                                                                              ;
+; ---------------------------------------------------------------------------- ;
+_loader:
+    jmp lbegin
+
+%include "boot/loader/multiboot/check.inc"
+lbegin:
+    call MB_check
+    jmp lnext
+
+%include "boot/loader/cpu/cpuid.inc"
+lnext:
     call Check_cpuid
     call Is64Bits
+    jmp lnext2
 
+%include "boot/loader/mem/structures.inc"
+lnext2:
     call Setup_paging
+    jmp lnext3
+%include "boot/loader/mem/management.inc"
 
-    ;; Registering paging
-    mov eax, PML4_table
-    mov cr3, eax                    ; Load PML4 to cr3
-
-    mov eax, cr4
-    or eax, 1 << 5
-    mov cr4, eax                    ; Enable PAE
-
-    ;; Activate long mode
-    mov ecx, 0xC0000080             ; address of MSR
-    rdmsr                           ; read MSR
-    or eax, 1 << 8                  ; LME = 1. (Long Mode Enable)
-    wrmsr                           ; write MSR
-
-    ;; Enable paging
-    mov eax, cr0
-    or eax, 1 << 31                 ; make MSR bit 31 (PG = Paging) to 1 :
-                                    ;    |1|000000000000000000000000000000
-                                    ;     |
-                                    ;     `------ Paging bit
-    mov cr0, eax
-
+lnext3:
     mov dword [0xb8000], 0x2f4b2f4f
     ret
 
-;; INCLUDES ----------------------------------------------------------------- ;;
-%include "boot/loader/cpu/cpuid.inc"
-%include "boot/loader/multiboot/check.inc"
-%include "boot/loader/mem/structures.inc"
-%include "boot/loader/mem/management.inc"
-
diff --git a/boot/loader/mem/management.inc b/boot/loader/mem/management.inc
index 3790a9d..3634666 100644
--- a/boot/loader/mem/management.inc
+++ b/boot/loader/mem/management.inc
@@ -52,3 +52,31 @@ Setup_paging:
     jne .map_p2_table               ; else map the next entry
 
     ret
+
+; ---------------------------------------------------------------------------- ;
+;    Enable long mode and paging                                               ;
+; ---------------------------------------------------------------------------- ;
+Go64:
+    ;; Registering paging
+    mov eax, PML4_table
+    mov cr3, eax                    ; Load PML4 to cr3
+
+    mov eax, cr4
+    or eax, 1 << 5
+    mov cr4, eax                    ; Enable PAE
+
+    ;; Activate long mode
+    mov ecx, 0xC0000080             ; address of MSR
+    rdmsr                           ; read MSR
+    or eax, 1 << 8                  ; LME = 1. (Long Mode Enable)
+    wrmsr                           ; write MSR
+
+    ;; Enable paging
+    mov eax, cr0
+    or eax, 1 << 31                 ; make MSR bit 31 (PG = Paging) to 1 :
+                                    ;    |1|000000000000000000000000000000
+                                    ;     |
+                                    ;     `------ Paging bit
+    mov cr0, eax
+
+    ret
diff --git a/build/obj/boot/loader.bin b/build/obj/boot/loader.bin
index 182a3e209f7fadaa2e907c05e87f344e1c0f846e..faf31098a145ef011cb83636a3ffd826bcb67367 100644
GIT binary patch
delta 155
zcmaEo^fGBezSwKt#-B_Z)@qkB9^PQ^`oxQO|NsAgZ8dR+g8u9Ib0RtqnldmbFa*q<
z6A?Jq@<a(xk>Tt17mtC8UhDx9FO>`!7$!{kz;J<KGY_MTf&2?51_p-L={r6M2rx9C
zU|#%zL4aY$2L&icV6uaum>`Jj*!YtHsI>IS;T<0sCbp^b96rv<(7?^$ukWpY7yy`?
BMb7{L

delta 150
zcmaEv^dxCQzW9q41_p)~DImfML@YI6VA!F-IN8ilo%=W|LjyO1zrMHr;fbvZCNDGp
z|NlQHqVu3B1A_uXz}z_zfpaZSlrSFNVEEDxDAo9rX~SCWQXt>pr5%v3!N|e5@rsOr
p#10KX0fy!i%!@S`1%QStLOFty`3=SRKwQVhpA1Y445d#F0|5RJH?jZ#