From be080af906d104a6fd0a40038d465491775a3393 Mon Sep 17 00:00:00 2001
From: Mathieu Maret <mathieu.maret@gmail.com>
Date: Thu, 28 Oct 2021 18:19:35 +0200
Subject: [PATCH] Fix initial area setup

The inital kernel stack was not page aligned and thus was found in 2
area
---
 arch/x86/boot/boot.asm |  2 +-
 core/allocArea.c       | 30 +++++++++++++++++++-----------
 2 files changed, 20 insertions(+), 12 deletions(-)

diff --git a/arch/x86/boot/boot.asm b/arch/x86/boot/boot.asm
index 5f9b676..7588d78 100644
--- a/arch/x86/boot/boot.asm
+++ b/arch/x86/boot/boot.asm
@@ -28,7 +28,7 @@ align 4
 ; stack is properly aligned and failure to align the stack will result in
 ; undefined behavior.
 section .bss
-align 16
+align 4096
 stack_bottom:
 resb 16384 ; 16 KiB
 stack_top:
diff --git a/core/allocArea.c b/core/allocArea.c
index 4c5bb20..73df03a 100644
--- a/core/allocArea.c
+++ b/core/allocArea.c
@@ -6,14 +6,11 @@
 #include "mem.h"
 #include "stdarg.h"
 
-
 static struct memArea *freeArea;
 static struct memArea *usedArea;
 
 static int areaMergeFreeArea(struct memArea *prev, struct memArea *next);
 
-
-//Kernel stack is inside firstMemUsed-lastUsed
 void areaInit(vaddr_t firstMemUsed, vaddr_t lastUsed, vaddr_t stackBottom, vaddr_t stackTop)
 {
     list_init(freeArea);
@@ -27,14 +24,23 @@ void areaInit(vaddr_t firstMemUsed, vaddr_t lastUsed, vaddr_t stackBottom, vaddr
     if (areaAddr != descAddr && areaAddr != entryAddr)
         areaAdd(areaAddr, 1, FALSE);
 
-    int nbPagesKernel = DIV_ROUND_UP((lastUsed - firstMemUsed), PAGE_SIZE);
+    //kernel bootstrap part
+    int nbPagesKernel = DIV_ROUND_UP((stackBottom - firstMemUsed), PAGE_SIZE);
     areaAdd(ALIGN_DOWN(firstMemUsed, PAGE_SIZE), nbPagesKernel, FALSE);
-    if(stackBottom > lastUsed){
-        int nbPagesStack = DIV_ROUND_UP((stackTop - stackBottom), PAGE_SIZE);
-        areaAdd(ALIGN_DOWN(stackBottom, PAGE_SIZE), nbPagesStack, FALSE);
-    }
+
+    //Initial kernel stack
+    int nbPagesStack = DIV_ROUND_UP((stackTop - stackBottom), PAGE_SIZE);
+    areaAdd(ALIGN_DOWN(stackBottom, PAGE_SIZE), nbPagesStack, FALSE);
+
+    // Rest of kernel code
+    int nbPagesKernelCode = DIV_ROUND_UP((lastUsed - stackTop), PAGE_SIZE);
+    areaAdd(ALIGN_DOWN(stackTop, PAGE_SIZE), nbPagesKernelCode, FALSE);
+
+    // Rest of virtual mem is free
     int nbFreePages = DIV_ROUND_UP((AREA_MEM_TOP - areaAddr), PAGE_SIZE);
-    areaAdd(ALIGN_DOWN(areaAddr + PAGE_SIZE, PAGE_SIZE), nbFreePages , TRUE);
+    areaAdd(ALIGN_DOWN(areaAddr + PAGE_SIZE, PAGE_SIZE), nbFreePages, TRUE);
+
+    // Create allocBank for the rest of the system
     allocPopulate();
 }
 
@@ -183,9 +189,11 @@ int areaFree(vaddr_t addr)
         pr_info("Cannot find memArea associated to %p\n", addr);
         return -1;
     }
-    for(uint i = 0; i < area->nbPages; i++){
-        pageUnmap( area->startAddr + i * PAGE_SIZE);
+
+    for (uint i = 0; i < area->nbPages; i++) {
+        pageUnmap(area->startAddr + i * PAGE_SIZE);
     }
+
     list_delete(usedArea, area);
     insertSorted(&freeArea, area);