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 #ifdef CONFIG_KPROBES
  25 static inline int notify_page_fault(struct pt_regs *regs, int trap)
  26 {
  27         int ret = 0;
  28
  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
  36         return ret;
  37 }
  38 #else
  39 static inline int notify_page_fault(struct pt_regs *regs, int trap)
  40 {
  41         return 0;
  42 }
  43 #endif
  44
  45 /*
  46  * This routine handles page faults.  It determines the address,
  47  * and the problem, and then passes it off to one of the appropriate
  48  * routines.
  49  */
  50 asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
  51                                         unsigned long writeaccess,
  52                                         unsigned long address)
  53 {
  54         struct task_struct *tsk;
  55         struct mm_struct *mm;
  56         struct vm_area_struct * vma;
  57         int si_code;
  58         int fault;
  59         siginfo_t info;
  60
  61         if (notify_page_fault(regs, writeaccess))
  62                 return;
  63
  64 #ifdef CONFIG_SH_KGDB
  65         if (kgdb_nofault && kgdb_bus_err_hook)
  66                 kgdb_bus_err_hook();
  67 #endif
  68
  69         tsk = current;
  70         si_code = SEGV_MAPERR;
  71
  72         if (unlikely(address >= TASK_SIZE)) {
  73                 /*
  74                  * Synchronize this task's top level page-table
  75                  * with the 'reference' page table.
  76                  *
  77                  * Do _not_ use "tsk" here. We might be inside
  78                  * an interrupt in the middle of a task switch..
  79                  */
  80                 int offset = pgd_index(address);
  81                 pgd_t *pgd, *pgd_k;
  82                 pud_t *pud, *pud_k;
  83                 pmd_t *pmd, *pmd_k;
  84
  85                 pgd = get_TTB() + offset;
  86                 pgd_k = swapper_pg_dir + offset;
  87
  88                 if (!pgd_present(*pgd)) {
  89                         if (!pgd_present(*pgd_k))
  90                                 goto bad_area_nosemaphore;
  91                         set_pgd(pgd, *pgd_k);
  92                         return;
  93                 }
  94
  95                 pud = pud_offset(pgd, address);
  96                 pud_k = pud_offset(pgd_k, address);
  97
  98                 if (!pud_present(*pud)) {
  99                         if (!pud_present(*pud_k))
 100                                 goto bad_area_nosemaphore;
 101                         set_pud(pud, *pud_k);
 102                         return;
 103                 }
 104
 105                 pmd = pmd_offset(pud, address);
 106                 pmd_k = pmd_offset(pud_k, address);
 107                 if (pmd_present(*pmd) || !pmd_present(*pmd_k))
 108                         goto bad_area_nosemaphore;
 109                 set_pmd(pmd, *pmd_k);
 110
 111                 return;
 112         }
 113
 114         /* Only enable interrupts if they were on before the fault */
 115         if ((regs->sr & SR_IMASK) != SR_IMASK) {
 116                 trace_hardirqs_on();
 117                 local_irq_enable();
 118         }
 119
 120         mm = tsk->mm;
 121
 122         /*
 123          * If we're in an interrupt or have no user
 124          * context, we must not take the fault..
 125          */
 126         if (in_atomic() || !mm)
 127                 goto no_context;
 128
 129         down_read(&mm->mmap_sem);
 130
 131         vma = find_vma(mm, address);
 132         if (!vma)
 133                 goto bad_area;
 134         if (vma->vm_start <= address)
 135                 goto good_area;
 136         if (!(vma->vm_flags & VM_GROWSDOWN))
 137                 goto bad_area;
 138         if (expand_stack(vma, address))
 139                 goto bad_area;
 140 /*
 141  * Ok, we have a good vm_area for this memory access, so
 142  * we can handle it..
 143  */
 144 good_area:
 145         si_code = SEGV_ACCERR;
 146         if (writeaccess) {
 147                 if (!(vma->vm_flags & VM_WRITE))
 148                         goto bad_area;
 149         } else {
 150                 if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
 151                         goto bad_area;
 152         }
 153
 154         /*
 155          * If for any reason at all we couldn't handle the fault,
 156          * make sure we exit gracefully rather than endlessly redo
 157          * the fault.
 158          */
 159 survive:
 160         fault = handle_mm_fault(mm, vma, address, writeaccess);
 161         if (unlikely(fault & VM_FAULT_ERROR)) {
 162                 if (fault & VM_FAULT_OOM)
 163                         goto out_of_memory;
 164                 else if (fault & VM_FAULT_SIGBUS)
 165                         goto do_sigbus;
 166                 BUG();
 167         }
 168         if (fault & VM_FAULT_MAJOR)
 169                 tsk->maj_flt++;
 170         else
 171                 tsk->min_flt++;
 172
 173         up_read(&mm->mmap_sem);
 174         return;
 175
 176 /*
 177  * Something tried to access memory that isn't in our memory map..
 178  * Fix it, but check if it's kernel or user first..
 179  */
 180 bad_area:
 181         up_read(&mm->mmap_sem);
 182
 183 bad_area_nosemaphore:
 184         if (user_mode(regs)) {
 185                 info.si_signo = SIGSEGV;
 186                 info.si_errno = 0;
 187                 info.si_code = si_code;
 188                 info.si_addr = (void *) address;
 189                 force_sig_info(SIGSEGV, &info, tsk);
 190                 return;
 191         }
 192
 193 no_context:
 194         /* Are we prepared to handle this kernel fault?  */
 195         if (fixup_exception(regs))
 196                 return;
 197
 198         if (handle_trapped_io(regs, address))
 199                 return;
 200 /*
 201  * Oops. The kernel tried to access some bad page. We'll have to
 202  * terminate things with extreme prejudice.
 203  *
 204  */
 205
 206         bust_spinlocks(1);
 207
 208         if (oops_may_print()) {
 209                 unsigned long page;
 210
 211                 if (address < PAGE_SIZE)
 212                         printk(KERN_ALERT "Unable to handle kernel NULL "
 213                                           "pointer dereference");
 214                 else
 215                         printk(KERN_ALERT "Unable to handle kernel paging "
 216                                           "request");
 217                 printk(" at virtual address %08lx\n", address);
 218                 printk(KERN_ALERT "pc = %08lx\n", regs->pc);
 219                 page = (unsigned long)get_TTB();
 220                 if (page) {
 221                         page = ((__typeof__(page) *)page)[address >> PGDIR_SHIFT];
 222                         printk(KERN_ALERT "*pde = %08lx\n", page);
 223                         if (page & _PAGE_PRESENT) {
 224                                 page &= PAGE_MASK;
 225                                 address &= 0x003ff000;
 226                                 page = ((__typeof__(page) *)
 227                                                 __va(page))[address >>
 228                                                             PAGE_SHIFT];
 229                                 printk(KERN_ALERT "*pte = %08lx\n", page);
 230                         }
 231                 }
 232         }
 233
 234         die("Oops", regs, writeaccess);
 235         bust_spinlocks(0);
 236         do_exit(SIGKILL);
 237
 238 /*
 239  * We ran out of memory, or some other thing happened to us that made
 240  * us unable to handle the page fault gracefully.
 241  */
 242 out_of_memory:
 243         up_read(&mm->mmap_sem);
 244         if (is_global_init(current)) {
 245                 yield();
 246                 down_read(&mm->mmap_sem);
 247                 goto survive;
 248         }
 249         printk("VM: killing process %s\n", tsk->comm);
 250         if (user_mode(regs))
 251                 do_group_exit(SIGKILL);
 252         goto no_context;
 253
 254 do_sigbus:
 255         up_read(&mm->mmap_sem);
 256
 257         /*
 258          * Send a sigbus, regardless of whether we were in kernel
 259          * or user mode.
 260          */
 261         info.si_signo = SIGBUS;
 262         info.si_errno = 0;
 263         info.si_code = BUS_ADRERR;
 264         info.si_addr = (void *)address;
 265         force_sig_info(SIGBUS, &info, tsk);
 266
 267         /* Kernel mode? Handle exceptions or die */
 268         if (!user_mode(regs))
 269                 goto no_context;
 270 }
 271
 272 #ifdef CONFIG_SH_STORE_QUEUES
 273 /*
 274  * This is a special case for the SH-4 store queues, as pages for this
 275  * space still need to be faulted in before it's possible to flush the
 276  * store queue cache for writeout to the remapped region.
 277  */
 278 #define P3_ADDR_MAX             (P4SEG_STORE_QUE + 0x04000000)
 279 #else
 280 #define P3_ADDR_MAX             P4SEG
 281 #endif
 282
 283 /*
 284  * Called with interrupts disabled.
 285  */
 286 asmlinkage int __kprobes __do_page_fault(struct pt_regs *regs,
 287                                          unsigned long writeaccess,
 288                                          unsigned long address)
 289 {
 290         pgd_t *pgd;
 291         pud_t *pud;
 292         pmd_t *pmd;
 293         pte_t *pte;
 294         pte_t entry;
 295
 296         if (notify_page_fault(regs, writeaccess))
 297                 return 0;
 298
 299 #ifdef CONFIG_SH_KGDB
 300         if (kgdb_nofault && kgdb_bus_err_hook)
 301                 kgdb_bus_err_hook();
 302 #endif
 303
 304         /*
 305          * We don't take page faults for P1, P2, and parts of P4, these
 306          * are always mapped, whether it be due to legacy behaviour in
 307          * 29-bit mode, or due to PMB configuration in 32-bit mode.
 308          */
 309         if (address >= P3SEG && address < P3_ADDR_MAX) {
 310                 pgd = pgd_offset_k(address);
 311         } else {
 312                 if (unlikely(address >= TASK_SIZE || !current->mm))
 313                         return 1;
 314
 315                 pgd = pgd_offset(current->mm, address);
 316         }
 317
 318         pud = pud_offset(pgd, address);
 319         if (pud_none_or_clear_bad(pud))
 320                 return 1;
 321         pmd = pmd_offset(pud, address);
 322         if (pmd_none_or_clear_bad(pmd))
 323                 return 1;
 324
 325         pte = pte_offset_kernel(pmd, address);
 326         entry = *pte;
 327         if (unlikely(pte_none(entry) || pte_not_present(entry)))
 328                 return 1;
 329         if (unlikely(writeaccess && !pte_write(entry)))
 330                 return 1;
 331
 332         if (writeaccess)
 333                 entry = pte_mkdirty(entry);
 334         entry = pte_mkyoung(entry);
 335
 336 #if defined(CONFIG_CPU_SH4) && !defined(CONFIG_SMP)
 337         /*
 338          * ITLB is not affected by "ldtlb" instruction.
 339          * So, we need to flush the entry by ourselves.
 340          */
 341         local_flush_tlb_one(get_asid(), address & PAGE_MASK);
 342 #endif
 343
 344         set_pte(pte, entry);
 345         update_mmu_cache(NULL, address, entry);
 346
 347         return 0;
 348 }