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
  27 #include <asm/system.h>
  28 #include <asm/uaccess.h>
  29 #include <asm/pgalloc.h>
  30 #include <asm/hardirq.h>
  31 #include <asm/cpu-regs.h>
  32 #include <asm/debugger.h>
  33 #include <asm/gdb-stub.h>
  34
  35 /*
  36  * Unlock any spinlocks which will prevent us from getting the
  37  * message out
  38  */
  39 void bust_spinlocks(int yes)
  40 {
  41         if (yes) {
  42                 oops_in_progress = 1;
  43         } else {
  44                 int loglevel_save = console_loglevel;
  45 #ifdef CONFIG_VT
  46                 unblank_screen();
  47 #endif
  48                 oops_in_progress = 0;
  49                 /*
  50                  * OK, the message is on the console.  Now we call printk()
  51                  * without oops_in_progress set so that printk will give klogd
  52                  * a poke.  Hold onto your hats...
  53                  */
  54                 console_loglevel = 15;  /* NMI oopser may have shut the console
  55                                          * up */
  56                 printk(" ");
  57                 console_loglevel = loglevel_save;
  58         }
  59 }
  60
  61 void do_BUG(const char *file, int line)
  62 {
  63         bust_spinlocks(1);
  64         printk(KERN_EMERG "------------[ cut here ]------------\n");
  65         printk(KERN_EMERG "kernel BUG at %s:%d!\n", file, line);
  66 }
  67
  68 #if 0
  69 static void print_pagetable_entries(pgd_t *pgdir, unsigned long address)
  70 {
  71         pgd_t *pgd;
  72         pmd_t *pmd;
  73         pte_t *pte;
  74
  75         pgd = pgdir + __pgd_offset(address);
  76         printk(KERN_DEBUG "pgd entry %p: %016Lx\n",
  77                pgd, (long long) pgd_val(*pgd));
  78
  79         if (!pgd_present(*pgd)) {
  80                 printk(KERN_DEBUG "... pgd not present!\n");
  81                 return;
  82         }
  83         pmd = pmd_offset(pgd, address);
  84         printk(KERN_DEBUG "pmd entry %p: %016Lx\n",
  85                pmd, (long long)pmd_val(*pmd));
  86
  87         if (!pmd_present(*pmd)) {
  88                 printk(KERN_DEBUG "... pmd not present!\n");
  89                 return;
  90         }
  91         pte = pte_offset(pmd, address);
  92         printk(KERN_DEBUG "pte entry %p: %016Lx\n",
  93                pte, (long long) pte_val(*pte));
  94
  95         if (!pte_present(*pte))
  96                 printk(KERN_DEBUG "... pte not present!\n");
  97 }
  98 #endif
  99
 100 /*
 101  * This routine handles page faults.  It determines the address,
 102  * and the problem, and then passes it off to one of the appropriate
 103  * routines.
 104  *
 105  * fault_code:
 106  * - LSW: either MMUFCR_IFC or MMUFCR_DFC as appropriate
 107  * - MSW: 0 if data access, 1 if instruction access
 108  * - bit 0: TLB miss flag
 109  * - bit 1: initial write
 110  * - bit 2: page invalid
 111  * - bit 3: protection violation
 112  * - bit 4: accessor (0=user 1=kernel)
 113  * - bit 5: 0=read 1=write
 114  * - bit 6-8: page protection spec
 115  * - bit 9: illegal address
 116  * - bit 16: 0=data 1=ins
 117  *
 118  */
 119 asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long fault_code,
 120                               unsigned long address)
 121 {
 122         struct vm_area_struct *vma;
 123         struct task_struct *tsk;
 124         struct mm_struct *mm;
 125         unsigned long page;
 126         siginfo_t info;
 127         int write, fault;
 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 (in_atomic() || !mm)
 172                 goto no_context;
 173
 174         down_read(&mm->mmap_sem);
 175
 176         vma = find_vma(mm, address);
 177         if (!vma)
 178                 goto bad_area;
 179         if (vma->vm_start <= address)
 180                 goto good_area;
 181         if (!(vma->vm_flags & VM_GROWSDOWN))
 182                 goto bad_area;
 183
 184         if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_USR) {
 185                 /* accessing the stack below the stack pointer is always a
 186                  * bug */
 187                 if ((address & PAGE_MASK) + 2 * PAGE_SIZE < regs->sp) {
 188 #if 0
 189                         printk(KERN_WARNING
 190                                "[%d] ### Access below stack @%lx (sp=%lx)\n",
 191                                current->pid, address, regs->sp);
 192                         printk(KERN_WARNING
 193                                "vma [%08x - %08x]\n",
 194                                vma->vm_start, vma->vm_end);
 195                         show_registers(regs);
 196                         printk(KERN_WARNING
 197                                "[%d] ### Code: [%08lx]"
 198                                " %02x %02x %02x %02x %02x %02x %02x %02x\n",
 199                                current->pid,
 200                                regs->pc,
 201                                ((u8 *) regs->pc)[0],
 202                                ((u8 *) regs->pc)[1],
 203                                ((u8 *) regs->pc)[2],
 204                                ((u8 *) regs->pc)[3],
 205                                ((u8 *) regs->pc)[4],
 206                                ((u8 *) regs->pc)[5],
 207                                ((u8 *) regs->pc)[6],
 208                                ((u8 *) regs->pc)[7]
 209                                );
 210 #endif
 211                         goto bad_area;
 212                 }
 213         }
 214
 215         if (expand_stack(vma, address))
 216                 goto bad_area;
 217
 218 /*
 219  * Ok, we have a good vm_area for this memory access, so
 220  * we can handle it..
 221  */
 222 good_area:
 223         info.si_code = SEGV_ACCERR;
 224         write = 0;
 225         switch (fault_code & (MMUFCR_xFC_PGINVAL|MMUFCR_xFC_TYPE)) {
 226         default:        /* 3: write, present */
 227         case MMUFCR_xFC_TYPE_WRITE:
 228 #ifdef TEST_VERIFY_AREA
 229                 if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_SR)
 230                         printk(KERN_DEBUG "WP fault at %08lx\n", regs->pc);
 231 #endif
 232                 /* write to absent page */
 233         case MMUFCR_xFC_PGINVAL | MMUFCR_xFC_TYPE_WRITE:
 234                 if (!(vma->vm_flags & VM_WRITE))
 235                         goto bad_area;
 236                 write++;
 237                 break;
 238
 239                 /* read from protected page */
 240         case MMUFCR_xFC_TYPE_READ:
 241                 goto bad_area;
 242
 243                 /* read from absent page present */
 244         case MMUFCR_xFC_PGINVAL | MMUFCR_xFC_TYPE_READ:
 245                 if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
 246                         goto bad_area;
 247                 break;
 248         }
 249
 250         /*
 251          * If for any reason at all we couldn't handle the fault,
 252          * make sure we exit gracefully rather than endlessly redo
 253          * the fault.
 254          */
 255         fault = handle_mm_fault(mm, vma, address, write ? FAULT_FLAG_WRITE : 0);
 256         if (unlikely(fault & VM_FAULT_ERROR)) {
 257                 if (fault & VM_FAULT_OOM)
 258                         goto out_of_memory;
 259                 else if (fault & VM_FAULT_SIGBUS)
 260                         goto do_sigbus;
 261                 BUG();
 262         }
 263         if (fault & VM_FAULT_MAJOR)
 264                 current->maj_flt++;
 265         else
 266                 current->min_flt++;
 267
 268         up_read(&mm->mmap_sem);
 269         return;
 270
 271 /*
 272  * Something tried to access memory that isn't in our memory map..
 273  * Fix it, but check if it's kernel or user first..
 274  */
 275 bad_area:
 276         up_read(&mm->mmap_sem);
 277
 278         /* User mode accesses just cause a SIGSEGV */
 279         if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_USR) {
 280                 info.si_signo = SIGSEGV;
 281                 info.si_errno = 0;
 282                 /* info.si_code has been set above */
 283                 info.si_addr = (void *)address;
 284                 force_sig_info(SIGSEGV, &info, tsk);
 285                 return;
 286         }
 287
 288 no_context:
 289         /* Are we prepared to handle this kernel fault?  */
 290         if (fixup_exception(regs))
 291                 return;
 292
 293 /*
 294  * Oops. The kernel tried to access some bad page. We'll have to
 295  * terminate things with extreme prejudice.
 296  */
 297
 298         bust_spinlocks(1);
 299
 300         if (address < PAGE_SIZE)
 301                 printk(KERN_ALERT
 302                        "Unable to handle kernel NULL pointer dereference");
 303         else
 304                 printk(KERN_ALERT
 305                        "Unable to handle kernel paging request");
 306         printk(" at virtual address %08lx\n", address);
 307         printk(" printing pc:\n");
 308         printk(KERN_ALERT "%08lx\n", regs->pc);
 309
 310         debugger_intercept(fault_code & 0x00010000 ? EXCEP_IAERROR : EXCEP_DAERROR,
 311                            SIGSEGV, SEGV_ACCERR, regs);
 312
 313         page = PTBR;
 314         page = ((unsigned long *) __va(page))[address >> 22];
 315         printk(KERN_ALERT "*pde = %08lx\n", page);
 316         if (page & 1) {
 317                 page &= PAGE_MASK;
 318                 address &= 0x003ff000;
 319                 page = ((unsigned long *) __va(page))[address >> PAGE_SHIFT];
 320                 printk(KERN_ALERT "*pte = %08lx\n", page);
 321         }
 322
 323         die("Oops", regs, fault_code);
 324         do_exit(SIGKILL);
 325
 326 /*
 327  * We ran out of memory, or some other thing happened to us that made
 328  * us unable to handle the page fault gracefully.
 329  */
 330 out_of_memory:
 331         up_read(&mm->mmap_sem);
 332         printk(KERN_ALERT "VM: killing process %s\n", tsk->comm);
 333         if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_USR)
 334                 do_exit(SIGKILL);
 335         goto no_context;
 336
 337 do_sigbus:
 338         up_read(&mm->mmap_sem);
 339
 340         /*
 341          * Send a sigbus, regardless of whether we were in kernel
 342          * or user mode.
 343          */
 344         info.si_signo = SIGBUS;
 345         info.si_errno = 0;
 346         info.si_code = BUS_ADRERR;
 347         info.si_addr = (void *)address;
 348         force_sig_info(SIGBUS, &info, tsk);
 349
 350         /* Kernel mode? Handle exceptions or die */
 351         if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_SR)
 352                 goto no_context;
 353         return;
 354
 355 vmalloc_fault:
 356         {
 357                 /*
 358                  * Synchronize this task's top level page-table
 359                  * with the 'reference' page table.
 360                  *
 361                  * Do _not_ use "tsk" here. We might be inside
 362                  * an interrupt in the middle of a task switch..
 363                  */
 364                 int index = pgd_index(address);
 365                 pgd_t *pgd, *pgd_k;
 366                 pud_t *pud, *pud_k;
 367                 pmd_t *pmd, *pmd_k;
 368                 pte_t *pte_k;
 369
 370                 pgd_k = init_mm.pgd + index;
 371
 372                 if (!pgd_present(*pgd_k))
 373                         goto no_context;
 374
 375                 pud_k = pud_offset(pgd_k, address);
 376                 if (!pud_present(*pud_k))
 377                         goto no_context;
 378
 379                 pmd_k = pmd_offset(pud_k, address);
 380                 if (!pmd_present(*pmd_k))
 381                         goto no_context;
 382
 383                 pgd = (pgd_t *) PTBR + index;
 384                 pud = pud_offset(pgd, address);
 385                 pmd = pmd_offset(pud, address);
 386                 set_pmd(pmd, *pmd_k);
 387
 388                 pte_k = pte_offset_kernel(pmd_k, address);
 389                 if (!pte_present(*pte_k))
 390                         goto no_context;
 391                 return;
 392         }
 393 }