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/sched/debug.h>
  17 #include <linux/interrupt.h>
  18 #include <linux/extable.h>
  19 #include <linux/uaccess.h>
  20
  21 #include <asm/traps.h>
  22
  23 /* Various important other fields */
  24 #define bit22set(x)             (x & 0x00000200)
  25 #define bits23_25set(x)         (x & 0x000001c0)
  26 #define isGraphicsFlushRead(x)  ((x & 0xfc003fdf) == 0x04001a80)
  27                                 /* extended opcode is 0x6a */
  28
  29 #define BITSSET         0x1c0   /* for identifying LDCW */
  30
  31
  32 DEFINE_PER_CPU(struct exception_data, exception_data);
  33
  34 int show_unhandled_signals = 1;
  35
  36 /*
  37  * parisc_acctyp(unsigned int inst) --
  38  *    Given a PA-RISC memory access instruction, determine if the
  39  *    the instruction would perform a memory read or memory write
  40  *    operation.
  41  *
  42  *    This function assumes that the given instruction is a memory access
  43  *    instruction (i.e. you should really only call it if you know that
  44  *    the instruction has generated some sort of a memory access fault).
  45  *
  46  * Returns:
  47  *   VM_READ  if read operation
  48  *   VM_WRITE if write operation
  49  *   VM_EXEC  if execute operation
  50  */
  51 static unsigned long
  52 parisc_acctyp(unsigned long code, unsigned int inst)
  53 {
  54         if (code == 6 || code == 16)
  55             return VM_EXEC;
  56
  57         switch (inst & 0xf0000000) {
  58         case 0x40000000: /* load */
  59         case 0x50000000: /* new load */
  60                 return VM_READ;
  61
  62         case 0x60000000: /* store */
  63         case 0x70000000: /* new store */
  64                 return VM_WRITE;
  65
  66         case 0x20000000: /* coproc */
  67         case 0x30000000: /* coproc2 */
  68                 if (bit22set(inst))
  69                         return VM_WRITE;
  70
  71         case 0x0: /* indexed/memory management */
  72                 if (bit22set(inst)) {
  73                         /*
  74                          * Check for the 'Graphics Flush Read' instruction.
  75                          * It resembles an FDC instruction, except for bits
  76                          * 20 and 21. Any combination other than zero will
  77                          * utilize the block mover functionality on some
  78                          * older PA-RISC platforms.  The case where a block
  79                          * move is performed from VM to graphics IO space
  80                          * should be treated as a READ.
  81                          *
  82                          * The significance of bits 20,21 in the FDC
  83                          * instruction is:
  84                          *
  85                          *   00  Flush data cache (normal instruction behavior)
  86                          *   01  Graphics flush write  (IO space -> VM)
  87                          *   10  Graphics flush read   (VM -> IO space)
  88                          *   11  Graphics flush read/write (VM <-> IO space)
  89                          */
  90                         if (isGraphicsFlushRead(inst))
  91                                 return VM_READ;
  92                         return VM_WRITE;
  93                 } else {
  94                         /*
  95                          * Check for LDCWX and LDCWS (semaphore instructions).
  96                          * If bits 23 through 25 are all 1's it is one of
  97                          * the above two instructions and is a write.
  98                          *
  99                          * Note: With the limited bits we are looking at,
 100                          * this will also catch PROBEW and PROBEWI. However,
 101                          * these should never get in here because they don't
 102                          * generate exceptions of the type:
 103                          *   Data TLB miss fault/data page fault
 104                          *   Data memory protection trap
 105                          */
 106                         if (bits23_25set(inst) == BITSSET)
 107                                 return VM_WRITE;
 108                 }
 109                 return VM_READ; /* Default */
 110         }
 111         return VM_READ; /* Default */
 112 }
 113
 114 #undef bit22set
 115 #undef bits23_25set
 116 #undef isGraphicsFlushRead
 117 #undef BITSSET
 118
 119
 120 #if 0
 121 /* This is the treewalk to find a vma which is the highest that has
 122  * a start < addr.  We're using find_vma_prev instead right now, but
 123  * we might want to use this at some point in the future.  Probably
 124  * not, but I want it committed to CVS so I don't lose it :-)
 125  */
 126                         while (tree != vm_avl_empty) {
 127                                 if (tree->vm_start > addr) {
 128                                         tree = tree->vm_avl_left;
 129                                 } else {
 130                                         prev = tree;
 131                                         if (prev->vm_next == NULL)
 132                                                 break;
 133                                         if (prev->vm_next->vm_start > addr)
 134                                                 break;
 135                                         tree = tree->vm_avl_right;
 136                                 }
 137                         }
 138 #endif
 139
 140 int fixup_exception(struct pt_regs *regs)
 141 {
 142         const struct exception_table_entry *fix;
 143
 144         fix = search_exception_tables(regs->iaoq[0]);
 145         if (fix) {
 146                 struct exception_data *d;
 147                 d = this_cpu_ptr(&exception_data);
 148                 d->fault_ip = regs->iaoq[0];
 149                 d->fault_gp = regs->gr[27];
 150                 d->fault_space = regs->isr;
 151                 d->fault_addr = regs->ior;
 152
 153                 /*
 154                  * Fix up get_user() and put_user().
 155                  * ASM_EXCEPTIONTABLE_ENTRY_EFAULT() sets the least-significant
 156                  * bit in the relative address of the fixup routine to indicate
 157                  * that %r8 should be loaded with -EFAULT to report a userspace
 158                  * access error.
 159                  */
 160                 if (fix->fixup & 1) {
 161                         regs->gr[8] = -EFAULT;
 162
 163                         /* zero target register for get_user() */
 164                         if (parisc_acctyp(0, regs->iir) == VM_READ) {
 165                                 int treg = regs->iir & 0x1f;
 166                                 regs->gr[treg] = 0;
 167                         }
 168                 }
 169
 170                 regs->iaoq[0] = (unsigned long)&fix->fixup + fix->fixup;
 171                 regs->iaoq[0] &= ~3;
 172                 /*
 173                  * NOTE: In some cases the faulting instruction
 174                  * may be in the delay slot of a branch. We
 175                  * don't want to take the branch, so we don't
 176                  * increment iaoq[1], instead we set it to be
 177                  * iaoq[0]+4, and clear the B bit in the PSW
 178                  */
 179                 regs->iaoq[1] = regs->iaoq[0] + 4;
 180                 regs->gr[0] &= ~PSW_B; /* IPSW in gr[0] */
 181
 182                 return 1;
 183         }
 184
 185         return 0;
 186 }
 187
 188 /*
 189  * parisc hardware trap list
 190  *
 191  * Documented in section 3 "Addressing and Access Control" of the
 192  * "PA-RISC 1.1 Architecture and Instruction Set Reference Manual"
 193  * https://parisc.wiki.kernel.org/index.php/File:Pa11_acd.pdf
 194  *
 195  * For implementation see handle_interruption() in traps.c
 196  */
 197 static const char * const trap_description[] = {
 198         [1] "High-priority machine check (HPMC)",
 199         [2] "Power failure interrupt",
 200         [3] "Recovery counter trap",
 201         [5] "Low-priority machine check",
 202         [6] "Instruction TLB miss fault",
 203         [7] "Instruction access rights / protection trap",
 204         [8] "Illegal instruction trap",
 205         [9] "Break instruction trap",
 206         [10] "Privileged operation trap",
 207         [11] "Privileged register trap",
 208         [12] "Overflow trap",
 209         [13] "Conditional trap",
 210         [14] "FP Assist Exception trap",
 211         [15] "Data TLB miss fault",
 212         [16] "Non-access ITLB miss fault",
 213         [17] "Non-access DTLB miss fault",
 214         [18] "Data memory protection/unaligned access trap",
 215         [19] "Data memory break trap",
 216         [20] "TLB dirty bit trap",
 217         [21] "Page reference trap",
 218         [22] "Assist emulation trap",
 219         [25] "Taken branch trap",
 220         [26] "Data memory access rights trap",
 221         [27] "Data memory protection ID trap",
 222         [28] "Unaligned data reference trap",
 223 };
 224
 225 const char *trap_name(unsigned long code)
 226 {
 227         const char *t = NULL;
 228
 229         if (code < ARRAY_SIZE(trap_description))
 230                 t = trap_description[code];
 231
 232         return t ? t : "Unknown trap";
 233 }
 234
 235 /*
 236  * Print out info about fatal segfaults, if the show_unhandled_signals
 237  * sysctl is set:
 238  */
 239 static inline void
 240 show_signal_msg(struct pt_regs *regs, unsigned long code,
 241                 unsigned long address, struct task_struct *tsk,
 242                 struct vm_area_struct *vma)
 243 {
 244         if (!unhandled_signal(tsk, SIGSEGV))
 245                 return;
 246
 247         if (!printk_ratelimit())
 248                 return;
 249
 250         pr_warn("\n");
 251         pr_warn("do_page_fault() command='%s' type=%lu address=0x%08lx",
 252             tsk->comm, code, address);
 253         print_vma_addr(KERN_CONT " in ", regs->iaoq[0]);
 254
 255         pr_cont("\ntrap #%lu: %s%c", code, trap_name(code),
 256                 vma ? ',':'\n');
 257
 258         if (vma)
 259                 pr_cont(" vm_start = 0x%08lx, vm_end = 0x%08lx\n",
 260                         vma->vm_start, vma->vm_end);
 261
 262         show_regs(regs);
 263 }
 264
 265 void do_page_fault(struct pt_regs *regs, unsigned long code,
 266                               unsigned long address)
 267 {
 268         struct vm_area_struct *vma, *prev_vma;
 269         struct task_struct *tsk;
 270         struct mm_struct *mm;
 271         unsigned long acc_type;
 272         int fault;
 273         unsigned int flags;
 274
 275         if (faulthandler_disabled())
 276                 goto no_context;
 277
 278         tsk = current;
 279         mm = tsk->mm;
 280         if (!mm)
 281                 goto no_context;
 282
 283         flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
 284         if (user_mode(regs))
 285                 flags |= FAULT_FLAG_USER;
 286
 287         acc_type = parisc_acctyp(code, regs->iir);
 288         if (acc_type & VM_WRITE)
 289                 flags |= FAULT_FLAG_WRITE;
 290 retry:
 291         down_read(&mm->mmap_sem);
 292         vma = find_vma_prev(mm, address, &prev_vma);
 293         if (!vma || address < vma->vm_start)
 294                 goto check_expansion;
 295 /*
 296  * Ok, we have a good vm_area for this memory access. We still need to
 297  * check the access permissions.
 298  */
 299
 300 good_area:
 301
 302         if ((vma->vm_flags & acc_type) != acc_type)
 303                 goto bad_area;
 304
 305         /*
 306          * If for any reason at all we couldn't handle the fault, make
 307          * sure we exit gracefully rather than endlessly redo the
 308          * fault.
 309          */
 310
 311         fault = handle_mm_fault(vma, address, flags);
 312
 313         if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
 314                 return;
 315
 316         if (unlikely(fault & VM_FAULT_ERROR)) {
 317                 /*
 318                  * We hit a shared mapping outside of the file, or some
 319                  * other thing happened to us that made us unable to
 320                  * handle the page fault gracefully.
 321                  */
 322                 if (fault & VM_FAULT_OOM)
 323                         goto out_of_memory;
 324                 else if (fault & VM_FAULT_SIGSEGV)
 325                         goto bad_area;
 326                 else if (fault & VM_FAULT_SIGBUS)
 327                         goto bad_area;
 328                 BUG();
 329         }
 330         if (flags & FAULT_FLAG_ALLOW_RETRY) {
 331                 if (fault & VM_FAULT_MAJOR)
 332                         current->maj_flt++;
 333                 else
 334                         current->min_flt++;
 335                 if (fault & VM_FAULT_RETRY) {
 336                         flags &= ~FAULT_FLAG_ALLOW_RETRY;
 337
 338                         /*
 339                          * No need to up_read(&mm->mmap_sem) as we would
 340                          * have already released it in __lock_page_or_retry
 341                          * in mm/filemap.c.
 342                          */
 343
 344                         goto retry;
 345                 }
 346         }
 347         up_read(&mm->mmap_sem);
 348         return;
 349
 350 check_expansion:
 351         vma = prev_vma;
 352         if (vma && (expand_stack(vma, address) == 0))
 353                 goto good_area;
 354
 355 /*
 356  * Something tried to access memory that isn't in our memory map..
 357  */
 358 bad_area:
 359         up_read(&mm->mmap_sem);
 360
 361         if (user_mode(regs)) {
 362                 struct siginfo si;
 363
 364                 show_signal_msg(regs, code, address, tsk, vma);
 365
 366                 switch (code) {
 367                 case 15:        /* Data TLB miss fault/Data page fault */
 368                         /* send SIGSEGV when outside of vma */
 369                         if (!vma ||
 370                             address < vma->vm_start || address > vma->vm_end) {
 371                                 si.si_signo = SIGSEGV;
 372                                 si.si_code = SEGV_MAPERR;
 373                                 break;
 374                         }
 375
 376                         /* send SIGSEGV for wrong permissions */
 377                         if ((vma->vm_flags & acc_type) != acc_type) {
 378                                 si.si_signo = SIGSEGV;
 379                                 si.si_code = SEGV_ACCERR;
 380                                 break;
 381                         }
 382
 383                         /* probably address is outside of mapped file */
 384                         /* fall through */
 385                 case 17:        /* NA data TLB miss / page fault */
 386                 case 18:        /* Unaligned access - PCXS only */
 387                         si.si_signo = SIGBUS;
 388                         si.si_code = (code == 18) ? BUS_ADRALN : BUS_ADRERR;
 389                         break;
 390                 case 16:        /* Non-access instruction TLB miss fault */
 391                 case 26:        /* PCXL: Data memory access rights trap */
 392                 default:
 393                         si.si_signo = SIGSEGV;
 394                         si.si_code = (code == 26) ? SEGV_ACCERR : SEGV_MAPERR;
 395                         break;
 396                 }
 397                 si.si_errno = 0;
 398                 si.si_addr = (void __user *) address;
 399                 force_sig_info(si.si_signo, &si, current);
 400                 return;
 401         }
 402
 403 no_context:
 404
 405         if (!user_mode(regs) && fixup_exception(regs)) {
 406                 return;
 407         }
 408
 409         parisc_terminate("Bad Address (null pointer deref?)", regs, code, address);
 410
 411   out_of_memory:
 412         up_read(&mm->mmap_sem);
 413         if (!user_mode(regs))
 414                 goto no_context;
 415         pagefault_out_of_memory();
 416 }