From 3259715b0ed510ededeeb8240cc3bbdcdfc362a3 Mon Sep 17 00:00:00 2001
From: Loic Guegan <manzerbredes@mailbox.org>
Date: Sat, 17 Apr 2021 16:43:28 +0200
Subject: [PATCH] Improve task stack management

---
 src/bringelle.c      | 13 +++++++------
 src/core/scheduler.c | 11 +++++++++--
 src/core/scheduler.h |  2 +-
 3 files changed, 17 insertions(+), 9 deletions(-)

diff --git a/src/bringelle.c b/src/bringelle.c
index 17d3845..22791f3 100644
--- a/src/bringelle.c
+++ b/src/bringelle.c
@@ -5,6 +5,8 @@
 #include "core/paging.h"
 #include "core/scheduler.h"
 
+#define TASK_WAIT 50000000
+
 extern void interrupt_enable();
 
 void utask(){
@@ -13,7 +15,7 @@ void utask(){
   msg[1]='\0';
   while(1){
       asm("mov $0x1, %%eax;int $0x30"::"b"(msg));
-      for(int i=0;i<5000;i++){
+      for(int i=0;i<TASK_WAIT;i++){
 
       }
   }
@@ -25,7 +27,7 @@ void utask2(){
   msg[1]='\0';
   while(1){
       asm("mov $0x1, %%eax;int $0x30"::"b"(msg));
-      for(int i=0;i<5000;i++){
+      for(int i=0;i<TASK_WAIT;i++){
         
       }
   }
@@ -51,10 +53,9 @@ void bringelle(){
   // Utask
   print("Launch user tasks \n");
 
-  int* page_dir=paging_allocate(2);
-  task_create(page_dir, utask,100, 0xFF);
-  int* page_dir2=paging_allocate(2);
-  task_create(page_dir2, utask2,100,0xFF);
+  task_create(utask,100);
+  task_create(utask2,100);
+
 
   scheduler_start();
 
diff --git a/src/core/scheduler.c b/src/core/scheduler.c
index 224c20d..59f3b9d 100644
--- a/src/core/scheduler.c
+++ b/src/core/scheduler.c
@@ -80,11 +80,16 @@ void clock(){
     schedule(stack);
 }
 
-void task_create(int *page_dir, void *task, int task_size, int stack_offset){
+void task_create(void *task, int task_size){
   if(nproc<=MAX_PROC){
+    // Allocate at least 1 page and 1 page for the user stack
+    int allocated=1+task_size/4096+1;
+    int* page_dir=paging_allocate(allocated);
+
     // Compute various addresses
     void *entry_point=PAGING_ENTRY_POINT_VIRT;
-    void *ustack=(void*)(PAGING_ENTRY_POINT_VIRT+stack_offset);
+    // User stack start at the end of last allocated page (since addresses are going down)
+    void *ustack=(void*)(PAGING_ENTRY_POINT_VIRT+allocated*4096);
 
     // Load the task into memory
     memcpy(task,PAGING_ENTRY_POINT_PHY(page_dir), task_size);
@@ -119,6 +124,8 @@ void task_create(int *page_dir, void *task, int task_size, int stack_offset){
     p->page_dir=page_dir;
     nproc++;
   }
+  else
+    print("Could not create more task!");
 }
 
 void scheduler_start(){
diff --git a/src/core/scheduler.h b/src/core/scheduler.h
index 62d6561..3410ba1 100644
--- a/src/core/scheduler.h
+++ b/src/core/scheduler.h
@@ -47,7 +47,7 @@ void schedule(u32 *stack);
 /**
  * Create a new task to be schedule
  */
-void task_create(int *page_dir, void *task, int task_size, int stack_offset);
+void task_create(void *task, int task_size);
 
 /**
  * Stack the scheduler starting by task with PID 0