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/context_tracking.h>
  16 #include <linux/interrupt.h>
  17 #include <linux/kallsyms.h>
  18 #include <linux/spinlock.h>
  19 #include <linux/kprobes.h>
  20 #include <linux/uaccess.h>
  21 #include <linux/kdebug.h>
  22 #include <linux/kgdb.h>
  23 #include <linux/kernel.h>
  24 #include <linux/module.h>
  25 #include <linux/ptrace.h>
  26 #include <linux/string.h>
  27 #include <linux/delay.h>
  28 #include <linux/errno.h>
  29 #include <linux/kexec.h>
  30 #include <linux/sched.h>
  31 #include <linux/timer.h>
  32 #include <linux/init.h>
  33 #include <linux/bug.h>
  34 #include <linux/nmi.h>
  35 #include <linux/mm.h>
  36 #include <linux/smp.h>
  37 #include <linux/io.h>
  38
  39 #ifdef CONFIG_EISA
  40 #include <linux/ioport.h>
  41 #include <linux/eisa.h>
  42 #endif
  43
  44 #if defined(CONFIG_EDAC)
  45 #include <linux/edac.h>
  46 #endif
  47
  48 #include <asm/kmemcheck.h>
  49 #include <asm/stacktrace.h>
  50 #include <asm/processor.h>
  51 #include <asm/debugreg.h>
  52 #include <linux/atomic.h>
  53 #include <asm/ftrace.h>
  54 #include <asm/traps.h>
  55 #include <asm/desc.h>
  56 #include <asm/i387.h>
  57 #include <asm/fpu-internal.h>
  58 #include <asm/mce.h>
  59 #include <asm/fixmap.h>
  60 #include <asm/mach_traps.h>
  61 #include <asm/alternative.h>
  62
  63 #ifdef CONFIG_X86_64
  64 #include <asm/x86_init.h>
  65 #include <asm/pgalloc.h>
  66 #include <asm/proto.h>
  67
  68 /* No need to be aligned, but done to keep all IDTs defined the same way. */
  69 gate_desc debug_idt_table[NR_VECTORS] __page_aligned_bss;
  70 #else
  71 #include <asm/processor-flags.h>
  72 #include <asm/setup.h>
  73
  74 asmlinkage int system_call(void);
  75 #endif
  76
  77 /* Must be page-aligned because the real IDT is used in a fixmap. */
  78 gate_desc idt_table[NR_VECTORS] __page_aligned_bss;
  79
  80 DECLARE_BITMAP(used_vectors, NR_VECTORS);
  81 EXPORT_SYMBOL_GPL(used_vectors);
  82
  83 static inline void conditional_sti(struct pt_regs *regs)
  84 {
  85         if (regs->flags & X86_EFLAGS_IF)
  86                 local_irq_enable();
  87 }
  88
  89 static inline void preempt_conditional_sti(struct pt_regs *regs)
  90 {
  91         preempt_count_inc();
  92         if (regs->flags & X86_EFLAGS_IF)
  93                 local_irq_enable();
  94 }
  95
  96 static inline void conditional_cli(struct pt_regs *regs)
  97 {
  98         if (regs->flags & X86_EFLAGS_IF)
  99                 local_irq_disable();
 100 }
 101
 102 static inline void preempt_conditional_cli(struct pt_regs *regs)
 103 {
 104         if (regs->flags & X86_EFLAGS_IF)
 105                 local_irq_disable();
 106         preempt_count_dec();
 107 }
 108
 109 static int __kprobes
 110 do_trap_no_signal(struct task_struct *tsk, int trapnr, char *str,
 111                   struct pt_regs *regs, long error_code)
 112 {
 113 #ifdef CONFIG_X86_32
 114         if (regs->flags & X86_VM_MASK) {
 115                 /*
 116                  * Traps 0, 1, 3, 4, and 5 should be forwarded to vm86.
 117                  * On nmi (interrupt 2), do_trap should not be called.
 118                  */
 119                 if (trapnr < X86_TRAP_UD) {
 120                         if (!handle_vm86_trap((struct kernel_vm86_regs *) regs,
 121                                                 error_code, trapnr))
 122                                 return 0;
 123                 }
 124                 return -1;
 125         }
 126 #endif
 127         if (!user_mode(regs)) {
 128                 if (!fixup_exception(regs)) {
 129                         tsk->thread.error_code = error_code;
 130                         tsk->thread.trap_nr = trapnr;
 131                         die(str, regs, error_code);
 132                 }
 133                 return 0;
 134         }
 135
 136         return -1;
 137 }
 138
 139 static void __kprobes
 140 do_trap(int trapnr, int signr, char *str, struct pt_regs *regs,
 141         long error_code, siginfo_t *info)
 142 {
 143         struct task_struct *tsk = current;
 144
 145
 146         if (!do_trap_no_signal(tsk, trapnr, str, regs, error_code))
 147                 return;
 148         /*
 149          * We want error_code and trap_nr set for userspace faults and
 150          * kernelspace faults which result in die(), but not
 151          * kernelspace faults which are fixed up.  die() gives the
 152          * process no chance to handle the signal and notice the
 153          * kernel fault information, so that won't result in polluting
 154          * the information about previously queued, but not yet
 155          * delivered, faults.  See also do_general_protection below.
 156          */
 157         tsk->thread.error_code = error_code;
 158         tsk->thread.trap_nr = trapnr;
 159
 160 #ifdef CONFIG_X86_64
 161         if (show_unhandled_signals && unhandled_signal(tsk, signr) &&
 162             printk_ratelimit()) {
 163                 pr_info("%s[%d] trap %s ip:%lx sp:%lx error:%lx",
 164                         tsk->comm, tsk->pid, str,
 165                         regs->ip, regs->sp, error_code);
 166                 print_vma_addr(" in ", regs->ip);
 167                 pr_cont("\n");
 168         }
 169 #endif
 170
 171         if (info)
 172                 force_sig_info(signr, info, tsk);
 173         else
 174                 force_sig(signr, tsk);
 175 }
 176
 177 #define DO_ERROR(trapnr, signr, str, name)                              \
 178 dotraplinkage void do_##name(struct pt_regs *regs, long error_code)     \
 179 {                                                                       \
 180         enum ctx_state prev_state;                                      \
 181                                                                         \
 182         prev_state = exception_enter();                                 \
 183         if (notify_die(DIE_TRAP, str, regs, error_code,                 \
 184                         trapnr, signr) == NOTIFY_STOP) {                \
 185                 exception_exit(prev_state);                             \
 186                 return;                                                 \
 187         }                                                               \
 188         conditional_sti(regs);                                          \
 189         do_trap(trapnr, signr, str, regs, error_code, NULL);            \
 190         exception_exit(prev_state);                                     \
 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         enum ctx_state prev_state;                                      \
 198                                                                         \
 199         info.si_signo = signr;                                          \
 200         info.si_errno = 0;                                              \
 201         info.si_code = sicode;                                          \
 202         info.si_addr = (void __user *)siaddr;                           \
 203         prev_state = exception_enter();                                 \
 204         if (notify_die(DIE_TRAP, str, regs, error_code,                 \
 205                         trapnr, signr) == NOTIFY_STOP) {                \
 206                 exception_exit(prev_state);                             \
 207                 return;                                                 \
 208         }                                                               \
 209         conditional_sti(regs);                                          \
 210         do_trap(trapnr, signr, str, regs, error_code, &info);           \
 211         exception_exit(prev_state);                                     \
 212 }
 213
 214 DO_ERROR_INFO(X86_TRAP_DE, SIGFPE, "divide error", divide_error, FPE_INTDIV,
 215                 regs->ip)
 216 DO_ERROR(X86_TRAP_OF, SIGSEGV, "overflow", overflow)
 217 DO_ERROR(X86_TRAP_BR, SIGSEGV, "bounds", bounds)
 218 DO_ERROR_INFO(X86_TRAP_UD, SIGILL, "invalid opcode", invalid_op, ILL_ILLOPN,
 219                 regs->ip)
 220 DO_ERROR(X86_TRAP_OLD_MF, SIGFPE, "coprocessor segment overrun",
 221                 coprocessor_segment_overrun)
 222 DO_ERROR(X86_TRAP_TS, SIGSEGV, "invalid TSS", invalid_TSS)
 223 DO_ERROR(X86_TRAP_NP, SIGBUS, "segment not present", segment_not_present)
 224 #ifdef CONFIG_X86_32
 225 DO_ERROR(X86_TRAP_SS, SIGBUS, "stack segment", stack_segment)
 226 #endif
 227 DO_ERROR_INFO(X86_TRAP_AC, SIGBUS, "alignment check", alignment_check,
 228                 BUS_ADRALN, 0)
 229
 230 #ifdef CONFIG_X86_64
 231 /* Runs on IST stack */
 232 dotraplinkage void do_stack_segment(struct pt_regs *regs, long error_code)
 233 {
 234         enum ctx_state prev_state;
 235
 236         prev_state = exception_enter();
 237         if (notify_die(DIE_TRAP, "stack segment", regs, error_code,
 238                        X86_TRAP_SS, SIGBUS) != NOTIFY_STOP) {
 239                 preempt_conditional_sti(regs);
 240                 do_trap(X86_TRAP_SS, SIGBUS, "stack segment", regs, error_code, NULL);
 241                 preempt_conditional_cli(regs);
 242         }
 243         exception_exit(prev_state);
 244 }
 245
 246 dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code)
 247 {
 248         static const char str[] = "double fault";
 249         struct task_struct *tsk = current;
 250
 251         exception_enter();
 252         /* Return not checked because double check cannot be ignored */
 253         notify_die(DIE_TRAP, str, regs, error_code, X86_TRAP_DF, SIGSEGV);
 254
 255         tsk->thread.error_code = error_code;
 256         tsk->thread.trap_nr = X86_TRAP_DF;
 257
 258 #ifdef CONFIG_DOUBLEFAULT
 259         df_debug(regs, error_code);
 260 #endif
 261         /*
 262          * This is always a kernel trap and never fixable (and thus must
 263          * never return).
 264          */
 265         for (;;)
 266                 die(str, regs, error_code);
 267 }
 268 #endif
 269
 270 dotraplinkage void __kprobes
 271 do_general_protection(struct pt_regs *regs, long error_code)
 272 {
 273         struct task_struct *tsk;
 274         enum ctx_state prev_state;
 275
 276         prev_state = exception_enter();
 277         conditional_sti(regs);
 278
 279 #ifdef CONFIG_X86_32
 280         if (regs->flags & X86_VM_MASK) {
 281                 local_irq_enable();
 282                 handle_vm86_fault((struct kernel_vm86_regs *) regs, error_code);
 283                 goto exit;
 284         }
 285 #endif
 286
 287         tsk = current;
 288         if (!user_mode(regs)) {
 289                 if (fixup_exception(regs))
 290                         goto exit;
 291
 292                 tsk->thread.error_code = error_code;
 293                 tsk->thread.trap_nr = X86_TRAP_GP;
 294                 if (notify_die(DIE_GPF, "general protection fault", regs, error_code,
 295                                X86_TRAP_GP, SIGSEGV) != NOTIFY_STOP)
 296                         die("general protection fault", regs, error_code);
 297                 goto exit;
 298         }
 299
 300         tsk->thread.error_code = error_code;
 301         tsk->thread.trap_nr = X86_TRAP_GP;
 302
 303         if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) &&
 304                         printk_ratelimit()) {
 305                 pr_info("%s[%d] general protection ip:%lx sp:%lx error:%lx",
 306                         tsk->comm, task_pid_nr(tsk),
 307                         regs->ip, regs->sp, error_code);
 308                 print_vma_addr(" in ", regs->ip);
 309                 pr_cont("\n");
 310         }
 311
 312         force_sig(SIGSEGV, tsk);
 313 exit:
 314         exception_exit(prev_state);
 315 }
 316
 317 /* May run on IST stack. */
 318 dotraplinkage void __kprobes notrace do_int3(struct pt_regs *regs, long error_code)
 319 {
 320         enum ctx_state prev_state;
 321
 322 #ifdef CONFIG_DYNAMIC_FTRACE
 323         /*
 324          * ftrace must be first, everything else may cause a recursive crash.
 325          * See note by declaration of modifying_ftrace_code in ftrace.c
 326          */
 327         if (unlikely(atomic_read(&modifying_ftrace_code)) &&
 328             ftrace_int3_handler(regs))
 329                 return;
 330 #endif
 331         if (poke_int3_handler(regs))
 332                 return;
 333
 334         prev_state = exception_enter();
 335 #ifdef CONFIG_KGDB_LOW_LEVEL_TRAP
 336         if (kgdb_ll_trap(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP,
 337                                 SIGTRAP) == NOTIFY_STOP)
 338                 goto exit;
 339 #endif /* CONFIG_KGDB_LOW_LEVEL_TRAP */
 340
 341         if (notify_die(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP,
 342                         SIGTRAP) == NOTIFY_STOP)
 343                 goto exit;
 344
 345         /*
 346          * Let others (NMI) know that the debug stack is in use
 347          * as we may switch to the interrupt stack.
 348          */
 349         debug_stack_usage_inc();
 350         preempt_conditional_sti(regs);
 351         do_trap(X86_TRAP_BP, SIGTRAP, "int3", regs, error_code, NULL);
 352         preempt_conditional_cli(regs);
 353         debug_stack_usage_dec();
 354 exit:
 355         exception_exit(prev_state);
 356 }
 357
 358 #ifdef CONFIG_X86_64
 359 /*
 360  * Help handler running on IST stack to switch back to user stack
 361  * for scheduling or signal handling. The actual stack switch is done in
 362  * entry.S
 363  */
 364 asmlinkage __kprobes struct pt_regs *sync_regs(struct pt_regs *eregs)
 365 {
 366         struct pt_regs *regs = eregs;
 367         /* Did already sync */
 368         if (eregs == (struct pt_regs *)eregs->sp)
 369                 ;
 370         /* Exception from user space */
 371         else if (user_mode(eregs))
 372                 regs = task_pt_regs(current);
 373         /*
 374          * Exception from kernel and interrupts are enabled. Move to
 375          * kernel process stack.
 376          */
 377         else if (eregs->flags & X86_EFLAGS_IF)
 378                 regs = (struct pt_regs *)(eregs->sp -= sizeof(struct pt_regs));
 379         if (eregs != regs)
 380                 *regs = *eregs;
 381         return regs;
 382 }
 383 #endif
 384
 385 /*
 386  * Our handling of the processor debug registers is non-trivial.
 387  * We do not clear them on entry and exit from the kernel. Therefore
 388  * it is possible to get a watchpoint trap here from inside the kernel.
 389  * However, the code in ./ptrace.c has ensured that the user can
 390  * only set watchpoints on userspace addresses. Therefore the in-kernel
 391  * watchpoint trap can only occur in code which is reading/writing
 392  * from user space. Such code must not hold kernel locks (since it
 393  * can equally take a page fault), therefore it is safe to call
 394  * force_sig_info even though that claims and releases locks.
 395  *
 396  * Code in ./signal.c ensures that the debug control register
 397  * is restored before we deliver any signal, and therefore that
 398  * user code runs with the correct debug control register even though
 399  * we clear it here.
 400  *
 401  * Being careful here means that we don't have to be as careful in a
 402  * lot of more complicated places (task switching can be a bit lazy
 403  * about restoring all the debug state, and ptrace doesn't have to
 404  * find every occurrence of the TF bit that could be saved away even
 405  * by user code)
 406  *
 407  * May run on IST stack.
 408  */
 409 dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code)
 410 {
 411         struct task_struct *tsk = current;
 412         enum ctx_state prev_state;
 413         int user_icebp = 0;
 414         unsigned long dr6;
 415         int si_code;
 416
 417         prev_state = exception_enter();
 418
 419         get_debugreg(dr6, 6);
 420
 421         /* Filter out all the reserved bits which are preset to 1 */
 422         dr6 &= ~DR6_RESERVED;
 423
 424         /*
 425          * If dr6 has no reason to give us about the origin of this trap,
 426          * then it's very likely the result of an icebp/int01 trap.
 427          * User wants a sigtrap for that.
 428          */
 429         if (!dr6 && user_mode(regs))
 430                 user_icebp = 1;
 431
 432         /* Catch kmemcheck conditions first of all! */
 433         if ((dr6 & DR_STEP) && kmemcheck_trap(regs))
 434                 goto exit;
 435
 436         /* DR6 may or may not be cleared by the CPU */
 437         set_debugreg(0, 6);
 438
 439         /*
 440          * The processor cleared BTF, so don't mark that we need it set.
 441          */
 442         clear_tsk_thread_flag(tsk, TIF_BLOCKSTEP);
 443
 444         /* Store the virtualized DR6 value */
 445         tsk->thread.debugreg6 = dr6;
 446
 447         if (notify_die(DIE_DEBUG, "debug", regs, (long)&dr6, error_code,
 448                                                         SIGTRAP) == NOTIFY_STOP)
 449                 goto exit;
 450
 451         /*
 452          * Let others (NMI) know that the debug stack is in use
 453          * as we may switch to the interrupt stack.
 454          */
 455         debug_stack_usage_inc();
 456
 457         /* It's safe to allow irq's after DR6 has been saved */
 458         preempt_conditional_sti(regs);
 459
 460         if (regs->flags & X86_VM_MASK) {
 461                 handle_vm86_trap((struct kernel_vm86_regs *) regs, error_code,
 462                                         X86_TRAP_DB);
 463                 preempt_conditional_cli(regs);
 464                 debug_stack_usage_dec();
 465                 goto exit;
 466         }
 467
 468         /*
 469          * Single-stepping through system calls: ignore any exceptions in
 470          * kernel space, but re-enable TF when returning to user mode.
 471          *
 472          * We already checked v86 mode above, so we can check for kernel mode
 473          * by just checking the CPL of CS.
 474          */
 475         if ((dr6 & DR_STEP) && !user_mode(regs)) {
 476                 tsk->thread.debugreg6 &= ~DR_STEP;
 477                 set_tsk_thread_flag(tsk, TIF_SINGLESTEP);
 478                 regs->flags &= ~X86_EFLAGS_TF;
 479         }
 480         si_code = get_si_code(tsk->thread.debugreg6);
 481         if (tsk->thread.debugreg6 & (DR_STEP | DR_TRAP_BITS) || user_icebp)
 482                 send_sigtrap(tsk, regs, error_code, si_code);
 483         preempt_conditional_cli(regs);
 484         debug_stack_usage_dec();
 485
 486 exit:
 487         exception_exit(prev_state);
 488 }
 489
 490 /*
 491  * Note that we play around with the 'TS' bit in an attempt to get
 492  * the correct behaviour even in the presence of the asynchronous
 493  * IRQ13 behaviour
 494  */
 495 void math_error(struct pt_regs *regs, int error_code, int trapnr)
 496 {
 497         struct task_struct *task = current;
 498         siginfo_t info;
 499         unsigned short err;
 500         char *str = (trapnr == X86_TRAP_MF) ? "fpu exception" :
 501                                                 "simd exception";
 502
 503         if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, SIGFPE) == NOTIFY_STOP)
 504                 return;
 505         conditional_sti(regs);
 506
 507         if (!user_mode_vm(regs))
 508         {
 509                 if (!fixup_exception(regs)) {
 510                         task->thread.error_code = error_code;
 511                         task->thread.trap_nr = trapnr;
 512                         die(str, regs, error_code);
 513                 }
 514                 return;
 515         }
 516
 517         /*
 518          * Save the info for the exception handler and clear the error.
 519          */
 520         save_init_fpu(task);
 521         task->thread.trap_nr = trapnr;
 522         task->thread.error_code = error_code;
 523         info.si_signo = SIGFPE;
 524         info.si_errno = 0;
 525         info.si_addr = (void __user *)regs->ip;
 526         if (trapnr == X86_TRAP_MF) {
 527                 unsigned short cwd, swd;
 528                 /*
 529                  * (~cwd & swd) will mask out exceptions that are not set to unmasked
 530                  * status.  0x3f is the exception bits in these regs, 0x200 is the
 531                  * C1 reg you need in case of a stack fault, 0x040 is the stack
 532                  * fault bit.  We should only be taking one exception at a time,
 533                  * so if this combination doesn't produce any single exception,
 534                  * then we have a bad program that isn't synchronizing its FPU usage
 535                  * and it will suffer the consequences since we won't be able to
 536                  * fully reproduce the context of the exception
 537                  */
 538                 cwd = get_fpu_cwd(task);
 539                 swd = get_fpu_swd(task);
 540
 541                 err = swd & ~cwd;
 542         } else {
 543                 /*
 544                  * The SIMD FPU exceptions are handled a little differently, as there
 545                  * is only a single status/control register.  Thus, to determine which
 546                  * unmasked exception was caught we must mask the exception mask bits
 547                  * at 0x1f80, and then use these to mask the exception bits at 0x3f.
 548                  */
 549                 unsigned short mxcsr = get_fpu_mxcsr(task);
 550                 err = ~(mxcsr >> 7) & mxcsr;
 551         }
 552
 553         if (err & 0x001) {      /* Invalid op */
 554                 /*
 555                  * swd & 0x240 == 0x040: Stack Underflow
 556                  * swd & 0x240 == 0x240: Stack Overflow
 557                  * User must clear the SF bit (0x40) if set
 558                  */
 559                 info.si_code = FPE_FLTINV;
 560         } else if (err & 0x004) { /* Divide by Zero */
 561                 info.si_code = FPE_FLTDIV;
 562         } else if (err & 0x008) { /* Overflow */
 563                 info.si_code = FPE_FLTOVF;
 564         } else if (err & 0x012) { /* Denormal, Underflow */
 565                 info.si_code = FPE_FLTUND;
 566         } else if (err & 0x020) { /* Precision */
 567                 info.si_code = FPE_FLTRES;
 568         } else {
 569                 /*
 570                  * If we're using IRQ 13, or supposedly even some trap
 571                  * X86_TRAP_MF implementations, it's possible
 572                  * we get a spurious trap, which is not an error.
 573                  */
 574                 return;
 575         }
 576         force_sig_info(SIGFPE, &info, task);
 577 }
 578
 579 dotraplinkage void do_coprocessor_error(struct pt_regs *regs, long error_code)
 580 {
 581         enum ctx_state prev_state;
 582
 583         prev_state = exception_enter();
 584         math_error(regs, error_code, X86_TRAP_MF);
 585         exception_exit(prev_state);
 586 }
 587
 588 dotraplinkage void
 589 do_simd_coprocessor_error(struct pt_regs *regs, long error_code)
 590 {
 591         enum ctx_state prev_state;
 592
 593         prev_state = exception_enter();
 594         math_error(regs, error_code, X86_TRAP_XF);
 595         exception_exit(prev_state);
 596 }
 597
 598 dotraplinkage void
 599 do_spurious_interrupt_bug(struct pt_regs *regs, long error_code)
 600 {
 601         conditional_sti(regs);
 602 #if 0
 603         /* No need to warn about this any longer. */
 604         pr_info("Ignoring P6 Local APIC Spurious Interrupt Bug...\n");
 605 #endif
 606 }
 607
 608 asmlinkage void __attribute__((weak)) smp_thermal_interrupt(void)
 609 {
 610 }
 611
 612 asmlinkage void __attribute__((weak)) smp_threshold_interrupt(void)
 613 {
 614 }
 615
 616 /*
 617  * 'math_state_restore()' saves the current math information in the
 618  * old math state array, and gets the new ones from the current task
 619  *
 620  * Careful.. There are problems with IBM-designed IRQ13 behaviour.
 621  * Don't touch unless you *really* know how it works.
 622  *
 623  * Must be called with kernel preemption disabled (eg with local
 624  * local interrupts as in the case of do_device_not_available).
 625  */
 626 void math_state_restore(void)
 627 {
 628         struct task_struct *tsk = current;
 629
 630         if (!tsk_used_math(tsk)) {
 631                 local_irq_enable();
 632                 /*
 633                  * does a slab alloc which can sleep
 634                  */
 635                 if (init_fpu(tsk)) {
 636                         /*
 637                          * ran out of memory!
 638                          */
 639                         do_group_exit(SIGKILL);
 640                         return;
 641                 }
 642                 local_irq_disable();
 643         }
 644
 645         __thread_fpu_begin(tsk);
 646
 647         /*
 648          * Paranoid restore. send a SIGSEGV if we fail to restore the state.
 649          */
 650         if (unlikely(restore_fpu_checking(tsk))) {
 651                 drop_init_fpu(tsk);
 652                 force_sig(SIGSEGV, tsk);
 653                 return;
 654         }
 655
 656         tsk->thread.fpu_counter++;
 657 }
 658 EXPORT_SYMBOL_GPL(math_state_restore);
 659
 660 dotraplinkage void __kprobes
 661 do_device_not_available(struct pt_regs *regs, long error_code)
 662 {
 663         enum ctx_state prev_state;
 664
 665         prev_state = exception_enter();
 666         BUG_ON(use_eager_fpu());
 667
 668 #ifdef CONFIG_MATH_EMULATION
 669         if (read_cr0() & X86_CR0_EM) {
 670                 struct math_emu_info info = { };
 671
 672                 conditional_sti(regs);
 673
 674                 info.regs = regs;
 675                 math_emulate(&info);
 676                 exception_exit(prev_state);
 677                 return;
 678         }
 679 #endif
 680         math_state_restore(); /* interrupts still off */
 681 #ifdef CONFIG_X86_32
 682         conditional_sti(regs);
 683 #endif
 684         exception_exit(prev_state);
 685 }
 686
 687 #ifdef CONFIG_X86_32
 688 dotraplinkage void do_iret_error(struct pt_regs *regs, long error_code)
 689 {
 690         siginfo_t info;
 691         enum ctx_state prev_state;
 692
 693         prev_state = exception_enter();
 694         local_irq_enable();
 695
 696         info.si_signo = SIGILL;
 697         info.si_errno = 0;
 698         info.si_code = ILL_BADSTK;
 699         info.si_addr = NULL;
 700         if (notify_die(DIE_TRAP, "iret exception", regs, error_code,
 701                         X86_TRAP_IRET, SIGILL) != NOTIFY_STOP) {
 702                 do_trap(X86_TRAP_IRET, SIGILL, "iret exception", regs, error_code,
 703                         &info);
 704         }
 705         exception_exit(prev_state);
 706 }
 707 #endif
 708
 709 /* Set of traps needed for early debugging. */
 710 void __init early_trap_init(void)
 711 {
 712         set_intr_gate_ist(X86_TRAP_DB, &debug, DEBUG_STACK);
 713         /* int3 can be called from all */
 714         set_system_intr_gate_ist(X86_TRAP_BP, &int3, DEBUG_STACK);
 715 #ifdef CONFIG_X86_32
 716         set_intr_gate(X86_TRAP_PF, page_fault);
 717 #endif
 718         load_idt(&idt_descr);
 719 }
 720
 721 void __init early_trap_pf_init(void)
 722 {
 723 #ifdef CONFIG_X86_64
 724         set_intr_gate(X86_TRAP_PF, page_fault);
 725 #endif
 726 }
 727
 728 void __init trap_init(void)
 729 {
 730         int i;
 731
 732 #ifdef CONFIG_EISA
 733         void __iomem *p = early_ioremap(0x0FFFD9, 4);
 734
 735         if (readl(p) == 'E' + ('I'<<8) + ('S'<<16) + ('A'<<24))
 736                 EISA_bus = 1;
 737         early_iounmap(p, 4);
 738 #endif
 739
 740         set_intr_gate(X86_TRAP_DE, divide_error);
 741         set_intr_gate_ist(X86_TRAP_NMI, &nmi, NMI_STACK);
 742         /* int4 can be called from all */
 743         set_system_intr_gate(X86_TRAP_OF, &overflow);
 744         set_intr_gate(X86_TRAP_BR, bounds);
 745         set_intr_gate(X86_TRAP_UD, invalid_op);
 746         set_intr_gate(X86_TRAP_NM, device_not_available);
 747 #ifdef CONFIG_X86_32
 748         set_task_gate(X86_TRAP_DF, GDT_ENTRY_DOUBLEFAULT_TSS);
 749 #else
 750         set_intr_gate_ist(X86_TRAP_DF, &double_fault, DOUBLEFAULT_STACK);
 751 #endif
 752         set_intr_gate(X86_TRAP_OLD_MF, coprocessor_segment_overrun);
 753         set_intr_gate(X86_TRAP_TS, invalid_TSS);
 754         set_intr_gate(X86_TRAP_NP, segment_not_present);
 755         set_intr_gate_ist(X86_TRAP_SS, &stack_segment, STACKFAULT_STACK);
 756         set_intr_gate(X86_TRAP_GP, general_protection);
 757         set_intr_gate(X86_TRAP_SPURIOUS, spurious_interrupt_bug);
 758         set_intr_gate(X86_TRAP_MF, coprocessor_error);
 759         set_intr_gate(X86_TRAP_AC, alignment_check);
 760 #ifdef CONFIG_X86_MCE
 761         set_intr_gate_ist(X86_TRAP_MC, &machine_check, MCE_STACK);
 762 #endif
 763         set_intr_gate(X86_TRAP_XF, simd_coprocessor_error);
 764
 765         /* Reserve all the builtin and the syscall vector: */
 766         for (i = 0; i < FIRST_EXTERNAL_VECTOR; i++)
 767                 set_bit(i, used_vectors);
 768
 769 #ifdef CONFIG_IA32_EMULATION
 770         set_system_intr_gate(IA32_SYSCALL_VECTOR, ia32_syscall);
 771         set_bit(IA32_SYSCALL_VECTOR, used_vectors);
 772 #endif
 773
 774 #ifdef CONFIG_X86_32
 775         set_system_trap_gate(SYSCALL_VECTOR, &system_call);
 776         set_bit(SYSCALL_VECTOR, used_vectors);
 777 #endif
 778
 779         /*
 780          * Set the IDT descriptor to a fixed read-only location, so that the
 781          * "sidt" instruction will not leak the location of the kernel, and
 782          * to defend the IDT against arbitrary memory write vulnerabilities.
 783          * It will be reloaded in cpu_init() */
 784         __set_fixmap(FIX_RO_IDT, __pa_symbol(idt_table), PAGE_KERNEL_RO);
 785         idt_descr.address = fix_to_virt(FIX_RO_IDT);
 786
 787         /*
 788          * Should be a barrier for any external CPU state:
 789          */
 790         cpu_init();
 791
 792         x86_init.irqs.trap_init();
 793
 794 #ifdef CONFIG_X86_64
 795         memcpy(&debug_idt_table, &idt_table, IDT_ENTRIES * 16);
 796         set_nmi_gate(X86_TRAP_DB, &debug);
 797         set_nmi_gate(X86_TRAP_BP, &int3);
 798 #endif
 799 }