tasking: implement task_kill function, thanks deepseek

include/paging.h

@@ -41,6 +41,10 @@ uint32_t phys_to_virt(uint32_t phys);
 uint32_t* create_page_dir();
 void destroy_page_dir(uint32_t* page_dir);
 
+static inline uint32_t virt_to_phys(void* virt) {
+    return (uint32_t)virt - 0xC0000000;
+}
+
 //page_alloc.c
 void set_bit(uint32_t page_index);
 void clear_bit(uint32_t page_index);

include/task.h

@@ -63,13 +63,14 @@ typedef struct Process
     struct Process* next;      // Следующий процесс
 
     file_t* file_descriptors[MAX_OPEN_FILES];
+    uint8_t zombie;
 } Process;
 
 extern Process* current;
 
 Process* task_create(uint32_t func, uint32_t user_esp, uint32_t ring, uint32_t* pagedir);
+
 void task_kill(Process* proc);
-void     task_exit();
 
 void     scheduler_init();
 void     schedule();

src/mm/page_alloc.c

@@ -17,7 +17,7 @@ void set_bit(uint32_t page_index) {
 // Сбросить бит (пометить страницу как свободную)
 void clear_bit(uint32_t page_index) {
     if (page_index >= PAGE_COUNT) {
-        printf("clear_bit: address out of range\n");
+        printf("clear_bit: address %X out of range\n", page_index);
         return;
     }
 

src/mm/paging.c

@@ -147,26 +147,27 @@ uint32_t* create_page_dir()
     return new_pd;
 }
 
+//TODO: this function is somehow messes up addresses so free_page passes page_nums like 0xF000F into clear_bit
 void destroy_page_dir(uint32_t* page_dir) {
-    // Iterate through all page directory entries
-    for (int i = 0; i < 1024; i++) {
-        if (page_dir[i] & 1) {  // If page table exists
-            uint32_t* page_table = (uint32_t*)(page_dir[i] & 0xFFFFF000);
+    // Temporarily switch to target PD for freeing
+    uint32_t orig_cr3;
+    asm volatile("mov %%cr3, %0" : "=r"(orig_cr3));
+    asm volatile("mov %0, %%cr3" : : "r"(virt_to_phys(page_dir)));
     
-            // Free all user pages (0-767)
-            if (i < 768) {
+    // Free only user-space pages (entries 0-767)
+    for (int i = 0; i < 768; i++) {
+        if (page_dir[i] & PAGE_PRESENT) {
+            uint32_t* pt = (uint32_t*)phys_to_virt(page_dir[i] & ~0xFFF);
             for (int j = 0; j < 1024; j++) {
-                    if (page_table[j] & 1) {
-                        free_page((void*)(page_table[j] & 0xFFFFF000));
+                if (pt[j] & PAGE_PRESENT) {
+                    free_page((void*)(pt[j] & ~0xFFF));
                 }
             }
-            }
-            
-            // Free the page table itself
-            free_page(page_table);
+            free_page((void*)(page_dir[i] & ~0xFFF));
         }
     }
     
-    // Free the page directory
-    free_page(page_dir);
+    // Restore original page directory
+    asm volatile("mov %0, %%cr3" : : "r"(orig_cr3));
+    free_page((void*)virt_to_phys(page_dir));
 }

src/tasking/syscalls.c

@@ -49,8 +49,11 @@ const char* flags_to_mode_str(int flags) {
 int sys_exit(TrapFrame *tf)
 {
     int error_code = tf->ebx;
-
+    printf("killing task\n");
     task_kill(current);
+    asm("sti");
+    while(1){}
+    printf("wtf??");
     return error_code;
 }
 

src/tasking/task.c

@@ -8,6 +8,7 @@
 
 Process* current = 0;
 Process* queue = 0;
+Process* zombie_list = 0;
 
 uint32_t irq_disable_counter = 0;
 uint32_t pid_counter;
@@ -18,7 +19,8 @@ uint32_t task_count;
 
 extern void trapret(void);
 extern void switchProcess(Process* next);
-extern Process* queue;
+//extern Process* queue;
+
 extern uint32_t pid_counter;
 extern uint32_t task_count;
 
@@ -108,18 +110,40 @@ void scheduler_unlock()
         asm volatile("sti");
 }
 
-void schedule()
-{
-    if (!current)
-        return;
+//TODO: there's an issue with this. If there's only one task in the queue (or is it there really?),
+//the scheduler doesn't switch the context to it, but just does nothing
+void schedule() {
+    if (!current) return;
+
+    // Clean any terminated processes in queue
+    Process* prev = NULL;
+    Process* curr = queue;
+    while (curr) {
+        if (curr->state == Terminated) {
+            Process* next = curr->next;
+            if (prev) prev->next = next;
+            else queue = next;
+            
+            destroy_page_dir(curr->pagedir);
+            free_page((void*)virt_to_phys(curr->kstack));
+            free_page((void*)virt_to_phys(curr));
+            
+            curr = next;
+        } else {
+            prev = curr;
+            curr = curr->next;
+        }
+    }
 
     Process* next = current->next;
-    if (!next)
-        next = queue;
-    if (next != current)
-    {
-        switchProcess(next);
+    if (!next) next = queue;
+    while (next && next->state != Ready) {
+        next = next->next;
+        if (!next) next = queue;
     }
+    if (!next || next == current) return;
+
+    switchProcess(next);
 }
 
 void idle()
@@ -149,59 +173,35 @@ void scheduler_init()
     task_create((uint32_t)idle, 0, 0, kernel_tasks_pagedir);
 }
 
-void task_exit()
-{
-    task_kill(current);
-}
+void task_kill(Process* proc) {
+    //that proc != current is sus
+    if (!proc || proc != current) return;
 
-void task_kill(Process* proc)
-{
     scheduler_lock();
+    proc->state = Terminated;
 
-    // Remove process from scheduler queue
-    Process* prev = NULL;
-    Process* curr = queue;
-    
-    while (curr) {
-        if (curr == proc) {
-            if (prev) {
-                prev->next = curr->next;
+    // Remove from process queue
+    if (queue == proc) {
+        queue = proc->next;
     } else {
-                queue = curr->next;
-            }
-            break;
-        }
-        prev = curr;
-        curr = curr->next;
+        Process* prev = queue;
+        while (prev && prev->next != proc) prev = prev->next;
+        if (prev) prev->next = proc->next;
     }
 
-    for (int i = 0; i < MAX_OPEN_FILES; i++) {
-        if (proc->file_descriptors[i] != NULL) {
-            fat_fclose(proc->file_descriptors[i]);
-            free(proc->file_descriptors[i]);
-            proc->file_descriptors[i] = NULL;
-        }
-    }
+    // Schedule next process
+    Process* next = queue;
+    while (next && next->state != Ready) next = next->next;
+    if (!next) next = queue;  // Fallback to idle if needed
     
-    // Free kernel stack
-    if (proc->kstack) {
-        uint32_t kstack_phys = (uint32_t)proc->kstack - 0xC0000000;
-        free_page((void*)kstack_phys);
-    }
+    current = next;
+    set_page_dir(virt_to_phys(next->pagedir));
     
-    // Free process structure
-    uint32_t proc_phys = (uint32_t)proc - 0xC0000000;
-    free_page((void*)proc_phys);
-
-    // Destroy page directory and free user pages
+    // Free resources safely from new context
     destroy_page_dir(proc->pagedir);
-    
-    // Update task count and current process if needed
-    task_count--;
-    if (proc == current) {
-        current = NULL;
-        schedule();  // Switch to another process
-    }
+    free_page((void*)virt_to_phys(proc->kstack));
+    free_page((void*)virt_to_phys(proc));
     
     scheduler_unlock();
+    switchProcess(next);
 }