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 #include <linux/hugetlb.h>
  21
  22 #include <asm/traps.h>
  23
  24 /* Various important other fields */
  25 #define bit22set(x)             (x & 0x00000200)
  26 #define bits23_25set(x)         (x & 0x000001c0)
  27 #define isGraphicsFlushRead(x)  ((x & 0xfc003fdf) == 0x04001a80)
  28                                 /* extended opcode is 0x6a */
  29
  30 #define BITSSET         0x1c0   /* for identifying LDCW */
  31
  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                 /* fall through */
  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                 /*
 147                  * Fix up get_user() and put_user().
 148                  * ASM_EXCEPTIONTABLE_ENTRY_EFAULT() sets the least-significant
 149                  * bit in the relative address of the fixup routine to indicate
 150                  * that %r8 should be loaded with -EFAULT to report a userspace
 151                  * access error.
 152                  */
 153                 if (fix->fixup & 1) {
 154                         regs->gr[8] = -EFAULT;
 155
 156                         /* zero target register for get_user() */
 157                         if (parisc_acctyp(0, regs->iir) == VM_READ) {
 158                                 int treg = regs->iir & 0x1f;
 159                                 BUG_ON(treg == 0);
 160                                 regs->gr[treg] = 0;
 161                         }
 162                 }
 163
 164                 regs->iaoq[0] = (unsigned long)&fix->fixup + fix->fixup;
 165                 regs->iaoq[0] &= ~3;
 166                 /*
 167                  * NOTE: In some cases the faulting instruction
 168                  * may be in the delay slot of a branch. We
 169                  * don't want to take the branch, so we don't
 170                  * increment iaoq[1], instead we set it to be
 171                  * iaoq[0]+4, and clear the B bit in the PSW
 172                  */
 173                 regs->iaoq[1] = regs->iaoq[0] + 4;
 174                 regs->gr[0] &= ~PSW_B; /* IPSW in gr[0] */
 175
 176                 return 1;
 177         }
 178
 179         return 0;
 180 }
 181
 182 /*
 183  * parisc hardware trap list
 184  *
 185  * Documented in section 3 "Addressing and Access Control" of the
 186  * "PA-RISC 1.1 Architecture and Instruction Set Reference Manual"
 187  * https://parisc.wiki.kernel.org/index.php/File:Pa11_acd.pdf
 188  *
 189  * For implementation see handle_interruption() in traps.c
 190  */
 191 static const char * const trap_description[] = {
 192         [1] "High-priority machine check (HPMC)",
 193         [2] "Power failure interrupt",
 194         [3] "Recovery counter trap",
 195         [5] "Low-priority machine check",
 196         [6] "Instruction TLB miss fault",
 197         [7] "Instruction access rights / protection trap",
 198         [8] "Illegal instruction trap",
 199         [9] "Break instruction trap",
 200         [10] "Privileged operation trap",
 201         [11] "Privileged register trap",
 202         [12] "Overflow trap",
 203         [13] "Conditional trap",
 204         [14] "FP Assist Exception trap",
 205         [15] "Data TLB miss fault",
 206         [16] "Non-access ITLB miss fault",
 207         [17] "Non-access DTLB miss fault",
 208         [18] "Data memory protection/unaligned access trap",
 209         [19] "Data memory break trap",
 210         [20] "TLB dirty bit trap",
 211         [21] "Page reference trap",
 212         [22] "Assist emulation trap",
 213         [25] "Taken branch trap",
 214         [26] "Data memory access rights trap",
 215         [27] "Data memory protection ID trap",
 216         [28] "Unaligned data reference trap",
 217 };
 218
 219 const char *trap_name(unsigned long code)
 220 {
 221         const char *t = NULL;
 222
 223         if (code < ARRAY_SIZE(trap_description))
 224                 t = trap_description[code];
 225
 226         return t ? t : "Unknown trap";
 227 }
 228
 229 /*
 230  * Print out info about fatal segfaults, if the show_unhandled_signals
 231  * sysctl is set:
 232  */
 233 static inline void
 234 show_signal_msg(struct pt_regs *regs, unsigned long code,
 235                 unsigned long address, struct task_struct *tsk,
 236                 struct vm_area_struct *vma)
 237 {
 238         if (!unhandled_signal(tsk, SIGSEGV))
 239                 return;
 240
 241         if (!printk_ratelimit())
 242                 return;
 243
 244         pr_warn("\n");
 245         pr_warn("do_page_fault() command='%s' type=%lu address=0x%08lx",
 246             tsk->comm, code, address);
 247         print_vma_addr(KERN_CONT " in ", regs->iaoq[0]);
 248
 249         pr_cont("\ntrap #%lu: %s%c", code, trap_name(code),
 250                 vma ? ',':'\n');
 251
 252         if (vma)
 253                 pr_cont(" vm_start = 0x%08lx, vm_end = 0x%08lx\n",
 254                         vma->vm_start, vma->vm_end);
 255
 256         show_regs(regs);
 257 }
 258
 259 void do_page_fault(struct pt_regs *regs, unsigned long code,
 260                               unsigned long address)
 261 {
 262         struct vm_area_struct *vma, *prev_vma;
 263         struct task_struct *tsk;
 264         struct mm_struct *mm;
 265         unsigned long acc_type;
 266         vm_fault_t fault = 0;
 267         unsigned int flags;
 268
 269         if (faulthandler_disabled())
 270                 goto no_context;
 271
 272         tsk = current;
 273         mm = tsk->mm;
 274         if (!mm)
 275                 goto no_context;
 276
 277         flags = FAULT_FLAG_DEFAULT;
 278         if (user_mode(regs))
 279                 flags |= FAULT_FLAG_USER;
 280
 281         acc_type = parisc_acctyp(code, regs->iir);
 282         if (acc_type & VM_WRITE)
 283                 flags |= FAULT_FLAG_WRITE;
 284 retry:
 285         down_read(&mm->mmap_sem);
 286         vma = find_vma_prev(mm, address, &prev_vma);
 287         if (!vma || address < vma->vm_start)
 288                 goto check_expansion;
 289 /*
 290  * Ok, we have a good vm_area for this memory access. We still need to
 291  * check the access permissions.
 292  */
 293
 294 good_area:
 295
 296         if ((vma->vm_flags & acc_type) != acc_type)
 297                 goto bad_area;
 298
 299         /*
 300          * If for any reason at all we couldn't handle the fault, make
 301          * sure we exit gracefully rather than endlessly redo the
 302          * fault.
 303          */
 304
 305         fault = handle_mm_fault(vma, address, flags);
 306
 307         if (fault_signal_pending(fault, regs))
 308                 return;
 309
 310         if (unlikely(fault & VM_FAULT_ERROR)) {
 311                 /*
 312                  * We hit a shared mapping outside of the file, or some
 313                  * other thing happened to us that made us unable to
 314                  * handle the page fault gracefully.
 315                  */
 316                 if (fault & VM_FAULT_OOM)
 317                         goto out_of_memory;
 318                 else if (fault & VM_FAULT_SIGSEGV)
 319                         goto bad_area;
 320                 else if (fault & (VM_FAULT_SIGBUS|VM_FAULT_HWPOISON|
 321                                   VM_FAULT_HWPOISON_LARGE))
 322                         goto bad_area;
 323                 BUG();
 324         }
 325         if (flags & FAULT_FLAG_ALLOW_RETRY) {
 326                 if (fault & VM_FAULT_MAJOR)
 327                         current->maj_flt++;
 328                 else
 329                         current->min_flt++;
 330                 if (fault & VM_FAULT_RETRY) {
 331                         /*
 332                          * No need to up_read(&mm->mmap_sem) as we would
 333                          * have already released it in __lock_page_or_retry
 334                          * in mm/filemap.c.
 335                          */
 336                         flags |= FAULT_FLAG_TRIED;
 337                         goto retry;
 338                 }
 339         }
 340         up_read(&mm->mmap_sem);
 341         return;
 342
 343 check_expansion:
 344         vma = prev_vma;
 345         if (vma && (expand_stack(vma, address) == 0))
 346                 goto good_area;
 347
 348 /*
 349  * Something tried to access memory that isn't in our memory map..
 350  */
 351 bad_area:
 352         up_read(&mm->mmap_sem);
 353
 354         if (user_mode(regs)) {
 355                 int signo, si_code;
 356
 357                 switch (code) {
 358                 case 15:        /* Data TLB miss fault/Data page fault */
 359                         /* send SIGSEGV when outside of vma */
 360                         if (!vma ||
 361                             address < vma->vm_start || address >= vma->vm_end) {
 362                                 signo = SIGSEGV;
 363                                 si_code = SEGV_MAPERR;
 364                                 break;
 365                         }
 366
 367                         /* send SIGSEGV for wrong permissions */
 368                         if ((vma->vm_flags & acc_type) != acc_type) {
 369                                 signo = SIGSEGV;
 370                                 si_code = SEGV_ACCERR;
 371                                 break;
 372                         }
 373
 374                         /* probably address is outside of mapped file */
 375                         /* fall through */
 376                 case 17:        /* NA data TLB miss / page fault */
 377                 case 18:        /* Unaligned access - PCXS only */
 378                         signo = SIGBUS;
 379                         si_code = (code == 18) ? BUS_ADRALN : BUS_ADRERR;
 380                         break;
 381                 case 16:        /* Non-access instruction TLB miss fault */
 382                 case 26:        /* PCXL: Data memory access rights trap */
 383                 default:
 384                         signo = SIGSEGV;
 385                         si_code = (code == 26) ? SEGV_ACCERR : SEGV_MAPERR;
 386                         break;
 387                 }
 388 #ifdef CONFIG_MEMORY_FAILURE
 389                 if (fault & (VM_FAULT_HWPOISON|VM_FAULT_HWPOISON_LARGE)) {
 390                         unsigned int lsb = 0;
 391                         printk(KERN_ERR
 392         "MCE: Killing %s:%d due to hardware memory corruption fault at %08lx\n",
 393                         tsk->comm, tsk->pid, address);
 394                         /*
 395                          * Either small page or large page may be poisoned.
 396                          * In other words, VM_FAULT_HWPOISON_LARGE and
 397                          * VM_FAULT_HWPOISON are mutually exclusive.
 398                          */
 399                         if (fault & VM_FAULT_HWPOISON_LARGE)
 400                                 lsb = hstate_index_to_shift(VM_FAULT_GET_HINDEX(fault));
 401                         else if (fault & VM_FAULT_HWPOISON)
 402                                 lsb = PAGE_SHIFT;
 403
 404                         force_sig_mceerr(BUS_MCEERR_AR, (void __user *) address,
 405                                          lsb);
 406                         return;
 407                 }
 408 #endif
 409                 show_signal_msg(regs, code, address, tsk, vma);
 410
 411                 force_sig_fault(signo, si_code, (void __user *) address);
 412                 return;
 413         }
 414
 415 no_context:
 416
 417         if (!user_mode(regs) && fixup_exception(regs)) {
 418                 return;
 419         }
 420
 421         parisc_terminate("Bad Address (null pointer deref?)", regs, code, address);
 422
 423   out_of_memory:
 424         up_read(&mm->mmap_sem);
 425         if (!user_mode(regs))
 426                 goto no_context;
 427         pagefault_out_of_memory();
 428 }