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/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 int show_unhandled_signals = 1;
  39
  40 /* At boot time we determine these two values necessary for setting
  41  * up the segment maps and page table entries (pte's).
  42  */
  43
  44 int num_segmaps, num_contexts;
  45 int invalid_segment;
  46
  47 /* various Virtual Address Cache parameters we find at boot time... */
  48
  49 int vac_size, vac_linesize, vac_do_hw_vac_flushes;
  50 int vac_entries_per_context, vac_entries_per_segment;
  51 int vac_entries_per_page;
  52
  53 /* Return how much physical memory we have.  */
  54 unsigned long probe_memory(void)
  55 {
  56         unsigned long total = 0;
  57         int i;
  58
  59         for (i = 0; sp_banks[i].num_bytes; i++)
  60                 total += sp_banks[i].num_bytes;
  61
  62         return total;
  63 }
  64
  65 extern void sun4c_complete_all_stores(void);
  66
  67 /* Whee, a level 15 NMI interrupt memory error.  Let's have fun... */
  68 asmlinkage void sparc_lvl15_nmi(struct pt_regs *regs, unsigned long serr,
  69                                 unsigned long svaddr, unsigned long aerr,
  70                                 unsigned long avaddr)
  71 {
  72         sun4c_complete_all_stores();
  73         printk("FAULT: NMI received\n");
  74         printk("SREGS: Synchronous Error %08lx\n", serr);
  75         printk("       Synchronous Vaddr %08lx\n", svaddr);
  76         printk("      Asynchronous Error %08lx\n", aerr);
  77         printk("      Asynchronous Vaddr %08lx\n", avaddr);
  78         if (sun4c_memerr_reg)
  79                 printk("     Memory Parity Error %08lx\n", *sun4c_memerr_reg);
  80         printk("REGISTER DUMP:\n");
  81         show_regs(regs);
  82         prom_halt();
  83 }
  84
  85 static void unhandled_fault(unsigned long, struct task_struct *,
  86                 struct pt_regs *) __attribute__ ((noreturn));
  87
  88 static void unhandled_fault(unsigned long address, struct task_struct *tsk,
  89                      struct pt_regs *regs)
  90 {
  91         if((unsigned long) address < PAGE_SIZE) {
  92                 printk(KERN_ALERT
  93                     "Unable to handle kernel NULL pointer dereference\n");
  94         } else {
  95                 printk(KERN_ALERT "Unable to handle kernel paging request "
  96                        "at virtual address %08lx\n", address);
  97         }
  98         printk(KERN_ALERT "tsk->{mm,active_mm}->context = %08lx\n",
  99                 (tsk->mm ? tsk->mm->context : tsk->active_mm->context));
 100         printk(KERN_ALERT "tsk->{mm,active_mm}->pgd = %08lx\n",
 101                 (tsk->mm ? (unsigned long) tsk->mm->pgd :
 102                         (unsigned long) tsk->active_mm->pgd));
 103         die_if_kernel("Oops", regs);
 104 }
 105
 106 asmlinkage int lookup_fault(unsigned long pc, unsigned long ret_pc,
 107                             unsigned long address)
 108 {
 109         struct pt_regs regs;
 110         unsigned long g2;
 111         unsigned int insn;
 112         int i;
 113
 114         i = search_extables_range(ret_pc, &g2);
 115         switch (i) {
 116         case 3:
 117                 /* load & store will be handled by fixup */
 118                 return 3;
 119
 120         case 1:
 121                 /* store will be handled by fixup, load will bump out */
 122                 /* for _to_ macros */
 123                 insn = *((unsigned int *) pc);
 124                 if ((insn >> 21) & 1)
 125                         return 1;
 126                 break;
 127
 128         case 2:
 129                 /* load will be handled by fixup, store will bump out */
 130                 /* for _from_ macros */
 131                 insn = *((unsigned int *) pc);
 132                 if (!((insn >> 21) & 1) || ((insn>>19)&0x3f) == 15)
 133                         return 2;
 134                 break;
 135
 136         default:
 137                 break;
 138         }
 139
 140         memset(&regs, 0, sizeof (regs));
 141         regs.pc = pc;
 142         regs.npc = pc + 4;
 143         __asm__ __volatile__(
 144                 "rd %%psr, %0\n\t"
 145                 "nop\n\t"
 146                 "nop\n\t"
 147                 "nop\n" : "=r" (regs.psr));
 148         unhandled_fault(address, current, &regs);
 149
 150         /* Not reached */
 151         return 0;
 152 }
 153
 154 static inline void
 155 show_signal_msg(struct pt_regs *regs, int sig, int code,
 156                 unsigned long address, struct task_struct *tsk)
 157 {
 158         if (!unhandled_signal(tsk, sig))
 159                 return;
 160
 161         if (!printk_ratelimit())
 162                 return;
 163
 164         printk("%s%s[%d]: segfault at %lx ip %p (rpc %p) sp %p error %x",
 165                task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
 166                tsk->comm, task_pid_nr(tsk), address,
 167                (void *)regs->pc, (void *)regs->u_regs[UREG_I7],
 168                (void *)regs->u_regs[UREG_FP], code);
 169
 170         print_vma_addr(KERN_CONT " in ", regs->pc);
 171
 172         printk(KERN_CONT "\n");
 173 }
 174
 175 static void __do_fault_siginfo(int code, int sig, struct pt_regs *regs,
 176                                unsigned long addr)
 177 {
 178         siginfo_t info;
 179
 180         info.si_signo = sig;
 181         info.si_code = code;
 182         info.si_errno = 0;
 183         info.si_addr = (void __user *) addr;
 184         info.si_trapno = 0;
 185
 186         if (unlikely(show_unhandled_signals))
 187                 show_signal_msg(regs, sig, info.si_code,
 188                                 addr, current);
 189
 190         force_sig_info (sig, &info, current);
 191 }
 192
 193 extern unsigned long safe_compute_effective_address(struct pt_regs *,
 194                                                     unsigned int);
 195
 196 static unsigned long compute_si_addr(struct pt_regs *regs, int text_fault)
 197 {
 198         unsigned int insn;
 199
 200         if (text_fault)
 201                 return regs->pc;
 202
 203         if (regs->psr & PSR_PS) {
 204                 insn = *(unsigned int *) regs->pc;
 205         } else {
 206                 __get_user(insn, (unsigned int *) regs->pc);
 207         }
 208
 209         return safe_compute_effective_address(regs, insn);
 210 }
 211
 212 static noinline void do_fault_siginfo(int code, int sig, struct pt_regs *regs,
 213                                       int text_fault)
 214 {
 215         unsigned long addr = compute_si_addr(regs, text_fault);
 216
 217         __do_fault_siginfo(code, sig, regs, addr);
 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         int from_user = !(regs->psr & PSR_PS);
 229         int fault, code;
 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         code = SEGV_MAPERR;
 244         if (!ARCH_SUN4C && address >= TASK_SIZE)
 245                 goto vmalloc_fault;
 246
 247         /*
 248          * If we're in an interrupt or have no user
 249          * context, we must not take the fault..
 250          */
 251         if (in_atomic() || !mm)
 252                 goto no_context;
 253
 254         perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
 255
 256         down_read(&mm->mmap_sem);
 257
 258         /*
 259          * The kernel referencing a bad kernel pointer can lock up
 260          * a sun4c machine completely, so we must attempt recovery.
 261          */
 262         if(!from_user && address >= PAGE_OFFSET)
 263                 goto bad_area;
 264
 265         vma = find_vma(mm, address);
 266         if(!vma)
 267                 goto bad_area;
 268         if(vma->vm_start <= address)
 269                 goto good_area;
 270         if(!(vma->vm_flags & VM_GROWSDOWN))
 271                 goto bad_area;
 272         if(expand_stack(vma, address))
 273                 goto bad_area;
 274         /*
 275          * Ok, we have a good vm_area for this memory access, so
 276          * we can handle it..
 277          */
 278 good_area:
 279         code = SEGV_ACCERR;
 280         if(write) {
 281                 if(!(vma->vm_flags & VM_WRITE))
 282                         goto bad_area;
 283         } else {
 284                 /* Allow reads even for write-only mappings */
 285                 if(!(vma->vm_flags & (VM_READ | VM_EXEC)))
 286                         goto bad_area;
 287         }
 288
 289         /*
 290          * If for any reason at all we couldn't handle the fault,
 291          * make sure we exit gracefully rather than endlessly redo
 292          * the fault.
 293          */
 294         fault = handle_mm_fault(mm, vma, address, write ? FAULT_FLAG_WRITE : 0);
 295         if (unlikely(fault & VM_FAULT_ERROR)) {
 296                 if (fault & VM_FAULT_OOM)
 297                         goto out_of_memory;
 298                 else if (fault & VM_FAULT_SIGBUS)
 299                         goto do_sigbus;
 300                 BUG();
 301         }
 302         if (fault & VM_FAULT_MAJOR) {
 303                 current->maj_flt++;
 304                 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs, address);
 305         } else {
 306                 current->min_flt++;
 307                 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs, address);
 308         }
 309         up_read(&mm->mmap_sem);
 310         return;
 311
 312         /*
 313          * Something tried to access memory that isn't in our memory map..
 314          * Fix it, but check if it's kernel or user first..
 315          */
 316 bad_area:
 317         up_read(&mm->mmap_sem);
 318
 319 bad_area_nosemaphore:
 320         /* User mode accesses just cause a SIGSEGV */
 321         if (from_user) {
 322                 do_fault_siginfo(code, SIGSEGV, regs, text_fault);
 323                 return;
 324         }
 325
 326         /* Is this in ex_table? */
 327 no_context:
 328         g2 = regs->u_regs[UREG_G2];
 329         if (!from_user) {
 330                 fixup = search_extables_range(regs->pc, &g2);
 331                 if (fixup > 10) { /* Values below are reserved for other things */
 332                         extern const unsigned __memset_start[];
 333                         extern const unsigned __memset_end[];
 334                         extern const unsigned __csum_partial_copy_start[];
 335                         extern const unsigned __csum_partial_copy_end[];
 336
 337 #ifdef DEBUG_EXCEPTIONS
 338                         printk("Exception: PC<%08lx> faddr<%08lx>\n", regs->pc, address);
 339                         printk("EX_TABLE: insn<%08lx> fixup<%08x> g2<%08lx>\n",
 340                                 regs->pc, fixup, g2);
 341 #endif
 342                         if ((regs->pc >= (unsigned long)__memset_start &&
 343                              regs->pc < (unsigned long)__memset_end) ||
 344                             (regs->pc >= (unsigned long)__csum_partial_copy_start &&
 345                              regs->pc < (unsigned long)__csum_partial_copy_end)) {
 346                                 regs->u_regs[UREG_I4] = address;
 347                                 regs->u_regs[UREG_I5] = regs->pc;
 348                         }
 349                         regs->u_regs[UREG_G2] = g2;
 350                         regs->pc = fixup;
 351                         regs->npc = regs->pc + 4;
 352                         return;
 353                 }
 354         }
 355
 356         unhandled_fault (address, tsk, regs);
 357         do_exit(SIGKILL);
 358
 359 /*
 360  * We ran out of memory, or some other thing happened to us that made
 361  * us unable to handle the page fault gracefully.
 362  */
 363 out_of_memory:
 364         up_read(&mm->mmap_sem);
 365         if (from_user) {
 366                 pagefault_out_of_memory();
 367                 return;
 368         }
 369         goto no_context;
 370
 371 do_sigbus:
 372         up_read(&mm->mmap_sem);
 373         do_fault_siginfo(BUS_ADRERR, SIGBUS, regs, text_fault);
 374         if (!from_user)
 375                 goto no_context;
 376
 377 vmalloc_fault:
 378         {
 379                 /*
 380                  * Synchronize this task's top level page-table
 381                  * with the 'reference' page table.
 382                  */
 383                 int offset = pgd_index(address);
 384                 pgd_t *pgd, *pgd_k;
 385                 pmd_t *pmd, *pmd_k;
 386
 387                 pgd = tsk->active_mm->pgd + offset;
 388                 pgd_k = init_mm.pgd + offset;
 389
 390                 if (!pgd_present(*pgd)) {
 391                         if (!pgd_present(*pgd_k))
 392                                 goto bad_area_nosemaphore;
 393                         pgd_val(*pgd) = pgd_val(*pgd_k);
 394                         return;
 395                 }
 396
 397                 pmd = pmd_offset(pgd, address);
 398                 pmd_k = pmd_offset(pgd_k, address);
 399
 400                 if (pmd_present(*pmd) || !pmd_present(*pmd_k))
 401                         goto bad_area_nosemaphore;
 402                 *pmd = *pmd_k;
 403                 return;
 404         }
 405 }
 406
 407 asmlinkage void do_sun4c_fault(struct pt_regs *regs, int text_fault, int write,
 408                                unsigned long address)
 409 {
 410         extern void sun4c_update_mmu_cache(struct vm_area_struct *,
 411                                            unsigned long,pte_t *);
 412         extern pte_t *sun4c_pte_offset_kernel(pmd_t *,unsigned long);
 413         struct task_struct *tsk = current;
 414         struct mm_struct *mm = tsk->mm;
 415         pgd_t *pgdp;
 416         pte_t *ptep;
 417
 418         if (text_fault) {
 419                 address = regs->pc;
 420         } else if (!write &&
 421                    !(regs->psr & PSR_PS)) {
 422                 unsigned int insn, __user *ip;
 423
 424                 ip = (unsigned int __user *)regs->pc;
 425                 if (!get_user(insn, ip)) {
 426                         if ((insn & 0xc1680000) == 0xc0680000)
 427                                 write = 1;
 428                 }
 429         }
 430
 431         if (!mm) {
 432                 /* We are oopsing. */
 433                 do_sparc_fault(regs, text_fault, write, address);
 434                 BUG();  /* P3 Oops already, you bitch */
 435         }
 436
 437         pgdp = pgd_offset(mm, address);
 438         ptep = sun4c_pte_offset_kernel((pmd_t *) pgdp, address);
 439
 440         if (pgd_val(*pgdp)) {
 441             if (write) {
 442                 if ((pte_val(*ptep) & (_SUN4C_PAGE_WRITE|_SUN4C_PAGE_PRESENT))
 443                                    == (_SUN4C_PAGE_WRITE|_SUN4C_PAGE_PRESENT)) {
 444                         unsigned long flags;
 445
 446                         *ptep = __pte(pte_val(*ptep) | _SUN4C_PAGE_ACCESSED |
 447                                       _SUN4C_PAGE_MODIFIED |
 448                                       _SUN4C_PAGE_VALID |
 449                                       _SUN4C_PAGE_DIRTY);
 450
 451                         local_irq_save(flags);
 452                         if (sun4c_get_segmap(address) != invalid_segment) {
 453                                 sun4c_put_pte(address, pte_val(*ptep));
 454                                 local_irq_restore(flags);
 455                                 return;
 456                         }
 457                         local_irq_restore(flags);
 458                 }
 459             } else {
 460                 if ((pte_val(*ptep) & (_SUN4C_PAGE_READ|_SUN4C_PAGE_PRESENT))
 461                                    == (_SUN4C_PAGE_READ|_SUN4C_PAGE_PRESENT)) {
 462                         unsigned long flags;
 463
 464                         *ptep = __pte(pte_val(*ptep) | _SUN4C_PAGE_ACCESSED |
 465                                       _SUN4C_PAGE_VALID);
 466
 467                         local_irq_save(flags);
 468                         if (sun4c_get_segmap(address) != invalid_segment) {
 469                                 sun4c_put_pte(address, pte_val(*ptep));
 470                                 local_irq_restore(flags);
 471                                 return;
 472                         }
 473                         local_irq_restore(flags);
 474                 }
 475             }
 476         }
 477
 478         /* This conditional is 'interesting'. */
 479         if (pgd_val(*pgdp) && !(write && !(pte_val(*ptep) & _SUN4C_PAGE_WRITE))
 480             && (pte_val(*ptep) & _SUN4C_PAGE_VALID))
 481                 /* Note: It is safe to not grab the MMAP semaphore here because
 482                  *       we know that update_mmu_cache() will not sleep for
 483                  *       any reason (at least not in the current implementation)
 484                  *       and therefore there is no danger of another thread getting
 485                  *       on the CPU and doing a shrink_mmap() on this vma.
 486                  */
 487                 sun4c_update_mmu_cache (find_vma(current->mm, address), address,
 488                                         ptep);
 489         else
 490                 do_sparc_fault(regs, text_fault, write, address);
 491 }
 492
 493 /* This always deals with user addresses. */
 494 static void force_user_fault(unsigned long address, int write)
 495 {
 496         struct vm_area_struct *vma;
 497         struct task_struct *tsk = current;
 498         struct mm_struct *mm = tsk->mm;
 499         int code;
 500
 501         code = SEGV_MAPERR;
 502
 503         down_read(&mm->mmap_sem);
 504         vma = find_vma(mm, address);
 505         if(!vma)
 506                 goto bad_area;
 507         if(vma->vm_start <= address)
 508                 goto good_area;
 509         if(!(vma->vm_flags & VM_GROWSDOWN))
 510                 goto bad_area;
 511         if(expand_stack(vma, address))
 512                 goto bad_area;
 513 good_area:
 514         code = SEGV_ACCERR;
 515         if(write) {
 516                 if(!(vma->vm_flags & VM_WRITE))
 517                         goto bad_area;
 518         } else {
 519                 if(!(vma->vm_flags & (VM_READ | VM_EXEC)))
 520                         goto bad_area;
 521         }
 522         switch (handle_mm_fault(mm, vma, address, write ? FAULT_FLAG_WRITE : 0)) {
 523         case VM_FAULT_SIGBUS:
 524         case VM_FAULT_OOM:
 525                 goto do_sigbus;
 526         }
 527         up_read(&mm->mmap_sem);
 528         return;
 529 bad_area:
 530         up_read(&mm->mmap_sem);
 531         __do_fault_siginfo(code, SIGSEGV, tsk->thread.kregs, address);
 532         return;
 533
 534 do_sigbus:
 535         up_read(&mm->mmap_sem);
 536         __do_fault_siginfo(BUS_ADRERR, SIGBUS, tsk->thread.kregs, address);
 537 }
 538
 539 static void check_stack_aligned(unsigned long sp)
 540 {
 541         if (sp & 0x7UL)
 542                 force_sig(SIGILL, current);
 543 }
 544
 545 void window_overflow_fault(void)
 546 {
 547         unsigned long sp;
 548
 549         sp = current_thread_info()->rwbuf_stkptrs[0];
 550         if(((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
 551                 force_user_fault(sp + 0x38, 1);
 552         force_user_fault(sp, 1);
 553
 554         check_stack_aligned(sp);
 555 }
 556
 557 void window_underflow_fault(unsigned long sp)
 558 {
 559         if(((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
 560                 force_user_fault(sp + 0x38, 0);
 561         force_user_fault(sp, 0);
 562
 563         check_stack_aligned(sp);
 564 }
 565
 566 void window_ret_fault(struct pt_regs *regs)
 567 {
 568         unsigned long sp;
 569
 570         sp = regs->u_regs[UREG_FP];
 571         if(((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
 572                 force_user_fault(sp + 0x38, 0);
 573         force_user_fault(sp, 0);
 574
 575         check_stack_aligned(sp);
 576 }