LXR linux/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 */
  39void 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
  61void 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
  69static 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 */
 119asmlinkage 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 */
 222good_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 */
 275bad_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
 288no_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 */
 330out_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
 337do_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
 355vmalloc_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}
 394