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   1 /* $Id: fault.c,v 1.14 2004/01/13 05:52:11 kkojima Exp $
   2  *
   3  *  linux/arch/sh/mm/fault.c
   4  *  Copyright (C) 1999  Niibe Yutaka
   5  *  Copyright (C) 2003  Paul Mundt
   6  *
   7  *  Based on linux/arch/i386/mm/fault.c:
   8  *   Copyright (C) 1995  Linus Torvalds
   9  */
  10
  11 #include <linux/signal.h>
  12 #include <linux/sched.h>
  13 #include <linux/kernel.h>
  14 #include <linux/errno.h>
  15 #include <linux/string.h>
  16 #include <linux/types.h>
  17 #include <linux/ptrace.h>
  18 #include <linux/mman.h>
  19 #include <linux/mm.h>
  20 #include <linux/smp.h>
  21 #include <linux/smp_lock.h>
  22 #include <linux/interrupt.h>
  23 #include <linux/module.h>
  24
  25 #include <asm/system.h>
  26 #include <asm/io.h>
  27 #include <asm/uaccess.h>
  28 #include <asm/pgalloc.h>
  29 #include <asm/mmu_context.h>
  30 #include <asm/cacheflush.h>
  31 #include <asm/kgdb.h>
  32
  33 extern void die(const char *,struct pt_regs *,long);
  34
  35 /*
  36  * This routine handles page faults.  It determines the address,
  37  * and the problem, and then passes it off to one of the appropriate
  38  * routines.
  39  */
  40 asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long writeaccess,
  41                               unsigned long address)
  42 {
  43         struct task_struct *tsk;
  44         struct mm_struct *mm;
  45         struct vm_area_struct * vma;
  46         unsigned long page;
  47
  48 #ifdef CONFIG_SH_KGDB
  49         if (kgdb_nofault && kgdb_bus_err_hook)
  50                 kgdb_bus_err_hook();
  51 #endif
  52
  53         tsk = current;
  54         mm = tsk->mm;
  55
  56         /*
  57          * If we're in an interrupt or have no user
  58          * context, we must not take the fault..
  59          */
  60         if (in_atomic() || !mm)
  61                 goto no_context;
  62
  63         down_read(&mm->mmap_sem);
  64
  65         vma = find_vma(mm, address);
  66         if (!vma)
  67                 goto bad_area;
  68         if (vma->vm_start <= address)
  69                 goto good_area;
  70         if (!(vma->vm_flags & VM_GROWSDOWN))
  71                 goto bad_area;
  72         if (expand_stack(vma, address))
  73                 goto bad_area;
  74 /*
  75  * Ok, we have a good vm_area for this memory access, so
  76  * we can handle it..
  77  */
  78 good_area:
  79         if (writeaccess) {
  80                 if (!(vma->vm_flags & VM_WRITE))
  81                         goto bad_area;
  82         } else {
  83                 if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
  84                         goto bad_area;
  85         }
  86
  87         /*
  88          * If for any reason at all we couldn't handle the fault,
  89          * make sure we exit gracefully rather than endlessly redo
  90          * the fault.
  91          */
  92 survive:
  93         switch (handle_mm_fault(mm, vma, address, writeaccess)) {
  94                 case VM_FAULT_MINOR:
  95                         tsk->min_flt++;
  96                         break;
  97                 case VM_FAULT_MAJOR:
  98                         tsk->maj_flt++;
  99                         break;
 100                 case VM_FAULT_SIGBUS:
 101                         goto do_sigbus;
 102                 case VM_FAULT_OOM:
 103                         goto out_of_memory;
 104                 default:
 105                         BUG();
 106         }
 107
 108         up_read(&mm->mmap_sem);
 109         return;
 110
 111 /*
 112  * Something tried to access memory that isn't in our memory map..
 113  * Fix it, but check if it's kernel or user first..
 114  */
 115 bad_area:
 116         up_read(&mm->mmap_sem);
 117
 118         if (user_mode(regs)) {
 119                 tsk->thread.address = address;
 120                 tsk->thread.error_code = writeaccess;
 121                 force_sig(SIGSEGV, tsk);
 122                 return;
 123         }
 124
 125 no_context:
 126         /* Are we prepared to handle this kernel fault?  */
 127         if (fixup_exception(regs))
 128                 return;
 129
 130 /*
 131  * Oops. The kernel tried to access some bad page. We'll have to
 132  * terminate things with extreme prejudice.
 133  *
 134  */
 135         if (address < PAGE_SIZE)
 136                 printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference");
 137         else
 138                 printk(KERN_ALERT "Unable to handle kernel paging request");
 139         printk(" at virtual address %08lx\n", address);
 140         printk(KERN_ALERT "pc = %08lx\n", regs->pc);
 141         asm volatile("mov.l     %1, %0"
 142                      : "=r" (page)
 143                      : "m" (__m(MMU_TTB)));
 144         if (page) {
 145                 page = ((unsigned long *) page)[address >> 22];
 146                 printk(KERN_ALERT "*pde = %08lx\n", page);
 147                 if (page & _PAGE_PRESENT) {
 148                         page &= PAGE_MASK;
 149                         address &= 0x003ff000;
 150                         page = ((unsigned long *) __va(page))[address >> PAGE_SHIFT];
 151                         printk(KERN_ALERT "*pte = %08lx\n", page);
 152                 }
 153         }
 154         die("Oops", regs, writeaccess);
 155         do_exit(SIGKILL);
 156
 157 /*
 158  * We ran out of memory, or some other thing happened to us that made
 159  * us unable to handle the page fault gracefully.
 160  */
 161 out_of_memory:
 162         up_read(&mm->mmap_sem);
 163         if (current->pid == 1) {
 164                 yield();
 165                 down_read(&mm->mmap_sem);
 166                 goto survive;
 167         }
 168         printk("VM: killing process %s\n", tsk->comm);
 169         if (user_mode(regs))
 170                 do_exit(SIGKILL);
 171         goto no_context;
 172
 173 do_sigbus:
 174         up_read(&mm->mmap_sem);
 175
 176         /*
 177          * Send a sigbus, regardless of whether we were in kernel
 178          * or user mode.
 179          */
 180         tsk->thread.address = address;
 181         tsk->thread.error_code = writeaccess;
 182         tsk->thread.trap_no = 14;
 183         force_sig(SIGBUS, tsk);
 184
 185         /* Kernel mode? Handle exceptions or die */
 186         if (!user_mode(regs))
 187                 goto no_context;
 188 }
 189
 190 /*
 191  * Called with interrupt disabled.
 192  */
 193 asmlinkage int __do_page_fault(struct pt_regs *regs, unsigned long writeaccess,
 194                                unsigned long address)
 195 {
 196         unsigned long addrmax = P4SEG;
 197         pgd_t *pgd;
 198         pmd_t *pmd;
 199         pte_t *pte;
 200         pte_t entry;
 201         struct mm_struct *mm;
 202         spinlock_t *ptl;
 203         int ret = 1;
 204
 205 #ifdef CONFIG_SH_KGDB
 206         if (kgdb_nofault && kgdb_bus_err_hook)
 207                 kgdb_bus_err_hook();
 208 #endif
 209
 210 #ifdef CONFIG_SH_STORE_QUEUES
 211         addrmax = P4SEG_STORE_QUE + 0x04000000;
 212 #endif
 213
 214         if (address >= P3SEG && address < addrmax) {
 215                 pgd = pgd_offset_k(address);
 216                 mm = NULL;
 217         } else if (address >= TASK_SIZE)
 218                 return 1;
 219         else if (!(mm = current->mm))
 220                 return 1;
 221         else
 222                 pgd = pgd_offset(mm, address);
 223
 224         pmd = pmd_offset(pgd, address);
 225         if (pmd_none_or_clear_bad(pmd))
 226                 return 1;
 227         if (mm)
 228                 pte = pte_offset_map_lock(mm, pmd, address, &ptl);
 229         else
 230                 pte = pte_offset_kernel(pmd, address);
 231
 232         entry = *pte;
 233         if (pte_none(entry) || pte_not_present(entry)
 234             || (writeaccess && !pte_write(entry)))
 235                 goto unlock;
 236
 237         if (writeaccess)
 238                 entry = pte_mkdirty(entry);
 239         entry = pte_mkyoung(entry);
 240
 241 #ifdef CONFIG_CPU_SH4
 242         /*
 243          * ITLB is not affected by "ldtlb" instruction.
 244          * So, we need to flush the entry by ourselves.
 245          */
 246
 247         {
 248                 unsigned long flags;
 249                 local_irq_save(flags);
 250                 __flush_tlb_page(get_asid(), address&PAGE_MASK);
 251                 local_irq_restore(flags);
 252         }
 253 #endif
 254
 255         set_pte(pte, entry);
 256         update_mmu_cache(NULL, address, entry);
 257         ret = 0;
 258 unlock:
 259         if (mm)
 260                 pte_unmap_unlock(pte, ptl);
 261         return ret;
 262 }
 263
 264 void flush_tlb_page(struct vm_area_struct *vma, unsigned long page)
 265 {
 266         if (vma->vm_mm && vma->vm_mm->context != NO_CONTEXT) {
 267                 unsigned long flags;
 268                 unsigned long asid;
 269                 unsigned long saved_asid = MMU_NO_ASID;
 270
 271                 asid = vma->vm_mm->context & MMU_CONTEXT_ASID_MASK;
 272                 page &= PAGE_MASK;
 273
 274                 local_irq_save(flags);
 275                 if (vma->vm_mm != current->mm) {
 276                         saved_asid = get_asid();
 277                         set_asid(asid);
 278                 }
 279                 __flush_tlb_page(asid, page);
 280                 if (saved_asid != MMU_NO_ASID)
 281                         set_asid(saved_asid);
 282                 local_irq_restore(flags);
 283         }
 284 }
 285
 286 void flush_tlb_range(struct vm_area_struct *vma, unsigned long start,
 287                      unsigned long end)
 288 {
 289         struct mm_struct *mm = vma->vm_mm;
 290
 291         if (mm->context != NO_CONTEXT) {
 292                 unsigned long flags;
 293                 int size;
 294
 295                 local_irq_save(flags);
 296                 size = (end - start + (PAGE_SIZE - 1)) >> PAGE_SHIFT;
 297                 if (size > (MMU_NTLB_ENTRIES/4)) { /* Too many TLB to flush */
 298                         mm->context = NO_CONTEXT;
 299                         if (mm == current->mm)
 300                                 activate_context(mm);
 301                 } else {
 302                         unsigned long asid = mm->context&MMU_CONTEXT_ASID_MASK;
 303                         unsigned long saved_asid = MMU_NO_ASID;
 304
 305                         start &= PAGE_MASK;
 306                         end += (PAGE_SIZE - 1);
 307                         end &= PAGE_MASK;
 308                         if (mm != current->mm) {
 309                                 saved_asid = get_asid();
 310                                 set_asid(asid);
 311                         }
 312                         while (start < end) {
 313                                 __flush_tlb_page(asid, start);
 314                                 start += PAGE_SIZE;
 315                         }
 316                         if (saved_asid != MMU_NO_ASID)
 317                                 set_asid(saved_asid);
 318                 }
 319                 local_irq_restore(flags);
 320         }
 321 }
 322
 323 void flush_tlb_kernel_range(unsigned long start, unsigned long end)
 324 {
 325         unsigned long flags;
 326         int size;
 327
 328         local_irq_save(flags);
 329         size = (end - start + (PAGE_SIZE - 1)) >> PAGE_SHIFT;
 330         if (size > (MMU_NTLB_ENTRIES/4)) { /* Too many TLB to flush */
 331                 flush_tlb_all();
 332         } else {
 333                 unsigned long asid = init_mm.context&MMU_CONTEXT_ASID_MASK;
 334                 unsigned long saved_asid = get_asid();
 335
 336                 start &= PAGE_MASK;
 337                 end += (PAGE_SIZE - 1);
 338                 end &= PAGE_MASK;
 339                 set_asid(asid);
 340                 while (start < end) {
 341                         __flush_tlb_page(asid, start);
 342                         start += PAGE_SIZE;
 343                 }
 344                 set_asid(saved_asid);
 345         }
 346         local_irq_restore(flags);
 347 }
 348
 349 void flush_tlb_mm(struct mm_struct *mm)
 350 {
 351         /* Invalidate all TLB of this process. */
 352         /* Instead of invalidating each TLB, we get new MMU context. */
 353         if (mm->context != NO_CONTEXT) {
 354                 unsigned long flags;
 355
 356                 local_irq_save(flags);
 357                 mm->context = NO_CONTEXT;
 358                 if (mm == current->mm)
 359                         activate_context(mm);
 360                 local_irq_restore(flags);
 361         }
 362 }
 363
 364 void flush_tlb_all(void)
 365 {
 366         unsigned long flags, status;
 367
 368         /*
 369          * Flush all the TLB.
 370          *
 371          * Write to the MMU control register's bit:
 372          *      TF-bit for SH-3, TI-bit for SH-4.
 373          *      It's same position, bit #2.
 374          */
 375         local_irq_save(flags);
 376         status = ctrl_inl(MMUCR);
 377         status |= 0x04;
 378         ctrl_outl(status, MMUCR);
 379         local_irq_restore(flags);
 380 }