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/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 int show_unhandled_signals = 1;
  38
  39 /* At boot time we determine these two values necessary for setting
  40  * up the segment maps and page table entries (pte's).
  41  */
  42
  43 int num_segmaps, num_contexts;
  44 int invalid_segment;
  45
  46 /* various Virtual Address Cache parameters we find at boot time... */
  47
  48 int vac_size, vac_linesize, vac_do_hw_vac_flushes;
  49 int vac_entries_per_context, vac_entries_per_segment;
  50 int vac_entries_per_page;
  51
  52 /* Return how much physical memory we have.  */
  53 unsigned long probe_memory(void)
  54 {
  55         unsigned long total = 0;
  56         int i;
  57
  58         for (i = 0; sp_banks[i].num_bytes; i++)
  59                 total += sp_banks[i].num_bytes;
  60
  61         return total;
  62 }
  63
  64 extern void sun4c_complete_all_stores(void);
  65
  66 /* Whee, a level 15 NMI interrupt memory error.  Let's have fun... */
  67 asmlinkage void sparc_lvl15_nmi(struct pt_regs *regs, unsigned long serr,
  68                                 unsigned long svaddr, unsigned long aerr,
  69                                 unsigned long avaddr)
  70 {
  71         sun4c_complete_all_stores();
  72         printk("FAULT: NMI received\n");
  73         printk("SREGS: Synchronous Error %08lx\n", serr);
  74         printk("       Synchronous Vaddr %08lx\n", svaddr);
  75         printk("      Asynchronous Error %08lx\n", aerr);
  76         printk("      Asynchronous Vaddr %08lx\n", avaddr);
  77         if (sun4c_memerr_reg)
  78                 printk("     Memory Parity Error %08lx\n", *sun4c_memerr_reg);
  79         printk("REGISTER DUMP:\n");
  80         show_regs(regs);
  81         prom_halt();
  82 }
  83
  84 static void unhandled_fault(unsigned long, struct task_struct *,
  85                 struct pt_regs *) __attribute__ ((noreturn));
  86
  87 static void unhandled_fault(unsigned long address, struct task_struct *tsk,
  88                      struct pt_regs *regs)
  89 {
  90         if((unsigned long) address < PAGE_SIZE) {
  91                 printk(KERN_ALERT
  92                     "Unable to handle kernel NULL pointer dereference\n");
  93         } else {
  94                 printk(KERN_ALERT "Unable to handle kernel paging request "
  95                        "at virtual address %08lx\n", address);
  96         }
  97         printk(KERN_ALERT "tsk->{mm,active_mm}->context = %08lx\n",
  98                 (tsk->mm ? tsk->mm->context : tsk->active_mm->context));
  99         printk(KERN_ALERT "tsk->{mm,active_mm}->pgd = %08lx\n",
 100                 (tsk->mm ? (unsigned long) tsk->mm->pgd :
 101                         (unsigned long) tsk->active_mm->pgd));
 102         die_if_kernel("Oops", regs);
 103 }
 104
 105 asmlinkage int lookup_fault(unsigned long pc, unsigned long ret_pc,
 106                             unsigned long address)
 107 {
 108         struct pt_regs regs;
 109         unsigned long g2;
 110         unsigned int insn;
 111         int i;
 112
 113         i = search_extables_range(ret_pc, &g2);
 114         switch (i) {
 115         case 3:
 116                 /* load & store will be handled by fixup */
 117                 return 3;
 118
 119         case 1:
 120                 /* store will be handled by fixup, load will bump out */
 121                 /* for _to_ macros */
 122                 insn = *((unsigned int *) pc);
 123                 if ((insn >> 21) & 1)
 124                         return 1;
 125                 break;
 126
 127         case 2:
 128                 /* load will be handled by fixup, store will bump out */
 129                 /* for _from_ macros */
 130                 insn = *((unsigned int *) pc);
 131                 if (!((insn >> 21) & 1) || ((insn>>19)&0x3f) == 15)
 132                         return 2;
 133                 break;
 134
 135         default:
 136                 break;
 137         }
 138
 139         memset(&regs, 0, sizeof (regs));
 140         regs.pc = pc;
 141         regs.npc = pc + 4;
 142         __asm__ __volatile__(
 143                 "rd %%psr, %0\n\t"
 144                 "nop\n\t"
 145                 "nop\n\t"
 146                 "nop\n" : "=r" (regs.psr));
 147         unhandled_fault(address, current, &regs);
 148
 149         /* Not reached */
 150         return 0;
 151 }
 152
 153 static inline void
 154 show_signal_msg(struct pt_regs *regs, int sig, int code,
 155                 unsigned long address, struct task_struct *tsk)
 156 {
 157         if (!unhandled_signal(tsk, sig))
 158                 return;
 159
 160         if (!printk_ratelimit())
 161                 return;
 162
 163         printk("%s%s[%d]: segfault at %lx ip %p (rpc %p) sp %p error %x",
 164                task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
 165                tsk->comm, task_pid_nr(tsk), address,
 166                (void *)regs->pc, (void *)regs->u_regs[UREG_I7],
 167                (void *)regs->u_regs[UREG_FP], code);
 168
 169         print_vma_addr(KERN_CONT " in ", regs->pc);
 170
 171         printk(KERN_CONT "\n");
 172 }
 173
 174 static void __do_fault_siginfo(int code, int sig, struct pt_regs *regs,
 175                                unsigned long addr)
 176 {
 177         siginfo_t info;
 178
 179         info.si_signo = sig;
 180         info.si_code = code;
 181         info.si_errno = 0;
 182         info.si_addr = (void __user *) addr;
 183         info.si_trapno = 0;
 184
 185         if (unlikely(show_unhandled_signals))
 186                 show_signal_msg(regs, sig, info.si_code,
 187                                 addr, current);
 188
 189         force_sig_info (sig, &info, current);
 190 }
 191
 192 extern unsigned long safe_compute_effective_address(struct pt_regs *,
 193                                                     unsigned int);
 194
 195 static unsigned long compute_si_addr(struct pt_regs *regs, int text_fault)
 196 {
 197         unsigned int insn;
 198
 199         if (text_fault)
 200                 return regs->pc;
 201
 202         if (regs->psr & PSR_PS) {
 203                 insn = *(unsigned int *) regs->pc;
 204         } else {
 205                 __get_user(insn, (unsigned int *) regs->pc);
 206         }
 207
 208         return safe_compute_effective_address(regs, insn);
 209 }
 210
 211 static noinline void do_fault_siginfo(int code, int sig, struct pt_regs *regs,
 212                                       int text_fault)
 213 {
 214         unsigned long addr = compute_si_addr(regs, text_fault);
 215
 216         __do_fault_siginfo(code, sig, regs, addr);
 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         int from_user = !(regs->psr & PSR_PS);
 228         int fault, code;
 229
 230         if(text_fault)
 231                 address = regs->pc;
 232
 233         /*
 234          * We fault-in kernel-space virtual memory on-demand. The
 235          * 'reference' page table is init_mm.pgd.
 236          *
 237          * NOTE! We MUST NOT take any locks for this case. We may
 238          * be in an interrupt or a critical region, and should
 239          * only copy the information from the master page table,
 240          * nothing more.
 241          */
 242         code = SEGV_MAPERR;
 243         if (!ARCH_SUN4C && address >= TASK_SIZE)
 244                 goto vmalloc_fault;
 245
 246         /*
 247          * If we're in an interrupt or have no user
 248          * context, we must not take the fault..
 249          */
 250         if (in_atomic() || !mm)
 251                 goto no_context;
 252
 253         perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
 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         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 ? FAULT_FLAG_WRITE : 0);
 294         if (unlikely(fault & VM_FAULT_ERROR)) {
 295                 if (fault & VM_FAULT_OOM)
 296                         goto out_of_memory;
 297                 else if (fault & VM_FAULT_SIGSEGV)
 298                         goto bad_area;
 299                 else if (fault & VM_FAULT_SIGBUS)
 300                         goto do_sigbus;
 301                 BUG();
 302         }
 303         if (fault & VM_FAULT_MAJOR) {
 304                 current->maj_flt++;
 305                 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs, address);
 306         } else {
 307                 current->min_flt++;
 308                 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs, address);
 309         }
 310         up_read(&mm->mmap_sem);
 311         return;
 312
 313         /*
 314          * Something tried to access memory that isn't in our memory map..
 315          * Fix it, but check if it's kernel or user first..
 316          */
 317 bad_area:
 318         up_read(&mm->mmap_sem);
 319
 320 bad_area_nosemaphore:
 321         /* User mode accesses just cause a SIGSEGV */
 322         if (from_user) {
 323                 do_fault_siginfo(code, SIGSEGV, regs, text_fault);
 324                 return;
 325         }
 326
 327         /* Is this in ex_table? */
 328 no_context:
 329         g2 = regs->u_regs[UREG_G2];
 330         if (!from_user) {
 331                 fixup = search_extables_range(regs->pc, &g2);
 332                 if (fixup > 10) { /* Values below are reserved for other things */
 333                         extern const unsigned __memset_start[];
 334                         extern const unsigned __memset_end[];
 335                         extern const unsigned __csum_partial_copy_start[];
 336                         extern const unsigned __csum_partial_copy_end[];
 337
 338 #ifdef DEBUG_EXCEPTIONS
 339                         printk("Exception: PC<%08lx> faddr<%08lx>\n", regs->pc, address);
 340                         printk("EX_TABLE: insn<%08lx> fixup<%08x> g2<%08lx>\n",
 341                                 regs->pc, fixup, g2);
 342 #endif
 343                         if ((regs->pc >= (unsigned long)__memset_start &&
 344                              regs->pc < (unsigned long)__memset_end) ||
 345                             (regs->pc >= (unsigned long)__csum_partial_copy_start &&
 346                              regs->pc < (unsigned long)__csum_partial_copy_end)) {
 347                                 regs->u_regs[UREG_I4] = address;
 348                                 regs->u_regs[UREG_I5] = regs->pc;
 349                         }
 350                         regs->u_regs[UREG_G2] = g2;
 351                         regs->pc = fixup;
 352                         regs->npc = regs->pc + 4;
 353                         return;
 354                 }
 355         }
 356
 357         unhandled_fault (address, tsk, regs);
 358         do_exit(SIGKILL);
 359
 360 /*
 361  * We ran out of memory, or some other thing happened to us that made
 362  * us unable to handle the page fault gracefully.
 363  */
 364 out_of_memory:
 365         up_read(&mm->mmap_sem);
 366         if (from_user) {
 367                 pagefault_out_of_memory();
 368                 return;
 369         }
 370         goto no_context;
 371
 372 do_sigbus:
 373         up_read(&mm->mmap_sem);
 374         do_fault_siginfo(BUS_ADRERR, SIGBUS, regs, text_fault);
 375         if (!from_user)
 376                 goto no_context;
 377
 378 vmalloc_fault:
 379         {
 380                 /*
 381                  * Synchronize this task's top level page-table
 382                  * with the 'reference' page table.
 383                  */
 384                 int offset = pgd_index(address);
 385                 pgd_t *pgd, *pgd_k;
 386                 pmd_t *pmd, *pmd_k;
 387
 388                 pgd = tsk->active_mm->pgd + offset;
 389                 pgd_k = init_mm.pgd + offset;
 390
 391                 if (!pgd_present(*pgd)) {
 392                         if (!pgd_present(*pgd_k))
 393                                 goto bad_area_nosemaphore;
 394                         pgd_val(*pgd) = pgd_val(*pgd_k);
 395                         return;
 396                 }
 397
 398                 pmd = pmd_offset(pgd, address);
 399                 pmd_k = pmd_offset(pgd_k, address);
 400
 401                 if (pmd_present(*pmd) || !pmd_present(*pmd_k))
 402                         goto bad_area_nosemaphore;
 403                 *pmd = *pmd_k;
 404                 return;
 405         }
 406 }
 407
 408 asmlinkage void do_sun4c_fault(struct pt_regs *regs, int text_fault, int write,
 409                                unsigned long address)
 410 {
 411         extern void sun4c_update_mmu_cache(struct vm_area_struct *,
 412                                            unsigned long,pte_t *);
 413         extern pte_t *sun4c_pte_offset_kernel(pmd_t *,unsigned long);
 414         struct task_struct *tsk = current;
 415         struct mm_struct *mm = tsk->mm;
 416         pgd_t *pgdp;
 417         pte_t *ptep;
 418
 419         if (text_fault) {
 420                 address = regs->pc;
 421         } else if (!write &&
 422                    !(regs->psr & PSR_PS)) {
 423                 unsigned int insn, __user *ip;
 424
 425                 ip = (unsigned int __user *)regs->pc;
 426                 if (!get_user(insn, ip)) {
 427                         if ((insn & 0xc1680000) == 0xc0680000)
 428                                 write = 1;
 429                 }
 430         }
 431
 432         if (!mm) {
 433                 /* We are oopsing. */
 434                 do_sparc_fault(regs, text_fault, write, address);
 435                 BUG();  /* P3 Oops already, you bitch */
 436         }
 437
 438         pgdp = pgd_offset(mm, address);
 439         ptep = sun4c_pte_offset_kernel((pmd_t *) pgdp, address);
 440
 441         if (pgd_val(*pgdp)) {
 442             if (write) {
 443                 if ((pte_val(*ptep) & (_SUN4C_PAGE_WRITE|_SUN4C_PAGE_PRESENT))
 444                                    == (_SUN4C_PAGE_WRITE|_SUN4C_PAGE_PRESENT)) {
 445                         unsigned long flags;
 446
 447                         *ptep = __pte(pte_val(*ptep) | _SUN4C_PAGE_ACCESSED |
 448                                       _SUN4C_PAGE_MODIFIED |
 449                                       _SUN4C_PAGE_VALID |
 450                                       _SUN4C_PAGE_DIRTY);
 451
 452                         local_irq_save(flags);
 453                         if (sun4c_get_segmap(address) != invalid_segment) {
 454                                 sun4c_put_pte(address, pte_val(*ptep));
 455                                 local_irq_restore(flags);
 456                                 return;
 457                         }
 458                         local_irq_restore(flags);
 459                 }
 460             } else {
 461                 if ((pte_val(*ptep) & (_SUN4C_PAGE_READ|_SUN4C_PAGE_PRESENT))
 462                                    == (_SUN4C_PAGE_READ|_SUN4C_PAGE_PRESENT)) {
 463                         unsigned long flags;
 464
 465                         *ptep = __pte(pte_val(*ptep) | _SUN4C_PAGE_ACCESSED |
 466                                       _SUN4C_PAGE_VALID);
 467
 468                         local_irq_save(flags);
 469                         if (sun4c_get_segmap(address) != invalid_segment) {
 470                                 sun4c_put_pte(address, pte_val(*ptep));
 471                                 local_irq_restore(flags);
 472                                 return;
 473                         }
 474                         local_irq_restore(flags);
 475                 }
 476             }
 477         }
 478
 479         /* This conditional is 'interesting'. */
 480         if (pgd_val(*pgdp) && !(write && !(pte_val(*ptep) & _SUN4C_PAGE_WRITE))
 481             && (pte_val(*ptep) & _SUN4C_PAGE_VALID))
 482                 /* Note: It is safe to not grab the MMAP semaphore here because
 483                  *       we know that update_mmu_cache() will not sleep for
 484                  *       any reason (at least not in the current implementation)
 485                  *       and therefore there is no danger of another thread getting
 486                  *       on the CPU and doing a shrink_mmap() on this vma.
 487                  */
 488                 sun4c_update_mmu_cache (find_vma(current->mm, address), address,
 489                                         ptep);
 490         else
 491                 do_sparc_fault(regs, text_fault, write, address);
 492 }
 493
 494 /* This always deals with user addresses. */
 495 static void force_user_fault(unsigned long address, int write)
 496 {
 497         struct vm_area_struct *vma;
 498         struct task_struct *tsk = current;
 499         struct mm_struct *mm = tsk->mm;
 500         int code;
 501
 502         code = SEGV_MAPERR;
 503
 504         down_read(&mm->mmap_sem);
 505         vma = find_vma(mm, address);
 506         if(!vma)
 507                 goto bad_area;
 508         if(vma->vm_start <= address)
 509                 goto good_area;
 510         if(!(vma->vm_flags & VM_GROWSDOWN))
 511                 goto bad_area;
 512         if(expand_stack(vma, address))
 513                 goto bad_area;
 514 good_area:
 515         code = SEGV_ACCERR;
 516         if(write) {
 517                 if(!(vma->vm_flags & VM_WRITE))
 518                         goto bad_area;
 519         } else {
 520                 if(!(vma->vm_flags & (VM_READ | VM_EXEC)))
 521                         goto bad_area;
 522         }
 523         switch (handle_mm_fault(mm, vma, address, write ? FAULT_FLAG_WRITE : 0)) {
 524         case VM_FAULT_SIGBUS:
 525         case VM_FAULT_OOM:
 526                 goto do_sigbus;
 527         }
 528         up_read(&mm->mmap_sem);
 529         return;
 530 bad_area:
 531         up_read(&mm->mmap_sem);
 532         __do_fault_siginfo(code, SIGSEGV, tsk->thread.kregs, address);
 533         return;
 534
 535 do_sigbus:
 536         up_read(&mm->mmap_sem);
 537         __do_fault_siginfo(BUS_ADRERR, SIGBUS, tsk->thread.kregs, address);
 538 }
 539
 540 static void check_stack_aligned(unsigned long sp)
 541 {
 542         if (sp & 0x7UL)
 543                 force_sig(SIGILL, current);
 544 }
 545
 546 void window_overflow_fault(void)
 547 {
 548         unsigned long sp;
 549
 550         sp = current_thread_info()->rwbuf_stkptrs[0];
 551         if(((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
 552                 force_user_fault(sp + 0x38, 1);
 553         force_user_fault(sp, 1);
 554
 555         check_stack_aligned(sp);
 556 }
 557
 558 void window_underflow_fault(unsigned long sp)
 559 {
 560         if(((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
 561                 force_user_fault(sp + 0x38, 0);
 562         force_user_fault(sp, 0);
 563
 564         check_stack_aligned(sp);
 565 }
 566
 567 void window_ret_fault(struct pt_regs *regs)
 568 {
 569         unsigned long sp;
 570
 571         sp = regs->u_regs[UREG_FP];
 572         if(((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
 573                 force_user_fault(sp + 0x38, 0);
 574         force_user_fault(sp, 0);
 575
 576         check_stack_aligned(sp);
 577 }