arch/mn10300/mm/fault.c

   1 /* MN10300 MMU Fault handler
   2  *
   3  * Copyright (C) 2007 Matsushita Electric Industrial Co., Ltd.
   4  * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
   5  * Modified by David Howells (dhowells@redhat.com)
   6  *
   7  * This program is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU General Public Licence
   9  * as published by the Free Software Foundation; either version
  10  * 2 of the Licence, or (at your option) any later version.
  11  */
  12
  13 #include <linux/signal.h>
  14 #include <linux/sched.h>
  15 #include <linux/kernel.h>
  16 #include <linux/errno.h>
  17 #include <linux/string.h>
  18 #include <linux/types.h>
  19 #include <linux/ptrace.h>
  20 #include <linux/mman.h>
  21 #include <linux/mm.h>
  22 #include <linux/smp.h>
  23 #include <linux/interrupt.h>
  24 #include <linux/init.h>
  25 #include <linux/vt_kern.h>              /* For unblank_screen() */
  26 #include <linux/uaccess.h>
  27
  28 #include <asm/pgalloc.h>
  29 #include <asm/hardirq.h>
  30 #include <asm/cpu-regs.h>
  31 #include <asm/debugger.h>
  32 #include <asm/gdb-stub.h>
  33
  34 /*
  35  * Unlock any spinlocks which will prevent us from getting the
  36  * message out
  37  */
  38 void bust_spinlocks(int yes)
  39 {
  40         if (yes) {
  41                 oops_in_progress = 1;
  42         } else {
  43                 int loglevel_save = console_loglevel;
  44 #ifdef CONFIG_VT
  45                 unblank_screen();
  46 #endif
  47                 oops_in_progress = 0;
  48                 /*
  49                  * OK, the message is on the console.  Now we call printk()
  50                  * without oops_in_progress set so that printk will give klogd
  51                  * a poke.  Hold onto your hats...
  52                  */
  53                 console_loglevel = 15;  /* NMI oopser may have shut the console
  54                                          * up */
  55                 printk(" ");
  56                 console_loglevel = loglevel_save;
  57         }
  58 }
  59
  60 void do_BUG(const char *file, int line)
  61 {
  62         bust_spinlocks(1);
  63         printk(KERN_EMERG "------------[ cut here ]------------\n");
  64         printk(KERN_EMERG "kernel BUG at %s:%d!\n", file, line);
  65 }
  66
  67 #if 0
  68 static void print_pagetable_entries(pgd_t *pgdir, unsigned long address)
  69 {
  70         pgd_t *pgd;
  71         pmd_t *pmd;
  72         pte_t *pte;
  73
  74         pgd = pgdir + __pgd_offset(address);
  75         printk(KERN_DEBUG "pgd entry %p: %016Lx\n",
  76                pgd, (long long) pgd_val(*pgd));
  77
  78         if (!pgd_present(*pgd)) {
  79                 printk(KERN_DEBUG "... pgd not present!\n");
  80                 return;
  81         }
  82         pmd = pmd_offset(pgd, address);
  83         printk(KERN_DEBUG "pmd entry %p: %016Lx\n",
  84                pmd, (long long)pmd_val(*pmd));
  85
  86         if (!pmd_present(*pmd)) {
  87                 printk(KERN_DEBUG "... pmd not present!\n");
  88                 return;
  89         }
  90         pte = pte_offset(pmd, address);
  91         printk(KERN_DEBUG "pte entry %p: %016Lx\n",
  92                pte, (long long) pte_val(*pte));
  93
  94         if (!pte_present(*pte))
  95                 printk(KERN_DEBUG "... pte not present!\n");
  96 }
  97 #endif
  98
  99 /*
 100  * This routine handles page faults.  It determines the address,
 101  * and the problem, and then passes it off to one of the appropriate
 102  * routines.
 103  *
 104  * fault_code:
 105  * - LSW: either MMUFCR_IFC or MMUFCR_DFC as appropriate
 106  * - MSW: 0 if data access, 1 if instruction access
 107  * - bit 0: TLB miss flag
 108  * - bit 1: initial write
 109  * - bit 2: page invalid
 110  * - bit 3: protection violation
 111  * - bit 4: accessor (0=user 1=kernel)
 112  * - bit 5: 0=read 1=write
 113  * - bit 6-8: page protection spec
 114  * - bit 9: illegal address
 115  * - bit 16: 0=data 1=ins
 116  *
 117  */
 118 asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long fault_code,
 119                               unsigned long address)
 120 {
 121         struct vm_area_struct *vma;
 122         struct task_struct *tsk;
 123         struct mm_struct *mm;
 124         unsigned long page;
 125         siginfo_t info;
 126         int fault;
 127         unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
 128
 129 #ifdef CONFIG_GDBSTUB
 130         /* handle GDB stub causing a fault */
 131         if (gdbstub_busy) {
 132                 gdbstub_exception(regs, TBR & TBR_INT_CODE);
 133                 return;
 134         }
 135 #endif
 136
 137 #if 0
 138         printk(KERN_DEBUG "--- do_page_fault(%p,%s:%04lx,%08lx)\n",
 139                regs,
 140                fault_code & 0x10000 ? "ins" : "data",
 141                fault_code & 0xffff, address);
 142 #endif
 143
 144         tsk = current;
 145
 146         /*
 147          * We fault-in kernel-space virtual memory on-demand. The
 148          * 'reference' page table is init_mm.pgd.
 149          *
 150          * NOTE! We MUST NOT take any locks for this case. We may
 151          * be in an interrupt or a critical region, and should
 152          * only copy the information from the master page table,
 153          * nothing more.
 154          *
 155          * This verifies that the fault happens in kernel space
 156          * and that the fault was a page not present (invalid) error
 157          */
 158         if (address >= VMALLOC_START && address < VMALLOC_END &&
 159             (fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_SR &&
 160             (fault_code & MMUFCR_xFC_PGINVAL) == MMUFCR_xFC_PGINVAL
 161             )
 162                 goto vmalloc_fault;
 163
 164         mm = tsk->mm;
 165         info.si_code = SEGV_MAPERR;
 166
 167         /*
 168          * If we're in an interrupt or have no user
 169          * context, we must not take the fault..
 170          */
 171         if (faulthandler_disabled() || !mm)
 172                 goto no_context;
 173
 174         if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_USR)
 175                 flags |= FAULT_FLAG_USER;
 176 retry:
 177         down_read(&mm->mmap_sem);
 178
 179         vma = find_vma(mm, address);
 180         if (!vma)
 181                 goto bad_area;
 182         if (vma->vm_start <= address)
 183                 goto good_area;
 184         if (!(vma->vm_flags & VM_GROWSDOWN))
 185                 goto bad_area;
 186
 187         if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_USR) {
 188                 /* accessing the stack below the stack pointer is always a
 189                  * bug */
 190                 if ((address & PAGE_MASK) + 2 * PAGE_SIZE < regs->sp) {
 191 #if 0
 192                         printk(KERN_WARNING
 193                                "[%d] ### Access below stack @%lx (sp=%lx)\n",
 194                                current->pid, address, regs->sp);
 195                         printk(KERN_WARNING
 196                                "vma [%08x - %08x]\n",
 197                                vma->vm_start, vma->vm_end);
 198                         show_registers(regs);
 199                         printk(KERN_WARNING
 200                                "[%d] ### Code: [%08lx]"
 201                                " %02x %02x %02x %02x %02x %02x %02x %02x\n",
 202                                current->pid,
 203                                regs->pc,
 204                                ((u8 *) regs->pc)[0],
 205                                ((u8 *) regs->pc)[1],
 206                                ((u8 *) regs->pc)[2],
 207                                ((u8 *) regs->pc)[3],
 208                                ((u8 *) regs->pc)[4],
 209                                ((u8 *) regs->pc)[5],
 210                                ((u8 *) regs->pc)[6],
 211                                ((u8 *) regs->pc)[7]
 212                                );
 213 #endif
 214                         goto bad_area;
 215                 }
 216         }
 217
 218         if (expand_stack(vma, address))
 219                 goto bad_area;
 220
 221 /*
 222  * Ok, we have a good vm_area for this memory access, so
 223  * we can handle it..
 224  */
 225 good_area:
 226         info.si_code = SEGV_ACCERR;
 227         switch (fault_code & (MMUFCR_xFC_PGINVAL|MMUFCR_xFC_TYPE)) {
 228         default:        /* 3: write, present */
 229         case MMUFCR_xFC_TYPE_WRITE:
 230 #ifdef TEST_VERIFY_AREA
 231                 if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_SR)
 232                         printk(KERN_DEBUG "WP fault at %08lx\n", regs->pc);
 233 #endif
 234                 /* write to absent page */
 235         case MMUFCR_xFC_PGINVAL | MMUFCR_xFC_TYPE_WRITE:
 236                 if (!(vma->vm_flags & VM_WRITE))
 237                         goto bad_area;
 238                 flags |= FAULT_FLAG_WRITE;
 239                 break;
 240
 241                 /* read from protected page */
 242         case MMUFCR_xFC_TYPE_READ:
 243                 goto bad_area;
 244
 245                 /* read from absent page present */
 246         case MMUFCR_xFC_PGINVAL | MMUFCR_xFC_TYPE_READ:
 247                 if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
 248                         goto bad_area;
 249                 break;
 250         }
 251
 252         /*
 253          * If for any reason at all we couldn't handle the fault,
 254          * make sure we exit gracefully rather than endlessly redo
 255          * the fault.
 256          */
 257         fault = handle_mm_fault(vma, address, flags);
 258
 259         if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
 260                 return;
 261
 262         if (unlikely(fault & VM_FAULT_ERROR)) {
 263                 if (fault & VM_FAULT_OOM)
 264                         goto out_of_memory;
 265                 else if (fault & VM_FAULT_SIGSEGV)
 266                         goto bad_area;
 267                 else if (fault & VM_FAULT_SIGBUS)
 268                         goto do_sigbus;
 269                 BUG();
 270         }
 271         if (flags & FAULT_FLAG_ALLOW_RETRY) {
 272                 if (fault & VM_FAULT_MAJOR)
 273                         current->maj_flt++;
 274                 else
 275                         current->min_flt++;
 276                 if (fault & VM_FAULT_RETRY) {
 277                         flags &= ~FAULT_FLAG_ALLOW_RETRY;
 278
 279                          /* No need to up_read(&mm->mmap_sem) as we would
 280                          * have already released it in __lock_page_or_retry
 281                          * in mm/filemap.c.
 282                          */
 283
 284                         goto retry;
 285                 }
 286         }
 287
 288         up_read(&mm->mmap_sem);
 289         return;
 290
 291 /*
 292  * Something tried to access memory that isn't in our memory map..
 293  * Fix it, but check if it's kernel or user first..
 294  */
 295 bad_area:
 296         up_read(&mm->mmap_sem);
 297
 298         /* User mode accesses just cause a SIGSEGV */
 299         if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_USR) {
 300                 info.si_signo = SIGSEGV;
 301                 info.si_errno = 0;
 302                 /* info.si_code has been set above */
 303                 info.si_addr = (void *)address;
 304                 force_sig_info(SIGSEGV, &info, tsk);
 305                 return;
 306         }
 307
 308 no_context:
 309         /* Are we prepared to handle this kernel fault?  */
 310         if (fixup_exception(regs))
 311                 return;
 312
 313 /*
 314  * Oops. The kernel tried to access some bad page. We'll have to
 315  * terminate things with extreme prejudice.
 316  */
 317
 318         bust_spinlocks(1);
 319
 320         if (address < PAGE_SIZE)
 321                 printk(KERN_ALERT
 322                        "Unable to handle kernel NULL pointer dereference");
 323         else
 324                 printk(KERN_ALERT
 325                        "Unable to handle kernel paging request");
 326         printk(" at virtual address %08lx\n", address);
 327         printk(" printing pc:\n");
 328         printk(KERN_ALERT "%08lx\n", regs->pc);
 329
 330         debugger_intercept(fault_code & 0x00010000 ? EXCEP_IAERROR : EXCEP_DAERROR,
 331                            SIGSEGV, SEGV_ACCERR, regs);
 332
 333         page = PTBR;
 334         page = ((unsigned long *) __va(page))[address >> 22];
 335         printk(KERN_ALERT "*pde = %08lx\n", page);
 336         if (page & 1) {
 337                 page &= PAGE_MASK;
 338                 address &= 0x003ff000;
 339                 page = ((unsigned long *) __va(page))[address >> PAGE_SHIFT];
 340                 printk(KERN_ALERT "*pte = %08lx\n", page);
 341         }
 342
 343         die("Oops", regs, fault_code);
 344         do_exit(SIGKILL);
 345
 346 /*
 347  * We ran out of memory, or some other thing happened to us that made
 348  * us unable to handle the page fault gracefully.
 349  */
 350 out_of_memory:
 351         up_read(&mm->mmap_sem);
 352         if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_USR) {
 353                 pagefault_out_of_memory();
 354                 return;
 355         }
 356         goto no_context;
 357
 358 do_sigbus:
 359         up_read(&mm->mmap_sem);
 360
 361         /*
 362          * Send a sigbus, regardless of whether we were in kernel
 363          * or user mode.
 364          */
 365         info.si_signo = SIGBUS;
 366         info.si_errno = 0;
 367         info.si_code = BUS_ADRERR;
 368         info.si_addr = (void *)address;
 369         force_sig_info(SIGBUS, &info, tsk);
 370
 371         /* Kernel mode? Handle exceptions or die */
 372         if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_SR)
 373                 goto no_context;
 374         return;
 375
 376 vmalloc_fault:
 377         {
 378                 /*
 379                  * Synchronize this task's top level page-table
 380                  * with the 'reference' page table.
 381                  *
 382                  * Do _not_ use "tsk" here. We might be inside
 383                  * an interrupt in the middle of a task switch..
 384                  */
 385                 int index = pgd_index(address);
 386                 pgd_t *pgd, *pgd_k;
 387                 pud_t *pud, *pud_k;
 388                 pmd_t *pmd, *pmd_k;
 389                 pte_t *pte_k;
 390
 391                 pgd_k = init_mm.pgd + index;
 392
 393                 if (!pgd_present(*pgd_k))
 394                         goto no_context;
 395
 396                 pud_k = pud_offset(pgd_k, address);
 397                 if (!pud_present(*pud_k))
 398                         goto no_context;
 399
 400                 pmd_k = pmd_offset(pud_k, address);
 401                 if (!pmd_present(*pmd_k))
 402                         goto no_context;
 403
 404                 pgd = (pgd_t *) PTBR + index;
 405                 pud = pud_offset(pgd, address);
 406                 pmd = pmd_offset(pud, address);
 407                 set_pmd(pmd, *pmd_k);
 408
 409                 pte_k = pte_offset_kernel(pmd_k, address);
 410                 if (!pte_present(*pte_k))
 411                         goto no_context;
 412                 return;
 413         }
 414 }