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 - 2008  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 static inline int notify_page_fault(struct pt_regs *regs, int trap)
  25 {
  26         int ret = 0;
  27
  28 #ifdef CONFIG_KPROBES
  29         if (!user_mode(regs)) {
  30                 preempt_disable();
  31                 if (kprobe_running() && kprobe_fault_handler(regs, trap))
  32                         ret = 1;
  33                 preempt_enable();
  34         }
  35 #endif
  36
  37         return ret;
  38 }
  39
  40 /*
  41  * This routine handles page faults.  It determines the address,
  42  * and the problem, and then passes it off to one of the appropriate
  43  * routines.
  44  */
  45 asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
  46                                         unsigned long writeaccess,
  47                                         unsigned long address)
  48 {
  49         struct task_struct *tsk;
  50         struct mm_struct *mm;
  51         struct vm_area_struct * vma;
  52         int si_code;
  53         int fault;
  54         siginfo_t info;
  55
  56         /*
  57          * We don't bother with any notifier callbacks here, as they are
  58          * all handled through the __do_page_fault() fast-path.
  59          */
  60
  61         tsk = current;
  62         si_code = SEGV_MAPERR;
  63
  64         if (unlikely(address >= TASK_SIZE)) {
  65                 /*
  66                  * Synchronize this task's top level page-table
  67                  * with the 'reference' page table.
  68                  *
  69                  * Do _not_ use "tsk" here. We might be inside
  70                  * an interrupt in the middle of a task switch..
  71                  */
  72                 int offset = pgd_index(address);
  73                 pgd_t *pgd, *pgd_k;
  74                 pud_t *pud, *pud_k;
  75                 pmd_t *pmd, *pmd_k;
  76
  77                 pgd = get_TTB() + offset;
  78                 pgd_k = swapper_pg_dir + offset;
  79
  80                 if (!pgd_present(*pgd)) {
  81                         if (!pgd_present(*pgd_k))
  82                                 goto bad_area_nosemaphore;
  83                         set_pgd(pgd, *pgd_k);
  84                         return;
  85                 }
  86
  87                 pud = pud_offset(pgd, address);
  88                 pud_k = pud_offset(pgd_k, address);
  89
  90                 if (!pud_present(*pud)) {
  91                         if (!pud_present(*pud_k))
  92                                 goto bad_area_nosemaphore;
  93                         set_pud(pud, *pud_k);
  94                         return;
  95                 }
  96
  97                 pmd = pmd_offset(pud, address);
  98                 pmd_k = pmd_offset(pud_k, address);
  99                 if (pmd_present(*pmd) || !pmd_present(*pmd_k))
 100                         goto bad_area_nosemaphore;
 101                 set_pmd(pmd, *pmd_k);
 102
 103                 return;
 104         }
 105
 106         /* Only enable interrupts if they were on before the fault */
 107         if ((regs->sr & SR_IMASK) != SR_IMASK) {
 108                 trace_hardirqs_on();
 109                 local_irq_enable();
 110         }
 111
 112         mm = tsk->mm;
 113
 114         /*
 115          * If we're in an interrupt or have no user
 116          * context, we must not take the fault..
 117          */
 118         if (in_atomic() || !mm)
 119                 goto no_context;
 120
 121         down_read(&mm->mmap_sem);
 122
 123         vma = find_vma(mm, address);
 124         if (!vma)
 125                 goto bad_area;
 126         if (vma->vm_start <= address)
 127                 goto good_area;
 128         if (!(vma->vm_flags & VM_GROWSDOWN))
 129                 goto bad_area;
 130         if (expand_stack(vma, address))
 131                 goto bad_area;
 132 /*
 133  * Ok, we have a good vm_area for this memory access, so
 134  * we can handle it..
 135  */
 136 good_area:
 137         si_code = SEGV_ACCERR;
 138         if (writeaccess) {
 139                 if (!(vma->vm_flags & VM_WRITE))
 140                         goto bad_area;
 141         } else {
 142                 if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
 143                         goto bad_area;
 144         }
 145
 146         /*
 147          * If for any reason at all we couldn't handle the fault,
 148          * make sure we exit gracefully rather than endlessly redo
 149          * the fault.
 150          */
 151 survive:
 152         fault = handle_mm_fault(mm, vma, address, writeaccess);
 153         if (unlikely(fault & VM_FAULT_ERROR)) {
 154                 if (fault & VM_FAULT_OOM)
 155                         goto out_of_memory;
 156                 else if (fault & VM_FAULT_SIGBUS)
 157                         goto do_sigbus;
 158                 BUG();
 159         }
 160         if (fault & VM_FAULT_MAJOR)
 161                 tsk->maj_flt++;
 162         else
 163                 tsk->min_flt++;
 164
 165         up_read(&mm->mmap_sem);
 166         return;
 167
 168 /*
 169  * Something tried to access memory that isn't in our memory map..
 170  * Fix it, but check if it's kernel or user first..
 171  */
 172 bad_area:
 173         up_read(&mm->mmap_sem);
 174
 175 bad_area_nosemaphore:
 176         if (user_mode(regs)) {
 177                 info.si_signo = SIGSEGV;
 178                 info.si_errno = 0;
 179                 info.si_code = si_code;
 180                 info.si_addr = (void *) address;
 181                 force_sig_info(SIGSEGV, &info, tsk);
 182                 return;
 183         }
 184
 185 no_context:
 186         /* Are we prepared to handle this kernel fault?  */
 187         if (fixup_exception(regs))
 188                 return;
 189
 190         if (handle_trapped_io(regs, address))
 191                 return;
 192 /*
 193  * Oops. The kernel tried to access some bad page. We'll have to
 194  * terminate things with extreme prejudice.
 195  *
 196  */
 197
 198         bust_spinlocks(1);
 199
 200         if (oops_may_print()) {
 201                 unsigned long page;
 202
 203                 if (address < PAGE_SIZE)
 204                         printk(KERN_ALERT "Unable to handle kernel NULL "
 205                                           "pointer dereference");
 206                 else
 207                         printk(KERN_ALERT "Unable to handle kernel paging "
 208                                           "request");
 209                 printk(" at virtual address %08lx\n", address);
 210                 printk(KERN_ALERT "pc = %08lx\n", regs->pc);
 211                 page = (unsigned long)get_TTB();
 212                 if (page) {
 213                         page = ((__typeof__(page) *)page)[address >> PGDIR_SHIFT];
 214                         printk(KERN_ALERT "*pde = %08lx\n", page);
 215                         if (page & _PAGE_PRESENT) {
 216                                 page &= PAGE_MASK;
 217                                 address &= 0x003ff000;
 218                                 page = ((__typeof__(page) *)
 219                                                 __va(page))[address >>
 220                                                             PAGE_SHIFT];
 221                                 printk(KERN_ALERT "*pte = %08lx\n", page);
 222                         }
 223                 }
 224         }
 225
 226         die("Oops", regs, writeaccess);
 227         bust_spinlocks(0);
 228         do_exit(SIGKILL);
 229
 230 /*
 231  * We ran out of memory, or some other thing happened to us that made
 232  * us unable to handle the page fault gracefully.
 233  */
 234 out_of_memory:
 235         up_read(&mm->mmap_sem);
 236         if (is_global_init(current)) {
 237                 yield();
 238                 down_read(&mm->mmap_sem);
 239                 goto survive;
 240         }
 241         printk("VM: killing process %s\n", tsk->comm);
 242         if (user_mode(regs))
 243                 do_group_exit(SIGKILL);
 244         goto no_context;
 245
 246 do_sigbus:
 247         up_read(&mm->mmap_sem);
 248
 249         /*
 250          * Send a sigbus, regardless of whether we were in kernel
 251          * or user mode.
 252          */
 253         info.si_signo = SIGBUS;
 254         info.si_errno = 0;
 255         info.si_code = BUS_ADRERR;
 256         info.si_addr = (void *)address;
 257         force_sig_info(SIGBUS, &info, tsk);
 258
 259         /* Kernel mode? Handle exceptions or die */
 260         if (!user_mode(regs))
 261                 goto no_context;
 262 }
 263
 264 #ifdef CONFIG_SH_STORE_QUEUES
 265 /*
 266  * This is a special case for the SH-4 store queues, as pages for this
 267  * space still need to be faulted in before it's possible to flush the
 268  * store queue cache for writeout to the remapped region.
 269  */
 270 #define P3_ADDR_MAX             (P4SEG_STORE_QUE + 0x04000000)
 271 #else
 272 #define P3_ADDR_MAX             P4SEG
 273 #endif
 274
 275 /*
 276  * Called with interrupts disabled.
 277  */
 278 asmlinkage int __kprobes __do_page_fault(struct pt_regs *regs,
 279                                          unsigned long writeaccess,
 280                                          unsigned long address)
 281 {
 282         pgd_t *pgd;
 283         pud_t *pud;
 284         pmd_t *pmd;
 285         pte_t *pte;
 286         pte_t entry;
 287
 288         if (notify_page_fault(regs, lookup_exception_vector()))
 289                 return 0;
 290
 291 #ifdef CONFIG_SH_KGDB
 292         if (kgdb_nofault && kgdb_bus_err_hook)
 293                 kgdb_bus_err_hook();
 294 #endif
 295
 296         /*
 297          * We don't take page faults for P1, P2, and parts of P4, these
 298          * are always mapped, whether it be due to legacy behaviour in
 299          * 29-bit mode, or due to PMB configuration in 32-bit mode.
 300          */
 301         if (address >= P3SEG && address < P3_ADDR_MAX) {
 302                 pgd = pgd_offset_k(address);
 303         } else {
 304                 if (unlikely(address >= TASK_SIZE || !current->mm))
 305                         return 1;
 306
 307                 pgd = pgd_offset(current->mm, address);
 308         }
 309
 310         pud = pud_offset(pgd, address);
 311         if (pud_none_or_clear_bad(pud))
 312                 return 1;
 313         pmd = pmd_offset(pud, address);
 314         if (pmd_none_or_clear_bad(pmd))
 315                 return 1;
 316
 317         pte = pte_offset_kernel(pmd, address);
 318         entry = *pte;
 319         if (unlikely(pte_none(entry) || pte_not_present(entry)))
 320                 return 1;
 321         if (unlikely(writeaccess && !pte_write(entry)))
 322                 return 1;
 323
 324         if (writeaccess)
 325                 entry = pte_mkdirty(entry);
 326         entry = pte_mkyoung(entry);
 327
 328 #if defined(CONFIG_CPU_SH4) && !defined(CONFIG_SMP)
 329         /*
 330          * ITLB is not affected by "ldtlb" instruction.
 331          * So, we need to flush the entry by ourselves.
 332          */
 333         local_flush_tlb_one(get_asid(), address & PAGE_MASK);
 334 #endif
 335
 336         set_pte(pte, entry);
 337         update_mmu_cache(NULL, address, entry);
 338
 339         return 0;
 340 }