tasking: isolate ring3 tasks

include/paging.h

@@ -58,7 +58,8 @@ void *get_physaddr(void *virtualaddr);
 uint32_t get_pte(void *virtualaddr);
 void map_page(void* physaddr, void* virtualaddr, unsigned int flags);
 void unmap_page(void *virtualaddr);
+int map_page_in_directory(uint32_t* pd_virt_addr, void* phys_addr, void* virt_addr, uint32_t flags);
 void map_kernel_page(void* virtualaddr, unsigned int flags);
-void* setup_user_process(void* user_code_phys, uint32_t* user_stack_top);
+void* setup_user_process(uint32_t* pd, void* user_code_phys, uint32_t* user_stack_top);
 
 #endif

include/task.h

@@ -61,7 +61,7 @@ typedef struct Process
     uint32_t*  page_directory; // Директория страниц
 } Process;
 
-Process* task_create(uint32_t func, void** args, uint32_t arg_count, uint32_t ring);
+Process* task_create(uint32_t func, void** args, uint32_t arg_count, uint32_t ring, uint32_t* pagedir);
 void     scheduler_init();
 void     schedule();
 void     scheduler_lock();

src/mm/page_tables.c

@@ -18,7 +18,7 @@ uint32_t get_pte(void *virtualaddr) {
 }
 
 static uint32_t next_user_virt = 0x00400000;
-void* setup_user_process(void* user_code_phys, uint32_t* user_stack_top) {
+void* setup_user_process(uint32_t* pd, void* user_code_phys, uint32_t* user_stack_top) {
     if ((uint32_t)user_code_phys & 0xFFF) {
         printf("SETUP_USER_PROCESS ERROR: user_code_phys not aligned\n");
         return 0;
@@ -36,12 +36,12 @@ void* setup_user_process(void* user_code_phys, uint32_t* user_stack_top) {
         return 0;
     }
 
-    unmap_page((void*)code_virt);
+    //unmap_page((void*)code_virt);
-    unmap_page((void*)stack_virt);
+    //unmap_page((void*)stack_virt);
 
 
-    map_page(user_code_phys, (void*)code_virt, 0x7);
+    map_page_in_directory(pd, user_code_phys, (void*)code_virt, 0x7);
-    map_page(stack_phys, (void*)stack_virt, 0x7);
+    map_page_in_directory(pd, stack_phys, (void*)stack_virt, 0x7);
     
     // Verify mappings
     uint32_t code_pte = get_pte((void*)code_virt);
@@ -140,6 +140,61 @@ void unmap_page(void *virtualaddr) {
     }
 }
 
+/**
+ * Maps a physical page to a virtual address in a SPECIFIED page directory.
+ * pd_virt_addr: Kernel virtual address of the target page directory table.
+ * phys_addr: Physical address of the page to map.
+ * virt_addr: Virtual address to map to.
+ * flags: PTE flags (e.g., PAGE_PRESENT | PAGE_USER | PAGE_RW).
+ * Returns 0 on success, -1 on failure.
+ */
+int map_page_in_directory(uint32_t* pd_virt_addr, void* phys_addr, void* virt_addr, uint32_t flags) {
+    uint32_t pde_idx = (uint32_t)virt_addr >> 22;
+    uint32_t pte_idx = ((uint32_t)virt_addr >> 12) & 0x3FF;
+
+    uint32_t pde = pd_virt_addr[pde_idx];
+    uint32_t* pt_virt_for_modification; // Virtual address of the page table to write PTEs into
+
+    if (!(pde & PAGE_PRESENT)) {
+        // Page table not present, need to allocate one
+        void* pt_phys_addr = alloc_page();
+        if (!pt_phys_addr) {
+            printf("map_page_in_directory: alloc_page failed for new page table (VA: %x)\n", (uint32_t)virt_addr);
+            return -1;
+        }
+
+        // Get a kernel virtual address for this new page table to initialize it
+        pt_virt_for_modification = (uint32_t*)phys_to_virt((uint32_t)pt_phys_addr);
+
+        // Temporarily map this new PT page into the *current* address space to zero it.
+        // This assumes map_page modifies the current CR3's address space.
+        map_page(pt_phys_addr, (void*)pt_virt_for_modification, PAGE_PRESENT | PAGE_RW); 
+        memset(pt_virt_for_modification, 0, PAGE_SIZE);
+        // Now, point the PDE in the target page directory (pd_virt_addr) to the new page table.
+        // The PDE stores the PHYSICAL address of the page table.
+        pd_virt_addr[pde_idx] = (uint32_t)pt_phys_addr | PAGE_PRESENT | PAGE_RW | PAGE_USER; // Ensure PAGE_USER if PTEs will have USER bit
+        // Note: If map_page for the PT itself isn't needed long-term in current PD, you might unmap it.
+        // However, if phys_to_virt gives a stable kernel mapping, this explicit map/unmap might be simplified.
+    } else {
+        // Page table already exists. Get its physical address from PDE, then its kernel virtual address.
+        pt_virt_for_modification = (uint32_t*)phys_to_virt(pde & ~0xFFF);
+        // This assumes that any existing page table pointed to by a PDE is already 
+        // accessible via its phys_to_virt address for modification.
+    }
+
+    // Set the PTE entry in this page table
+    // Ensure phys_addr is page-aligned; flags should not include low 12 bits of phys_addr
+    pt_virt_for_modification[pte_idx] = ((uint32_t)phys_addr & ~0xFFF) | (flags & 0xFFF);
+    
+    // When CR3 for the target task is loaded, TLB entries for virt_addr will be appropriately managed.
+    // If virt_addr was previously mapped by another process using this same PD (unlikely for new tasks),
+    // more complex TLB invalidation might be needed, but typically not for initial setup.
+    // invlpg may be needed here if you are re-mapping an address in a PD already in use by another CPU or
+    // if the PD is the current CR3 and the mapping changes. For setting up a new PD not yet in CR3, it's usually fine.
+
+    return 0; // Success
+}
+
 void map_kernel_page(void* virtualaddr, unsigned int flags) {
     uint32_t virt = (uint32_t)virtualaddr & ~0xFFF; // Выравниваем по 4 КБ
     if (virt < 0xC0000000) while(1); // Ошибка: ядро только выше 3 ГБ

src/tasking/task.c

@@ -22,7 +22,7 @@ extern Process* current;
 extern uint32_t pid_counter;
 extern uint32_t task_count;
 
-Process* task_create(uint32_t func, void** args, uint32_t arg_count, uint32_t ring)
+Process* task_create(uint32_t func, void** args, uint32_t arg_count, uint32_t ring, uint32_t* pagedir)
 {
     void *p_physical = alloc_page();
     Process* p = (Process*)((uint32_t)p_physical+0xC0000000);
@@ -56,6 +56,8 @@ Process* task_create(uint32_t func, void** args, uint32_t arg_count, uint32_t ri
     p->tf->eflags = FL_IF;
     p->tf->eip = (uint32_t)func;
 
+    p->page_directory = pagedir;//(uint32_t*)create_page_dir();
+
     if(ring == 3)
     {
         void* user_stack_physical = alloc_page();
@@ -63,7 +65,9 @@ Process* task_create(uint32_t func, void** args, uint32_t arg_count, uint32_t ri
         uint32_t user_stack_virtual_top = 0xBFFFF000 - ((p->pid -1) * (USTACKSIZE + 4096)); // Уникальный верх стека для каждого процесса
         uint32_t user_stack_virtual_base = user_stack_virtual_top - USTACKSIZE;
 
-        map_page(user_stack_physical, (void*)user_stack_virtual_base, PAGE_PRESENT | PAGE_RW | PAGE_USER); // Флаги 0x7
+        map_page_in_directory(p->page_directory, user_stack_physical, (void*)user_stack_virtual_base, PAGE_PRESENT | PAGE_RW | PAGE_USER); // Флаги 0x7
+
+        p->tf->usermode_esp = user_stack_virtual_top;
 
     }
 
@@ -74,8 +78,6 @@ Process* task_create(uint32_t func, void** args, uint32_t arg_count, uint32_t ri
     p->context->eip = (uint32_t)trapret;
     p->kesp = (uint32_t)sp;
 
-    p->page_directory = (uint32_t*)create_page_dir();
-
     p->next = 0;
 
     if (!queue) {
@@ -141,13 +143,15 @@ void jump_usermode2(void) ;
 
 void scheduler_init()
 {
-    task_create((uint32_t)idle, NULL, 0, 0);
+    uint32_t* kernel_tasks_pagedir = (uint32_t*)create_page_dir();
+
+    task_create((uint32_t)idle, NULL, 0, 0, kernel_tasks_pagedir);
 
     void* args1[] = {(void*)42, (void*)"ebalo"};
-    task_create((uint32_t)task1, args1, 2, 0);
+    task_create((uint32_t)task1, args1, 2, 0, kernel_tasks_pagedir);
     void* args2[] = {(void*)69, (void*)420};
-    task_create((uint32_t)task2, args2, 2, 0);
+    task_create((uint32_t)task2, args2, 2, 0, kernel_tasks_pagedir);
-	//jump_usermode2();
+	jump_usermode2();
 }
 
 #include "../include/string.h"
@@ -188,30 +192,16 @@ void jump_usermode2(void) {
     printf("Copied code to 0x%x (virt 0x%x)\n",
            (uint32_t)code_phys, kernel_temp_virt);
 
-    // Настраиваем Ring 3
+    uint32_t* proc_pd = (uint32_t*)create_page_dir();
-    uint32_t user_stack_top;
+    Process* p_task1 = task_create(0x400000, NULL, 0, 3, proc_pd);
-	uint32_t user_stack_top2;
+
-    void* user_code_virt = setup_user_process(code_phys, &user_stack_top);
+    if (map_page_in_directory(p_task1->page_directory, 
-    if (!user_code_virt) {
+        code_phys, 
-        printf("Failed to setup user process\n");
+        (void*)0x400000, 
-        while (1);
+        PAGE_PRESENT | PAGE_RW | PAGE_USER) != 0) { // PAGE_USER is critical, PAGE_RW for now, can be R-X
+
+        printf("jump_usermode2: Failed to map user code into task's PD for PID %d\n", p_task1->pid);
+        // TODO: Terminate/cleanup p_task1, free code_phys_task1
+        return;
     }
-
-	void *second_user_code_virt = setup_user_process(second_code_phys, &user_stack_top2);
-
-    printf("user_code_virt: 0x%x, user_stack_top: 0x%x\n",
-           (uint32_t)user_code_virt, user_stack_top);
-	
-	//map_page(alloc_page(), (void*)0x400000, 0x7);
-	map_page(alloc_page(), (void*)0x800000, 0x7);
-	map_page(alloc_page(), (void*)0x900000, 0x7);
-
-	uint32_t code_pte = get_pte(user_code_virt);
-	printf("Before iret: Code PTE at 0x%x: 0x%x (phys 0x%x, %s, %s)\n",
-       (uint32_t)user_code_virt, code_pte, code_pte & ~0xFFF,
-       (code_pte & 0x2) ? "writable" : "read-only",
-       (code_pte & 0x4) ? "user" : "supervisor");
-	
-	task_create((uint32_t)user_code_virt, NULL, 0, 3);
-	//task_create((uint32_t)second_user_code_virt, NULL, 0, 3);
 }