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, regs->ip )
 215 DO_ERROR     (X86_TRAP_OF,     SIGSEGV, "overflow",                     overflow                                          )
 216 DO_ERROR     (X86_TRAP_BR,     SIGSEGV, "bounds",                       bounds                                            )
 217 DO_ERROR_INFO(X86_TRAP_UD,     SIGILL,  "invalid opcode",               invalid_op,                  ILL_ILLOPN, regs->ip )
 218 DO_ERROR     (X86_TRAP_OLD_MF, SIGFPE,  "coprocessor segment overrun",  coprocessor_segment_overrun                       )
 219 DO_ERROR     (X86_TRAP_TS,     SIGSEGV, "invalid TSS",                  invalid_TSS                                       )
 220 DO_ERROR     (X86_TRAP_NP,     SIGBUS,  "segment not present",          segment_not_present                               )
 221 #ifdef CONFIG_X86_32
 222 DO_ERROR     (X86_TRAP_SS,     SIGBUS,  "stack segment",                stack_segment                                     )
 223 #endif
 224 DO_ERROR_INFO(X86_TRAP_AC,     SIGBUS,  "alignment check",              alignment_check,             BUS_ADRALN, 0        )
 225
 226 #ifdef CONFIG_X86_64
 227 /* Runs on IST stack */
 228 dotraplinkage void do_stack_segment(struct pt_regs *regs, long error_code)
 229 {
 230         enum ctx_state prev_state;
 231
 232         prev_state = exception_enter();
 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(prev_state);
 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();
 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 #ifdef CONFIG_DOUBLEFAULT
 255         df_debug(regs, error_code);
 256 #endif
 257         /*
 258          * This is always a kernel trap and never fixable (and thus must
 259          * never return).
 260          */
 261         for (;;)
 262                 die(str, regs, error_code);
 263 }
 264 #endif
 265
 266 dotraplinkage void __kprobes
 267 do_general_protection(struct pt_regs *regs, long error_code)
 268 {
 269         struct task_struct *tsk;
 270         enum ctx_state prev_state;
 271
 272         prev_state = exception_enter();
 273         conditional_sti(regs);
 274
 275 #ifdef CONFIG_X86_32
 276         if (regs->flags & X86_VM_MASK) {
 277                 local_irq_enable();
 278                 handle_vm86_fault((struct kernel_vm86_regs *) regs, error_code);
 279                 goto exit;
 280         }
 281 #endif
 282
 283         tsk = current;
 284         if (!user_mode(regs)) {
 285                 if (fixup_exception(regs))
 286                         goto exit;
 287
 288                 tsk->thread.error_code = error_code;
 289                 tsk->thread.trap_nr = X86_TRAP_GP;
 290                 if (notify_die(DIE_GPF, "general protection fault", regs, error_code,
 291                                X86_TRAP_GP, SIGSEGV) != NOTIFY_STOP)
 292                         die("general protection fault", regs, error_code);
 293                 goto exit;
 294         }
 295
 296         tsk->thread.error_code = error_code;
 297         tsk->thread.trap_nr = X86_TRAP_GP;
 298
 299         if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) &&
 300                         printk_ratelimit()) {
 301                 pr_info("%s[%d] general protection ip:%lx sp:%lx error:%lx",
 302                         tsk->comm, task_pid_nr(tsk),
 303                         regs->ip, regs->sp, error_code);
 304                 print_vma_addr(" in ", regs->ip);
 305                 pr_cont("\n");
 306         }
 307
 308         force_sig(SIGSEGV, tsk);
 309 exit:
 310         exception_exit(prev_state);
 311 }
 312
 313 /* May run on IST stack. */
 314 dotraplinkage void __kprobes notrace do_int3(struct pt_regs *regs, long error_code)
 315 {
 316         enum ctx_state prev_state;
 317
 318 #ifdef CONFIG_DYNAMIC_FTRACE
 319         /*
 320          * ftrace must be first, everything else may cause a recursive crash.
 321          * See note by declaration of modifying_ftrace_code in ftrace.c
 322          */
 323         if (unlikely(atomic_read(&modifying_ftrace_code)) &&
 324             ftrace_int3_handler(regs))
 325                 return;
 326 #endif
 327         if (poke_int3_handler(regs))
 328                 return;
 329
 330         prev_state = exception_enter();
 331 #ifdef CONFIG_KGDB_LOW_LEVEL_TRAP
 332         if (kgdb_ll_trap(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP,
 333                                 SIGTRAP) == NOTIFY_STOP)
 334                 goto exit;
 335 #endif /* CONFIG_KGDB_LOW_LEVEL_TRAP */
 336
 337         if (notify_die(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP,
 338                         SIGTRAP) == NOTIFY_STOP)
 339                 goto exit;
 340
 341         /*
 342          * Let others (NMI) know that the debug stack is in use
 343          * as we may switch to the interrupt stack.
 344          */
 345         debug_stack_usage_inc();
 346         preempt_conditional_sti(regs);
 347         do_trap(X86_TRAP_BP, SIGTRAP, "int3", regs, error_code, NULL);
 348         preempt_conditional_cli(regs);
 349         debug_stack_usage_dec();
 350 exit:
 351         exception_exit(prev_state);
 352 }
 353
 354 #ifdef CONFIG_X86_64
 355 /*
 356  * Help handler running on IST stack to switch back to user stack
 357  * for scheduling or signal handling. The actual stack switch is done in
 358  * entry.S
 359  */
 360 asmlinkage __kprobes struct pt_regs *sync_regs(struct pt_regs *eregs)
 361 {
 362         struct pt_regs *regs = eregs;
 363         /* Did already sync */
 364         if (eregs == (struct pt_regs *)eregs->sp)
 365                 ;
 366         /* Exception from user space */
 367         else if (user_mode(eregs))
 368                 regs = task_pt_regs(current);
 369         /*
 370          * Exception from kernel and interrupts are enabled. Move to
 371          * kernel process stack.
 372          */
 373         else if (eregs->flags & X86_EFLAGS_IF)
 374                 regs = (struct pt_regs *)(eregs->sp -= sizeof(struct pt_regs));
 375         if (eregs != regs)
 376                 *regs = *eregs;
 377         return regs;
 378 }
 379 #endif
 380
 381 /*
 382  * Our handling of the processor debug registers is non-trivial.
 383  * We do not clear them on entry and exit from the kernel. Therefore
 384  * it is possible to get a watchpoint trap here from inside the kernel.
 385  * However, the code in ./ptrace.c has ensured that the user can
 386  * only set watchpoints on userspace addresses. Therefore the in-kernel
 387  * watchpoint trap can only occur in code which is reading/writing
 388  * from user space. Such code must not hold kernel locks (since it
 389  * can equally take a page fault), therefore it is safe to call
 390  * force_sig_info even though that claims and releases locks.
 391  *
 392  * Code in ./signal.c ensures that the debug control register
 393  * is restored before we deliver any signal, and therefore that
 394  * user code runs with the correct debug control register even though
 395  * we clear it here.
 396  *
 397  * Being careful here means that we don't have to be as careful in a
 398  * lot of more complicated places (task switching can be a bit lazy
 399  * about restoring all the debug state, and ptrace doesn't have to
 400  * find every occurrence of the TF bit that could be saved away even
 401  * by user code)
 402  *
 403  * May run on IST stack.
 404  */
 405 dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code)
 406 {
 407         struct task_struct *tsk = current;
 408         enum ctx_state prev_state;
 409         int user_icebp = 0;
 410         unsigned long dr6;
 411         int si_code;
 412
 413         prev_state = exception_enter();
 414
 415         get_debugreg(dr6, 6);
 416
 417         /* Filter out all the reserved bits which are preset to 1 */
 418         dr6 &= ~DR6_RESERVED;
 419
 420         /*
 421          * If dr6 has no reason to give us about the origin of this trap,
 422          * then it's very likely the result of an icebp/int01 trap.
 423          * User wants a sigtrap for that.
 424          */
 425         if (!dr6 && user_mode(regs))
 426                 user_icebp = 1;
 427
 428         /* Catch kmemcheck conditions first of all! */
 429         if ((dr6 & DR_STEP) && kmemcheck_trap(regs))
 430                 goto exit;
 431
 432         /* DR6 may or may not be cleared by the CPU */
 433         set_debugreg(0, 6);
 434
 435         /*
 436          * The processor cleared BTF, so don't mark that we need it set.
 437          */
 438         clear_tsk_thread_flag(tsk, TIF_BLOCKSTEP);
 439
 440         /* Store the virtualized DR6 value */
 441         tsk->thread.debugreg6 = dr6;
 442
 443         if (notify_die(DIE_DEBUG, "debug", regs, (long)&dr6, error_code,
 444                                                         SIGTRAP) == NOTIFY_STOP)
 445                 goto exit;
 446
 447         /*
 448          * Let others (NMI) know that the debug stack is in use
 449          * as we may switch to the interrupt stack.
 450          */
 451         debug_stack_usage_inc();
 452
 453         /* It's safe to allow irq's after DR6 has been saved */
 454         preempt_conditional_sti(regs);
 455
 456         if (regs->flags & X86_VM_MASK) {
 457                 handle_vm86_trap((struct kernel_vm86_regs *) regs, error_code,
 458                                         X86_TRAP_DB);
 459                 preempt_conditional_cli(regs);
 460                 debug_stack_usage_dec();
 461                 goto exit;
 462         }
 463
 464         /*
 465          * Single-stepping through system calls: ignore any exceptions in
 466          * kernel space, but re-enable TF when returning to user mode.
 467          *
 468          * We already checked v86 mode above, so we can check for kernel mode
 469          * by just checking the CPL of CS.
 470          */
 471         if ((dr6 & DR_STEP) && !user_mode(regs)) {
 472                 tsk->thread.debugreg6 &= ~DR_STEP;
 473                 set_tsk_thread_flag(tsk, TIF_SINGLESTEP);
 474                 regs->flags &= ~X86_EFLAGS_TF;
 475         }
 476         si_code = get_si_code(tsk->thread.debugreg6);
 477         if (tsk->thread.debugreg6 & (DR_STEP | DR_TRAP_BITS) || user_icebp)
 478                 send_sigtrap(tsk, regs, error_code, si_code);
 479         preempt_conditional_cli(regs);
 480         debug_stack_usage_dec();
 481
 482 exit:
 483         exception_exit(prev_state);
 484 }
 485
 486 /*
 487  * Note that we play around with the 'TS' bit in an attempt to get
 488  * the correct behaviour even in the presence of the asynchronous
 489  * IRQ13 behaviour
 490  */
 491 void math_error(struct pt_regs *regs, int error_code, int trapnr)
 492 {
 493         struct task_struct *task = current;
 494         siginfo_t info;
 495         unsigned short err;
 496         char *str = (trapnr == X86_TRAP_MF) ? "fpu exception" :
 497                                                 "simd exception";
 498
 499         if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, SIGFPE) == NOTIFY_STOP)
 500                 return;
 501         conditional_sti(regs);
 502
 503         if (!user_mode_vm(regs))
 504         {
 505                 if (!fixup_exception(regs)) {
 506                         task->thread.error_code = error_code;
 507                         task->thread.trap_nr = trapnr;
 508                         die(str, regs, error_code);
 509                 }
 510                 return;
 511         }
 512
 513         /*
 514          * Save the info for the exception handler and clear the error.
 515          */
 516         save_init_fpu(task);
 517         task->thread.trap_nr = trapnr;
 518         task->thread.error_code = error_code;
 519         info.si_signo = SIGFPE;
 520         info.si_errno = 0;
 521         info.si_addr = (void __user *)regs->ip;
 522         if (trapnr == X86_TRAP_MF) {
 523                 unsigned short cwd, swd;
 524                 /*
 525                  * (~cwd & swd) will mask out exceptions that are not set to unmasked
 526                  * status.  0x3f is the exception bits in these regs, 0x200 is the
 527                  * C1 reg you need in case of a stack fault, 0x040 is the stack
 528                  * fault bit.  We should only be taking one exception at a time,
 529                  * so if this combination doesn't produce any single exception,
 530                  * then we have a bad program that isn't synchronizing its FPU usage
 531                  * and it will suffer the consequences since we won't be able to
 532                  * fully reproduce the context of the exception
 533                  */
 534                 cwd = get_fpu_cwd(task);
 535                 swd = get_fpu_swd(task);
 536
 537                 err = swd & ~cwd;
 538         } else {
 539                 /*
 540                  * The SIMD FPU exceptions are handled a little differently, as there
 541                  * is only a single status/control register.  Thus, to determine which
 542                  * unmasked exception was caught we must mask the exception mask bits
 543                  * at 0x1f80, and then use these to mask the exception bits at 0x3f.
 544                  */
 545                 unsigned short mxcsr = get_fpu_mxcsr(task);
 546                 err = ~(mxcsr >> 7) & mxcsr;
 547         }
 548
 549         if (err & 0x001) {      /* Invalid op */
 550                 /*
 551                  * swd & 0x240 == 0x040: Stack Underflow
 552                  * swd & 0x240 == 0x240: Stack Overflow
 553                  * User must clear the SF bit (0x40) if set
 554                  */
 555                 info.si_code = FPE_FLTINV;
 556         } else if (err & 0x004) { /* Divide by Zero */
 557                 info.si_code = FPE_FLTDIV;
 558         } else if (err & 0x008) { /* Overflow */
 559                 info.si_code = FPE_FLTOVF;
 560         } else if (err & 0x012) { /* Denormal, Underflow */
 561                 info.si_code = FPE_FLTUND;
 562         } else if (err & 0x020) { /* Precision */
 563                 info.si_code = FPE_FLTRES;
 564         } else {
 565                 /*
 566                  * If we're using IRQ 13, or supposedly even some trap
 567                  * X86_TRAP_MF implementations, it's possible
 568                  * we get a spurious trap, which is not an error.
 569                  */
 570                 return;
 571         }
 572         force_sig_info(SIGFPE, &info, task);
 573 }
 574
 575 dotraplinkage void do_coprocessor_error(struct pt_regs *regs, long error_code)
 576 {
 577         enum ctx_state prev_state;
 578
 579         prev_state = exception_enter();
 580         math_error(regs, error_code, X86_TRAP_MF);
 581         exception_exit(prev_state);
 582 }
 583
 584 dotraplinkage void
 585 do_simd_coprocessor_error(struct pt_regs *regs, long error_code)
 586 {
 587         enum ctx_state prev_state;
 588
 589         prev_state = exception_enter();
 590         math_error(regs, error_code, X86_TRAP_XF);
 591         exception_exit(prev_state);
 592 }
 593
 594 dotraplinkage void
 595 do_spurious_interrupt_bug(struct pt_regs *regs, long error_code)
 596 {
 597         conditional_sti(regs);
 598 #if 0
 599         /* No need to warn about this any longer. */
 600         pr_info("Ignoring P6 Local APIC Spurious Interrupt Bug...\n");
 601 #endif
 602 }
 603
 604 asmlinkage void __attribute__((weak)) smp_thermal_interrupt(void)
 605 {
 606 }
 607
 608 asmlinkage void __attribute__((weak)) smp_threshold_interrupt(void)
 609 {
 610 }
 611
 612 /*
 613  * 'math_state_restore()' saves the current math information in the
 614  * old math state array, and gets the new ones from the current task
 615  *
 616  * Careful.. There are problems with IBM-designed IRQ13 behaviour.
 617  * Don't touch unless you *really* know how it works.
 618  *
 619  * Must be called with kernel preemption disabled (eg with local
 620  * local interrupts as in the case of do_device_not_available).
 621  */
 622 void math_state_restore(void)
 623 {
 624         struct task_struct *tsk = current;
 625
 626         if (!tsk_used_math(tsk)) {
 627                 local_irq_enable();
 628                 /*
 629                  * does a slab alloc which can sleep
 630                  */
 631                 if (init_fpu(tsk)) {
 632                         /*
 633                          * ran out of memory!
 634                          */
 635                         do_group_exit(SIGKILL);
 636                         return;
 637                 }
 638                 local_irq_disable();
 639         }
 640
 641         __thread_fpu_begin(tsk);
 642
 643         /*
 644          * Paranoid restore. send a SIGSEGV if we fail to restore the state.
 645          */
 646         if (unlikely(restore_fpu_checking(tsk))) {
 647                 drop_init_fpu(tsk);
 648                 force_sig(SIGSEGV, tsk);
 649                 return;
 650         }
 651
 652         tsk->thread.fpu_counter++;
 653 }
 654 EXPORT_SYMBOL_GPL(math_state_restore);
 655
 656 dotraplinkage void __kprobes
 657 do_device_not_available(struct pt_regs *regs, long error_code)
 658 {
 659         enum ctx_state prev_state;
 660
 661         prev_state = exception_enter();
 662         BUG_ON(use_eager_fpu());
 663
 664 #ifdef CONFIG_MATH_EMULATION
 665         if (read_cr0() & X86_CR0_EM) {
 666                 struct math_emu_info info = { };
 667
 668                 conditional_sti(regs);
 669
 670                 info.regs = regs;
 671                 math_emulate(&info);
 672                 exception_exit(prev_state);
 673                 return;
 674         }
 675 #endif
 676         math_state_restore(); /* interrupts still off */
 677 #ifdef CONFIG_X86_32
 678         conditional_sti(regs);
 679 #endif
 680         exception_exit(prev_state);
 681 }
 682
 683 #ifdef CONFIG_X86_32
 684 dotraplinkage void do_iret_error(struct pt_regs *regs, long error_code)
 685 {
 686         siginfo_t info;
 687         enum ctx_state prev_state;
 688
 689         prev_state = exception_enter();
 690         local_irq_enable();
 691
 692         info.si_signo = SIGILL;
 693         info.si_errno = 0;
 694         info.si_code = ILL_BADSTK;
 695         info.si_addr = NULL;
 696         if (notify_die(DIE_TRAP, "iret exception", regs, error_code,
 697                         X86_TRAP_IRET, SIGILL) != NOTIFY_STOP) {
 698                 do_trap(X86_TRAP_IRET, SIGILL, "iret exception", regs, error_code,
 699                         &info);
 700         }
 701         exception_exit(prev_state);
 702 }
 703 #endif
 704
 705 /* Set of traps needed for early debugging. */
 706 void __init early_trap_init(void)
 707 {
 708         set_intr_gate_ist(X86_TRAP_DB, &debug, DEBUG_STACK);
 709         /* int3 can be called from all */
 710         set_system_intr_gate_ist(X86_TRAP_BP, &int3, DEBUG_STACK);
 711 #ifdef CONFIG_X86_32
 712         set_intr_gate(X86_TRAP_PF, page_fault);
 713 #endif
 714         load_idt(&idt_descr);
 715 }
 716
 717 void __init early_trap_pf_init(void)
 718 {
 719 #ifdef CONFIG_X86_64
 720         set_intr_gate(X86_TRAP_PF, page_fault);
 721 #endif
 722 }
 723
 724 void __init trap_init(void)
 725 {
 726         int i;
 727
 728 #ifdef CONFIG_EISA
 729         void __iomem *p = early_ioremap(0x0FFFD9, 4);
 730
 731         if (readl(p) == 'E' + ('I'<<8) + ('S'<<16) + ('A'<<24))
 732                 EISA_bus = 1;
 733         early_iounmap(p, 4);
 734 #endif
 735
 736         set_intr_gate(X86_TRAP_DE, divide_error);
 737         set_intr_gate_ist(X86_TRAP_NMI, &nmi, NMI_STACK);
 738         /* int4 can be called from all */
 739         set_system_intr_gate(X86_TRAP_OF, &overflow);
 740         set_intr_gate(X86_TRAP_BR, bounds);
 741         set_intr_gate(X86_TRAP_UD, invalid_op);
 742         set_intr_gate(X86_TRAP_NM, device_not_available);
 743 #ifdef CONFIG_X86_32
 744         set_task_gate(X86_TRAP_DF, GDT_ENTRY_DOUBLEFAULT_TSS);
 745 #else
 746         set_intr_gate_ist(X86_TRAP_DF, &double_fault, DOUBLEFAULT_STACK);
 747 #endif
 748         set_intr_gate(X86_TRAP_OLD_MF, coprocessor_segment_overrun);
 749         set_intr_gate(X86_TRAP_TS, invalid_TSS);
 750         set_intr_gate(X86_TRAP_NP, segment_not_present);
 751         set_intr_gate_ist(X86_TRAP_SS, &stack_segment, STACKFAULT_STACK);
 752         set_intr_gate(X86_TRAP_GP, general_protection);
 753         set_intr_gate(X86_TRAP_SPURIOUS, spurious_interrupt_bug);
 754         set_intr_gate(X86_TRAP_MF, coprocessor_error);
 755         set_intr_gate(X86_TRAP_AC, alignment_check);
 756 #ifdef CONFIG_X86_MCE
 757         set_intr_gate_ist(X86_TRAP_MC, &machine_check, MCE_STACK);
 758 #endif
 759         set_intr_gate(X86_TRAP_XF, simd_coprocessor_error);
 760
 761         /* Reserve all the builtin and the syscall vector: */
 762         for (i = 0; i < FIRST_EXTERNAL_VECTOR; i++)
 763                 set_bit(i, used_vectors);
 764
 765 #ifdef CONFIG_IA32_EMULATION
 766         set_system_intr_gate(IA32_SYSCALL_VECTOR, ia32_syscall);
 767         set_bit(IA32_SYSCALL_VECTOR, used_vectors);
 768 #endif
 769
 770 #ifdef CONFIG_X86_32
 771         set_system_trap_gate(SYSCALL_VECTOR, &system_call);
 772         set_bit(SYSCALL_VECTOR, used_vectors);
 773 #endif
 774
 775         /*
 776          * Set the IDT descriptor to a fixed read-only location, so that the
 777          * "sidt" instruction will not leak the location of the kernel, and
 778          * to defend the IDT against arbitrary memory write vulnerabilities.
 779          * It will be reloaded in cpu_init() */
 780         __set_fixmap(FIX_RO_IDT, __pa_symbol(idt_table), PAGE_KERNEL_RO);
 781         idt_descr.address = fix_to_virt(FIX_RO_IDT);
 782
 783         /*
 784          * Should be a barrier for any external CPU state:
 785          */
 786         cpu_init();
 787
 788         x86_init.irqs.trap_init();
 789
 790 #ifdef CONFIG_X86_64
 791         memcpy(&debug_idt_table, &idt_table, IDT_ENTRIES * 16);
 792         set_nmi_gate(X86_TRAP_DB, &debug);
 793         set_nmi_gate(X86_TRAP_BP, &int3);
 794 #endif
 795 }