feat: add Rust userspace support; fix TLS layout for p_align < 16; kill whole process on sibling-thread faults

kernel/src/Hal/IDT.cpp

@@ -177,7 +177,17 @@ namespace Hal {
                 if (i == 0x00) sig = 8;             /* #DE -> SIGFPE */
                 else if (i == 0x06) sig = 4;        /* #UD -> SIGILL */
                 else if (i == 0x10 || i == 0x13) sig = 8;  /* x87/SIMD FP */
-                Sched::SetProcessExitCode(proc->pid, 256 + sig);
+
+                // ExitProcess from a sibling thread ends only that thread,
+                // which would leave the process running with the crash
+                // swallowed. Flag the whole process (main thread and every
+                // sibling) first, carrying the crash code rather than
+                // KillProcess's default SIGKILL, so waiters see the fault.
+                if (Sched::GetCurrentThreadPtr() != proc) {
+                    Sched::KillProcess(proc->pid, 256 + sig);
+                } else {
+                    Sched::SetProcessExitCode(proc->pid, 256 + sig);
+                }
             }
 
             Sched::ExitProcess();