i386/standford/2004/src/lab5/lib/pgfault.c

   1 // User-level page fault handler support.
   2 // We use an assembly language wrapper around a C function.
   3 // The assembly wrapper is in pfentry.S.
   4
   5 #include <inc/lib.h>
   6
   7
   8 // Assembly language pgfault entrypoint defined in lib/pgfaultentry.S.
   9 extern void _pgfault_entry(void);
  10
  11 // Pointer to currently installed C-language pgfault handler.
  12 void (*_pgfault_handler)(u_int, u_int);
  13
  14 //
  15 // Set the page fault handler function.
  16 // If there isn't one yet, _pgfault_handler will be 0.
  17 // The first time we register a handler, we need to
  18 // allocate an exception stack and tell the kernel to
  19 // call _asm_pgfault_handler on it.
  20 //
  21 void
  22 set_pgfault_handler(void (*fn)(u_int va, u_int err))
  23 {
  24         int r;
  25
  26         if (_pgfault_handler == 0) {
  27                 // Your code here:
  28                 // map one page of exception stack with top at UXSTACKTOP
  29                 // register assembly pgfault entrypoint with JOS kernel
  30                 panic("set_pgfault_handler not implemented");
  31         }
  32
  33         // Save handler pointer for assembly to call.
  34         _pgfault_handler = fn;
  35 }
  36