root/arch/alpha/mm/fault.c

/* */

DEFINITIONS

1. do_page_fault

   1 /*
   2  *  linux/arch/alpha/mm/fault.c
   3  *
   4  *  Copyright (C) 1995  Linus Torvalds
   5  */
   6 
   7 #include <linux/config.h>
   8 #include <linux/signal.h>
   9 #include <linux/sched.h>
  10 #include <linux/head.h>
  11 #include <linux/kernel.h>
  12 #include <linux/errno.h>
  13 #include <linux/string.h>
  14 #include <linux/types.h>
  15 #include <linux/ptrace.h>
  16 #include <linux/mman.h>
  17 #include <linux/mm.h>
  18 
  19 #include <asm/system.h>
  20 #include <asm/segment.h>
  21 #include <asm/pgtable.h>
  22 
  23 extern void die_if_kernel(char *,struct pt_regs *,long);
  24 
  25 /*
  26  * This routine handles page faults.  It determines the address,
  27  * and the problem, and then passes it off to handle_mm_fault().
  28  *
  29  * mmcsr:
  30  *      0 = translation not valid
  31  *      1 = access violation
  32  *      2 = fault-on-read
  33  *      3 = fault-on-execute
  34  *      4 = fault-on-write
  35  *
  36  * cause:
  37  *      -1 = instruction fetch
  38  *      0 = load
  39  *      1 = store
  40  */
  41 asmlinkage void do_page_fault(unsigned long address, unsigned long mmcsr, long cause,
     /*  */
  42         unsigned long a3, unsigned long a4, unsigned long a5,
  43         struct pt_regs regs)
  44 {
  45         struct vm_area_struct * vma;
  46 
  47         vma = find_vma(current, address);
  48         if (!vma)
  49                 goto bad_area;
  50         if (vma->vm_start <= address)
  51                 goto good_area;
  52         if (!(vma->vm_flags & VM_GROWSDOWN))
  53                 goto bad_area;
  54         if (vma->vm_end - address > current->rlim[RLIMIT_STACK].rlim_cur)
  55                 goto bad_area;
  56         vma->vm_offset -= vma->vm_start - (address & PAGE_MASK);
  57         vma->vm_start = (address & PAGE_MASK);
  58 /*
  59  * Ok, we have a good vm_area for this memory access, so
  60  * we can handle it..
  61  */
  62 good_area:
  63         if (cause < 0) {
  64                 if (!(vma->vm_flags & VM_EXEC))
  65                         goto bad_area;
  66         } else if (!cause) {
  67                 if (!(vma->vm_flags & VM_READ))
  68                         goto bad_area;
  69         } else {
  70                 if (!(vma->vm_flags & VM_WRITE))
  71                         goto bad_area;
  72         }
  73 
  74         handle_mm_fault(vma, address, cause > 0);
  75         return;
  76 
  77 /*
  78  * Something tried to access memory that isn't in our memory map..
  79  * Fix it, but check if it's kernel or user first..
  80  */
  81 bad_area:
  82         if (user_mode(&regs)) {
  83                 send_sig(SIGSEGV, current, 1);
  84                 return;
  85         }
  86 /*
  87  * Oops. The kernel tried to access some bad page. We'll have to
  88  * terminate things with extreme prejudice.
  89  */
  90         printk(KERN_ALERT "Unable to handle kernel paging request at virtual address %08lx\n",address);
  91         die_if_kernel("Oops", &regs, cause);
  92         do_exit(SIGKILL);
  93 }

/* */