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 #include <linux/uaccess.h>
  23
  24 #include <asm/pgtable.h>
  25 #include <asm/gdb-stub.h>
  26
  27 /*****************************************************************************/
  28 /*
  29  * This routine handles page faults.  It determines the problem, and
  30  * then passes it off to one of the appropriate routines.
  31  */
  32 asmlinkage void do_page_fault(int datammu, unsigned long esr0, unsigned long ear0)
  33 {
  34         struct vm_area_struct *vma;
  35         struct mm_struct *mm;
  36         unsigned long _pme, lrai, lrad, fixup;
  37         unsigned long flags = 0;
  38         siginfo_t info;
  39         pgd_t *pge;
  40         pud_t *pue;
  41         pte_t *pte;
  42         int fault;
  43
  44 #if 0
  45         const char *atxc[16] = {
  46                 [0x0] = "mmu-miss", [0x8] = "multi-dat", [0x9] = "multi-sat",
  47                 [0xa] = "tlb-miss", [0xc] = "privilege", [0xd] = "write-prot",
  48         };
  49
  50         printk("do_page_fault(%d,%lx [%s],%lx)\n",
  51                datammu, esr0, atxc[esr0 >> 20 & 0xf], ear0);
  52 #endif
  53
  54         mm = current->mm;
  55
  56         /*
  57          * We fault-in kernel-space virtual memory on-demand. The
  58          * 'reference' page table is init_mm.pgd.
  59          *
  60          * NOTE! We MUST NOT take any locks for this case. We may
  61          * be in an interrupt or a critical region, and should
  62          * only copy the information from the master page table,
  63          * nothing more.
  64          *
  65          * This verifies that the fault happens in kernel space
  66          * and that the fault was a page not present (invalid) error
  67          */
  68         if (!user_mode(__frame) && (esr0 & ESR0_ATXC) == ESR0_ATXC_AMRTLB_MISS) {
  69                 if (ear0 >= VMALLOC_START && ear0 < VMALLOC_END)
  70                         goto kernel_pte_fault;
  71                 if (ear0 >= PKMAP_BASE && ear0 < PKMAP_END)
  72                         goto kernel_pte_fault;
  73         }
  74
  75         info.si_code = SEGV_MAPERR;
  76
  77         /*
  78          * If we're in an interrupt or have no user
  79          * context, we must not take the fault..
  80          */
  81         if (faulthandler_disabled() || !mm)
  82                 goto no_context;
  83
  84         if (user_mode(__frame))
  85                 flags |= FAULT_FLAG_USER;
  86
  87         down_read(&mm->mmap_sem);
  88
  89         vma = find_vma(mm, ear0);
  90         if (!vma)
  91                 goto bad_area;
  92         if (vma->vm_start <= ear0)
  93                 goto good_area;
  94         if (!(vma->vm_flags & VM_GROWSDOWN))
  95                 goto bad_area;
  96
  97         if (user_mode(__frame)) {
  98                 /*
  99                  * accessing the stack below %esp is always a bug.
 100                  * The "+ 32" is there due to some instructions (like
 101                  * pusha) doing post-decrement on the stack and that
 102                  * doesn't show up until later..
 103                  */
 104                 if ((ear0 & PAGE_MASK) + 2 * PAGE_SIZE < __frame->sp) {
 105 #if 0
 106                         printk("[%d] ### Access below stack @%lx (sp=%lx)\n",
 107                                current->pid, ear0, __frame->sp);
 108                         show_registers(__frame);
 109                         printk("[%d] ### Code: [%08lx] %02x %02x %02x %02x %02x %02x %02x %02x\n",
 110                                current->pid,
 111                                __frame->pc,
 112                                ((u8*)__frame->pc)[0],
 113                                ((u8*)__frame->pc)[1],
 114                                ((u8*)__frame->pc)[2],
 115                                ((u8*)__frame->pc)[3],
 116                                ((u8*)__frame->pc)[4],
 117                                ((u8*)__frame->pc)[5],
 118                                ((u8*)__frame->pc)[6],
 119                                ((u8*)__frame->pc)[7]
 120                                );
 121 #endif
 122                         goto bad_area;
 123                 }
 124         }
 125
 126         if (expand_stack(vma, ear0))
 127                 goto bad_area;
 128
 129 /*
 130  * Ok, we have a good vm_area for this memory access, so
 131  * we can handle it..
 132  */
 133  good_area:
 134         info.si_code = SEGV_ACCERR;
 135         switch (esr0 & ESR0_ATXC) {
 136         default:
 137                 /* handle write to write protected page */
 138         case ESR0_ATXC_WP_EXCEP:
 139 #ifdef TEST_VERIFY_AREA
 140                 if (!(user_mode(__frame)))
 141                         printk("WP fault at %08lx\n", __frame->pc);
 142 #endif
 143                 if (!(vma->vm_flags & VM_WRITE))
 144                         goto bad_area;
 145                 flags |= FAULT_FLAG_WRITE;
 146                 break;
 147
 148                  /* handle read from protected page */
 149         case ESR0_ATXC_PRIV_EXCEP:
 150                 goto bad_area;
 151
 152                  /* handle read, write or exec on absent page
 153                   * - can't support write without permitting read
 154                   * - don't support execute without permitting read and vice-versa
 155                   */
 156         case ESR0_ATXC_AMRTLB_MISS:
 157                 if (!(vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC)))
 158                         goto bad_area;
 159                 break;
 160         }
 161
 162         /*
 163          * If for any reason at all we couldn't handle the fault,
 164          * make sure we exit gracefully rather than endlessly redo
 165          * the fault.
 166          */
 167         fault = handle_mm_fault(vma, ear0, flags);
 168         if (unlikely(fault & VM_FAULT_ERROR)) {
 169                 if (fault & VM_FAULT_OOM)
 170                         goto out_of_memory;
 171                 else if (fault & VM_FAULT_SIGSEGV)
 172                         goto bad_area;
 173                 else if (fault & VM_FAULT_SIGBUS)
 174                         goto do_sigbus;
 175                 BUG();
 176         }
 177         if (fault & VM_FAULT_MAJOR)
 178                 current->maj_flt++;
 179         else
 180                 current->min_flt++;
 181
 182         up_read(&mm->mmap_sem);
 183         return;
 184
 185 /*
 186  * Something tried to access memory that isn't in our memory map..
 187  * Fix it, but check if it's kernel or user first..
 188  */
 189  bad_area:
 190         up_read(&mm->mmap_sem);
 191
 192         /* User mode accesses just cause a SIGSEGV */
 193         if (user_mode(__frame)) {
 194                 info.si_signo = SIGSEGV;
 195                 info.si_errno = 0;
 196                 /* info.si_code has been set above */
 197                 info.si_addr = (void *) ear0;
 198                 force_sig_info(SIGSEGV, &info, current);
 199                 return;
 200         }
 201
 202  no_context:
 203         /* are we prepared to handle this kernel fault? */
 204         if ((fixup = search_exception_table(__frame->pc)) != 0) {
 205                 __frame->pc = fixup;
 206                 return;
 207         }
 208
 209 /*
 210  * Oops. The kernel tried to access some bad page. We'll have to
 211  * terminate things with extreme prejudice.
 212  */
 213
 214         bust_spinlocks(1);
 215
 216         if (ear0 < PAGE_SIZE)
 217                 printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference");
 218         else
 219                 printk(KERN_ALERT "Unable to handle kernel paging request");
 220         printk(" at virtual addr %08lx\n", ear0);
 221         printk("  PC  : %08lx\n", __frame->pc);
 222         printk("  EXC : esr0=%08lx ear0=%08lx\n", esr0, ear0);
 223
 224         asm("lrai %1,%0,#1,#0,#0" : "=&r"(lrai) : "r"(ear0));
 225         asm("lrad %1,%0,#1,#0,#0" : "=&r"(lrad) : "r"(ear0));
 226
 227         printk(KERN_ALERT "  LRAI: %08lx\n", lrai);
 228         printk(KERN_ALERT "  LRAD: %08lx\n", lrad);
 229
 230         __break_hijack_kernel_event();
 231
 232         pge = pgd_offset(current->mm, ear0);
 233         pue = pud_offset(pge, ear0);
 234         _pme = pue->pue[0].ste[0];
 235
 236         printk(KERN_ALERT "  PGE : %8p { PME %08lx }\n", pge, _pme);
 237
 238         if (_pme & xAMPRx_V) {
 239                 unsigned long dampr, damlr, val;
 240
 241                 asm volatile("movsg dampr2,%0 ! movgs %2,dampr2 ! movsg damlr2,%1"
 242                              : "=&r"(dampr), "=r"(damlr)
 243                              : "r" (_pme | xAMPRx_L|xAMPRx_SS_16Kb|xAMPRx_S|xAMPRx_C|xAMPRx_V)
 244                              );
 245
 246                 pte = (pte_t *) damlr + __pte_index(ear0);
 247                 val = pte_val(*pte);
 248
 249                 asm volatile("movgs %0,dampr2" :: "r" (dampr));
 250
 251                 printk(KERN_ALERT "  PTE : %8p { %08lx }\n", pte, val);
 252         }
 253
 254         die_if_kernel("Oops\n");
 255         do_exit(SIGKILL);
 256
 257 /*
 258  * We ran out of memory, or some other thing happened to us that made
 259  * us unable to handle the page fault gracefully.
 260  */
 261  out_of_memory:
 262         up_read(&mm->mmap_sem);
 263         if (!user_mode(__frame))
 264                 goto no_context;
 265         pagefault_out_of_memory();
 266         return;
 267
 268  do_sigbus:
 269         up_read(&mm->mmap_sem);
 270
 271         /*
 272          * Send a sigbus, regardless of whether we were in kernel
 273          * or user mode.
 274          */
 275         info.si_signo = SIGBUS;
 276         info.si_errno = 0;
 277         info.si_code = BUS_ADRERR;
 278         info.si_addr = (void *) ear0;
 279         force_sig_info(SIGBUS, &info, current);
 280
 281         /* Kernel mode? Handle exceptions or die */
 282         if (!user_mode(__frame))
 283                 goto no_context;
 284         return;
 285
 286 /*
 287  * The fault was caused by a kernel PTE (such as installed by vmalloc or kmap)
 288  */
 289  kernel_pte_fault:
 290         {
 291                 /*
 292                  * Synchronize this task's top level page-table
 293                  * with the 'reference' page table.
 294                  *
 295                  * Do _not_ use "tsk" here. We might be inside
 296                  * an interrupt in the middle of a task switch..
 297                  */
 298                 int index = pgd_index(ear0);
 299                 pgd_t *pgd, *pgd_k;
 300                 pud_t *pud, *pud_k;
 301                 pmd_t *pmd, *pmd_k;
 302                 pte_t *pte_k;
 303
 304                 pgd = (pgd_t *) __get_TTBR();
 305                 pgd = (pgd_t *)__va(pgd) + index;
 306                 pgd_k = ((pgd_t *)(init_mm.pgd)) + index;
 307
 308                 if (!pgd_present(*pgd_k))
 309                         goto no_context;
 310                 //set_pgd(pgd, *pgd_k); /////// gcc ICE's on this line
 311
 312                 pud_k = pud_offset(pgd_k, ear0);
 313                 if (!pud_present(*pud_k))
 314                         goto no_context;
 315
 316                 pmd_k = pmd_offset(pud_k, ear0);
 317                 if (!pmd_present(*pmd_k))
 318                         goto no_context;
 319
 320                 pud = pud_offset(pgd, ear0);
 321                 pmd = pmd_offset(pud, ear0);
 322                 set_pmd(pmd, *pmd_k);
 323
 324                 pte_k = pte_offset_kernel(pmd_k, ear0);
 325                 if (!pte_present(*pte_k))
 326                         goto no_context;
 327                 return;
 328         }
 329 } /* end do_page_fault() */