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/marker.h>
  19 #include <asm/io_trapped.h>
  20 #include <asm/system.h>
  21 #include <asm/mmu_context.h>
  22 #include <asm/tlbflush.h>
  23 #include <asm/kgdb.h>
  24
  25 /*
  26  * This routine handles page faults.  It determines the address,
  27  * and the problem, and then passes it off to one of the appropriate
  28  * routines.
  29  */
  30 asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
  31                                         unsigned long writeaccess,
  32                                         unsigned long address)
  33 {
  34         struct task_struct *tsk;
  35         struct mm_struct *mm;
  36         struct vm_area_struct * vma;
  37         int si_code;
  38         int fault;
  39         siginfo_t info;
  40
  41         /*
  42          * We don't bother with any notifier callbacks here, as they are
  43          * all handled through the __do_page_fault() fast-path.
  44          */
  45
  46         tsk = current;
  47         si_code = SEGV_MAPERR;
  48
  49         if (unlikely(address >= TASK_SIZE)) {
  50                 /*
  51                  * Synchronize this task's top level page-table
  52                  * with the 'reference' page table.
  53                  *
  54                  * Do _not_ use "tsk" here. We might be inside
  55                  * an interrupt in the middle of a task switch..
  56                  */
  57                 int offset = pgd_index(address);
  58                 pgd_t *pgd, *pgd_k;
  59                 pud_t *pud, *pud_k;
  60                 pmd_t *pmd, *pmd_k;
  61
  62                 pgd = get_TTB() + offset;
  63                 pgd_k = swapper_pg_dir + offset;
  64
  65                 if (!pgd_present(*pgd)) {
  66                         if (!pgd_present(*pgd_k))
  67                                 goto bad_area_nosemaphore;
  68                         set_pgd(pgd, *pgd_k);
  69                         return;
  70                 }
  71
  72                 pud = pud_offset(pgd, address);
  73                 pud_k = pud_offset(pgd_k, address);
  74
  75                 if (!pud_present(*pud)) {
  76                         if (!pud_present(*pud_k))
  77                                 goto bad_area_nosemaphore;
  78                         set_pud(pud, *pud_k);
  79                         return;
  80                 }
  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         /* Only enable interrupts if they were on before the fault */
  92         if ((regs->sr & SR_IMASK) != SR_IMASK) {
  93                 trace_hardirqs_on();
  94                 local_irq_enable();
  95         }
  96
  97         mm = tsk->mm;
  98
  99         /*
 100          * If we're in an interrupt or have no user
 101          * context, we must not take the fault..
 102          */
 103         if (in_atomic() || !mm)
 104                 goto no_context;
 105
 106         down_read(&mm->mmap_sem);
 107
 108         vma = find_vma(mm, address);
 109         if (!vma)
 110                 goto bad_area;
 111         if (vma->vm_start <= address)
 112                 goto good_area;
 113         if (!(vma->vm_flags & VM_GROWSDOWN))
 114                 goto bad_area;
 115         if (expand_stack(vma, address))
 116                 goto bad_area;
 117 /*
 118  * Ok, we have a good vm_area for this memory access, so
 119  * we can handle it..
 120  */
 121 good_area:
 122         si_code = SEGV_ACCERR;
 123         if (writeaccess) {
 124                 if (!(vma->vm_flags & VM_WRITE))
 125                         goto bad_area;
 126         } else {
 127                 if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
 128                         goto bad_area;
 129         }
 130
 131         /*
 132          * If for any reason at all we couldn't handle the fault,
 133          * make sure we exit gracefully rather than endlessly redo
 134          * the fault.
 135          */
 136 survive:
 137         fault = handle_mm_fault(mm, vma, address, writeaccess);
 138         if (unlikely(fault & VM_FAULT_ERROR)) {
 139                 if (fault & VM_FAULT_OOM)
 140                         goto out_of_memory;
 141                 else if (fault & VM_FAULT_SIGBUS)
 142                         goto do_sigbus;
 143                 BUG();
 144         }
 145         if (fault & VM_FAULT_MAJOR)
 146                 tsk->maj_flt++;
 147         else
 148                 tsk->min_flt++;
 149
 150         up_read(&mm->mmap_sem);
 151         return;
 152
 153 /*
 154  * Something tried to access memory that isn't in our memory map..
 155  * Fix it, but check if it's kernel or user first..
 156  */
 157 bad_area:
 158         up_read(&mm->mmap_sem);
 159
 160 bad_area_nosemaphore:
 161         if (user_mode(regs)) {
 162                 info.si_signo = SIGSEGV;
 163                 info.si_errno = 0;
 164                 info.si_code = si_code;
 165                 info.si_addr = (void *) address;
 166                 force_sig_info(SIGSEGV, &info, tsk);
 167                 return;
 168         }
 169
 170 no_context:
 171         /* Are we prepared to handle this kernel fault?  */
 172         if (fixup_exception(regs))
 173                 return;
 174
 175         if (handle_trapped_io(regs, address))
 176                 return;
 177 /*
 178  * Oops. The kernel tried to access some bad page. We'll have to
 179  * terminate things with extreme prejudice.
 180  *
 181  */
 182
 183         bust_spinlocks(1);
 184
 185         if (oops_may_print()) {
 186                 unsigned long page;
 187
 188                 if (address < PAGE_SIZE)
 189                         printk(KERN_ALERT "Unable to handle kernel NULL "
 190                                           "pointer dereference");
 191                 else
 192                         printk(KERN_ALERT "Unable to handle kernel paging "
 193                                           "request");
 194                 printk(" at virtual address %08lx\n", address);
 195                 printk(KERN_ALERT "pc = %08lx\n", regs->pc);
 196                 page = (unsigned long)get_TTB();
 197                 if (page) {
 198                         page = ((__typeof__(page) *)page)[address >> PGDIR_SHIFT];
 199                         printk(KERN_ALERT "*pde = %08lx\n", page);
 200                         if (page & _PAGE_PRESENT) {
 201                                 page &= PAGE_MASK;
 202                                 address &= 0x003ff000;
 203                                 page = ((__typeof__(page) *)
 204                                                 __va(page))[address >>
 205                                                             PAGE_SHIFT];
 206                                 printk(KERN_ALERT "*pte = %08lx\n", page);
 207                         }
 208                 }
 209         }
 210
 211         die("Oops", regs, writeaccess);
 212         bust_spinlocks(0);
 213         do_exit(SIGKILL);
 214
 215 /*
 216  * We ran out of memory, or some other thing happened to us that made
 217  * us unable to handle the page fault gracefully.
 218  */
 219 out_of_memory:
 220         up_read(&mm->mmap_sem);
 221         if (is_global_init(current)) {
 222                 yield();
 223                 down_read(&mm->mmap_sem);
 224                 goto survive;
 225         }
 226         printk("VM: killing process %s\n", tsk->comm);
 227         if (user_mode(regs))
 228                 do_group_exit(SIGKILL);
 229         goto no_context;
 230
 231 do_sigbus:
 232         up_read(&mm->mmap_sem);
 233
 234         /*
 235          * Send a sigbus, regardless of whether we were in kernel
 236          * or user mode.
 237          */
 238         info.si_signo = SIGBUS;
 239         info.si_errno = 0;
 240         info.si_code = BUS_ADRERR;
 241         info.si_addr = (void *)address;
 242         force_sig_info(SIGBUS, &info, tsk);
 243
 244         /* Kernel mode? Handle exceptions or die */
 245         if (!user_mode(regs))
 246                 goto no_context;
 247 }
 248
 249 static inline int notify_page_fault(struct pt_regs *regs, int trap)
 250 {
 251         int ret = 0;
 252
 253         trace_mark(kernel_arch_trap_entry, "trap_id %d ip #p%ld",
 254                    trap >> 5, instruction_pointer(regs));
 255
 256 #ifdef CONFIG_KPROBES
 257         if (!user_mode(regs)) {
 258                 preempt_disable();
 259                 if (kprobe_running() && kprobe_fault_handler(regs, trap))
 260                         ret = 1;
 261                 preempt_enable();
 262         }
 263 #endif
 264
 265         return ret;
 266 }
 267
 268 #ifdef CONFIG_SH_STORE_QUEUES
 269 /*
 270  * This is a special case for the SH-4 store queues, as pages for this
 271  * space still need to be faulted in before it's possible to flush the
 272  * store queue cache for writeout to the remapped region.
 273  */
 274 #define P3_ADDR_MAX             (P4SEG_STORE_QUE + 0x04000000)
 275 #else
 276 #define P3_ADDR_MAX             P4SEG
 277 #endif
 278
 279 /*
 280  * Called with interrupts disabled.
 281  */
 282 asmlinkage int __kprobes __do_page_fault(struct pt_regs *regs,
 283                                          unsigned long writeaccess,
 284                                          unsigned long address)
 285 {
 286         pgd_t *pgd;
 287         pud_t *pud;
 288         pmd_t *pmd;
 289         pte_t *pte;
 290         pte_t entry;
 291         int ret = 0;
 292
 293         if (notify_page_fault(regs, lookup_exception_vector()))
 294                 goto out;
 295
 296 #ifdef CONFIG_SH_KGDB
 297         if (kgdb_nofault && kgdb_bus_err_hook)
 298                 kgdb_bus_err_hook();
 299 #endif
 300
 301         ret = 1;
 302
 303         /*
 304          * We don't take page faults for P1, P2, and parts of P4, these
 305          * are always mapped, whether it be due to legacy behaviour in
 306          * 29-bit mode, or due to PMB configuration in 32-bit mode.
 307          */
 308         if (address >= P3SEG && address < P3_ADDR_MAX) {
 309                 pgd = pgd_offset_k(address);
 310         } else {
 311                 if (unlikely(address >= TASK_SIZE || !current->mm))
 312                         goto out;
 313
 314                 pgd = pgd_offset(current->mm, address);
 315         }
 316
 317         pud = pud_offset(pgd, address);
 318         if (pud_none_or_clear_bad(pud))
 319                 goto out;
 320         pmd = pmd_offset(pud, address);
 321         if (pmd_none_or_clear_bad(pmd))
 322                 goto out;
 323         pte = pte_offset_kernel(pmd, address);
 324         entry = *pte;
 325         if (unlikely(pte_none(entry) || pte_not_present(entry)))
 326                 goto out;
 327         if (unlikely(writeaccess && !pte_write(entry)))
 328                 goto out;
 329
 330         if (writeaccess)
 331                 entry = pte_mkdirty(entry);
 332         entry = pte_mkyoung(entry);
 333
 334 #if defined(CONFIG_CPU_SH4) && !defined(CONFIG_SMP)
 335         /*
 336          * ITLB is not affected by "ldtlb" instruction.
 337          * So, we need to flush the entry by ourselves.
 338          */
 339         local_flush_tlb_one(get_asid(), address & PAGE_MASK);
 340 #endif
 341
 342         set_pte(pte, entry);
 343         update_mmu_cache(NULL, address, entry);
 344
 345         ret = 0;
 346 out:
 347         trace_mark(kernel_arch_trap_exit, MARK_NOARGS);
 348         return ret;
 349 }