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