arch/sparc/mm/fault.c

   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/smp_lock.h>
  22 #include <linux/interrupt.h>
  23 #include <linux/module.h>
  24 #include <linux/kdebug.h>
  25
  26 #include <asm/system.h>
  27 #include <asm/page.h>
  28 #include <asm/pgtable.h>
  29 #include <asm/memreg.h>
  30 #include <asm/openprom.h>
  31 #include <asm/oplib.h>
  32 #include <asm/smp.h>
  33 #include <asm/traps.h>
  34 #include <asm/uaccess.h>
  35
  36 extern int prom_node_root;
  37
  38 /* At boot time we determine these two values necessary for setting
  39  * up the segment maps and page table entries (pte's).
  40  */
  41
  42 int num_segmaps, num_contexts;
  43 int invalid_segment;
  44
  45 /* various Virtual Address Cache parameters we find at boot time... */
  46
  47 int vac_size, vac_linesize, vac_do_hw_vac_flushes;
  48 int vac_entries_per_context, vac_entries_per_segment;
  49 int vac_entries_per_page;
  50
  51 /* Nice, simple, prom library does all the sweating for us. ;) */
  52 int prom_probe_memory (void)
  53 {
  54         register struct linux_mlist_v0 *mlist;
  55         register unsigned long bytes, base_paddr, tally;
  56         register int i;
  57
  58         i = 0;
  59         mlist= *prom_meminfo()->v0_available;
  60         bytes = tally = mlist->num_bytes;
  61         base_paddr = (unsigned long) mlist->start_adr;
  62
  63         sp_banks[0].base_addr = base_paddr;
  64         sp_banks[0].num_bytes = bytes;
  65
  66         while (mlist->theres_more != (void *) 0){
  67                 i++;
  68                 mlist = mlist->theres_more;
  69                 bytes = mlist->num_bytes;
  70                 tally += bytes;
  71                 if (i > SPARC_PHYS_BANKS-1) {
  72                         printk ("The machine has more banks than "
  73                                 "this kernel can support\n"
  74                                 "Increase the SPARC_PHYS_BANKS "
  75                                 "setting (currently %d)\n",
  76                                 SPARC_PHYS_BANKS);
  77                         i = SPARC_PHYS_BANKS-1;
  78                         break;
  79                 }
  80
  81                 sp_banks[i].base_addr = (unsigned long) mlist->start_adr;
  82                 sp_banks[i].num_bytes = mlist->num_bytes;
  83         }
  84
  85         i++;
  86         sp_banks[i].base_addr = 0xdeadbeef;
  87         sp_banks[i].num_bytes = 0;
  88
  89         /* Now mask all bank sizes on a page boundary, it is all we can
  90          * use anyways.
  91          */
  92         for(i=0; sp_banks[i].num_bytes != 0; i++)
  93                 sp_banks[i].num_bytes &= PAGE_MASK;
  94
  95         return tally;
  96 }
  97
  98 /* Traverse the memory lists in the prom to see how much physical we
  99  * have.
 100  */
 101 unsigned long
 102 probe_memory(void)
 103 {
 104         int total;
 105
 106         total = prom_probe_memory();
 107
 108         /* Oh man, much nicer, keep the dirt in promlib. */
 109         return total;
 110 }
 111
 112 extern void sun4c_complete_all_stores(void);
 113
 114 /* Whee, a level 15 NMI interrupt memory error.  Let's have fun... */
 115 asmlinkage void sparc_lvl15_nmi(struct pt_regs *regs, unsigned long serr,
 116                                 unsigned long svaddr, unsigned long aerr,
 117                                 unsigned long avaddr)
 118 {
 119         sun4c_complete_all_stores();
 120         printk("FAULT: NMI received\n");
 121         printk("SREGS: Synchronous Error %08lx\n", serr);
 122         printk("       Synchronous Vaddr %08lx\n", svaddr);
 123         printk("      Asynchronous Error %08lx\n", aerr);
 124         printk("      Asynchronous Vaddr %08lx\n", avaddr);
 125         if (sun4c_memerr_reg)
 126                 printk("     Memory Parity Error %08lx\n", *sun4c_memerr_reg);
 127         printk("REGISTER DUMP:\n");
 128         show_regs(regs);
 129         prom_halt();
 130 }
 131
 132 static void unhandled_fault(unsigned long, struct task_struct *,
 133                 struct pt_regs *) __attribute__ ((noreturn));
 134
 135 static void unhandled_fault(unsigned long address, struct task_struct *tsk,
 136                      struct pt_regs *regs)
 137 {
 138         if((unsigned long) address < PAGE_SIZE) {
 139                 printk(KERN_ALERT
 140                     "Unable to handle kernel NULL pointer dereference\n");
 141         } else {
 142                 printk(KERN_ALERT "Unable to handle kernel paging request "
 143                        "at virtual address %08lx\n", address);
 144         }
 145         printk(KERN_ALERT "tsk->{mm,active_mm}->context = %08lx\n",
 146                 (tsk->mm ? tsk->mm->context : tsk->active_mm->context));
 147         printk(KERN_ALERT "tsk->{mm,active_mm}->pgd = %08lx\n",
 148                 (tsk->mm ? (unsigned long) tsk->mm->pgd :
 149                         (unsigned long) tsk->active_mm->pgd));
 150         die_if_kernel("Oops", regs);
 151 }
 152
 153 asmlinkage int lookup_fault(unsigned long pc, unsigned long ret_pc,
 154                             unsigned long address)
 155 {
 156         struct pt_regs regs;
 157         unsigned long g2;
 158         unsigned int insn;
 159         int i;
 160
 161         i = search_extables_range(ret_pc, &g2);
 162         switch (i) {
 163         case 3:
 164                 /* load & store will be handled by fixup */
 165                 return 3;
 166
 167         case 1:
 168                 /* store will be handled by fixup, load will bump out */
 169                 /* for _to_ macros */
 170                 insn = *((unsigned int *) pc);
 171                 if ((insn >> 21) & 1)
 172                         return 1;
 173                 break;
 174
 175         case 2:
 176                 /* load will be handled by fixup, store will bump out */
 177                 /* for _from_ macros */
 178                 insn = *((unsigned int *) pc);
 179                 if (!((insn >> 21) & 1) || ((insn>>19)&0x3f) == 15)
 180                         return 2;
 181                 break;
 182
 183         default:
 184                 break;
 185         };
 186
 187         memset(&regs, 0, sizeof (regs));
 188         regs.pc = pc;
 189         regs.npc = pc + 4;
 190         __asm__ __volatile__(
 191                 "rd %%psr, %0\n\t"
 192                 "nop\n\t"
 193                 "nop\n\t"
 194                 "nop\n" : "=r" (regs.psr));
 195         unhandled_fault(address, current, &regs);
 196
 197         /* Not reached */
 198         return 0;
 199 }
 200
 201 extern unsigned long safe_compute_effective_address(struct pt_regs *,
 202                                                     unsigned int);
 203
 204 static unsigned long compute_si_addr(struct pt_regs *regs, int text_fault)
 205 {
 206         unsigned int insn;
 207
 208         if (text_fault)
 209                 return regs->pc;
 210
 211         if (regs->psr & PSR_PS) {
 212                 insn = *(unsigned int *) regs->pc;
 213         } else {
 214                 __get_user(insn, (unsigned int *) regs->pc);
 215         }
 216
 217         return safe_compute_effective_address(regs, insn);
 218 }
 219
 220 asmlinkage void do_sparc_fault(struct pt_regs *regs, int text_fault, int write,
 221                                unsigned long address)
 222 {
 223         struct vm_area_struct *vma;
 224         struct task_struct *tsk = current;
 225         struct mm_struct *mm = tsk->mm;
 226         unsigned int fixup;
 227         unsigned long g2;
 228         siginfo_t info;
 229         int from_user = !(regs->psr & PSR_PS);
 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         switch (handle_mm_fault(mm, vma, address, write)) {
 294         case VM_FAULT_SIGBUS:
 295                 goto do_sigbus;
 296         case VM_FAULT_OOM:
 297                 goto out_of_memory;
 298         case VM_FAULT_MAJOR:
 299                 current->maj_flt++;
 300                 break;
 301         case VM_FAULT_MINOR:
 302         default:
 303                 current->min_flt++;
 304                 break;
 305         }
 306         up_read(&mm->mmap_sem);
 307         return;
 308
 309         /*
 310          * Something tried to access memory that isn't in our memory map..
 311          * Fix it, but check if it's kernel or user first..
 312          */
 313 bad_area:
 314         up_read(&mm->mmap_sem);
 315
 316 bad_area_nosemaphore:
 317         /* User mode accesses just cause a SIGSEGV */
 318         if(from_user) {
 319 #if 0
 320                 printk("Fault whee %s [%d]: segfaults at %08lx pc=%08lx\n",
 321                        tsk->comm, tsk->pid, address, regs->pc);
 322 #endif
 323                 info.si_signo = SIGSEGV;
 324                 info.si_errno = 0;
 325                 /* info.si_code set above to make clear whether
 326                    this was a SEGV_MAPERR or SEGV_ACCERR fault.  */
 327                 info.si_addr = (void __user *)compute_si_addr(regs, text_fault);
 328                 info.si_trapno = 0;
 329                 force_sig_info (SIGSEGV, &info, tsk);
 330                 return;
 331         }
 332
 333         /* Is this in ex_table? */
 334 no_context:
 335         g2 = regs->u_regs[UREG_G2];
 336         if (!from_user && (fixup = search_extables_range(regs->pc, &g2))) {
 337                 if (fixup > 10) { /* Values below are reserved for other things */
 338                         extern const unsigned __memset_start[];
 339                         extern const unsigned __memset_end[];
 340                         extern const unsigned __csum_partial_copy_start[];
 341                         extern const unsigned __csum_partial_copy_end[];
 342
 343 #ifdef DEBUG_EXCEPTIONS
 344                         printk("Exception: PC<%08lx> faddr<%08lx>\n", regs->pc, address);
 345                         printk("EX_TABLE: insn<%08lx> fixup<%08x> g2<%08lx>\n",
 346                                 regs->pc, fixup, g2);
 347 #endif
 348                         if ((regs->pc >= (unsigned long)__memset_start &&
 349                              regs->pc < (unsigned long)__memset_end) ||
 350                             (regs->pc >= (unsigned long)__csum_partial_copy_start &&
 351                              regs->pc < (unsigned long)__csum_partial_copy_end)) {
 352                                 regs->u_regs[UREG_I4] = address;
 353                                 regs->u_regs[UREG_I5] = regs->pc;
 354                         }
 355                         regs->u_regs[UREG_G2] = g2;
 356                         regs->pc = fixup;
 357                         regs->npc = regs->pc + 4;
 358                         return;
 359                 }
 360         }
 361
 362         unhandled_fault (address, tsk, regs);
 363         do_exit(SIGKILL);
 364
 365 /*
 366  * We ran out of memory, or some other thing happened to us that made
 367  * us unable to handle the page fault gracefully.
 368  */
 369 out_of_memory:
 370         up_read(&mm->mmap_sem);
 371         printk("VM: killing process %s\n", tsk->comm);
 372         if (from_user)
 373                 do_exit(SIGKILL);
 374         goto no_context;
 375
 376 do_sigbus:
 377         up_read(&mm->mmap_sem);
 378         info.si_signo = SIGBUS;
 379         info.si_errno = 0;
 380         info.si_code = BUS_ADRERR;
 381         info.si_addr = (void __user *) compute_si_addr(regs, text_fault);
 382         info.si_trapno = 0;
 383         force_sig_info (SIGBUS, &info, tsk);
 384         if (!from_user)
 385                 goto no_context;
 386
 387 vmalloc_fault:
 388         {
 389                 /*
 390                  * Synchronize this task's top level page-table
 391                  * with the 'reference' page table.
 392                  */
 393                 int offset = pgd_index(address);
 394                 pgd_t *pgd, *pgd_k;
 395                 pmd_t *pmd, *pmd_k;
 396
 397                 pgd = tsk->active_mm->pgd + offset;
 398                 pgd_k = init_mm.pgd + offset;
 399
 400                 if (!pgd_present(*pgd)) {
 401                         if (!pgd_present(*pgd_k))
 402                                 goto bad_area_nosemaphore;
 403                         pgd_val(*pgd) = pgd_val(*pgd_k);
 404                         return;
 405                 }
 406
 407                 pmd = pmd_offset(pgd, address);
 408                 pmd_k = pmd_offset(pgd_k, address);
 409
 410                 if (pmd_present(*pmd) || !pmd_present(*pmd_k))
 411                         goto bad_area_nosemaphore;
 412                 *pmd = *pmd_k;
 413                 return;
 414         }
 415 }
 416
 417 asmlinkage void do_sun4c_fault(struct pt_regs *regs, int text_fault, int write,
 418                                unsigned long address)
 419 {
 420         extern void sun4c_update_mmu_cache(struct vm_area_struct *,
 421                                            unsigned long,pte_t);
 422         extern pte_t *sun4c_pte_offset_kernel(pmd_t *,unsigned long);
 423         struct task_struct *tsk = current;
 424         struct mm_struct *mm = tsk->mm;
 425         pgd_t *pgdp;
 426         pte_t *ptep;
 427
 428         if (text_fault) {
 429                 address = regs->pc;
 430         } else if (!write &&
 431                    !(regs->psr & PSR_PS)) {
 432                 unsigned int insn, __user *ip;
 433
 434                 ip = (unsigned int __user *)regs->pc;
 435                 if (!get_user(insn, ip)) {
 436                         if ((insn & 0xc1680000) == 0xc0680000)
 437                                 write = 1;
 438                 }
 439         }
 440
 441         if (!mm) {
 442                 /* We are oopsing. */
 443                 do_sparc_fault(regs, text_fault, write, address);
 444                 BUG();  /* P3 Oops already, you bitch */
 445         }
 446
 447         pgdp = pgd_offset(mm, address);
 448         ptep = sun4c_pte_offset_kernel((pmd_t *) pgdp, address);
 449
 450         if (pgd_val(*pgdp)) {
 451             if (write) {
 452                 if ((pte_val(*ptep) & (_SUN4C_PAGE_WRITE|_SUN4C_PAGE_PRESENT))
 453                                    == (_SUN4C_PAGE_WRITE|_SUN4C_PAGE_PRESENT)) {
 454                         unsigned long flags;
 455
 456                         *ptep = __pte(pte_val(*ptep) | _SUN4C_PAGE_ACCESSED |
 457                                       _SUN4C_PAGE_MODIFIED |
 458                                       _SUN4C_PAGE_VALID |
 459                                       _SUN4C_PAGE_DIRTY);
 460
 461                         local_irq_save(flags);
 462                         if (sun4c_get_segmap(address) != invalid_segment) {
 463                                 sun4c_put_pte(address, pte_val(*ptep));
 464                                 local_irq_restore(flags);
 465                                 return;
 466                         }
 467                         local_irq_restore(flags);
 468                 }
 469             } else {
 470                 if ((pte_val(*ptep) & (_SUN4C_PAGE_READ|_SUN4C_PAGE_PRESENT))
 471                                    == (_SUN4C_PAGE_READ|_SUN4C_PAGE_PRESENT)) {
 472                         unsigned long flags;
 473
 474                         *ptep = __pte(pte_val(*ptep) | _SUN4C_PAGE_ACCESSED |
 475                                       _SUN4C_PAGE_VALID);
 476
 477                         local_irq_save(flags);
 478                         if (sun4c_get_segmap(address) != invalid_segment) {
 479                                 sun4c_put_pte(address, pte_val(*ptep));
 480                                 local_irq_restore(flags);
 481                                 return;
 482                         }
 483                         local_irq_restore(flags);
 484                 }
 485             }
 486         }
 487
 488         /* This conditional is 'interesting'. */
 489         if (pgd_val(*pgdp) && !(write && !(pte_val(*ptep) & _SUN4C_PAGE_WRITE))
 490             && (pte_val(*ptep) & _SUN4C_PAGE_VALID))
 491                 /* Note: It is safe to not grab the MMAP semaphore here because
 492                  *       we know that update_mmu_cache() will not sleep for
 493                  *       any reason (at least not in the current implementation)
 494                  *       and therefore there is no danger of another thread getting
 495                  *       on the CPU and doing a shrink_mmap() on this vma.
 496                  */
 497                 sun4c_update_mmu_cache (find_vma(current->mm, address), address,
 498                                         *ptep);
 499         else
 500                 do_sparc_fault(regs, text_fault, write, address);
 501 }
 502
 503 /* This always deals with user addresses. */
 504 inline void force_user_fault(unsigned long address, int write)
 505 {
 506         struct vm_area_struct *vma;
 507         struct task_struct *tsk = current;
 508         struct mm_struct *mm = tsk->mm;
 509         siginfo_t info;
 510
 511         info.si_code = SEGV_MAPERR;
 512
 513 #if 0
 514         printk("wf<pid=%d,wr=%d,addr=%08lx>\n",
 515                tsk->pid, write, address);
 516 #endif
 517         down_read(&mm->mmap_sem);
 518         vma = find_vma(mm, address);
 519         if(!vma)
 520                 goto bad_area;
 521         if(vma->vm_start <= address)
 522                 goto good_area;
 523         if(!(vma->vm_flags & VM_GROWSDOWN))
 524                 goto bad_area;
 525         if(expand_stack(vma, address))
 526                 goto bad_area;
 527 good_area:
 528         info.si_code = SEGV_ACCERR;
 529         if(write) {
 530                 if(!(vma->vm_flags & VM_WRITE))
 531                         goto bad_area;
 532         } else {
 533                 if(!(vma->vm_flags & (VM_READ | VM_EXEC)))
 534                         goto bad_area;
 535         }
 536         switch (handle_mm_fault(mm, vma, address, write)) {
 537         case VM_FAULT_SIGBUS:
 538         case VM_FAULT_OOM:
 539                 goto do_sigbus;
 540         }
 541         up_read(&mm->mmap_sem);
 542         return;
 543 bad_area:
 544         up_read(&mm->mmap_sem);
 545 #if 0
 546         printk("Window whee %s [%d]: segfaults at %08lx\n",
 547                tsk->comm, tsk->pid, address);
 548 #endif
 549         info.si_signo = SIGSEGV;
 550         info.si_errno = 0;
 551         /* info.si_code set above to make clear whether
 552            this was a SEGV_MAPERR or SEGV_ACCERR fault.  */
 553         info.si_addr = (void __user *) address;
 554         info.si_trapno = 0;
 555         force_sig_info (SIGSEGV, &info, tsk);
 556         return;
 557
 558 do_sigbus:
 559         up_read(&mm->mmap_sem);
 560         info.si_signo = SIGBUS;
 561         info.si_errno = 0;
 562         info.si_code = BUS_ADRERR;
 563         info.si_addr = (void __user *) address;
 564         info.si_trapno = 0;
 565         force_sig_info (SIGBUS, &info, tsk);
 566 }
 567
 568 void window_overflow_fault(void)
 569 {
 570         unsigned long sp;
 571
 572         sp = current_thread_info()->rwbuf_stkptrs[0];
 573         if(((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
 574                 force_user_fault(sp + 0x38, 1);
 575         force_user_fault(sp, 1);
 576 }
 577
 578 void window_underflow_fault(unsigned long sp)
 579 {
 580         if(((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
 581                 force_user_fault(sp + 0x38, 0);
 582         force_user_fault(sp, 0);
 583 }
 584
 585 void window_ret_fault(struct pt_regs *regs)
 586 {
 587         unsigned long sp;
 588
 589         sp = regs->u_regs[UREG_FP];
 590         if(((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
 591                 force_user_fault(sp + 0x38, 0);
 592         force_user_fault(sp, 0);
 593 }