arch/unicore32/mm/fault.c

   1 /*
   2  * linux/arch/unicore32/mm/fault.c
   3  *
   4  * Code specific to PKUnity SoC and UniCore ISA
   5  *
   6  * Copyright (C) 2001-2010 GUAN Xue-tao
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  */
  12 #include <linux/extable.h>
  13 #include <linux/signal.h>
  14 #include <linux/mm.h>
  15 #include <linux/hardirq.h>
  16 #include <linux/init.h>
  17 #include <linux/kprobes.h>
  18 #include <linux/uaccess.h>
  19 #include <linux/page-flags.h>
  20 #include <linux/sched.h>
  21 #include <linux/io.h>
  22
  23 #include <asm/pgtable.h>
  24 #include <asm/tlbflush.h>
  25
  26 /*
  27  * Fault status register encodings.  We steal bit 31 for our own purposes.
  28  */
  29 #define FSR_LNX_PF              (1 << 31)
  30
  31 static inline int fsr_fs(unsigned int fsr)
  32 {
  33         /* xyabcde will be abcde+xy */
  34         return (fsr & 31) + ((fsr & (3 << 5)) >> 5);
  35 }
  36
  37 /*
  38  * This is useful to dump out the page tables associated with
  39  * 'addr' in mm 'mm'.
  40  */
  41 void show_pte(struct mm_struct *mm, unsigned long addr)
  42 {
  43         pgd_t *pgd;
  44
  45         if (!mm)
  46                 mm = &init_mm;
  47
  48         printk(KERN_ALERT "pgd = %p\n", mm->pgd);
  49         pgd = pgd_offset(mm, addr);
  50         printk(KERN_ALERT "[%08lx] *pgd=%08lx", addr, pgd_val(*pgd));
  51
  52         do {
  53                 pmd_t *pmd;
  54                 pte_t *pte;
  55
  56                 if (pgd_none(*pgd))
  57                         break;
  58
  59                 if (pgd_bad(*pgd)) {
  60                         printk("(bad)");
  61                         break;
  62                 }
  63
  64                 pmd = pmd_offset((pud_t *) pgd, addr);
  65                 if (PTRS_PER_PMD != 1)
  66                         printk(", *pmd=%08lx", pmd_val(*pmd));
  67
  68                 if (pmd_none(*pmd))
  69                         break;
  70
  71                 if (pmd_bad(*pmd)) {
  72                         printk("(bad)");
  73                         break;
  74                 }
  75
  76                 /* We must not map this if we have highmem enabled */
  77                 if (PageHighMem(pfn_to_page(pmd_val(*pmd) >> PAGE_SHIFT)))
  78                         break;
  79
  80                 pte = pte_offset_map(pmd, addr);
  81                 printk(", *pte=%08lx", pte_val(*pte));
  82                 pte_unmap(pte);
  83         } while (0);
  84
  85         printk("\n");
  86 }
  87
  88 /*
  89  * Oops.  The kernel tried to access some page that wasn't present.
  90  */
  91 static void __do_kernel_fault(struct mm_struct *mm, unsigned long addr,
  92                 unsigned int fsr, struct pt_regs *regs)
  93 {
  94         /*
  95          * Are we prepared to handle this kernel fault?
  96          */
  97         if (fixup_exception(regs))
  98                 return;
  99
 100         /*
 101          * No handler, we'll have to terminate things with extreme prejudice.
 102          */
 103         bust_spinlocks(1);
 104         printk(KERN_ALERT
 105                "Unable to handle kernel %s at virtual address %08lx\n",
 106                (addr < PAGE_SIZE) ? "NULL pointer dereference" :
 107                "paging request", addr);
 108
 109         show_pte(mm, addr);
 110         die("Oops", regs, fsr);
 111         bust_spinlocks(0);
 112         do_exit(SIGKILL);
 113 }
 114
 115 /*
 116  * Something tried to access memory that isn't in our memory map..
 117  * User mode accesses just cause a SIGSEGV
 118  */
 119 static void __do_user_fault(struct task_struct *tsk, unsigned long addr,
 120                 unsigned int fsr, unsigned int sig, int code,
 121                 struct pt_regs *regs)
 122 {
 123         struct siginfo si;
 124
 125         tsk->thread.address = addr;
 126         tsk->thread.error_code = fsr;
 127         tsk->thread.trap_no = 14;
 128         si.si_signo = sig;
 129         si.si_errno = 0;
 130         si.si_code = code;
 131         si.si_addr = (void __user *)addr;
 132         force_sig_info(sig, &si, tsk);
 133 }
 134
 135 void do_bad_area(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 136 {
 137         struct task_struct *tsk = current;
 138         struct mm_struct *mm = tsk->active_mm;
 139
 140         /*
 141          * If we are in kernel mode at this point, we
 142          * have no context to handle this fault with.
 143          */
 144         if (user_mode(regs))
 145                 __do_user_fault(tsk, addr, fsr, SIGSEGV, SEGV_MAPERR, regs);
 146         else
 147                 __do_kernel_fault(mm, addr, fsr, regs);
 148 }
 149
 150 #define VM_FAULT_BADMAP         0x010000
 151 #define VM_FAULT_BADACCESS      0x020000
 152
 153 /*
 154  * Check that the permissions on the VMA allow for the fault which occurred.
 155  * If we encountered a write fault, we must have write permission, otherwise
 156  * we allow any permission.
 157  */
 158 static inline bool access_error(unsigned int fsr, struct vm_area_struct *vma)
 159 {
 160         unsigned int mask = VM_READ | VM_WRITE | VM_EXEC;
 161
 162         if (!(fsr ^ 0x12))      /* write? */
 163                 mask = VM_WRITE;
 164         if (fsr & FSR_LNX_PF)
 165                 mask = VM_EXEC;
 166
 167         return vma->vm_flags & mask ? false : true;
 168 }
 169
 170 static int __do_pf(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
 171                 unsigned int flags, struct task_struct *tsk)
 172 {
 173         struct vm_area_struct *vma;
 174         int fault;
 175
 176         vma = find_vma(mm, addr);
 177         fault = VM_FAULT_BADMAP;
 178         if (unlikely(!vma))
 179                 goto out;
 180         if (unlikely(vma->vm_start > addr))
 181                 goto check_stack;
 182
 183         /*
 184          * Ok, we have a good vm_area for this
 185          * memory access, so we can handle it.
 186          */
 187 good_area:
 188         if (access_error(fsr, vma)) {
 189                 fault = VM_FAULT_BADACCESS;
 190                 goto out;
 191         }
 192
 193         /*
 194          * If for any reason at all we couldn't handle the fault, make
 195          * sure we exit gracefully rather than endlessly redo the fault.
 196          */
 197         fault = handle_mm_fault(vma, addr & PAGE_MASK, flags);
 198         return fault;
 199
 200 check_stack:
 201         if (vma->vm_flags & VM_GROWSDOWN && !expand_stack(vma, addr))
 202                 goto good_area;
 203 out:
 204         return fault;
 205 }
 206
 207 static int do_pf(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 208 {
 209         struct task_struct *tsk;
 210         struct mm_struct *mm;
 211         int fault, sig, code;
 212         unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
 213
 214         tsk = current;
 215         mm = tsk->mm;
 216
 217         /*
 218          * If we're in an interrupt or have no user
 219          * context, we must not take the fault..
 220          */
 221         if (faulthandler_disabled() || !mm)
 222                 goto no_context;
 223
 224         if (user_mode(regs))
 225                 flags |= FAULT_FLAG_USER;
 226         if (!(fsr ^ 0x12))
 227                 flags |= FAULT_FLAG_WRITE;
 228
 229         /*
 230          * As per x86, we may deadlock here.  However, since the kernel only
 231          * validly references user space from well defined areas of the code,
 232          * we can bug out early if this is from code which shouldn't.
 233          */
 234         if (!down_read_trylock(&mm->mmap_sem)) {
 235                 if (!user_mode(regs)
 236                     && !search_exception_tables(regs->UCreg_pc))
 237                         goto no_context;
 238 retry:
 239                 down_read(&mm->mmap_sem);
 240         } else {
 241                 /*
 242                  * The above down_read_trylock() might have succeeded in
 243                  * which case, we'll have missed the might_sleep() from
 244                  * down_read()
 245                  */
 246                 might_sleep();
 247 #ifdef CONFIG_DEBUG_VM
 248                 if (!user_mode(regs) &&
 249                     !search_exception_tables(regs->UCreg_pc))
 250                         goto no_context;
 251 #endif
 252         }
 253
 254         fault = __do_pf(mm, addr, fsr, flags, tsk);
 255
 256         /* If we need to retry but a fatal signal is pending, handle the
 257          * signal first. We do not need to release the mmap_sem because
 258          * it would already be released in __lock_page_or_retry in
 259          * mm/filemap.c. */
 260         if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
 261                 return 0;
 262
 263         if (!(fault & VM_FAULT_ERROR) && (flags & FAULT_FLAG_ALLOW_RETRY)) {
 264                 if (fault & VM_FAULT_MAJOR)
 265                         tsk->maj_flt++;
 266                 else
 267                         tsk->min_flt++;
 268                 if (fault & VM_FAULT_RETRY) {
 269                         /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
 270                         * of starvation. */
 271                         flags &= ~FAULT_FLAG_ALLOW_RETRY;
 272                         goto retry;
 273                 }
 274         }
 275
 276         up_read(&mm->mmap_sem);
 277
 278         /*
 279          * Handle the "normal" case first - VM_FAULT_MAJOR
 280          */
 281         if (likely(!(fault &
 282                (VM_FAULT_ERROR | VM_FAULT_BADMAP | VM_FAULT_BADACCESS))))
 283                 return 0;
 284
 285         /*
 286          * If we are in kernel mode at this point, we
 287          * have no context to handle this fault with.
 288          */
 289         if (!user_mode(regs))
 290                 goto no_context;
 291
 292         if (fault & VM_FAULT_OOM) {
 293                 /*
 294                  * We ran out of memory, call the OOM killer, and return to
 295                  * userspace (which will retry the fault, or kill us if we
 296                  * got oom-killed)
 297                  */
 298                 pagefault_out_of_memory();
 299                 return 0;
 300         }
 301
 302         if (fault & VM_FAULT_SIGBUS) {
 303                 /*
 304                  * We had some memory, but were unable to
 305                  * successfully fix up this page fault.
 306                  */
 307                 sig = SIGBUS;
 308                 code = BUS_ADRERR;
 309         } else {
 310                 /*
 311                  * Something tried to access memory that
 312                  * isn't in our memory map..
 313                  */
 314                 sig = SIGSEGV;
 315                 code = fault == VM_FAULT_BADACCESS ? SEGV_ACCERR : SEGV_MAPERR;
 316         }
 317
 318         __do_user_fault(tsk, addr, fsr, sig, code, regs);
 319         return 0;
 320
 321 no_context:
 322         __do_kernel_fault(mm, addr, fsr, regs);
 323         return 0;
 324 }
 325
 326 /*
 327  * First Level Translation Fault Handler
 328  *
 329  * We enter here because the first level page table doesn't contain
 330  * a valid entry for the address.
 331  *
 332  * If the address is in kernel space (>= TASK_SIZE), then we are
 333  * probably faulting in the vmalloc() area.
 334  *
 335  * If the init_task's first level page tables contains the relevant
 336  * entry, we copy the it to this task.  If not, we send the process
 337  * a signal, fixup the exception, or oops the kernel.
 338  *
 339  * NOTE! We MUST NOT take any locks for this case. We may be in an
 340  * interrupt or a critical region, and should only copy the information
 341  * from the master page table, nothing more.
 342  */
 343 static int do_ifault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 344 {
 345         unsigned int index;
 346         pgd_t *pgd, *pgd_k;
 347         pmd_t *pmd, *pmd_k;
 348
 349         if (addr < TASK_SIZE)
 350                 return do_pf(addr, fsr, regs);
 351
 352         if (user_mode(regs))
 353                 goto bad_area;
 354
 355         index = pgd_index(addr);
 356
 357         pgd = cpu_get_pgd() + index;
 358         pgd_k = init_mm.pgd + index;
 359
 360         if (pgd_none(*pgd_k))
 361                 goto bad_area;
 362
 363         pmd_k = pmd_offset((pud_t *) pgd_k, addr);
 364         pmd = pmd_offset((pud_t *) pgd, addr);
 365
 366         if (pmd_none(*pmd_k))
 367                 goto bad_area;
 368
 369         set_pmd(pmd, *pmd_k);
 370         flush_pmd_entry(pmd);
 371         return 0;
 372
 373 bad_area:
 374         do_bad_area(addr, fsr, regs);
 375         return 0;
 376 }
 377
 378 /*
 379  * This abort handler always returns "fault".
 380  */
 381 static int do_bad(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 382 {
 383         return 1;
 384 }
 385
 386 static int do_good(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 387 {
 388         unsigned int res1, res2;
 389
 390         printk("dabt exception but no error!\n");
 391
 392         __asm__ __volatile__(
 393                         "mff %0,f0\n"
 394                         "mff %1,f1\n"
 395                         : "=r"(res1), "=r"(res2)
 396                         :
 397                         : "memory");
 398
 399         printk(KERN_EMERG "r0 :%08x  r1 :%08x\n", res1, res2);
 400         panic("shut up\n");
 401         return 0;
 402 }
 403
 404 static struct fsr_info {
 405         int (*fn) (unsigned long addr, unsigned int fsr, struct pt_regs *regs);
 406         int sig;
 407         int code;
 408         const char *name;
 409 } fsr_info[] = {
 410         /*
 411          * The following are the standard Unicore-I and UniCore-II aborts.
 412          */
 413         { do_good,      SIGBUS,  0,             "no error"              },
 414         { do_bad,       SIGBUS,  BUS_ADRALN,    "alignment exception"   },
 415         { do_bad,       SIGBUS,  BUS_OBJERR,    "external exception"    },
 416         { do_bad,       SIGBUS,  0,             "burst operation"       },
 417         { do_bad,       SIGBUS,  0,             "unknown 00100"         },
 418         { do_ifault,    SIGSEGV, SEGV_MAPERR,   "2nd level pt non-exist"},
 419         { do_bad,       SIGBUS,  0,             "2nd lvl large pt non-exist" },
 420         { do_bad,       SIGBUS,  0,             "invalid pte"           },
 421         { do_pf,        SIGSEGV, SEGV_MAPERR,   "page miss"             },
 422         { do_bad,       SIGBUS,  0,             "middle page miss"      },
 423         { do_bad,       SIGBUS,  0,             "large page miss"       },
 424         { do_pf,        SIGSEGV, SEGV_MAPERR,   "super page (section) miss" },
 425         { do_bad,       SIGBUS,  0,             "unknown 01100"         },
 426         { do_bad,       SIGBUS,  0,             "unknown 01101"         },
 427         { do_bad,       SIGBUS,  0,             "unknown 01110"         },
 428         { do_bad,       SIGBUS,  0,             "unknown 01111"         },
 429         { do_bad,       SIGBUS,  0,             "addr: up 3G or IO"     },
 430         { do_pf,        SIGSEGV, SEGV_ACCERR,   "read unreadable addr"  },
 431         { do_pf,        SIGSEGV, SEGV_ACCERR,   "write unwriteable addr"},
 432         { do_pf,        SIGSEGV, SEGV_ACCERR,   "exec unexecutable addr"},
 433         { do_bad,       SIGBUS,  0,             "unknown 10100"         },
 434         { do_bad,       SIGBUS,  0,             "unknown 10101"         },
 435         { do_bad,       SIGBUS,  0,             "unknown 10110"         },
 436         { do_bad,       SIGBUS,  0,             "unknown 10111"         },
 437         { do_bad,       SIGBUS,  0,             "unknown 11000"         },
 438         { do_bad,       SIGBUS,  0,             "unknown 11001"         },
 439         { do_bad,       SIGBUS,  0,             "unknown 11010"         },
 440         { do_bad,       SIGBUS,  0,             "unknown 11011"         },
 441         { do_bad,       SIGBUS,  0,             "unknown 11100"         },
 442         { do_bad,       SIGBUS,  0,             "unknown 11101"         },
 443         { do_bad,       SIGBUS,  0,             "unknown 11110"         },
 444         { do_bad,       SIGBUS,  0,             "unknown 11111"         }
 445 };
 446
 447 void __init hook_fault_code(int nr,
 448                 int (*fn) (unsigned long, unsigned int, struct pt_regs *),
 449                 int sig, int code, const char *name)
 450 {
 451         if (nr < 0 || nr >= ARRAY_SIZE(fsr_info))
 452                 BUG();
 453
 454         fsr_info[nr].fn   = fn;
 455         fsr_info[nr].sig  = sig;
 456         fsr_info[nr].code = code;
 457         fsr_info[nr].name = name;
 458 }
 459
 460 /*
 461  * Dispatch a data abort to the relevant handler.
 462  */
 463 asmlinkage void do_DataAbort(unsigned long addr, unsigned int fsr,
 464                         struct pt_regs *regs)
 465 {
 466         const struct fsr_info *inf = fsr_info + fsr_fs(fsr);
 467         struct siginfo info;
 468
 469         if (!inf->fn(addr, fsr & ~FSR_LNX_PF, regs))
 470                 return;
 471
 472         printk(KERN_ALERT "Unhandled fault: %s (0x%03x) at 0x%08lx\n",
 473                inf->name, fsr, addr);
 474
 475         info.si_signo = inf->sig;
 476         info.si_errno = 0;
 477         info.si_code = inf->code;
 478         info.si_addr = (void __user *)addr;
 479         uc32_notify_die("", regs, &info, fsr, 0);
 480 }
 481
 482 asmlinkage void do_PrefetchAbort(unsigned long addr,
 483                         unsigned int ifsr, struct pt_regs *regs)
 484 {
 485         const struct fsr_info *inf = fsr_info + fsr_fs(ifsr);
 486         struct siginfo info;
 487
 488         if (!inf->fn(addr, ifsr | FSR_LNX_PF, regs))
 489                 return;
 490
 491         printk(KERN_ALERT "Unhandled prefetch abort: %s (0x%03x) at 0x%08lx\n",
 492                inf->name, ifsr, addr);
 493
 494         info.si_signo = inf->sig;
 495         info.si_errno = 0;
 496         info.si_code = inf->code;
 497         info.si_addr = (void __user *)addr;
 498         uc32_notify_die("", regs, &info, ifsr, 0);
 499 }