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/pgtable.h>
  24 #include <asm/uaccess.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         siginfo_t info;
  38         pgd_t *pge;
  39         pud_t *pue;
  40         pte_t *pte;
  41         int write;
  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 (in_atomic() || !mm)
  82                 goto no_context;
  83
  84         down_read(&mm->mmap_sem);
  85
  86         vma = find_vma(mm, ear0);
  87         if (!vma)
  88                 goto bad_area;
  89         if (vma->vm_start <= ear0)
  90                 goto good_area;
  91         if (!(vma->vm_flags & VM_GROWSDOWN))
  92                 goto bad_area;
  93
  94         if (user_mode(__frame)) {
  95                 /*
  96                  * accessing the stack below %esp is always a bug.
  97                  * The "+ 32" is there due to some instructions (like
  98                  * pusha) doing post-decrement on the stack and that
  99                  * doesn't show up until later..
 100                  */
 101                 if ((ear0 & PAGE_MASK) + 2 * PAGE_SIZE < __frame->sp) {
 102 #if 0
 103                         printk("[%d] ### Access below stack @%lx (sp=%lx)\n",
 104                                current->pid, ear0, __frame->sp);
 105                         show_registers(__frame);
 106                         printk("[%d] ### Code: [%08lx] %02x %02x %02x %02x %02x %02x %02x %02x\n",
 107                                current->pid,
 108                                __frame->pc,
 109                                ((u8*)__frame->pc)[0],
 110                                ((u8*)__frame->pc)[1],
 111                                ((u8*)__frame->pc)[2],
 112                                ((u8*)__frame->pc)[3],
 113                                ((u8*)__frame->pc)[4],
 114                                ((u8*)__frame->pc)[5],
 115                                ((u8*)__frame->pc)[6],
 116                                ((u8*)__frame->pc)[7]
 117                                );
 118 #endif
 119                         goto bad_area;
 120                 }
 121         }
 122
 123         if (expand_stack(vma, ear0))
 124                 goto bad_area;
 125
 126 /*
 127  * Ok, we have a good vm_area for this memory access, so
 128  * we can handle it..
 129  */
 130  good_area:
 131         info.si_code = SEGV_ACCERR;
 132         write = 0;
 133         switch (esr0 & ESR0_ATXC) {
 134         default:
 135                 /* handle write to write protected page */
 136         case ESR0_ATXC_WP_EXCEP:
 137 #ifdef TEST_VERIFY_AREA
 138                 if (!(user_mode(__frame)))
 139                         printk("WP fault at %08lx\n", __frame->pc);
 140 #endif
 141                 if (!(vma->vm_flags & VM_WRITE))
 142                         goto bad_area;
 143                 write = 1;
 144                 break;
 145
 146                  /* handle read from protected page */
 147         case ESR0_ATXC_PRIV_EXCEP:
 148                 goto bad_area;
 149
 150                  /* handle read, write or exec on absent page
 151                   * - can't support write without permitting read
 152                   * - don't support execute without permitting read and vice-versa
 153                   */
 154         case ESR0_ATXC_AMRTLB_MISS:
 155                 if (!(vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC)))
 156                         goto bad_area;
 157                 break;
 158         }
 159
 160         /*
 161          * If for any reason at all we couldn't handle the fault,
 162          * make sure we exit gracefully rather than endlessly redo
 163          * the fault.
 164          */
 165         fault = handle_mm_fault(mm, vma, ear0, write ? FAULT_FLAG_WRITE : 0);
 166         if (unlikely(fault & VM_FAULT_ERROR)) {
 167                 if (fault & VM_FAULT_OOM)
 168                         goto out_of_memory;
 169                 else if (fault & VM_FAULT_SIGBUS)
 170                         goto do_sigbus;
 171                 BUG();
 172         }
 173         if (fault & VM_FAULT_MAJOR)
 174                 current->maj_flt++;
 175         else
 176                 current->min_flt++;
 177
 178         up_read(&mm->mmap_sem);
 179         return;
 180
 181 /*
 182  * Something tried to access memory that isn't in our memory map..
 183  * Fix it, but check if it's kernel or user first..
 184  */
 185  bad_area:
 186         up_read(&mm->mmap_sem);
 187
 188         /* User mode accesses just cause a SIGSEGV */
 189         if (user_mode(__frame)) {
 190                 info.si_signo = SIGSEGV;
 191                 info.si_errno = 0;
 192                 /* info.si_code has been set above */
 193                 info.si_addr = (void *) ear0;
 194                 force_sig_info(SIGSEGV, &info, current);
 195                 return;
 196         }
 197
 198  no_context:
 199         /* are we prepared to handle this kernel fault? */
 200         if ((fixup = search_exception_table(__frame->pc)) != 0) {
 201                 __frame->pc = fixup;
 202                 return;
 203         }
 204
 205 /*
 206  * Oops. The kernel tried to access some bad page. We'll have to
 207  * terminate things with extreme prejudice.
 208  */
 209
 210         bust_spinlocks(1);
 211
 212         if (ear0 < PAGE_SIZE)
 213                 printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference");
 214         else
 215                 printk(KERN_ALERT "Unable to handle kernel paging request");
 216         printk(" at virtual addr %08lx\n", ear0);
 217         printk("  PC  : %08lx\n", __frame->pc);
 218         printk("  EXC : esr0=%08lx ear0=%08lx\n", esr0, ear0);
 219
 220         asm("lrai %1,%0,#1,#0,#0" : "=&r"(lrai) : "r"(ear0));
 221         asm("lrad %1,%0,#1,#0,#0" : "=&r"(lrad) : "r"(ear0));
 222
 223         printk(KERN_ALERT "  LRAI: %08lx\n", lrai);
 224         printk(KERN_ALERT "  LRAD: %08lx\n", lrad);
 225
 226         __break_hijack_kernel_event();
 227
 228         pge = pgd_offset(current->mm, ear0);
 229         pue = pud_offset(pge, ear0);
 230         _pme = pue->pue[0].ste[0];
 231
 232         printk(KERN_ALERT "  PGE : %8p { PME %08lx }\n", pge, _pme);
 233
 234         if (_pme & xAMPRx_V) {
 235                 unsigned long dampr, damlr, val;
 236
 237                 asm volatile("movsg dampr2,%0 ! movgs %2,dampr2 ! movsg damlr2,%1"
 238                              : "=&r"(dampr), "=r"(damlr)
 239                              : "r" (_pme | xAMPRx_L|xAMPRx_SS_16Kb|xAMPRx_S|xAMPRx_C|xAMPRx_V)
 240                              );
 241
 242                 pte = (pte_t *) damlr + __pte_index(ear0);
 243                 val = pte_val(*pte);
 244
 245                 asm volatile("movgs %0,dampr2" :: "r" (dampr));
 246
 247                 printk(KERN_ALERT "  PTE : %8p { %08lx }\n", pte, val);
 248         }
 249
 250         die_if_kernel("Oops\n");
 251         do_exit(SIGKILL);
 252
 253 /*
 254  * We ran out of memory, or some other thing happened to us that made
 255  * us unable to handle the page fault gracefully.
 256  */
 257  out_of_memory:
 258         up_read(&mm->mmap_sem);
 259         if (!user_mode(__frame))
 260                 goto no_context;
 261         pagefault_out_of_memory();
 262         return;
 263
 264  do_sigbus:
 265         up_read(&mm->mmap_sem);
 266
 267         /*
 268          * Send a sigbus, regardless of whether we were in kernel
 269          * or user mode.
 270          */
 271         info.si_signo = SIGBUS;
 272         info.si_errno = 0;
 273         info.si_code = BUS_ADRERR;
 274         info.si_addr = (void *) ear0;
 275         force_sig_info(SIGBUS, &info, current);
 276
 277         /* Kernel mode? Handle exceptions or die */
 278         if (!user_mode(__frame))
 279                 goto no_context;
 280         return;
 281
 282 /*
 283  * The fault was caused by a kernel PTE (such as installed by vmalloc or kmap)
 284  */
 285  kernel_pte_fault:
 286         {
 287                 /*
 288                  * Synchronize this task's top level page-table
 289                  * with the 'reference' page table.
 290                  *
 291                  * Do _not_ use "tsk" here. We might be inside
 292                  * an interrupt in the middle of a task switch..
 293                  */
 294                 int index = pgd_index(ear0);
 295                 pgd_t *pgd, *pgd_k;
 296                 pud_t *pud, *pud_k;
 297                 pmd_t *pmd, *pmd_k;
 298                 pte_t *pte_k;
 299
 300                 pgd = (pgd_t *) __get_TTBR();
 301                 pgd = (pgd_t *)__va(pgd) + index;
 302                 pgd_k = ((pgd_t *)(init_mm.pgd)) + index;
 303
 304                 if (!pgd_present(*pgd_k))
 305                         goto no_context;
 306                 //set_pgd(pgd, *pgd_k); /////// gcc ICE's on this line
 307
 308                 pud_k = pud_offset(pgd_k, ear0);
 309                 if (!pud_present(*pud_k))
 310                         goto no_context;
 311
 312                 pmd_k = pmd_offset(pud_k, ear0);
 313                 if (!pmd_present(*pmd_k))
 314                         goto no_context;
 315
 316                 pud = pud_offset(pgd, ear0);
 317                 pmd = pmd_offset(pud, ear0);
 318                 set_pmd(pmd, *pmd_k);
 319
 320                 pte_k = pte_offset_kernel(pmd_k, ear0);
 321                 if (!pte_present(*pte_k))
 322                         goto no_context;
 323                 return;
 324         }
 325 } /* end do_page_fault() */