From 152f14654bfb438d074833e3c8d5392d300f5095 Mon Sep 17 00:00:00 2001
From: Loic Guegan <manzerbredes@mailbox.org>
Date: Wed, 28 Apr 2021 10:46:36 +0200
Subject: [PATCH] Debug trampoline and paging

---
 src/boot/boot.S         | 12 ++++++++----
 src/boot/trampoline.cc  | 13 ++++++++++++-
 src/boucane.cc          | 21 ++++++++++++++-------
 src/core/paging.cc      | 12 ++++--------
 src/core/paging.hpp     |  3 ++-
 src/include/boucane.hpp |  7 ++++++-
 6 files changed, 46 insertions(+), 22 deletions(-)

diff --git a/src/boot/boot.S b/src/boot/boot.S
index 73ee637..d8795d0 100644
--- a/src/boot/boot.S
+++ b/src/boot/boot.S
@@ -1,8 +1,6 @@
 .globl  _start
-.globl MB_INFO
 .extern _bss_start
 .extern _bss_end
-.extern higherhalf
 
 .section .multiboot
 
@@ -35,7 +33,7 @@ mb_header_start:
 # ----------- End tag
 # ----------- Ask framebuffer tag
 .align 8
-.short 6
+.short 5
 .short 1
 .int 20
 .int 0
@@ -55,6 +53,7 @@ MB_INFO: # Will contains the Multiboot2 information data structure address
 
 _start:
 mov %ebx, (MB_INFO)
+
 # ----- Setup PAE Paging (identity on the first 10MB)
 mov $8192, %ecx # 8*4096/4 (8 tables of 4096 byte each divide by 4 because of movl)
 mov $0, %eax
@@ -122,8 +121,12 @@ mov %ax, %gs
 mov %ax, %ss
 mov $__stack_pma, %esp
 
-# Setup 
+# Setup
+movq (MB_INFO), %rdi
+mov $0xFFFFFFFF,%rax
+and %rax, %rdi
 call trampoline
+movq %rax, (MB_INFO)
 mov $__kernel_vma, %rsp
 
 # Zeroing the .bss section
@@ -138,6 +141,7 @@ start_zeroing:
 end_zeroing:
 
 # Launch kernel
+movq (MB_INFO), %rdi
 call boucane
 
 # GDT
diff --git a/src/boot/trampoline.cc b/src/boot/trampoline.cc
index b03bd43..a75b472 100644
--- a/src/boot/trampoline.cc
+++ b/src/boot/trampoline.cc
@@ -10,6 +10,10 @@
 /// @brief Define where first PAE paging paging will be
 u64 trampoline_next_page;
 
+/// @brief Ensure
+#define MAX_MB_INFOS 4096
+u8 mb_infos[MAX_MB_INFOS];
+
 u64 trampoline_paging_allocate_table(){
     for(u64 i=0;i<512;i++)
         ((u64*)trampoline_next_page)[i]=0;
@@ -63,7 +67,12 @@ void trampoline_paging_allocate_addr(u64* pml4_table, u64 virt, u64 phy, u16 opt
 /**
  * Setup High-Half Kernel Paging
  */
-extern "C" void trampoline(){
+extern "C" u8* trampoline(u8* mb_infos_addr){
+    // Save mb infos before anything else
+    for(int i=0;i<MAX_MB_INFOS;i++){
+        mb_infos[i]=mb_infos_addr[i];
+    }
+
     u64 kernel_vma,stack_pma;
     asm("movq $__kernel_vma, %0":"=r"(kernel_vma));
     asm("movq $__userspace_pma, %0":"=r"(trampoline_next_page));
@@ -91,4 +100,6 @@ extern "C" void trampoline(){
         "movq %0, %%rax        \n\t"
         "movq %%rax, %%cr3     \n\t"
         :: "r" (pml4));
+        
+    return mb_infos;
 }
\ No newline at end of file
diff --git a/src/boucane.cc b/src/boucane.cc
index 0209281..1e58d65 100644
--- a/src/boucane.cc
+++ b/src/boucane.cc
@@ -9,18 +9,25 @@
 #include "libs/stdio.hpp"
 #include "core/asm.hpp"
 
+u64 kernel_vma,stack_pma,userspace_pma;
 
-extern u32 MB_INFO;
-extern u64 res_binary_res_terminus_psf_start;
+extern "C" void boucane(u64 mb_info){
+    // Init linker variables
+    asm volatile ("movq $__kernel_vma, %0":"=m"(kernel_vma));
+    asm volatile ("movq $__userspace_pma, %0":"=m"(userspace_pma));
+    asm volatile ("movq $__stack_pma, %0":"=m"(stack_pma));
+    asm volatile ("call load_gdt");
 
-extern "C" void boucane(){
     // Init data structures
-    LOAD_GDT();
     paging_enable();
     idt_enable_interrupt();
 
+    // Looking for framebuffer
+    vga_t_init();
+    vga_t_clear();
     FRAMEBUFFER fb_info;
-    if(mb2_find_framebuffer((u32*)&MB_INFO, &fb_info)){
+
+    if(mb2_find_framebuffer((u32*)mb_info, &fb_info)){
         if(fb_info.bpp>16){
             FB_CFG conf;
             conf.depth=fb_info.bpp;
@@ -33,8 +40,8 @@ extern "C" void boucane(){
             __putchar=psf_putchar;
         }
     }
-    vga_t_init();
-    vga_t_clear();
+
+    // Booting!
     printk("Booting Boucane v%d.%d.%d\n",VERSION_MAJOR,VERSION_MINOR, VERSION_PATH);
  
 
diff --git a/src/core/paging.cc b/src/core/paging.cc
index 73a5c63..da442bf 100644
--- a/src/core/paging.cc
+++ b/src/core/paging.cc
@@ -4,7 +4,6 @@
 #include "libs/string.hpp"
 
 char paging_status[PAGING_MAX_PAGE / 8];
-u64 kernel_vma,stack_pma,userspace_pma;
 u64 kpages[MAX_TABLES][512] __attribute__((aligned(4096)));
 int kpages_next=1; // First page is for the pml4
 
@@ -16,10 +15,6 @@ u64* paging_allocate_table(){
 }
 
 void paging_enable() {
-    // Init linker variables
-    asm("movq $__kernel_vma, %0":"=r"(kernel_vma));
-    asm("movq $__userspace_pma, %0":"=r"(userspace_pma));
-    asm("movq $__stack_pma, %0":"=r"(stack_pma));
 
     // Init status
     for (int i = 0; i < PAGING_MAX_PAGE / 8; i++) {
@@ -28,9 +23,10 @@ void paging_enable() {
 
     // Init tables
     for(int i=0;i<MAX_TABLES;i++){
-        memset(kpages[i], 0, 512*64);
+        for(int j=0;j<512;j++)
+            kpages[i][j]=0;
     }
- 
+
     // Allocate paging for the kernel (to not override the source
     // code during the next paging_allocate_table() calls)
     paging_allocate_contiguous(userspace_pma/4096);
@@ -41,7 +37,7 @@ void paging_enable() {
     }
     // 4096 bytes stack
     paging_allocate_addr(kpages[0],kernel_vma-4096,stack_pma,0x3,0);
-
+    
     // Load new pml4
     u64 kpage_phy=((u64)kpages[0]-kernel_vma);
     asm volatile(
diff --git a/src/core/paging.hpp b/src/core/paging.hpp
index 089bd47..01e45a7 100644
--- a/src/core/paging.hpp
+++ b/src/core/paging.hpp
@@ -24,9 +24,10 @@
 /// @brief All PAE table structures are allocated here
 extern u64 kpages[MAX_TABLES][512];
 
-/// @brief Various variables from the linker
+/// cf boucane.hpp
 extern u64 kernel_vma,stack_pma,userspace_pma;
 
+
 /**
  * Setup and enable PAE paging
  */
diff --git a/src/include/boucane.hpp b/src/include/boucane.hpp
index f178f42..79975a3 100644
--- a/src/include/boucane.hpp
+++ b/src/include/boucane.hpp
@@ -10,4 +10,9 @@
 #include "libs/stdio.hpp"
 #include "libs/string.hpp"
 
-#define LOAD_GDT() asm("call load_gdt")
\ No newline at end of file
+/// @brief Various variables from the linker
+extern u64 kernel_vma,stack_pma,userspace_pma;
+
+/// @brief Binary references
+extern u64 res_binary_res_terminus_psf_start;
+extern u64 res_binary_res_terminus_psf_end;