arch/sh/mm/fault.c

   1 /*
   2  * Page fault handler for SH with an MMU.
   3  *
   4  *  Copyright (C) 1999  Niibe Yutaka
   5  *  Copyright (C) 2003  Paul Mundt
   6  *
   7  *  Based on linux/arch/i386/mm/fault.c:
   8  *   Copyright (C) 1995  Linus Torvalds
   9  *
  10  * This file is subject to the terms and conditions of the GNU General Public
  11  * License.  See the file "COPYING" in the main directory of this archive
  12  * for more details.
  13  */
  14 #include <linux/kernel.h>
  15 #include <linux/mm.h>
  16 #include <linux/hardirq.h>
  17 #include <linux/kprobes.h>
  18 #include <asm/system.h>
  19 #include <asm/mmu_context.h>
  20 #include <asm/kgdb.h>
  21
  22 extern void die(const char *,struct pt_regs *,long);
  23
  24 /*
  25  * This routine handles page faults.  It determines the address,
  26  * and the problem, and then passes it off to one of the appropriate
  27  * routines.
  28  */
  29 asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
  30                                         unsigned long writeaccess,
  31                                         unsigned long address)
  32 {
  33         struct task_struct *tsk;
  34         struct mm_struct *mm;
  35         struct vm_area_struct * vma;
  36         unsigned long page;
  37         int si_code;
  38         siginfo_t info;
  39
  40 #ifdef CONFIG_SH_KGDB
  41         if (kgdb_nofault && kgdb_bus_err_hook)
  42                 kgdb_bus_err_hook();
  43 #endif
  44
  45         tsk = current;
  46         mm = tsk->mm;
  47         si_code = SEGV_MAPERR;
  48
  49         if (unlikely(address >= TASK_SIZE)) {
  50                 /*
  51                  * Synchronize this task's top level page-table
  52                  * with the 'reference' page table.
  53                  *
  54                  * Do _not_ use "tsk" here. We might be inside
  55                  * an interrupt in the middle of a task switch..
  56                  */
  57                 int offset = pgd_index(address);
  58                 pgd_t *pgd, *pgd_k;
  59                 pud_t *pud, *pud_k;
  60                 pmd_t *pmd, *pmd_k;
  61
  62                 pgd = get_TTB() + offset;
  63                 pgd_k = swapper_pg_dir + offset;
  64
  65                 /* This will never happen with the folded page table. */
  66                 if (!pgd_present(*pgd)) {
  67                         if (!pgd_present(*pgd_k))
  68                                 goto bad_area_nosemaphore;
  69                         set_pgd(pgd, *pgd_k);
  70                         return;
  71                 }
  72
  73                 pud = pud_offset(pgd, address);
  74                 pud_k = pud_offset(pgd_k, address);
  75                 if (pud_present(*pud) || !pud_present(*pud_k))
  76                         goto bad_area_nosemaphore;
  77                 set_pud(pud, *pud_k);
  78
  79                 pmd = pmd_offset(pud, address);
  80                 pmd_k = pmd_offset(pud_k, address);
  81                 if (pmd_present(*pmd) || !pmd_present(*pmd_k))
  82                         goto bad_area_nosemaphore;
  83                 set_pmd(pmd, *pmd_k);
  84
  85                 return;
  86         }
  87
  88         /*
  89          * If we're in an interrupt or have no user
  90          * context, we must not take the fault..
  91          */
  92         if (in_atomic() || !mm)
  93                 goto no_context;
  94
  95         down_read(&mm->mmap_sem);
  96
  97         vma = find_vma(mm, address);
  98         if (!vma)
  99                 goto bad_area;
 100         if (vma->vm_start <= address)
 101                 goto good_area;
 102         if (!(vma->vm_flags & VM_GROWSDOWN))
 103                 goto bad_area;
 104         if (expand_stack(vma, address))
 105                 goto bad_area;
 106 /*
 107  * Ok, we have a good vm_area for this memory access, so
 108  * we can handle it..
 109  */
 110 good_area:
 111         si_code = SEGV_ACCERR;
 112         if (writeaccess) {
 113                 if (!(vma->vm_flags & VM_WRITE))
 114                         goto bad_area;
 115         } else {
 116                 if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
 117                         goto bad_area;
 118         }
 119
 120         /*
 121          * If for any reason at all we couldn't handle the fault,
 122          * make sure we exit gracefully rather than endlessly redo
 123          * the fault.
 124          */
 125 survive:
 126         switch (handle_mm_fault(mm, vma, address, writeaccess)) {
 127                 case VM_FAULT_MINOR:
 128                         tsk->min_flt++;
 129                         break;
 130                 case VM_FAULT_MAJOR:
 131                         tsk->maj_flt++;
 132                         break;
 133                 case VM_FAULT_SIGBUS:
 134                         goto do_sigbus;
 135                 case VM_FAULT_OOM:
 136                         goto out_of_memory;
 137                 default:
 138                         BUG();
 139         }
 140
 141         up_read(&mm->mmap_sem);
 142         return;
 143
 144 /*
 145  * Something tried to access memory that isn't in our memory map..
 146  * Fix it, but check if it's kernel or user first..
 147  */
 148 bad_area:
 149         up_read(&mm->mmap_sem);
 150
 151 bad_area_nosemaphore:
 152         if (user_mode(regs)) {
 153                 info.si_signo = SIGSEGV;
 154                 info.si_errno = 0;
 155                 info.si_code = si_code;
 156                 info.si_addr = (void *) address;
 157                 force_sig_info(SIGSEGV, &info, tsk);
 158                 return;
 159         }
 160
 161 no_context:
 162         /* Are we prepared to handle this kernel fault?  */
 163         if (fixup_exception(regs))
 164                 return;
 165
 166 /*
 167  * Oops. The kernel tried to access some bad page. We'll have to
 168  * terminate things with extreme prejudice.
 169  *
 170  */
 171         if (address < PAGE_SIZE)
 172                 printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference");
 173         else
 174                 printk(KERN_ALERT "Unable to handle kernel paging request");
 175         printk(" at virtual address %08lx\n", address);
 176         printk(KERN_ALERT "pc = %08lx\n", regs->pc);
 177         asm volatile("mov.l     %1, %0"
 178                      : "=r" (page)
 179                      : "m" (__m(MMU_TTB)));
 180         if (page) {
 181                 page = ((unsigned long *) page)[address >> 22];
 182                 printk(KERN_ALERT "*pde = %08lx\n", page);
 183                 if (page & _PAGE_PRESENT) {
 184                         page &= PAGE_MASK;
 185                         address &= 0x003ff000;
 186                         page = ((unsigned long *) __va(page))[address >> PAGE_SHIFT];
 187                         printk(KERN_ALERT "*pte = %08lx\n", page);
 188                 }
 189         }
 190         die("Oops", regs, writeaccess);
 191         do_exit(SIGKILL);
 192
 193 /*
 194  * We ran out of memory, or some other thing happened to us that made
 195  * us unable to handle the page fault gracefully.
 196  */
 197 out_of_memory:
 198         up_read(&mm->mmap_sem);
 199         if (is_init(current)) {
 200                 yield();
 201                 down_read(&mm->mmap_sem);
 202                 goto survive;
 203         }
 204         printk("VM: killing process %s\n", tsk->comm);
 205         if (user_mode(regs))
 206                 do_exit(SIGKILL);
 207         goto no_context;
 208
 209 do_sigbus:
 210         up_read(&mm->mmap_sem);
 211
 212         /*
 213          * Send a sigbus, regardless of whether we were in kernel
 214          * or user mode.
 215          */
 216         info.si_signo = SIGBUS;
 217         info.si_errno = 0;
 218         info.si_code = BUS_ADRERR;
 219         info.si_addr = (void *)address;
 220         force_sig_info(SIGBUS, &info, tsk);
 221
 222         /* Kernel mode? Handle exceptions or die */
 223         if (!user_mode(regs))
 224                 goto no_context;
 225 }
 226
 227 #ifdef CONFIG_SH_STORE_QUEUES
 228 /*
 229  * This is a special case for the SH-4 store queues, as pages for this
 230  * space still need to be faulted in before it's possible to flush the
 231  * store queue cache for writeout to the remapped region.
 232  */
 233 #define P3_ADDR_MAX             (P4SEG_STORE_QUE + 0x04000000)
 234 #else
 235 #define P3_ADDR_MAX             P4SEG
 236 #endif
 237
 238 /*
 239  * Called with interrupts disabled.
 240  */
 241 asmlinkage int __kprobes __do_page_fault(struct pt_regs *regs,
 242                                          unsigned long writeaccess,
 243                                          unsigned long address)
 244 {
 245         pgd_t *pgd;
 246         pud_t *pud;
 247         pmd_t *pmd;
 248         pte_t *pte;
 249         pte_t entry;
 250         struct mm_struct *mm = current->mm;
 251         spinlock_t *ptl;
 252         int ret = 1;
 253
 254 #ifdef CONFIG_SH_KGDB
 255         if (kgdb_nofault && kgdb_bus_err_hook)
 256                 kgdb_bus_err_hook();
 257 #endif
 258
 259         /*
 260          * We don't take page faults for P1, P2, and parts of P4, these
 261          * are always mapped, whether it be due to legacy behaviour in
 262          * 29-bit mode, or due to PMB configuration in 32-bit mode.
 263          */
 264         if (address >= P3SEG && address < P3_ADDR_MAX) {
 265                 pgd = pgd_offset_k(address);
 266                 mm = NULL;
 267         } else {
 268                 if (unlikely(address >= TASK_SIZE || !mm))
 269                         return 1;
 270
 271                 pgd = pgd_offset(mm, address);
 272         }
 273
 274         pud = pud_offset(pgd, address);
 275         if (pud_none_or_clear_bad(pud))
 276                 return 1;
 277         pmd = pmd_offset(pud, address);
 278         if (pmd_none_or_clear_bad(pmd))
 279                 return 1;
 280
 281         if (mm)
 282                 pte = pte_offset_map_lock(mm, pmd, address, &ptl);
 283         else
 284                 pte = pte_offset_kernel(pmd, address);
 285
 286         entry = *pte;
 287         if (unlikely(pte_none(entry) || pte_not_present(entry)))
 288                 goto unlock;
 289         if (unlikely(writeaccess && !pte_write(entry)))
 290                 goto unlock;
 291
 292         if (writeaccess)
 293                 entry = pte_mkdirty(entry);
 294         entry = pte_mkyoung(entry);
 295
 296 #ifdef CONFIG_CPU_SH4
 297         /*
 298          * ITLB is not affected by "ldtlb" instruction.
 299          * So, we need to flush the entry by ourselves.
 300          */
 301         __flush_tlb_page(get_asid(), address & PAGE_MASK);
 302 #endif
 303
 304         set_pte(pte, entry);
 305         update_mmu_cache(NULL, address, entry);
 306         ret = 0;
 307 unlock:
 308         if (mm)
 309                 pte_unmap_unlock(pte, ptl);
 310         return ret;
 311 }