release/src-rt-6.x/linux/linux-2.6/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 - 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/system.h>
  19 #include <asm/mmu_context.h>
  20 #include <asm/tlbflush.h>
  21 #include <asm/kgdb.h>
  22
  23 /*
  24  * This routine handles page faults.  It determines the address,
  25  * and the problem, and then passes it off to one of the appropriate
  26  * routines.
  27  */
  28 asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
  29                                         unsigned long writeaccess,
  30                                         unsigned long address)
  31 {
  32         struct task_struct *tsk;
  33         struct mm_struct *mm;
  34         struct vm_area_struct * vma;
  35         unsigned long page;
  36         int si_code;
  37         int fault;
  38         siginfo_t info;
  39
  40         trace_hardirqs_on();
  41         local_irq_enable();
  42
  43 #ifdef CONFIG_SH_KGDB
  44         if (kgdb_nofault && kgdb_bus_err_hook)
  45                 kgdb_bus_err_hook();
  46 #endif
  47
  48         tsk = current;
  49         mm = tsk->mm;
  50         si_code = SEGV_MAPERR;
  51
  52         if (unlikely(address >= TASK_SIZE)) {
  53                 /*
  54                  * Synchronize this task's top level page-table
  55                  * with the 'reference' page table.
  56                  *
  57                  * Do _not_ use "tsk" here. We might be inside
  58                  * an interrupt in the middle of a task switch..
  59                  */
  60                 int offset = pgd_index(address);
  61                 pgd_t *pgd, *pgd_k;
  62                 pud_t *pud, *pud_k;
  63                 pmd_t *pmd, *pmd_k;
  64
  65                 pgd = get_TTB() + offset;
  66                 pgd_k = swapper_pg_dir + offset;
  67
  68                 /* This will never happen with the folded page table. */
  69                 if (!pgd_present(*pgd)) {
  70                         if (!pgd_present(*pgd_k))
  71                                 goto bad_area_nosemaphore;
  72                         set_pgd(pgd, *pgd_k);
  73                         return;
  74                 }
  75
  76                 pud = pud_offset(pgd, address);
  77                 pud_k = pud_offset(pgd_k, address);
  78                 if (pud_present(*pud) || !pud_present(*pud_k))
  79                         goto bad_area_nosemaphore;
  80                 set_pud(pud, *pud_k);
  81
  82                 pmd = pmd_offset(pud, address);
  83                 pmd_k = pmd_offset(pud_k, address);
  84                 if (pmd_present(*pmd) || !pmd_present(*pmd_k))
  85                         goto bad_area_nosemaphore;
  86                 set_pmd(pmd, *pmd_k);
  87
  88                 return;
  89         }
  90
  91         /*
  92          * If we're in an interrupt or have no user
  93          * context, we must not take the fault..
  94          */
  95         if (in_atomic() || !mm)
  96                 goto no_context;
  97
  98         down_read(&mm->mmap_sem);
  99
 100         vma = find_vma(mm, address);
 101         if (!vma)
 102                 goto bad_area;
 103         if (vma->vm_start <= address)
 104                 goto good_area;
 105         if (!(vma->vm_flags & VM_GROWSDOWN))
 106                 goto bad_area;
 107         if (expand_stack(vma, address))
 108                 goto bad_area;
 109 /*
 110  * Ok, we have a good vm_area for this memory access, so
 111  * we can handle it..
 112  */
 113 good_area:
 114         si_code = SEGV_ACCERR;
 115         if (writeaccess) {
 116                 if (!(vma->vm_flags & VM_WRITE))
 117                         goto bad_area;
 118         } else {
 119                 if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
 120                         goto bad_area;
 121         }
 122
 123         /*
 124          * If for any reason at all we couldn't handle the fault,
 125          * make sure we exit gracefully rather than endlessly redo
 126          * the fault.
 127          */
 128 survive:
 129         fault = handle_mm_fault(mm, vma, address, writeaccess);
 130         if (unlikely(fault & VM_FAULT_ERROR)) {
 131                 if (fault & VM_FAULT_OOM)
 132                         goto out_of_memory;
 133                 else if (fault & VM_FAULT_SIGBUS)
 134                         goto do_sigbus;
 135                 BUG();
 136         }
 137         if (fault & VM_FAULT_MAJOR)
 138                 tsk->maj_flt++;
 139         else
 140                 tsk->min_flt++;
 141
 142         up_read(&mm->mmap_sem);
 143         return;
 144
 145 /*
 146  * Something tried to access memory that isn't in our memory map..
 147  * Fix it, but check if it's kernel or user first..
 148  */
 149 bad_area:
 150         up_read(&mm->mmap_sem);
 151
 152 bad_area_nosemaphore:
 153         if (user_mode(regs)) {
 154                 info.si_signo = SIGSEGV;
 155                 info.si_errno = 0;
 156                 info.si_code = si_code;
 157                 info.si_addr = (void *) address;
 158                 force_sig_info(SIGSEGV, &info, tsk);
 159                 return;
 160         }
 161
 162 no_context:
 163         /* Are we prepared to handle this kernel fault?  */
 164         if (fixup_exception(regs))
 165                 return;
 166
 167 /*
 168  * Oops. The kernel tried to access some bad page. We'll have to
 169  * terminate things with extreme prejudice.
 170  *
 171  */
 172         if (address < PAGE_SIZE)
 173                 printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference");
 174         else
 175                 printk(KERN_ALERT "Unable to handle kernel paging request");
 176         printk(" at virtual address %08lx\n", address);
 177         printk(KERN_ALERT "pc = %08lx\n", regs->pc);
 178         page = (unsigned long)get_TTB();
 179         if (page) {
 180                 page = ((unsigned long *) page)[address >> PGDIR_SHIFT];
 181                 printk(KERN_ALERT "*pde = %08lx\n", page);
 182                 if (page & _PAGE_PRESENT) {
 183                         page &= PAGE_MASK;
 184                         address &= 0x003ff000;
 185                         page = ((unsigned long *) __va(page))[address >> PAGE_SHIFT];
 186                         printk(KERN_ALERT "*pte = %08lx\n", page);
 187                 }
 188         }
 189         die("Oops", regs, writeaccess);
 190         do_exit(SIGKILL);
 191
 192 /*
 193  * We ran out of memory, or some other thing happened to us that made
 194  * us unable to handle the page fault gracefully.
 195  */
 196 out_of_memory:
 197         up_read(&mm->mmap_sem);
 198         if (is_init(current)) {
 199                 yield();
 200                 down_read(&mm->mmap_sem);
 201                 goto survive;
 202         }
 203         printk("VM: killing process %s\n", tsk->comm);
 204         if (user_mode(regs))
 205                 do_exit(SIGKILL);
 206         goto no_context;
 207
 208 do_sigbus:
 209         up_read(&mm->mmap_sem);
 210
 211         /*
 212          * Send a sigbus, regardless of whether we were in kernel
 213          * or user mode.
 214          */
 215         info.si_signo = SIGBUS;
 216         info.si_errno = 0;
 217         info.si_code = BUS_ADRERR;
 218         info.si_addr = (void *)address;
 219         force_sig_info(SIGBUS, &info, tsk);
 220
 221         /* Kernel mode? Handle exceptions or die */
 222         if (!user_mode(regs))
 223                 goto no_context;
 224 }
 225
 226 #ifdef CONFIG_SH_STORE_QUEUES
 227 /*
 228  * This is a special case for the SH-4 store queues, as pages for this
 229  * space still need to be faulted in before it's possible to flush the
 230  * store queue cache for writeout to the remapped region.
 231  */
 232 #define P3_ADDR_MAX             (P4SEG_STORE_QUE + 0x04000000)
 233 #else
 234 #define P3_ADDR_MAX             P4SEG
 235 #endif
 236
 237 /*
 238  * Called with interrupts disabled.
 239  */
 240 asmlinkage int __kprobes __do_page_fault(struct pt_regs *regs,
 241                                          unsigned long writeaccess,
 242                                          unsigned long address)
 243 {
 244         pgd_t *pgd;
 245         pud_t *pud;
 246         pmd_t *pmd;
 247         pte_t *pte;
 248         pte_t entry;
 249         struct mm_struct *mm = current->mm;
 250         spinlock_t *ptl = NULL;
 251         int ret = 1;
 252
 253 #ifdef CONFIG_SH_KGDB
 254         if (kgdb_nofault && kgdb_bus_err_hook)
 255                 kgdb_bus_err_hook();
 256 #endif
 257
 258         /*
 259          * We don't take page faults for P1, P2, and parts of P4, these
 260          * are always mapped, whether it be due to legacy behaviour in
 261          * 29-bit mode, or due to PMB configuration in 32-bit mode.
 262          */
 263         if (address >= P3SEG && address < P3_ADDR_MAX) {
 264                 pgd = pgd_offset_k(address);
 265                 mm = NULL;
 266         } else {
 267                 if (unlikely(address >= TASK_SIZE || !mm))
 268                         return 1;
 269
 270                 pgd = pgd_offset(mm, address);
 271         }
 272
 273         pud = pud_offset(pgd, address);
 274         if (pud_none_or_clear_bad(pud))
 275                 return 1;
 276         pmd = pmd_offset(pud, address);
 277         if (pmd_none_or_clear_bad(pmd))
 278                 return 1;
 279
 280         if (mm)
 281                 pte = pte_offset_map_lock(mm, pmd, address, &ptl);
 282         else
 283                 pte = pte_offset_kernel(pmd, address);
 284
 285         entry = *pte;
 286         if (unlikely(pte_none(entry) || pte_not_present(entry)))
 287                 goto unlock;
 288         if (unlikely(writeaccess && !pte_write(entry)))
 289                 goto unlock;
 290
 291         if (writeaccess)
 292                 entry = pte_mkdirty(entry);
 293         entry = pte_mkyoung(entry);
 294
 295 #ifdef CONFIG_CPU_SH4
 296         /*
 297          * ITLB is not affected by "ldtlb" instruction.
 298          * So, we need to flush the entry by ourselves.
 299          */
 300         local_flush_tlb_one(get_asid(), address & PAGE_MASK);
 301 #endif
 302
 303         set_pte(pte, entry);
 304         update_mmu_cache(NULL, address, entry);
 305         ret = 0;
 306 unlock:
 307         if (mm)
 308                 pte_unmap_unlock(pte, ptl);
 309         return ret;
 310 }