arch/mn10300/mm/fault.c

   1 /* MN10300 MMU Fault handler
   2  *
   3  * Copyright (C) 2007 Matsushita Electric Industrial Co., Ltd.
   4  * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
   5  * Modified by David Howells (dhowells@redhat.com)
   6  *
   7  * This program is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU General Public Licence
   9  * as published by the Free Software Foundation; either version
  10  * 2 of the Licence, or (at your option) any later version.
  11  */
  12
  13 #include <linux/signal.h>
  14 #include <linux/sched.h>
  15 #include <linux/kernel.h>
  16 #include <linux/errno.h>
  17 #include <linux/string.h>
  18 #include <linux/types.h>
  19 #include <linux/ptrace.h>
  20 #include <linux/mman.h>
  21 #include <linux/mm.h>
  22 #include <linux/smp.h>
  23 #include <linux/smp_lock.h>
  24 #include <linux/interrupt.h>
  25 #include <linux/init.h>
  26 #include <linux/vt_kern.h>              /* For unblank_screen() */
  27
  28 #include <asm/system.h>
  29 #include <asm/uaccess.h>
  30 #include <asm/pgalloc.h>
  31 #include <asm/hardirq.h>
  32 #include <asm/gdb-stub.h>
  33 #include <asm/cpu-regs.h>
  34
  35 /*
  36  * Unlock any spinlocks which will prevent us from getting the
  37  * message out
  38  */
  39 void bust_spinlocks(int yes)
  40 {
  41         if (yes) {
  42                 oops_in_progress = 1;
  43 #ifdef CONFIG_SMP
  44                 /* Many serial drivers do __global_cli() */
  45                 global_irq_lock = 0;
  46 #endif
  47         } else {
  48                 int loglevel_save = console_loglevel;
  49 #ifdef CONFIG_VT
  50                 unblank_screen();
  51 #endif
  52                 oops_in_progress = 0;
  53                 /*
  54                  * OK, the message is on the console.  Now we call printk()
  55                  * without oops_in_progress set so that printk will give klogd
  56                  * a poke.  Hold onto your hats...
  57                  */
  58                 console_loglevel = 15;  /* NMI oopser may have shut the console
  59                                          * up */
  60                 printk(" ");
  61                 console_loglevel = loglevel_save;
  62         }
  63 }
  64
  65 void do_BUG(const char *file, int line)
  66 {
  67         bust_spinlocks(1);
  68         printk(KERN_EMERG "------------[ cut here ]------------\n");
  69         printk(KERN_EMERG "kernel BUG at %s:%d!\n", file, line);
  70 }
  71
  72 #if 0
  73 static void print_pagetable_entries(pgd_t *pgdir, unsigned long address)
  74 {
  75         pgd_t *pgd;
  76         pmd_t *pmd;
  77         pte_t *pte;
  78
  79         pgd = pgdir + __pgd_offset(address);
  80         printk(KERN_DEBUG "pgd entry %p: %016Lx\n",
  81                pgd, (long long) pgd_val(*pgd));
  82
  83         if (!pgd_present(*pgd)) {
  84                 printk(KERN_DEBUG "... pgd not present!\n");
  85                 return;
  86         }
  87         pmd = pmd_offset(pgd, address);
  88         printk(KERN_DEBUG "pmd entry %p: %016Lx\n",
  89                pmd, (long long)pmd_val(*pmd));
  90
  91         if (!pmd_present(*pmd)) {
  92                 printk(KERN_DEBUG "... pmd not present!\n");
  93                 return;
  94         }
  95         pte = pte_offset(pmd, address);
  96         printk(KERN_DEBUG "pte entry %p: %016Lx\n",
  97                pte, (long long) pte_val(*pte));
  98
  99         if (!pte_present(*pte))
 100                 printk(KERN_DEBUG "... pte not present!\n");
 101 }
 102 #endif
 103
 104 asmlinkage void monitor_signal(struct pt_regs *);
 105
 106 /*
 107  * This routine handles page faults.  It determines the address,
 108  * and the problem, and then passes it off to one of the appropriate
 109  * routines.
 110  *
 111  * fault_code:
 112  * - LSW: either MMUFCR_IFC or MMUFCR_DFC as appropriate
 113  * - MSW: 0 if data access, 1 if instruction access
 114  * - bit 0: TLB miss flag
 115  * - bit 1: initial write
 116  * - bit 2: page invalid
 117  * - bit 3: protection violation
 118  * - bit 4: accessor (0=user 1=kernel)
 119  * - bit 5: 0=read 1=write
 120  * - bit 6-8: page protection spec
 121  * - bit 9: illegal address
 122  * - bit 16: 0=data 1=ins
 123  *
 124  */
 125 asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long fault_code,
 126                               unsigned long address)
 127 {
 128         struct vm_area_struct *vma;
 129         struct task_struct *tsk;
 130         struct mm_struct *mm;
 131         unsigned long page;
 132         siginfo_t info;
 133         int write, fault;
 134
 135 #ifdef CONFIG_GDBSTUB
 136         /* handle GDB stub causing a fault */
 137         if (gdbstub_busy) {
 138                 gdbstub_exception(regs, TBR & TBR_INT_CODE);
 139                 return;
 140         }
 141 #endif
 142
 143 #if 0
 144         printk(KERN_DEBUG "--- do_page_fault(%p,%s:%04lx,%08lx)\n",
 145                regs,
 146                fault_code & 0x10000 ? "ins" : "data",
 147                fault_code & 0xffff, address);
 148 #endif
 149
 150         tsk = current;
 151
 152         /*
 153          * We fault-in kernel-space virtual memory on-demand. The
 154          * 'reference' page table is init_mm.pgd.
 155          *
 156          * NOTE! We MUST NOT take any locks for this case. We may
 157          * be in an interrupt or a critical region, and should
 158          * only copy the information from the master page table,
 159          * nothing more.
 160          *
 161          * This verifies that the fault happens in kernel space
 162          * and that the fault was a page not present (invalid) error
 163          */
 164         if (address >= VMALLOC_START && address < VMALLOC_END &&
 165             (fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_SR &&
 166             (fault_code & MMUFCR_xFC_PGINVAL) == MMUFCR_xFC_PGINVAL
 167             )
 168                 goto vmalloc_fault;
 169
 170         mm = tsk->mm;
 171         info.si_code = SEGV_MAPERR;
 172
 173         /*
 174          * If we're in an interrupt or have no user
 175          * context, we must not take the fault..
 176          */
 177         if (in_interrupt() || !mm)
 178                 goto no_context;
 179
 180         down_read(&mm->mmap_sem);
 181
 182         vma = find_vma(mm, address);
 183         if (!vma)
 184                 goto bad_area;
 185         if (vma->vm_start <= address)
 186                 goto good_area;
 187         if (!(vma->vm_flags & VM_GROWSDOWN))
 188                 goto bad_area;
 189
 190         if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_USR) {
 191                 /* accessing the stack below the stack pointer is always a
 192                  * bug */
 193                 if ((address & PAGE_MASK) + 2 * PAGE_SIZE < regs->sp) {
 194 #if 0
 195                         printk(KERN_WARNING
 196                                "[%d] ### Access below stack @%lx (sp=%lx)\n",
 197                                current->pid, address, regs->sp);
 198                         printk(KERN_WARNING
 199                                "vma [%08x - %08x]\n",
 200                                vma->vm_start, vma->vm_end);
 201                         show_registers(regs);
 202                         printk(KERN_WARNING
 203                                "[%d] ### Code: [%08lx]"
 204                                " %02x %02x %02x %02x %02x %02x %02x %02x\n",
 205                                current->pid,
 206                                regs->pc,
 207                                ((u8 *) regs->pc)[0],
 208                                ((u8 *) regs->pc)[1],
 209                                ((u8 *) regs->pc)[2],
 210                                ((u8 *) regs->pc)[3],
 211                                ((u8 *) regs->pc)[4],
 212                                ((u8 *) regs->pc)[5],
 213                                ((u8 *) regs->pc)[6],
 214                                ((u8 *) regs->pc)[7]
 215                                );
 216 #endif
 217                         goto bad_area;
 218                 }
 219         }
 220
 221         if (expand_stack(vma, address))
 222                 goto bad_area;
 223
 224 /*
 225  * Ok, we have a good vm_area for this memory access, so
 226  * we can handle it..
 227  */
 228 good_area:
 229         info.si_code = SEGV_ACCERR;
 230         write = 0;
 231         switch (fault_code & (MMUFCR_xFC_PGINVAL|MMUFCR_xFC_TYPE)) {
 232         default:        /* 3: write, present */
 233         case MMUFCR_xFC_TYPE_WRITE:
 234 #ifdef TEST_VERIFY_AREA
 235                 if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_SR)
 236                         printk(KERN_DEBUG "WP fault at %08lx\n", regs->pc);
 237 #endif
 238                 /* write to absent page */
 239         case MMUFCR_xFC_PGINVAL | MMUFCR_xFC_TYPE_WRITE:
 240                 if (!(vma->vm_flags & VM_WRITE))
 241                         goto bad_area;
 242                 write++;
 243                 break;
 244
 245                 /* read from protected page */
 246         case MMUFCR_xFC_TYPE_READ:
 247                 goto bad_area;
 248
 249                 /* read from absent page present */
 250         case MMUFCR_xFC_PGINVAL | MMUFCR_xFC_TYPE_READ:
 251                 if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
 252                         goto bad_area;
 253                 break;
 254         }
 255
 256         /*
 257          * If for any reason at all we couldn't handle the fault,
 258          * make sure we exit gracefully rather than endlessly redo
 259          * the fault.
 260          */
 261         fault = handle_mm_fault(mm, vma, address, write);
 262         if (unlikely(fault & VM_FAULT_ERROR)) {
 263                 if (fault & VM_FAULT_OOM)
 264                         goto out_of_memory;
 265                 else if (fault & VM_FAULT_SIGBUS)
 266                         goto do_sigbus;
 267                 BUG();
 268         }
 269         if (fault & VM_FAULT_MAJOR)
 270                 current->maj_flt++;
 271         else
 272                 current->min_flt++;
 273
 274         up_read(&mm->mmap_sem);
 275         return;
 276
 277 /*
 278  * Something tried to access memory that isn't in our memory map..
 279  * Fix it, but check if it's kernel or user first..
 280  */
 281 bad_area:
 282         up_read(&mm->mmap_sem);
 283         monitor_signal(regs);
 284
 285         /* User mode accesses just cause a SIGSEGV */
 286         if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_USR) {
 287                 info.si_signo = SIGSEGV;
 288                 info.si_errno = 0;
 289                 /* info.si_code has been set above */
 290                 info.si_addr = (void *)address;
 291                 force_sig_info(SIGSEGV, &info, tsk);
 292                 return;
 293         }
 294
 295 no_context:
 296         monitor_signal(regs);
 297         /* Are we prepared to handle this kernel fault?  */
 298         if (fixup_exception(regs))
 299                 return;
 300
 301 /*
 302  * Oops. The kernel tried to access some bad page. We'll have to
 303  * terminate things with extreme prejudice.
 304  */
 305
 306         bust_spinlocks(1);
 307
 308         if (address < PAGE_SIZE)
 309                 printk(KERN_ALERT
 310                        "Unable to handle kernel NULL pointer dereference");
 311         else
 312                 printk(KERN_ALERT
 313                        "Unable to handle kernel paging request");
 314         printk(" at virtual address %08lx\n", address);
 315         printk(" printing pc:\n");
 316         printk(KERN_ALERT "%08lx\n", regs->pc);
 317
 318 #ifdef CONFIG_GDBSTUB
 319         gdbstub_intercept(
 320                 regs, fault_code & 0x00010000 ? EXCEP_IAERROR : EXCEP_DAERROR);
 321 #endif
 322
 323         page = PTBR;
 324         page = ((unsigned long *) __va(page))[address >> 22];
 325         printk(KERN_ALERT "*pde = %08lx\n", page);
 326         if (page & 1) {
 327                 page &= PAGE_MASK;
 328                 address &= 0x003ff000;
 329                 page = ((unsigned long *) __va(page))[address >> PAGE_SHIFT];
 330                 printk(KERN_ALERT "*pte = %08lx\n", page);
 331         }
 332
 333         die("Oops", regs, fault_code);
 334         do_exit(SIGKILL);
 335
 336 /*
 337  * We ran out of memory, or some other thing happened to us that made
 338  * us unable to handle the page fault gracefully.
 339  */
 340 out_of_memory:
 341         up_read(&mm->mmap_sem);
 342         monitor_signal(regs);
 343         printk(KERN_ALERT "VM: killing process %s\n", tsk->comm);
 344         if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_USR)
 345                 do_exit(SIGKILL);
 346         goto no_context;
 347
 348 do_sigbus:
 349         up_read(&mm->mmap_sem);
 350         monitor_signal(regs);
 351
 352         /*
 353          * Send a sigbus, regardless of whether we were in kernel
 354          * or user mode.
 355          */
 356         info.si_signo = SIGBUS;
 357         info.si_errno = 0;
 358         info.si_code = BUS_ADRERR;
 359         info.si_addr = (void *)address;
 360         force_sig_info(SIGBUS, &info, tsk);
 361
 362         /* Kernel mode? Handle exceptions or die */
 363         if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_SR)
 364                 goto no_context;
 365         return;
 366
 367 vmalloc_fault:
 368         {
 369                 /*
 370                  * Synchronize this task's top level page-table
 371                  * with the 'reference' page table.
 372                  *
 373                  * Do _not_ use "tsk" here. We might be inside
 374                  * an interrupt in the middle of a task switch..
 375                  */
 376                 int index = pgd_index(address);
 377                 pgd_t *pgd, *pgd_k;
 378                 pud_t *pud, *pud_k;
 379                 pmd_t *pmd, *pmd_k;
 380                 pte_t *pte_k;
 381
 382                 pgd_k = init_mm.pgd + index;
 383
 384                 if (!pgd_present(*pgd_k))
 385                         goto no_context;
 386
 387                 pud_k = pud_offset(pgd_k, address);
 388                 if (!pud_present(*pud_k))
 389                         goto no_context;
 390
 391                 pmd_k = pmd_offset(pud_k, address);
 392                 if (!pmd_present(*pmd_k))
 393                         goto no_context;
 394
 395                 pgd = (pgd_t *) PTBR + index;
 396                 pud = pud_offset(pgd, address);
 397                 pmd = pmd_offset(pud, address);
 398                 set_pmd(pmd, *pmd_k);
 399
 400                 pte_k = pte_offset_kernel(pmd_k, address);
 401                 if (!pte_present(*pte_k))
 402                         goto no_context;
 403                 return;
 404         }
 405 }