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/setup.h>
  30 #include <asm/smp.h>
  31 #include <asm/traps.h>
  32 #include <asm/uaccess.h>
  33
  34 #include "mm_32.h"
  35
  36 int show_unhandled_signals = 1;
  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 static unsigned long compute_si_addr(struct pt_regs *regs, int text_fault)
 145 {
 146         unsigned int insn;
 147
 148         if (text_fault)
 149                 return regs->pc;
 150
 151         if (regs->psr & PSR_PS)
 152                 insn = *(unsigned int *) regs->pc;
 153         else
 154                 __get_user(insn, (unsigned int *) regs->pc);
 155
 156         return safe_compute_effective_address(regs, insn);
 157 }
 158
 159 static noinline void do_fault_siginfo(int code, int sig, struct pt_regs *regs,
 160                                       int text_fault)
 161 {
 162         unsigned long addr = compute_si_addr(regs, text_fault);
 163
 164         __do_fault_siginfo(code, sig, regs, addr);
 165 }
 166
 167 asmlinkage void do_sparc_fault(struct pt_regs *regs, int text_fault, int write,
 168                                unsigned long address)
 169 {
 170         struct vm_area_struct *vma;
 171         struct task_struct *tsk = current;
 172         struct mm_struct *mm = tsk->mm;
 173         unsigned int fixup;
 174         unsigned long g2;
 175         int from_user = !(regs->psr & PSR_PS);
 176         int fault, code;
 177         unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
 178
 179         if (text_fault)
 180                 address = regs->pc;
 181
 182         /*
 183          * We fault-in kernel-space virtual memory on-demand. The
 184          * 'reference' page table is init_mm.pgd.
 185          *
 186          * NOTE! We MUST NOT take any locks for this case. We may
 187          * be in an interrupt or a critical region, and should
 188          * only copy the information from the master page table,
 189          * nothing more.
 190          */
 191         code = SEGV_MAPERR;
 192         if (address >= TASK_SIZE)
 193                 goto vmalloc_fault;
 194
 195         /*
 196          * If we're in an interrupt or have no user
 197          * context, we must not take the fault..
 198          */
 199         if (in_atomic() || !mm)
 200                 goto no_context;
 201
 202         perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
 203
 204 retry:
 205         down_read(&mm->mmap_sem);
 206
 207         if (!from_user && address >= PAGE_OFFSET)
 208                 goto bad_area;
 209
 210         vma = find_vma(mm, address);
 211         if (!vma)
 212                 goto bad_area;
 213         if (vma->vm_start <= address)
 214                 goto good_area;
 215         if (!(vma->vm_flags & VM_GROWSDOWN))
 216                 goto bad_area;
 217         if (expand_stack(vma, address))
 218                 goto bad_area;
 219         /*
 220          * Ok, we have a good vm_area for this memory access, so
 221          * we can handle it..
 222          */
 223 good_area:
 224         code = SEGV_ACCERR;
 225         if (write) {
 226                 if (!(vma->vm_flags & VM_WRITE))
 227                         goto bad_area;
 228         } else {
 229                 /* Allow reads even for write-only mappings */
 230                 if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
 231                         goto bad_area;
 232         }
 233
 234         if (from_user)
 235                 flags |= FAULT_FLAG_USER;
 236         if (write)
 237                 flags |= FAULT_FLAG_WRITE;
 238
 239         /*
 240          * If for any reason at all we couldn't handle the fault,
 241          * make sure we exit gracefully rather than endlessly redo
 242          * the fault.
 243          */
 244         fault = handle_mm_fault(mm, vma, address, flags);
 245
 246         if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
 247                 return;
 248
 249         if (unlikely(fault & VM_FAULT_ERROR)) {
 250                 if (fault & VM_FAULT_OOM)
 251                         goto out_of_memory;
 252                 else if (fault & VM_FAULT_SIGBUS)
 253                         goto do_sigbus;
 254                 BUG();
 255         }
 256
 257         if (flags & FAULT_FLAG_ALLOW_RETRY) {
 258                 if (fault & VM_FAULT_MAJOR) {
 259                         current->maj_flt++;
 260                         perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ,
 261                                       1, regs, address);
 262                 } else {
 263                         current->min_flt++;
 264                         perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN,
 265                                       1, regs, address);
 266                 }
 267                 if (fault & VM_FAULT_RETRY) {
 268                         flags &= ~FAULT_FLAG_ALLOW_RETRY;
 269                         flags |= FAULT_FLAG_TRIED;
 270
 271                         /* No need to up_read(&mm->mmap_sem) as we would
 272                          * have already released it in __lock_page_or_retry
 273                          * in mm/filemap.c.
 274                          */
 275
 276                         goto retry;
 277                 }
 278         }
 279
 280         up_read(&mm->mmap_sem);
 281         return;
 282
 283         /*
 284          * Something tried to access memory that isn't in our memory map..
 285          * Fix it, but check if it's kernel or user first..
 286          */
 287 bad_area:
 288         up_read(&mm->mmap_sem);
 289
 290 bad_area_nosemaphore:
 291         /* User mode accesses just cause a SIGSEGV */
 292         if (from_user) {
 293                 do_fault_siginfo(code, SIGSEGV, regs, text_fault);
 294                 return;
 295         }
 296
 297         /* Is this in ex_table? */
 298 no_context:
 299         g2 = regs->u_regs[UREG_G2];
 300         if (!from_user) {
 301                 fixup = search_extables_range(regs->pc, &g2);
 302                 /* Values below 10 are reserved for other things */
 303                 if (fixup > 10) {
 304                         extern const unsigned __memset_start[];
 305                         extern const unsigned __memset_end[];
 306                         extern const unsigned __csum_partial_copy_start[];
 307                         extern const unsigned __csum_partial_copy_end[];
 308
 309 #ifdef DEBUG_EXCEPTIONS
 310                         printk("Exception: PC<%08lx> faddr<%08lx>\n",
 311                                regs->pc, address);
 312                         printk("EX_TABLE: insn<%08lx> fixup<%08x> g2<%08lx>\n",
 313                                 regs->pc, fixup, g2);
 314 #endif
 315                         if ((regs->pc >= (unsigned long)__memset_start &&
 316                              regs->pc < (unsigned long)__memset_end) ||
 317                             (regs->pc >= (unsigned long)__csum_partial_copy_start &&
 318                              regs->pc < (unsigned long)__csum_partial_copy_end)) {
 319                                 regs->u_regs[UREG_I4] = address;
 320                                 regs->u_regs[UREG_I5] = regs->pc;
 321                         }
 322                         regs->u_regs[UREG_G2] = g2;
 323                         regs->pc = fixup;
 324                         regs->npc = regs->pc + 4;
 325                         return;
 326                 }
 327         }
 328
 329         unhandled_fault(address, tsk, regs);
 330         do_exit(SIGKILL);
 331
 332 /*
 333  * We ran out of memory, or some other thing happened to us that made
 334  * us unable to handle the page fault gracefully.
 335  */
 336 out_of_memory:
 337         up_read(&mm->mmap_sem);
 338         if (from_user) {
 339                 pagefault_out_of_memory();
 340                 return;
 341         }
 342         goto no_context;
 343
 344 do_sigbus:
 345         up_read(&mm->mmap_sem);
 346         do_fault_siginfo(BUS_ADRERR, SIGBUS, regs, text_fault);
 347         if (!from_user)
 348                 goto no_context;
 349
 350 vmalloc_fault:
 351         {
 352                 /*
 353                  * Synchronize this task's top level page-table
 354                  * with the 'reference' page table.
 355                  */
 356                 int offset = pgd_index(address);
 357                 pgd_t *pgd, *pgd_k;
 358                 pmd_t *pmd, *pmd_k;
 359
 360                 pgd = tsk->active_mm->pgd + offset;
 361                 pgd_k = init_mm.pgd + offset;
 362
 363                 if (!pgd_present(*pgd)) {
 364                         if (!pgd_present(*pgd_k))
 365                                 goto bad_area_nosemaphore;
 366                         pgd_val(*pgd) = pgd_val(*pgd_k);
 367                         return;
 368                 }
 369
 370                 pmd = pmd_offset(pgd, address);
 371                 pmd_k = pmd_offset(pgd_k, address);
 372
 373                 if (pmd_present(*pmd) || !pmd_present(*pmd_k))
 374                         goto bad_area_nosemaphore;
 375
 376                 *pmd = *pmd_k;
 377                 return;
 378         }
 379 }
 380
 381 /* This always deals with user addresses. */
 382 static void force_user_fault(unsigned long address, int write)
 383 {
 384         struct vm_area_struct *vma;
 385         struct task_struct *tsk = current;
 386         struct mm_struct *mm = tsk->mm;
 387         unsigned int flags = FAULT_FLAG_USER;
 388         int code;
 389
 390         code = SEGV_MAPERR;
 391
 392         down_read(&mm->mmap_sem);
 393         vma = find_vma(mm, address);
 394         if (!vma)
 395                 goto bad_area;
 396         if (vma->vm_start <= address)
 397                 goto good_area;
 398         if (!(vma->vm_flags & VM_GROWSDOWN))
 399                 goto bad_area;
 400         if (expand_stack(vma, address))
 401                 goto bad_area;
 402 good_area:
 403         code = SEGV_ACCERR;
 404         if (write) {
 405                 if (!(vma->vm_flags & VM_WRITE))
 406                         goto bad_area;
 407                 flags |= FAULT_FLAG_WRITE;
 408         } else {
 409                 if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
 410                         goto bad_area;
 411         }
 412         switch (handle_mm_fault(mm, vma, address, flags)) {
 413         case VM_FAULT_SIGBUS:
 414         case VM_FAULT_OOM:
 415                 goto do_sigbus;
 416         }
 417         up_read(&mm->mmap_sem);
 418         return;
 419 bad_area:
 420         up_read(&mm->mmap_sem);
 421         __do_fault_siginfo(code, SIGSEGV, tsk->thread.kregs, address);
 422         return;
 423
 424 do_sigbus:
 425         up_read(&mm->mmap_sem);
 426         __do_fault_siginfo(BUS_ADRERR, SIGBUS, tsk->thread.kregs, address);
 427 }
 428
 429 static void check_stack_aligned(unsigned long sp)
 430 {
 431         if (sp & 0x7UL)
 432                 force_sig(SIGILL, current);
 433 }
 434
 435 void window_overflow_fault(void)
 436 {
 437         unsigned long sp;
 438
 439         sp = current_thread_info()->rwbuf_stkptrs[0];
 440         if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
 441                 force_user_fault(sp + 0x38, 1);
 442         force_user_fault(sp, 1);
 443
 444         check_stack_aligned(sp);
 445 }
 446
 447 void window_underflow_fault(unsigned long sp)
 448 {
 449         if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
 450                 force_user_fault(sp + 0x38, 0);
 451         force_user_fault(sp, 0);
 452
 453         check_stack_aligned(sp);
 454 }
 455
 456 void window_ret_fault(struct pt_regs *regs)
 457 {
 458         unsigned long sp;
 459
 460         sp = regs->u_regs[UREG_FP];
 461         if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
 462                 force_user_fault(sp + 0x38, 0);
 463         force_user_fault(sp, 0);
 464
 465         check_stack_aligned(sp);
 466 }