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         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         if (handle_trapped_io(regs, address))
 168                 return;
 169 /*
 170  * Oops. The kernel tried to access some bad page. We'll have to
 171  * terminate things with extreme prejudice.
 172  *
 173  */
 174
 175         bust_spinlocks(1);
 176
 177         if (oops_may_print()) {
 178                 unsigned long page;
 179
 180                 if (address < PAGE_SIZE)
 181                         printk(KERN_ALERT "Unable to handle kernel NULL "
 182                                           "pointer dereference");
 183                 else
 184                         printk(KERN_ALERT "Unable to handle kernel paging "
 185                                           "request");
 186                 printk(" at virtual address %08lx\n", address);
 187                 printk(KERN_ALERT "pc = %08lx\n", regs->pc);
 188                 page = (unsigned long)get_TTB();
 189                 if (page) {
 190                         page = ((__typeof__(page) *)page)[address >> PGDIR_SHIFT];
 191                         printk(KERN_ALERT "*pde = %08lx\n", page);
 192                         if (page & _PAGE_PRESENT) {
 193                                 page &= PAGE_MASK;
 194                                 address &= 0x003ff000;
 195                                 page = ((__typeof__(page) *)
 196                                                 __va(page))[address >>
 197                                                             PAGE_SHIFT];
 198                                 printk(KERN_ALERT "*pte = %08lx\n", page);
 199                         }
 200                 }
 201         }
 202
 203         die("Oops", regs, writeaccess);
 204         bust_spinlocks(0);
 205         do_exit(SIGKILL);
 206
 207 /*
 208  * We ran out of memory, or some other thing happened to us that made
 209  * us unable to handle the page fault gracefully.
 210  */
 211 out_of_memory:
 212         up_read(&mm->mmap_sem);
 213         if (is_global_init(current)) {
 214                 yield();
 215                 down_read(&mm->mmap_sem);
 216                 goto survive;
 217         }
 218         printk("VM: killing process %s\n", tsk->comm);
 219         if (user_mode(regs))
 220                 do_group_exit(SIGKILL);
 221         goto no_context;
 222
 223 do_sigbus:
 224         up_read(&mm->mmap_sem);
 225
 226         /*
 227          * Send a sigbus, regardless of whether we were in kernel
 228          * or user mode.
 229          */
 230         info.si_signo = SIGBUS;
 231         info.si_errno = 0;
 232         info.si_code = BUS_ADRERR;
 233         info.si_addr = (void *)address;
 234         force_sig_info(SIGBUS, &info, tsk);
 235
 236         /* Kernel mode? Handle exceptions or die */
 237         if (!user_mode(regs))
 238                 goto no_context;
 239 }
 240
 241 #ifdef CONFIG_SH_STORE_QUEUES
 242 /*
 243  * This is a special case for the SH-4 store queues, as pages for this
 244  * space still need to be faulted in before it's possible to flush the
 245  * store queue cache for writeout to the remapped region.
 246  */
 247 #define P3_ADDR_MAX             (P4SEG_STORE_QUE + 0x04000000)
 248 #else
 249 #define P3_ADDR_MAX             P4SEG
 250 #endif
 251
 252 /*
 253  * Called with interrupts disabled.
 254  */
 255 asmlinkage int __kprobes __do_page_fault(struct pt_regs *regs,
 256                                          unsigned long writeaccess,
 257                                          unsigned long address)
 258 {
 259         pgd_t *pgd;
 260         pud_t *pud;
 261         pmd_t *pmd;
 262         pte_t *pte;
 263         pte_t entry;
 264
 265 #ifdef CONFIG_SH_KGDB
 266         if (kgdb_nofault && kgdb_bus_err_hook)
 267                 kgdb_bus_err_hook();
 268 #endif
 269
 270         /*
 271          * We don't take page faults for P1, P2, and parts of P4, these
 272          * are always mapped, whether it be due to legacy behaviour in
 273          * 29-bit mode, or due to PMB configuration in 32-bit mode.
 274          */
 275         if (address >= P3SEG && address < P3_ADDR_MAX) {
 276                 pgd = pgd_offset_k(address);
 277         } else {
 278                 if (unlikely(address >= TASK_SIZE || !current->mm))
 279                         return 1;
 280
 281                 pgd = pgd_offset(current->mm, address);
 282         }
 283
 284         pud = pud_offset(pgd, address);
 285         if (pud_none_or_clear_bad(pud))
 286                 return 1;
 287         pmd = pmd_offset(pud, address);
 288         if (pmd_none_or_clear_bad(pmd))
 289                 return 1;
 290
 291         pte = pte_offset_kernel(pmd, address);
 292         entry = *pte;
 293         if (unlikely(pte_none(entry) || pte_not_present(entry)))
 294                 return 1;
 295         if (unlikely(writeaccess && !pte_write(entry)))
 296                 return 1;
 297
 298         if (writeaccess)
 299                 entry = pte_mkdirty(entry);
 300         entry = pte_mkyoung(entry);
 301
 302 #if defined(CONFIG_CPU_SH4) && !defined(CONFIG_SMP)
 303         /*
 304          * ITLB is not affected by "ldtlb" instruction.
 305          * So, we need to flush the entry by ourselves.
 306          */
 307         local_flush_tlb_one(get_asid(), address & PAGE_MASK);
 308 #endif
 309
 310         set_pte(pte, entry);
 311         update_mmu_cache(NULL, address, entry);
 312
 313         return 0;
 314 }