git.oblomov.eu Git - linux-2.6/blob - arch/sh/mm/fault_32.c

   1 /*
   2  * Page fault handler for SH with an MMU.
   3  *
   4  *  Copyright (C) 1999  Niibe Yutaka
   5  *  Copyright (C) 2003 - 2007  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/io_trapped.h>
  19 #include <asm/system.h>
  20 #include <asm/mmu_context.h>
  21 #include <asm/tlbflush.h>
  22 #include <asm/kgdb.h>
  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         int si_code;
  37         int fault;
  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         si_code = SEGV_MAPERR;
  47
  48         if (unlikely(address >= TASK_SIZE)) {
  49                 /*
  50                  * Synchronize this task's top level page-table
  51                  * with the 'reference' page table.
  52                  *
  53                  * Do _not_ use "tsk" here. We might be inside
  54                  * an interrupt in the middle of a task switch..
  55                  */
  56                 int offset = pgd_index(address);
  57                 pgd_t *pgd, *pgd_k;
  58                 pud_t *pud, *pud_k;
  59                 pmd_t *pmd, *pmd_k;
  60
  61                 pgd = get_TTB() + offset;
  62                 pgd_k = swapper_pg_dir + offset;
  63
  64                 /* This will never happen with the folded page table. */
  65                 if (!pgd_present(*pgd)) {
  66                         if (!pgd_present(*pgd_k))
  67                                 goto bad_area_nosemaphore;
  68                         set_pgd(pgd, *pgd_k);
  69                         return;
  70                 }
  71
  72                 pud = pud_offset(pgd, address);
  73                 pud_k = pud_offset(pgd_k, address);
  74                 if (pud_present(*pud) || !pud_present(*pud_k))
  75                         goto bad_area_nosemaphore;
  76                 set_pud(pud, *pud_k);
  77
  78                 pmd = pmd_offset(pud, address);
  79                 pmd_k = pmd_offset(pud_k, address);
  80                 if (pmd_present(*pmd) || !pmd_present(*pmd_k))
  81                         goto bad_area_nosemaphore;
  82                 set_pmd(pmd, *pmd_k);
  83
  84                 return;
  85         }
  86
  87         /* Only enable interrupts if they were on before the fault */
  88         if ((regs->sr & SR_IMASK) != SR_IMASK) {
  89                 trace_hardirqs_on();
  90                 local_irq_enable();
  91         }
  92
  93         mm = tsk->mm;
  94
  95         /*
  96          * If we're in an interrupt or have no user
  97          * context, we must not take the fault..
  98          */
  99         if (in_atomic() || !mm)
 100                 goto no_context;
 101
 102         down_read(&mm->mmap_sem);
 103
 104         vma = find_vma(mm, address);
 105         if (!vma)
 106                 goto bad_area;
 107         if (vma->vm_start <= address)
 108                 goto good_area;
 109         if (!(vma->vm_flags & VM_GROWSDOWN))
 110                 goto bad_area;
 111         if (expand_stack(vma, address))
 112                 goto bad_area;
 113 /*
 114  * Ok, we have a good vm_area for this memory access, so
 115  * we can handle it..
 116  */
 117 good_area:
 118         si_code = SEGV_ACCERR;
 119         if (writeaccess) {
 120                 if (!(vma->vm_flags & VM_WRITE))
 121                         goto bad_area;
 122         } else {
 123                 if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
 124                         goto bad_area;
 125         }
 126
 127         /*
 128          * If for any reason at all we couldn't handle the fault,
 129          * make sure we exit gracefully rather than endlessly redo
 130          * the fault.
 131          */
 132 survive:
 133         fault = handle_mm_fault(mm, vma, address, writeaccess);
 134         if (unlikely(fault & VM_FAULT_ERROR)) {
 135                 if (fault & VM_FAULT_OOM)
 136                         goto out_of_memory;
 137                 else if (fault & VM_FAULT_SIGBUS)
 138                         goto do_sigbus;
 139                 BUG();
 140         }
 141         if (fault & VM_FAULT_MAJOR)
 142                 tsk->maj_flt++;
 143         else
 144                 tsk->min_flt++;
 145
 146         up_read(&mm->mmap_sem);
 147         return;
 148
 149 /*
 150  * Something tried to access memory that isn't in our memory map..
 151  * Fix it, but check if it's kernel or user first..
 152  */
 153 bad_area:
 154         up_read(&mm->mmap_sem);
 155
 156 bad_area_nosemaphore:
 157         if (user_mode(regs)) {
 158                 info.si_signo = SIGSEGV;
 159                 info.si_errno = 0;
 160                 info.si_code = si_code;
 161                 info.si_addr = (void *) address;
 162                 force_sig_info(SIGSEGV, &info, tsk);
 163                 return;
 164         }
 165
 166 no_context:
 167         /* Are we prepared to handle this kernel fault?  */
 168         if (fixup_exception(regs))
 169                 return;
 170
 171         if (handle_trapped_io(regs, address))
 172                 return;
 173 /*
 174  * Oops. The kernel tried to access some bad page. We'll have to
 175  * terminate things with extreme prejudice.
 176  *
 177  */
 178
 179         bust_spinlocks(1);
 180
 181         if (oops_may_print()) {
 182                 unsigned long page;
 183
 184                 if (address < PAGE_SIZE)
 185                         printk(KERN_ALERT "Unable to handle kernel NULL "
 186                                           "pointer dereference");
 187                 else
 188                         printk(KERN_ALERT "Unable to handle kernel paging "
 189                                           "request");
 190                 printk(" at virtual address %08lx\n", address);
 191                 printk(KERN_ALERT "pc = %08lx\n", regs->pc);
 192                 page = (unsigned long)get_TTB();
 193                 if (page) {
 194                         page = ((__typeof__(page) *)page)[address >> PGDIR_SHIFT];
 195                         printk(KERN_ALERT "*pde = %08lx\n", page);
 196                         if (page & _PAGE_PRESENT) {
 197                                 page &= PAGE_MASK;
 198                                 address &= 0x003ff000;
 199                                 page = ((__typeof__(page) *)
 200                                                 __va(page))[address >>
 201                                                             PAGE_SHIFT];
 202                                 printk(KERN_ALERT "*pte = %08lx\n", page);
 203                         }
 204                 }
 205         }
 206
 207         die("Oops", regs, writeaccess);
 208         bust_spinlocks(0);
 209         do_exit(SIGKILL);
 210
 211 /*
 212  * We ran out of memory, or some other thing happened to us that made
 213  * us unable to handle the page fault gracefully.
 214  */
 215 out_of_memory:
 216         up_read(&mm->mmap_sem);
 217         if (is_global_init(current)) {
 218                 yield();
 219                 down_read(&mm->mmap_sem);
 220                 goto survive;
 221         }
 222         printk("VM: killing process %s\n", tsk->comm);
 223         if (user_mode(regs))
 224                 do_group_exit(SIGKILL);
 225         goto no_context;
 226
 227 do_sigbus:
 228         up_read(&mm->mmap_sem);
 229
 230         /*
 231          * Send a sigbus, regardless of whether we were in kernel
 232          * or user mode.
 233          */
 234         info.si_signo = SIGBUS;
 235         info.si_errno = 0;
 236         info.si_code = BUS_ADRERR;
 237         info.si_addr = (void *)address;
 238         force_sig_info(SIGBUS, &info, tsk);
 239
 240         /* Kernel mode? Handle exceptions or die */
 241         if (!user_mode(regs))
 242                 goto no_context;
 243 }
 244
 245 #ifdef CONFIG_SH_STORE_QUEUES
 246 /*
 247  * This is a special case for the SH-4 store queues, as pages for this
 248  * space still need to be faulted in before it's possible to flush the
 249  * store queue cache for writeout to the remapped region.
 250  */
 251 #define P3_ADDR_MAX             (P4SEG_STORE_QUE + 0x04000000)
 252 #else
 253 #define P3_ADDR_MAX             P4SEG
 254 #endif
 255
 256 /*
 257  * Called with interrupts disabled.
 258  */
 259 asmlinkage int __kprobes __do_page_fault(struct pt_regs *regs,
 260                                          unsigned long writeaccess,
 261                                          unsigned long address)
 262 {
 263         pgd_t *pgd;
 264         pud_t *pud;
 265         pmd_t *pmd;
 266         pte_t *pte;
 267         pte_t entry;
 268
 269 #ifdef CONFIG_SH_KGDB
 270         if (kgdb_nofault && kgdb_bus_err_hook)
 271                 kgdb_bus_err_hook();
 272 #endif
 273
 274         /*
 275          * We don't take page faults for P1, P2, and parts of P4, these
 276          * are always mapped, whether it be due to legacy behaviour in
 277          * 29-bit mode, or due to PMB configuration in 32-bit mode.
 278          */
 279         if (address >= P3SEG && address < P3_ADDR_MAX) {
 280                 pgd = pgd_offset_k(address);
 281         } else {
 282                 if (unlikely(address >= TASK_SIZE || !current->mm))
 283                         return 1;
 284
 285                 pgd = pgd_offset(current->mm, address);
 286         }
 287
 288         pud = pud_offset(pgd, address);
 289         if (pud_none_or_clear_bad(pud))
 290                 return 1;
 291         pmd = pmd_offset(pud, address);
 292         if (pmd_none_or_clear_bad(pmd))
 293                 return 1;
 294
 295         pte = pte_offset_kernel(pmd, address);
 296         entry = *pte;
 297         if (unlikely(pte_none(entry) || pte_not_present(entry)))
 298                 return 1;
 299         if (unlikely(writeaccess && !pte_write(entry)))
 300                 return 1;
 301
 302         if (writeaccess)
 303                 entry = pte_mkdirty(entry);
 304         entry = pte_mkyoung(entry);
 305
 306 #if defined(CONFIG_CPU_SH4) && !defined(CONFIG_SMP)
 307         /*
 308          * ITLB is not affected by "ldtlb" instruction.
 309          * So, we need to flush the entry by ourselves.
 310          */
 311         local_flush_tlb_one(get_asid(), address & PAGE_MASK);
 312 #endif
 313
 314         set_pte(pte, entry);
 315         update_mmu_cache(NULL, address, entry);
 316
 317         return 0;
 318 }