linux/arch/parisc/mm/fault.c
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   1/* $Id: fault.c,v 1.5 2000/01/26 16:20:29 jsm Exp $
   2 *
   3 * This file is subject to the terms and conditions of the GNU General Public
   4 * License.  See the file "COPYING" in the main directory of this archive
   5 * for more details.
   6 *
   7 *
   8 * Copyright (C) 1995, 1996, 1997, 1998 by Ralf Baechle
   9 * Copyright 1999 SuSE GmbH (Philipp Rumpf, prumpf@tux.org)
  10 * Copyright 1999 Hewlett Packard Co.
  11 *
  12 */
  13
  14#include <linux/mm.h>
  15#include <linux/ptrace.h>
  16#include <linux/sched.h>
  17#include <linux/interrupt.h>
  18#include <linux/module.h>
  19
  20#include <asm/uaccess.h>
  21#include <asm/traps.h>
  22
  23#define PRINT_USER_FAULTS /* (turn this on if you want user faults to be */
  24                         /*  dumped to the console via printk)          */
  25
  26
  27/* Various important other fields */
  28#define bit22set(x)             (x & 0x00000200)
  29#define bits23_25set(x)         (x & 0x000001c0)
  30#define isGraphicsFlushRead(x)  ((x & 0xfc003fdf) == 0x04001a80)
  31                                /* extended opcode is 0x6a */
  32
  33#define BITSSET         0x1c0   /* for identifying LDCW */
  34
  35
  36DEFINE_PER_CPU(struct exception_data, exception_data);
  37
  38/*
  39 * parisc_acctyp(unsigned int inst) --
  40 *    Given a PA-RISC memory access instruction, determine if the
  41 *    the instruction would perform a memory read or memory write
  42 *    operation.
  43 *
  44 *    This function assumes that the given instruction is a memory access
  45 *    instruction (i.e. you should really only call it if you know that
  46 *    the instruction has generated some sort of a memory access fault).
  47 *
  48 * Returns:
  49 *   VM_READ  if read operation
  50 *   VM_WRITE if write operation
  51 *   VM_EXEC  if execute operation
  52 */
  53static unsigned long
  54parisc_acctyp(unsigned long code, unsigned int inst)
  55{
  56        if (code == 6 || code == 16)
  57            return VM_EXEC;
  58
  59        switch (inst & 0xf0000000) {
  60        case 0x40000000: /* load */
  61        case 0x50000000: /* new load */
  62                return VM_READ;
  63
  64        case 0x60000000: /* store */
  65        case 0x70000000: /* new store */
  66                return VM_WRITE;
  67
  68        case 0x20000000: /* coproc */
  69        case 0x30000000: /* coproc2 */
  70                if (bit22set(inst))
  71                        return VM_WRITE;
  72
  73        case 0x0: /* indexed/memory management */
  74                if (bit22set(inst)) {
  75                        /*
  76                         * Check for the 'Graphics Flush Read' instruction.
  77                         * It resembles an FDC instruction, except for bits
  78                         * 20 and 21. Any combination other than zero will
  79                         * utilize the block mover functionality on some
  80                         * older PA-RISC platforms.  The case where a block
  81                         * move is performed from VM to graphics IO space
  82                         * should be treated as a READ.
  83                         *
  84                         * The significance of bits 20,21 in the FDC
  85                         * instruction is:
  86                         *
  87                         *   00  Flush data cache (normal instruction behavior)
  88                         *   01  Graphics flush write  (IO space -> VM)
  89                         *   10  Graphics flush read   (VM -> IO space)
  90                         *   11  Graphics flush read/write (VM <-> IO space)
  91                         */
  92                        if (isGraphicsFlushRead(inst))
  93                                return VM_READ;
  94                        return VM_WRITE;
  95                } else {
  96                        /*
  97                         * Check for LDCWX and LDCWS (semaphore instructions).
  98                         * If bits 23 through 25 are all 1's it is one of
  99                         * the above two instructions and is a write.
 100                         *
 101                         * Note: With the limited bits we are looking at,
 102                         * this will also catch PROBEW and PROBEWI. However,
 103                         * these should never get in here because they don't
 104                         * generate exceptions of the type:
 105                         *   Data TLB miss fault/data page fault
 106                         *   Data memory protection trap
 107                         */
 108                        if (bits23_25set(inst) == BITSSET)
 109                                return VM_WRITE;
 110                }
 111                return VM_READ; /* Default */
 112        }
 113        return VM_READ; /* Default */
 114}
 115
 116#undef bit22set
 117#undef bits23_25set
 118#undef isGraphicsFlushRead
 119#undef BITSSET
 120
 121
 122#if 0
 123/* This is the treewalk to find a vma which is the highest that has
 124 * a start < addr.  We're using find_vma_prev instead right now, but
 125 * we might want to use this at some point in the future.  Probably
 126 * not, but I want it committed to CVS so I don't lose it :-)
 127 */
 128                        while (tree != vm_avl_empty) {
 129                                if (tree->vm_start > addr) {
 130                                        tree = tree->vm_avl_left;
 131                                } else {
 132                                        prev = tree;
 133                                        if (prev->vm_next == NULL)
 134                                                break;
 135                                        if (prev->vm_next->vm_start > addr)
 136                                                break;
 137                                        tree = tree->vm_avl_right;
 138                                }
 139                        }
 140#endif
 141
 142void do_page_fault(struct pt_regs *regs, unsigned long code,
 143                              unsigned long address)
 144{
 145        struct vm_area_struct *vma, *prev_vma;
 146        struct task_struct *tsk = current;
 147        struct mm_struct *mm = tsk->mm;
 148        const struct exception_table_entry *fix;
 149        unsigned long acc_type;
 150        int fault;
 151
 152        if (in_atomic() || !mm)
 153                goto no_context;
 154
 155        down_read(&mm->mmap_sem);
 156        vma = find_vma_prev(mm, address, &prev_vma);
 157        if (!vma || address < vma->vm_start)
 158                goto check_expansion;
 159/*
 160 * Ok, we have a good vm_area for this memory access. We still need to
 161 * check the access permissions.
 162 */
 163
 164good_area:
 165
 166        acc_type = parisc_acctyp(code,regs->iir);
 167
 168        if ((vma->vm_flags & acc_type) != acc_type)
 169                goto bad_area;
 170
 171        /*
 172         * If for any reason at all we couldn't handle the fault, make
 173         * sure we exit gracefully rather than endlessly redo the
 174         * fault.
 175         */
 176
 177        fault = handle_mm_fault(mm, vma, address, (acc_type & VM_WRITE) != 0);
 178        if (unlikely(fault & VM_FAULT_ERROR)) {
 179                /*
 180                 * We hit a shared mapping outside of the file, or some
 181                 * other thing happened to us that made us unable to
 182                 * handle the page fault gracefully.
 183                 */
 184                if (fault & VM_FAULT_OOM)
 185                        goto out_of_memory;
 186                else if (fault & VM_FAULT_SIGBUS)
 187                        goto bad_area;
 188                BUG();
 189        }
 190        if (fault & VM_FAULT_MAJOR)
 191                current->maj_flt++;
 192        else
 193                current->min_flt++;
 194        up_read(&mm->mmap_sem);
 195        return;
 196
 197check_expansion:
 198        vma = prev_vma;
 199        if (vma && (expand_stack(vma, address) == 0))
 200                goto good_area;
 201
 202/*
 203 * Something tried to access memory that isn't in our memory map..
 204 */
 205bad_area:
 206        up_read(&mm->mmap_sem);
 207
 208        if (user_mode(regs)) {
 209                struct siginfo si;
 210
 211#ifdef PRINT_USER_FAULTS
 212                printk(KERN_DEBUG "\n");
 213                printk(KERN_DEBUG "do_page_fault() pid=%d command='%s' type=%lu address=0x%08lx\n",
 214                    task_pid_nr(tsk), tsk->comm, code, address);
 215                if (vma) {
 216                        printk(KERN_DEBUG "vm_start = 0x%08lx, vm_end = 0x%08lx\n",
 217                                        vma->vm_start, vma->vm_end);
 218                }
 219                show_regs(regs);
 220#endif
 221                /* FIXME: actually we need to get the signo and code correct */
 222                si.si_signo = SIGSEGV;
 223                si.si_errno = 0;
 224                si.si_code = SEGV_MAPERR;
 225                si.si_addr = (void __user *) address;
 226                force_sig_info(SIGSEGV, &si, current);
 227                return;
 228        }
 229
 230no_context:
 231
 232        if (!user_mode(regs)) {
 233                fix = search_exception_tables(regs->iaoq[0]);
 234
 235                if (fix) {
 236                        struct exception_data *d;
 237
 238                        d = &__get_cpu_var(exception_data);
 239                        d->fault_ip = regs->iaoq[0];
 240                        d->fault_space = regs->isr;
 241                        d->fault_addr = regs->ior;
 242
 243                        regs->iaoq[0] = ((fix->fixup) & ~3);
 244
 245                        /*
 246                         * NOTE: In some cases the faulting instruction
 247                         * may be in the delay slot of a branch. We
 248                         * don't want to take the branch, so we don't
 249                         * increment iaoq[1], instead we set it to be
 250                         * iaoq[0]+4, and clear the B bit in the PSW
 251                         */
 252
 253                        regs->iaoq[1] = regs->iaoq[0] + 4;
 254                        regs->gr[0] &= ~PSW_B; /* IPSW in gr[0] */
 255
 256                        return;
 257                }
 258        }
 259
 260        parisc_terminate("Bad Address (null pointer deref?)", regs, code, address);
 261
 262  out_of_memory:
 263        up_read(&mm->mmap_sem);
 264        printk(KERN_CRIT "VM: killing process %s\n", current->comm);
 265        if (user_mode(regs))
 266                do_group_exit(SIGKILL);
 267        goto no_context;
 268}
 269
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