tasking: fix stack corruption on the scheduler trigger

include/task.h

@@ -68,6 +68,8 @@ typedef struct Process
     l9660_dir* cwd;
 
     void* brk;
+
+    uint32_t kstack_top;
 } Process;
 
 extern Process* current;

src/tasking/task.c

@@ -32,6 +32,9 @@ Process* task_create(uint32_t func, uint32_t user_esp, uint32_t ring, uint32_t*
     p->kstack = (char*)((uint32_t)kstack_physical+0xC0000000);
     map_page(kstack_physical, p->kstack, PAGE_PRESENT | PAGE_RW);
     debug_log("kstack: %X!!!!!!!!!!!!\n", p->kstack);
+
+    p->kstack_top = (uint32_t)p->kstack + KSTACKSIZE;
+
     uint8_t* sp = (uint8_t*)(p->kstack + KSTACKSIZE);
 
     sp -= sizeof(TrapFrame);
@@ -146,7 +149,7 @@ void schedule() {
     }
 
     if (next && next != current) {
-        tss.esp0 = next->kesp;
+        tss.esp0 = next->kstack_top;
         switchProcess(next);
     }