LAB 4 IS DONE.

lab/user/faultbadhandler.c

@@ -0,0 +1,14 @@
+// test bad pointer for user-level fault handler
+// this is going to fault in the fault handler accessing eip (always!)
+// so eventually the kernel kills it (PFM_KILL) because
+// we outrun the stack with invocations of the user-level handler
+
+#include <inc/lib.h>
+
+void
+umain(int argc, char **argv)
+{
+	sys_page_alloc(0, (void*) (UXSTACKTOP - PGSIZE), PTE_P|PTE_U|PTE_W);
+	sys_env_set_pgfault_upcall(0, (void*) 0xDeadBeef);
+	*(int*)0 = 0;
+}