arch/m68k/mm/fault.c

   1 /*
   2  *  linux/arch/m68k/mm/fault.c
   3  *
   4  *  Copyright (C) 1995  Hamish Macdonald
   5  */
   6
   7 #include <linux/mman.h>
   8 #include <linux/mm.h>
   9 #include <linux/kernel.h>
  10 #include <linux/ptrace.h>
  11 #include <linux/interrupt.h>
  12 #include <linux/module.h>
  13
  14 #include <asm/setup.h>
  15 #include <asm/traps.h>
  16 #include <asm/system.h>
  17 #include <asm/uaccess.h>
  18 #include <asm/pgalloc.h>
  19
  20 extern void die_if_kernel(char *, struct pt_regs *, long);
  21
  22 int send_fault_sig(struct pt_regs *regs)
  23 {
  24         siginfo_t siginfo = { 0, 0, 0, };
  25
  26         siginfo.si_signo = current->thread.signo;
  27         siginfo.si_code = current->thread.code;
  28         siginfo.si_addr = (void *)current->thread.faddr;
  29 #ifdef DEBUG
  30         printk("send_fault_sig: %p,%d,%d\n", siginfo.si_addr, siginfo.si_signo, siginfo.si_code);
  31 #endif
  32
  33         if (user_mode(regs)) {
  34                 force_sig_info(siginfo.si_signo,
  35                                &siginfo, current);
  36         } else {
  37                 if (handle_kernel_fault(regs))
  38                         return -1;
  39
  40                 //if (siginfo.si_signo == SIGBUS)
  41                 //      force_sig_info(siginfo.si_signo,
  42                 //                     &siginfo, current);
  43
  44                 /*
  45                  * Oops. The kernel tried to access some bad page. We'll have to
  46                  * terminate things with extreme prejudice.
  47                  */
  48                 if ((unsigned long)siginfo.si_addr < PAGE_SIZE)
  49                         printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference");
  50                 else
  51                         printk(KERN_ALERT "Unable to handle kernel access");
  52                 printk(" at virtual address %p\n", siginfo.si_addr);
  53                 die_if_kernel("Oops", regs, 0 /*error_code*/);
  54                 do_exit(SIGKILL);
  55         }
  56
  57         return 1;
  58 }
  59
  60 /*
  61  * This routine handles page faults.  It determines the problem, and
  62  * then passes it off to one of the appropriate routines.
  63  *
  64  * error_code:
  65  *      bit 0 == 0 means no page found, 1 means protection fault
  66  *      bit 1 == 0 means read, 1 means write
  67  *
  68  * If this routine detects a bad access, it returns 1, otherwise it
  69  * returns 0.
  70  */
  71 int do_page_fault(struct pt_regs *regs, unsigned long address,
  72                               unsigned long error_code)
  73 {
  74         struct mm_struct *mm = current->mm;
  75         struct vm_area_struct * vma;
  76         int write, fault;
  77
  78 #ifdef DEBUG
  79         printk ("do page fault:\nregs->sr=%#x, regs->pc=%#lx, address=%#lx, %ld, %p\n",
  80                 regs->sr, regs->pc, address, error_code,
  81                 current->mm->pgd);
  82 #endif
  83
  84         /*
  85          * If we're in an interrupt or have no user
  86          * context, we must not take the fault..
  87          */
  88         if (in_atomic() || !mm)
  89                 goto no_context;
  90
  91         down_read(&mm->mmap_sem);
  92
  93         vma = find_vma(mm, address);
  94         if (!vma)
  95                 goto map_err;
  96         if (vma->vm_flags & VM_IO)
  97                 goto acc_err;
  98         if (vma->vm_start <= address)
  99                 goto good_area;
 100         if (!(vma->vm_flags & VM_GROWSDOWN))
 101                 goto map_err;
 102         if (user_mode(regs)) {
 103                 /* Accessing the stack below usp is always a bug.  The
 104                    "+ 256" is there due to some instructions doing
 105                    pre-decrement on the stack and that doesn't show up
 106                    until later.  */
 107                 if (address + 256 < rdusp())
 108                         goto map_err;
 109         }
 110         if (expand_stack(vma, address))
 111                 goto map_err;
 112
 113 /*
 114  * Ok, we have a good vm_area for this memory access, so
 115  * we can handle it..
 116  */
 117 good_area:
 118 #ifdef DEBUG
 119         printk("do_page_fault: good_area\n");
 120 #endif
 121         write = 0;
 122         switch (error_code & 3) {
 123                 default:        /* 3: write, present */
 124                         /* fall through */
 125                 case 2:         /* write, not present */
 126                         if (!(vma->vm_flags & VM_WRITE))
 127                                 goto acc_err;
 128                         write++;
 129                         break;
 130                 case 1:         /* read, present */
 131                         goto acc_err;
 132                 case 0:         /* read, not present */
 133                         if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
 134                                 goto acc_err;
 135         }
 136
 137         /*
 138          * If for any reason at all we couldn't handle the fault,
 139          * make sure we exit gracefully rather than endlessly redo
 140          * the fault.
 141          */
 142
 143         fault = handle_mm_fault(mm, vma, address, write ? FAULT_FLAG_WRITE : 0);
 144 #ifdef DEBUG
 145         printk("handle_mm_fault returns %d\n",fault);
 146 #endif
 147         if (unlikely(fault & VM_FAULT_ERROR)) {
 148                 if (fault & VM_FAULT_OOM)
 149                         goto out_of_memory;
 150                 else if (fault & VM_FAULT_SIGSEGV)
 151                         goto map_err;
 152                 else if (fault & VM_FAULT_SIGBUS)
 153                         goto bus_err;
 154                 BUG();
 155         }
 156         if (fault & VM_FAULT_MAJOR)
 157                 current->maj_flt++;
 158         else
 159                 current->min_flt++;
 160
 161         up_read(&mm->mmap_sem);
 162         return 0;
 163
 164 /*
 165  * We ran out of memory, or some other thing happened to us that made
 166  * us unable to handle the page fault gracefully.
 167  */
 168 out_of_memory:
 169         up_read(&mm->mmap_sem);
 170         if (!user_mode(regs))
 171                 goto no_context;
 172         pagefault_out_of_memory();
 173         return 0;
 174
 175 no_context:
 176         current->thread.signo = SIGBUS;
 177         current->thread.faddr = address;
 178         return send_fault_sig(regs);
 179
 180 bus_err:
 181         current->thread.signo = SIGBUS;
 182         current->thread.code = BUS_ADRERR;
 183         current->thread.faddr = address;
 184         goto send_sig;
 185
 186 map_err:
 187         current->thread.signo = SIGSEGV;
 188         current->thread.code = SEGV_MAPERR;
 189         current->thread.faddr = address;
 190         goto send_sig;
 191
 192 acc_err:
 193         current->thread.signo = SIGSEGV;
 194         current->thread.code = SEGV_ACCERR;
 195         current->thread.faddr = address;
 196
 197 send_sig:
 198         up_read(&mm->mmap_sem);
 199         return send_fault_sig(regs);
 200 }