syscalls: start adding fork syscall, not done yet

include/paging.h

@@ -40,6 +40,7 @@ void set_page_dir(uint32_t new_page_dir);
 uint32_t phys_to_virt(uint32_t phys);
 uint32_t* create_page_dir();
 void destroy_page_dir(uint32_t* page_dir);
+uint32_t* copy_page_dir(uint32_t* page_dir_virt);
 
 static inline uint32_t virt_to_phys(void* virt) {
     return (uint32_t)virt - 0xC0000000;

include/stdio.h

@@ -14,7 +14,7 @@ int printf(const char* __restrict, ...);
 int putchar(int);
 int puts(const char*);
 
-//#define KATAU_DEBUG
+#define KATAU_DEBUG
 
 #ifdef KATAU_DEBUG
 #define debug_log printf

include/task.h

@@ -17,6 +17,8 @@
 
 #define MAX_OPEN_FILES 32
 
+#define KSTACKSIZE 4096
+
 typedef enum TaskState
 {
     Ready,

src/kernel/kernel.c

@@ -218,7 +218,7 @@ void kmain(unsigned int magic, unsigned int info)
 	printf("huy1 points to: 0x%X huy2 points to:0x%X\n", huy, huy2);
 	printf("huy1: %s\nhuy2: %s", huy, huy2);
 
-	exec_from_file("/ebalo/aaa");
+	exec_from_file("/ebalo/forktest");
 
 	while(1)
 	{

src/mm/page_alloc.c

@@ -61,7 +61,7 @@ void* alloc_page() {
                     if(page_num == 0)
                         continue;
                     
-                    debug_log("allocating page %X\n", page_num * PAGE_SIZE);
+                    //debug_log("allocating page %X\n", page_num * PAGE_SIZE);
 
                     page_bitmap[i] |= (1 << j);  // Помечаем как занятый
                     return (void*)(page_num * PAGE_SIZE);

src/mm/paging.c

@@ -188,4 +188,63 @@ void destroy_page_dir(uint32_t* page_dir_virt) {
     // We need its physical address to pass to the physical memory manager.
     debug_log("freeing PD page %X\n", virt_to_phys(page_dir_virt));
     free_page((void*)virt_to_phys(page_dir_virt));
+}
+
+uint32_t* copy_page_dir(uint32_t* page_dir_virt)
+{
+    if(page_dir_virt == NULL)
+        return 0;
+    
+    uint32_t* new_pagedir = create_page_dir();
+    
+    for(int i = 0; i < 768; i++)
+    {
+        uint32_t pde = page_dir_virt[i];
+
+        if(pde & PAGE_PRESENT)
+        {
+            debug_log("PDE %X present\n", pde);
+            uint32_t* new_page_table = (uint32_t*)alloc_page();
+            if(new_page_table == NULL) {
+                return NULL;
+            }
+            
+            // Get original page table (physical address from PDE)
+            uint32_t* orig_page_table = (uint32_t*)phys_to_virt(pde & ~0xFFF);
+
+            for(int j = 0; j < 1024; j++)
+            {
+                uint32_t pte = orig_page_table[j];
+                if(pte & PAGE_PRESENT)
+                {
+                    void* new_phys_page = alloc_page();
+                    if(!new_phys_page)
+                    {
+                        return NULL;
+                    }
+
+                    void* orig_phys_page = (void*)(pte & ~0xFFF);
+
+                    debug_log("copying %X to %X...", orig_phys_page, new_phys_page);
+                    memcpy(new_phys_page, orig_phys_page, PAGE_SIZE);
+                    debug_log("done\n");
+                    new_page_table[j] = (uint32_t)new_phys_page | (pte & 0xFFF);
+                }
+                else
+                {
+                    new_page_table[j] = pte;
+                }
+            }
+            
+            
+            // Set the new PDE in the child's page directory
+            new_pagedir[i] = (uint32_t)virt_to_phys(new_page_table) | (pde & 0xFFF);
+        }
+        else
+        {
+            new_pagedir[i] = pde;
+        }
+    }
+    debug_log("ENDENDENDEND\n");
+    return new_pagedir;
 }

src/tasking/syscalls.c

@@ -2,6 +2,8 @@
 #include <stddef.h>
 #include "../include/stdio.h"
 #include "../include/liballoc.h"
+#include "../include/paging.h"
+#include "../include/string.h"
 
 #define STDIN_FILENO 0
 #define STDOUT_FILENO 1
@@ -56,6 +58,23 @@ int sys_exit(TrapFrame *tf)
     return error_code;
 }
 
+int sys_fork(TrapFrame *tf)
+{
+    debug_log("FORKFORKFORKFORK\n");
+
+    uint32_t* new_pd = copy_page_dir(current->pagedir);
+
+    Process* child = task_create(0, 0, 3, new_pd);
+
+    memcpy(child, current, sizeof(Process));
+    memcpy(child->kstack, current->kstack, KSTACKSIZE);
+
+    child->tf->eax = 0;
+    tf->eax = child->pid;
+
+    return child->pid;
+}
+
 int sys_read(TrapFrame *tf)
 {
     if(tf->ebx < 3)
@@ -145,6 +164,7 @@ int sys_close(TrapFrame *tf)
 
 void handle_syscall(TrapFrame *tf)
 {
+    asm("cli");
     /*
     debug_log("EAX: %X ", tf->eax);
     debug_log("EBX: %X ", tf->ebx);
@@ -157,6 +177,12 @@ void handle_syscall(TrapFrame *tf)
         int r = sys_exit(tf);
         tf->eax = r;
     }
+
+    if(tf->eax == 2)
+    {
+        int r = sys_fork(tf);
+        tf->eax = r;
+    }
     
     if(tf->eax == 3)//read
     {
@@ -179,4 +205,5 @@ void handle_syscall(TrapFrame *tf)
         int r = sys_close(tf);
         tf->eax = r;
     }
+    asm("sti");
 }

src/tasking/task.c

@@ -13,8 +13,6 @@ uint32_t irq_disable_counter = 0;
 uint32_t pid_counter;
 uint32_t task_count;
 
-#define KSTACKSIZE 4096
-
 extern void trapret(void);
 extern void switchProcess(Process* next);