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         if (notify_page_fault(regs, lookup_exception_vector()))
  57                 return;
  58
  59 #ifdef CONFIG_SH_KGDB
  60         if (kgdb_nofault && kgdb_bus_err_hook)
  61                 kgdb_bus_err_hook();
  62 #endif
  63
  64         tsk = current;
  65         si_code = SEGV_MAPERR;
  66
  67         if (unlikely(address >= TASK_SIZE)) {
  68                 /*
  69                  * Synchronize this task's top level page-table
  70                  * with the 'reference' page table.
  71                  *
  72                  * Do _not_ use "tsk" here. We might be inside
  73                  * an interrupt in the middle of a task switch..
  74                  */
  75                 int offset = pgd_index(address);
  76                 pgd_t *pgd, *pgd_k;
  77                 pud_t *pud, *pud_k;
  78                 pmd_t *pmd, *pmd_k;
  79
  80                 pgd = get_TTB() + offset;
  81                 pgd_k = swapper_pg_dir + offset;
  82
  83                 if (!pgd_present(*pgd)) {
  84                         if (!pgd_present(*pgd_k))
  85                                 goto bad_area_nosemaphore;
  86                         set_pgd(pgd, *pgd_k);
  87                         return;
  88                 }
  89
  90                 pud = pud_offset(pgd, address);
  91                 pud_k = pud_offset(pgd_k, address);
  92
  93                 if (!pud_present(*pud)) {
  94                         if (!pud_present(*pud_k))
  95                                 goto bad_area_nosemaphore;
  96                         set_pud(pud, *pud_k);
  97                         return;
  98                 }
  99
 100                 pmd = pmd_offset(pud, address);
 101                 pmd_k = pmd_offset(pud_k, address);
 102                 if (pmd_present(*pmd) || !pmd_present(*pmd_k))
 103                         goto bad_area_nosemaphore;
 104                 set_pmd(pmd, *pmd_k);
 105
 106                 return;
 107         }
 108
 109         /* Only enable interrupts if they were on before the fault */
 110         if ((regs->sr & SR_IMASK) != SR_IMASK) {
 111                 trace_hardirqs_on();
 112                 local_irq_enable();
 113         }
 114
 115         mm = tsk->mm;
 116
 117         /*
 118          * If we're in an interrupt or have no user
 119          * context, we must not take the fault..
 120          */
 121         if (in_atomic() || !mm)
 122                 goto no_context;
 123
 124         down_read(&mm->mmap_sem);
 125
 126         vma = find_vma(mm, address);
 127         if (!vma)
 128                 goto bad_area;
 129         if (vma->vm_start <= address)
 130                 goto good_area;
 131         if (!(vma->vm_flags & VM_GROWSDOWN))
 132                 goto bad_area;
 133         if (expand_stack(vma, address))
 134                 goto bad_area;
 135 /*
 136  * Ok, we have a good vm_area for this memory access, so
 137  * we can handle it..
 138  */
 139 good_area:
 140         si_code = SEGV_ACCERR;
 141         if (writeaccess) {
 142                 if (!(vma->vm_flags & VM_WRITE))
 143                         goto bad_area;
 144         } else {
 145                 if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
 146                         goto bad_area;
 147         }
 148
 149         /*
 150          * If for any reason at all we couldn't handle the fault,
 151          * make sure we exit gracefully rather than endlessly redo
 152          * the fault.
 153          */
 154 survive:
 155         fault = handle_mm_fault(mm, vma, address, writeaccess);
 156         if (unlikely(fault & VM_FAULT_ERROR)) {
 157                 if (fault & VM_FAULT_OOM)
 158                         goto out_of_memory;
 159                 else if (fault & VM_FAULT_SIGBUS)
 160                         goto do_sigbus;
 161                 BUG();
 162         }
 163         if (fault & VM_FAULT_MAJOR)
 164                 tsk->maj_flt++;
 165         else
 166                 tsk->min_flt++;
 167
 168         up_read(&mm->mmap_sem);
 169         return;
 170
 171 /*
 172  * Something tried to access memory that isn't in our memory map..
 173  * Fix it, but check if it's kernel or user first..
 174  */
 175 bad_area:
 176         up_read(&mm->mmap_sem);
 177
 178 bad_area_nosemaphore:
 179         if (user_mode(regs)) {
 180                 info.si_signo = SIGSEGV;
 181                 info.si_errno = 0;
 182                 info.si_code = si_code;
 183                 info.si_addr = (void *) address;
 184                 force_sig_info(SIGSEGV, &info, tsk);
 185                 return;
 186         }
 187
 188 no_context:
 189         /* Are we prepared to handle this kernel fault?  */
 190         if (fixup_exception(regs))
 191                 return;
 192
 193         if (handle_trapped_io(regs, address))
 194                 return;
 195 /*
 196  * Oops. The kernel tried to access some bad page. We'll have to
 197  * terminate things with extreme prejudice.
 198  *
 199  */
 200
 201         bust_spinlocks(1);
 202
 203         if (oops_may_print()) {
 204                 unsigned long page;
 205
 206                 if (address < PAGE_SIZE)
 207                         printk(KERN_ALERT "Unable to handle kernel NULL "
 208                                           "pointer dereference");
 209                 else
 210                         printk(KERN_ALERT "Unable to handle kernel paging "
 211                                           "request");
 212                 printk(" at virtual address %08lx\n", address);
 213                 printk(KERN_ALERT "pc = %08lx\n", regs->pc);
 214                 page = (unsigned long)get_TTB();
 215                 if (page) {
 216                         page = ((__typeof__(page) *)page)[address >> PGDIR_SHIFT];
 217                         printk(KERN_ALERT "*pde = %08lx\n", page);
 218                         if (page & _PAGE_PRESENT) {
 219                                 page &= PAGE_MASK;
 220                                 address &= 0x003ff000;
 221                                 page = ((__typeof__(page) *)
 222                                                 __va(page))[address >>
 223                                                             PAGE_SHIFT];
 224                                 printk(KERN_ALERT "*pte = %08lx\n", page);
 225                         }
 226                 }
 227         }
 228
 229         die("Oops", regs, writeaccess);
 230         bust_spinlocks(0);
 231         do_exit(SIGKILL);
 232
 233 /*
 234  * We ran out of memory, or some other thing happened to us that made
 235  * us unable to handle the page fault gracefully.
 236  */
 237 out_of_memory:
 238         up_read(&mm->mmap_sem);
 239         if (is_global_init(current)) {
 240                 yield();
 241                 down_read(&mm->mmap_sem);
 242                 goto survive;
 243         }
 244         printk("VM: killing process %s\n", tsk->comm);
 245         if (user_mode(regs))
 246                 do_group_exit(SIGKILL);
 247         goto no_context;
 248
 249 do_sigbus:
 250         up_read(&mm->mmap_sem);
 251
 252         /*
 253          * Send a sigbus, regardless of whether we were in kernel
 254          * or user mode.
 255          */
 256         info.si_signo = SIGBUS;
 257         info.si_errno = 0;
 258         info.si_code = BUS_ADRERR;
 259         info.si_addr = (void *)address;
 260         force_sig_info(SIGBUS, &info, tsk);
 261
 262         /* Kernel mode? Handle exceptions or die */
 263         if (!user_mode(regs))
 264                 goto no_context;
 265 }
 266
 267 #ifdef CONFIG_SH_STORE_QUEUES
 268 /*
 269  * This is a special case for the SH-4 store queues, as pages for this
 270  * space still need to be faulted in before it's possible to flush the
 271  * store queue cache for writeout to the remapped region.
 272  */
 273 #define P3_ADDR_MAX             (P4SEG_STORE_QUE + 0x04000000)
 274 #else
 275 #define P3_ADDR_MAX             P4SEG
 276 #endif
 277
 278 /*
 279  * Called with interrupts disabled.
 280  */
 281 asmlinkage int __kprobes __do_page_fault(struct pt_regs *regs,
 282                                          unsigned long writeaccess,
 283                                          unsigned long address)
 284 {
 285         pgd_t *pgd;
 286         pud_t *pud;
 287         pmd_t *pmd;
 288         pte_t *pte;
 289         pte_t entry;
 290
 291         if (notify_page_fault(regs, lookup_exception_vector()))
 292                 return 0;
 293
 294 #ifdef CONFIG_SH_KGDB
 295         if (kgdb_nofault && kgdb_bus_err_hook)
 296                 kgdb_bus_err_hook();
 297 #endif
 298
 299         /*
 300          * We don't take page faults for P1, P2, and parts of P4, these
 301          * are always mapped, whether it be due to legacy behaviour in
 302          * 29-bit mode, or due to PMB configuration in 32-bit mode.
 303          */
 304         if (address >= P3SEG && address < P3_ADDR_MAX) {
 305                 pgd = pgd_offset_k(address);
 306         } else {
 307                 if (unlikely(address >= TASK_SIZE || !current->mm))
 308                         return 1;
 309
 310                 pgd = pgd_offset(current->mm, address);
 311         }
 312
 313         pud = pud_offset(pgd, address);
 314         if (pud_none_or_clear_bad(pud))
 315                 return 1;
 316         pmd = pmd_offset(pud, address);
 317         if (pmd_none_or_clear_bad(pmd))
 318                 return 1;
 319
 320         pte = pte_offset_kernel(pmd, address);
 321         entry = *pte;
 322         if (unlikely(pte_none(entry) || pte_not_present(entry)))
 323                 return 1;
 324         if (unlikely(writeaccess && !pte_write(entry)))
 325                 return 1;
 326
 327         if (writeaccess)
 328                 entry = pte_mkdirty(entry);
 329         entry = pte_mkyoung(entry);
 330
 331 #if defined(CONFIG_CPU_SH4) && !defined(CONFIG_SMP)
 332         /*
 333          * ITLB is not affected by "ldtlb" instruction.
 334          * So, we need to flush the entry by ourselves.
 335          */
 336         local_flush_tlb_one(get_asid(), address & PAGE_MASK);
 337 #endif
 338
 339         set_pte(pte, entry);
 340         update_mmu_cache(NULL, address, entry);
 341
 342         return 0;
 343 }