i386/MIT/course/src/git.lab/user/faultallocbad.c

   1 // test user-level fault handler -- alloc pages to fix faults
   2 // doesn't work because we sys_cputs instead of cprintf (exercise: why?)
   3
   4 #include <inc/lib.h>
   5
   6 void
   7 handler(struct UTrapframe *utf)
   8 {
   9         int r;
  10         void *addr = (void*)utf->utf_fault_va;
  11
  12         cprintf("fault %x\n", addr);
  13         if ((r = sys_page_alloc(0, ROUNDDOWN(addr, PGSIZE),
  14                                 PTE_P|PTE_U|PTE_W)) < 0)
  15                 panic("allocating at %x in page fault handler: %e", addr, r);
  16         snprintf((char*) addr, 100, "this string was faulted in at %x", addr);
  17 }
  18
  19 void
  20 umain(int argc, char **argv)
  21 {
  22         set_pgfault_handler(handler);
  23         sys_cputs((char*)0xDEADBEEF, 4);
  24 }