LXR linux/arch/sparc/mm/fault

   1/*
   2 * fault.c:  Page fault handlers for the Sparc.
   3 *
   4 * Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu)
   5 * Copyright (C) 1996 Eddie C. Dost (ecd@skynet.be)
   6 * Copyright (C) 1997 Jakub Jelinek (jj@sunsite.mff.cuni.cz)
   7 */
   8
   9#include <asm/head.h>
  10
  11#include <linux/string.h>
  12#include <linux/types.h>
  13#include <linux/sched.h>
  14#include <linux/ptrace.h>
  15#include <linux/mman.h>
  16#include <linux/threads.h>
  17#include <linux/kernel.h>
  18#include <linux/signal.h>
  19#include <linux/mm.h>
  20#include <linux/smp.h>
  21#include <linux/perf_event.h>
  22#include <linux/interrupt.h>
  23#include <linux/kdebug.h>
  24
  25#include <asm/page.h>
  26#include <asm/pgtable.h>
  27#include <asm/openprom.h>
  28#include <asm/oplib.h>
  29#include <asm/smp.h>
  30#include <asm/traps.h>
  31#include <asm/uaccess.h>
  32
  33int show_unhandled_signals = 1;
  34
  35static void unhandled_fault(unsigned long, struct task_struct *,
  36                struct pt_regs *) __attribute__ ((noreturn));
  37
  38static void __noreturn unhandled_fault(unsigned long address,
  39                                       struct task_struct *tsk,
  40                                       struct pt_regs *regs)
  41{
  42        if ((unsigned long) address < PAGE_SIZE) {
  43                printk(KERN_ALERT
  44                    "Unable to handle kernel NULL pointer dereference\n");
  45        } else {
  46                printk(KERN_ALERT "Unable to handle kernel paging request at virtual address %08lx\n",
  47                       address);
  48        }
  49        printk(KERN_ALERT "tsk->{mm,active_mm}->context = %08lx\n",
  50                (tsk->mm ? tsk->mm->context : tsk->active_mm->context));
  51        printk(KERN_ALERT "tsk->{mm,active_mm}->pgd = %08lx\n",
  52                (tsk->mm ? (unsigned long) tsk->mm->pgd :
  53                        (unsigned long) tsk->active_mm->pgd));
  54        die_if_kernel("Oops", regs);
  55}
  56
  57asmlinkage int lookup_fault(unsigned long pc, unsigned long ret_pc,
  58                            unsigned long address)
  59{
  60        struct pt_regs regs;
  61        unsigned long g2;
  62        unsigned int insn;
  63        int i;
  64
  65        i = search_extables_range(ret_pc, &g2);
  66        switch (i) {
  67        case 3:
  68                /* load & store will be handled by fixup */
  69                return 3;
  70
  71        case 1:
  72                /* store will be handled by fixup, load will bump out */
  73                /* for _to_ macros */
  74                insn = *((unsigned int *) pc);
  75                if ((insn >> 21) & 1)
  76                        return 1;
  77                break;
  78
  79        case 2:
  80                /* load will be handled by fixup, store will bump out */
  81                /* for _from_ macros */
  82                insn = *((unsigned int *) pc);
  83                if (!((insn >> 21) & 1) || ((insn>>19)&0x3f) == 15)
  84                        return 2;
  85                break;
  86
  87        default:
  88                break;
  89        }
  90
  91        memset(&regs, 0, sizeof(regs));
  92        regs.pc = pc;
  93        regs.npc = pc + 4;
  94        __asm__ __volatile__(
  95                "rd %%psr, %0\n\t"
  96                "nop\n\t"
  97                "nop\n\t"
  98                "nop\n" : "=r" (regs.psr));
  99        unhandled_fault(address, current, &regs);
 100
 101        /* Not reached */
 102        return 0;
 103}
 104
 105static inline void
 106show_signal_msg(struct pt_regs *regs, int sig, int code,
 107                unsigned long address, struct task_struct *tsk)
 108{
 109        if (!unhandled_signal(tsk, sig))
 110                return;
 111
 112        if (!printk_ratelimit())
 113                return;
 114
 115        printk("%s%s[%d]: segfault at %lx ip %p (rpc %p) sp %p error %x",
 116               task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
 117               tsk->comm, task_pid_nr(tsk), address,
 118               (void *)regs->pc, (void *)regs->u_regs[UREG_I7],
 119               (void *)regs->u_regs[UREG_FP], code);
 120
 121        print_vma_addr(KERN_CONT " in ", regs->pc);
 122
 123        printk(KERN_CONT "\n");
 124}
 125
 126static void __do_fault_siginfo(int code, int sig, struct pt_regs *regs,
 127                               unsigned long addr)
 128{
 129        siginfo_t info;
 130
 131        info.si_signo = sig;
 132        info.si_code = code;
 133        info.si_errno = 0;
 134        info.si_addr = (void __user *) addr;
 135        info.si_trapno = 0;
 136
 137        if (unlikely(show_unhandled_signals))
 138                show_signal_msg(regs, sig, info.si_code,
 139                                addr, current);
 140
 141        force_sig_info (sig, &info, current);
 142}
 143
 144extern unsigned long safe_compute_effective_address(struct pt_regs *,
 145                                                    unsigned int);
 146
 147static unsigned long compute_si_addr(struct pt_regs *regs, int text_fault)
 148{
 149        unsigned int insn;
 150
 151        if (text_fault)
 152                return regs->pc;
 153
 154        if (regs->psr & PSR_PS)
 155                insn = *(unsigned int *) regs->pc;
 156        else
 157                __get_user(insn, (unsigned int *) regs->pc);
 158
 159        return safe_compute_effective_address(regs, insn);
 160}
 161
 162static noinline void do_fault_siginfo(int code, int sig, struct pt_regs *regs,
 163                                      int text_fault)
 164{
 165        unsigned long addr = compute_si_addr(regs, text_fault);
 166
 167        __do_fault_siginfo(code, sig, regs, addr);
 168}
 169
 170asmlinkage void do_sparc_fault(struct pt_regs *regs, int text_fault, int write,
 171                               unsigned long address)
 172{
 173        struct vm_area_struct *vma;
 174        struct task_struct *tsk = current;
 175        struct mm_struct *mm = tsk->mm;
 176        unsigned int fixup;
 177        unsigned long g2;
 178        int from_user = !(regs->psr & PSR_PS);
 179        int fault, code;
 180        unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
 181
 182        if (text_fault)
 183                address = regs->pc;
 184
 185        /*
 186         * We fault-in kernel-space virtual memory on-demand. The
 187         * 'reference' page table is init_mm.pgd.
 188         *
 189         * NOTE! We MUST NOT take any locks for this case. We may
 190         * be in an interrupt or a critical region, and should
 191         * only copy the information from the master page table,
 192         * nothing more.
 193         */
 194        code = SEGV_MAPERR;
 195        if (address >= TASK_SIZE)
 196                goto vmalloc_fault;
 197
 198        /*
 199         * If we're in an interrupt or have no user
 200         * context, we must not take the fault..
 201         */
 202        if (in_atomic() || !mm)
 203                goto no_context;
 204
 205        perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
 206
 207retry:
 208        down_read(&mm->mmap_sem);
 209
 210        if (!from_user && address >= PAGE_OFFSET)
 211                goto bad_area;
 212
 213        vma = find_vma(mm, address);
 214        if (!vma)
 215                goto bad_area;
 216        if (vma->vm_start <= address)
 217                goto good_area;
 218        if (!(vma->vm_flags & VM_GROWSDOWN))
 219                goto bad_area;
 220        if (expand_stack(vma, address))
 221                goto bad_area;
 222        /*
 223         * Ok, we have a good vm_area for this memory access, so
 224         * we can handle it..
 225         */
 226good_area:
 227        code = SEGV_ACCERR;
 228        if (write) {
 229                if (!(vma->vm_flags & VM_WRITE))
 230                        goto bad_area;
 231        } else {
 232                /* Allow reads even for write-only mappings */
 233                if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
 234                        goto bad_area;
 235        }
 236
 237        if (from_user)
 238                flags |= FAULT_FLAG_USER;
 239        if (write)
 240                flags |= FAULT_FLAG_WRITE;
 241
 242        /*
 243         * If for any reason at all we couldn't handle the fault,
 244         * make sure we exit gracefully rather than endlessly redo
 245         * the fault.
 246         */
 247        fault = handle_mm_fault(mm, vma, address, flags);
 248
 249        if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
 250                return;
 251
 252        if (unlikely(fault & VM_FAULT_ERROR)) {
 253                if (fault & VM_FAULT_OOM)
 254                        goto out_of_memory;
 255                else if (fault & VM_FAULT_SIGBUS)
 256                        goto do_sigbus;
 257                BUG();
 258        }
 259
 260        if (flags & FAULT_FLAG_ALLOW_RETRY) {
 261                if (fault & VM_FAULT_MAJOR) {
 262                        current->maj_flt++;
 263                        perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ,
 264                                      1, regs, address);
 265                } else {
 266                        current->min_flt++;
 267                        perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN,
 268                                      1, regs, address);
 269                }
 270                if (fault & VM_FAULT_RETRY) {
 271                        flags &= ~FAULT_FLAG_ALLOW_RETRY;
 272                        flags |= FAULT_FLAG_TRIED;
 273
 274                        /* No need to up_read(&mm->mmap_sem) as we would
 275                         * have already released it in __lock_page_or_retry
 276                         * in mm/filemap.c.
 277                         */
 278
 279                        goto retry;
 280                }
 281        }
 282
 283        up_read(&mm->mmap_sem);
 284        return;
 285
 286        /*
 287         * Something tried to access memory that isn't in our memory map..
 288         * Fix it, but check if it's kernel or user first..
 289         */
 290bad_area:
 291        up_read(&mm->mmap_sem);
 292
 293bad_area_nosemaphore:
 294        /* User mode accesses just cause a SIGSEGV */
 295        if (from_user) {
 296                do_fault_siginfo(code, SIGSEGV, regs, text_fault);
 297                return;
 298        }
 299
 300        /* Is this in ex_table? */
 301no_context:
 302        g2 = regs->u_regs[UREG_G2];
 303        if (!from_user) {
 304                fixup = search_extables_range(regs->pc, &g2);
 305                /* Values below 10 are reserved for other things */
 306                if (fixup > 10) {
 307                        extern const unsigned __memset_start[];
 308                        extern const unsigned __memset_end[];
 309                        extern const unsigned __csum_partial_copy_start[];
 310                        extern const unsigned __csum_partial_copy_end[];
 311
 312#ifdef DEBUG_EXCEPTIONS
 313                        printk("Exception: PC<%08lx> faddr<%08lx>\n",
 314                               regs->pc, address);
 315                        printk("EX_TABLE: insn<%08lx> fixup<%08x> g2<%08lx>\n",
 316                                regs->pc, fixup, g2);
 317#endif
 318                        if ((regs->pc >= (unsigned long)__memset_start &&
 319                             regs->pc < (unsigned long)__memset_end) ||
 320                            (regs->pc >= (unsigned long)__csum_partial_copy_start &&
 321                             regs->pc < (unsigned long)__csum_partial_copy_end)) {
 322                                regs->u_regs[UREG_I4] = address;
 323                                regs->u_regs[UREG_I5] = regs->pc;
 324                        }
 325                        regs->u_regs[UREG_G2] = g2;
 326                        regs->pc = fixup;
 327                        regs->npc = regs->pc + 4;
 328                        return;
 329                }
 330        }
 331
 332        unhandled_fault(address, tsk, regs);
 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 */
 339out_of_memory:
 340        up_read(&mm->mmap_sem);
 341        if (from_user) {
 342                pagefault_out_of_memory();
 343                return;
 344        }
 345        goto no_context;
 346
 347do_sigbus:
 348        up_read(&mm->mmap_sem);
 349        do_fault_siginfo(BUS_ADRERR, SIGBUS, regs, text_fault);
 350        if (!from_user)
 351                goto no_context;
 352
 353vmalloc_fault:
 354        {
 355                /*
 356                 * Synchronize this task's top level page-table
 357                 * with the 'reference' page table.
 358                 */
 359                int offset = pgd_index(address);
 360                pgd_t *pgd, *pgd_k;
 361                pmd_t *pmd, *pmd_k;
 362
 363                pgd = tsk->active_mm->pgd + offset;
 364                pgd_k = init_mm.pgd + offset;
 365
 366                if (!pgd_present(*pgd)) {
 367                        if (!pgd_present(*pgd_k))
 368                                goto bad_area_nosemaphore;
 369                        pgd_val(*pgd) = pgd_val(*pgd_k);
 370                        return;
 371                }
 372
 373                pmd = pmd_offset(pgd, address);
 374                pmd_k = pmd_offset(pgd_k, address);
 375
 376                if (pmd_present(*pmd) || !pmd_present(*pmd_k))
 377                        goto bad_area_nosemaphore;
 378
 379                *pmd = *pmd_k;
 380                return;
 381        }
 382}
 383
 384/* This always deals with user addresses. */
 385static void force_user_fault(unsigned long address, int write)
 386{
 387        struct vm_area_struct *vma;
 388        struct task_struct *tsk = current;
 389        struct mm_struct *mm = tsk->mm;
 390        unsigned int flags = FAULT_FLAG_USER;
 391        int code;
 392
 393        code = SEGV_MAPERR;
 394
 395        down_read(&mm->mmap_sem);
 396        vma = find_vma(mm, address);
 397        if (!vma)
 398                goto bad_area;
 399        if (vma->vm_start <= address)
 400                goto good_area;
 401        if (!(vma->vm_flags & VM_GROWSDOWN))
 402                goto bad_area;
 403        if (expand_stack(vma, address))
 404                goto bad_area;
 405good_area:
 406        code = SEGV_ACCERR;
 407        if (write) {
 408                if (!(vma->vm_flags & VM_WRITE))
 409                        goto bad_area;
 410                flags |= FAULT_FLAG_WRITE;
 411        } else {
 412                if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
 413                        goto bad_area;
 414        }
 415        switch (handle_mm_fault(mm, vma, address, flags)) {
 416        case VM_FAULT_SIGBUS:
 417        case VM_FAULT_OOM:
 418                goto do_sigbus;
 419        }
 420        up_read(&mm->mmap_sem);
 421        return;
 422bad_area:
 423        up_read(&mm->mmap_sem);
 424        __do_fault_siginfo(code, SIGSEGV, tsk->thread.kregs, address);
 425        return;
 426
 427do_sigbus:
 428        up_read(&mm->mmap_sem);
 429        __do_fault_siginfo(BUS_ADRERR, SIGBUS, tsk->thread.kregs, address);
 430}
 431
 432static void check_stack_aligned(unsigned long sp)
 433{
 434        if (sp & 0x7UL)
 435                force_sig(SIGILL, current);
 436}
 437
 438void window_overflow_fault(void)
 439{
 440        unsigned long sp;
 441
 442        sp = current_thread_info()->rwbuf_stkptrs[0];
 443        if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
 444                force_user_fault(sp + 0x38, 1);
 445        force_user_fault(sp, 1);
 446
 447        check_stack_aligned(sp);
 448}
 449
 450void window_underflow_fault(unsigned long sp)
 451{
 452        if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
 453                force_user_fault(sp + 0x38, 0);
 454        force_user_fault(sp, 0);
 455
 456        check_stack_aligned(sp);
 457}
 458
 459void window_ret_fault(struct pt_regs *regs)
 460{
 461        unsigned long sp;
 462
 463        sp = regs->u_regs[UREG_FP];
 464        if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
 465                force_user_fault(sp + 0x38, 0);
 466        force_user_fault(sp, 0);
 467
 468        check_stack_aligned(sp);
 469}
 470