arch/sparc/mm/fault_32.c

   1 /*
   2  * fault.c:  Page fault handlers for the Sparc.
   3  *
   4  * Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu)
   5  * Copyright (C) 1996 Eddie C. Dost (ecd@skynet.be)
   6  * Copyright (C) 1997 Jakub Jelinek (jj@sunsite.mff.cuni.cz)
   7  */
   8
   9 #include <asm/head.h>
  10
  11 #include <linux/string.h>
  12 #include <linux/types.h>
  13 #include <linux/sched.h>
  14 #include <linux/ptrace.h>
  15 #include <linux/mman.h>
  16 #include <linux/threads.h>
  17 #include <linux/kernel.h>
  18 #include <linux/signal.h>
  19 #include <linux/mm.h>
  20 #include <linux/smp.h>
  21 #include <linux/perf_event.h>
  22 #include <linux/interrupt.h>
  23 #include <linux/kdebug.h>
  24
  25 #include <asm/page.h>
  26 #include <asm/pgtable.h>
  27 #include <asm/openprom.h>
  28 #include <asm/oplib.h>
  29 #include <asm/smp.h>
  30 #include <asm/traps.h>
  31 #include <asm/uaccess.h>
  32
  33 int show_unhandled_signals = 1;
  34
  35 static void unhandled_fault(unsigned long, struct task_struct *,
  36                 struct pt_regs *) __attribute__ ((noreturn));
  37
  38 static void __noreturn unhandled_fault(unsigned long address,
  39                                        struct task_struct *tsk,
  40                                        struct pt_regs *regs)
  41 {
  42         if ((unsigned long) address < PAGE_SIZE) {
  43                 printk(KERN_ALERT
  44                     "Unable to handle kernel NULL pointer dereference\n");
  45         } else {
  46                 printk(KERN_ALERT "Unable to handle kernel paging request at virtual address %08lx\n",
  47                        address);
  48         }
  49         printk(KERN_ALERT "tsk->{mm,active_mm}->context = %08lx\n",
  50                 (tsk->mm ? tsk->mm->context : tsk->active_mm->context));
  51         printk(KERN_ALERT "tsk->{mm,active_mm}->pgd = %08lx\n",
  52                 (tsk->mm ? (unsigned long) tsk->mm->pgd :
  53                         (unsigned long) tsk->active_mm->pgd));
  54         die_if_kernel("Oops", regs);
  55 }
  56
  57 asmlinkage int lookup_fault(unsigned long pc, unsigned long ret_pc,
  58                             unsigned long address)
  59 {
  60         struct pt_regs regs;
  61         unsigned long g2;
  62         unsigned int insn;
  63         int i;
  64
  65         i = search_extables_range(ret_pc, &g2);
  66         switch (i) {
  67         case 3:
  68                 /* load & store will be handled by fixup */
  69                 return 3;
  70
  71         case 1:
  72                 /* store will be handled by fixup, load will bump out */
  73                 /* for _to_ macros */
  74                 insn = *((unsigned int *) pc);
  75                 if ((insn >> 21) & 1)
  76                         return 1;
  77                 break;
  78
  79         case 2:
  80                 /* load will be handled by fixup, store will bump out */
  81                 /* for _from_ macros */
  82                 insn = *((unsigned int *) pc);
  83                 if (!((insn >> 21) & 1) || ((insn>>19)&0x3f) == 15)
  84                         return 2;
  85                 break;
  86
  87         default:
  88                 break;
  89         }
  90
  91         memset(&regs, 0, sizeof(regs));
  92         regs.pc = pc;
  93         regs.npc = pc + 4;
  94         __asm__ __volatile__(
  95                 "rd %%psr, %0\n\t"
  96                 "nop\n\t"
  97                 "nop\n\t"
  98                 "nop\n" : "=r" (regs.psr));
  99         unhandled_fault(address, current, &regs);
 100
 101         /* Not reached */
 102         return 0;
 103 }
 104
 105 static inline void
 106 show_signal_msg(struct pt_regs *regs, int sig, int code,
 107                 unsigned long address, struct task_struct *tsk)
 108 {
 109         if (!unhandled_signal(tsk, sig))
 110                 return;
 111
 112         if (!printk_ratelimit())
 113                 return;
 114
 115         printk("%s%s[%d]: segfault at %lx ip %p (rpc %p) sp %p error %x",
 116                task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
 117                tsk->comm, task_pid_nr(tsk), address,
 118                (void *)regs->pc, (void *)regs->u_regs[UREG_I7],
 119                (void *)regs->u_regs[UREG_FP], code);
 120
 121         print_vma_addr(KERN_CONT " in ", regs->pc);
 122
 123         printk(KERN_CONT "\n");
 124 }
 125
 126 static void __do_fault_siginfo(int code, int sig, struct pt_regs *regs,
 127                                unsigned long addr)
 128 {
 129         siginfo_t info;
 130
 131         info.si_signo = sig;
 132         info.si_code = code;
 133         info.si_errno = 0;
 134         info.si_addr = (void __user *) addr;
 135         info.si_trapno = 0;
 136
 137         if (unlikely(show_unhandled_signals))
 138                 show_signal_msg(regs, sig, info.si_code,
 139                                 addr, current);
 140
 141         force_sig_info (sig, &info, current);
 142 }
 143
 144 extern unsigned long safe_compute_effective_address(struct pt_regs *,
 145                                                     unsigned int);
 146
 147 static unsigned long compute_si_addr(struct pt_regs *regs, int text_fault)
 148 {
 149         unsigned int insn;
 150
 151         if (text_fault)
 152                 return regs->pc;
 153
 154         if (regs->psr & PSR_PS)
 155                 insn = *(unsigned int *) regs->pc;
 156         else
 157                 __get_user(insn, (unsigned int *) regs->pc);
 158
 159         return safe_compute_effective_address(regs, insn);
 160 }
 161
 162 static noinline void do_fault_siginfo(int code, int sig, struct pt_regs *regs,
 163                                       int text_fault)
 164 {
 165         unsigned long addr = compute_si_addr(regs, text_fault);
 166
 167         __do_fault_siginfo(code, sig, regs, addr);
 168 }
 169
 170 asmlinkage void do_sparc_fault(struct pt_regs *regs, int text_fault, int write,
 171                                unsigned long address)
 172 {
 173         struct vm_area_struct *vma;
 174         struct task_struct *tsk = current;
 175         struct mm_struct *mm = tsk->mm;
 176         unsigned int fixup;
 177         unsigned long g2;
 178         int from_user = !(regs->psr & PSR_PS);
 179         int fault, code;
 180         unsigned int flags = (FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
 181                               (write ? FAULT_FLAG_WRITE : 0));
 182
 183         if (text_fault)
 184                 address = regs->pc;
 185
 186         /*
 187          * We fault-in kernel-space virtual memory on-demand. The
 188          * 'reference' page table is init_mm.pgd.
 189          *
 190          * NOTE! We MUST NOT take any locks for this case. We may
 191          * be in an interrupt or a critical region, and should
 192          * only copy the information from the master page table,
 193          * nothing more.
 194          */
 195         code = SEGV_MAPERR;
 196         if (address >= TASK_SIZE)
 197                 goto vmalloc_fault;
 198
 199         /*
 200          * If we're in an interrupt or have no user
 201          * context, we must not take the fault..
 202          */
 203         if (in_atomic() || !mm)
 204                 goto no_context;
 205
 206         perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
 207
 208 retry:
 209         down_read(&mm->mmap_sem);
 210
 211         if (!from_user && address >= PAGE_OFFSET)
 212                 goto bad_area;
 213
 214         vma = find_vma(mm, address);
 215         if (!vma)
 216                 goto bad_area;
 217         if (vma->vm_start <= address)
 218                 goto good_area;
 219         if (!(vma->vm_flags & VM_GROWSDOWN))
 220                 goto bad_area;
 221         if (expand_stack(vma, address))
 222                 goto bad_area;
 223         /*
 224          * Ok, we have a good vm_area for this memory access, so
 225          * we can handle it..
 226          */
 227 good_area:
 228         code = SEGV_ACCERR;
 229         if (write) {
 230                 if (!(vma->vm_flags & VM_WRITE))
 231                         goto bad_area;
 232         } else {
 233                 /* Allow reads even for write-only mappings */
 234                 if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
 235                         goto bad_area;
 236         }
 237
 238         /*
 239          * If for any reason at all we couldn't handle the fault,
 240          * make sure we exit gracefully rather than endlessly redo
 241          * the fault.
 242          */
 243         fault = handle_mm_fault(mm, vma, address, flags);
 244
 245         if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
 246                 return;
 247
 248         if (unlikely(fault & VM_FAULT_ERROR)) {
 249                 if (fault & VM_FAULT_OOM)
 250                         goto out_of_memory;
 251                 else if (fault & VM_FAULT_SIGBUS)
 252                         goto do_sigbus;
 253                 BUG();
 254         }
 255
 256         if (flags & FAULT_FLAG_ALLOW_RETRY) {
 257                 if (fault & VM_FAULT_MAJOR) {
 258                         current->maj_flt++;
 259                         perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ,
 260                                       1, regs, address);
 261                 } else {
 262                         current->min_flt++;
 263                         perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN,
 264                                       1, regs, address);
 265                 }
 266                 if (fault & VM_FAULT_RETRY) {
 267                         flags &= ~FAULT_FLAG_ALLOW_RETRY;
 268                         flags |= FAULT_FLAG_TRIED;
 269
 270                         /* No need to up_read(&mm->mmap_sem) as we would
 271                          * have already released it in __lock_page_or_retry
 272                          * in mm/filemap.c.
 273                          */
 274
 275                         goto retry;
 276                 }
 277         }
 278
 279         up_read(&mm->mmap_sem);
 280         return;
 281
 282         /*
 283          * Something tried to access memory that isn't in our memory map..
 284          * Fix it, but check if it's kernel or user first..
 285          */
 286 bad_area:
 287         up_read(&mm->mmap_sem);
 288
 289 bad_area_nosemaphore:
 290         /* User mode accesses just cause a SIGSEGV */
 291         if (from_user) {
 292                 do_fault_siginfo(code, SIGSEGV, regs, text_fault);
 293                 return;
 294         }
 295
 296         /* Is this in ex_table? */
 297 no_context:
 298         g2 = regs->u_regs[UREG_G2];
 299         if (!from_user) {
 300                 fixup = search_extables_range(regs->pc, &g2);
 301                 /* Values below 10 are reserved for other things */
 302                 if (fixup > 10) {
 303                         extern const unsigned __memset_start[];
 304                         extern const unsigned __memset_end[];
 305                         extern const unsigned __csum_partial_copy_start[];
 306                         extern const unsigned __csum_partial_copy_end[];
 307
 308 #ifdef DEBUG_EXCEPTIONS
 309                         printk("Exception: PC<%08lx> faddr<%08lx>\n",
 310                                regs->pc, address);
 311                         printk("EX_TABLE: insn<%08lx> fixup<%08x> g2<%08lx>\n",
 312                                 regs->pc, fixup, g2);
 313 #endif
 314                         if ((regs->pc >= (unsigned long)__memset_start &&
 315                              regs->pc < (unsigned long)__memset_end) ||
 316                             (regs->pc >= (unsigned long)__csum_partial_copy_start &&
 317                              regs->pc < (unsigned long)__csum_partial_copy_end)) {
 318                                 regs->u_regs[UREG_I4] = address;
 319                                 regs->u_regs[UREG_I5] = regs->pc;
 320                         }
 321                         regs->u_regs[UREG_G2] = g2;
 322                         regs->pc = fixup;
 323                         regs->npc = regs->pc + 4;
 324                         return;
 325                 }
 326         }
 327
 328         unhandled_fault(address, tsk, regs);
 329         do_exit(SIGKILL);
 330
 331 /*
 332  * We ran out of memory, or some other thing happened to us that made
 333  * us unable to handle the page fault gracefully.
 334  */
 335 out_of_memory:
 336         up_read(&mm->mmap_sem);
 337         if (from_user) {
 338                 pagefault_out_of_memory();
 339                 return;
 340         }
 341         goto no_context;
 342
 343 do_sigbus:
 344         up_read(&mm->mmap_sem);
 345         do_fault_siginfo(BUS_ADRERR, SIGBUS, regs, text_fault);
 346         if (!from_user)
 347                 goto no_context;
 348
 349 vmalloc_fault:
 350         {
 351                 /*
 352                  * Synchronize this task's top level page-table
 353                  * with the 'reference' page table.
 354                  */
 355                 int offset = pgd_index(address);
 356                 pgd_t *pgd, *pgd_k;
 357                 pmd_t *pmd, *pmd_k;
 358
 359                 pgd = tsk->active_mm->pgd + offset;
 360                 pgd_k = init_mm.pgd + offset;
 361
 362                 if (!pgd_present(*pgd)) {
 363                         if (!pgd_present(*pgd_k))
 364                                 goto bad_area_nosemaphore;
 365                         pgd_val(*pgd) = pgd_val(*pgd_k);
 366                         return;
 367                 }
 368
 369                 pmd = pmd_offset(pgd, address);
 370                 pmd_k = pmd_offset(pgd_k, address);
 371
 372                 if (pmd_present(*pmd) || !pmd_present(*pmd_k))
 373                         goto bad_area_nosemaphore;
 374
 375                 *pmd = *pmd_k;
 376                 return;
 377         }
 378 }
 379
 380 /* This always deals with user addresses. */
 381 static void force_user_fault(unsigned long address, int write)
 382 {
 383         struct vm_area_struct *vma;
 384         struct task_struct *tsk = current;
 385         struct mm_struct *mm = tsk->mm;
 386         int code;
 387
 388         code = SEGV_MAPERR;
 389
 390         down_read(&mm->mmap_sem);
 391         vma = find_vma(mm, address);
 392         if (!vma)
 393                 goto bad_area;
 394         if (vma->vm_start <= address)
 395                 goto good_area;
 396         if (!(vma->vm_flags & VM_GROWSDOWN))
 397                 goto bad_area;
 398         if (expand_stack(vma, address))
 399                 goto bad_area;
 400 good_area:
 401         code = SEGV_ACCERR;
 402         if (write) {
 403                 if (!(vma->vm_flags & VM_WRITE))
 404                         goto bad_area;
 405         } else {
 406                 if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
 407                         goto bad_area;
 408         }
 409         switch (handle_mm_fault(mm, vma, address, write ? FAULT_FLAG_WRITE : 0)) {
 410         case VM_FAULT_SIGBUS:
 411         case VM_FAULT_OOM:
 412                 goto do_sigbus;
 413         }
 414         up_read(&mm->mmap_sem);
 415         return;
 416 bad_area:
 417         up_read(&mm->mmap_sem);
 418         __do_fault_siginfo(code, SIGSEGV, tsk->thread.kregs, address);
 419         return;
 420
 421 do_sigbus:
 422         up_read(&mm->mmap_sem);
 423         __do_fault_siginfo(BUS_ADRERR, SIGBUS, tsk->thread.kregs, address);
 424 }
 425
 426 static void check_stack_aligned(unsigned long sp)
 427 {
 428         if (sp & 0x7UL)
 429                 force_sig(SIGILL, current);
 430 }
 431
 432 void window_overflow_fault(void)
 433 {
 434         unsigned long sp;
 435
 436         sp = current_thread_info()->rwbuf_stkptrs[0];
 437         if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
 438                 force_user_fault(sp + 0x38, 1);
 439         force_user_fault(sp, 1);
 440
 441         check_stack_aligned(sp);
 442 }
 443
 444 void window_underflow_fault(unsigned long sp)
 445 {
 446         if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
 447                 force_user_fault(sp + 0x38, 0);
 448         force_user_fault(sp, 0);
 449
 450         check_stack_aligned(sp);
 451 }
 452
 453 void window_ret_fault(struct pt_regs *regs)
 454 {
 455         unsigned long sp;
 456
 457         sp = regs->u_regs[UREG_FP];
 458         if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
 459                 force_user_fault(sp + 0x38, 0);
 460         force_user_fault(sp, 0);
 461
 462         check_stack_aligned(sp);
 463 }