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   1 /* $Id: fault.c,v 1.122 2001/11/17 07:19:26 davem Exp $
   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 /* Nice, simple, prom library does all the sweating for us. ;) */
  51 int prom_probe_memory (void)
  52 {
  53         register struct linux_mlist_v0 *mlist;
  54         register unsigned long bytes, base_paddr, tally;
  55         register int i;
  56
  57         i = 0;
  58         mlist= *prom_meminfo()->v0_available;
  59         bytes = tally = mlist->num_bytes;
  60         base_paddr = (unsigned long) mlist->start_adr;
  61
  62         sp_banks[0].base_addr = base_paddr;
  63         sp_banks[0].num_bytes = bytes;
  64
  65         while (mlist->theres_more != (void *) 0){
  66                 i++;
  67                 mlist = mlist->theres_more;
  68                 bytes = mlist->num_bytes;
  69                 tally += bytes;
  70                 if (i > SPARC_PHYS_BANKS-1) {
  71                         printk ("The machine has more banks than "
  72                                 "this kernel can support\n"
  73                                 "Increase the SPARC_PHYS_BANKS "
  74                                 "setting (currently %d)\n",
  75                                 SPARC_PHYS_BANKS);
  76                         i = SPARC_PHYS_BANKS-1;
  77                         break;
  78                 }
  79
  80                 sp_banks[i].base_addr = (unsigned long) mlist->start_adr;
  81                 sp_banks[i].num_bytes = mlist->num_bytes;
  82         }
  83
  84         i++;
  85         sp_banks[i].base_addr = 0xdeadbeef;
  86         sp_banks[i].num_bytes = 0;
  87
  88         /* Now mask all bank sizes on a page boundary, it is all we can
  89          * use anyways.
  90          */
  91         for(i=0; sp_banks[i].num_bytes != 0; i++)
  92                 sp_banks[i].num_bytes &= PAGE_MASK;
  93
  94         return tally;
  95 }
  96
  97 /* Traverse the memory lists in the prom to see how much physical we
  98  * have.
  99  */
 100 unsigned long
 101 probe_memory(void)
 102 {
 103         int total;
 104
 105         total = prom_probe_memory();
 106
 107         /* Oh man, much nicer, keep the dirt in promlib. */
 108         return total;
 109 }
 110
 111 extern void sun4c_complete_all_stores(void);
 112
 113 /* Whee, a level 15 NMI interrupt memory error.  Let's have fun... */
 114 asmlinkage void sparc_lvl15_nmi(struct pt_regs *regs, unsigned long serr,
 115                                 unsigned long svaddr, unsigned long aerr,
 116                                 unsigned long avaddr)
 117 {
 118         sun4c_complete_all_stores();
 119         printk("FAULT: NMI received\n");
 120         printk("SREGS: Synchronous Error %08lx\n", serr);
 121         printk("       Synchronous Vaddr %08lx\n", svaddr);
 122         printk("      Asynchronous Error %08lx\n", aerr);
 123         printk("      Asynchronous Vaddr %08lx\n", avaddr);
 124         if (sun4c_memerr_reg)
 125                 printk("     Memory Parity Error %08lx\n", *sun4c_memerr_reg);
 126         printk("REGISTER DUMP:\n");
 127         show_regs(regs);
 128         prom_halt();
 129 }
 130
 131 static void unhandled_fault(unsigned long, struct task_struct *,
 132                 struct pt_regs *) __attribute__ ((noreturn));
 133
 134 static void unhandled_fault(unsigned long address, struct task_struct *tsk,
 135                      struct pt_regs *regs)
 136 {
 137         if((unsigned long) address < PAGE_SIZE) {
 138                 printk(KERN_ALERT
 139                     "Unable to handle kernel NULL pointer dereference\n");
 140         } else {
 141                 printk(KERN_ALERT "Unable to handle kernel paging request "
 142                        "at virtual address %08lx\n", address);
 143         }
 144         printk(KERN_ALERT "tsk->{mm,active_mm}->context = %08lx\n",
 145                 (tsk->mm ? tsk->mm->context : tsk->active_mm->context));
 146         printk(KERN_ALERT "tsk->{mm,active_mm}->pgd = %08lx\n",
 147                 (tsk->mm ? (unsigned long) tsk->mm->pgd :
 148                         (unsigned long) tsk->active_mm->pgd));
 149         die_if_kernel("Oops", regs);
 150 }
 151
 152 asmlinkage int lookup_fault(unsigned long pc, unsigned long ret_pc,
 153                             unsigned long address)
 154 {
 155         struct pt_regs regs;
 156         unsigned long g2;
 157         unsigned int insn;
 158         int i;
 159
 160         i = search_extables_range(ret_pc, &g2);
 161         switch (i) {
 162         case 3:
 163                 /* load & store will be handled by fixup */
 164                 return 3;
 165
 166         case 1:
 167                 /* store will be handled by fixup, load will bump out */
 168                 /* for _to_ macros */
 169                 insn = *((unsigned int *) pc);
 170                 if ((insn >> 21) & 1)
 171                         return 1;
 172                 break;
 173
 174         case 2:
 175                 /* load will be handled by fixup, store will bump out */
 176                 /* for _from_ macros */
 177                 insn = *((unsigned int *) pc);
 178                 if (!((insn >> 21) & 1) || ((insn>>19)&0x3f) == 15)
 179                         return 2;
 180                 break;
 181
 182         default:
 183                 break;
 184         };
 185
 186         memset(&regs, 0, sizeof (regs));
 187         regs.pc = pc;
 188         regs.npc = pc + 4;
 189         __asm__ __volatile__(
 190                 "rd %%psr, %0\n\t"
 191                 "nop\n\t"
 192                 "nop\n\t"
 193                 "nop\n" : "=r" (regs.psr));
 194         unhandled_fault(address, current, &regs);
 195
 196         /* Not reached */
 197         return 0;
 198 }
 199
 200 extern unsigned long safe_compute_effective_address(struct pt_regs *,
 201                                                     unsigned int);
 202
 203 static unsigned long compute_si_addr(struct pt_regs *regs, int text_fault)
 204 {
 205         unsigned int insn;
 206
 207         if (text_fault)
 208                 return regs->pc;
 209
 210         if (regs->psr & PSR_PS) {
 211                 insn = *(unsigned int *) regs->pc;
 212         } else {
 213                 __get_user(insn, (unsigned int *) regs->pc);
 214         }
 215
 216         return safe_compute_effective_address(regs, insn);
 217 }
 218
 219 asmlinkage void do_sparc_fault(struct pt_regs *regs, int text_fault, int write,
 220                                unsigned long address)
 221 {
 222         struct vm_area_struct *vma;
 223         struct task_struct *tsk = current;
 224         struct mm_struct *mm = tsk->mm;
 225         unsigned int fixup;
 226         unsigned long g2;
 227         siginfo_t info;
 228         int from_user = !(regs->psr & PSR_PS);
 229         int fault;
 230
 231         if(text_fault)
 232                 address = regs->pc;
 233
 234         /*
 235          * We fault-in kernel-space virtual memory on-demand. The
 236          * 'reference' page table is init_mm.pgd.
 237          *
 238          * NOTE! We MUST NOT take any locks for this case. We may
 239          * be in an interrupt or a critical region, and should
 240          * only copy the information from the master page table,
 241          * nothing more.
 242          */
 243         if (!ARCH_SUN4C_SUN4 && address >= TASK_SIZE)
 244                 goto vmalloc_fault;
 245
 246         info.si_code = SEGV_MAPERR;
 247
 248         /*
 249          * If we're in an interrupt or have no user
 250          * context, we must not take the fault..
 251          */
 252         if (in_atomic() || !mm)
 253                 goto no_context;
 254
 255         down_read(&mm->mmap_sem);
 256
 257         /*
 258          * The kernel referencing a bad kernel pointer can lock up
 259          * a sun4c machine completely, so we must attempt recovery.
 260          */
 261         if(!from_user && address >= PAGE_OFFSET)
 262                 goto bad_area;
 263
 264         vma = find_vma(mm, address);
 265         if(!vma)
 266                 goto bad_area;
 267         if(vma->vm_start <= address)
 268                 goto good_area;
 269         if(!(vma->vm_flags & VM_GROWSDOWN))
 270                 goto bad_area;
 271         if(expand_stack(vma, address))
 272                 goto bad_area;
 273         /*
 274          * Ok, we have a good vm_area for this memory access, so
 275          * we can handle it..
 276          */
 277 good_area:
 278         info.si_code = SEGV_ACCERR;
 279         if(write) {
 280                 if(!(vma->vm_flags & VM_WRITE))
 281                         goto bad_area;
 282         } else {
 283                 /* Allow reads even for write-only mappings */
 284                 if(!(vma->vm_flags & (VM_READ | VM_EXEC)))
 285                         goto bad_area;
 286         }
 287
 288         /*
 289          * If for any reason at all we couldn't handle the fault,
 290          * make sure we exit gracefully rather than endlessly redo
 291          * the fault.
 292          */
 293         fault = handle_mm_fault(mm, vma, address, write);
 294         if (unlikely(fault & VM_FAULT_ERROR)) {
 295                 if (fault & VM_FAULT_OOM)
 296                         goto out_of_memory;
 297                 else if (fault & VM_FAULT_SIGBUS)
 298                         goto do_sigbus;
 299                 BUG();
 300         }
 301         if (fault & VM_FAULT_MAJOR)
 302                 current->maj_flt++;
 303         else
 304                 current->min_flt++;
 305         up_read(&mm->mmap_sem);
 306         return;
 307
 308         /*
 309          * Something tried to access memory that isn't in our memory map..
 310          * Fix it, but check if it's kernel or user first..
 311          */
 312 bad_area:
 313         up_read(&mm->mmap_sem);
 314
 315 bad_area_nosemaphore:
 316         /* User mode accesses just cause a SIGSEGV */
 317         if(from_user) {
 318 #if 0
 319                 printk("Fault whee %s [%d]: segfaults at %08lx pc=%08lx\n",
 320                        tsk->comm, tsk->pid, address, regs->pc);
 321 #endif
 322                 info.si_signo = SIGSEGV;
 323                 info.si_errno = 0;
 324                 /* info.si_code set above to make clear whether
 325                    this was a SEGV_MAPERR or SEGV_ACCERR fault.  */
 326                 info.si_addr = (void __user *)compute_si_addr(regs, text_fault);
 327                 info.si_trapno = 0;
 328                 force_sig_info (SIGSEGV, &info, tsk);
 329                 return;
 330         }
 331
 332         /* Is this in ex_table? */
 333 no_context:
 334         g2 = regs->u_regs[UREG_G2];
 335         if (!from_user && (fixup = search_extables_range(regs->pc, &g2))) {
 336                 if (fixup > 10) { /* Values below are reserved for other things */
 337                         extern const unsigned __memset_start[];
 338                         extern const unsigned __memset_end[];
 339                         extern const unsigned __csum_partial_copy_start[];
 340                         extern const unsigned __csum_partial_copy_end[];
 341
 342 #ifdef DEBUG_EXCEPTIONS
 343                         printk("Exception: PC<%08lx> faddr<%08lx>\n", regs->pc, address);
 344                         printk("EX_TABLE: insn<%08lx> fixup<%08x> g2<%08lx>\n",
 345                                 regs->pc, fixup, g2);
 346 #endif
 347                         if ((regs->pc >= (unsigned long)__memset_start &&
 348                              regs->pc < (unsigned long)__memset_end) ||
 349                             (regs->pc >= (unsigned long)__csum_partial_copy_start &&
 350                              regs->pc < (unsigned long)__csum_partial_copy_end)) {
 351                                 regs->u_regs[UREG_I4] = address;
 352                                 regs->u_regs[UREG_I5] = regs->pc;
 353                         }
 354                         regs->u_regs[UREG_G2] = g2;
 355                         regs->pc = fixup;
 356                         regs->npc = regs->pc + 4;
 357                         return;
 358                 }
 359         }
 360
 361         unhandled_fault (address, tsk, regs);
 362         do_exit(SIGKILL);
 363
 364 /*
 365  * We ran out of memory, or some other thing happened to us that made
 366  * us unable to handle the page fault gracefully.
 367  */
 368 out_of_memory:
 369         up_read(&mm->mmap_sem);
 370         printk("VM: killing process %s\n", tsk->comm);
 371         if (from_user)
 372                 do_group_exit(SIGKILL);
 373         goto no_context;
 374
 375 do_sigbus:
 376         up_read(&mm->mmap_sem);
 377         info.si_signo = SIGBUS;
 378         info.si_errno = 0;
 379         info.si_code = BUS_ADRERR;
 380         info.si_addr = (void __user *) compute_si_addr(regs, text_fault);
 381         info.si_trapno = 0;
 382         force_sig_info (SIGBUS, &info, tsk);
 383         if (!from_user)
 384                 goto no_context;
 385
 386 vmalloc_fault:
 387         {
 388                 /*
 389                  * Synchronize this task's top level page-table
 390                  * with the 'reference' page table.
 391                  */
 392                 int offset = pgd_index(address);
 393                 pgd_t *pgd, *pgd_k;
 394                 pmd_t *pmd, *pmd_k;
 395
 396                 pgd = tsk->active_mm->pgd + offset;
 397                 pgd_k = init_mm.pgd + offset;
 398
 399                 if (!pgd_present(*pgd)) {
 400                         if (!pgd_present(*pgd_k))
 401                                 goto bad_area_nosemaphore;
 402                         pgd_val(*pgd) = pgd_val(*pgd_k);
 403                         return;
 404                 }
 405
 406                 pmd = pmd_offset(pgd, address);
 407                 pmd_k = pmd_offset(pgd_k, address);
 408
 409                 if (pmd_present(*pmd) || !pmd_present(*pmd_k))
 410                         goto bad_area_nosemaphore;
 411                 *pmd = *pmd_k;
 412                 return;
 413         }
 414 }
 415
 416 asmlinkage void do_sun4c_fault(struct pt_regs *regs, int text_fault, int write,
 417                                unsigned long address)
 418 {
 419         extern void sun4c_update_mmu_cache(struct vm_area_struct *,
 420                                            unsigned long,pte_t);
 421         extern pte_t *sun4c_pte_offset_kernel(pmd_t *,unsigned long);
 422         struct task_struct *tsk = current;
 423         struct mm_struct *mm = tsk->mm;
 424         pgd_t *pgdp;
 425         pte_t *ptep;
 426
 427         if (text_fault) {
 428                 address = regs->pc;
 429         } else if (!write &&
 430                    !(regs->psr & PSR_PS)) {
 431                 unsigned int insn, __user *ip;
 432
 433                 ip = (unsigned int __user *)regs->pc;
 434                 if (!get_user(insn, ip)) {
 435                         if ((insn & 0xc1680000) == 0xc0680000)
 436                                 write = 1;
 437                 }
 438         }
 439
 440         if (!mm) {
 441                 /* We are oopsing. */
 442                 do_sparc_fault(regs, text_fault, write, address);
 443                 BUG();  /* P3 Oops already, you bitch */
 444         }
 445
 446         pgdp = pgd_offset(mm, address);
 447         ptep = sun4c_pte_offset_kernel((pmd_t *) pgdp, address);
 448
 449         if (pgd_val(*pgdp)) {
 450             if (write) {
 451                 if ((pte_val(*ptep) & (_SUN4C_PAGE_WRITE|_SUN4C_PAGE_PRESENT))
 452                                    == (_SUN4C_PAGE_WRITE|_SUN4C_PAGE_PRESENT)) {
 453                         unsigned long flags;
 454
 455                         *ptep = __pte(pte_val(*ptep) | _SUN4C_PAGE_ACCESSED |
 456                                       _SUN4C_PAGE_MODIFIED |
 457                                       _SUN4C_PAGE_VALID |
 458                                       _SUN4C_PAGE_DIRTY);
 459
 460                         local_irq_save(flags);
 461                         if (sun4c_get_segmap(address) != invalid_segment) {
 462                                 sun4c_put_pte(address, pte_val(*ptep));
 463                                 local_irq_restore(flags);
 464                                 return;
 465                         }
 466                         local_irq_restore(flags);
 467                 }
 468             } else {
 469                 if ((pte_val(*ptep) & (_SUN4C_PAGE_READ|_SUN4C_PAGE_PRESENT))
 470                                    == (_SUN4C_PAGE_READ|_SUN4C_PAGE_PRESENT)) {
 471                         unsigned long flags;
 472
 473                         *ptep = __pte(pte_val(*ptep) | _SUN4C_PAGE_ACCESSED |
 474                                       _SUN4C_PAGE_VALID);
 475
 476                         local_irq_save(flags);
 477                         if (sun4c_get_segmap(address) != invalid_segment) {
 478                                 sun4c_put_pte(address, pte_val(*ptep));
 479                                 local_irq_restore(flags);
 480                                 return;
 481                         }
 482                         local_irq_restore(flags);
 483                 }
 484             }
 485         }
 486
 487         /* This conditional is 'interesting'. */
 488         if (pgd_val(*pgdp) && !(write && !(pte_val(*ptep) & _SUN4C_PAGE_WRITE))
 489             && (pte_val(*ptep) & _SUN4C_PAGE_VALID))
 490                 /* Note: It is safe to not grab the MMAP semaphore here because
 491                  *       we know that update_mmu_cache() will not sleep for
 492                  *       any reason (at least not in the current implementation)
 493                  *       and therefore there is no danger of another thread getting
 494                  *       on the CPU and doing a shrink_mmap() on this vma.
 495                  */
 496                 sun4c_update_mmu_cache (find_vma(current->mm, address), address,
 497                                         *ptep);
 498         else
 499                 do_sparc_fault(regs, text_fault, write, address);
 500 }
 501
 502 /* This always deals with user addresses. */
 503 inline void force_user_fault(unsigned long address, int write)
 504 {
 505         struct vm_area_struct *vma;
 506         struct task_struct *tsk = current;
 507         struct mm_struct *mm = tsk->mm;
 508         siginfo_t info;
 509
 510         info.si_code = SEGV_MAPERR;
 511
 512 #if 0
 513         printk("wf<pid=%d,wr=%d,addr=%08lx>\n",
 514                tsk->pid, write, address);
 515 #endif
 516         down_read(&mm->mmap_sem);
 517         vma = find_vma(mm, address);
 518         if(!vma)
 519                 goto bad_area;
 520         if(vma->vm_start <= address)
 521                 goto good_area;
 522         if(!(vma->vm_flags & VM_GROWSDOWN))
 523                 goto bad_area;
 524         if(expand_stack(vma, address))
 525                 goto bad_area;
 526 good_area:
 527         info.si_code = SEGV_ACCERR;
 528         if(write) {
 529                 if(!(vma->vm_flags & VM_WRITE))
 530                         goto bad_area;
 531         } else {
 532                 if(!(vma->vm_flags & (VM_READ | VM_EXEC)))
 533                         goto bad_area;
 534         }
 535         switch (handle_mm_fault(mm, vma, address, write)) {
 536         case VM_FAULT_SIGBUS:
 537         case VM_FAULT_OOM:
 538                 goto do_sigbus;
 539         }
 540         up_read(&mm->mmap_sem);
 541         return;
 542 bad_area:
 543         up_read(&mm->mmap_sem);
 544 #if 0
 545         printk("Window whee %s [%d]: segfaults at %08lx\n",
 546                tsk->comm, tsk->pid, address);
 547 #endif
 548         info.si_signo = SIGSEGV;
 549         info.si_errno = 0;
 550         /* info.si_code set above to make clear whether
 551            this was a SEGV_MAPERR or SEGV_ACCERR fault.  */
 552         info.si_addr = (void __user *) address;
 553         info.si_trapno = 0;
 554         force_sig_info (SIGSEGV, &info, tsk);
 555         return;
 556
 557 do_sigbus:
 558         up_read(&mm->mmap_sem);
 559         info.si_signo = SIGBUS;
 560         info.si_errno = 0;
 561         info.si_code = BUS_ADRERR;
 562         info.si_addr = (void __user *) address;
 563         info.si_trapno = 0;
 564         force_sig_info (SIGBUS, &info, tsk);
 565 }
 566
 567 void window_overflow_fault(void)
 568 {
 569         unsigned long sp;
 570
 571         sp = current_thread_info()->rwbuf_stkptrs[0];
 572         if(((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
 573                 force_user_fault(sp + 0x38, 1);
 574         force_user_fault(sp, 1);
 575 }
 576
 577 void window_underflow_fault(unsigned long sp)
 578 {
 579         if(((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
 580                 force_user_fault(sp + 0x38, 0);
 581         force_user_fault(sp, 0);
 582 }
 583
 584 void window_ret_fault(struct pt_regs *regs)
 585 {
 586         unsigned long sp;
 587
 588         sp = regs->u_regs[UREG_FP];
 589         if(((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
 590                 force_user_fault(sp + 0x38, 0);
 591         force_user_fault(sp, 0);
 592 }