LXR linux/arch/parisc/mm/fault.c

   1/*
   2 * This file is subject to the terms and conditions of the GNU General Public
   3 * License.  See the file "COPYING" in the main directory of this archive
   4 * for more details.
   5 *
   6 *
   7 * Copyright (C) 1995, 1996, 1997, 1998 by Ralf Baechle
   8 * Copyright 1999 SuSE GmbH (Philipp Rumpf, prumpf@tux.org)
   9 * Copyright 1999 Hewlett Packard Co.
  10 *
  11 */
  12
  13#include <linux/mm.h>
  14#include <linux/ptrace.h>
  15#include <linux/sched.h>
  16#include <linux/interrupt.h>
  17#include <linux/module.h>
  18
  19#include <asm/uaccess.h>
  20#include <asm/traps.h>
  21
  22#define PRINT_USER_FAULTS /* (turn this on if you want user faults to be */
  23                         /*  dumped to the console via printk)          */
  24
  25
  26/* Various important other fields */
  27#define bit22set(x)             (x & 0x00000200)
  28#define bits23_25set(x)         (x & 0x000001c0)
  29#define isGraphicsFlushRead(x)  ((x & 0xfc003fdf) == 0x04001a80)
  30                                /* extended opcode is 0x6a */
  31
  32#define BITSSET         0x1c0   /* for identifying LDCW */
  33
  34
  35DEFINE_PER_CPU(struct exception_data, exception_data);
  36
  37/*
  38 * parisc_acctyp(unsigned int inst) --
  39 *    Given a PA-RISC memory access instruction, determine if the
  40 *    the instruction would perform a memory read or memory write
  41 *    operation.
  42 *
  43 *    This function assumes that the given instruction is a memory access
  44 *    instruction (i.e. you should really only call it if you know that
  45 *    the instruction has generated some sort of a memory access fault).
  46 *
  47 * Returns:
  48 *   VM_READ  if read operation
  49 *   VM_WRITE if write operation
  50 *   VM_EXEC  if execute operation
  51 */
  52static unsigned long
  53parisc_acctyp(unsigned long code, unsigned int inst)
  54{
  55        if (code == 6 || code == 16)
  56            return VM_EXEC;
  57
  58        switch (inst & 0xf0000000) {
  59        case 0x40000000: /* load */
  60        case 0x50000000: /* new load */
  61                return VM_READ;
  62
  63        case 0x60000000: /* store */
  64        case 0x70000000: /* new store */
  65                return VM_WRITE;
  66
  67        case 0x20000000: /* coproc */
  68        case 0x30000000: /* coproc2 */
  69                if (bit22set(inst))
  70                        return VM_WRITE;
  71
  72        case 0x0: /* indexed/memory management */
  73                if (bit22set(inst)) {
  74                        /*
  75                         * Check for the 'Graphics Flush Read' instruction.
  76                         * It resembles an FDC instruction, except for bits
  77                         * 20 and 21. Any combination other than zero will
  78                         * utilize the block mover functionality on some
  79                         * older PA-RISC platforms.  The case where a block
  80                         * move is performed from VM to graphics IO space
  81                         * should be treated as a READ.
  82                         *
  83                         * The significance of bits 20,21 in the FDC
  84                         * instruction is:
  85                         *
  86                         *   00  Flush data cache (normal instruction behavior)
  87                         *   01  Graphics flush write  (IO space -> VM)
  88                         *   10  Graphics flush read   (VM -> IO space)
  89                         *   11  Graphics flush read/write (VM <-> IO space)
  90                         */
  91                        if (isGraphicsFlushRead(inst))
  92                                return VM_READ;
  93                        return VM_WRITE;
  94                } else {
  95                        /*
  96                         * Check for LDCWX and LDCWS (semaphore instructions).
  97                         * If bits 23 through 25 are all 1's it is one of
  98                         * the above two instructions and is a write.
  99                         *
 100                         * Note: With the limited bits we are looking at,
 101                         * this will also catch PROBEW and PROBEWI. However,
 102                         * these should never get in here because they don't
 103                         * generate exceptions of the type:
 104                         *   Data TLB miss fault/data page fault
 105                         *   Data memory protection trap
 106                         */
 107                        if (bits23_25set(inst) == BITSSET)
 108                                return VM_WRITE;
 109                }
 110                return VM_READ; /* Default */
 111        }
 112        return VM_READ; /* Default */
 113}
 114
 115#undef bit22set
 116#undef bits23_25set
 117#undef isGraphicsFlushRead
 118#undef BITSSET
 119
 120
 121#if 0
 122/* This is the treewalk to find a vma which is the highest that has
 123 * a start < addr.  We're using find_vma_prev instead right now, but
 124 * we might want to use this at some point in the future.  Probably
 125 * not, but I want it committed to CVS so I don't lose it :-)
 126 */
 127                        while (tree != vm_avl_empty) {
 128                                if (tree->vm_start > addr) {
 129                                        tree = tree->vm_avl_left;
 130                                } else {
 131                                        prev = tree;
 132                                        if (prev->vm_next == NULL)
 133                                                break;
 134                                        if (prev->vm_next->vm_start > addr)
 135                                                break;
 136                                        tree = tree->vm_avl_right;
 137                                }
 138                        }
 139#endif
 140
 141int fixup_exception(struct pt_regs *regs)
 142{
 143        const struct exception_table_entry *fix;
 144
 145        fix = search_exception_tables(regs->iaoq[0]);
 146        if (fix) {
 147                struct exception_data *d;
 148                d = &__get_cpu_var(exception_data);
 149                d->fault_ip = regs->iaoq[0];
 150                d->fault_space = regs->isr;
 151                d->fault_addr = regs->ior;
 152
 153                regs->iaoq[0] = ((fix->fixup) & ~3);
 154                /*
 155                 * NOTE: In some cases the faulting instruction
 156                 * may be in the delay slot of a branch. We
 157                 * don't want to take the branch, so we don't
 158                 * increment iaoq[1], instead we set it to be
 159                 * iaoq[0]+4, and clear the B bit in the PSW
 160                 */
 161                regs->iaoq[1] = regs->iaoq[0] + 4;
 162                regs->gr[0] &= ~PSW_B; /* IPSW in gr[0] */
 163
 164                return 1;
 165        }
 166
 167        return 0;
 168}
 169
 170void do_page_fault(struct pt_regs *regs, unsigned long code,
 171                              unsigned long address)
 172{
 173        struct vm_area_struct *vma, *prev_vma;
 174        struct task_struct *tsk = current;
 175        struct mm_struct *mm = tsk->mm;
 176        unsigned long acc_type;
 177        int fault;
 178        unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
 179
 180        if (in_atomic() || !mm)
 181                goto no_context;
 182
 183retry:
 184        down_read(&mm->mmap_sem);
 185        vma = find_vma_prev(mm, address, &prev_vma);
 186        if (!vma || address < vma->vm_start)
 187                goto check_expansion;
 188/*
 189 * Ok, we have a good vm_area for this memory access. We still need to
 190 * check the access permissions.
 191 */
 192
 193good_area:
 194
 195        acc_type = parisc_acctyp(code,regs->iir);
 196
 197        if ((vma->vm_flags & acc_type) != acc_type)
 198                goto bad_area;
 199
 200        /*
 201         * If for any reason at all we couldn't handle the fault, make
 202         * sure we exit gracefully rather than endlessly redo the
 203         * fault.
 204         */
 205
 206        fault = handle_mm_fault(mm, vma, address,
 207                        flags | ((acc_type & VM_WRITE) ? FAULT_FLAG_WRITE : 0));
 208
 209        if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
 210                return;
 211
 212        if (unlikely(fault & VM_FAULT_ERROR)) {
 213                /*
 214                 * We hit a shared mapping outside of the file, or some
 215                 * other thing happened to us that made us unable to
 216                 * handle the page fault gracefully.
 217                 */
 218                if (fault & VM_FAULT_OOM)
 219                        goto out_of_memory;
 220                else if (fault & VM_FAULT_SIGBUS)
 221                        goto bad_area;
 222                BUG();
 223        }
 224        if (flags & FAULT_FLAG_ALLOW_RETRY) {
 225                if (fault & VM_FAULT_MAJOR)
 226                        current->maj_flt++;
 227                else
 228                        current->min_flt++;
 229                if (fault & VM_FAULT_RETRY) {
 230                        flags &= ~FAULT_FLAG_ALLOW_RETRY;
 231
 232                        /*
 233                         * No need to up_read(&mm->mmap_sem) as we would
 234                         * have already released it in __lock_page_or_retry
 235                         * in mm/filemap.c.
 236                         */
 237
 238                        goto retry;
 239                }
 240        }
 241        up_read(&mm->mmap_sem);
 242        return;
 243
 244check_expansion:
 245        vma = prev_vma;
 246        if (vma && (expand_stack(vma, address) == 0))
 247                goto good_area;
 248
 249/*
 250 * Something tried to access memory that isn't in our memory map..
 251 */
 252bad_area:
 253        up_read(&mm->mmap_sem);
 254
 255        if (user_mode(regs)) {
 256                struct siginfo si;
 257
 258#ifdef PRINT_USER_FAULTS
 259                printk(KERN_DEBUG "\n");
 260                printk(KERN_DEBUG "do_page_fault() pid=%d command='%s' type=%lu address=0x%08lx\n",
 261                    task_pid_nr(tsk), tsk->comm, code, address);
 262                if (vma) {
 263                        printk(KERN_DEBUG "vm_start = 0x%08lx, vm_end = 0x%08lx\n",
 264                                        vma->vm_start, vma->vm_end);
 265                }
 266                show_regs(regs);
 267#endif
 268                /* FIXME: actually we need to get the signo and code correct */
 269                si.si_signo = SIGSEGV;
 270                si.si_errno = 0;
 271                si.si_code = SEGV_MAPERR;
 272                si.si_addr = (void __user *) address;
 273                force_sig_info(SIGSEGV, &si, current);
 274                return;
 275        }
 276
 277no_context:
 278
 279        if (!user_mode(regs) && fixup_exception(regs)) {
 280                return;
 281        }
 282
 283        parisc_terminate("Bad Address (null pointer deref?)", regs, code, address);
 284
 285  out_of_memory:
 286        up_read(&mm->mmap_sem);
 287        if (!user_mode(regs))
 288                goto no_context;
 289        pagefault_out_of_memory();
 290}
 291