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