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 #include <linux/uaccess.h>
  38
  39 /*
  40  * This routine handles page faults.  It determines the address,
  41  * and the problem, and then passes it off to one of the appropriate
  42  * routines.
  43  */
  44 asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long write,
  45                                 unsigned long address)
  46 {
  47         struct vm_area_struct *vma = NULL;
  48         struct task_struct *tsk = current;
  49         struct mm_struct *mm = tsk->mm;
  50         const int field = sizeof(unsigned long) * 2;
  51         unsigned long flags = 0;
  52         siginfo_t info;
  53         int fault;
  54
  55         info.si_code = SEGV_MAPERR;
  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         if (unlikely(address >= VMALLOC_START && address <= VMALLOC_END))
  67                 goto vmalloc_fault;
  68 #ifdef MODULE_START
  69         if (unlikely(address >= MODULE_START && address < MODULE_END))
  70                 goto vmalloc_fault;
  71 #endif
  72
  73         /*
  74         * If we're in an interrupt or have no user
  75         * context, we must not take the fault..
  76         */
  77         if (pagefault_disabled() || !mm)
  78                 goto bad_area_nosemaphore;
  79
  80         if (user_mode(regs))
  81                 flags |= FAULT_FLAG_USER;
  82
  83         down_read(&mm->mmap_sem);
  84         vma = find_vma(mm, address);
  85         if (!vma)
  86                 goto bad_area;
  87         if (vma->vm_start <= address)
  88                 goto good_area;
  89         if (!(vma->vm_flags & VM_GROWSDOWN))
  90                 goto bad_area;
  91         if (expand_stack(vma, address))
  92                 goto bad_area;
  93         /*
  94         * Ok, we have a good vm_area for this memory access, so
  95         * we can handle it..
  96          */
  97 good_area:
  98         info.si_code = SEGV_ACCERR;
  99
 100         if (write) {
 101                 if (!(vma->vm_flags & VM_WRITE))
 102                         goto bad_area;
 103                 flags |= FAULT_FLAG_WRITE;
 104         } else {
 105                 if (!(vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC)))
 106                         goto bad_area;
 107         }
 108
 109         /*
 110         * If for any reason at all we couldn't handle the fault,
 111         * make sure we exit gracefully rather than endlessly redo
 112         * the fault.
 113         */
 114         fault = handle_mm_fault(mm, vma, address, flags);
 115         if (unlikely(fault & VM_FAULT_ERROR)) {
 116                 if (fault & VM_FAULT_OOM)
 117                         goto out_of_memory;
 118                 else if (fault & VM_FAULT_SIGSEGV)
 119                         goto bad_area;
 120                 else if (fault & VM_FAULT_SIGBUS)
 121                         goto do_sigbus;
 122                 BUG();
 123         }
 124         if (fault & VM_FAULT_MAJOR)
 125                 tsk->maj_flt++;
 126         else
 127                 tsk->min_flt++;
 128
 129         up_read(&mm->mmap_sem);
 130         return;
 131
 132         /*
 133         * Something tried to access memory that isn't in our memory map..
 134         * Fix it, but check if it's kernel or user first..
 135          */
 136 bad_area:
 137         up_read(&mm->mmap_sem);
 138
 139 bad_area_nosemaphore:
 140         /* User mode accesses just cause a SIGSEGV */
 141         if (user_mode(regs)) {
 142                 tsk->thread.cp0_badvaddr = address;
 143                 tsk->thread.error_code = write;
 144                 info.si_signo = SIGSEGV;
 145                 info.si_errno = 0;
 146                 /* info.si_code has been set above */
 147                 info.si_addr = (void __user *) address;
 148                 force_sig_info(SIGSEGV, &info, tsk);
 149                 return;
 150         }
 151
 152 no_context:
 153         /* Are we prepared to handle this kernel fault? */
 154         if (fixup_exception(regs)) {
 155                 current->thread.cp0_baduaddr = address;
 156                 return;
 157         }
 158
 159         /*
 160         * Oops. The kernel tried to access some bad page. We'll have to
 161         * terminate things with extreme prejudice.
 162         */
 163         bust_spinlocks(1);
 164
 165         printk(KERN_ALERT "CPU %d Unable to handle kernel paging request at "
 166                         "virtual address %0*lx, epc == %0*lx, ra == %0*lx\n",
 167                         0, field, address, field, regs->cp0_epc,
 168                         field, regs->regs[3]);
 169         die("Oops", regs);
 170
 171         /*
 172         * We ran out of memory, or some other thing happened to us that made
 173         * us unable to handle the page fault gracefully.
 174         */
 175 out_of_memory:
 176         up_read(&mm->mmap_sem);
 177         if (!user_mode(regs))
 178                 goto no_context;
 179         pagefault_out_of_memory();
 180         return;
 181
 182 do_sigbus:
 183         up_read(&mm->mmap_sem);
 184         /* Kernel mode? Handle exceptions or die */
 185         if (!user_mode(regs))
 186                 goto no_context;
 187         else
 188         /*
 189         * Send a sigbus, regardless of whether we were in kernel
 190         * or user mode.
 191         */
 192         tsk->thread.cp0_badvaddr = address;
 193         info.si_signo = SIGBUS;
 194         info.si_errno = 0;
 195         info.si_code = BUS_ADRERR;
 196         info.si_addr = (void __user *) address;
 197         force_sig_info(SIGBUS, &info, tsk);
 198         return;
 199 vmalloc_fault:
 200         {
 201                 /*
 202                 * Synchronize this task's top level page-table
 203                 * with the 'reference' page table.
 204                 *
 205                 * Do _not_ use "tsk" here. We might be inside
 206                 * an interrupt in the middle of a task switch..
 207                 */
 208                 int offset = __pgd_offset(address);
 209                 pgd_t *pgd, *pgd_k;
 210                 pud_t *pud, *pud_k;
 211                 pmd_t *pmd, *pmd_k;
 212                 pte_t *pte_k;
 213
 214                 pgd = (pgd_t *) pgd_current + offset;
 215                 pgd_k = init_mm.pgd + offset;
 216
 217                 if (!pgd_present(*pgd_k))
 218                         goto no_context;
 219                 set_pgd(pgd, *pgd_k);
 220
 221                 pud = pud_offset(pgd, address);
 222                 pud_k = pud_offset(pgd_k, address);
 223                 if (!pud_present(*pud_k))
 224                         goto no_context;
 225
 226                 pmd = pmd_offset(pud, address);
 227                 pmd_k = pmd_offset(pud_k, address);
 228                 if (!pmd_present(*pmd_k))
 229                         goto no_context;
 230                 set_pmd(pmd, *pmd_k);
 231
 232                 pte_k = pte_offset_kernel(pmd_k, address);
 233                 if (!pte_present(*pte_k))
 234                         goto no_context;
 235                 return;
 236         }
 237 }