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_SIGBUS)
 298                         goto do_sigbus;
 299                 BUG();
 300         }
 301         if (fault & VM_FAULT_MAJOR) {
 302                 current->maj_flt++;
 303                 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs, address);
 304         } else {
 305                 current->min_flt++;
 306                 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs, address);
 307         }
 308         up_read(&mm->mmap_sem);
 309         return;
 310
 311         /*
 312          * Something tried to access memory that isn't in our memory map..
 313          * Fix it, but check if it's kernel or user first..
 314          */
 315 bad_area:
 316         up_read(&mm->mmap_sem);
 317
 318 bad_area_nosemaphore:
 319         /* User mode accesses just cause a SIGSEGV */
 320         if (from_user) {
 321                 do_fault_siginfo(code, SIGSEGV, regs, text_fault);
 322                 return;
 323         }
 324
 325         /* Is this in ex_table? */
 326 no_context:
 327         g2 = regs->u_regs[UREG_G2];
 328         if (!from_user) {
 329                 fixup = search_extables_range(regs->pc, &g2);
 330                 if (fixup > 10) { /* Values below are reserved for other things */
 331                         extern const unsigned __memset_start[];
 332                         extern const unsigned __memset_end[];
 333                         extern const unsigned __csum_partial_copy_start[];
 334                         extern const unsigned __csum_partial_copy_end[];
 335
 336 #ifdef DEBUG_EXCEPTIONS
 337                         printk("Exception: PC<%08lx> faddr<%08lx>\n", regs->pc, address);
 338                         printk("EX_TABLE: insn<%08lx> fixup<%08x> g2<%08lx>\n",
 339                                 regs->pc, fixup, g2);
 340 #endif
 341                         if ((regs->pc >= (unsigned long)__memset_start &&
 342                              regs->pc < (unsigned long)__memset_end) ||
 343                             (regs->pc >= (unsigned long)__csum_partial_copy_start &&
 344                              regs->pc < (unsigned long)__csum_partial_copy_end)) {
 345                                 regs->u_regs[UREG_I4] = address;
 346                                 regs->u_regs[UREG_I5] = regs->pc;
 347                         }
 348                         regs->u_regs[UREG_G2] = g2;
 349                         regs->pc = fixup;
 350                         regs->npc = regs->pc + 4;
 351                         return;
 352                 }
 353         }
 354
 355         unhandled_fault (address, tsk, regs);
 356         do_exit(SIGKILL);
 357
 358 /*
 359  * We ran out of memory, or some other thing happened to us that made
 360  * us unable to handle the page fault gracefully.
 361  */
 362 out_of_memory:
 363         up_read(&mm->mmap_sem);
 364         if (from_user) {
 365                 pagefault_out_of_memory();
 366                 return;
 367         }
 368         goto no_context;
 369
 370 do_sigbus:
 371         up_read(&mm->mmap_sem);
 372         do_fault_siginfo(BUS_ADRERR, SIGBUS, regs, text_fault);
 373         if (!from_user)
 374                 goto no_context;
 375
 376 vmalloc_fault:
 377         {
 378                 /*
 379                  * Synchronize this task's top level page-table
 380                  * with the 'reference' page table.
 381                  */
 382                 int offset = pgd_index(address);
 383                 pgd_t *pgd, *pgd_k;
 384                 pmd_t *pmd, *pmd_k;
 385
 386                 pgd = tsk->active_mm->pgd + offset;
 387                 pgd_k = init_mm.pgd + offset;
 388
 389                 if (!pgd_present(*pgd)) {
 390                         if (!pgd_present(*pgd_k))
 391                                 goto bad_area_nosemaphore;
 392                         pgd_val(*pgd) = pgd_val(*pgd_k);
 393                         return;
 394                 }
 395
 396                 pmd = pmd_offset(pgd, address);
 397                 pmd_k = pmd_offset(pgd_k, address);
 398
 399                 if (pmd_present(*pmd) || !pmd_present(*pmd_k))
 400                         goto bad_area_nosemaphore;
 401                 *pmd = *pmd_k;
 402                 return;
 403         }
 404 }
 405
 406 asmlinkage void do_sun4c_fault(struct pt_regs *regs, int text_fault, int write,
 407                                unsigned long address)
 408 {
 409         extern void sun4c_update_mmu_cache(struct vm_area_struct *,
 410                                            unsigned long,pte_t *);
 411         extern pte_t *sun4c_pte_offset_kernel(pmd_t *,unsigned long);
 412         struct task_struct *tsk = current;
 413         struct mm_struct *mm = tsk->mm;
 414         pgd_t *pgdp;
 415         pte_t *ptep;
 416
 417         if (text_fault) {
 418                 address = regs->pc;
 419         } else if (!write &&
 420                    !(regs->psr & PSR_PS)) {
 421                 unsigned int insn, __user *ip;
 422
 423                 ip = (unsigned int __user *)regs->pc;
 424                 if (!get_user(insn, ip)) {
 425                         if ((insn & 0xc1680000) == 0xc0680000)
 426                                 write = 1;
 427                 }
 428         }
 429
 430         if (!mm) {
 431                 /* We are oopsing. */
 432                 do_sparc_fault(regs, text_fault, write, address);
 433                 BUG();  /* P3 Oops already, you bitch */
 434         }
 435
 436         pgdp = pgd_offset(mm, address);
 437         ptep = sun4c_pte_offset_kernel((pmd_t *) pgdp, address);
 438
 439         if (pgd_val(*pgdp)) {
 440             if (write) {
 441                 if ((pte_val(*ptep) & (_SUN4C_PAGE_WRITE|_SUN4C_PAGE_PRESENT))
 442                                    == (_SUN4C_PAGE_WRITE|_SUN4C_PAGE_PRESENT)) {
 443                         unsigned long flags;
 444
 445                         *ptep = __pte(pte_val(*ptep) | _SUN4C_PAGE_ACCESSED |
 446                                       _SUN4C_PAGE_MODIFIED |
 447                                       _SUN4C_PAGE_VALID |
 448                                       _SUN4C_PAGE_DIRTY);
 449
 450                         local_irq_save(flags);
 451                         if (sun4c_get_segmap(address) != invalid_segment) {
 452                                 sun4c_put_pte(address, pte_val(*ptep));
 453                                 local_irq_restore(flags);
 454                                 return;
 455                         }
 456                         local_irq_restore(flags);
 457                 }
 458             } else {
 459                 if ((pte_val(*ptep) & (_SUN4C_PAGE_READ|_SUN4C_PAGE_PRESENT))
 460                                    == (_SUN4C_PAGE_READ|_SUN4C_PAGE_PRESENT)) {
 461                         unsigned long flags;
 462
 463                         *ptep = __pte(pte_val(*ptep) | _SUN4C_PAGE_ACCESSED |
 464                                       _SUN4C_PAGE_VALID);
 465
 466                         local_irq_save(flags);
 467                         if (sun4c_get_segmap(address) != invalid_segment) {
 468                                 sun4c_put_pte(address, pte_val(*ptep));
 469                                 local_irq_restore(flags);
 470                                 return;
 471                         }
 472                         local_irq_restore(flags);
 473                 }
 474             }
 475         }
 476
 477         /* This conditional is 'interesting'. */
 478         if (pgd_val(*pgdp) && !(write && !(pte_val(*ptep) & _SUN4C_PAGE_WRITE))
 479             && (pte_val(*ptep) & _SUN4C_PAGE_VALID))
 480                 /* Note: It is safe to not grab the MMAP semaphore here because
 481                  *       we know that update_mmu_cache() will not sleep for
 482                  *       any reason (at least not in the current implementation)
 483                  *       and therefore there is no danger of another thread getting
 484                  *       on the CPU and doing a shrink_mmap() on this vma.
 485                  */
 486                 sun4c_update_mmu_cache (find_vma(current->mm, address), address,
 487                                         ptep);
 488         else
 489                 do_sparc_fault(regs, text_fault, write, address);
 490 }
 491
 492 /* This always deals with user addresses. */
 493 static void force_user_fault(unsigned long address, int write)
 494 {
 495         struct vm_area_struct *vma;
 496         struct task_struct *tsk = current;
 497         struct mm_struct *mm = tsk->mm;
 498         int code;
 499
 500         code = SEGV_MAPERR;
 501
 502         down_read(&mm->mmap_sem);
 503         vma = find_vma(mm, address);
 504         if(!vma)
 505                 goto bad_area;
 506         if(vma->vm_start <= address)
 507                 goto good_area;
 508         if(!(vma->vm_flags & VM_GROWSDOWN))
 509                 goto bad_area;
 510         if(expand_stack(vma, address))
 511                 goto bad_area;
 512 good_area:
 513         code = SEGV_ACCERR;
 514         if(write) {
 515                 if(!(vma->vm_flags & VM_WRITE))
 516                         goto bad_area;
 517         } else {
 518                 if(!(vma->vm_flags & (VM_READ | VM_EXEC)))
 519                         goto bad_area;
 520         }
 521         switch (handle_mm_fault(mm, vma, address, write ? FAULT_FLAG_WRITE : 0)) {
 522         case VM_FAULT_SIGBUS:
 523         case VM_FAULT_OOM:
 524                 goto do_sigbus;
 525         }
 526         up_read(&mm->mmap_sem);
 527         return;
 528 bad_area:
 529         up_read(&mm->mmap_sem);
 530         __do_fault_siginfo(code, SIGSEGV, tsk->thread.kregs, address);
 531         return;
 532
 533 do_sigbus:
 534         up_read(&mm->mmap_sem);
 535         __do_fault_siginfo(BUS_ADRERR, SIGBUS, tsk->thread.kregs, address);
 536 }
 537
 538 static void check_stack_aligned(unsigned long sp)
 539 {
 540         if (sp & 0x7UL)
 541                 force_sig(SIGILL, current);
 542 }
 543
 544 void window_overflow_fault(void)
 545 {
 546         unsigned long sp;
 547
 548         sp = current_thread_info()->rwbuf_stkptrs[0];
 549         if(((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
 550                 force_user_fault(sp + 0x38, 1);
 551         force_user_fault(sp, 1);
 552
 553         check_stack_aligned(sp);
 554 }
 555
 556 void window_underflow_fault(unsigned long sp)
 557 {
 558         if(((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
 559                 force_user_fault(sp + 0x38, 0);
 560         force_user_fault(sp, 0);
 561
 562         check_stack_aligned(sp);
 563 }
 564
 565 void window_ret_fault(struct pt_regs *regs)
 566 {
 567         unsigned long sp;
 568
 569         sp = regs->u_regs[UREG_FP];
 570         if(((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
 571                 force_user_fault(sp + 0x38, 0);
 572         force_user_fault(sp, 0);
 573
 574         check_stack_aligned(sp);
 575 }