arch/parisc/mm/fault.c

   1 /*
   2  * This file is subject to the terms and conditions of the GNU General Public
   3  * License.  See the file "COPYING" in the main directory of this archive
   4  * for more details.
   5  *
   6  *
   7  * Copyright (C) 1995, 1996, 1997, 1998 by Ralf Baechle
   8  * Copyright 1999 SuSE GmbH (Philipp Rumpf, prumpf@tux.org)
   9  * Copyright 1999 Hewlett Packard Co.
  10  *
  11  */
  12
  13 #include <linux/mm.h>
  14 #include <linux/ptrace.h>
  15 #include <linux/sched.h>
  16 #include <linux/interrupt.h>
  17 #include <linux/module.h>
  18 #include <linux/uaccess.h>
  19
  20 #include <asm/traps.h>
  21
  22 /* Various important other fields */
  23 #define bit22set(x)             (x & 0x00000200)
  24 #define bits23_25set(x)         (x & 0x000001c0)
  25 #define isGraphicsFlushRead(x)  ((x & 0xfc003fdf) == 0x04001a80)
  26                                 /* extended opcode is 0x6a */
  27
  28 #define BITSSET         0x1c0   /* for identifying LDCW */
  29
  30
  31 DEFINE_PER_CPU(struct exception_data, exception_data);
  32
  33 int show_unhandled_signals = 1;
  34
  35 /*
  36  * parisc_acctyp(unsigned int inst) --
  37  *    Given a PA-RISC memory access instruction, determine if the
  38  *    the instruction would perform a memory read or memory write
  39  *    operation.
  40  *
  41  *    This function assumes that the given instruction is a memory access
  42  *    instruction (i.e. you should really only call it if you know that
  43  *    the instruction has generated some sort of a memory access fault).
  44  *
  45  * Returns:
  46  *   VM_READ  if read operation
  47  *   VM_WRITE if write operation
  48  *   VM_EXEC  if execute operation
  49  */
  50 static unsigned long
  51 parisc_acctyp(unsigned long code, unsigned int inst)
  52 {
  53         if (code == 6 || code == 16)
  54             return VM_EXEC;
  55
  56         switch (inst & 0xf0000000) {
  57         case 0x40000000: /* load */
  58         case 0x50000000: /* new load */
  59                 return VM_READ;
  60
  61         case 0x60000000: /* store */
  62         case 0x70000000: /* new store */
  63                 return VM_WRITE;
  64
  65         case 0x20000000: /* coproc */
  66         case 0x30000000: /* coproc2 */
  67                 if (bit22set(inst))
  68                         return VM_WRITE;
  69
  70         case 0x0: /* indexed/memory management */
  71                 if (bit22set(inst)) {
  72                         /*
  73                          * Check for the 'Graphics Flush Read' instruction.
  74                          * It resembles an FDC instruction, except for bits
  75                          * 20 and 21. Any combination other than zero will
  76                          * utilize the block mover functionality on some
  77                          * older PA-RISC platforms.  The case where a block
  78                          * move is performed from VM to graphics IO space
  79                          * should be treated as a READ.
  80                          *
  81                          * The significance of bits 20,21 in the FDC
  82                          * instruction is:
  83                          *
  84                          *   00  Flush data cache (normal instruction behavior)
  85                          *   01  Graphics flush write  (IO space -> VM)
  86                          *   10  Graphics flush read   (VM -> IO space)
  87                          *   11  Graphics flush read/write (VM <-> IO space)
  88                          */
  89                         if (isGraphicsFlushRead(inst))
  90                                 return VM_READ;
  91                         return VM_WRITE;
  92                 } else {
  93                         /*
  94                          * Check for LDCWX and LDCWS (semaphore instructions).
  95                          * If bits 23 through 25 are all 1's it is one of
  96                          * the above two instructions and is a write.
  97                          *
  98                          * Note: With the limited bits we are looking at,
  99                          * this will also catch PROBEW and PROBEWI. However,
 100                          * these should never get in here because they don't
 101                          * generate exceptions of the type:
 102                          *   Data TLB miss fault/data page fault
 103                          *   Data memory protection trap
 104                          */
 105                         if (bits23_25set(inst) == BITSSET)
 106                                 return VM_WRITE;
 107                 }
 108                 return VM_READ; /* Default */
 109         }
 110         return VM_READ; /* Default */
 111 }
 112
 113 #undef bit22set
 114 #undef bits23_25set
 115 #undef isGraphicsFlushRead
 116 #undef BITSSET
 117
 118
 119 #if 0
 120 /* This is the treewalk to find a vma which is the highest that has
 121  * a start < addr.  We're using find_vma_prev instead right now, but
 122  * we might want to use this at some point in the future.  Probably
 123  * not, but I want it committed to CVS so I don't lose it :-)
 124  */
 125                         while (tree != vm_avl_empty) {
 126                                 if (tree->vm_start > addr) {
 127                                         tree = tree->vm_avl_left;
 128                                 } else {
 129                                         prev = tree;
 130                                         if (prev->vm_next == NULL)
 131                                                 break;
 132                                         if (prev->vm_next->vm_start > addr)
 133                                                 break;
 134                                         tree = tree->vm_avl_right;
 135                                 }
 136                         }
 137 #endif
 138
 139 int fixup_exception(struct pt_regs *regs)
 140 {
 141         const struct exception_table_entry *fix;
 142
 143         fix = search_exception_tables(regs->iaoq[0]);
 144         if (fix) {
 145                 struct exception_data *d;
 146                 d = this_cpu_ptr(&exception_data);
 147                 d->fault_ip = regs->iaoq[0];
 148                 d->fault_space = regs->isr;
 149                 d->fault_addr = regs->ior;
 150
 151                 regs->iaoq[0] = (unsigned long)&fix->fixup + fix->fixup;
 152                 regs->iaoq[0] &= ~3;
 153                 /*
 154                  * NOTE: In some cases the faulting instruction
 155                  * may be in the delay slot of a branch. We
 156                  * don't want to take the branch, so we don't
 157                  * increment iaoq[1], instead we set it to be
 158                  * iaoq[0]+4, and clear the B bit in the PSW
 159                  */
 160                 regs->iaoq[1] = regs->iaoq[0] + 4;
 161                 regs->gr[0] &= ~PSW_B; /* IPSW in gr[0] */
 162
 163                 return 1;
 164         }
 165
 166         return 0;
 167 }
 168
 169 /*
 170  * Print out info about fatal segfaults, if the show_unhandled_signals
 171  * sysctl is set:
 172  */
 173 static inline void
 174 show_signal_msg(struct pt_regs *regs, unsigned long code,
 175                 unsigned long address, struct task_struct *tsk,
 176                 struct vm_area_struct *vma)
 177 {
 178         if (!unhandled_signal(tsk, SIGSEGV))
 179                 return;
 180
 181         if (!printk_ratelimit())
 182                 return;
 183
 184         pr_warn("\n");
 185         pr_warn("do_page_fault() command='%s' type=%lu address=0x%08lx",
 186             tsk->comm, code, address);
 187         print_vma_addr(KERN_CONT " in ", regs->iaoq[0]);
 188         if (vma)
 189                 pr_warn(" vm_start = 0x%08lx, vm_end = 0x%08lx\n",
 190                                 vma->vm_start, vma->vm_end);
 191
 192         show_regs(regs);
 193 }
 194
 195 void do_page_fault(struct pt_regs *regs, unsigned long code,
 196                               unsigned long address)
 197 {
 198         struct vm_area_struct *vma, *prev_vma;
 199         struct task_struct *tsk;
 200         struct mm_struct *mm;
 201         unsigned long acc_type;
 202         int fault;
 203         unsigned int flags;
 204
 205         if (faulthandler_disabled())
 206                 goto no_context;
 207
 208         tsk = current;
 209         mm = tsk->mm;
 210         if (!mm)
 211                 goto no_context;
 212
 213         flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
 214         if (user_mode(regs))
 215                 flags |= FAULT_FLAG_USER;
 216
 217         acc_type = parisc_acctyp(code, regs->iir);
 218         if (acc_type & VM_WRITE)
 219                 flags |= FAULT_FLAG_WRITE;
 220 retry:
 221         down_read(&mm->mmap_sem);
 222         vma = find_vma_prev(mm, address, &prev_vma);
 223         if (!vma || address < vma->vm_start)
 224                 goto check_expansion;
 225 /*
 226  * Ok, we have a good vm_area for this memory access. We still need to
 227  * check the access permissions.
 228  */
 229
 230 good_area:
 231
 232         if ((vma->vm_flags & acc_type) != acc_type)
 233                 goto bad_area;
 234
 235         /*
 236          * If for any reason at all we couldn't handle the fault, make
 237          * sure we exit gracefully rather than endlessly redo the
 238          * fault.
 239          */
 240
 241         fault = handle_mm_fault(mm, vma, address, flags);
 242
 243         if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
 244                 return;
 245
 246         if (unlikely(fault & VM_FAULT_ERROR)) {
 247                 /*
 248                  * We hit a shared mapping outside of the file, or some
 249                  * other thing happened to us that made us unable to
 250                  * handle the page fault gracefully.
 251                  */
 252                 if (fault & VM_FAULT_OOM)
 253                         goto out_of_memory;
 254                 else if (fault & VM_FAULT_SIGSEGV)
 255                         goto bad_area;
 256                 else if (fault & VM_FAULT_SIGBUS)
 257                         goto bad_area;
 258                 BUG();
 259         }
 260         if (flags & FAULT_FLAG_ALLOW_RETRY) {
 261                 if (fault & VM_FAULT_MAJOR)
 262                         current->maj_flt++;
 263                 else
 264                         current->min_flt++;
 265                 if (fault & VM_FAULT_RETRY) {
 266                         flags &= ~FAULT_FLAG_ALLOW_RETRY;
 267
 268                         /*
 269                          * No need to up_read(&mm->mmap_sem) as we would
 270                          * have already released it in __lock_page_or_retry
 271                          * in mm/filemap.c.
 272                          */
 273
 274                         goto retry;
 275                 }
 276         }
 277         up_read(&mm->mmap_sem);
 278         return;
 279
 280 check_expansion:
 281         vma = prev_vma;
 282         if (vma && (expand_stack(vma, address) == 0))
 283                 goto good_area;
 284
 285 /*
 286  * Something tried to access memory that isn't in our memory map..
 287  */
 288 bad_area:
 289         up_read(&mm->mmap_sem);
 290
 291         if (user_mode(regs)) {
 292                 struct siginfo si;
 293
 294                 show_signal_msg(regs, code, address, tsk, vma);
 295
 296                 switch (code) {
 297                 case 15:        /* Data TLB miss fault/Data page fault */
 298                         /* send SIGSEGV when outside of vma */
 299                         if (!vma ||
 300                             address < vma->vm_start || address > vma->vm_end) {
 301                                 si.si_signo = SIGSEGV;
 302                                 si.si_code = SEGV_MAPERR;
 303                                 break;
 304                         }
 305
 306                         /* send SIGSEGV for wrong permissions */
 307                         if ((vma->vm_flags & acc_type) != acc_type) {
 308                                 si.si_signo = SIGSEGV;
 309                                 si.si_code = SEGV_ACCERR;
 310                                 break;
 311                         }
 312
 313                         /* probably address is outside of mapped file */
 314                         /* fall through */
 315                 case 17:        /* NA data TLB miss / page fault */
 316                 case 18:        /* Unaligned access - PCXS only */
 317                         si.si_signo = SIGBUS;
 318                         si.si_code = (code == 18) ? BUS_ADRALN : BUS_ADRERR;
 319                         break;
 320                 case 16:        /* Non-access instruction TLB miss fault */
 321                 case 26:        /* PCXL: Data memory access rights trap */
 322                 default:
 323                         si.si_signo = SIGSEGV;
 324                         si.si_code = (code == 26) ? SEGV_ACCERR : SEGV_MAPERR;
 325                         break;
 326                 }
 327                 si.si_errno = 0;
 328                 si.si_addr = (void __user *) address;
 329                 force_sig_info(si.si_signo, &si, current);
 330                 return;
 331         }
 332
 333 no_context:
 334
 335         if (!user_mode(regs) && fixup_exception(regs)) {
 336                 return;
 337         }
 338
 339         parisc_terminate("Bad Address (null pointer deref?)", regs, code, address);
 340
 341   out_of_memory:
 342         up_read(&mm->mmap_sem);
 343         if (!user_mode(regs))
 344                 goto no_context;
 345         pagefault_out_of_memory();
 346 }