LXR linux/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 */
  33asmlinkage 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() */
 327