From 8e3411139b27a3421e9ac75c13f14f99f6dd3137 Mon Sep 17 00:00:00 2001
From: Miguel <m.i@gmx.at>
Date: Sun, 2 Sep 2018 00:08:42 +0200
Subject: syscalls

---
 kernel/scheduler.c | 196 +++++++++++++++++++++++++++++------------------------
 1 file changed, 107 insertions(+), 89 deletions(-)

(limited to 'kernel/scheduler.c')

diff --git a/kernel/scheduler.c b/kernel/scheduler.c
index b367825..ee1cea2 100644
--- a/kernel/scheduler.c
+++ b/kernel/scheduler.c
@@ -1,7 +1,3 @@
-// http://hosted.cjmovie.net/TutMultitask.htm
-//
-//
-
 #include "kernel.h"
 #include "mem.h"
 #include "asm/x86.h"
@@ -11,53 +7,70 @@
 #include "fs/fs.h"
 #include "fs/ext2.h"
 
-static volatile int volatile current_task=-1;
+#define NO_TASK 0xffffffff
+
+static volatile uint32_t current_task=NO_TASK;
 
 static volatile struct task_list_struct
 {
-    volatile int parent;
-    volatile bool active;
-    volatile uint32_t esp; // stack pointer of the task;
-    volatile pdirectory *vmem; // number of virtual memory table to switch to
-    volatile bool waiting; 
-    volatile bool skipwait;
-    volatile uint32_t brk;
-    volatile uint32_t esp0;
-
-    volatile bool syscall; // waiting for syscall to be processed.
+    volatile bool active;      // is this slot used (Y/N)
+    volatile uint32_t pid;     // process id (TODO)
+
+    volatile uint32_t parent;  // parent process id
+    volatile uint32_t esp;     // stack pointer of the task
+    volatile uint32_t esp0;    // tss.esp0
+    volatile pdirectory *vmem; // number of virtual memory table
+
+    volatile uint32_t brk;     // memory brk pos
+
+    volatile bool    wait; // waiting for syscall to be processed.
     volatile uint32_t eax;
     volatile uint32_t ebx;
     volatile uint32_t ecx;
     volatile uint32_t edx;
-
     
 }volatile task_list[MAX_TASKS];
 
-volatile int add_task(uint32_t esp, uint32_t vmem)
+volatile int task_reset(uint32_t pid, uint32_t entry, uint32_t stack)
+{
+    uint32_t *stk=task_list[pid].esp;
+    stk[14]=entry;
+    stk[17]=stack;
+}
+
+volatile int add_task(uint32_t parent)
 {
     for(int i=0;i<MAX_TASKS;i++)
     {
 	if(task_list[i].active!=true)
 	{
-	    task_list[i].parent=current_task;
-	    task_list[i].vmem=vmem;
-	    task_list[i].esp  = kballoc(4)+4*4096;
+	    task_list[i].parent=parent;
+
+	    // TODO: do this without paging please!
+	    task_list[i].vmem=vmem_new_space_dir(task_list[parent].vmem); //TODO: what will happen if we get rescheduled!?!?!
+	    task_list[i].esp = kballoc(4)+2*4096; // center
+
+	    // TODO: use own page here and copy it instead of this!
             task_list[i].esp0 = kballoc(4)+4*4096;
-	    task_list[i].active=true;
-	    task_list[i].waiting=false;
-	    task_list[i].skipwait=false;
+
+	    task_list[i].wait=false;
 	    task_list[i].brk=task_list[current_task].brk;
 
-            uint32_t *addi2=(uint32_t *)esp;
-	    addi2+=14;
+            uint32_t *source=(uint32_t *)task_list[parent].esp;
+	    uint32_t *dst=(uint32_t *)task_list[i].esp;
 
-	    for(int x=0;x<15;x++)
+	    for(int x=0;x<100;x++) //TODO:  better copy this page too instead of stack
 	    {
-		task_list[i].esp-=4;
-		uint32_t *addi1=(uint32_t *)task_list[i].esp;
-		*addi1=*addi2;
-		addi2--;
+		*dst=*source;
+		dst++;
+		source++;
 	    }
+
+	    uint32_t *stack=task_list[i].esp;
+	    stack[12]=0x1; 
+	    stack[13]=0; // this task returns pid=0 to the caller
+
+	    task_list[i].active=true; //TODO: LOCK! (also other similar)
 	    return i;
 	}
     }
@@ -65,34 +78,44 @@ volatile int add_task(uint32_t esp, uint32_t vmem)
     kpanic("out of task slots!");
 }
 
-void task_wake_syscall_worker()
-{
-    task_list[2].waiting=false; // todo: context switch immiditly?
-}
+
+/**
+ * kernel space worker thread
+ *
+ * we can get interrupted by an interrupt ANYTIME!
+ *
+ */
 
 void task_syscall_worker()
 {
-    klog("checking if any pending syscalls.");
-
-    for(int i=0;i<MAX_TASKS;i++)
+    while(1)
     {
-	if(task_list[i].syscall)
-	{
-	    klog("task %d waiting on syscall %d. processing...",i,task_list[i].eax);
+	//klog("checking if any pending syscalls.");
 
-	    task_list[2].vmem=task_list[i].vmem; // switch syscall worker to pagedir of calling userprog
-	    x86_set_page_directory(task_list[2].vmem);
-	    syscall_generic(task_list[i].eax,
-			task_list[i].ebx,
-			task_list[i].ecx,
-			task_list[i].edx);
-
-	    task_list[i].syscall=false;
+	for(int i=0;i<MAX_TASKS;i++)
+	{
+	    if(task_list[i].wait)
+	    {
+    //	    klog("task %d waiting on syscall %d. processing...",i,task_list[i].eax);
+		task_list[2].vmem=task_list[i].vmem; // switch syscall worker to pagedir of calling userprog
+		x86_set_page_directory(task_list[2].vmem);
+		uint32_t ret= syscall_generic(task_list[i].eax,
+			    task_list[i].edx,
+			    task_list[i].ecx,
+			    task_list[i].ebx,
+			    i);
+
+		uint32_t *stack=task_list[i].esp;
+		stack[12]=0x1; 
+		stack[13]=ret; 
+	    
+		task_list[i].wait=false;
+	    }
 	}
-    }
 
-    task_list[current_task].waiting=true;
-    __asm__("hlt"); //TODO: force task switch here... via syscall?
+	task_list[2].wait=true;
+	__asm__("int $0x81"); // wake scheduler!
+    }
 }
 
 //
@@ -105,24 +128,22 @@ void task_syscall_worker()
 //
 // we need to return a NEW stack pointer where popa will get the registers the new task requires
 //
-static int first=1;
 volatile uint32_t my_scheduler(uint32_t oldesp)
 {
-
-    if(!first)
-    {
-	task_list[current_task].esp=oldesp;
-    }
-	first=0;
+    // 
+    static bool first=true;
+    if(current_task==NO_TASK)return oldesp;
+    if(!first) task_list[current_task].esp=oldesp;
+    first=false;
+    //
 
     for(int i=0;i<MAX_TASKS;i++)
     {
 	int pid=(current_task+1+i)%MAX_TASKS; // schedule round robin style
 
-	if(task_list[pid].active && !task_list[pid].waiting && !task_list[pid].syscall)
+	if(task_list[pid].active && !task_list[pid].wait) // find active non-blocked task
 	{
-	    if(current_task!=pid)
-		    klog("switch from %d to %d", current_task, pid);
+	    //if(current_task!=pid)klog("switch from %d to %d", current_task, pid);
 
 	    current_task=pid;
 	    install_tss(task_list[pid].esp0);
@@ -136,28 +157,22 @@ volatile uint32_t my_scheduler(uint32_t oldesp)
     kpanic("nothing to schedule!");
 }
 
-// this gets called by our clock interrupt regularly!
-volatile uint32_t task_switch_next(uint32_t oldesp)
+volatile uint32_t task_syscall(uint32_t eax,uint32_t ebx, uint32_t ecx, uint32_t edx)
 {
-    // check if multitasking has been started
-    if(current_task<0)return oldesp; 
-    return my_scheduler(oldesp);
-}
-
-volatile uint32_t task_syscall(uint32_t eax,uint32_t ebx, uint32_t ecx, uint32_t edx,uint32_t oldesp)
-{
-    task_list[current_task].syscall=true;
+    task_list[current_task].wait=true;
     task_list[current_task].eax=eax;
     task_list[current_task].ebx=ebx;
     task_list[current_task].ecx=ecx;
     task_list[current_task].edx=edx;
-    return my_scheduler(oldesp);
+
+    task_list[2].wait=false;
 }
 
 //TODO: free vmem too!
 //TODO: notify waiting parent when child finished;
 volatile uint32_t task_exit(uint32_t oldesp)
 { 
+    /*
 
     task_list[current_task].active=false;
     int parent_pid=task_list[current_task].parent;
@@ -174,8 +189,8 @@ volatile uint32_t task_exit(uint32_t oldesp)
 	}
 	else
 	{
-	   klog("[%d] skipwait", parent_pid);
-	   task_list[parent_pid].skipwait=true;
+//	   klog("[%d] skipwait", parent_pid);
+//	   task_list[parent_pid].skipwait=true;
 	}
 	
     }
@@ -183,11 +198,12 @@ volatile uint32_t task_exit(uint32_t oldesp)
     vmem_free_dir(task_list[current_task].vmem);
 
     return my_scheduler(oldesp);
+    */
 
 }
 
 volatile uint32_t task_wait(uint32_t oldesp)
-{ 
+{ /*
     klog("[%d] wait", current_task);
     if(task_list[current_task].skipwait)
     {
@@ -198,13 +214,14 @@ volatile uint32_t task_wait(uint32_t oldesp)
 	task_list[current_task].waiting=true;
     }
     return my_scheduler(oldesp);
+    */
 }
 
-volatile uint32_t task_fork(uint32_t oldesp)
+volatile uint32_t task_fork(uint32_t pid)
 { 
-   int pid=add_task(oldesp,vmem_new_space_dir(task_list[current_task].vmem));
+   int ret=add_task(pid);
    klog("[%d] forked -> [%d] (free blocks remaining: %d )", current_task, pid,mem_get_free_blocks_count());
-   return pid;
+   return ret;
 }
 
 // init task (root of all other tasks / processes) //
@@ -220,27 +237,28 @@ volatile void scheduler_init(pdirectory *dir)
     // this is our main user task on slot 0 
     task_list[0].parent=0;
     task_list[0].active=true;
-    task_list[0].waiting=false;
+    task_list[0].wait=false;
     task_list[0].vmem=dir;
-    task_list[0].esp = kballoc(4)+4*4096;
+    task_list[0].esp = kballoc(4)+3*4096;
     task_list[0].esp0 = kballoc(4)+4*4096;
 
-    task_list[1].parent=0;
-    task_list[1].active=true;
-    task_list[1].waiting=false;
-    task_list[1].vmem=dir;
-    task_list[1].esp = kballoc(4)+4*4096; 
-    task_list[1].esp0 = 0; // not needed by kernel space tasks
+//    task_list[1].parent=0;
+//    task_list[1].active=true;
+//    task_list[1].waiting=false;
+//    task_list[1].syscall=false;
+//    task_list[1].vmem=dir;
+//    task_list[1].esp = kballoc(4)+3*4096; 
+//    task_list[1].esp0 = 0; // not needed by kernel space tasks
 
     task_list[2].parent=0;
     task_list[2].active=true;
-    task_list[2].waiting=false;
+    task_list[2].wait=false;
     task_list[2].vmem=dir;
-    task_list[2].esp = kballoc(4)+4*4096; 
+    task_list[2].esp = kballoc(4)+3*4096; 
     task_list[2].esp0 = 0; // not needed by kernel space tasks
 
     task_pusha(task_list[2].esp);
-    task_pusha(task_list[1].esp);
+//    task_pusha(task_list[1].esp);
     task_pusha(task_list[0].esp);
 
     // finally enable interrrupts so the scheduler is called (by timer)
-- 
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