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/signal.h>
   8 #include <linux/sched.h>
   9 #include <linux/head.h>
  10 #include <linux/kernel.h>
  11 #include <linux/errno.h>
  12 #include <linux/string.h>
  13 #include <linux/types.h>
  14 #include <linux/ptrace.h>
  15 #include <linux/mman.h>
  16 #include <linux/mm.h>
  17 
  18 #include <asm/system.h>
  19 #include <asm/segment.h>
  20 #include <asm/pgtable.h>
  21 
  22 extern void die_if_kernel(char *,struct pt_regs *,long);
  23 
  24 /*
  25  * This routine handles page faults.  It determines the address,
  26  * and the problem, and then passes it off to handle_mm_fault().
  27  *
  28  * mmcsr:
  29  *      0 = translation not valid
  30  *      1 = access violation
  31  *      2 = fault-on-read
  32  *      3 = fault-on-execute
  33  *      4 = fault-on-write
  34  *
  35  * cause:
  36  *      -1 = instruction fetch
  37  *      0 = load
  38  *      1 = store
  39  */
  40 asmlinkage void do_page_fault(unsigned long address, unsigned long mmcsr, long cause,
     /*  */
  41         unsigned long a3, unsigned long a4, unsigned long a5,
  42         struct pt_regs regs)
  43 {
  44         struct vm_area_struct * vma;
  45 
  46         vma = find_vma(current, address);
  47         if (!vma)
  48                 goto bad_area;
  49         if (vma->vm_start <= address)
  50                 goto good_area;
  51         if (!(vma->vm_flags & VM_GROWSDOWN))
  52                 goto bad_area;
  53         if (expand_stack(vma, address))
  54                 goto bad_area;
  55 /*
  56  * Ok, we have a good vm_area for this memory access, so
  57  * we can handle it..
  58  */
  59 good_area:
  60         if (cause < 0) {
  61                 if (!(vma->vm_flags & VM_EXEC))
  62                         goto bad_area;
  63         } else if (!cause) {
  64                 /* Allow reads even for write-only mappings */
  65                 if (!(vma->vm_flags & (VM_READ | VM_WRITE)))
  66                         goto bad_area;
  67         } else {
  68                 if (!(vma->vm_flags & VM_WRITE))
  69                         goto bad_area;
  70         }
  71         tbis(address);
  72         handle_mm_fault(vma, address, cause > 0);
  73         return;
  74 
  75 /*
  76  * Something tried to access memory that isn't in our memory map..
  77  * Fix it, but check if it's kernel or user first..
  78  */
  79 bad_area:
  80         if (user_mode(&regs)) {
  81                 printk("memory violation at pc=%08lx (%08lx)\n", regs.pc, address);
  82                 die_if_kernel("oops", &regs, cause);
  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 }

/* */