arch/x86/kernel/traps.c

   1 /*
   2  *  Copyright (C) 1991, 1992  Linus Torvalds
   3  *  Copyright (C) 2000, 2001, 2002 Andi Kleen, SuSE Labs
   4  *
   5  *  Pentium III FXSR, SSE support
   6  *      Gareth Hughes <gareth@valinux.com>, May 2000
   7  */
   8
   9 /*
  10  * Handle hardware traps and faults.
  11  */
  12
  13 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  14
  15 #include <linux/interrupt.h>
  16 #include <linux/kallsyms.h>
  17 #include <linux/spinlock.h>
  18 #include <linux/kprobes.h>
  19 #include <linux/uaccess.h>
  20 #include <linux/kdebug.h>
  21 #include <linux/kgdb.h>
  22 #include <linux/kernel.h>
  23 #include <linux/module.h>
  24 #include <linux/ptrace.h>
  25 #include <linux/string.h>
  26 #include <linux/delay.h>
  27 #include <linux/errno.h>
  28 #include <linux/kexec.h>
  29 #include <linux/sched.h>
  30 #include <linux/timer.h>
  31 #include <linux/init.h>
  32 #include <linux/bug.h>
  33 #include <linux/nmi.h>
  34 #include <linux/mm.h>
  35 #include <linux/smp.h>
  36 #include <linux/io.h>
  37
  38 #ifdef CONFIG_EISA
  39 #include <linux/ioport.h>
  40 #include <linux/eisa.h>
  41 #endif
  42
  43 #if defined(CONFIG_EDAC)
  44 #include <linux/edac.h>
  45 #endif
  46
  47 #include <asm/kmemcheck.h>
  48 #include <asm/stacktrace.h>
  49 #include <asm/processor.h>
  50 #include <asm/debugreg.h>
  51 #include <linux/atomic.h>
  52 #include <asm/ftrace.h>
  53 #include <asm/traps.h>
  54 #include <asm/desc.h>
  55 #include <asm/i387.h>
  56 #include <asm/fpu-internal.h>
  57 #include <asm/mce.h>
  58 #include <asm/rcu.h>
  59
  60 #include <asm/mach_traps.h>
  61
  62 #ifdef CONFIG_X86_64
  63 #include <asm/x86_init.h>
  64 #include <asm/pgalloc.h>
  65 #include <asm/proto.h>
  66 #else
  67 #include <asm/processor-flags.h>
  68 #include <asm/setup.h>
  69
  70 asmlinkage int system_call(void);
  71
  72 /* Do we ignore FPU interrupts ? */
  73 char ignore_fpu_irq;
  74
  75 /*
  76  * The IDT has to be page-aligned to simplify the Pentium
  77  * F0 0F bug workaround.
  78  */
  79 gate_desc idt_table[NR_VECTORS] __page_aligned_data = { { { { 0, 0 } } }, };
  80 #endif
  81
  82 DECLARE_BITMAP(used_vectors, NR_VECTORS);
  83 EXPORT_SYMBOL_GPL(used_vectors);
  84
  85 static inline void conditional_sti(struct pt_regs *regs)
  86 {
  87         if (regs->flags & X86_EFLAGS_IF)
  88                 local_irq_enable();
  89 }
  90
  91 static inline void preempt_conditional_sti(struct pt_regs *regs)
  92 {
  93         inc_preempt_count();
  94         if (regs->flags & X86_EFLAGS_IF)
  95                 local_irq_enable();
  96 }
  97
  98 static inline void conditional_cli(struct pt_regs *regs)
  99 {
 100         if (regs->flags & X86_EFLAGS_IF)
 101                 local_irq_disable();
 102 }
 103
 104 static inline void preempt_conditional_cli(struct pt_regs *regs)
 105 {
 106         if (regs->flags & X86_EFLAGS_IF)
 107                 local_irq_disable();
 108         dec_preempt_count();
 109 }
 110
 111 static int __kprobes
 112 do_trap_no_signal(struct task_struct *tsk, int trapnr, char *str,
 113                   struct pt_regs *regs, long error_code)
 114 {
 115 #ifdef CONFIG_X86_32
 116         if (regs->flags & X86_VM_MASK) {
 117                 /*
 118                  * Traps 0, 1, 3, 4, and 5 should be forwarded to vm86.
 119                  * On nmi (interrupt 2), do_trap should not be called.
 120                  */
 121                 if (trapnr < X86_TRAP_UD) {
 122                         if (!handle_vm86_trap((struct kernel_vm86_regs *) regs,
 123                                                 error_code, trapnr))
 124                                 return 0;
 125                 }
 126                 return -1;
 127         }
 128 #endif
 129         if (!user_mode(regs)) {
 130                 if (!fixup_exception(regs)) {
 131                         tsk->thread.error_code = error_code;
 132                         tsk->thread.trap_nr = trapnr;
 133                         die(str, regs, error_code);
 134                 }
 135                 return 0;
 136         }
 137
 138         return -1;
 139 }
 140
 141 static void __kprobes
 142 do_trap(int trapnr, int signr, char *str, struct pt_regs *regs,
 143         long error_code, siginfo_t *info)
 144 {
 145         struct task_struct *tsk = current;
 146
 147
 148         if (!do_trap_no_signal(tsk, trapnr, str, regs, error_code))
 149                 return;
 150         /*
 151          * We want error_code and trap_nr set for userspace faults and
 152          * kernelspace faults which result in die(), but not
 153          * kernelspace faults which are fixed up.  die() gives the
 154          * process no chance to handle the signal and notice the
 155          * kernel fault information, so that won't result in polluting
 156          * the information about previously queued, but not yet
 157          * delivered, faults.  See also do_general_protection below.
 158          */
 159         tsk->thread.error_code = error_code;
 160         tsk->thread.trap_nr = trapnr;
 161
 162 #ifdef CONFIG_X86_64
 163         if (show_unhandled_signals && unhandled_signal(tsk, signr) &&
 164             printk_ratelimit()) {
 165                 pr_info("%s[%d] trap %s ip:%lx sp:%lx error:%lx",
 166                         tsk->comm, tsk->pid, str,
 167                         regs->ip, regs->sp, error_code);
 168                 print_vma_addr(" in ", regs->ip);
 169                 pr_cont("\n");
 170         }
 171 #endif
 172
 173         if (info)
 174                 force_sig_info(signr, info, tsk);
 175         else
 176                 force_sig(signr, tsk);
 177 }
 178
 179 #define DO_ERROR(trapnr, signr, str, name)                              \
 180 dotraplinkage void do_##name(struct pt_regs *regs, long error_code)     \
 181 {                                                                       \
 182         exception_enter(regs);                                          \
 183         if (notify_die(DIE_TRAP, str, regs, error_code,                 \
 184                         trapnr, signr) == NOTIFY_STOP) {                \
 185                 exception_exit(regs);                                   \
 186                 return;                                                 \
 187         }                                                               \
 188         conditional_sti(regs);                                          \
 189         do_trap(trapnr, signr, str, regs, error_code, NULL);            \
 190         exception_exit(regs);                                           \
 191 }
 192
 193 #define DO_ERROR_INFO(trapnr, signr, str, name, sicode, siaddr)         \
 194 dotraplinkage void do_##name(struct pt_regs *regs, long error_code)     \
 195 {                                                                       \
 196         siginfo_t info;                                                 \
 197         info.si_signo = signr;                                          \
 198         info.si_errno = 0;                                              \
 199         info.si_code = sicode;                                          \
 200         info.si_addr = (void __user *)siaddr;                           \
 201         exception_enter(regs);                                          \
 202         if (notify_die(DIE_TRAP, str, regs, error_code,                 \
 203                         trapnr, signr) == NOTIFY_STOP) {                \
 204                 exception_exit(regs);                                   \
 205                 return;                                                 \
 206         }                                                               \
 207         conditional_sti(regs);                                          \
 208         do_trap(trapnr, signr, str, regs, error_code, &info);           \
 209         exception_exit(regs);                                           \
 210 }
 211
 212 DO_ERROR_INFO(X86_TRAP_DE, SIGFPE, "divide error", divide_error, FPE_INTDIV,
 213                 regs->ip)
 214 DO_ERROR(X86_TRAP_OF, SIGSEGV, "overflow", overflow)
 215 DO_ERROR(X86_TRAP_BR, SIGSEGV, "bounds", bounds)
 216 DO_ERROR_INFO(X86_TRAP_UD, SIGILL, "invalid opcode", invalid_op, ILL_ILLOPN,
 217                 regs->ip)
 218 DO_ERROR(X86_TRAP_OLD_MF, SIGFPE, "coprocessor segment overrun",
 219                 coprocessor_segment_overrun)
 220 DO_ERROR(X86_TRAP_TS, SIGSEGV, "invalid TSS", invalid_TSS)
 221 DO_ERROR(X86_TRAP_NP, SIGBUS, "segment not present", segment_not_present)
 222 #ifdef CONFIG_X86_32
 223 DO_ERROR(X86_TRAP_SS, SIGBUS, "stack segment", stack_segment)
 224 #endif
 225 DO_ERROR_INFO(X86_TRAP_AC, SIGBUS, "alignment check", alignment_check,
 226                 BUS_ADRALN, 0)
 227
 228 #ifdef CONFIG_X86_64
 229 /* Runs on IST stack */
 230 dotraplinkage void do_stack_segment(struct pt_regs *regs, long error_code)
 231 {
 232         exception_enter(regs);
 233         if (notify_die(DIE_TRAP, "stack segment", regs, error_code,
 234                        X86_TRAP_SS, SIGBUS) != NOTIFY_STOP) {
 235                 preempt_conditional_sti(regs);
 236                 do_trap(X86_TRAP_SS, SIGBUS, "stack segment", regs, error_code, NULL);
 237                 preempt_conditional_cli(regs);
 238         }
 239         exception_exit(regs);
 240 }
 241
 242 dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code)
 243 {
 244         static const char str[] = "double fault";
 245         struct task_struct *tsk = current;
 246
 247         exception_enter(regs);
 248         /* Return not checked because double check cannot be ignored */
 249         notify_die(DIE_TRAP, str, regs, error_code, X86_TRAP_DF, SIGSEGV);
 250
 251         tsk->thread.error_code = error_code;
 252         tsk->thread.trap_nr = X86_TRAP_DF;
 253
 254         /*
 255          * This is always a kernel trap and never fixable (and thus must
 256          * never return).
 257          */
 258         for (;;)
 259                 die(str, regs, error_code);
 260 }
 261 #endif
 262
 263 dotraplinkage void __kprobes
 264 do_general_protection(struct pt_regs *regs, long error_code)
 265 {
 266         struct task_struct *tsk;
 267
 268         exception_enter(regs);
 269         conditional_sti(regs);
 270
 271 #ifdef CONFIG_X86_32
 272         if (regs->flags & X86_VM_MASK) {
 273                 local_irq_enable();
 274                 handle_vm86_fault((struct kernel_vm86_regs *) regs, error_code);
 275                 goto exit;
 276         }
 277 #endif
 278
 279         tsk = current;
 280         if (!user_mode(regs)) {
 281                 if (fixup_exception(regs))
 282                         goto exit;
 283
 284                 tsk->thread.error_code = error_code;
 285                 tsk->thread.trap_nr = X86_TRAP_GP;
 286                 if (notify_die(DIE_GPF, "general protection fault", regs, error_code,
 287                                X86_TRAP_GP, SIGSEGV) != NOTIFY_STOP)
 288                         die("general protection fault", regs, error_code);
 289                 goto exit;
 290         }
 291
 292         tsk->thread.error_code = error_code;
 293         tsk->thread.trap_nr = X86_TRAP_GP;
 294
 295         if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) &&
 296                         printk_ratelimit()) {
 297                 pr_info("%s[%d] general protection ip:%lx sp:%lx error:%lx",
 298                         tsk->comm, task_pid_nr(tsk),
 299                         regs->ip, regs->sp, error_code);
 300                 print_vma_addr(" in ", regs->ip);
 301                 pr_cont("\n");
 302         }
 303
 304         force_sig(SIGSEGV, tsk);
 305 exit:
 306         exception_exit(regs);
 307 }
 308
 309 /* May run on IST stack. */
 310 dotraplinkage void __kprobes notrace do_int3(struct pt_regs *regs, long error_code)
 311 {
 312 #ifdef CONFIG_DYNAMIC_FTRACE
 313         /*
 314          * ftrace must be first, everything else may cause a recursive crash.
 315          * See note by declaration of modifying_ftrace_code in ftrace.c
 316          */
 317         if (unlikely(atomic_read(&modifying_ftrace_code)) &&
 318             ftrace_int3_handler(regs))
 319                 return;
 320 #endif
 321         exception_enter(regs);
 322 #ifdef CONFIG_KGDB_LOW_LEVEL_TRAP
 323         if (kgdb_ll_trap(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP,
 324                                 SIGTRAP) == NOTIFY_STOP)
 325                 goto exit;
 326 #endif /* CONFIG_KGDB_LOW_LEVEL_TRAP */
 327
 328         if (notify_die(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP,
 329                         SIGTRAP) == NOTIFY_STOP)
 330                 goto exit;
 331
 332         /*
 333          * Let others (NMI) know that the debug stack is in use
 334          * as we may switch to the interrupt stack.
 335          */
 336         debug_stack_usage_inc();
 337         preempt_conditional_sti(regs);
 338         do_trap(X86_TRAP_BP, SIGTRAP, "int3", regs, error_code, NULL);
 339         preempt_conditional_cli(regs);
 340         debug_stack_usage_dec();
 341 exit:
 342         exception_exit(regs);
 343 }
 344
 345 #ifdef CONFIG_X86_64
 346 /*
 347  * Help handler running on IST stack to switch back to user stack
 348  * for scheduling or signal handling. The actual stack switch is done in
 349  * entry.S
 350  */
 351 asmlinkage __kprobes struct pt_regs *sync_regs(struct pt_regs *eregs)
 352 {
 353         struct pt_regs *regs = eregs;
 354         /* Did already sync */
 355         if (eregs == (struct pt_regs *)eregs->sp)
 356                 ;
 357         /* Exception from user space */
 358         else if (user_mode(eregs))
 359                 regs = task_pt_regs(current);
 360         /*
 361          * Exception from kernel and interrupts are enabled. Move to
 362          * kernel process stack.
 363          */
 364         else if (eregs->flags & X86_EFLAGS_IF)
 365                 regs = (struct pt_regs *)(eregs->sp -= sizeof(struct pt_regs));
 366         if (eregs != regs)
 367                 *regs = *eregs;
 368         return regs;
 369 }
 370 #endif
 371
 372 /*
 373  * Our handling of the processor debug registers is non-trivial.
 374  * We do not clear them on entry and exit from the kernel. Therefore
 375  * it is possible to get a watchpoint trap here from inside the kernel.
 376  * However, the code in ./ptrace.c has ensured that the user can
 377  * only set watchpoints on userspace addresses. Therefore the in-kernel
 378  * watchpoint trap can only occur in code which is reading/writing
 379  * from user space. Such code must not hold kernel locks (since it
 380  * can equally take a page fault), therefore it is safe to call
 381  * force_sig_info even though that claims and releases locks.
 382  *
 383  * Code in ./signal.c ensures that the debug control register
 384  * is restored before we deliver any signal, and therefore that
 385  * user code runs with the correct debug control register even though
 386  * we clear it here.
 387  *
 388  * Being careful here means that we don't have to be as careful in a
 389  * lot of more complicated places (task switching can be a bit lazy
 390  * about restoring all the debug state, and ptrace doesn't have to
 391  * find every occurrence of the TF bit that could be saved away even
 392  * by user code)
 393  *
 394  * May run on IST stack.
 395  */
 396 dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code)
 397 {
 398         struct task_struct *tsk = current;
 399         int user_icebp = 0;
 400         unsigned long dr6;
 401         int si_code;
 402
 403         exception_enter(regs);
 404
 405         get_debugreg(dr6, 6);
 406
 407         /* Filter out all the reserved bits which are preset to 1 */
 408         dr6 &= ~DR6_RESERVED;
 409
 410         /*
 411          * If dr6 has no reason to give us about the origin of this trap,
 412          * then it's very likely the result of an icebp/int01 trap.
 413          * User wants a sigtrap for that.
 414          */
 415         if (!dr6 && user_mode(regs))
 416                 user_icebp = 1;
 417
 418         /* Catch kmemcheck conditions first of all! */
 419         if ((dr6 & DR_STEP) && kmemcheck_trap(regs))
 420                 goto exit;
 421
 422         /* DR6 may or may not be cleared by the CPU */
 423         set_debugreg(0, 6);
 424
 425         /*
 426          * The processor cleared BTF, so don't mark that we need it set.
 427          */
 428         clear_tsk_thread_flag(tsk, TIF_BLOCKSTEP);
 429
 430         /* Store the virtualized DR6 value */
 431         tsk->thread.debugreg6 = dr6;
 432
 433         if (notify_die(DIE_DEBUG, "debug", regs, PTR_ERR(&dr6), error_code,
 434                                                         SIGTRAP) == NOTIFY_STOP)
 435                 goto exit;
 436
 437         /*
 438          * Let others (NMI) know that the debug stack is in use
 439          * as we may switch to the interrupt stack.
 440          */
 441         debug_stack_usage_inc();
 442
 443         /* It's safe to allow irq's after DR6 has been saved */
 444         preempt_conditional_sti(regs);
 445
 446         if (regs->flags & X86_VM_MASK) {
 447                 handle_vm86_trap((struct kernel_vm86_regs *) regs, error_code,
 448                                         X86_TRAP_DB);
 449                 preempt_conditional_cli(regs);
 450                 debug_stack_usage_dec();
 451                 goto exit;
 452         }
 453
 454         /*
 455          * Single-stepping through system calls: ignore any exceptions in
 456          * kernel space, but re-enable TF when returning to user mode.
 457          *
 458          * We already checked v86 mode above, so we can check for kernel mode
 459          * by just checking the CPL of CS.
 460          */
 461         if ((dr6 & DR_STEP) && !user_mode(regs)) {
 462                 tsk->thread.debugreg6 &= ~DR_STEP;
 463                 set_tsk_thread_flag(tsk, TIF_SINGLESTEP);
 464                 regs->flags &= ~X86_EFLAGS_TF;
 465         }
 466         si_code = get_si_code(tsk->thread.debugreg6);
 467         if (tsk->thread.debugreg6 & (DR_STEP | DR_TRAP_BITS) || user_icebp)
 468                 send_sigtrap(tsk, regs, error_code, si_code);
 469         preempt_conditional_cli(regs);
 470         debug_stack_usage_dec();
 471
 472 exit:
 473         exception_exit(regs);
 474 }
 475
 476 /*
 477  * Note that we play around with the 'TS' bit in an attempt to get
 478  * the correct behaviour even in the presence of the asynchronous
 479  * IRQ13 behaviour
 480  */
 481 void math_error(struct pt_regs *regs, int error_code, int trapnr)
 482 {
 483         struct task_struct *task = current;
 484         siginfo_t info;
 485         unsigned short err;
 486         char *str = (trapnr == X86_TRAP_MF) ? "fpu exception" :
 487                                                 "simd exception";
 488
 489         if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, SIGFPE) == NOTIFY_STOP)
 490                 return;
 491         conditional_sti(regs);
 492
 493         if (!user_mode_vm(regs))
 494         {
 495                 if (!fixup_exception(regs)) {
 496                         task->thread.error_code = error_code;
 497                         task->thread.trap_nr = trapnr;
 498                         die(str, regs, error_code);
 499                 }
 500                 return;
 501         }
 502
 503         /*
 504          * Save the info for the exception handler and clear the error.
 505          */
 506         save_init_fpu(task);
 507         task->thread.trap_nr = trapnr;
 508         task->thread.error_code = error_code;
 509         info.si_signo = SIGFPE;
 510         info.si_errno = 0;
 511         info.si_addr = (void __user *)regs->ip;
 512         if (trapnr == X86_TRAP_MF) {
 513                 unsigned short cwd, swd;
 514                 /*
 515                  * (~cwd & swd) will mask out exceptions that are not set to unmasked
 516                  * status.  0x3f is the exception bits in these regs, 0x200 is the
 517                  * C1 reg you need in case of a stack fault, 0x040 is the stack
 518                  * fault bit.  We should only be taking one exception at a time,
 519                  * so if this combination doesn't produce any single exception,
 520                  * then we have a bad program that isn't synchronizing its FPU usage
 521                  * and it will suffer the consequences since we won't be able to
 522                  * fully reproduce the context of the exception
 523                  */
 524                 cwd = get_fpu_cwd(task);
 525                 swd = get_fpu_swd(task);
 526
 527                 err = swd & ~cwd;
 528         } else {
 529                 /*
 530                  * The SIMD FPU exceptions are handled a little differently, as there
 531                  * is only a single status/control register.  Thus, to determine which
 532                  * unmasked exception was caught we must mask the exception mask bits
 533                  * at 0x1f80, and then use these to mask the exception bits at 0x3f.
 534                  */
 535                 unsigned short mxcsr = get_fpu_mxcsr(task);
 536                 err = ~(mxcsr >> 7) & mxcsr;
 537         }
 538
 539         if (err & 0x001) {      /* Invalid op */
 540                 /*
 541                  * swd & 0x240 == 0x040: Stack Underflow
 542                  * swd & 0x240 == 0x240: Stack Overflow
 543                  * User must clear the SF bit (0x40) if set
 544                  */
 545                 info.si_code = FPE_FLTINV;
 546         } else if (err & 0x004) { /* Divide by Zero */
 547                 info.si_code = FPE_FLTDIV;
 548         } else if (err & 0x008) { /* Overflow */
 549                 info.si_code = FPE_FLTOVF;
 550         } else if (err & 0x012) { /* Denormal, Underflow */
 551                 info.si_code = FPE_FLTUND;
 552         } else if (err & 0x020) { /* Precision */
 553                 info.si_code = FPE_FLTRES;
 554         } else {
 555                 /*
 556                  * If we're using IRQ 13, or supposedly even some trap
 557                  * X86_TRAP_MF implementations, it's possible
 558                  * we get a spurious trap, which is not an error.
 559                  */
 560                 return;
 561         }
 562         force_sig_info(SIGFPE, &info, task);
 563 }
 564
 565 dotraplinkage void do_coprocessor_error(struct pt_regs *regs, long error_code)
 566 {
 567 #ifdef CONFIG_X86_32
 568         ignore_fpu_irq = 1;
 569 #endif
 570         exception_enter(regs);
 571         math_error(regs, error_code, X86_TRAP_MF);
 572         exception_exit(regs);
 573 }
 574
 575 dotraplinkage void
 576 do_simd_coprocessor_error(struct pt_regs *regs, long error_code)
 577 {
 578         exception_enter(regs);
 579         math_error(regs, error_code, X86_TRAP_XF);
 580         exception_exit(regs);
 581 }
 582
 583 dotraplinkage void
 584 do_spurious_interrupt_bug(struct pt_regs *regs, long error_code)
 585 {
 586         conditional_sti(regs);
 587 #if 0
 588         /* No need to warn about this any longer. */
 589         pr_info("Ignoring P6 Local APIC Spurious Interrupt Bug...\n");
 590 #endif
 591 }
 592
 593 asmlinkage void __attribute__((weak)) smp_thermal_interrupt(void)
 594 {
 595 }
 596
 597 asmlinkage void __attribute__((weak)) smp_threshold_interrupt(void)
 598 {
 599 }
 600
 601 /*
 602  * 'math_state_restore()' saves the current math information in the
 603  * old math state array, and gets the new ones from the current task
 604  *
 605  * Careful.. There are problems with IBM-designed IRQ13 behaviour.
 606  * Don't touch unless you *really* know how it works.
 607  *
 608  * Must be called with kernel preemption disabled (eg with local
 609  * local interrupts as in the case of do_device_not_available).
 610  */
 611 void math_state_restore(void)
 612 {
 613         struct task_struct *tsk = current;
 614
 615         if (!tsk_used_math(tsk)) {
 616                 local_irq_enable();
 617                 /*
 618                  * does a slab alloc which can sleep
 619                  */
 620                 if (init_fpu(tsk)) {
 621                         /*
 622                          * ran out of memory!
 623                          */
 624                         do_group_exit(SIGKILL);
 625                         return;
 626                 }
 627                 local_irq_disable();
 628         }
 629
 630         __thread_fpu_begin(tsk);
 631
 632         /*
 633          * Paranoid restore. send a SIGSEGV if we fail to restore the state.
 634          */
 635         if (unlikely(restore_fpu_checking(tsk))) {
 636                 drop_init_fpu(tsk);
 637                 force_sig(SIGSEGV, tsk);
 638                 return;
 639         }
 640
 641         tsk->fpu_counter++;
 642 }
 643 EXPORT_SYMBOL_GPL(math_state_restore);
 644
 645 dotraplinkage void __kprobes
 646 do_device_not_available(struct pt_regs *regs, long error_code)
 647 {
 648         exception_enter(regs);
 649         BUG_ON(use_eager_fpu());
 650
 651 #ifdef CONFIG_MATH_EMULATION
 652         if (read_cr0() & X86_CR0_EM) {
 653                 struct math_emu_info info = { };
 654
 655                 conditional_sti(regs);
 656
 657                 info.regs = regs;
 658                 math_emulate(&info);
 659                 exception_exit(regs);
 660                 return;
 661         }
 662 #endif
 663         math_state_restore(); /* interrupts still off */
 664 #ifdef CONFIG_X86_32
 665         conditional_sti(regs);
 666 #endif
 667         exception_exit(regs);
 668 }
 669
 670 #ifdef CONFIG_X86_32
 671 dotraplinkage void do_iret_error(struct pt_regs *regs, long error_code)
 672 {
 673         siginfo_t info;
 674
 675         exception_enter(regs);
 676         local_irq_enable();
 677
 678         info.si_signo = SIGILL;
 679         info.si_errno = 0;
 680         info.si_code = ILL_BADSTK;
 681         info.si_addr = NULL;
 682         if (notify_die(DIE_TRAP, "iret exception", regs, error_code,
 683                         X86_TRAP_IRET, SIGILL) != NOTIFY_STOP) {
 684                 do_trap(X86_TRAP_IRET, SIGILL, "iret exception", regs, error_code,
 685                         &info);
 686         }
 687         exception_exit(regs);
 688 }
 689 #endif
 690
 691 /* Set of traps needed for early debugging. */
 692 void __init early_trap_init(void)
 693 {
 694         set_intr_gate_ist(X86_TRAP_DB, &debug, DEBUG_STACK);
 695         /* int3 can be called from all */
 696         set_system_intr_gate_ist(X86_TRAP_BP, &int3, DEBUG_STACK);
 697         set_intr_gate(X86_TRAP_PF, &page_fault);
 698         load_idt(&idt_descr);
 699 }
 700
 701 void __init trap_init(void)
 702 {
 703         int i;
 704
 705 #ifdef CONFIG_EISA
 706         void __iomem *p = early_ioremap(0x0FFFD9, 4);
 707
 708         if (readl(p) == 'E' + ('I'<<8) + ('S'<<16) + ('A'<<24))
 709                 EISA_bus = 1;
 710         early_iounmap(p, 4);
 711 #endif
 712
 713         set_intr_gate(X86_TRAP_DE, &divide_error);
 714         set_intr_gate_ist(X86_TRAP_NMI, &nmi, NMI_STACK);
 715         /* int4 can be called from all */
 716         set_system_intr_gate(X86_TRAP_OF, &overflow);
 717         set_intr_gate(X86_TRAP_BR, &bounds);
 718         set_intr_gate(X86_TRAP_UD, &invalid_op);
 719         set_intr_gate(X86_TRAP_NM, &device_not_available);
 720 #ifdef CONFIG_X86_32
 721         set_task_gate(X86_TRAP_DF, GDT_ENTRY_DOUBLEFAULT_TSS);
 722 #else
 723         set_intr_gate_ist(X86_TRAP_DF, &double_fault, DOUBLEFAULT_STACK);
 724 #endif
 725         set_intr_gate(X86_TRAP_OLD_MF, &coprocessor_segment_overrun);
 726         set_intr_gate(X86_TRAP_TS, &invalid_TSS);
 727         set_intr_gate(X86_TRAP_NP, &segment_not_present);
 728         set_intr_gate_ist(X86_TRAP_SS, &stack_segment, STACKFAULT_STACK);
 729         set_intr_gate(X86_TRAP_GP, &general_protection);
 730         set_intr_gate(X86_TRAP_SPURIOUS, &spurious_interrupt_bug);
 731         set_intr_gate(X86_TRAP_MF, &coprocessor_error);
 732         set_intr_gate(X86_TRAP_AC, &alignment_check);
 733 #ifdef CONFIG_X86_MCE
 734         set_intr_gate_ist(X86_TRAP_MC, &machine_check, MCE_STACK);
 735 #endif
 736         set_intr_gate(X86_TRAP_XF, &simd_coprocessor_error);
 737
 738         /* Reserve all the builtin and the syscall vector: */
 739         for (i = 0; i < FIRST_EXTERNAL_VECTOR; i++)
 740                 set_bit(i, used_vectors);
 741
 742 #ifdef CONFIG_IA32_EMULATION
 743         set_system_intr_gate(IA32_SYSCALL_VECTOR, ia32_syscall);
 744         set_bit(IA32_SYSCALL_VECTOR, used_vectors);
 745 #endif
 746
 747 #ifdef CONFIG_X86_32
 748         set_system_trap_gate(SYSCALL_VECTOR, &system_call);
 749         set_bit(SYSCALL_VECTOR, used_vectors);
 750 #endif
 751
 752         /*
 753          * Should be a barrier for any external CPU state:
 754          */
 755         cpu_init();
 756
 757         x86_init.irqs.trap_init();
 758
 759 #ifdef CONFIG_X86_64
 760         memcpy(&nmi_idt_table, &idt_table, IDT_ENTRIES * 16);
 761         set_nmi_gate(X86_TRAP_DB, &debug);
 762         set_nmi_gate(X86_TRAP_BP, &int3);
 763 #endif
 764 }