tasking: add simple base for running things in ring 3

src/mm/page_tables.c

@@ -1,6 +1,26 @@
 #include "../include/paging.h"
 #include <stdint.h>
 
+static uint32_t next_user_virt = 0x00400000;
+void* setup_user_process(void* user_code_phys, uint32_t* user_stack_top) {
+    void* stack_phys = alloc_page();
+    if (!stack_phys) return 0;
+
+    uint32_t code_virt = next_user_virt;
+    uint32_t stack_virt = code_virt + 0x3FF000; // 4 МБ - 4 КБ
+    map_page(user_code_phys, (void*)code_virt, 0x7);
+    map_page(stack_phys, (void*)stack_virt, 0x7);
+
+    *user_stack_top = stack_virt + 0x1000;
+    next_user_virt += 0x400000; // Следующий 4 МБ блок
+    return (void*)code_virt;
+}
+
+void free_user_process(void* code_phys, void* stack_phys) {
+    free_page(code_phys);
+    free_page(stack_phys);
+}
+
 void *get_physaddr(void *virtualaddr) {
     unsigned long pdindex = (unsigned long)virtualaddr >> 22;
     unsigned long ptindex = (unsigned long)virtualaddr >> 12 & 0x03FF;
@@ -85,4 +105,4 @@ void map_kernel_page(void* virtualaddr, unsigned int flags) {
 
     pt[ptindex] = (uint32_t)phys | (flags & 0xFFF) | 0x1; // supervisor, present
     asm volatile("invlpg (%0)" : : "r" (virtualaddr) : "memory");
-}
+}