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 #include <linux/perf_event.h>
  22
  23 #include <asm/traps.h>
  24
  25 /* Various important other fields */
  26 #define bit22set(x)             (x & 0x00000200)
  27 #define bits23_25set(x)         (x & 0x000001c0)
  28 #define isGraphicsFlushRead(x)  ((x & 0xfc003fdf) == 0x04001a80)
  29                                 /* extended opcode is 0x6a */
  30
  31 #define BITSSET         0x1c0   /* for identifying LDCW */
  32
  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                 fallthrough;
  71
  72         case 0x0: /* indexed/memory management */
  73                 if (bit22set(inst)) {
  74                         /*
  75                          * Check for the 'Graphics Flush Read' instruction.
  76                          * It resembles an FDC instruction, except for bits
  77                          * 20 and 21. Any combination other than zero will
  78                          * utilize the block mover functionality on some
  79                          * older PA-RISC platforms.  The case where a block
  80                          * move is performed from VM to graphics IO space
  81                          * should be treated as a READ.
  82                          *
  83                          * The significance of bits 20,21 in the FDC
  84                          * instruction is:
  85                          *
  86                          *   00  Flush data cache (normal instruction behavior)
  87                          *   01  Graphics flush write  (IO space -> VM)
  88                          *   10  Graphics flush read   (VM -> IO space)
  89                          *   11  Graphics flush read/write (VM <-> IO space)
  90                          */
  91                         if (isGraphicsFlushRead(inst))
  92                                 return VM_READ;
  93                         return VM_WRITE;
  94                 } else {
  95                         /*
  96                          * Check for LDCWX and LDCWS (semaphore instructions).
  97                          * If bits 23 through 25 are all 1's it is one of
  98                          * the above two instructions and is a write.
  99                          *
 100                          * Note: With the limited bits we are looking at,
 101                          * this will also catch PROBEW and PROBEWI. However,
 102                          * these should never get in here because they don't
 103                          * generate exceptions of the type:
 104                          *   Data TLB miss fault/data page fault
 105                          *   Data memory protection trap
 106                          */
 107                         if (bits23_25set(inst) == BITSSET)
 108                                 return VM_WRITE;
 109                 }
 110                 return VM_READ; /* Default */
 111         }
 112         return VM_READ; /* Default */
 113 }
 114
 115 #undef bit22set
 116 #undef bits23_25set
 117 #undef isGraphicsFlushRead
 118 #undef BITSSET
 119
 120
 121 #if 0
 122 /* This is the treewalk to find a vma which is the highest that has
 123  * a start < addr.  We're using find_vma_prev instead right now, but
 124  * we might want to use this at some point in the future.  Probably
 125  * not, but I want it committed to CVS so I don't lose it :-)
 126  */
 127                         while (tree != vm_avl_empty) {
 128                                 if (tree->vm_start > addr) {
 129                                         tree = tree->vm_avl_left;
 130                                 } else {
 131                                         prev = tree;
 132                                         if (prev->vm_next == NULL)
 133                                                 break;
 134                                         if (prev->vm_next->vm_start > addr)
 135                                                 break;
 136                                         tree = tree->vm_avl_right;
 137                                 }
 138                         }
 139 #endif
 140
 141 int fixup_exception(struct pt_regs *regs)
 142 {
 143         const struct exception_table_entry *fix;
 144
 145         fix = search_exception_tables(regs->iaoq[0]);
 146         if (fix) {
 147                 /*
 148                  * Fix up get_user() and put_user().
 149                  * ASM_EXCEPTIONTABLE_ENTRY_EFAULT() sets the least-significant
 150                  * bit in the relative address of the fixup routine to indicate
 151                  * that %r8 should be loaded with -EFAULT to report a userspace
 152                  * access error.
 153                  */
 154                 if (fix->fixup & 1) {
 155                         regs->gr[8] = -EFAULT;
 156
 157                         /* zero target register for get_user() */
 158                         if (parisc_acctyp(0, regs->iir) == VM_READ) {
 159                                 int treg = regs->iir & 0x1f;
 160                                 BUG_ON(treg == 0);
 161                                 regs->gr[treg] = 0;
 162                         }
 163                 }
 164
 165                 regs->iaoq[0] = (unsigned long)&fix->fixup + fix->fixup;
 166                 regs->iaoq[0] &= ~3;
 167                 /*
 168                  * NOTE: In some cases the faulting instruction
 169                  * may be in the delay slot of a branch. We
 170                  * don't want to take the branch, so we don't
 171                  * increment iaoq[1], instead we set it to be
 172                  * iaoq[0]+4, and clear the B bit in the PSW
 173                  */
 174                 regs->iaoq[1] = regs->iaoq[0] + 4;
 175                 regs->gr[0] &= ~PSW_B; /* IPSW in gr[0] */
 176
 177                 return 1;
 178         }
 179
 180         return 0;
 181 }
 182
 183 /*
 184  * parisc hardware trap list
 185  *
 186  * Documented in section 3 "Addressing and Access Control" of the
 187  * "PA-RISC 1.1 Architecture and Instruction Set Reference Manual"
 188  * https://parisc.wiki.kernel.org/index.php/File:Pa11_acd.pdf
 189  *
 190  * For implementation see handle_interruption() in traps.c
 191  */
 192 static const char * const trap_description[] = {
 193         [1] "High-priority machine check (HPMC)",
 194         [2] "Power failure interrupt",
 195         [3] "Recovery counter trap",
 196         [5] "Low-priority machine check",
 197         [6] "Instruction TLB miss fault",
 198         [7] "Instruction access rights / protection trap",
 199         [8] "Illegal instruction trap",
 200         [9] "Break instruction trap",
 201         [10] "Privileged operation trap",
 202         [11] "Privileged register trap",
 203         [12] "Overflow trap",
 204         [13] "Conditional trap",
 205         [14] "FP Assist Exception trap",
 206         [15] "Data TLB miss fault",
 207         [16] "Non-access ITLB miss fault",
 208         [17] "Non-access DTLB miss fault",
 209         [18] "Data memory protection/unaligned access trap",
 210         [19] "Data memory break trap",
 211         [20] "TLB dirty bit trap",
 212         [21] "Page reference trap",
 213         [22] "Assist emulation trap",
 214         [25] "Taken branch trap",
 215         [26] "Data memory access rights trap",
 216         [27] "Data memory protection ID trap",
 217         [28] "Unaligned data reference trap",
 218 };
 219
 220 const char *trap_name(unsigned long code)
 221 {
 222         const char *t = NULL;
 223
 224         if (code < ARRAY_SIZE(trap_description))
 225                 t = trap_description[code];
 226
 227         return t ? t : "Unknown trap";
 228 }
 229
 230 /*
 231  * Print out info about fatal segfaults, if the show_unhandled_signals
 232  * sysctl is set:
 233  */
 234 static inline void
 235 show_signal_msg(struct pt_regs *regs, unsigned long code,
 236                 unsigned long address, struct task_struct *tsk,
 237                 struct vm_area_struct *vma)
 238 {
 239         if (!unhandled_signal(tsk, SIGSEGV))
 240                 return;
 241
 242         if (!printk_ratelimit())
 243                 return;
 244
 245         pr_warn("\n");
 246         pr_warn("do_page_fault() command='%s' type=%lu address=0x%08lx",
 247             tsk->comm, code, address);
 248         print_vma_addr(KERN_CONT " in ", regs->iaoq[0]);
 249
 250         pr_cont("\ntrap #%lu: %s%c", code, trap_name(code),
 251                 vma ? ',':'\n');
 252
 253         if (vma)
 254                 pr_cont(" vm_start = 0x%08lx, vm_end = 0x%08lx\n",
 255                         vma->vm_start, vma->vm_end);
 256
 257         show_regs(regs);
 258 }
 259
 260 void do_page_fault(struct pt_regs *regs, unsigned long code,
 261                               unsigned long address)
 262 {
 263         struct vm_area_struct *vma, *prev_vma;
 264         struct task_struct *tsk;
 265         struct mm_struct *mm;
 266         unsigned long acc_type;
 267         vm_fault_t fault = 0;
 268         unsigned int flags;
 269
 270         if (faulthandler_disabled())
 271                 goto no_context;
 272
 273         tsk = current;
 274         mm = tsk->mm;
 275         if (!mm)
 276                 goto no_context;
 277
 278         flags = FAULT_FLAG_DEFAULT;
 279         if (user_mode(regs))
 280                 flags |= FAULT_FLAG_USER;
 281
 282         acc_type = parisc_acctyp(code, regs->iir);
 283         if (acc_type & VM_WRITE)
 284                 flags |= FAULT_FLAG_WRITE;
 285         perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
 286 retry:
 287         mmap_read_lock(mm);
 288         vma = find_vma_prev(mm, address, &prev_vma);
 289         if (!vma || address < vma->vm_start)
 290                 goto check_expansion;
 291 /*
 292  * Ok, we have a good vm_area for this memory access. We still need to
 293  * check the access permissions.
 294  */
 295
 296 good_area:
 297
 298         if ((vma->vm_flags & acc_type) != acc_type)
 299                 goto bad_area;
 300
 301         /*
 302          * If for any reason at all we couldn't handle the fault, make
 303          * sure we exit gracefully rather than endlessly redo the
 304          * fault.
 305          */
 306
 307         fault = handle_mm_fault(vma, address, flags, regs);
 308
 309         if (fault_signal_pending(fault, regs))
 310                 return;
 311
 312         if (unlikely(fault & VM_FAULT_ERROR)) {
 313                 /*
 314                  * We hit a shared mapping outside of the file, or some
 315                  * other thing happened to us that made us unable to
 316                  * handle the page fault gracefully.
 317                  */
 318                 if (fault & VM_FAULT_OOM)
 319                         goto out_of_memory;
 320                 else if (fault & VM_FAULT_SIGSEGV)
 321                         goto bad_area;
 322                 else if (fault & (VM_FAULT_SIGBUS|VM_FAULT_HWPOISON|
 323                                   VM_FAULT_HWPOISON_LARGE))
 324                         goto bad_area;
 325                 BUG();
 326         }
 327         if (flags & FAULT_FLAG_ALLOW_RETRY) {
 328                 if (fault & VM_FAULT_RETRY) {
 329                         /*
 330                          * No need to mmap_read_unlock(mm) as we would
 331                          * have already released it in __lock_page_or_retry
 332                          * in mm/filemap.c.
 333                          */
 334                         flags |= FAULT_FLAG_TRIED;
 335                         goto retry;
 336                 }
 337         }
 338         mmap_read_unlock(mm);
 339         return;
 340
 341 check_expansion:
 342         vma = prev_vma;
 343         if (vma && (expand_stack(vma, address) == 0))
 344                 goto good_area;
 345
 346 /*
 347  * Something tried to access memory that isn't in our memory map..
 348  */
 349 bad_area:
 350         mmap_read_unlock(mm);
 351
 352         if (user_mode(regs)) {
 353                 int signo, si_code;
 354
 355                 switch (code) {
 356                 case 15:        /* Data TLB miss fault/Data page fault */
 357                         /* send SIGSEGV when outside of vma */
 358                         if (!vma ||
 359                             address < vma->vm_start || address >= vma->vm_end) {
 360                                 signo = SIGSEGV;
 361                                 si_code = SEGV_MAPERR;
 362                                 break;
 363                         }
 364
 365                         /* send SIGSEGV for wrong permissions */
 366                         if ((vma->vm_flags & acc_type) != acc_type) {
 367                                 signo = SIGSEGV;
 368                                 si_code = SEGV_ACCERR;
 369                                 break;
 370                         }
 371
 372                         /* probably address is outside of mapped file */
 373                         fallthrough;
 374                 case 17:        /* NA data TLB miss / page fault */
 375                 case 18:        /* Unaligned access - PCXS only */
 376                         signo = SIGBUS;
 377                         si_code = (code == 18) ? BUS_ADRALN : BUS_ADRERR;
 378                         break;
 379                 case 16:        /* Non-access instruction TLB miss fault */
 380                 case 26:        /* PCXL: Data memory access rights trap */
 381                 default:
 382                         signo = SIGSEGV;
 383                         si_code = (code == 26) ? SEGV_ACCERR : SEGV_MAPERR;
 384                         break;
 385                 }
 386 #ifdef CONFIG_MEMORY_FAILURE
 387                 if (fault & (VM_FAULT_HWPOISON|VM_FAULT_HWPOISON_LARGE)) {
 388                         unsigned int lsb = 0;
 389                         printk(KERN_ERR
 390         "MCE: Killing %s:%d due to hardware memory corruption fault at %08lx\n",
 391                         tsk->comm, tsk->pid, address);
 392                         /*
 393                          * Either small page or large page may be poisoned.
 394                          * In other words, VM_FAULT_HWPOISON_LARGE and
 395                          * VM_FAULT_HWPOISON are mutually exclusive.
 396                          */
 397                         if (fault & VM_FAULT_HWPOISON_LARGE)
 398                                 lsb = hstate_index_to_shift(VM_FAULT_GET_HINDEX(fault));
 399                         else if (fault & VM_FAULT_HWPOISON)
 400                                 lsb = PAGE_SHIFT;
 401
 402                         force_sig_mceerr(BUS_MCEERR_AR, (void __user *) address,
 403                                          lsb);
 404                         return;
 405                 }
 406 #endif
 407                 show_signal_msg(regs, code, address, tsk, vma);
 408
 409                 force_sig_fault(signo, si_code, (void __user *) address);
 410                 return;
 411         }
 412
 413 no_context:
 414
 415         if (!user_mode(regs) && fixup_exception(regs)) {
 416                 return;
 417         }
 418
 419         parisc_terminate("Bad Address (null pointer deref?)", regs, code, address);
 420
 421   out_of_memory:
 422         mmap_read_unlock(mm);
 423         if (!user_mode(regs))
 424                 goto no_context;
 425         pagefault_out_of_memory();
 426 }