arch/sparc/mm/fault.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/interrupt.h>
  22 #include <linux/module.h>
  23 #include <linux/kdebug.h>
  24
  25 #include <asm/system.h>
  26 #include <asm/page.h>
  27 #include <asm/pgtable.h>
  28 #include <asm/memreg.h>
  29 #include <asm/openprom.h>
  30 #include <asm/oplib.h>
  31 #include <asm/smp.h>
  32 #include <asm/traps.h>
  33 #include <asm/uaccess.h>
  34
  35 extern int prom_node_root;
  36
  37 /* At boot time we determine these two values necessary for setting
  38  * up the segment maps and page table entries (pte's).
  39  */
  40
  41 int num_segmaps, num_contexts;
  42 int invalid_segment;
  43
  44 /* various Virtual Address Cache parameters we find at boot time... */
  45
  46 int vac_size, vac_linesize, vac_do_hw_vac_flushes;
  47 int vac_entries_per_context, vac_entries_per_segment;
  48 int vac_entries_per_page;
  49
  50 /* Return how much physical memory we have.  */
  51 unsigned long probe_memory(void)
  52 {
  53         unsigned long total = 0;
  54         int i;
  55
  56         for (i = 0; sp_banks[i].num_bytes; i++)
  57                 total += sp_banks[i].num_bytes;
  58
  59         return total;
  60 }
  61
  62 extern void sun4c_complete_all_stores(void);
  63
  64 /* Whee, a level 15 NMI interrupt memory error.  Let's have fun... */
  65 asmlinkage void sparc_lvl15_nmi(struct pt_regs *regs, unsigned long serr,
  66                                 unsigned long svaddr, unsigned long aerr,
  67                                 unsigned long avaddr)
  68 {
  69         sun4c_complete_all_stores();
  70         printk("FAULT: NMI received\n");
  71         printk("SREGS: Synchronous Error %08lx\n", serr);
  72         printk("       Synchronous Vaddr %08lx\n", svaddr);
  73         printk("      Asynchronous Error %08lx\n", aerr);
  74         printk("      Asynchronous Vaddr %08lx\n", avaddr);
  75         if (sun4c_memerr_reg)
  76                 printk("     Memory Parity Error %08lx\n", *sun4c_memerr_reg);
  77         printk("REGISTER DUMP:\n");
  78         show_regs(regs);
  79         prom_halt();
  80 }
  81
  82 static void unhandled_fault(unsigned long, struct task_struct *,
  83                 struct pt_regs *) __attribute__ ((noreturn));
  84
  85 static void unhandled_fault(unsigned long address, struct task_struct *tsk,
  86                      struct pt_regs *regs)
  87 {
  88         if((unsigned long) address < PAGE_SIZE) {
  89                 printk(KERN_ALERT
  90                     "Unable to handle kernel NULL pointer dereference\n");
  91         } else {
  92                 printk(KERN_ALERT "Unable to handle kernel paging request "
  93                        "at virtual address %08lx\n", address);
  94         }
  95         printk(KERN_ALERT "tsk->{mm,active_mm}->context = %08lx\n",
  96                 (tsk->mm ? tsk->mm->context : tsk->active_mm->context));
  97         printk(KERN_ALERT "tsk->{mm,active_mm}->pgd = %08lx\n",
  98                 (tsk->mm ? (unsigned long) tsk->mm->pgd :
  99                         (unsigned long) tsk->active_mm->pgd));
 100         die_if_kernel("Oops", regs);
 101 }
 102
 103 asmlinkage int lookup_fault(unsigned long pc, unsigned long ret_pc,
 104                             unsigned long address)
 105 {
 106         struct pt_regs regs;
 107         unsigned long g2;
 108         unsigned int insn;
 109         int i;
 110
 111         i = search_extables_range(ret_pc, &g2);
 112         switch (i) {
 113         case 3:
 114                 /* load & store will be handled by fixup */
 115                 return 3;
 116
 117         case 1:
 118                 /* store will be handled by fixup, load will bump out */
 119                 /* for _to_ macros */
 120                 insn = *((unsigned int *) pc);
 121                 if ((insn >> 21) & 1)
 122                         return 1;
 123                 break;
 124
 125         case 2:
 126                 /* load will be handled by fixup, store will bump out */
 127                 /* for _from_ macros */
 128                 insn = *((unsigned int *) pc);
 129                 if (!((insn >> 21) & 1) || ((insn>>19)&0x3f) == 15)
 130                         return 2;
 131                 break;
 132
 133         default:
 134                 break;
 135         };
 136
 137         memset(&regs, 0, sizeof (regs));
 138         regs.pc = pc;
 139         regs.npc = pc + 4;
 140         __asm__ __volatile__(
 141                 "rd %%psr, %0\n\t"
 142                 "nop\n\t"
 143                 "nop\n\t"
 144                 "nop\n" : "=r" (regs.psr));
 145         unhandled_fault(address, current, &regs);
 146
 147         /* Not reached */
 148         return 0;
 149 }
 150
 151 extern unsigned long safe_compute_effective_address(struct pt_regs *,
 152                                                     unsigned int);
 153
 154 static unsigned long compute_si_addr(struct pt_regs *regs, int text_fault)
 155 {
 156         unsigned int insn;
 157
 158         if (text_fault)
 159                 return regs->pc;
 160
 161         if (regs->psr & PSR_PS) {
 162                 insn = *(unsigned int *) regs->pc;
 163         } else {
 164                 __get_user(insn, (unsigned int *) regs->pc);
 165         }
 166
 167         return safe_compute_effective_address(regs, insn);
 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         siginfo_t info;
 179         int from_user = !(regs->psr & PSR_PS);
 180         int fault;
 181
 182         if(text_fault)
 183                 address = regs->pc;
 184
 185         /*
 186          * We fault-in kernel-space virtual memory on-demand. The
 187          * 'reference' page table is init_mm.pgd.
 188          *
 189          * NOTE! We MUST NOT take any locks for this case. We may
 190          * be in an interrupt or a critical region, and should
 191          * only copy the information from the master page table,
 192          * nothing more.
 193          */
 194         if (!ARCH_SUN4C_SUN4 && address >= TASK_SIZE)
 195                 goto vmalloc_fault;
 196
 197         info.si_code = SEGV_MAPERR;
 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         down_read(&mm->mmap_sem);
 207
 208         /*
 209          * The kernel referencing a bad kernel pointer can lock up
 210          * a sun4c machine completely, so we must attempt recovery.
 211          */
 212         if(!from_user && address >= PAGE_OFFSET)
 213                 goto bad_area;
 214
 215         vma = find_vma(mm, address);
 216         if(!vma)
 217                 goto bad_area;
 218         if(vma->vm_start <= address)
 219                 goto good_area;
 220         if(!(vma->vm_flags & VM_GROWSDOWN))
 221                 goto bad_area;
 222         if(expand_stack(vma, address))
 223                 goto bad_area;
 224         /*
 225          * Ok, we have a good vm_area for this memory access, so
 226          * we can handle it..
 227          */
 228 good_area:
 229         info.si_code = SEGV_ACCERR;
 230         if(write) {
 231                 if(!(vma->vm_flags & VM_WRITE))
 232                         goto bad_area;
 233         } else {
 234                 /* Allow reads even for write-only mappings */
 235                 if(!(vma->vm_flags & (VM_READ | VM_EXEC)))
 236                         goto bad_area;
 237         }
 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, write);
 245         if (unlikely(fault & VM_FAULT_ERROR)) {
 246                 if (fault & VM_FAULT_OOM)
 247                         goto out_of_memory;
 248                 else if (fault & VM_FAULT_SIGBUS)
 249                         goto do_sigbus;
 250                 BUG();
 251         }
 252         if (fault & VM_FAULT_MAJOR)
 253                 current->maj_flt++;
 254         else
 255                 current->min_flt++;
 256         up_read(&mm->mmap_sem);
 257         return;
 258
 259         /*
 260          * Something tried to access memory that isn't in our memory map..
 261          * Fix it, but check if it's kernel or user first..
 262          */
 263 bad_area:
 264         up_read(&mm->mmap_sem);
 265
 266 bad_area_nosemaphore:
 267         /* User mode accesses just cause a SIGSEGV */
 268         if(from_user) {
 269 #if 0
 270                 printk("Fault whee %s [%d]: segfaults at %08lx pc=%08lx\n",
 271                        tsk->comm, tsk->pid, address, regs->pc);
 272 #endif
 273                 info.si_signo = SIGSEGV;
 274                 info.si_errno = 0;
 275                 /* info.si_code set above to make clear whether
 276                    this was a SEGV_MAPERR or SEGV_ACCERR fault.  */
 277                 info.si_addr = (void __user *)compute_si_addr(regs, text_fault);
 278                 info.si_trapno = 0;
 279                 force_sig_info (SIGSEGV, &info, tsk);
 280                 return;
 281         }
 282
 283         /* Is this in ex_table? */
 284 no_context:
 285         g2 = regs->u_regs[UREG_G2];
 286         if (!from_user && (fixup = search_extables_range(regs->pc, &g2))) {
 287                 if (fixup > 10) { /* Values below are reserved for other things */
 288                         extern const unsigned __memset_start[];
 289                         extern const unsigned __memset_end[];
 290                         extern const unsigned __csum_partial_copy_start[];
 291                         extern const unsigned __csum_partial_copy_end[];
 292
 293 #ifdef DEBUG_EXCEPTIONS
 294                         printk("Exception: PC<%08lx> faddr<%08lx>\n", regs->pc, address);
 295                         printk("EX_TABLE: insn<%08lx> fixup<%08x> g2<%08lx>\n",
 296                                 regs->pc, fixup, g2);
 297 #endif
 298                         if ((regs->pc >= (unsigned long)__memset_start &&
 299                              regs->pc < (unsigned long)__memset_end) ||
 300                             (regs->pc >= (unsigned long)__csum_partial_copy_start &&
 301                              regs->pc < (unsigned long)__csum_partial_copy_end)) {
 302                                 regs->u_regs[UREG_I4] = address;
 303                                 regs->u_regs[UREG_I5] = regs->pc;
 304                         }
 305                         regs->u_regs[UREG_G2] = g2;
 306                         regs->pc = fixup;
 307                         regs->npc = regs->pc + 4;
 308                         return;
 309                 }
 310         }
 311
 312         unhandled_fault (address, tsk, regs);
 313         do_exit(SIGKILL);
 314
 315 /*
 316  * We ran out of memory, or some other thing happened to us that made
 317  * us unable to handle the page fault gracefully.
 318  */
 319 out_of_memory:
 320         up_read(&mm->mmap_sem);
 321         printk("VM: killing process %s\n", tsk->comm);
 322         if (from_user)
 323                 do_group_exit(SIGKILL);
 324         goto no_context;
 325
 326 do_sigbus:
 327         up_read(&mm->mmap_sem);
 328         info.si_signo = SIGBUS;
 329         info.si_errno = 0;
 330         info.si_code = BUS_ADRERR;
 331         info.si_addr = (void __user *) compute_si_addr(regs, text_fault);
 332         info.si_trapno = 0;
 333         force_sig_info (SIGBUS, &info, tsk);
 334         if (!from_user)
 335                 goto no_context;
 336
 337 vmalloc_fault:
 338         {
 339                 /*
 340                  * Synchronize this task's top level page-table
 341                  * with the 'reference' page table.
 342                  */
 343                 int offset = pgd_index(address);
 344                 pgd_t *pgd, *pgd_k;
 345                 pmd_t *pmd, *pmd_k;
 346
 347                 pgd = tsk->active_mm->pgd + offset;
 348                 pgd_k = init_mm.pgd + offset;
 349
 350                 if (!pgd_present(*pgd)) {
 351                         if (!pgd_present(*pgd_k))
 352                                 goto bad_area_nosemaphore;
 353                         pgd_val(*pgd) = pgd_val(*pgd_k);
 354                         return;
 355                 }
 356
 357                 pmd = pmd_offset(pgd, address);
 358                 pmd_k = pmd_offset(pgd_k, address);
 359
 360                 if (pmd_present(*pmd) || !pmd_present(*pmd_k))
 361                         goto bad_area_nosemaphore;
 362                 *pmd = *pmd_k;
 363                 return;
 364         }
 365 }
 366
 367 asmlinkage void do_sun4c_fault(struct pt_regs *regs, int text_fault, int write,
 368                                unsigned long address)
 369 {
 370         extern void sun4c_update_mmu_cache(struct vm_area_struct *,
 371                                            unsigned long,pte_t);
 372         extern pte_t *sun4c_pte_offset_kernel(pmd_t *,unsigned long);
 373         struct task_struct *tsk = current;
 374         struct mm_struct *mm = tsk->mm;
 375         pgd_t *pgdp;
 376         pte_t *ptep;
 377
 378         if (text_fault) {
 379                 address = regs->pc;
 380         } else if (!write &&
 381                    !(regs->psr & PSR_PS)) {
 382                 unsigned int insn, __user *ip;
 383
 384                 ip = (unsigned int __user *)regs->pc;
 385                 if (!get_user(insn, ip)) {
 386                         if ((insn & 0xc1680000) == 0xc0680000)
 387                                 write = 1;
 388                 }
 389         }
 390
 391         if (!mm) {
 392                 /* We are oopsing. */
 393                 do_sparc_fault(regs, text_fault, write, address);
 394                 BUG();  /* P3 Oops already, you bitch */
 395         }
 396
 397         pgdp = pgd_offset(mm, address);
 398         ptep = sun4c_pte_offset_kernel((pmd_t *) pgdp, address);
 399
 400         if (pgd_val(*pgdp)) {
 401             if (write) {
 402                 if ((pte_val(*ptep) & (_SUN4C_PAGE_WRITE|_SUN4C_PAGE_PRESENT))
 403                                    == (_SUN4C_PAGE_WRITE|_SUN4C_PAGE_PRESENT)) {
 404                         unsigned long flags;
 405
 406                         *ptep = __pte(pte_val(*ptep) | _SUN4C_PAGE_ACCESSED |
 407                                       _SUN4C_PAGE_MODIFIED |
 408                                       _SUN4C_PAGE_VALID |
 409                                       _SUN4C_PAGE_DIRTY);
 410
 411                         local_irq_save(flags);
 412                         if (sun4c_get_segmap(address) != invalid_segment) {
 413                                 sun4c_put_pte(address, pte_val(*ptep));
 414                                 local_irq_restore(flags);
 415                                 return;
 416                         }
 417                         local_irq_restore(flags);
 418                 }
 419             } else {
 420                 if ((pte_val(*ptep) & (_SUN4C_PAGE_READ|_SUN4C_PAGE_PRESENT))
 421                                    == (_SUN4C_PAGE_READ|_SUN4C_PAGE_PRESENT)) {
 422                         unsigned long flags;
 423
 424                         *ptep = __pte(pte_val(*ptep) | _SUN4C_PAGE_ACCESSED |
 425                                       _SUN4C_PAGE_VALID);
 426
 427                         local_irq_save(flags);
 428                         if (sun4c_get_segmap(address) != invalid_segment) {
 429                                 sun4c_put_pte(address, pte_val(*ptep));
 430                                 local_irq_restore(flags);
 431                                 return;
 432                         }
 433                         local_irq_restore(flags);
 434                 }
 435             }
 436         }
 437
 438         /* This conditional is 'interesting'. */
 439         if (pgd_val(*pgdp) && !(write && !(pte_val(*ptep) & _SUN4C_PAGE_WRITE))
 440             && (pte_val(*ptep) & _SUN4C_PAGE_VALID))
 441                 /* Note: It is safe to not grab the MMAP semaphore here because
 442                  *       we know that update_mmu_cache() will not sleep for
 443                  *       any reason (at least not in the current implementation)
 444                  *       and therefore there is no danger of another thread getting
 445                  *       on the CPU and doing a shrink_mmap() on this vma.
 446                  */
 447                 sun4c_update_mmu_cache (find_vma(current->mm, address), address,
 448                                         *ptep);
 449         else
 450                 do_sparc_fault(regs, text_fault, write, address);
 451 }
 452
 453 /* This always deals with user addresses. */
 454 static void force_user_fault(unsigned long address, int write)
 455 {
 456         struct vm_area_struct *vma;
 457         struct task_struct *tsk = current;
 458         struct mm_struct *mm = tsk->mm;
 459         siginfo_t info;
 460
 461         info.si_code = SEGV_MAPERR;
 462
 463 #if 0
 464         printk("wf<pid=%d,wr=%d,addr=%08lx>\n",
 465                tsk->pid, write, address);
 466 #endif
 467         down_read(&mm->mmap_sem);
 468         vma = find_vma(mm, address);
 469         if(!vma)
 470                 goto bad_area;
 471         if(vma->vm_start <= address)
 472                 goto good_area;
 473         if(!(vma->vm_flags & VM_GROWSDOWN))
 474                 goto bad_area;
 475         if(expand_stack(vma, address))
 476                 goto bad_area;
 477 good_area:
 478         info.si_code = SEGV_ACCERR;
 479         if(write) {
 480                 if(!(vma->vm_flags & VM_WRITE))
 481                         goto bad_area;
 482         } else {
 483                 if(!(vma->vm_flags & (VM_READ | VM_EXEC)))
 484                         goto bad_area;
 485         }
 486         switch (handle_mm_fault(mm, vma, address, write)) {
 487         case VM_FAULT_SIGBUS:
 488         case VM_FAULT_OOM:
 489                 goto do_sigbus;
 490         }
 491         up_read(&mm->mmap_sem);
 492         return;
 493 bad_area:
 494         up_read(&mm->mmap_sem);
 495 #if 0
 496         printk("Window whee %s [%d]: segfaults at %08lx\n",
 497                tsk->comm, tsk->pid, address);
 498 #endif
 499         info.si_signo = SIGSEGV;
 500         info.si_errno = 0;
 501         /* info.si_code set above to make clear whether
 502            this was a SEGV_MAPERR or SEGV_ACCERR fault.  */
 503         info.si_addr = (void __user *) address;
 504         info.si_trapno = 0;
 505         force_sig_info (SIGSEGV, &info, tsk);
 506         return;
 507
 508 do_sigbus:
 509         up_read(&mm->mmap_sem);
 510         info.si_signo = SIGBUS;
 511         info.si_errno = 0;
 512         info.si_code = BUS_ADRERR;
 513         info.si_addr = (void __user *) address;
 514         info.si_trapno = 0;
 515         force_sig_info (SIGBUS, &info, tsk);
 516 }
 517
 518 void window_overflow_fault(void)
 519 {
 520         unsigned long sp;
 521
 522         sp = current_thread_info()->rwbuf_stkptrs[0];
 523         if(((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
 524                 force_user_fault(sp + 0x38, 1);
 525         force_user_fault(sp, 1);
 526 }
 527
 528 void window_underflow_fault(unsigned long sp)
 529 {
 530         if(((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
 531                 force_user_fault(sp + 0x38, 0);
 532         force_user_fault(sp, 0);
 533 }
 534
 535 void window_ret_fault(struct pt_regs *regs)
 536 {
 537         unsigned long sp;
 538
 539         sp = regs->u_regs[UREG_FP];
 540         if(((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
 541                 force_user_fault(sp + 0x38, 0);
 542         force_user_fault(sp, 0);
 543 }