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#include <linux/uaccess.h>
  25
  26#include <asm/page.h>
  27#include <asm/pgtable.h>
  28#include <asm/openprom.h>
  29#include <asm/oplib.h>
  30#include <asm/setup.h>
  31#include <asm/smp.h>
  32#include <asm/traps.h>
  33
  34#include "mm_32.h"
  35
  36int show_unhandled_signals = 1;
  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
 144static unsigned long compute_si_addr(struct pt_regs *regs, int text_fault)
 145{
 146        unsigned int insn;
 147
 148        if (text_fault)
 149                return regs->pc;
 150
 151        if (regs->psr & PSR_PS)
 152                insn = *(unsigned int *) regs->pc;
 153        else
 154                __get_user(insn, (unsigned int *) regs->pc);
 155
 156        return safe_compute_effective_address(regs, insn);
 157}
 158
 159static noinline void do_fault_siginfo(int code, int sig, struct pt_regs *regs,
 160                                      int text_fault)
 161{
 162        unsigned long addr = compute_si_addr(regs, text_fault);
 163
 164        __do_fault_siginfo(code, sig, regs, addr);
 165}
 166
 167asmlinkage void do_sparc_fault(struct pt_regs *regs, int text_fault, int write,
 168                               unsigned long address)
 169{
 170        struct vm_area_struct *vma;
 171        struct task_struct *tsk = current;
 172        struct mm_struct *mm = tsk->mm;
 173        unsigned int fixup;
 174        unsigned long g2;
 175        int from_user = !(regs->psr & PSR_PS);
 176        int fault, code;
 177        unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
 178
 179        if (text_fault)
 180                address = regs->pc;
 181
 182        /*
 183         * We fault-in kernel-space virtual memory on-demand. The
 184         * 'reference' page table is init_mm.pgd.
 185         *
 186         * NOTE! We MUST NOT take any locks for this case. We may
 187         * be in an interrupt or a critical region, and should
 188         * only copy the information from the master page table,
 189         * nothing more.
 190         */
 191        code = SEGV_MAPERR;
 192        if (address >= TASK_SIZE)
 193                goto vmalloc_fault;
 194
 195        /*
 196         * If we're in an interrupt or have no user
 197         * context, we must not take the fault..
 198         */
 199        if (pagefault_disabled() || !mm)
 200                goto no_context;
 201
 202        perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
 203
 204retry:
 205        down_read(&mm->mmap_sem);
 206
 207        if (!from_user && address >= PAGE_OFFSET)
 208                goto bad_area;
 209
 210        vma = find_vma(mm, address);
 211        if (!vma)
 212                goto bad_area;
 213        if (vma->vm_start <= address)
 214                goto good_area;
 215        if (!(vma->vm_flags & VM_GROWSDOWN))
 216                goto bad_area;
 217        if (expand_stack(vma, address))
 218                goto bad_area;
 219        /*
 220         * Ok, we have a good vm_area for this memory access, so
 221         * we can handle it..
 222         */
 223good_area:
 224        code = SEGV_ACCERR;
 225        if (write) {
 226                if (!(vma->vm_flags & VM_WRITE))
 227                        goto bad_area;
 228        } else {
 229                /* Allow reads even for write-only mappings */
 230                if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
 231                        goto bad_area;
 232        }
 233
 234        if (from_user)
 235                flags |= FAULT_FLAG_USER;
 236        if (write)
 237                flags |= FAULT_FLAG_WRITE;
 238
 239        /*
 240         * If for any reason at all we couldn't handle the fault,
 241         * make sure we exit gracefully rather than endlessly redo
 242         * the fault.
 243         */
 244        fault = handle_mm_fault(mm, vma, address, flags);
 245
 246        if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
 247                return;
 248
 249        if (unlikely(fault & VM_FAULT_ERROR)) {
 250                if (fault & VM_FAULT_OOM)
 251                        goto out_of_memory;
 252                else if (fault & VM_FAULT_SIGSEGV)
 253                        goto bad_area;
 254                else if (fault & VM_FAULT_SIGBUS)
 255                        goto do_sigbus;
 256                BUG();
 257        }
 258
 259        if (flags & FAULT_FLAG_ALLOW_RETRY) {
 260                if (fault & VM_FAULT_MAJOR) {
 261                        current->maj_flt++;
 262                        perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ,
 263                                      1, regs, address);
 264                } else {
 265                        current->min_flt++;
 266                        perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN,
 267                                      1, regs, address);
 268                }
 269                if (fault & VM_FAULT_RETRY) {
 270                        flags &= ~FAULT_FLAG_ALLOW_RETRY;
 271                        flags |= FAULT_FLAG_TRIED;
 272
 273                        /* No need to up_read(&mm->mmap_sem) as we would
 274                         * have already released it in __lock_page_or_retry
 275                         * in mm/filemap.c.
 276                         */
 277
 278                        goto retry;
 279                }
 280        }
 281
 282        up_read(&mm->mmap_sem);
 283        return;
 284
 285        /*
 286         * Something tried to access memory that isn't in our memory map..
 287         * Fix it, but check if it's kernel or user first..
 288         */
 289bad_area:
 290        up_read(&mm->mmap_sem);
 291
 292bad_area_nosemaphore:
 293        /* User mode accesses just cause a SIGSEGV */
 294        if (from_user) {
 295                do_fault_siginfo(code, SIGSEGV, regs, text_fault);
 296                return;
 297        }
 298
 299        /* Is this in ex_table? */
 300no_context:
 301        g2 = regs->u_regs[UREG_G2];
 302        if (!from_user) {
 303                fixup = search_extables_range(regs->pc, &g2);
 304                /* Values below 10 are reserved for other things */
 305                if (fixup > 10) {
 306                        extern const unsigned __memset_start[];
 307                        extern const unsigned __memset_end[];
 308                        extern const unsigned __csum_partial_copy_start[];
 309                        extern const unsigned __csum_partial_copy_end[];
 310
 311#ifdef DEBUG_EXCEPTIONS
 312                        printk("Exception: PC<%08lx> faddr<%08lx>\n",
 313                               regs->pc, address);
 314                        printk("EX_TABLE: insn<%08lx> fixup<%08x> g2<%08lx>\n",
 315                                regs->pc, fixup, g2);
 316#endif
 317                        if ((regs->pc >= (unsigned long)__memset_start &&
 318                             regs->pc < (unsigned long)__memset_end) ||
 319                            (regs->pc >= (unsigned long)__csum_partial_copy_start &&
 320                             regs->pc < (unsigned long)__csum_partial_copy_end)) {
 321                                regs->u_regs[UREG_I4] = address;
 322                                regs->u_regs[UREG_I5] = regs->pc;
 323                        }
 324                        regs->u_regs[UREG_G2] = g2;
 325                        regs->pc = fixup;
 326                        regs->npc = regs->pc + 4;
 327                        return;
 328                }
 329        }
 330
 331        unhandled_fault(address, tsk, regs);
 332        do_exit(SIGKILL);
 333
 334/*
 335 * We ran out of memory, or some other thing happened to us that made
 336 * us unable to handle the page fault gracefully.
 337 */
 338out_of_memory:
 339        up_read(&mm->mmap_sem);
 340        if (from_user) {
 341                pagefault_out_of_memory();
 342                return;
 343        }
 344        goto no_context;
 345
 346do_sigbus:
 347        up_read(&mm->mmap_sem);
 348        do_fault_siginfo(BUS_ADRERR, SIGBUS, regs, text_fault);
 349        if (!from_user)
 350                goto no_context;
 351
 352vmalloc_fault:
 353        {
 354                /*
 355                 * Synchronize this task's top level page-table
 356                 * with the 'reference' page table.
 357                 */
 358                int offset = pgd_index(address);
 359                pgd_t *pgd, *pgd_k;
 360                pmd_t *pmd, *pmd_k;
 361
 362                pgd = tsk->active_mm->pgd + offset;
 363                pgd_k = init_mm.pgd + offset;
 364
 365                if (!pgd_present(*pgd)) {
 366                        if (!pgd_present(*pgd_k))
 367                                goto bad_area_nosemaphore;
 368                        pgd_val(*pgd) = pgd_val(*pgd_k);
 369                        return;
 370                }
 371
 372                pmd = pmd_offset(pgd, address);
 373                pmd_k = pmd_offset(pgd_k, address);
 374
 375                if (pmd_present(*pmd) || !pmd_present(*pmd_k))
 376                        goto bad_area_nosemaphore;
 377
 378                *pmd = *pmd_k;
 379                return;
 380        }
 381}
 382
 383/* This always deals with user addresses. */
 384static void force_user_fault(unsigned long address, int write)
 385{
 386        struct vm_area_struct *vma;
 387        struct task_struct *tsk = current;
 388        struct mm_struct *mm = tsk->mm;
 389        unsigned int flags = FAULT_FLAG_USER;
 390        int code;
 391
 392        code = SEGV_MAPERR;
 393
 394        down_read(&mm->mmap_sem);
 395        vma = find_vma(mm, address);
 396        if (!vma)
 397                goto bad_area;
 398        if (vma->vm_start <= address)
 399                goto good_area;
 400        if (!(vma->vm_flags & VM_GROWSDOWN))
 401                goto bad_area;
 402        if (expand_stack(vma, address))
 403                goto bad_area;
 404good_area:
 405        code = SEGV_ACCERR;
 406        if (write) {
 407                if (!(vma->vm_flags & VM_WRITE))
 408                        goto bad_area;
 409                flags |= FAULT_FLAG_WRITE;
 410        } else {
 411                if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
 412                        goto bad_area;
 413        }
 414        switch (handle_mm_fault(mm, vma, address, flags)) {
 415        case VM_FAULT_SIGBUS:
 416        case VM_FAULT_OOM:
 417                goto do_sigbus;
 418        }
 419        up_read(&mm->mmap_sem);
 420        return;
 421bad_area:
 422        up_read(&mm->mmap_sem);
 423        __do_fault_siginfo(code, SIGSEGV, tsk->thread.kregs, address);
 424        return;
 425
 426do_sigbus:
 427        up_read(&mm->mmap_sem);
 428        __do_fault_siginfo(BUS_ADRERR, SIGBUS, tsk->thread.kregs, address);
 429}
 430
 431static void check_stack_aligned(unsigned long sp)
 432{
 433        if (sp & 0x7UL)
 434                force_sig(SIGILL, current);
 435}
 436
 437void window_overflow_fault(void)
 438{
 439        unsigned long sp;
 440
 441        sp = current_thread_info()->rwbuf_stkptrs[0];
 442        if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
 443                force_user_fault(sp + 0x38, 1);
 444        force_user_fault(sp, 1);
 445
 446        check_stack_aligned(sp);
 447}
 448
 449void window_underflow_fault(unsigned long sp)
 450{
 451        if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
 452                force_user_fault(sp + 0x38, 0);
 453        force_user_fault(sp, 0);
 454
 455        check_stack_aligned(sp);
 456}
 457
 458void window_ret_fault(struct pt_regs *regs)
 459{
 460        unsigned long sp;
 461
 462        sp = regs->u_regs[UREG_FP];
 463        if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
 464                force_user_fault(sp + 0x38, 0);
 465        force_user_fault(sp, 0);
 466
 467        check_stack_aligned(sp);
 468}
 469