arch/sparc64/mm/fault.c

   1 /* $Id: fault.c,v 1.59 2002/02/09 19:49:31 davem Exp $
   2  * arch/sparc64/mm/fault.c: Page fault handlers for the 64-bit Sparc.
   3  *
   4  * Copyright (C) 1996 David S. Miller (davem@caip.rutgers.edu)
   5  * Copyright (C) 1997, 1999 Jakub Jelinek (jj@ultra.linux.cz)
   6  */
   7
   8 #include <asm/head.h>
   9
  10 #include <linux/string.h>
  11 #include <linux/types.h>
  12 #include <linux/sched.h>
  13 #include <linux/ptrace.h>
  14 #include <linux/mman.h>
  15 #include <linux/signal.h>
  16 #include <linux/mm.h>
  17 #include <linux/module.h>
  18 #include <linux/smp_lock.h>
  19 #include <linux/init.h>
  20 #include <linux/interrupt.h>
  21 #include <linux/kprobes.h>
  22
  23 #include <asm/page.h>
  24 #include <asm/pgtable.h>
  25 #include <asm/openprom.h>
  26 #include <asm/oplib.h>
  27 #include <asm/uaccess.h>
  28 #include <asm/asi.h>
  29 #include <asm/lsu.h>
  30 #include <asm/sections.h>
  31 #include <asm/kdebug.h>
  32
  33 #define ELEMENTS(arr) (sizeof (arr)/sizeof (arr[0]))
  34
  35 extern struct sparc_phys_banks sp_banks[SPARC_PHYS_BANKS];
  36
  37 /*
  38  * To debug kernel to catch accesses to certain virtual/physical addresses.
  39  * Mode = 0 selects physical watchpoints, mode = 1 selects virtual watchpoints.
  40  * flags = VM_READ watches memread accesses, flags = VM_WRITE watches memwrite accesses.
  41  * Caller passes in a 64bit aligned addr, with mask set to the bytes that need to be
  42  * watched. This is only useful on a single cpu machine for now. After the watchpoint
  43  * is detected, the process causing it will be killed, thus preventing an infinite loop.
  44  */
  45 void set_brkpt(unsigned long addr, unsigned char mask, int flags, int mode)
  46 {
  47         unsigned long lsubits;
  48
  49         __asm__ __volatile__("ldxa [%%g0] %1, %0"
  50                              : "=r" (lsubits)
  51                              : "i" (ASI_LSU_CONTROL));
  52         lsubits &= ~(LSU_CONTROL_PM | LSU_CONTROL_VM |
  53                      LSU_CONTROL_PR | LSU_CONTROL_VR |
  54                      LSU_CONTROL_PW | LSU_CONTROL_VW);
  55
  56         __asm__ __volatile__("stxa      %0, [%1] %2\n\t"
  57                              "membar    #Sync"
  58                              : /* no outputs */
  59                              : "r" (addr), "r" (mode ? VIRT_WATCHPOINT : PHYS_WATCHPOINT),
  60                                "i" (ASI_DMMU));
  61
  62         lsubits |= ((unsigned long)mask << (mode ? 25 : 33));
  63         if (flags & VM_READ)
  64                 lsubits |= (mode ? LSU_CONTROL_VR : LSU_CONTROL_PR);
  65         if (flags & VM_WRITE)
  66                 lsubits |= (mode ? LSU_CONTROL_VW : LSU_CONTROL_PW);
  67         __asm__ __volatile__("stxa %0, [%%g0] %1\n\t"
  68                              "membar #Sync"
  69                              : /* no outputs */
  70                              : "r" (lsubits), "i" (ASI_LSU_CONTROL)
  71                              : "memory");
  72 }
  73
  74 /* Nice, simple, prom library does all the sweating for us. ;) */
  75 unsigned long __init prom_probe_memory (void)
  76 {
  77         register struct linux_mlist_p1275 *mlist;
  78         register unsigned long bytes, base_paddr, tally;
  79         register int i;
  80
  81         i = 0;
  82         mlist = *prom_meminfo()->p1275_available;
  83         bytes = tally = mlist->num_bytes;
  84         base_paddr = mlist->start_adr;
  85
  86         sp_banks[0].base_addr = base_paddr;
  87         sp_banks[0].num_bytes = bytes;
  88
  89         while (mlist->theres_more != (void *) 0) {
  90                 i++;
  91                 mlist = mlist->theres_more;
  92                 bytes = mlist->num_bytes;
  93                 tally += bytes;
  94                 if (i >= SPARC_PHYS_BANKS-1) {
  95                         printk ("The machine has more banks than "
  96                                 "this kernel can support\n"
  97                                 "Increase the SPARC_PHYS_BANKS "
  98                                 "setting (currently %d)\n",
  99                                 SPARC_PHYS_BANKS);
 100                         i = SPARC_PHYS_BANKS-1;
 101                         break;
 102                 }
 103
 104                 sp_banks[i].base_addr = mlist->start_adr;
 105                 sp_banks[i].num_bytes = mlist->num_bytes;
 106         }
 107
 108         i++;
 109         sp_banks[i].base_addr = 0xdeadbeefbeefdeadUL;
 110         sp_banks[i].num_bytes = 0;
 111
 112         /* Now mask all bank sizes on a page boundary, it is all we can
 113          * use anyways.
 114          */
 115         for (i = 0; sp_banks[i].num_bytes != 0; i++)
 116                 sp_banks[i].num_bytes &= PAGE_MASK;
 117
 118         return tally;
 119 }
 120
 121 static void __kprobes unhandled_fault(unsigned long address,
 122                                       struct task_struct *tsk,
 123                                       struct pt_regs *regs)
 124 {
 125         if ((unsigned long) address < PAGE_SIZE) {
 126                 printk(KERN_ALERT "Unable to handle kernel NULL "
 127                        "pointer dereference\n");
 128         } else {
 129                 printk(KERN_ALERT "Unable to handle kernel paging request "
 130                        "at virtual address %016lx\n", (unsigned long)address);
 131         }
 132         printk(KERN_ALERT "tsk->{mm,active_mm}->context = %016lx\n",
 133                (tsk->mm ?
 134                 CTX_HWBITS(tsk->mm->context) :
 135                 CTX_HWBITS(tsk->active_mm->context)));
 136         printk(KERN_ALERT "tsk->{mm,active_mm}->pgd = %016lx\n",
 137                (tsk->mm ? (unsigned long) tsk->mm->pgd :
 138                           (unsigned long) tsk->active_mm->pgd));
 139         if (notify_die(DIE_GPF, "general protection fault", regs,
 140                        0, 0, SIGSEGV) == NOTIFY_STOP)
 141                 return;
 142         die_if_kernel("Oops", regs);
 143 }
 144
 145 static void bad_kernel_pc(struct pt_regs *regs)
 146 {
 147         unsigned long *ksp;
 148
 149         printk(KERN_CRIT "OOPS: Bogus kernel PC [%016lx] in fault handler\n",
 150                regs->tpc);
 151         __asm__("mov %%sp, %0" : "=r" (ksp));
 152         show_stack(current, ksp);
 153         unhandled_fault(regs->tpc, current, regs);
 154 }
 155
 156 /*
 157  * We now make sure that mmap_sem is held in all paths that call
 158  * this. Additionally, to prevent kswapd from ripping ptes from
 159  * under us, raise interrupts around the time that we look at the
 160  * pte, kswapd will have to wait to get his smp ipi response from
 161  * us. This saves us having to get page_table_lock.
 162  */
 163 static unsigned int get_user_insn(unsigned long tpc)
 164 {
 165         pgd_t *pgdp = pgd_offset(current->mm, tpc);
 166         pud_t *pudp;
 167         pmd_t *pmdp;
 168         pte_t *ptep, pte;
 169         unsigned long pa;
 170         u32 insn = 0;
 171         unsigned long pstate;
 172
 173         if (pgd_none(*pgdp))
 174                 goto outret;
 175         pudp = pud_offset(pgdp, tpc);
 176         if (pud_none(*pudp))
 177                 goto outret;
 178         pmdp = pmd_offset(pudp, tpc);
 179         if (pmd_none(*pmdp))
 180                 goto outret;
 181
 182         /* This disables preemption for us as well. */
 183         __asm__ __volatile__("rdpr %%pstate, %0" : "=r" (pstate));
 184         __asm__ __volatile__("wrpr %0, %1, %%pstate"
 185                                 : : "r" (pstate), "i" (PSTATE_IE));
 186         ptep = pte_offset_map(pmdp, tpc);
 187         pte = *ptep;
 188         if (!pte_present(pte))
 189                 goto out;
 190
 191         pa  = (pte_val(pte) & _PAGE_PADDR);
 192         pa += (tpc & ~PAGE_MASK);
 193
 194         /* Use phys bypass so we don't pollute dtlb/dcache. */
 195         __asm__ __volatile__("lduwa [%1] %2, %0"
 196                              : "=r" (insn)
 197                              : "r" (pa), "i" (ASI_PHYS_USE_EC));
 198
 199 out:
 200         pte_unmap(ptep);
 201         __asm__ __volatile__("wrpr %0, 0x0, %%pstate" : : "r" (pstate));
 202 outret:
 203         return insn;
 204 }
 205
 206 extern unsigned long compute_effective_address(struct pt_regs *, unsigned int, unsigned int);
 207
 208 static void do_fault_siginfo(int code, int sig, struct pt_regs *regs,
 209                              unsigned int insn, int fault_code)
 210 {
 211         siginfo_t info;
 212
 213         info.si_code = code;
 214         info.si_signo = sig;
 215         info.si_errno = 0;
 216         if (fault_code & FAULT_CODE_ITLB)
 217                 info.si_addr = (void __user *) regs->tpc;
 218         else
 219                 info.si_addr = (void __user *)
 220                         compute_effective_address(regs, insn, 0);
 221         info.si_trapno = 0;
 222         force_sig_info(sig, &info, current);
 223 }
 224
 225 extern int handle_ldf_stq(u32, struct pt_regs *);
 226 extern int handle_ld_nf(u32, struct pt_regs *);
 227
 228 static unsigned int get_fault_insn(struct pt_regs *regs, unsigned int insn)
 229 {
 230         if (!insn) {
 231                 if (!regs->tpc || (regs->tpc & 0x3))
 232                         return 0;
 233                 if (regs->tstate & TSTATE_PRIV) {
 234                         insn = *(unsigned int *) regs->tpc;
 235                 } else {
 236                         insn = get_user_insn(regs->tpc);
 237                 }
 238         }
 239         return insn;
 240 }
 241
 242 static void do_kernel_fault(struct pt_regs *regs, int si_code, int fault_code,
 243                             unsigned int insn, unsigned long address)
 244 {
 245         unsigned char asi = ASI_P;
 246
 247         if ((!insn) && (regs->tstate & TSTATE_PRIV))
 248                 goto cannot_handle;
 249
 250         /* If user insn could be read (thus insn is zero), that
 251          * is fine.  We will just gun down the process with a signal
 252          * in that case.
 253          */
 254
 255         if (!(fault_code & (FAULT_CODE_WRITE|FAULT_CODE_ITLB)) &&
 256             (insn & 0xc0800000) == 0xc0800000) {
 257                 if (insn & 0x2000)
 258                         asi = (regs->tstate >> 24);
 259                 else
 260                         asi = (insn >> 5);
 261                 if ((asi & 0xf2) == 0x82) {
 262                         if (insn & 0x1000000) {
 263                                 handle_ldf_stq(insn, regs);
 264                         } else {
 265                                 /* This was a non-faulting load. Just clear the
 266                                  * destination register(s) and continue with the next
 267                                  * instruction. -jj
 268                                  */
 269                                 handle_ld_nf(insn, regs);
 270                         }
 271                         return;
 272                 }
 273         }
 274
 275         /* Is this in ex_table? */
 276         if (regs->tstate & TSTATE_PRIV) {
 277                 const struct exception_table_entry *entry;
 278
 279                 if (asi == ASI_P && (insn & 0xc0800000) == 0xc0800000) {
 280                         if (insn & 0x2000)
 281                                 asi = (regs->tstate >> 24);
 282                         else
 283                                 asi = (insn >> 5);
 284                 }
 285
 286                 /* Look in asi.h: All _S asis have LS bit set */
 287                 if ((asi & 0x1) &&
 288                     (entry = search_exception_tables(regs->tpc))) {
 289                         regs->tpc = entry->fixup;
 290                         regs->tnpc = regs->tpc + 4;
 291                         return;
 292                 }
 293         } else {
 294                 /* The si_code was set to make clear whether
 295                  * this was a SEGV_MAPERR or SEGV_ACCERR fault.
 296                  */
 297                 do_fault_siginfo(si_code, SIGSEGV, regs, insn, fault_code);
 298                 return;
 299         }
 300
 301 cannot_handle:
 302         unhandled_fault (address, current, regs);
 303 }
 304
 305 asmlinkage void __kprobes do_sparc64_fault(struct pt_regs *regs)
 306 {
 307         struct mm_struct *mm = current->mm;
 308         struct vm_area_struct *vma;
 309         unsigned int insn = 0;
 310         int si_code, fault_code;
 311         unsigned long address;
 312
 313         fault_code = get_thread_fault_code();
 314
 315         if (notify_die(DIE_PAGE_FAULT, "page_fault", regs,
 316                        fault_code, 0, SIGSEGV) == NOTIFY_STOP)
 317                 return;
 318
 319         si_code = SEGV_MAPERR;
 320         address = current_thread_info()->fault_address;
 321
 322         if ((fault_code & FAULT_CODE_ITLB) &&
 323             (fault_code & FAULT_CODE_DTLB))
 324                 BUG();
 325
 326         if (regs->tstate & TSTATE_PRIV) {
 327                 unsigned long tpc = regs->tpc;
 328
 329                 /* Sanity check the PC. */
 330                 if ((tpc >= KERNBASE && tpc < (unsigned long) _etext) ||
 331                     (tpc >= MODULES_VADDR && tpc < MODULES_END)) {
 332                         /* Valid, no problems... */
 333                 } else {
 334                         bad_kernel_pc(regs);
 335                         return;
 336                 }
 337         }
 338
 339         /*
 340          * If we're in an interrupt or have no user
 341          * context, we must not take the fault..
 342          */
 343         if (in_atomic() || !mm)
 344                 goto intr_or_no_mm;
 345
 346         if (test_thread_flag(TIF_32BIT)) {
 347                 if (!(regs->tstate & TSTATE_PRIV))
 348                         regs->tpc &= 0xffffffff;
 349                 address &= 0xffffffff;
 350         }
 351
 352         if (!down_read_trylock(&mm->mmap_sem)) {
 353                 if ((regs->tstate & TSTATE_PRIV) &&
 354                     !search_exception_tables(regs->tpc)) {
 355                         insn = get_fault_insn(regs, insn);
 356                         goto handle_kernel_fault;
 357                 }
 358                 down_read(&mm->mmap_sem);
 359         }
 360
 361         vma = find_vma(mm, address);
 362         if (!vma)
 363                 goto bad_area;
 364
 365         /* Pure DTLB misses do not tell us whether the fault causing
 366          * load/store/atomic was a write or not, it only says that there
 367          * was no match.  So in such a case we (carefully) read the
 368          * instruction to try and figure this out.  It's an optimization
 369          * so it's ok if we can't do this.
 370          *
 371          * Special hack, window spill/fill knows the exact fault type.
 372          */
 373         if (((fault_code &
 374               (FAULT_CODE_DTLB | FAULT_CODE_WRITE | FAULT_CODE_WINFIXUP)) == FAULT_CODE_DTLB) &&
 375             (vma->vm_flags & VM_WRITE) != 0) {
 376                 insn = get_fault_insn(regs, 0);
 377                 if (!insn)
 378                         goto continue_fault;
 379                 if ((insn & 0xc0200000) == 0xc0200000 &&
 380                     (insn & 0x1780000) != 0x1680000) {
 381                         /* Don't bother updating thread struct value,
 382                          * because update_mmu_cache only cares which tlb
 383                          * the access came from.
 384                          */
 385                         fault_code |= FAULT_CODE_WRITE;
 386                 }
 387         }
 388 continue_fault:
 389
 390         if (vma->vm_start <= address)
 391                 goto good_area;
 392         if (!(vma->vm_flags & VM_GROWSDOWN))
 393                 goto bad_area;
 394         if (!(fault_code & FAULT_CODE_WRITE)) {
 395                 /* Non-faulting loads shouldn't expand stack. */
 396                 insn = get_fault_insn(regs, insn);
 397                 if ((insn & 0xc0800000) == 0xc0800000) {
 398                         unsigned char asi;
 399
 400                         if (insn & 0x2000)
 401                                 asi = (regs->tstate >> 24);
 402                         else
 403                                 asi = (insn >> 5);
 404                         if ((asi & 0xf2) == 0x82)
 405                                 goto bad_area;
 406                 }
 407         }
 408         if (expand_stack(vma, address))
 409                 goto bad_area;
 410         /*
 411          * Ok, we have a good vm_area for this memory access, so
 412          * we can handle it..
 413          */
 414 good_area:
 415         si_code = SEGV_ACCERR;
 416
 417         /* If we took a ITLB miss on a non-executable page, catch
 418          * that here.
 419          */
 420         if ((fault_code & FAULT_CODE_ITLB) && !(vma->vm_flags & VM_EXEC)) {
 421                 BUG_ON(address != regs->tpc);
 422                 BUG_ON(regs->tstate & TSTATE_PRIV);
 423                 goto bad_area;
 424         }
 425
 426         if (fault_code & FAULT_CODE_WRITE) {
 427                 if (!(vma->vm_flags & VM_WRITE))
 428                         goto bad_area;
 429
 430                 /* Spitfire has an icache which does not snoop
 431                  * processor stores.  Later processors do...
 432                  */
 433                 if (tlb_type == spitfire &&
 434                     (vma->vm_flags & VM_EXEC) != 0 &&
 435                     vma->vm_file != NULL)
 436                         set_thread_fault_code(fault_code |
 437                                               FAULT_CODE_BLKCOMMIT);
 438         } else {
 439                 /* Allow reads even for write-only mappings */
 440                 if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
 441                         goto bad_area;
 442         }
 443
 444         switch (handle_mm_fault(mm, vma, address, (fault_code & FAULT_CODE_WRITE))) {
 445         case VM_FAULT_MINOR:
 446                 current->min_flt++;
 447                 break;
 448         case VM_FAULT_MAJOR:
 449                 current->maj_flt++;
 450                 break;
 451         case VM_FAULT_SIGBUS:
 452                 goto do_sigbus;
 453         case VM_FAULT_OOM:
 454                 goto out_of_memory;
 455         default:
 456                 BUG();
 457         }
 458
 459         up_read(&mm->mmap_sem);
 460         goto fault_done;
 461
 462         /*
 463          * Something tried to access memory that isn't in our memory map..
 464          * Fix it, but check if it's kernel or user first..
 465          */
 466 bad_area:
 467         insn = get_fault_insn(regs, insn);
 468         up_read(&mm->mmap_sem);
 469
 470 handle_kernel_fault:
 471         do_kernel_fault(regs, si_code, fault_code, insn, address);
 472
 473         goto fault_done;
 474
 475 /*
 476  * We ran out of memory, or some other thing happened to us that made
 477  * us unable to handle the page fault gracefully.
 478  */
 479 out_of_memory:
 480         insn = get_fault_insn(regs, insn);
 481         up_read(&mm->mmap_sem);
 482         printk("VM: killing process %s\n", current->comm);
 483         if (!(regs->tstate & TSTATE_PRIV))
 484                 do_exit(SIGKILL);
 485         goto handle_kernel_fault;
 486
 487 intr_or_no_mm:
 488         insn = get_fault_insn(regs, 0);
 489         goto handle_kernel_fault;
 490
 491 do_sigbus:
 492         insn = get_fault_insn(regs, insn);
 493         up_read(&mm->mmap_sem);
 494
 495         /*
 496          * Send a sigbus, regardless of whether we were in kernel
 497          * or user mode.
 498          */
 499         do_fault_siginfo(BUS_ADRERR, SIGBUS, regs, insn, fault_code);
 500
 501         /* Kernel mode? Handle exceptions or die */
 502         if (regs->tstate & TSTATE_PRIV)
 503                 goto handle_kernel_fault;
 504
 505 fault_done:
 506         /* These values are no longer needed, clear them. */
 507         set_thread_fault_code(0);
 508         current_thread_info()->fault_address = 0;
 509 }