ptos/amd64: ps: Add support for CPL 3 processes

Signed-off-by: Chloe M <chloe@mensia.org>

service/ptos/arch/amd64/ps/thread.c

@@ -9,6 +9,7 @@
 #include <hal/thread.h>
 #include <hal/page.h>
 #include <ps/thread.h>
+#include <ps/process.h>
 #include <machine/gdt.h>
 #include <machine/lapic.h>
 #include <mm/vm.h>
@@ -44,16 +45,25 @@ static PT_STATUS
 ThreadInitTcb(THREAD *Thread, TCB *Tcb, UPTR Ip)
 {
     TRAP_FRAME *Frame;
+    PROCESS *Parent;
 
     if (Thread == NULL || Tcb == NULL) {
         return STATUS_INVALID_PARAM;
     }
 
+    Parent = Thread->Parent;
     Thread->StackBase = (UPTR)ThreadAllocKStack();
     if (Thread->StackBase == 0) {
         return STATUS_NO_MEMORY;
     }
 
+    Tcb->KStackLength = PAGESIZE;
+    Tcb->KStackBase = (UPTR)ThreadAllocKStack();
+    if (Tcb->KStackBase == 0) {
+        /* TODO: Free Thread->StackBase */
+        return STATUS_NO_MEMORY;
+    }
+
     /* Zero the whole frame */
     Frame = &Tcb->FrameSnapshot;
     RtlMemSet(Frame, 0, sizeof(*Frame));
@@ -62,8 +72,12 @@ ThreadInitTcb(THREAD *Thread, TCB *Tcb, UPTR Ip)
     Frame->Rflags = 0x202;
     Frame->Rsp = Thread->StackBase + PAGESIZE;
     Frame->Rip = Ip;
-    Frame->CodeSeg = GDT_KCODE;
-    Frame->StackSeg = GDT_KDATA;
+    Frame->CodeSeg = ISSET(Parent->Flags, PS_USER)
+        ? GDT_UCODE | 3
+        : GDT_KCODE;
+    Frame->StackSeg = ISSET(Parent->Flags, PS_USER)
+        ? GDT_UDATA | 3
+        : GDT_KDATA;
     return STATUS_SUCCESS;
 }