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 #include <linux/interrupt.h>
  13 #include <linux/kallsyms.h>
  14 #include <linux/spinlock.h>
  15 #include <linux/kprobes.h>
  16 #include <linux/uaccess.h>
  17 #include <linux/kdebug.h>
  18 #include <linux/kgdb.h>
  19 #include <linux/kernel.h>
  20 #include <linux/module.h>
  21 #include <linux/ptrace.h>
  22 #include <linux/string.h>
  23 #include <linux/delay.h>
  24 #include <linux/errno.h>
  25 #include <linux/kexec.h>
  26 #include <linux/sched.h>
  27 #include <linux/timer.h>
  28 #include <linux/init.h>
  29 #include <linux/bug.h>
  30 #include <linux/nmi.h>
  31 #include <linux/mm.h>
  32 #include <linux/smp.h>
  33 #include <linux/io.h>
  34
  35 #ifdef CONFIG_EISA
  36 #include <linux/ioport.h>
  37 #include <linux/eisa.h>
  38 #endif
  39
  40 #ifdef CONFIG_MCA
  41 #include <linux/mca.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 <asm/atomic.h>
  53 #include <asm/system.h>
  54 #include <asm/traps.h>
  55 #include <asm/desc.h>
  56 #include <asm/i387.h>
  57 #include <asm/mce.h>
  58
  59 #include <asm/mach_traps.h>
  60
  61 #ifdef CONFIG_X86_64
  62 #include <asm/x86_init.h>
  63 #include <asm/pgalloc.h>
  64 #include <asm/proto.h>
  65 #else
  66 #include <asm/processor-flags.h>
  67 #include <asm/setup.h>
  68
  69 asmlinkage int system_call(void);
  70
  71 /* Do we ignore FPU interrupts ? */
  72 char ignore_fpu_irq;
  73
  74 /*
  75  * The IDT has to be page-aligned to simplify the Pentium
  76  * F0 0F bug workaround.
  77  */
  78 gate_desc idt_table[NR_VECTORS] __page_aligned_data = { { { { 0, 0 } } }, };
  79 #endif
  80
  81 DECLARE_BITMAP(used_vectors, NR_VECTORS);
  82 EXPORT_SYMBOL_GPL(used_vectors);
  83
  84 static int ignore_nmis;
  85
  86 static inline void conditional_sti(struct pt_regs *regs)
  87 {
  88         if (regs->flags & X86_EFLAGS_IF)
  89                 local_irq_enable();
  90 }
  91
  92 static inline void preempt_conditional_sti(struct pt_regs *regs)
  93 {
  94         inc_preempt_count();
  95         if (regs->flags & X86_EFLAGS_IF)
  96                 local_irq_enable();
  97 }
  98
  99 static inline void conditional_cli(struct pt_regs *regs)
 100 {
 101         if (regs->flags & X86_EFLAGS_IF)
 102                 local_irq_disable();
 103 }
 104
 105 static inline void preempt_conditional_cli(struct pt_regs *regs)
 106 {
 107         if (regs->flags & X86_EFLAGS_IF)
 108                 local_irq_disable();
 109         dec_preempt_count();
 110 }
 111
 112 static void __kprobes
 113 do_trap(int trapnr, int signr, char *str, struct pt_regs *regs,
 114         long error_code, siginfo_t *info)
 115 {
 116         struct task_struct *tsk = current;
 117
 118 #ifdef CONFIG_X86_32
 119         if (regs->flags & X86_VM_MASK) {
 120                 /*
 121                  * traps 0, 1, 3, 4, and 5 should be forwarded to vm86.
 122                  * On nmi (interrupt 2), do_trap should not be called.
 123                  */
 124                 if (trapnr < 6)
 125                         goto vm86_trap;
 126                 goto trap_signal;
 127         }
 128 #endif
 129
 130         if (!user_mode(regs))
 131                 goto kernel_trap;
 132
 133 #ifdef CONFIG_X86_32
 134 trap_signal:
 135 #endif
 136         /*
 137          * We want error_code and trap_no set for userspace faults and
 138          * kernelspace faults which result in die(), but not
 139          * kernelspace faults which are fixed up.  die() gives the
 140          * process no chance to handle the signal and notice the
 141          * kernel fault information, so that won't result in polluting
 142          * the information about previously queued, but not yet
 143          * delivered, faults.  See also do_general_protection below.
 144          */
 145         tsk->thread.error_code = error_code;
 146         tsk->thread.trap_no = trapnr;
 147
 148 #ifdef CONFIG_X86_64
 149         if (show_unhandled_signals && unhandled_signal(tsk, signr) &&
 150             printk_ratelimit()) {
 151                 printk(KERN_INFO
 152                        "%s[%d] trap %s ip:%lx sp:%lx error:%lx",
 153                        tsk->comm, tsk->pid, str,
 154                        regs->ip, regs->sp, error_code);
 155                 print_vma_addr(" in ", regs->ip);
 156                 printk("\n");
 157         }
 158 #endif
 159
 160         if (info)
 161                 force_sig_info(signr, info, tsk);
 162         else
 163                 force_sig(signr, tsk);
 164         return;
 165
 166 kernel_trap:
 167         if (!fixup_exception(regs)) {
 168                 tsk->thread.error_code = error_code;
 169                 tsk->thread.trap_no = trapnr;
 170                 die(str, regs, error_code);
 171         }
 172         return;
 173
 174 #ifdef CONFIG_X86_32
 175 vm86_trap:
 176         if (handle_vm86_trap((struct kernel_vm86_regs *) regs,
 177                                                 error_code, trapnr))
 178                 goto trap_signal;
 179         return;
 180 #endif
 181 }
 182
 183 #define DO_ERROR(trapnr, signr, str, name)                              \
 184 dotraplinkage void do_##name(struct pt_regs *regs, long error_code)     \
 185 {                                                                       \
 186         if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr)  \
 187                                                         == NOTIFY_STOP) \
 188                 return;                                                 \
 189         conditional_sti(regs);                                          \
 190         do_trap(trapnr, signr, str, regs, error_code, NULL);            \
 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         if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr)  \
 202                                                         == NOTIFY_STOP) \
 203                 return;                                                 \
 204         conditional_sti(regs);                                          \
 205         do_trap(trapnr, signr, str, regs, error_code, &info);           \
 206 }
 207
 208 DO_ERROR_INFO(0, SIGFPE, "divide error", divide_error, FPE_INTDIV, regs->ip)
 209 DO_ERROR(4, SIGSEGV, "overflow", overflow)
 210 DO_ERROR(5, SIGSEGV, "bounds", bounds)
 211 DO_ERROR_INFO(6, SIGILL, "invalid opcode", invalid_op, ILL_ILLOPN, regs->ip)
 212 DO_ERROR(9, SIGFPE, "coprocessor segment overrun", coprocessor_segment_overrun)
 213 DO_ERROR(10, SIGSEGV, "invalid TSS", invalid_TSS)
 214 DO_ERROR(11, SIGBUS, "segment not present", segment_not_present)
 215 #ifdef CONFIG_X86_32
 216 DO_ERROR(12, SIGBUS, "stack segment", stack_segment)
 217 #endif
 218 DO_ERROR_INFO(17, SIGBUS, "alignment check", alignment_check, BUS_ADRALN, 0)
 219
 220 #ifdef CONFIG_X86_64
 221 /* Runs on IST stack */
 222 dotraplinkage void do_stack_segment(struct pt_regs *regs, long error_code)
 223 {
 224         if (notify_die(DIE_TRAP, "stack segment", regs, error_code,
 225                         12, SIGBUS) == NOTIFY_STOP)
 226                 return;
 227         preempt_conditional_sti(regs);
 228         do_trap(12, SIGBUS, "stack segment", regs, error_code, NULL);
 229         preempt_conditional_cli(regs);
 230 }
 231
 232 dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code)
 233 {
 234         static const char str[] = "double fault";
 235         struct task_struct *tsk = current;
 236
 237         /* Return not checked because double check cannot be ignored */
 238         notify_die(DIE_TRAP, str, regs, error_code, 8, SIGSEGV);
 239
 240         tsk->thread.error_code = error_code;
 241         tsk->thread.trap_no = 8;
 242
 243         /*
 244          * This is always a kernel trap and never fixable (and thus must
 245          * never return).
 246          */
 247         for (;;)
 248                 die(str, regs, error_code);
 249 }
 250 #endif
 251
 252 dotraplinkage void __kprobes
 253 do_general_protection(struct pt_regs *regs, long error_code)
 254 {
 255         struct task_struct *tsk;
 256
 257         conditional_sti(regs);
 258
 259 #ifdef CONFIG_X86_32
 260         if (regs->flags & X86_VM_MASK)
 261                 goto gp_in_vm86;
 262 #endif
 263
 264         tsk = current;
 265         if (!user_mode(regs))
 266                 goto gp_in_kernel;
 267
 268         tsk->thread.error_code = error_code;
 269         tsk->thread.trap_no = 13;
 270
 271         if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) &&
 272                         printk_ratelimit()) {
 273                 printk(KERN_INFO
 274                         "%s[%d] general protection ip:%lx sp:%lx error:%lx",
 275                         tsk->comm, task_pid_nr(tsk),
 276                         regs->ip, regs->sp, error_code);
 277                 print_vma_addr(" in ", regs->ip);
 278                 printk("\n");
 279         }
 280
 281         force_sig(SIGSEGV, tsk);
 282         return;
 283
 284 #ifdef CONFIG_X86_32
 285 gp_in_vm86:
 286         local_irq_enable();
 287         handle_vm86_fault((struct kernel_vm86_regs *) regs, error_code);
 288         return;
 289 #endif
 290
 291 gp_in_kernel:
 292         if (fixup_exception(regs))
 293                 return;
 294
 295         tsk->thread.error_code = error_code;
 296         tsk->thread.trap_no = 13;
 297         if (notify_die(DIE_GPF, "general protection fault", regs,
 298                                 error_code, 13, SIGSEGV) == NOTIFY_STOP)
 299                 return;
 300         die("general protection fault", regs, error_code);
 301 }
 302
 303 static notrace __kprobes void
 304 mem_parity_error(unsigned char reason, struct pt_regs *regs)
 305 {
 306         printk(KERN_EMERG
 307                 "Uhhuh. NMI received for unknown reason %02x on CPU %d.\n",
 308                         reason, smp_processor_id());
 309
 310         printk(KERN_EMERG
 311                 "You have some hardware problem, likely on the PCI bus.\n");
 312
 313 #if defined(CONFIG_EDAC)
 314         if (edac_handler_set()) {
 315                 edac_atomic_assert_error();
 316                 return;
 317         }
 318 #endif
 319
 320         if (panic_on_unrecovered_nmi)
 321                 panic("NMI: Not continuing");
 322
 323         printk(KERN_EMERG "Dazed and confused, but trying to continue\n");
 324
 325         /* Clear and disable the memory parity error line. */
 326         reason = (reason & 0xf) | 4;
 327         outb(reason, 0x61);
 328 }
 329
 330 static notrace __kprobes void
 331 io_check_error(unsigned char reason, struct pt_regs *regs)
 332 {
 333         unsigned long i;
 334
 335         printk(KERN_EMERG "NMI: IOCK error (debug interrupt?)\n");
 336         show_registers(regs);
 337
 338         if (panic_on_io_nmi)
 339                 panic("NMI IOCK error: Not continuing");
 340
 341         /* Re-enable the IOCK line, wait for a few seconds */
 342         reason = (reason & 0xf) | 8;
 343         outb(reason, 0x61);
 344
 345         i = 2000;
 346         while (--i)
 347                 udelay(1000);
 348
 349         reason &= ~8;
 350         outb(reason, 0x61);
 351 }
 352
 353 static notrace __kprobes void
 354 unknown_nmi_error(unsigned char reason, struct pt_regs *regs)
 355 {
 356         if (notify_die(DIE_NMIUNKNOWN, "nmi", regs, reason, 2, SIGINT) ==
 357                         NOTIFY_STOP)
 358                 return;
 359 #ifdef CONFIG_MCA
 360         /*
 361          * Might actually be able to figure out what the guilty party
 362          * is:
 363          */
 364         if (MCA_bus) {
 365                 mca_handle_nmi();
 366                 return;
 367         }
 368 #endif
 369         printk(KERN_EMERG
 370                 "Uhhuh. NMI received for unknown reason %02x on CPU %d.\n",
 371                         reason, smp_processor_id());
 372
 373         printk(KERN_EMERG "Do you have a strange power saving mode enabled?\n");
 374         if (panic_on_unrecovered_nmi)
 375                 panic("NMI: Not continuing");
 376
 377         printk(KERN_EMERG "Dazed and confused, but trying to continue\n");
 378 }
 379
 380 static notrace __kprobes void default_do_nmi(struct pt_regs *regs)
 381 {
 382         unsigned char reason = 0;
 383         int cpu;
 384
 385         cpu = smp_processor_id();
 386
 387         /* Only the BSP gets external NMIs from the system. */
 388         if (!cpu)
 389                 reason = get_nmi_reason();
 390
 391         if (!(reason & 0xc0)) {
 392                 if (notify_die(DIE_NMI_IPI, "nmi_ipi", regs, reason, 2, SIGINT)
 393                                                                 == NOTIFY_STOP)
 394                         return;
 395
 396 #ifdef CONFIG_X86_LOCAL_APIC
 397                 if (notify_die(DIE_NMI, "nmi", regs, reason, 2, SIGINT)
 398                                                         == NOTIFY_STOP)
 399                         return;
 400
 401 #ifndef CONFIG_LOCKUP_DETECTOR
 402                 /*
 403                  * Ok, so this is none of the documented NMI sources,
 404                  * so it must be the NMI watchdog.
 405                  */
 406                 if (nmi_watchdog_tick(regs, reason))
 407                         return;
 408                 if (!do_nmi_callback(regs, cpu))
 409 #endif /* !CONFIG_LOCKUP_DETECTOR */
 410                         unknown_nmi_error(reason, regs);
 411 #else
 412                 unknown_nmi_error(reason, regs);
 413 #endif
 414
 415                 return;
 416         }
 417         if (notify_die(DIE_NMI, "nmi", regs, reason, 2, SIGINT) == NOTIFY_STOP)
 418                 return;
 419
 420         /* AK: following checks seem to be broken on modern chipsets. FIXME */
 421         if (reason & 0x80)
 422                 mem_parity_error(reason, regs);
 423         if (reason & 0x40)
 424                 io_check_error(reason, regs);
 425 #ifdef CONFIG_X86_32
 426         /*
 427          * Reassert NMI in case it became active meanwhile
 428          * as it's edge-triggered:
 429          */
 430         reassert_nmi();
 431 #endif
 432 }
 433
 434 dotraplinkage notrace __kprobes void
 435 do_nmi(struct pt_regs *regs, long error_code)
 436 {
 437         nmi_enter();
 438
 439         inc_irq_stat(__nmi_count);
 440
 441         if (!ignore_nmis)
 442                 default_do_nmi(regs);
 443
 444         nmi_exit();
 445 }
 446
 447 void stop_nmi(void)
 448 {
 449         acpi_nmi_disable();
 450         ignore_nmis++;
 451 }
 452
 453 void restart_nmi(void)
 454 {
 455         ignore_nmis--;
 456         acpi_nmi_enable();
 457 }
 458
 459 /* May run on IST stack. */
 460 dotraplinkage void __kprobes do_int3(struct pt_regs *regs, long error_code)
 461 {
 462 #ifdef CONFIG_KGDB_LOW_LEVEL_TRAP
 463         if (kgdb_ll_trap(DIE_INT3, "int3", regs, error_code, 3, SIGTRAP)
 464                         == NOTIFY_STOP)
 465                 return;
 466 #endif /* CONFIG_KGDB_LOW_LEVEL_TRAP */
 467 #ifdef CONFIG_KPROBES
 468         if (notify_die(DIE_INT3, "int3", regs, error_code, 3, SIGTRAP)
 469                         == NOTIFY_STOP)
 470                 return;
 471 #else
 472         if (notify_die(DIE_TRAP, "int3", regs, error_code, 3, SIGTRAP)
 473                         == NOTIFY_STOP)
 474                 return;
 475 #endif
 476
 477         preempt_conditional_sti(regs);
 478         do_trap(3, SIGTRAP, "int3", regs, error_code, NULL);
 479         preempt_conditional_cli(regs);
 480 }
 481
 482 #ifdef CONFIG_X86_64
 483 /*
 484  * Help handler running on IST stack to switch back to user stack
 485  * for scheduling or signal handling. The actual stack switch is done in
 486  * entry.S
 487  */
 488 asmlinkage __kprobes struct pt_regs *sync_regs(struct pt_regs *eregs)
 489 {
 490         struct pt_regs *regs = eregs;
 491         /* Did already sync */
 492         if (eregs == (struct pt_regs *)eregs->sp)
 493                 ;
 494         /* Exception from user space */
 495         else if (user_mode(eregs))
 496                 regs = task_pt_regs(current);
 497         /*
 498          * Exception from kernel and interrupts are enabled. Move to
 499          * kernel process stack.
 500          */
 501         else if (eregs->flags & X86_EFLAGS_IF)
 502                 regs = (struct pt_regs *)(eregs->sp -= sizeof(struct pt_regs));
 503         if (eregs != regs)
 504                 *regs = *eregs;
 505         return regs;
 506 }
 507 #endif
 508
 509 /*
 510  * Our handling of the processor debug registers is non-trivial.
 511  * We do not clear them on entry and exit from the kernel. Therefore
 512  * it is possible to get a watchpoint trap here from inside the kernel.
 513  * However, the code in ./ptrace.c has ensured that the user can
 514  * only set watchpoints on userspace addresses. Therefore the in-kernel
 515  * watchpoint trap can only occur in code which is reading/writing
 516  * from user space. Such code must not hold kernel locks (since it
 517  * can equally take a page fault), therefore it is safe to call
 518  * force_sig_info even though that claims and releases locks.
 519  *
 520  * Code in ./signal.c ensures that the debug control register
 521  * is restored before we deliver any signal, and therefore that
 522  * user code runs with the correct debug control register even though
 523  * we clear it here.
 524  *
 525  * Being careful here means that we don't have to be as careful in a
 526  * lot of more complicated places (task switching can be a bit lazy
 527  * about restoring all the debug state, and ptrace doesn't have to
 528  * find every occurrence of the TF bit that could be saved away even
 529  * by user code)
 530  *
 531  * May run on IST stack.
 532  */
 533 dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code)
 534 {
 535         struct task_struct *tsk = current;
 536         int user_icebp = 0;
 537         unsigned long dr6;
 538         int si_code;
 539
 540         get_debugreg(dr6, 6);
 541
 542         /* Filter out all the reserved bits which are preset to 1 */
 543         dr6 &= ~DR6_RESERVED;
 544
 545         /*
 546          * If dr6 has no reason to give us about the origin of this trap,
 547          * then it's very likely the result of an icebp/int01 trap.
 548          * User wants a sigtrap for that.
 549          */
 550         if (!dr6 && user_mode(regs))
 551                 user_icebp = 1;
 552
 553         /* Catch kmemcheck conditions first of all! */
 554         if ((dr6 & DR_STEP) && kmemcheck_trap(regs))
 555                 return;
 556
 557         /* DR6 may or may not be cleared by the CPU */
 558         set_debugreg(0, 6);
 559
 560         /*
 561          * The processor cleared BTF, so don't mark that we need it set.
 562          */
 563         clear_tsk_thread_flag(tsk, TIF_BLOCKSTEP);
 564
 565         /* Store the virtualized DR6 value */
 566         tsk->thread.debugreg6 = dr6;
 567
 568         if (notify_die(DIE_DEBUG, "debug", regs, PTR_ERR(&dr6), error_code,
 569                                                         SIGTRAP) == NOTIFY_STOP)
 570                 return;
 571
 572         /* It's safe to allow irq's after DR6 has been saved */
 573         preempt_conditional_sti(regs);
 574
 575         if (regs->flags & X86_VM_MASK) {
 576                 handle_vm86_trap((struct kernel_vm86_regs *) regs,
 577                                 error_code, 1);
 578                 return;
 579         }
 580
 581         /*
 582          * Single-stepping through system calls: ignore any exceptions in
 583          * kernel space, but re-enable TF when returning to user mode.
 584          *
 585          * We already checked v86 mode above, so we can check for kernel mode
 586          * by just checking the CPL of CS.
 587          */
 588         if ((dr6 & DR_STEP) && !user_mode(regs)) {
 589                 tsk->thread.debugreg6 &= ~DR_STEP;
 590                 set_tsk_thread_flag(tsk, TIF_SINGLESTEP);
 591                 regs->flags &= ~X86_EFLAGS_TF;
 592         }
 593         si_code = get_si_code(tsk->thread.debugreg6);
 594         if (tsk->thread.debugreg6 & (DR_STEP | DR_TRAP_BITS) || user_icebp)
 595                 send_sigtrap(tsk, regs, error_code, si_code);
 596         preempt_conditional_cli(regs);
 597
 598         return;
 599 }
 600
 601 /*
 602  * Note that we play around with the 'TS' bit in an attempt to get
 603  * the correct behaviour even in the presence of the asynchronous
 604  * IRQ13 behaviour
 605  */
 606 void math_error(struct pt_regs *regs, int error_code, int trapnr)
 607 {
 608         struct task_struct *task = current;
 609         siginfo_t info;
 610         unsigned short err;
 611         char *str = (trapnr == 16) ? "fpu exception" : "simd exception";
 612
 613         if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, SIGFPE) == NOTIFY_STOP)
 614                 return;
 615         conditional_sti(regs);
 616
 617         if (!user_mode_vm(regs))
 618         {
 619                 if (!fixup_exception(regs)) {
 620                         task->thread.error_code = error_code;
 621                         task->thread.trap_no = trapnr;
 622                         die(str, regs, error_code);
 623                 }
 624                 return;
 625         }
 626
 627         /*
 628          * Save the info for the exception handler and clear the error.
 629          */
 630         save_init_fpu(task);
 631         task->thread.trap_no = trapnr;
 632         task->thread.error_code = error_code;
 633         info.si_signo = SIGFPE;
 634         info.si_errno = 0;
 635         info.si_addr = (void __user *)regs->ip;
 636         if (trapnr == 16) {
 637                 unsigned short cwd, swd;
 638                 /*
 639                  * (~cwd & swd) will mask out exceptions that are not set to unmasked
 640                  * status.  0x3f is the exception bits in these regs, 0x200 is the
 641                  * C1 reg you need in case of a stack fault, 0x040 is the stack
 642                  * fault bit.  We should only be taking one exception at a time,
 643                  * so if this combination doesn't produce any single exception,
 644                  * then we have a bad program that isn't synchronizing its FPU usage
 645                  * and it will suffer the consequences since we won't be able to
 646                  * fully reproduce the context of the exception
 647                  */
 648                 cwd = get_fpu_cwd(task);
 649                 swd = get_fpu_swd(task);
 650
 651                 err = swd & ~cwd;
 652         } else {
 653                 /*
 654                  * The SIMD FPU exceptions are handled a little differently, as there
 655                  * is only a single status/control register.  Thus, to determine which
 656                  * unmasked exception was caught we must mask the exception mask bits
 657                  * at 0x1f80, and then use these to mask the exception bits at 0x3f.
 658                  */
 659                 unsigned short mxcsr = get_fpu_mxcsr(task);
 660                 err = ~(mxcsr >> 7) & mxcsr;
 661         }
 662
 663         if (err & 0x001) {      /* Invalid op */
 664                 /*
 665                  * swd & 0x240 == 0x040: Stack Underflow
 666                  * swd & 0x240 == 0x240: Stack Overflow
 667                  * User must clear the SF bit (0x40) if set
 668                  */
 669                 info.si_code = FPE_FLTINV;
 670         } else if (err & 0x004) { /* Divide by Zero */
 671                 info.si_code = FPE_FLTDIV;
 672         } else if (err & 0x008) { /* Overflow */
 673                 info.si_code = FPE_FLTOVF;
 674         } else if (err & 0x012) { /* Denormal, Underflow */
 675                 info.si_code = FPE_FLTUND;
 676         } else if (err & 0x020) { /* Precision */
 677                 info.si_code = FPE_FLTRES;
 678         } else {
 679                 /*
 680                  * If we're using IRQ 13, or supposedly even some trap 16
 681                  * implementations, it's possible we get a spurious trap...
 682                  */
 683                 return;         /* Spurious trap, no error */
 684         }
 685         force_sig_info(SIGFPE, &info, task);
 686 }
 687
 688 dotraplinkage void do_coprocessor_error(struct pt_regs *regs, long error_code)
 689 {
 690 #ifdef CONFIG_X86_32
 691         ignore_fpu_irq = 1;
 692 #endif
 693
 694         math_error(regs, error_code, 16);
 695 }
 696
 697 dotraplinkage void
 698 do_simd_coprocessor_error(struct pt_regs *regs, long error_code)
 699 {
 700         math_error(regs, error_code, 19);
 701 }
 702
 703 dotraplinkage void
 704 do_spurious_interrupt_bug(struct pt_regs *regs, long error_code)
 705 {
 706         conditional_sti(regs);
 707 #if 0
 708         /* No need to warn about this any longer. */
 709         printk(KERN_INFO "Ignoring P6 Local APIC Spurious Interrupt Bug...\n");
 710 #endif
 711 }
 712
 713 asmlinkage void __attribute__((weak)) smp_thermal_interrupt(void)
 714 {
 715 }
 716
 717 asmlinkage void __attribute__((weak)) smp_threshold_interrupt(void)
 718 {
 719 }
 720
 721 /*
 722  * __math_state_restore assumes that cr0.TS is already clear and the
 723  * fpu state is all ready for use.  Used during context switch.
 724  */
 725 void __math_state_restore(void)
 726 {
 727         struct thread_info *thread = current_thread_info();
 728         struct task_struct *tsk = thread->task;
 729
 730         /*
 731          * Paranoid restore. send a SIGSEGV if we fail to restore the state.
 732          */
 733         if (unlikely(restore_fpu_checking(tsk))) {
 734                 stts();
 735                 force_sig(SIGSEGV, tsk);
 736                 return;
 737         }
 738
 739         thread->status |= TS_USEDFPU;   /* So we fnsave on switch_to() */
 740         tsk->fpu_counter++;
 741 }
 742
 743 /*
 744  * 'math_state_restore()' saves the current math information in the
 745  * old math state array, and gets the new ones from the current task
 746  *
 747  * Careful.. There are problems with IBM-designed IRQ13 behaviour.
 748  * Don't touch unless you *really* know how it works.
 749  *
 750  * Must be called with kernel preemption disabled (in this case,
 751  * local interrupts are disabled at the call-site in entry.S).
 752  */
 753 asmlinkage void math_state_restore(void)
 754 {
 755         struct thread_info *thread = current_thread_info();
 756         struct task_struct *tsk = thread->task;
 757
 758         if (!tsk_used_math(tsk)) {
 759                 local_irq_enable();
 760                 /*
 761                  * does a slab alloc which can sleep
 762                  */
 763                 if (init_fpu(tsk)) {
 764                         /*
 765                          * ran out of memory!
 766                          */
 767                         do_group_exit(SIGKILL);
 768                         return;
 769                 }
 770                 local_irq_disable();
 771         }
 772
 773         clts();                         /* Allow maths ops (or we recurse) */
 774
 775         __math_state_restore();
 776 }
 777 EXPORT_SYMBOL_GPL(math_state_restore);
 778
 779 #ifndef CONFIG_MATH_EMULATION
 780 void math_emulate(struct math_emu_info *info)
 781 {
 782         printk(KERN_EMERG
 783                 "math-emulation not enabled and no coprocessor found.\n");
 784         printk(KERN_EMERG "killing %s.\n", current->comm);
 785         force_sig(SIGFPE, current);
 786         schedule();
 787 }
 788 #endif /* CONFIG_MATH_EMULATION */
 789
 790 dotraplinkage void __kprobes
 791 do_device_not_available(struct pt_regs *regs, long error_code)
 792 {
 793 #ifdef CONFIG_X86_32
 794         if (read_cr0() & X86_CR0_EM) {
 795                 struct math_emu_info info = { };
 796
 797                 conditional_sti(regs);
 798
 799                 info.regs = regs;
 800                 math_emulate(&info);
 801         } else {
 802                 math_state_restore(); /* interrupts still off */
 803                 conditional_sti(regs);
 804         }
 805 #else
 806         math_state_restore();
 807 #endif
 808 }
 809
 810 #ifdef CONFIG_X86_32
 811 dotraplinkage void do_iret_error(struct pt_regs *regs, long error_code)
 812 {
 813         siginfo_t info;
 814         local_irq_enable();
 815
 816         info.si_signo = SIGILL;
 817         info.si_errno = 0;
 818         info.si_code = ILL_BADSTK;
 819         info.si_addr = NULL;
 820         if (notify_die(DIE_TRAP, "iret exception",
 821                         regs, error_code, 32, SIGILL) == NOTIFY_STOP)
 822                 return;
 823         do_trap(32, SIGILL, "iret exception", regs, error_code, &info);
 824 }
 825 #endif
 826
 827 /* Set of traps needed for early debugging. */
 828 void __init early_trap_init(void)
 829 {
 830         set_intr_gate_ist(1, &debug, DEBUG_STACK);
 831         /* int3 can be called from all */
 832         set_system_intr_gate_ist(3, &int3, DEBUG_STACK);
 833         set_intr_gate(14, &page_fault);
 834         load_idt(&idt_descr);
 835 }
 836
 837 void __init trap_init(void)
 838 {
 839         int i;
 840
 841 #ifdef CONFIG_EISA
 842         void __iomem *p = early_ioremap(0x0FFFD9, 4);
 843
 844         if (readl(p) == 'E' + ('I'<<8) + ('S'<<16) + ('A'<<24))
 845                 EISA_bus = 1;
 846         early_iounmap(p, 4);
 847 #endif
 848
 849         set_intr_gate(0, &divide_error);
 850         set_intr_gate_ist(2, &nmi, NMI_STACK);
 851         /* int4 can be called from all */
 852         set_system_intr_gate(4, &overflow);
 853         set_intr_gate(5, &bounds);
 854         set_intr_gate(6, &invalid_op);
 855         set_intr_gate(7, &device_not_available);
 856 #ifdef CONFIG_X86_32
 857         set_task_gate(8, GDT_ENTRY_DOUBLEFAULT_TSS);
 858 #else
 859         set_intr_gate_ist(8, &double_fault, DOUBLEFAULT_STACK);
 860 #endif
 861         set_intr_gate(9, &coprocessor_segment_overrun);
 862         set_intr_gate(10, &invalid_TSS);
 863         set_intr_gate(11, &segment_not_present);
 864         set_intr_gate_ist(12, &stack_segment, STACKFAULT_STACK);
 865         set_intr_gate(13, &general_protection);
 866         set_intr_gate(15, &spurious_interrupt_bug);
 867         set_intr_gate(16, &coprocessor_error);
 868         set_intr_gate(17, &alignment_check);
 869 #ifdef CONFIG_X86_MCE
 870         set_intr_gate_ist(18, &machine_check, MCE_STACK);
 871 #endif
 872         set_intr_gate(19, &simd_coprocessor_error);
 873
 874         /* Reserve all the builtin and the syscall vector: */
 875         for (i = 0; i < FIRST_EXTERNAL_VECTOR; i++)
 876                 set_bit(i, used_vectors);
 877
 878 #ifdef CONFIG_IA32_EMULATION
 879         set_system_intr_gate(IA32_SYSCALL_VECTOR, ia32_syscall);
 880         set_bit(IA32_SYSCALL_VECTOR, used_vectors);
 881 #endif
 882
 883 #ifdef CONFIG_X86_32
 884         set_system_trap_gate(SYSCALL_VECTOR, &system_call);
 885         set_bit(SYSCALL_VECTOR, used_vectors);
 886 #endif
 887
 888         /*
 889          * Should be a barrier for any external CPU state:
 890          */
 891         cpu_init();
 892
 893         x86_init.irqs.trap_init();
 894 }