release/src-rt-6.x.4708/linux/linux-2.6.36/arch/frv/mm/fault.c

   1 /*
   2  *  linux/arch/frv/mm/fault.c
   3  *
   4  * Copyright (C) 2003 Red Hat, Inc. All Rights Reserved.
   5  * - Written by David Howells (dhowells@redhat.com)
   6  * - Derived from arch/m68knommu/mm/fault.c
   7  *   - Copyright (C) 1998  D. Jeff Dionne <jeff@lineo.ca>,
   8  *   - Copyright (C) 2000  Lineo, Inc.  (www.lineo.com)
   9  *
  10  *  Based on:
  11  *
  12  *  linux/arch/m68k/mm/fault.c
  13  *
  14  *  Copyright (C) 1995  Hamish Macdonald
  15  */
  16
  17 #include <linux/mman.h>
  18 #include <linux/mm.h>
  19 #include <linux/kernel.h>
  20 #include <linux/ptrace.h>
  21 #include <linux/hardirq.h>
  22
  23 #include <asm/system.h>
  24 #include <asm/pgtable.h>
  25 #include <asm/uaccess.h>
  26 #include <asm/gdb-stub.h>
  27
  28 /*****************************************************************************/
  29 /*
  30  * This routine handles page faults.  It determines the problem, and
  31  * then passes it off to one of the appropriate routines.
  32  */
  33 asmlinkage void do_page_fault(int datammu, unsigned long esr0, unsigned long ear0)
  34 {
  35         struct vm_area_struct *vma;
  36         struct mm_struct *mm;
  37         unsigned long _pme, lrai, lrad, fixup;
  38         siginfo_t info;
  39         pgd_t *pge;
  40         pud_t *pue;
  41         pte_t *pte;
  42         int write;
  43         int fault;
  44
  45
  46         mm = current->mm;
  47
  48         /*
  49          * We fault-in kernel-space virtual memory on-demand. The
  50          * 'reference' page table is init_mm.pgd.
  51          *
  52          * NOTE! We MUST NOT take any locks for this case. We may
  53          * be in an interrupt or a critical region, and should
  54          * only copy the information from the master page table,
  55          * nothing more.
  56          *
  57          * This verifies that the fault happens in kernel space
  58          * and that the fault was a page not present (invalid) error
  59          */
  60         if (!user_mode(__frame) && (esr0 & ESR0_ATXC) == ESR0_ATXC_AMRTLB_MISS) {
  61                 if (ear0 >= VMALLOC_START && ear0 < VMALLOC_END)
  62                         goto kernel_pte_fault;
  63                 if (ear0 >= PKMAP_BASE && ear0 < PKMAP_END)
  64                         goto kernel_pte_fault;
  65         }
  66
  67         info.si_code = SEGV_MAPERR;
  68
  69         /*
  70          * If we're in an interrupt or have no user
  71          * context, we must not take the fault..
  72          */
  73         if (in_atomic() || !mm)
  74                 goto no_context;
  75
  76         down_read(&mm->mmap_sem);
  77
  78         vma = find_vma(mm, ear0);
  79         if (!vma)
  80                 goto bad_area;
  81         if (vma->vm_start <= ear0)
  82                 goto good_area;
  83         if (!(vma->vm_flags & VM_GROWSDOWN))
  84                 goto bad_area;
  85
  86         if (user_mode(__frame)) {
  87                 /*
  88                  * accessing the stack below %esp is always a bug.
  89                  * The "+ 32" is there due to some instructions (like
  90                  * pusha) doing post-decrement on the stack and that
  91                  * doesn't show up until later..
  92                  */
  93                 if ((ear0 & PAGE_MASK) + 2 * PAGE_SIZE < __frame->sp) {
  94                         goto bad_area;
  95                 }
  96         }
  97
  98         if (expand_stack(vma, ear0))
  99                 goto bad_area;
 100
 101 /*
 102  * Ok, we have a good vm_area for this memory access, so
 103  * we can handle it..
 104  */
 105  good_area:
 106         info.si_code = SEGV_ACCERR;
 107         write = 0;
 108         switch (esr0 & ESR0_ATXC) {
 109         default:
 110                 /* handle write to write protected page */
 111         case ESR0_ATXC_WP_EXCEP:
 112 #ifdef TEST_VERIFY_AREA
 113                 if (!(user_mode(__frame)))
 114                         printk("WP fault at %08lx\n", __frame->pc);
 115 #endif
 116                 if (!(vma->vm_flags & VM_WRITE))
 117                         goto bad_area;
 118                 write = 1;
 119                 break;
 120
 121                  /* handle read from protected page */
 122         case ESR0_ATXC_PRIV_EXCEP:
 123                 goto bad_area;
 124
 125                  /* handle read, write or exec on absent page
 126                   * - can't support write without permitting read
 127                   * - don't support execute without permitting read and vice-versa
 128                   */
 129         case ESR0_ATXC_AMRTLB_MISS:
 130                 if (!(vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC)))
 131                         goto bad_area;
 132                 break;
 133         }
 134
 135         /*
 136          * If for any reason at all we couldn't handle the fault,
 137          * make sure we exit gracefully rather than endlessly redo
 138          * the fault.
 139          */
 140         fault = handle_mm_fault(mm, vma, ear0, write ? FAULT_FLAG_WRITE : 0);
 141         if (unlikely(fault & VM_FAULT_ERROR)) {
 142                 if (fault & VM_FAULT_OOM)
 143                         goto out_of_memory;
 144                 else if (fault & VM_FAULT_SIGBUS)
 145                         goto do_sigbus;
 146                 BUG();
 147         }
 148         if (fault & VM_FAULT_MAJOR)
 149                 current->maj_flt++;
 150         else
 151                 current->min_flt++;
 152
 153         up_read(&mm->mmap_sem);
 154         return;
 155
 156 /*
 157  * Something tried to access memory that isn't in our memory map..
 158  * Fix it, but check if it's kernel or user first..
 159  */
 160  bad_area:
 161         up_read(&mm->mmap_sem);
 162
 163         /* User mode accesses just cause a SIGSEGV */
 164         if (user_mode(__frame)) {
 165                 info.si_signo = SIGSEGV;
 166                 info.si_errno = 0;
 167                 /* info.si_code has been set above */
 168                 info.si_addr = (void *) ear0;
 169                 force_sig_info(SIGSEGV, &info, current);
 170                 return;
 171         }
 172
 173  no_context:
 174         /* are we prepared to handle this kernel fault? */
 175         if ((fixup = search_exception_table(__frame->pc)) != 0) {
 176                 __frame->pc = fixup;
 177                 return;
 178         }
 179
 180 /*
 181  * Oops. The kernel tried to access some bad page. We'll have to
 182  * terminate things with extreme prejudice.
 183  */
 184
 185         bust_spinlocks(1);
 186
 187         if (ear0 < PAGE_SIZE)
 188                 printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference");
 189         else
 190                 printk(KERN_ALERT "Unable to handle kernel paging request");
 191         printk(" at virtual addr %08lx\n", ear0);
 192         printk("  PC  : %08lx\n", __frame->pc);
 193         printk("  EXC : esr0=%08lx ear0=%08lx\n", esr0, ear0);
 194
 195         asm("lrai %1,%0,#1,#0,#0" : "=&r"(lrai) : "r"(ear0));
 196         asm("lrad %1,%0,#1,#0,#0" : "=&r"(lrad) : "r"(ear0));
 197
 198         printk(KERN_ALERT "  LRAI: %08lx\n", lrai);
 199         printk(KERN_ALERT "  LRAD: %08lx\n", lrad);
 200
 201         __break_hijack_kernel_event();
 202
 203         pge = pgd_offset(current->mm, ear0);
 204         pue = pud_offset(pge, ear0);
 205         _pme = pue->pue[0].ste[0];
 206
 207         printk(KERN_ALERT "  PGE : %8p { PME %08lx }\n", pge, _pme);
 208
 209         if (_pme & xAMPRx_V) {
 210                 unsigned long dampr, damlr, val;
 211
 212                 asm volatile("movsg dampr2,%0 ! movgs %2,dampr2 ! movsg damlr2,%1"
 213                              : "=&r"(dampr), "=r"(damlr)
 214                              : "r" (_pme | xAMPRx_L|xAMPRx_SS_16Kb|xAMPRx_S|xAMPRx_C|xAMPRx_V)
 215                              );
 216
 217                 pte = (pte_t *) damlr + __pte_index(ear0);
 218                 val = pte_val(*pte);
 219
 220                 asm volatile("movgs %0,dampr2" :: "r" (dampr));
 221
 222                 printk(KERN_ALERT "  PTE : %8p { %08lx }\n", pte, val);
 223         }
 224
 225         die_if_kernel("Oops\n");
 226         do_exit(SIGKILL);
 227
 228 /*
 229  * We ran out of memory, or some other thing happened to us that made
 230  * us unable to handle the page fault gracefully.
 231  */
 232  out_of_memory:
 233         up_read(&mm->mmap_sem);
 234         if (!user_mode(__frame))
 235                 goto no_context;
 236         pagefault_out_of_memory();
 237         return;
 238
 239  do_sigbus:
 240         up_read(&mm->mmap_sem);
 241
 242         /*
 243          * Send a sigbus, regardless of whether we were in kernel
 244          * or user mode.
 245          */
 246         info.si_signo = SIGBUS;
 247         info.si_errno = 0;
 248         info.si_code = BUS_ADRERR;
 249         info.si_addr = (void *) ear0;
 250         force_sig_info(SIGBUS, &info, current);
 251
 252         /* Kernel mode? Handle exceptions or die */
 253         if (!user_mode(__frame))
 254                 goto no_context;
 255         return;
 256
 257 /*
 258  * The fault was caused by a kernel PTE (such as installed by vmalloc or kmap)
 259  */
 260  kernel_pte_fault:
 261         {
 262                 /*
 263                  * Synchronize this task's top level page-table
 264                  * with the 'reference' page table.
 265                  *
 266                  * Do _not_ use "tsk" here. We might be inside
 267                  * an interrupt in the middle of a task switch..
 268                  */
 269                 int index = pgd_index(ear0);
 270                 pgd_t *pgd, *pgd_k;
 271                 pud_t *pud, *pud_k;
 272                 pmd_t *pmd, *pmd_k;
 273                 pte_t *pte_k;
 274
 275                 pgd = (pgd_t *) __get_TTBR();
 276                 pgd = (pgd_t *)__va(pgd) + index;
 277                 pgd_k = ((pgd_t *)(init_mm.pgd)) + index;
 278
 279                 if (!pgd_present(*pgd_k))
 280                         goto no_context;
 281                 //set_pgd(pgd, *pgd_k); /////// gcc ICE's on this line
 282
 283                 pud_k = pud_offset(pgd_k, ear0);
 284                 if (!pud_present(*pud_k))
 285                         goto no_context;
 286
 287                 pmd_k = pmd_offset(pud_k, ear0);
 288                 if (!pmd_present(*pmd_k))
 289                         goto no_context;
 290
 291                 pud = pud_offset(pgd, ear0);
 292                 pmd = pmd_offset(pud, ear0);
 293                 set_pmd(pmd, *pmd_k);
 294
 295                 pte_k = pte_offset_kernel(pmd_k, ear0);
 296                 if (!pte_present(*pte_k))
 297                         goto no_context;
 298                 return;
 299         }
 300 } /* end do_page_fault() */