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 <linux/perf_counter.h>
  19 #include <asm/io_trapped.h>
  20 #include <asm/system.h>
  21 #include <asm/mmu_context.h>
  22 #include <asm/tlbflush.h>
  23
  24 static inline int notify_page_fault(struct pt_regs *regs, int trap)
  25 {
  26         int ret = 0;
  27
  28         if (kprobes_built_in() && !user_mode(regs)) {
  29                 preempt_disable();
  30                 if (kprobe_running() && kprobe_fault_handler(regs, trap))
  31                         ret = 1;
  32                 preempt_enable();
  33         }
  34
  35         return ret;
  36 }
  37
  38 /*
  39  * This routine handles page faults.  It determines the address,
  40  * and the problem, and then passes it off to one of the appropriate
  41  * routines.
  42  */
  43 asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
  44                                         unsigned long writeaccess,
  45                                         unsigned long address)
  46 {
  47         struct task_struct *tsk;
  48         struct mm_struct *mm;
  49         struct vm_area_struct * vma;
  50         int si_code;
  51         int fault;
  52         siginfo_t info;
  53
  54         /*
  55          * We don't bother with any notifier callbacks here, as they are
  56          * all handled through the __do_page_fault() fast-path.
  57          */
  58
  59         tsk = current;
  60         si_code = SEGV_MAPERR;
  61
  62         if (unlikely(address >= TASK_SIZE)) {
  63                 /*
  64                  * Synchronize this task's top level page-table
  65                  * with the 'reference' page table.
  66                  *
  67                  * Do _not_ use "tsk" here. We might be inside
  68                  * an interrupt in the middle of a task switch..
  69                  */
  70                 int offset = pgd_index(address);
  71                 pgd_t *pgd, *pgd_k;
  72                 pud_t *pud, *pud_k;
  73                 pmd_t *pmd, *pmd_k;
  74
  75                 pgd = get_TTB() + offset;
  76                 pgd_k = swapper_pg_dir + offset;
  77
  78                 if (!pgd_present(*pgd)) {
  79                         if (!pgd_present(*pgd_k))
  80                                 goto bad_area_nosemaphore;
  81                         set_pgd(pgd, *pgd_k);
  82                         return;
  83                 }
  84
  85                 pud = pud_offset(pgd, address);
  86                 pud_k = pud_offset(pgd_k, address);
  87
  88                 if (!pud_present(*pud)) {
  89                         if (!pud_present(*pud_k))
  90                                 goto bad_area_nosemaphore;
  91                         set_pud(pud, *pud_k);
  92                         return;
  93                 }
  94
  95                 pmd = pmd_offset(pud, address);
  96                 pmd_k = pmd_offset(pud_k, address);
  97                 if (pmd_present(*pmd) || !pmd_present(*pmd_k))
  98                         goto bad_area_nosemaphore;
  99                 set_pmd(pmd, *pmd_k);
 100
 101                 return;
 102         }
 103
 104         mm = tsk->mm;
 105
 106         if (unlikely(notify_page_fault(regs, lookup_exception_vector())))
 107                 return;
 108
 109         /* Only enable interrupts if they were on before the fault */
 110         if ((regs->sr & SR_IMASK) != SR_IMASK)
 111                 local_irq_enable();
 112
 113         perf_swcounter_event(PERF_COUNT_SW_PAGE_FAULTS, 1, 0, regs, address);
 114
 115         /*
 116          * If we're in an interrupt or have no user
 117          * context, we must not take the fault..
 118          */
 119         if (in_atomic() || !mm)
 120                 goto no_context;
 121
 122         down_read(&mm->mmap_sem);
 123
 124         vma = find_vma(mm, address);
 125         if (!vma)
 126                 goto bad_area;
 127         if (vma->vm_start <= address)
 128                 goto good_area;
 129         if (!(vma->vm_flags & VM_GROWSDOWN))
 130                 goto bad_area;
 131         if (expand_stack(vma, address))
 132                 goto bad_area;
 133 /*
 134  * Ok, we have a good vm_area for this memory access, so
 135  * we can handle it..
 136  */
 137 good_area:
 138         si_code = SEGV_ACCERR;
 139         if (writeaccess) {
 140                 if (!(vma->vm_flags & VM_WRITE))
 141                         goto bad_area;
 142         } else {
 143                 if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
 144                         goto bad_area;
 145         }
 146
 147         /*
 148          * If for any reason at all we couldn't handle the fault,
 149          * make sure we exit gracefully rather than endlessly redo
 150          * the fault.
 151          */
 152 survive:
 153         fault = handle_mm_fault(mm, vma, address, writeaccess ? FAULT_FLAG_WRITE : 0);
 154         if (unlikely(fault & VM_FAULT_ERROR)) {
 155                 if (fault & VM_FAULT_OOM)
 156                         goto out_of_memory;
 157                 else if (fault & VM_FAULT_SIGBUS)
 158                         goto do_sigbus;
 159                 BUG();
 160         }
 161         if (fault & VM_FAULT_MAJOR) {
 162                 tsk->maj_flt++;
 163                 perf_swcounter_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, 0,
 164                                      regs, address);
 165         } else {
 166                 tsk->min_flt++;
 167                 perf_swcounter_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, 0,
 168                                      regs, address);
 169         }
 170
 171         up_read(&mm->mmap_sem);
 172         return;
 173
 174 /*
 175  * Something tried to access memory that isn't in our memory map..
 176  * Fix it, but check if it's kernel or user first..
 177  */
 178 bad_area:
 179         up_read(&mm->mmap_sem);
 180
 181 bad_area_nosemaphore:
 182         if (user_mode(regs)) {
 183                 info.si_signo = SIGSEGV;
 184                 info.si_errno = 0;
 185                 info.si_code = si_code;
 186                 info.si_addr = (void *) address;
 187                 force_sig_info(SIGSEGV, &info, tsk);
 188                 return;
 189         }
 190
 191 no_context:
 192         /* Are we prepared to handle this kernel fault?  */
 193         if (fixup_exception(regs))
 194                 return;
 195
 196         if (handle_trapped_io(regs, address))
 197                 return;
 198 /*
 199  * Oops. The kernel tried to access some bad page. We'll have to
 200  * terminate things with extreme prejudice.
 201  *
 202  */
 203
 204         bust_spinlocks(1);
 205
 206         if (oops_may_print()) {
 207                 unsigned long page;
 208
 209                 if (address < PAGE_SIZE)
 210                         printk(KERN_ALERT "Unable to handle kernel NULL "
 211                                           "pointer dereference");
 212                 else
 213                         printk(KERN_ALERT "Unable to handle kernel paging "
 214                                           "request");
 215                 printk(" at virtual address %08lx\n", address);
 216                 printk(KERN_ALERT "pc = %08lx\n", regs->pc);
 217                 page = (unsigned long)get_TTB();
 218                 if (page) {
 219                         page = ((__typeof__(page) *)page)[address >> PGDIR_SHIFT];
 220                         printk(KERN_ALERT "*pde = %08lx\n", page);
 221                         if (page & _PAGE_PRESENT) {
 222                                 page &= PAGE_MASK;
 223                                 address &= 0x003ff000;
 224                                 page = ((__typeof__(page) *)
 225                                                 __va(page))[address >>
 226                                                             PAGE_SHIFT];
 227                                 printk(KERN_ALERT "*pte = %08lx\n", page);
 228                         }
 229                 }
 230         }
 231
 232         die("Oops", regs, writeaccess);
 233         bust_spinlocks(0);
 234         do_exit(SIGKILL);
 235
 236 /*
 237  * We ran out of memory, or some other thing happened to us that made
 238  * us unable to handle the page fault gracefully.
 239  */
 240 out_of_memory:
 241         up_read(&mm->mmap_sem);
 242         if (is_global_init(current)) {
 243                 yield();
 244                 down_read(&mm->mmap_sem);
 245                 goto survive;
 246         }
 247         printk("VM: killing process %s\n", tsk->comm);
 248         if (user_mode(regs))
 249                 do_group_exit(SIGKILL);
 250         goto no_context;
 251
 252 do_sigbus:
 253         up_read(&mm->mmap_sem);
 254
 255         /*
 256          * Send a sigbus, regardless of whether we were in kernel
 257          * or user mode.
 258          */
 259         info.si_signo = SIGBUS;
 260         info.si_errno = 0;
 261         info.si_code = BUS_ADRERR;
 262         info.si_addr = (void *)address;
 263         force_sig_info(SIGBUS, &info, tsk);
 264
 265         /* Kernel mode? Handle exceptions or die */
 266         if (!user_mode(regs))
 267                 goto no_context;
 268 }
 269
 270 /*
 271  * Called with interrupts disabled.
 272  */
 273 asmlinkage int __kprobes __do_page_fault(struct pt_regs *regs,
 274                                          unsigned long writeaccess,
 275                                          unsigned long address)
 276 {
 277         pgd_t *pgd;
 278         pud_t *pud;
 279         pmd_t *pmd;
 280         pte_t *pte;
 281         pte_t entry;
 282         int ret = 1;
 283
 284         /*
 285          * We don't take page faults for P1, P2, and parts of P4, these
 286          * are always mapped, whether it be due to legacy behaviour in
 287          * 29-bit mode, or due to PMB configuration in 32-bit mode.
 288          */
 289         if (address >= P3SEG && address < P3_ADDR_MAX) {
 290                 pgd = pgd_offset_k(address);
 291         } else {
 292                 if (unlikely(address >= TASK_SIZE || !current->mm))
 293                         goto out;
 294
 295                 pgd = pgd_offset(current->mm, address);
 296         }
 297
 298         pud = pud_offset(pgd, address);
 299         if (pud_none_or_clear_bad(pud))
 300                 goto out;
 301         pmd = pmd_offset(pud, address);
 302         if (pmd_none_or_clear_bad(pmd))
 303                 goto out;
 304         pte = pte_offset_kernel(pmd, address);
 305         entry = *pte;
 306         if (unlikely(pte_none(entry) || pte_not_present(entry)))
 307                 goto out;
 308         if (unlikely(writeaccess && !pte_write(entry)))
 309                 goto out;
 310
 311         if (writeaccess)
 312                 entry = pte_mkdirty(entry);
 313         entry = pte_mkyoung(entry);
 314
 315 #if defined(CONFIG_CPU_SH4) && !defined(CONFIG_SMP)
 316         /*
 317          * ITLB is not affected by "ldtlb" instruction.
 318          * So, we need to flush the entry by ourselves.
 319          */
 320         local_flush_tlb_one(get_asid(), address & PAGE_MASK);
 321 #endif
 322
 323         set_pte(pte, entry);
 324         update_mmu_cache(NULL, address, entry);
 325
 326         ret = 0;
 327 out:
 328         return ret;
 329 }