arch/parisc/mm/fault.c

   1 /* $Id: fault.c,v 1.5 2000/01/26 16:20:29 jsm Exp $
   2  *
   3  * This file is subject to the terms and conditions of the GNU General Public
   4  * License.  See the file "COPYING" in the main directory of this archive
   5  * for more details.
   6  *
   7  *
   8  * Copyright (C) 1995, 1996, 1997, 1998 by Ralf Baechle
   9  * Copyright 1999 SuSE GmbH (Philipp Rumpf, prumpf@tux.org)
  10  * Copyright 1999 Hewlett Packard Co.
  11  *
  12  */
  13
  14 #include <linux/mm.h>
  15 #include <linux/ptrace.h>
  16 #include <linux/sched.h>
  17 #include <linux/interrupt.h>
  18 #include <linux/module.h>
  19
  20 #include <asm/uaccess.h>
  21 #include <asm/traps.h>
  22
  23 #define PRINT_USER_FAULTS /* (turn this on if you want user faults to be */
  24                          /*  dumped to the console via printk)          */
  25
  26
  27 /* Defines for parisc_acctyp()  */
  28 #define READ            0
  29 #define WRITE           1
  30
  31 /* Various important other fields */
  32 #define bit22set(x)             (x & 0x00000200)
  33 #define bits23_25set(x)         (x & 0x000001c0)
  34 #define isGraphicsFlushRead(x)  ((x & 0xfc003fdf) == 0x04001a80)
  35                                 /* extended opcode is 0x6a */
  36
  37 #define BITSSET         0x1c0   /* for identifying LDCW */
  38
  39
  40 DEFINE_PER_CPU(struct exception_data, exception_data);
  41
  42 /*
  43  * parisc_acctyp(unsigned int inst) --
  44  *    Given a PA-RISC memory access instruction, determine if the
  45  *    the instruction would perform a memory read or memory write
  46  *    operation.
  47  *
  48  *    This function assumes that the given instruction is a memory access
  49  *    instruction (i.e. you should really only call it if you know that
  50  *    the instruction has generated some sort of a memory access fault).
  51  *
  52  * Returns:
  53  *   VM_READ  if read operation
  54  *   VM_WRITE if write operation
  55  *   VM_EXEC  if execute operation
  56  */
  57 static unsigned long
  58 parisc_acctyp(unsigned long code, unsigned int inst)
  59 {
  60         if (code == 6 || code == 16)
  61             return VM_EXEC;
  62
  63         switch (inst & 0xf0000000) {
  64         case 0x40000000: /* load */
  65         case 0x50000000: /* new load */
  66                 return VM_READ;
  67
  68         case 0x60000000: /* store */
  69         case 0x70000000: /* new store */
  70                 return VM_WRITE;
  71
  72         case 0x20000000: /* coproc */
  73         case 0x30000000: /* coproc2 */
  74                 if (bit22set(inst))
  75                         return VM_WRITE;
  76
  77         case 0x0: /* indexed/memory management */
  78                 if (bit22set(inst)) {
  79                         /*
  80                          * Check for the 'Graphics Flush Read' instruction.
  81                          * It resembles an FDC instruction, except for bits
  82                          * 20 and 21. Any combination other than zero will
  83                          * utilize the block mover functionality on some
  84                          * older PA-RISC platforms.  The case where a block
  85                          * move is performed from VM to graphics IO space
  86                          * should be treated as a READ.
  87                          *
  88                          * The significance of bits 20,21 in the FDC
  89                          * instruction is:
  90                          *
  91                          *   00  Flush data cache (normal instruction behavior)
  92                          *   01  Graphics flush write  (IO space -> VM)
  93                          *   10  Graphics flush read   (VM -> IO space)
  94                          *   11  Graphics flush read/write (VM <-> IO space)
  95                          */
  96                         if (isGraphicsFlushRead(inst))
  97                                 return VM_READ;
  98                         return VM_WRITE;
  99                 } else {
 100                         /*
 101                          * Check for LDCWX and LDCWS (semaphore instructions).
 102                          * If bits 23 through 25 are all 1's it is one of
 103                          * the above two instructions and is a write.
 104                          *
 105                          * Note: With the limited bits we are looking at,
 106                          * this will also catch PROBEW and PROBEWI. However,
 107                          * these should never get in here because they don't
 108                          * generate exceptions of the type:
 109                          *   Data TLB miss fault/data page fault
 110                          *   Data memory protection trap
 111                          */
 112                         if (bits23_25set(inst) == BITSSET)
 113                                 return VM_WRITE;
 114                 }
 115                 return VM_READ; /* Default */
 116         }
 117         return VM_READ; /* Default */
 118 }
 119
 120 #undef bit22set
 121 #undef bits23_25set
 122 #undef isGraphicsFlushRead
 123 #undef BITSSET
 124
 125
 126 #if 0
 127 /* This is the treewalk to find a vma which is the highest that has
 128  * a start < addr.  We're using find_vma_prev instead right now, but
 129  * we might want to use this at some point in the future.  Probably
 130  * not, but I want it committed to CVS so I don't lose it :-)
 131  */
 132                         while (tree != vm_avl_empty) {
 133                                 if (tree->vm_start > addr) {
 134                                         tree = tree->vm_avl_left;
 135                                 } else {
 136                                         prev = tree;
 137                                         if (prev->vm_next == NULL)
 138                                                 break;
 139                                         if (prev->vm_next->vm_start > addr)
 140                                                 break;
 141                                         tree = tree->vm_avl_right;
 142                                 }
 143                         }
 144 #endif
 145
 146 void do_page_fault(struct pt_regs *regs, unsigned long code,
 147                               unsigned long address)
 148 {
 149         struct vm_area_struct *vma, *prev_vma;
 150         struct task_struct *tsk = current;
 151         struct mm_struct *mm = tsk->mm;
 152         const struct exception_table_entry *fix;
 153         unsigned long acc_type;
 154
 155         if (in_atomic() || !mm)
 156                 goto no_context;
 157
 158         down_read(&mm->mmap_sem);
 159         vma = find_vma_prev(mm, address, &prev_vma);
 160         if (!vma || address < vma->vm_start)
 161                 goto check_expansion;
 162 /*
 163  * Ok, we have a good vm_area for this memory access. We still need to
 164  * check the access permissions.
 165  */
 166
 167 good_area:
 168
 169         acc_type = parisc_acctyp(code,regs->iir);
 170
 171         if ((vma->vm_flags & acc_type) != acc_type)
 172                 goto bad_area;
 173
 174         /*
 175          * If for any reason at all we couldn't handle the fault, make
 176          * sure we exit gracefully rather than endlessly redo the
 177          * fault.
 178          */
 179
 180         switch (handle_mm_fault(mm, vma, address, (acc_type & VM_WRITE) != 0)) {
 181               case VM_FAULT_MINOR:
 182                 ++current->min_flt;
 183                 break;
 184               case VM_FAULT_MAJOR:
 185                 ++current->maj_flt;
 186                 break;
 187               case VM_FAULT_SIGBUS:
 188                 /*
 189                  * We hit a shared mapping outside of the file, or some
 190                  * other thing happened to us that made us unable to
 191                  * handle the page fault gracefully.
 192                  */
 193                 goto bad_area;
 194               default:
 195                 goto out_of_memory;
 196         }
 197         up_read(&mm->mmap_sem);
 198         return;
 199
 200 check_expansion:
 201         vma = prev_vma;
 202         if (vma && (expand_stack(vma, address) == 0))
 203                 goto good_area;
 204
 205 /*
 206  * Something tried to access memory that isn't in our memory map..
 207  */
 208 bad_area:
 209         up_read(&mm->mmap_sem);
 210
 211         if (user_mode(regs)) {
 212                 struct siginfo si;
 213
 214 #ifdef PRINT_USER_FAULTS
 215                 printk(KERN_DEBUG "\n");
 216                 printk(KERN_DEBUG "do_page_fault() pid=%d command='%s' type=%lu address=0x%08lx\n",
 217                     tsk->pid, tsk->comm, code, address);
 218                 if (vma) {
 219                         printk(KERN_DEBUG "vm_start = 0x%08lx, vm_end = 0x%08lx\n",
 220                                         vma->vm_start, vma->vm_end);
 221                 }
 222                 show_regs(regs);
 223 #endif
 224                 /* FIXME: actually we need to get the signo and code correct */
 225                 si.si_signo = SIGSEGV;
 226                 si.si_errno = 0;
 227                 si.si_code = SEGV_MAPERR;
 228                 si.si_addr = (void __user *) address;
 229                 force_sig_info(SIGSEGV, &si, current);
 230                 return;
 231         }
 232
 233 no_context:
 234
 235         if (!user_mode(regs)) {
 236                 fix = search_exception_tables(regs->iaoq[0]);
 237
 238                 if (fix) {
 239                         struct exception_data *d;
 240
 241                         d = &__get_cpu_var(exception_data);
 242                         d->fault_ip = regs->iaoq[0];
 243                         d->fault_space = regs->isr;
 244                         d->fault_addr = regs->ior;
 245
 246                         regs->iaoq[0] = ((fix->fixup) & ~3);
 247
 248                         /*
 249                          * NOTE: In some cases the faulting instruction
 250                          * may be in the delay slot of a branch. We
 251                          * don't want to take the branch, so we don't
 252                          * increment iaoq[1], instead we set it to be
 253                          * iaoq[0]+4, and clear the B bit in the PSW
 254                          */
 255
 256                         regs->iaoq[1] = regs->iaoq[0] + 4;
 257                         regs->gr[0] &= ~PSW_B; /* IPSW in gr[0] */
 258
 259                         return;
 260                 }
 261         }
 262
 263         parisc_terminate("Bad Address (null pointer deref?)", regs, code, address);
 264
 265   out_of_memory:
 266         up_read(&mm->mmap_sem);
 267         printk(KERN_CRIT "VM: killing process %s\n", current->comm);
 268         if (user_mode(regs))
 269                 do_exit(SIGKILL);
 270         goto no_context;
 271 }