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