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/memreg.h>
  28 #include <asm/openprom.h>
  29 #include <asm/oplib.h>
  30 #include <asm/smp.h>
  31 #include <asm/traps.h>
  32 #include <asm/uaccess.h>
  33
  34 extern int prom_node_root;
  35
  36 int show_unhandled_signals = 1;
  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 /* Return how much physical memory we have.  */
  52 unsigned long probe_memory(void)
  53 {
  54         unsigned long total = 0;
  55         int i;
  56
  57         for (i = 0; sp_banks[i].num_bytes; i++)
  58                 total += sp_banks[i].num_bytes;
  59
  60         return total;
  61 }
  62
  63 extern void sun4c_complete_all_stores(void);
  64
  65 /* Whee, a level 15 NMI interrupt memory error.  Let's have fun... */
  66 asmlinkage void sparc_lvl15_nmi(struct pt_regs *regs, unsigned long serr,
  67                                 unsigned long svaddr, unsigned long aerr,
  68                                 unsigned long avaddr)
  69 {
  70         sun4c_complete_all_stores();
  71         printk("FAULT: NMI received\n");
  72         printk("SREGS: Synchronous Error %08lx\n", serr);
  73         printk("       Synchronous Vaddr %08lx\n", svaddr);
  74         printk("      Asynchronous Error %08lx\n", aerr);
  75         printk("      Asynchronous Vaddr %08lx\n", avaddr);
  76         if (sun4c_memerr_reg)
  77                 printk("     Memory Parity Error %08lx\n", *sun4c_memerr_reg);
  78         printk("REGISTER DUMP:\n");
  79         show_regs(regs);
  80         prom_halt();
  81 }
  82
  83 static void unhandled_fault(unsigned long, struct task_struct *,
  84                 struct pt_regs *) __attribute__ ((noreturn));
  85
  86 static void unhandled_fault(unsigned long address, struct task_struct *tsk,
  87                      struct pt_regs *regs)
  88 {
  89         if((unsigned long) address < PAGE_SIZE) {
  90                 printk(KERN_ALERT
  91                     "Unable to handle kernel NULL pointer dereference\n");
  92         } else {
  93                 printk(KERN_ALERT "Unable to handle kernel paging request "
  94                        "at virtual address %08lx\n", address);
  95         }
  96         printk(KERN_ALERT "tsk->{mm,active_mm}->context = %08lx\n",
  97                 (tsk->mm ? tsk->mm->context : tsk->active_mm->context));
  98         printk(KERN_ALERT "tsk->{mm,active_mm}->pgd = %08lx\n",
  99                 (tsk->mm ? (unsigned long) tsk->mm->pgd :
 100                         (unsigned long) tsk->active_mm->pgd));
 101         die_if_kernel("Oops", regs);
 102 }
 103
 104 asmlinkage int lookup_fault(unsigned long pc, unsigned long ret_pc,
 105                             unsigned long address)
 106 {
 107         struct pt_regs regs;
 108         unsigned long g2;
 109         unsigned int insn;
 110         int i;
 111
 112         i = search_extables_range(ret_pc, &g2);
 113         switch (i) {
 114         case 3:
 115                 /* load & store will be handled by fixup */
 116                 return 3;
 117
 118         case 1:
 119                 /* store will be handled by fixup, load will bump out */
 120                 /* for _to_ macros */
 121                 insn = *((unsigned int *) pc);
 122                 if ((insn >> 21) & 1)
 123                         return 1;
 124                 break;
 125
 126         case 2:
 127                 /* load will be handled by fixup, store will bump out */
 128                 /* for _from_ macros */
 129                 insn = *((unsigned int *) pc);
 130                 if (!((insn >> 21) & 1) || ((insn>>19)&0x3f) == 15)
 131                         return 2;
 132                 break;
 133
 134         default:
 135                 break;
 136         }
 137
 138         memset(&regs, 0, sizeof (regs));
 139         regs.pc = pc;
 140         regs.npc = pc + 4;
 141         __asm__ __volatile__(
 142                 "rd %%psr, %0\n\t"
 143                 "nop\n\t"
 144                 "nop\n\t"
 145                 "nop\n" : "=r" (regs.psr));
 146         unhandled_fault(address, current, &regs);
 147
 148         /* Not reached */
 149         return 0;
 150 }
 151
 152 static inline void
 153 show_signal_msg(struct pt_regs *regs, int sig, int code,
 154                 unsigned long address, struct task_struct *tsk)
 155 {
 156         if (!unhandled_signal(tsk, sig))
 157                 return;
 158
 159         if (!printk_ratelimit())
 160                 return;
 161
 162         printk("%s%s[%d]: segfault at %lx ip %p (rpc %p) sp %p error %x",
 163                task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
 164                tsk->comm, task_pid_nr(tsk), address,
 165                (void *)regs->pc, (void *)regs->u_regs[UREG_I7],
 166                (void *)regs->u_regs[UREG_FP], code);
 167
 168         print_vma_addr(KERN_CONT " in ", regs->pc);
 169
 170         printk(KERN_CONT "\n");
 171 }
 172
 173 static void __do_fault_siginfo(int code, int sig, struct pt_regs *regs,
 174                                unsigned long addr)
 175 {
 176         siginfo_t info;
 177
 178         info.si_signo = sig;
 179         info.si_code = code;
 180         info.si_errno = 0;
 181         info.si_addr = (void __user *) addr;
 182         info.si_trapno = 0;
 183
 184         if (unlikely(show_unhandled_signals))
 185                 show_signal_msg(regs, sig, info.si_code,
 186                                 addr, current);
 187
 188         force_sig_info (sig, &info, current);
 189 }
 190
 191 extern unsigned long safe_compute_effective_address(struct pt_regs *,
 192                                                     unsigned int);
 193
 194 static unsigned long compute_si_addr(struct pt_regs *regs, int text_fault)
 195 {
 196         unsigned int insn;
 197
 198         if (text_fault)
 199                 return regs->pc;
 200
 201         if (regs->psr & PSR_PS) {
 202                 insn = *(unsigned int *) regs->pc;
 203         } else {
 204                 __get_user(insn, (unsigned int *) regs->pc);
 205         }
 206
 207         return safe_compute_effective_address(regs, insn);
 208 }
 209
 210 static noinline void do_fault_siginfo(int code, int sig, struct pt_regs *regs,
 211                                       int text_fault)
 212 {
 213         unsigned long addr = compute_si_addr(regs, text_fault);
 214
 215         __do_fault_siginfo(code, sig, regs, addr);
 216 }
 217
 218 asmlinkage void do_sparc_fault(struct pt_regs *regs, int text_fault, int write,
 219                                unsigned long address)
 220 {
 221         struct vm_area_struct *vma;
 222         struct task_struct *tsk = current;
 223         struct mm_struct *mm = tsk->mm;
 224         unsigned int fixup;
 225         unsigned long g2;
 226         int from_user = !(regs->psr & PSR_PS);
 227         int fault, code;
 228
 229         if(text_fault)
 230                 address = regs->pc;
 231
 232         /*
 233          * We fault-in kernel-space virtual memory on-demand. The
 234          * 'reference' page table is init_mm.pgd.
 235          *
 236          * NOTE! We MUST NOT take any locks for this case. We may
 237          * be in an interrupt or a critical region, and should
 238          * only copy the information from the master page table,
 239          * nothing more.
 240          */
 241         code = SEGV_MAPERR;
 242         if (!ARCH_SUN4C && address >= TASK_SIZE)
 243                 goto vmalloc_fault;
 244
 245         /*
 246          * If we're in an interrupt or have no user
 247          * context, we must not take the fault..
 248          */
 249         if (in_atomic() || !mm)
 250                 goto no_context;
 251
 252         perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
 253
 254         down_read(&mm->mmap_sem);
 255
 256         /*
 257          * The kernel referencing a bad kernel pointer can lock up
 258          * a sun4c machine completely, so we must attempt recovery.
 259          */
 260         if(!from_user && address >= PAGE_OFFSET)
 261                 goto bad_area;
 262
 263         vma = find_vma(mm, address);
 264         if(!vma)
 265                 goto bad_area;
 266         if(vma->vm_start <= address)
 267                 goto good_area;
 268         if(!(vma->vm_flags & VM_GROWSDOWN))
 269                 goto bad_area;
 270         if(expand_stack(vma, address))
 271                 goto bad_area;
 272         /*
 273          * Ok, we have a good vm_area for this memory access, so
 274          * we can handle it..
 275          */
 276 good_area:
 277         code = SEGV_ACCERR;
 278         if(write) {
 279                 if(!(vma->vm_flags & VM_WRITE))
 280                         goto bad_area;
 281         } else {
 282                 /* Allow reads even for write-only mappings */
 283                 if(!(vma->vm_flags & (VM_READ | VM_EXEC)))
 284                         goto bad_area;
 285         }
 286
 287         /*
 288          * If for any reason at all we couldn't handle the fault,
 289          * make sure we exit gracefully rather than endlessly redo
 290          * the fault.
 291          */
 292         fault = handle_mm_fault(mm, vma, address, write ? FAULT_FLAG_WRITE : 0);
 293         if (unlikely(fault & VM_FAULT_ERROR)) {
 294                 if (fault & VM_FAULT_OOM)
 295                         goto out_of_memory;
 296                 else if (fault & VM_FAULT_SIGBUS)
 297                         goto do_sigbus;
 298                 BUG();
 299         }
 300         if (fault & VM_FAULT_MAJOR) {
 301                 current->maj_flt++;
 302                 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs, address);
 303         } else {
 304                 current->min_flt++;
 305                 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs, address);
 306         }
 307         up_read(&mm->mmap_sem);
 308         return;
 309
 310         /*
 311          * Something tried to access memory that isn't in our memory map..
 312          * Fix it, but check if it's kernel or user first..
 313          */
 314 bad_area:
 315         up_read(&mm->mmap_sem);
 316
 317 bad_area_nosemaphore:
 318         /* User mode accesses just cause a SIGSEGV */
 319         if (from_user) {
 320                 do_fault_siginfo(code, SIGSEGV, regs, text_fault);
 321                 return;
 322         }
 323
 324         /* Is this in ex_table? */
 325 no_context:
 326         g2 = regs->u_regs[UREG_G2];
 327         if (!from_user) {
 328                 fixup = search_extables_range(regs->pc, &g2);
 329                 if (fixup > 10) { /* Values below are reserved for other things */
 330                         extern const unsigned __memset_start[];
 331                         extern const unsigned __memset_end[];
 332                         extern const unsigned __csum_partial_copy_start[];
 333                         extern const unsigned __csum_partial_copy_end[];
 334
 335 #ifdef DEBUG_EXCEPTIONS
 336                         printk("Exception: PC<%08lx> faddr<%08lx>\n", regs->pc, address);
 337                         printk("EX_TABLE: insn<%08lx> fixup<%08x> g2<%08lx>\n",
 338                                 regs->pc, fixup, g2);
 339 #endif
 340                         if ((regs->pc >= (unsigned long)__memset_start &&
 341                              regs->pc < (unsigned long)__memset_end) ||
 342                             (regs->pc >= (unsigned long)__csum_partial_copy_start &&
 343                              regs->pc < (unsigned long)__csum_partial_copy_end)) {
 344                                 regs->u_regs[UREG_I4] = address;
 345                                 regs->u_regs[UREG_I5] = regs->pc;
 346                         }
 347                         regs->u_regs[UREG_G2] = g2;
 348                         regs->pc = fixup;
 349                         regs->npc = regs->pc + 4;
 350                         return;
 351                 }
 352         }
 353
 354         unhandled_fault (address, tsk, regs);
 355         do_exit(SIGKILL);
 356
 357 /*
 358  * We ran out of memory, or some other thing happened to us that made
 359  * us unable to handle the page fault gracefully.
 360  */
 361 out_of_memory:
 362         up_read(&mm->mmap_sem);
 363         if (from_user) {
 364                 pagefault_out_of_memory();
 365                 return;
 366         }
 367         goto no_context;
 368
 369 do_sigbus:
 370         up_read(&mm->mmap_sem);
 371         do_fault_siginfo(BUS_ADRERR, SIGBUS, regs, text_fault);
 372         if (!from_user)
 373                 goto no_context;
 374
 375 vmalloc_fault:
 376         {
 377                 /*
 378                  * Synchronize this task's top level page-table
 379                  * with the 'reference' page table.
 380                  */
 381                 int offset = pgd_index(address);
 382                 pgd_t *pgd, *pgd_k;
 383                 pmd_t *pmd, *pmd_k;
 384
 385                 pgd = tsk->active_mm->pgd + offset;
 386                 pgd_k = init_mm.pgd + offset;
 387
 388                 if (!pgd_present(*pgd)) {
 389                         if (!pgd_present(*pgd_k))
 390                                 goto bad_area_nosemaphore;
 391                         pgd_val(*pgd) = pgd_val(*pgd_k);
 392                         return;
 393                 }
 394
 395                 pmd = pmd_offset(pgd, address);
 396                 pmd_k = pmd_offset(pgd_k, address);
 397
 398                 if (pmd_present(*pmd) || !pmd_present(*pmd_k))
 399                         goto bad_area_nosemaphore;
 400                 *pmd = *pmd_k;
 401                 return;
 402         }
 403 }
 404
 405 asmlinkage void do_sun4c_fault(struct pt_regs *regs, int text_fault, int write,
 406                                unsigned long address)
 407 {
 408         extern void sun4c_update_mmu_cache(struct vm_area_struct *,
 409                                            unsigned long,pte_t *);
 410         extern pte_t *sun4c_pte_offset_kernel(pmd_t *,unsigned long);
 411         struct task_struct *tsk = current;
 412         struct mm_struct *mm = tsk->mm;
 413         pgd_t *pgdp;
 414         pte_t *ptep;
 415
 416         if (text_fault) {
 417                 address = regs->pc;
 418         } else if (!write &&
 419                    !(regs->psr & PSR_PS)) {
 420                 unsigned int insn, __user *ip;
 421
 422                 ip = (unsigned int __user *)regs->pc;
 423                 if (!get_user(insn, ip)) {
 424                         if ((insn & 0xc1680000) == 0xc0680000)
 425                                 write = 1;
 426                 }
 427         }
 428
 429         if (!mm) {
 430                 /* We are oopsing. */
 431                 do_sparc_fault(regs, text_fault, write, address);
 432                 BUG();  /* P3 Oops already, you bitch */
 433         }
 434
 435         pgdp = pgd_offset(mm, address);
 436         ptep = sun4c_pte_offset_kernel((pmd_t *) pgdp, address);
 437
 438         if (pgd_val(*pgdp)) {
 439             if (write) {
 440                 if ((pte_val(*ptep) & (_SUN4C_PAGE_WRITE|_SUN4C_PAGE_PRESENT))
 441                                    == (_SUN4C_PAGE_WRITE|_SUN4C_PAGE_PRESENT)) {
 442                         unsigned long flags;
 443
 444                         *ptep = __pte(pte_val(*ptep) | _SUN4C_PAGE_ACCESSED |
 445                                       _SUN4C_PAGE_MODIFIED |
 446                                       _SUN4C_PAGE_VALID |
 447                                       _SUN4C_PAGE_DIRTY);
 448
 449                         local_irq_save(flags);
 450                         if (sun4c_get_segmap(address) != invalid_segment) {
 451                                 sun4c_put_pte(address, pte_val(*ptep));
 452                                 local_irq_restore(flags);
 453                                 return;
 454                         }
 455                         local_irq_restore(flags);
 456                 }
 457             } else {
 458                 if ((pte_val(*ptep) & (_SUN4C_PAGE_READ|_SUN4C_PAGE_PRESENT))
 459                                    == (_SUN4C_PAGE_READ|_SUN4C_PAGE_PRESENT)) {
 460                         unsigned long flags;
 461
 462                         *ptep = __pte(pte_val(*ptep) | _SUN4C_PAGE_ACCESSED |
 463                                       _SUN4C_PAGE_VALID);
 464
 465                         local_irq_save(flags);
 466                         if (sun4c_get_segmap(address) != invalid_segment) {
 467                                 sun4c_put_pte(address, pte_val(*ptep));
 468                                 local_irq_restore(flags);
 469                                 return;
 470                         }
 471                         local_irq_restore(flags);
 472                 }
 473             }
 474         }
 475
 476         /* This conditional is 'interesting'. */
 477         if (pgd_val(*pgdp) && !(write && !(pte_val(*ptep) & _SUN4C_PAGE_WRITE))
 478             && (pte_val(*ptep) & _SUN4C_PAGE_VALID))
 479                 /* Note: It is safe to not grab the MMAP semaphore here because
 480                  *       we know that update_mmu_cache() will not sleep for
 481                  *       any reason (at least not in the current implementation)
 482                  *       and therefore there is no danger of another thread getting
 483                  *       on the CPU and doing a shrink_mmap() on this vma.
 484                  */
 485                 sun4c_update_mmu_cache (find_vma(current->mm, address), address,
 486                                         ptep);
 487         else
 488                 do_sparc_fault(regs, text_fault, write, address);
 489 }
 490
 491 /* This always deals with user addresses. */
 492 static void force_user_fault(unsigned long address, int write)
 493 {
 494         struct vm_area_struct *vma;
 495         struct task_struct *tsk = current;
 496         struct mm_struct *mm = tsk->mm;
 497         int code;
 498
 499         code = SEGV_MAPERR;
 500
 501         down_read(&mm->mmap_sem);
 502         vma = find_vma(mm, address);
 503         if(!vma)
 504                 goto bad_area;
 505         if(vma->vm_start <= address)
 506                 goto good_area;
 507         if(!(vma->vm_flags & VM_GROWSDOWN))
 508                 goto bad_area;
 509         if(expand_stack(vma, address))
 510                 goto bad_area;
 511 good_area:
 512         code = SEGV_ACCERR;
 513         if(write) {
 514                 if(!(vma->vm_flags & VM_WRITE))
 515                         goto bad_area;
 516         } else {
 517                 if(!(vma->vm_flags & (VM_READ | VM_EXEC)))
 518                         goto bad_area;
 519         }
 520         switch (handle_mm_fault(mm, vma, address, write ? FAULT_FLAG_WRITE : 0)) {
 521         case VM_FAULT_SIGBUS:
 522         case VM_FAULT_OOM:
 523                 goto do_sigbus;
 524         }
 525         up_read(&mm->mmap_sem);
 526         return;
 527 bad_area:
 528         up_read(&mm->mmap_sem);
 529         __do_fault_siginfo(code, SIGSEGV, tsk->thread.kregs, address);
 530         return;
 531
 532 do_sigbus:
 533         up_read(&mm->mmap_sem);
 534         __do_fault_siginfo(BUS_ADRERR, SIGBUS, tsk->thread.kregs, address);
 535 }
 536
 537 static void check_stack_aligned(unsigned long sp)
 538 {
 539         if (sp & 0x7UL)
 540                 force_sig(SIGILL, current);
 541 }
 542
 543 void window_overflow_fault(void)
 544 {
 545         unsigned long sp;
 546
 547         sp = current_thread_info()->rwbuf_stkptrs[0];
 548         if(((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
 549                 force_user_fault(sp + 0x38, 1);
 550         force_user_fault(sp, 1);
 551
 552         check_stack_aligned(sp);
 553 }
 554
 555 void window_underflow_fault(unsigned long sp)
 556 {
 557         if(((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
 558                 force_user_fault(sp + 0x38, 0);
 559         force_user_fault(sp, 0);
 560
 561         check_stack_aligned(sp);
 562 }
 563
 564 void window_ret_fault(struct pt_regs *regs)
 565 {
 566         unsigned long sp;
 567
 568         sp = regs->u_regs[UREG_FP];
 569         if(((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
 570                 force_user_fault(sp + 0x38, 0);
 571         force_user_fault(sp, 0);
 572
 573         check_stack_aligned(sp);
 574 }