arch/score/mm/fault.c

   1 /*
   2  * arch/score/mm/fault.c
   3  *
   4  * Score Processor version.
   5  *
   6  * Copyright (C) 2009 Sunplus Core Technology Co., Ltd.
   7  *  Lennox Wu <lennox.wu@sunplusct.com>
   8  *  Chen Liqin <liqin.chen@sunplusct.com>
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License as published by
  12  * the Free Software Foundation; either version 2 of the License, or
  13  * (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18  * GNU General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public License
  21  * along with this program; if not, see the file COPYING, or write
  22  * to the Free Software Foundation, Inc.,
  23  * 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  24  */
  25
  26 #include <linux/errno.h>
  27 #include <linux/interrupt.h>
  28 #include <linux/kernel.h>
  29 #include <linux/mm.h>
  30 #include <linux/mman.h>
  31 #include <linux/module.h>
  32 #include <linux/signal.h>
  33 #include <linux/sched.h>
  34 #include <linux/string.h>
  35 #include <linux/types.h>
  36 #include <linux/ptrace.h>
  37
  38 /*
  39  * This routine handles page faults.  It determines the address,
  40  * and the problem, and then passes it off to one of the appropriate
  41  * routines.
  42  */
  43 asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long write,
  44                                 unsigned long address)
  45 {
  46         struct vm_area_struct *vma = NULL;
  47         struct task_struct *tsk = current;
  48         struct mm_struct *mm = tsk->mm;
  49         const int field = sizeof(unsigned long) * 2;
  50         siginfo_t info;
  51         int fault;
  52
  53         info.si_code = SEGV_MAPERR;
  54
  55         /*
  56         * We fault-in kernel-space virtual memory on-demand. The
  57         * 'reference' page table is init_mm.pgd.
  58         *
  59         * NOTE! We MUST NOT take any locks for this case. We may
  60         * be in an interrupt or a critical region, and should
  61         * only copy the information from the master page table,
  62         * nothing more.
  63         */
  64         if (unlikely(address >= VMALLOC_START && address <= VMALLOC_END))
  65                 goto vmalloc_fault;
  66 #ifdef MODULE_START
  67         if (unlikely(address >= MODULE_START && address < MODULE_END))
  68                 goto vmalloc_fault;
  69 #endif
  70
  71         /*
  72         * If we're in an interrupt or have no user
  73         * context, we must not take the fault..
  74         */
  75         if (in_atomic() || !mm)
  76                 goto bad_area_nosemaphore;
  77
  78         down_read(&mm->mmap_sem);
  79         vma = find_vma(mm, address);
  80         if (!vma)
  81                 goto bad_area;
  82         if (vma->vm_start <= address)
  83                 goto good_area;
  84         if (!(vma->vm_flags & VM_GROWSDOWN))
  85                 goto bad_area;
  86         if (expand_stack(vma, address))
  87                 goto bad_area;
  88         /*
  89         * Ok, we have a good vm_area for this memory access, so
  90         * we can handle it..
  91          */
  92 good_area:
  93         info.si_code = SEGV_ACCERR;
  94
  95         if (write) {
  96                 if (!(vma->vm_flags & VM_WRITE))
  97                         goto bad_area;
  98         } else {
  99                 if (!(vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC)))
 100                         goto bad_area;
 101         }
 102
 103 survive:
 104         /*
 105         * If for any reason at all we couldn't handle the fault,
 106         * make sure we exit gracefully rather than endlessly redo
 107         * the fault.
 108         */
 109         fault = handle_mm_fault(mm, vma, address, write);
 110         if (unlikely(fault & VM_FAULT_ERROR)) {
 111                 if (fault & VM_FAULT_OOM)
 112                         goto out_of_memory;
 113                 else if (fault & VM_FAULT_SIGBUS)
 114                         goto do_sigbus;
 115                 BUG();
 116         }
 117         if (fault & VM_FAULT_MAJOR)
 118                 tsk->maj_flt++;
 119         else
 120                 tsk->min_flt++;
 121
 122         up_read(&mm->mmap_sem);
 123         return;
 124
 125         /*
 126         * Something tried to access memory that isn't in our memory map..
 127         * Fix it, but check if it's kernel or user first..
 128          */
 129 bad_area:
 130         up_read(&mm->mmap_sem);
 131
 132 bad_area_nosemaphore:
 133         /* User mode accesses just cause a SIGSEGV */
 134         if (user_mode(regs)) {
 135                 tsk->thread.cp0_badvaddr = address;
 136                 tsk->thread.error_code = write;
 137                 info.si_signo = SIGSEGV;
 138                 info.si_errno = 0;
 139                 /* info.si_code has been set above */
 140                 info.si_addr = (void __user *) address;
 141                 force_sig_info(SIGSEGV, &info, tsk);
 142                 return;
 143         }
 144
 145 no_context:
 146         /* Are we prepared to handle this kernel fault? */
 147         if (fixup_exception(regs)) {
 148                 current->thread.cp0_baduaddr = address;
 149                 return;
 150         }
 151
 152         /*
 153         * Oops. The kernel tried to access some bad page. We'll have to
 154         * terminate things with extreme prejudice.
 155         */
 156         bust_spinlocks(1);
 157
 158         printk(KERN_ALERT "CPU %d Unable to handle kernel paging request at "
 159                         "virtual address %0*lx, epc == %0*lx, ra == %0*lx\n",
 160                         0, field, address, field, regs->cp0_epc,
 161                         field, regs->regs[3]);
 162         die("Oops", regs);
 163
 164         /*
 165         * We ran out of memory, or some other thing happened to us that made
 166         * us unable to handle the page fault gracefully.
 167         */
 168 out_of_memory:
 169         up_read(&mm->mmap_sem);
 170         if (is_global_init(tsk)) {
 171                 yield();
 172                 down_read(&mm->mmap_sem);
 173                 goto survive;
 174         }
 175         printk("VM: killing process %s\n", tsk->comm);
 176         if (user_mode(regs))
 177                 do_group_exit(SIGKILL);
 178         goto no_context;
 179
 180 do_sigbus:
 181         up_read(&mm->mmap_sem);
 182         /* Kernel mode? Handle exceptions or die */
 183         if (!user_mode(regs))
 184                 goto no_context;
 185         else
 186         /*
 187         * Send a sigbus, regardless of whether we were in kernel
 188         * or user mode.
 189         */
 190         tsk->thread.cp0_badvaddr = address;
 191         info.si_signo = SIGBUS;
 192         info.si_errno = 0;
 193         info.si_code = BUS_ADRERR;
 194         info.si_addr = (void __user *) address;
 195         force_sig_info(SIGBUS, &info, tsk);
 196         return;
 197 vmalloc_fault:
 198         {
 199                 /*
 200                 * Synchronize this task's top level page-table
 201                 * with the 'reference' page table.
 202                 *
 203                 * Do _not_ use "tsk" here. We might be inside
 204                 * an interrupt in the middle of a task switch..
 205                 */
 206                 int offset = __pgd_offset(address);
 207                 pgd_t *pgd, *pgd_k;
 208                 pud_t *pud, *pud_k;
 209                 pmd_t *pmd, *pmd_k;
 210                 pte_t *pte_k;
 211
 212                 pgd = (pgd_t *) pgd_current + offset;
 213                 pgd_k = init_mm.pgd + offset;
 214
 215                 if (!pgd_present(*pgd_k))
 216                         goto no_context;
 217                 set_pgd(pgd, *pgd_k);
 218
 219                 pud = pud_offset(pgd, address);
 220                 pud_k = pud_offset(pgd_k, address);
 221                 if (!pud_present(*pud_k))
 222                         goto no_context;
 223
 224                 pmd = pmd_offset(pud, address);
 225                 pmd_k = pmd_offset(pud_k, address);
 226                 if (!pmd_present(*pmd_k))
 227                         goto no_context;
 228                 set_pmd(pmd, *pmd_k);
 229
 230                 pte_k = pte_offset_kernel(pmd_k, address);
 231                 if (!pte_present(*pte_k))
 232                         goto no_context;
 233                 return;
 234         }
 235 }