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/openprom.h>
  28 #include <asm/oplib.h>
  29 #include <asm/smp.h>
  30 #include <asm/traps.h>
  31 #include <asm/uaccess.h>
  32
  33 extern int prom_node_root;
  34
  35 int show_unhandled_signals = 1;
  36
  37 /* At boot time we determine these two values necessary for setting
  38  * up the segment maps and page table entries (pte's).
  39  */
  40
  41 int num_segmaps, num_contexts;
  42 int invalid_segment;
  43
  44 /* various Virtual Address Cache parameters we find at boot time... */
  45
  46 int vac_size, vac_linesize, vac_do_hw_vac_flushes;
  47 int vac_entries_per_context, vac_entries_per_segment;
  48 int vac_entries_per_page;
  49
  50 /* Return how much physical memory we have.  */
  51 unsigned long probe_memory(void)
  52 {
  53         unsigned long total = 0;
  54         int i;
  55
  56         for (i = 0; sp_banks[i].num_bytes; i++)
  57                 total += sp_banks[i].num_bytes;
  58
  59         return total;
  60 }
  61
  62 static void unhandled_fault(unsigned long, struct task_struct *,
  63                 struct pt_regs *) __attribute__ ((noreturn));
  64
  65 static void unhandled_fault(unsigned long address, struct task_struct *tsk,
  66                      struct pt_regs *regs)
  67 {
  68         if((unsigned long) address < PAGE_SIZE) {
  69                 printk(KERN_ALERT
  70                     "Unable to handle kernel NULL pointer dereference\n");
  71         } else {
  72                 printk(KERN_ALERT "Unable to handle kernel paging request "
  73                        "at virtual address %08lx\n", address);
  74         }
  75         printk(KERN_ALERT "tsk->{mm,active_mm}->context = %08lx\n",
  76                 (tsk->mm ? tsk->mm->context : tsk->active_mm->context));
  77         printk(KERN_ALERT "tsk->{mm,active_mm}->pgd = %08lx\n",
  78                 (tsk->mm ? (unsigned long) tsk->mm->pgd :
  79                         (unsigned long) tsk->active_mm->pgd));
  80         die_if_kernel("Oops", regs);
  81 }
  82
  83 asmlinkage int lookup_fault(unsigned long pc, unsigned long ret_pc,
  84                             unsigned long address)
  85 {
  86         struct pt_regs regs;
  87         unsigned long g2;
  88         unsigned int insn;
  89         int i;
  90
  91         i = search_extables_range(ret_pc, &g2);
  92         switch (i) {
  93         case 3:
  94                 /* load & store will be handled by fixup */
  95                 return 3;
  96
  97         case 1:
  98                 /* store will be handled by fixup, load will bump out */
  99                 /* for _to_ macros */
 100                 insn = *((unsigned int *) pc);
 101                 if ((insn >> 21) & 1)
 102                         return 1;
 103                 break;
 104
 105         case 2:
 106                 /* load will be handled by fixup, store will bump out */
 107                 /* for _from_ macros */
 108                 insn = *((unsigned int *) pc);
 109                 if (!((insn >> 21) & 1) || ((insn>>19)&0x3f) == 15)
 110                         return 2;
 111                 break;
 112
 113         default:
 114                 break;
 115         }
 116
 117         memset(&regs, 0, sizeof (regs));
 118         regs.pc = pc;
 119         regs.npc = pc + 4;
 120         __asm__ __volatile__(
 121                 "rd %%psr, %0\n\t"
 122                 "nop\n\t"
 123                 "nop\n\t"
 124                 "nop\n" : "=r" (regs.psr));
 125         unhandled_fault(address, current, &regs);
 126
 127         /* Not reached */
 128         return 0;
 129 }
 130
 131 static inline void
 132 show_signal_msg(struct pt_regs *regs, int sig, int code,
 133                 unsigned long address, struct task_struct *tsk)
 134 {
 135         if (!unhandled_signal(tsk, sig))
 136                 return;
 137
 138         if (!printk_ratelimit())
 139                 return;
 140
 141         printk("%s%s[%d]: segfault at %lx ip %p (rpc %p) sp %p error %x",
 142                task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
 143                tsk->comm, task_pid_nr(tsk), address,
 144                (void *)regs->pc, (void *)regs->u_regs[UREG_I7],
 145                (void *)regs->u_regs[UREG_FP], code);
 146
 147         print_vma_addr(KERN_CONT " in ", regs->pc);
 148
 149         printk(KERN_CONT "\n");
 150 }
 151
 152 static void __do_fault_siginfo(int code, int sig, struct pt_regs *regs,
 153                                unsigned long addr)
 154 {
 155         siginfo_t info;
 156
 157         info.si_signo = sig;
 158         info.si_code = code;
 159         info.si_errno = 0;
 160         info.si_addr = (void __user *) addr;
 161         info.si_trapno = 0;
 162
 163         if (unlikely(show_unhandled_signals))
 164                 show_signal_msg(regs, sig, info.si_code,
 165                                 addr, current);
 166
 167         force_sig_info (sig, &info, current);
 168 }
 169
 170 extern unsigned long safe_compute_effective_address(struct pt_regs *,
 171                                                     unsigned int);
 172
 173 static unsigned long compute_si_addr(struct pt_regs *regs, int text_fault)
 174 {
 175         unsigned int insn;
 176
 177         if (text_fault)
 178                 return regs->pc;
 179
 180         if (regs->psr & PSR_PS) {
 181                 insn = *(unsigned int *) regs->pc;
 182         } else {
 183                 __get_user(insn, (unsigned int *) regs->pc);
 184         }
 185
 186         return safe_compute_effective_address(regs, insn);
 187 }
 188
 189 static noinline void do_fault_siginfo(int code, int sig, struct pt_regs *regs,
 190                                       int text_fault)
 191 {
 192         unsigned long addr = compute_si_addr(regs, text_fault);
 193
 194         __do_fault_siginfo(code, sig, regs, addr);
 195 }
 196
 197 asmlinkage void do_sparc_fault(struct pt_regs *regs, int text_fault, int write,
 198                                unsigned long address)
 199 {
 200         struct vm_area_struct *vma;
 201         struct task_struct *tsk = current;
 202         struct mm_struct *mm = tsk->mm;
 203         unsigned int fixup;
 204         unsigned long g2;
 205         int from_user = !(regs->psr & PSR_PS);
 206         int fault, code;
 207         unsigned int flags = (FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
 208                               (write ? FAULT_FLAG_WRITE : 0));
 209
 210         if(text_fault)
 211                 address = regs->pc;
 212
 213         /*
 214          * We fault-in kernel-space virtual memory on-demand. The
 215          * 'reference' page table is init_mm.pgd.
 216          *
 217          * NOTE! We MUST NOT take any locks for this case. We may
 218          * be in an interrupt or a critical region, and should
 219          * only copy the information from the master page table,
 220          * nothing more.
 221          */
 222         code = SEGV_MAPERR;
 223         if (address >= TASK_SIZE)
 224                 goto vmalloc_fault;
 225
 226         /*
 227          * If we're in an interrupt or have no user
 228          * context, we must not take the fault..
 229          */
 230         if (in_atomic() || !mm)
 231                 goto no_context;
 232
 233         perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
 234
 235 retry:
 236         down_read(&mm->mmap_sem);
 237
 238         if(!from_user && address >= PAGE_OFFSET)
 239                 goto bad_area;
 240
 241         vma = find_vma(mm, address);
 242         if(!vma)
 243                 goto bad_area;
 244         if(vma->vm_start <= address)
 245                 goto good_area;
 246         if(!(vma->vm_flags & VM_GROWSDOWN))
 247                 goto bad_area;
 248         if(expand_stack(vma, address))
 249                 goto bad_area;
 250         /*
 251          * Ok, we have a good vm_area for this memory access, so
 252          * we can handle it..
 253          */
 254 good_area:
 255         code = SEGV_ACCERR;
 256         if(write) {
 257                 if(!(vma->vm_flags & VM_WRITE))
 258                         goto bad_area;
 259         } else {
 260                 /* Allow reads even for write-only mappings */
 261                 if(!(vma->vm_flags & (VM_READ | VM_EXEC)))
 262                         goto bad_area;
 263         }
 264
 265         /*
 266          * If for any reason at all we couldn't handle the fault,
 267          * make sure we exit gracefully rather than endlessly redo
 268          * the fault.
 269          */
 270         fault = handle_mm_fault(mm, vma, address, flags);
 271
 272         if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
 273                 return;
 274
 275         if (unlikely(fault & VM_FAULT_ERROR)) {
 276                 if (fault & VM_FAULT_OOM)
 277                         goto out_of_memory;
 278                 else if (fault & VM_FAULT_SIGBUS)
 279                         goto do_sigbus;
 280                 BUG();
 281         }
 282
 283         if (flags & FAULT_FLAG_ALLOW_RETRY) {
 284                 if (fault & VM_FAULT_MAJOR) {
 285                         current->maj_flt++;
 286                         perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ,
 287                                       1, regs, address);
 288                 } else {
 289                         current->min_flt++;
 290                         perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN,
 291                                       1, regs, address);
 292                 }
 293                 if (fault & VM_FAULT_RETRY) {
 294                         flags &= ~FAULT_FLAG_ALLOW_RETRY;
 295
 296                         /* No need to up_read(&mm->mmap_sem) as we would
 297                          * have already released it in __lock_page_or_retry
 298                          * in mm/filemap.c.
 299                          */
 300
 301                         goto retry;
 302                 }
 303         }
 304
 305         up_read(&mm->mmap_sem);
 306         return;
 307
 308         /*
 309          * Something tried to access memory that isn't in our memory map..
 310          * Fix it, but check if it's kernel or user first..
 311          */
 312 bad_area:
 313         up_read(&mm->mmap_sem);
 314
 315 bad_area_nosemaphore:
 316         /* User mode accesses just cause a SIGSEGV */
 317         if (from_user) {
 318                 do_fault_siginfo(code, SIGSEGV, regs, text_fault);
 319                 return;
 320         }
 321
 322         /* Is this in ex_table? */
 323 no_context:
 324         g2 = regs->u_regs[UREG_G2];
 325         if (!from_user) {
 326                 fixup = search_extables_range(regs->pc, &g2);
 327                 if (fixup > 10) { /* Values below are reserved for other things */
 328                         extern const unsigned __memset_start[];
 329                         extern const unsigned __memset_end[];
 330                         extern const unsigned __csum_partial_copy_start[];
 331                         extern const unsigned __csum_partial_copy_end[];
 332
 333 #ifdef DEBUG_EXCEPTIONS
 334                         printk("Exception: PC<%08lx> faddr<%08lx>\n", regs->pc, address);
 335                         printk("EX_TABLE: insn<%08lx> fixup<%08x> g2<%08lx>\n",
 336                                 regs->pc, fixup, g2);
 337 #endif
 338                         if ((regs->pc >= (unsigned long)__memset_start &&
 339                              regs->pc < (unsigned long)__memset_end) ||
 340                             (regs->pc >= (unsigned long)__csum_partial_copy_start &&
 341                              regs->pc < (unsigned long)__csum_partial_copy_end)) {
 342                                 regs->u_regs[UREG_I4] = address;
 343                                 regs->u_regs[UREG_I5] = regs->pc;
 344                         }
 345                         regs->u_regs[UREG_G2] = g2;
 346                         regs->pc = fixup;
 347                         regs->npc = regs->pc + 4;
 348                         return;
 349                 }
 350         }
 351
 352         unhandled_fault (address, tsk, regs);
 353         do_exit(SIGKILL);
 354
 355 /*
 356  * We ran out of memory, or some other thing happened to us that made
 357  * us unable to handle the page fault gracefully.
 358  */
 359 out_of_memory:
 360         up_read(&mm->mmap_sem);
 361         if (from_user) {
 362                 pagefault_out_of_memory();
 363                 return;
 364         }
 365         goto no_context;
 366
 367 do_sigbus:
 368         up_read(&mm->mmap_sem);
 369         do_fault_siginfo(BUS_ADRERR, SIGBUS, regs, text_fault);
 370         if (!from_user)
 371                 goto no_context;
 372
 373 vmalloc_fault:
 374         {
 375                 /*
 376                  * Synchronize this task's top level page-table
 377                  * with the 'reference' page table.
 378                  */
 379                 int offset = pgd_index(address);
 380                 pgd_t *pgd, *pgd_k;
 381                 pmd_t *pmd, *pmd_k;
 382
 383                 pgd = tsk->active_mm->pgd + offset;
 384                 pgd_k = init_mm.pgd + offset;
 385
 386                 if (!pgd_present(*pgd)) {
 387                         if (!pgd_present(*pgd_k))
 388                                 goto bad_area_nosemaphore;
 389                         pgd_val(*pgd) = pgd_val(*pgd_k);
 390                         return;
 391                 }
 392
 393                 pmd = pmd_offset(pgd, address);
 394                 pmd_k = pmd_offset(pgd_k, address);
 395
 396                 if (pmd_present(*pmd) || !pmd_present(*pmd_k))
 397                         goto bad_area_nosemaphore;
 398                 *pmd = *pmd_k;
 399                 return;
 400         }
 401 }
 402
 403 /* This always deals with user addresses. */
 404 static void force_user_fault(unsigned long address, int write)
 405 {
 406         struct vm_area_struct *vma;
 407         struct task_struct *tsk = current;
 408         struct mm_struct *mm = tsk->mm;
 409         int code;
 410
 411         code = SEGV_MAPERR;
 412
 413         down_read(&mm->mmap_sem);
 414         vma = find_vma(mm, address);
 415         if(!vma)
 416                 goto bad_area;
 417         if(vma->vm_start <= address)
 418                 goto good_area;
 419         if(!(vma->vm_flags & VM_GROWSDOWN))
 420                 goto bad_area;
 421         if(expand_stack(vma, address))
 422                 goto bad_area;
 423 good_area:
 424         code = SEGV_ACCERR;
 425         if(write) {
 426                 if(!(vma->vm_flags & VM_WRITE))
 427                         goto bad_area;
 428         } else {
 429                 if(!(vma->vm_flags & (VM_READ | VM_EXEC)))
 430                         goto bad_area;
 431         }
 432         switch (handle_mm_fault(mm, vma, address, write ? FAULT_FLAG_WRITE : 0)) {
 433         case VM_FAULT_SIGBUS:
 434         case VM_FAULT_OOM:
 435                 goto do_sigbus;
 436         }
 437         up_read(&mm->mmap_sem);
 438         return;
 439 bad_area:
 440         up_read(&mm->mmap_sem);
 441         __do_fault_siginfo(code, SIGSEGV, tsk->thread.kregs, address);
 442         return;
 443
 444 do_sigbus:
 445         up_read(&mm->mmap_sem);
 446         __do_fault_siginfo(BUS_ADRERR, SIGBUS, tsk->thread.kregs, address);
 447 }
 448
 449 static void check_stack_aligned(unsigned long sp)
 450 {
 451         if (sp & 0x7UL)
 452                 force_sig(SIGILL, current);
 453 }
 454
 455 void window_overflow_fault(void)
 456 {
 457         unsigned long sp;
 458
 459         sp = current_thread_info()->rwbuf_stkptrs[0];
 460         if(((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
 461                 force_user_fault(sp + 0x38, 1);
 462         force_user_fault(sp, 1);
 463
 464         check_stack_aligned(sp);
 465 }
 466
 467 void window_underflow_fault(unsigned long sp)
 468 {
 469         if(((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
 470                 force_user_fault(sp + 0x38, 0);
 471         force_user_fault(sp, 0);
 472
 473         check_stack_aligned(sp);
 474 }
 475
 476 void window_ret_fault(struct pt_regs *regs)
 477 {
 478         unsigned long sp;
 479
 480         sp = regs->u_regs[UREG_FP];
 481         if(((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
 482                 force_user_fault(sp + 0x38, 0);
 483         force_user_fault(sp, 0);
 484
 485         check_stack_aligned(sp);
 486 }