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