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 <linux/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 int unknown_nmi_panic;
  87 /*
  88  * Prevent NMI reason port (0x61) being accessed simultaneously, can
  89  * only be used in NMI handler.
  90  */
  91 static DEFINE_RAW_SPINLOCK(nmi_reason_lock);
  92
  93 static inline void conditional_sti(struct pt_regs *regs)
  94 {
  95         if (regs->flags & X86_EFLAGS_IF)
  96                 local_irq_enable();
  97 }
  98
  99 static inline void preempt_conditional_sti(struct pt_regs *regs)
 100 {
 101         inc_preempt_count();
 102         if (regs->flags & X86_EFLAGS_IF)
 103                 local_irq_enable();
 104 }
 105
 106 static inline void conditional_cli(struct pt_regs *regs)
 107 {
 108         if (regs->flags & X86_EFLAGS_IF)
 109                 local_irq_disable();
 110 }
 111
 112 static inline void preempt_conditional_cli(struct pt_regs *regs)
 113 {
 114         if (regs->flags & X86_EFLAGS_IF)
 115                 local_irq_disable();
 116         dec_preempt_count();
 117 }
 118
 119 static void __kprobes
 120 do_trap(int trapnr, int signr, char *str, struct pt_regs *regs,
 121         long error_code, siginfo_t *info)
 122 {
 123         struct task_struct *tsk = current;
 124
 125 #ifdef CONFIG_X86_32
 126         if (regs->flags & X86_VM_MASK) {
 127                 /*
 128                  * traps 0, 1, 3, 4, and 5 should be forwarded to vm86.
 129                  * On nmi (interrupt 2), do_trap should not be called.
 130                  */
 131                 if (trapnr < 6)
 132                         goto vm86_trap;
 133                 goto trap_signal;
 134         }
 135 #endif
 136
 137         if (!user_mode(regs))
 138                 goto kernel_trap;
 139
 140 #ifdef CONFIG_X86_32
 141 trap_signal:
 142 #endif
 143         /*
 144          * We want error_code and trap_no set for userspace faults and
 145          * kernelspace faults which result in die(), but not
 146          * kernelspace faults which are fixed up.  die() gives the
 147          * process no chance to handle the signal and notice the
 148          * kernel fault information, so that won't result in polluting
 149          * the information about previously queued, but not yet
 150          * delivered, faults.  See also do_general_protection below.
 151          */
 152         tsk->thread.error_code = error_code;
 153         tsk->thread.trap_no = trapnr;
 154
 155 #ifdef CONFIG_X86_64
 156         if (show_unhandled_signals && unhandled_signal(tsk, signr) &&
 157             printk_ratelimit()) {
 158                 printk(KERN_INFO
 159                        "%s[%d] trap %s ip:%lx sp:%lx error:%lx",
 160                        tsk->comm, tsk->pid, str,
 161                        regs->ip, regs->sp, error_code);
 162                 print_vma_addr(" in ", regs->ip);
 163                 printk("\n");
 164         }
 165 #endif
 166
 167         if (info)
 168                 force_sig_info(signr, info, tsk);
 169         else
 170                 force_sig(signr, tsk);
 171         return;
 172
 173 kernel_trap:
 174         if (!fixup_exception(regs)) {
 175                 tsk->thread.error_code = error_code;
 176                 tsk->thread.trap_no = trapnr;
 177                 die(str, regs, error_code);
 178         }
 179         return;
 180
 181 #ifdef CONFIG_X86_32
 182 vm86_trap:
 183         if (handle_vm86_trap((struct kernel_vm86_regs *) regs,
 184                                                 error_code, trapnr))
 185                 goto trap_signal;
 186         return;
 187 #endif
 188 }
 189
 190 #define DO_ERROR(trapnr, signr, str, name)                              \
 191 dotraplinkage void do_##name(struct pt_regs *regs, long error_code)     \
 192 {                                                                       \
 193         if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr)  \
 194                                                         == NOTIFY_STOP) \
 195                 return;                                                 \
 196         conditional_sti(regs);                                          \
 197         do_trap(trapnr, signr, str, regs, error_code, NULL);            \
 198 }
 199
 200 #define DO_ERROR_INFO(trapnr, signr, str, name, sicode, siaddr)         \
 201 dotraplinkage void do_##name(struct pt_regs *regs, long error_code)     \
 202 {                                                                       \
 203         siginfo_t info;                                                 \
 204         info.si_signo = signr;                                          \
 205         info.si_errno = 0;                                              \
 206         info.si_code = sicode;                                          \
 207         info.si_addr = (void __user *)siaddr;                           \
 208         if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr)  \
 209                                                         == NOTIFY_STOP) \
 210                 return;                                                 \
 211         conditional_sti(regs);                                          \
 212         do_trap(trapnr, signr, str, regs, error_code, &info);           \
 213 }
 214
 215 DO_ERROR_INFO(0, SIGFPE, "divide error", divide_error, FPE_INTDIV, regs->ip)
 216 DO_ERROR(4, SIGSEGV, "overflow", overflow)
 217 DO_ERROR(5, SIGSEGV, "bounds", bounds)
 218 DO_ERROR_INFO(6, SIGILL, "invalid opcode", invalid_op, ILL_ILLOPN, regs->ip)
 219 DO_ERROR(9, SIGFPE, "coprocessor segment overrun", coprocessor_segment_overrun)
 220 DO_ERROR(10, SIGSEGV, "invalid TSS", invalid_TSS)
 221 DO_ERROR(11, SIGBUS, "segment not present", segment_not_present)
 222 #ifdef CONFIG_X86_32
 223 DO_ERROR(12, SIGBUS, "stack segment", stack_segment)
 224 #endif
 225 DO_ERROR_INFO(17, SIGBUS, "alignment check", alignment_check, BUS_ADRALN, 0)
 226
 227 #ifdef CONFIG_X86_64
 228 /* Runs on IST stack */
 229 dotraplinkage void do_stack_segment(struct pt_regs *regs, long error_code)
 230 {
 231         if (notify_die(DIE_TRAP, "stack segment", regs, error_code,
 232                         12, SIGBUS) == NOTIFY_STOP)
 233                 return;
 234         preempt_conditional_sti(regs);
 235         do_trap(12, SIGBUS, "stack segment", regs, error_code, NULL);
 236         preempt_conditional_cli(regs);
 237 }
 238
 239 dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code)
 240 {
 241         static const char str[] = "double fault";
 242         struct task_struct *tsk = current;
 243
 244         /* Return not checked because double check cannot be ignored */
 245         notify_die(DIE_TRAP, str, regs, error_code, 8, SIGSEGV);
 246
 247         tsk->thread.error_code = error_code;
 248         tsk->thread.trap_no = 8;
 249
 250         /*
 251          * This is always a kernel trap and never fixable (and thus must
 252          * never return).
 253          */
 254         for (;;)
 255                 die(str, regs, error_code);
 256 }
 257 #endif
 258
 259 dotraplinkage void __kprobes
 260 do_general_protection(struct pt_regs *regs, long error_code)
 261 {
 262         struct task_struct *tsk;
 263
 264         conditional_sti(regs);
 265
 266 #ifdef CONFIG_X86_32
 267         if (regs->flags & X86_VM_MASK)
 268                 goto gp_in_vm86;
 269 #endif
 270
 271         tsk = current;
 272         if (!user_mode(regs))
 273                 goto gp_in_kernel;
 274
 275         tsk->thread.error_code = error_code;
 276         tsk->thread.trap_no = 13;
 277
 278         if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) &&
 279                         printk_ratelimit()) {
 280                 printk(KERN_INFO
 281                         "%s[%d] general protection ip:%lx sp:%lx error:%lx",
 282                         tsk->comm, task_pid_nr(tsk),
 283                         regs->ip, regs->sp, error_code);
 284                 print_vma_addr(" in ", regs->ip);
 285                 printk("\n");
 286         }
 287
 288         force_sig(SIGSEGV, tsk);
 289         return;
 290
 291 #ifdef CONFIG_X86_32
 292 gp_in_vm86:
 293         local_irq_enable();
 294         handle_vm86_fault((struct kernel_vm86_regs *) regs, error_code);
 295         return;
 296 #endif
 297
 298 gp_in_kernel:
 299         if (fixup_exception(regs))
 300                 return;
 301
 302         tsk->thread.error_code = error_code;
 303         tsk->thread.trap_no = 13;
 304         if (notify_die(DIE_GPF, "general protection fault", regs,
 305                                 error_code, 13, SIGSEGV) == NOTIFY_STOP)
 306                 return;
 307         die("general protection fault", regs, error_code);
 308 }
 309
 310 static int __init setup_unknown_nmi_panic(char *str)
 311 {
 312         unknown_nmi_panic = 1;
 313         return 1;
 314 }
 315 __setup("unknown_nmi_panic", setup_unknown_nmi_panic);
 316
 317 static notrace __kprobes void
 318 pci_serr_error(unsigned char reason, struct pt_regs *regs)
 319 {
 320         pr_emerg("NMI: PCI system error (SERR) for reason %02x on CPU %d.\n",
 321                  reason, smp_processor_id());
 322
 323         /*
 324          * On some machines, PCI SERR line is used to report memory
 325          * errors. EDAC makes use of it.
 326          */
 327 #if defined(CONFIG_EDAC)
 328         if (edac_handler_set()) {
 329                 edac_atomic_assert_error();
 330                 return;
 331         }
 332 #endif
 333
 334         if (panic_on_unrecovered_nmi)
 335                 panic("NMI: Not continuing");
 336
 337         pr_emerg("Dazed and confused, but trying to continue\n");
 338
 339         /* Clear and disable the PCI SERR error line. */
 340         reason = (reason & NMI_REASON_CLEAR_MASK) | NMI_REASON_CLEAR_SERR;
 341         outb(reason, NMI_REASON_PORT);
 342 }
 343
 344 static notrace __kprobes void
 345 io_check_error(unsigned char reason, struct pt_regs *regs)
 346 {
 347         unsigned long i;
 348
 349         pr_emerg(
 350         "NMI: IOCK error (debug interrupt?) for reason %02x on CPU %d.\n",
 351                  reason, smp_processor_id());
 352         show_registers(regs);
 353
 354         if (panic_on_io_nmi)
 355                 panic("NMI IOCK error: Not continuing");
 356
 357         /* Re-enable the IOCK line, wait for a few seconds */
 358         reason = (reason & NMI_REASON_CLEAR_MASK) | NMI_REASON_CLEAR_IOCHK;
 359         outb(reason, NMI_REASON_PORT);
 360
 361         i = 20000;
 362         while (--i) {
 363                 touch_nmi_watchdog();
 364                 udelay(100);
 365         }
 366
 367         reason &= ~NMI_REASON_CLEAR_IOCHK;
 368         outb(reason, NMI_REASON_PORT);
 369 }
 370
 371 static notrace __kprobes void
 372 unknown_nmi_error(unsigned char reason, struct pt_regs *regs)
 373 {
 374         if (notify_die(DIE_NMIUNKNOWN, "nmi", regs, reason, 2, SIGINT) ==
 375                         NOTIFY_STOP)
 376                 return;
 377 #ifdef CONFIG_MCA
 378         /*
 379          * Might actually be able to figure out what the guilty party
 380          * is:
 381          */
 382         if (MCA_bus) {
 383                 mca_handle_nmi();
 384                 return;
 385         }
 386 #endif
 387         pr_emerg("Uhhuh. NMI received for unknown reason %02x on CPU %d.\n",
 388                  reason, smp_processor_id());
 389
 390         pr_emerg("Do you have a strange power saving mode enabled?\n");
 391         if (unknown_nmi_panic || panic_on_unrecovered_nmi)
 392                 panic("NMI: Not continuing");
 393
 394         pr_emerg("Dazed and confused, but trying to continue\n");
 395 }
 396
 397 static notrace __kprobes void default_do_nmi(struct pt_regs *regs)
 398 {
 399         unsigned char reason = 0;
 400
 401         /*
 402          * CPU-specific NMI must be processed before non-CPU-specific
 403          * NMI, otherwise we may lose it, because the CPU-specific
 404          * NMI can not be detected/processed on other CPUs.
 405          */
 406         if (notify_die(DIE_NMI, "nmi", regs, 0, 2, SIGINT) == NOTIFY_STOP)
 407                 return;
 408
 409         /* Non-CPU-specific NMI: NMI sources can be processed on any CPU */
 410         raw_spin_lock(&nmi_reason_lock);
 411         reason = get_nmi_reason();
 412
 413         if (reason & NMI_REASON_MASK) {
 414                 if (reason & NMI_REASON_SERR)
 415                         pci_serr_error(reason, regs);
 416                 else if (reason & NMI_REASON_IOCHK)
 417                         io_check_error(reason, regs);
 418 #ifdef CONFIG_X86_32
 419                 /*
 420                  * Reassert NMI in case it became active
 421                  * meanwhile as it's edge-triggered:
 422                  */
 423                 reassert_nmi();
 424 #endif
 425                 raw_spin_unlock(&nmi_reason_lock);
 426                 return;
 427         }
 428         raw_spin_unlock(&nmi_reason_lock);
 429
 430         unknown_nmi_error(reason, regs);
 431 }
 432
 433 dotraplinkage notrace __kprobes void
 434 do_nmi(struct pt_regs *regs, long error_code)
 435 {
 436         nmi_enter();
 437
 438         inc_irq_stat(__nmi_count);
 439
 440         if (!ignore_nmis)
 441                 default_do_nmi(regs);
 442
 443         nmi_exit();
 444 }
 445
 446 void stop_nmi(void)
 447 {
 448         ignore_nmis++;
 449 }
 450
 451 void restart_nmi(void)
 452 {
 453         ignore_nmis--;
 454 }
 455
 456 /* May run on IST stack. */
 457 dotraplinkage void __kprobes do_int3(struct pt_regs *regs, long error_code)
 458 {
 459 #ifdef CONFIG_KGDB_LOW_LEVEL_TRAP
 460         if (kgdb_ll_trap(DIE_INT3, "int3", regs, error_code, 3, SIGTRAP)
 461                         == NOTIFY_STOP)
 462                 return;
 463 #endif /* CONFIG_KGDB_LOW_LEVEL_TRAP */
 464 #ifdef CONFIG_KPROBES
 465         if (notify_die(DIE_INT3, "int3", regs, error_code, 3, SIGTRAP)
 466                         == NOTIFY_STOP)
 467                 return;
 468 #else
 469         if (notify_die(DIE_TRAP, "int3", regs, error_code, 3, SIGTRAP)
 470                         == NOTIFY_STOP)
 471                 return;
 472 #endif
 473
 474         preempt_conditional_sti(regs);
 475         do_trap(3, SIGTRAP, "int3", regs, error_code, NULL);
 476         preempt_conditional_cli(regs);
 477 }
 478
 479 #ifdef CONFIG_X86_64
 480 /*
 481  * Help handler running on IST stack to switch back to user stack
 482  * for scheduling or signal handling. The actual stack switch is done in
 483  * entry.S
 484  */
 485 asmlinkage __kprobes struct pt_regs *sync_regs(struct pt_regs *eregs)
 486 {
 487         struct pt_regs *regs = eregs;
 488         /* Did already sync */
 489         if (eregs == (struct pt_regs *)eregs->sp)
 490                 ;
 491         /* Exception from user space */
 492         else if (user_mode(eregs))
 493                 regs = task_pt_regs(current);
 494         /*
 495          * Exception from kernel and interrupts are enabled. Move to
 496          * kernel process stack.
 497          */
 498         else if (eregs->flags & X86_EFLAGS_IF)
 499                 regs = (struct pt_regs *)(eregs->sp -= sizeof(struct pt_regs));
 500         if (eregs != regs)
 501                 *regs = *eregs;
 502         return regs;
 503 }
 504 #endif
 505
 506 /*
 507  * Our handling of the processor debug registers is non-trivial.
 508  * We do not clear them on entry and exit from the kernel. Therefore
 509  * it is possible to get a watchpoint trap here from inside the kernel.
 510  * However, the code in ./ptrace.c has ensured that the user can
 511  * only set watchpoints on userspace addresses. Therefore the in-kernel
 512  * watchpoint trap can only occur in code which is reading/writing
 513  * from user space. Such code must not hold kernel locks (since it
 514  * can equally take a page fault), therefore it is safe to call
 515  * force_sig_info even though that claims and releases locks.
 516  *
 517  * Code in ./signal.c ensures that the debug control register
 518  * is restored before we deliver any signal, and therefore that
 519  * user code runs with the correct debug control register even though
 520  * we clear it here.
 521  *
 522  * Being careful here means that we don't have to be as careful in a
 523  * lot of more complicated places (task switching can be a bit lazy
 524  * about restoring all the debug state, and ptrace doesn't have to
 525  * find every occurrence of the TF bit that could be saved away even
 526  * by user code)
 527  *
 528  * May run on IST stack.
 529  */
 530 dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code)
 531 {
 532         struct task_struct *tsk = current;
 533         int user_icebp = 0;
 534         unsigned long dr6;
 535         int si_code;
 536
 537         get_debugreg(dr6, 6);
 538
 539         /* Filter out all the reserved bits which are preset to 1 */
 540         dr6 &= ~DR6_RESERVED;
 541
 542         /*
 543          * If dr6 has no reason to give us about the origin of this trap,
 544          * then it's very likely the result of an icebp/int01 trap.
 545          * User wants a sigtrap for that.
 546          */
 547         if (!dr6 && user_mode(regs))
 548                 user_icebp = 1;
 549
 550         /* Catch kmemcheck conditions first of all! */
 551         if ((dr6 & DR_STEP) && kmemcheck_trap(regs))
 552                 return;
 553
 554         /* DR6 may or may not be cleared by the CPU */
 555         set_debugreg(0, 6);
 556
 557         /*
 558          * The processor cleared BTF, so don't mark that we need it set.
 559          */
 560         clear_tsk_thread_flag(tsk, TIF_BLOCKSTEP);
 561
 562         /* Store the virtualized DR6 value */
 563         tsk->thread.debugreg6 = dr6;
 564
 565         if (notify_die(DIE_DEBUG, "debug", regs, PTR_ERR(&dr6), error_code,
 566                                                         SIGTRAP) == NOTIFY_STOP)
 567                 return;
 568
 569         /* It's safe to allow irq's after DR6 has been saved */
 570         preempt_conditional_sti(regs);
 571
 572         if (regs->flags & X86_VM_MASK) {
 573                 handle_vm86_trap((struct kernel_vm86_regs *) regs,
 574                                 error_code, 1);
 575                 preempt_conditional_cli(regs);
 576                 return;
 577         }
 578
 579         /*
 580          * Single-stepping through system calls: ignore any exceptions in
 581          * kernel space, but re-enable TF when returning to user mode.
 582          *
 583          * We already checked v86 mode above, so we can check for kernel mode
 584          * by just checking the CPL of CS.
 585          */
 586         if ((dr6 & DR_STEP) && !user_mode(regs)) {
 587                 tsk->thread.debugreg6 &= ~DR_STEP;
 588                 set_tsk_thread_flag(tsk, TIF_SINGLESTEP);
 589                 regs->flags &= ~X86_EFLAGS_TF;
 590         }
 591         si_code = get_si_code(tsk->thread.debugreg6);
 592         if (tsk->thread.debugreg6 & (DR_STEP | DR_TRAP_BITS) || user_icebp)
 593                 send_sigtrap(tsk, regs, error_code, si_code);
 594         preempt_conditional_cli(regs);
 595
 596         return;
 597 }
 598
 599 /*
 600  * Note that we play around with the 'TS' bit in an attempt to get
 601  * the correct behaviour even in the presence of the asynchronous
 602  * IRQ13 behaviour
 603  */
 604 void math_error(struct pt_regs *regs, int error_code, int trapnr)
 605 {
 606         struct task_struct *task = current;
 607         siginfo_t info;
 608         unsigned short err;
 609         char *str = (trapnr == 16) ? "fpu exception" : "simd exception";
 610
 611         if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, SIGFPE) == NOTIFY_STOP)
 612                 return;
 613         conditional_sti(regs);
 614
 615         if (!user_mode_vm(regs))
 616         {
 617                 if (!fixup_exception(regs)) {
 618                         task->thread.error_code = error_code;
 619                         task->thread.trap_no = trapnr;
 620                         die(str, regs, error_code);
 621                 }
 622                 return;
 623         }
 624
 625         /*
 626          * Save the info for the exception handler and clear the error.
 627          */
 628         save_init_fpu(task);
 629         task->thread.trap_no = trapnr;
 630         task->thread.error_code = error_code;
 631         info.si_signo = SIGFPE;
 632         info.si_errno = 0;
 633         info.si_addr = (void __user *)regs->ip;
 634         if (trapnr == 16) {
 635                 unsigned short cwd, swd;
 636                 /*
 637                  * (~cwd & swd) will mask out exceptions that are not set to unmasked
 638                  * status.  0x3f is the exception bits in these regs, 0x200 is the
 639                  * C1 reg you need in case of a stack fault, 0x040 is the stack
 640                  * fault bit.  We should only be taking one exception at a time,
 641                  * so if this combination doesn't produce any single exception,
 642                  * then we have a bad program that isn't synchronizing its FPU usage
 643                  * and it will suffer the consequences since we won't be able to
 644                  * fully reproduce the context of the exception
 645                  */
 646                 cwd = get_fpu_cwd(task);
 647                 swd = get_fpu_swd(task);
 648
 649                 err = swd & ~cwd;
 650         } else {
 651                 /*
 652                  * The SIMD FPU exceptions are handled a little differently, as there
 653                  * is only a single status/control register.  Thus, to determine which
 654                  * unmasked exception was caught we must mask the exception mask bits
 655                  * at 0x1f80, and then use these to mask the exception bits at 0x3f.
 656                  */
 657                 unsigned short mxcsr = get_fpu_mxcsr(task);
 658                 err = ~(mxcsr >> 7) & mxcsr;
 659         }
 660
 661         if (err & 0x001) {      /* Invalid op */
 662                 /*
 663                  * swd & 0x240 == 0x040: Stack Underflow
 664                  * swd & 0x240 == 0x240: Stack Overflow
 665                  * User must clear the SF bit (0x40) if set
 666                  */
 667                 info.si_code = FPE_FLTINV;
 668         } else if (err & 0x004) { /* Divide by Zero */
 669                 info.si_code = FPE_FLTDIV;
 670         } else if (err & 0x008) { /* Overflow */
 671                 info.si_code = FPE_FLTOVF;
 672         } else if (err & 0x012) { /* Denormal, Underflow */
 673                 info.si_code = FPE_FLTUND;
 674         } else if (err & 0x020) { /* Precision */
 675                 info.si_code = FPE_FLTRES;
 676         } else {
 677                 /*
 678                  * If we're using IRQ 13, or supposedly even some trap 16
 679                  * implementations, it's possible we get a spurious trap...
 680                  */
 681                 return;         /* Spurious trap, no error */
 682         }
 683         force_sig_info(SIGFPE, &info, task);
 684 }
 685
 686 dotraplinkage void do_coprocessor_error(struct pt_regs *regs, long error_code)
 687 {
 688 #ifdef CONFIG_X86_32
 689         ignore_fpu_irq = 1;
 690 #endif
 691
 692         math_error(regs, error_code, 16);
 693 }
 694
 695 dotraplinkage void
 696 do_simd_coprocessor_error(struct pt_regs *regs, long error_code)
 697 {
 698         math_error(regs, error_code, 19);
 699 }
 700
 701 dotraplinkage void
 702 do_spurious_interrupt_bug(struct pt_regs *regs, long error_code)
 703 {
 704         conditional_sti(regs);
 705 #if 0
 706         /* No need to warn about this any longer. */
 707         printk(KERN_INFO "Ignoring P6 Local APIC Spurious Interrupt Bug...\n");
 708 #endif
 709 }
 710
 711 asmlinkage void __attribute__((weak)) smp_thermal_interrupt(void)
 712 {
 713 }
 714
 715 asmlinkage void __attribute__((weak)) smp_threshold_interrupt(void)
 716 {
 717 }
 718
 719 /*
 720  * __math_state_restore assumes that cr0.TS is already clear and the
 721  * fpu state is all ready for use.  Used during context switch.
 722  */
 723 void __math_state_restore(void)
 724 {
 725         struct thread_info *thread = current_thread_info();
 726         struct task_struct *tsk = thread->task;
 727
 728         /*
 729          * Paranoid restore. send a SIGSEGV if we fail to restore the state.
 730          */
 731         if (unlikely(restore_fpu_checking(tsk))) {
 732                 stts();
 733                 force_sig(SIGSEGV, tsk);
 734                 return;
 735         }
 736
 737         thread->status |= TS_USEDFPU;   /* So we fnsave on switch_to() */
 738         tsk->fpu_counter++;
 739 }
 740
 741 /*
 742  * 'math_state_restore()' saves the current math information in the
 743  * old math state array, and gets the new ones from the current task
 744  *
 745  * Careful.. There are problems with IBM-designed IRQ13 behaviour.
 746  * Don't touch unless you *really* know how it works.
 747  *
 748  * Must be called with kernel preemption disabled (in this case,
 749  * local interrupts are disabled at the call-site in entry.S).
 750  */
 751 asmlinkage void math_state_restore(void)
 752 {
 753         struct thread_info *thread = current_thread_info();
 754         struct task_struct *tsk = thread->task;
 755
 756         if (!tsk_used_math(tsk)) {
 757                 local_irq_enable();
 758                 /*
 759                  * does a slab alloc which can sleep
 760                  */
 761                 if (init_fpu(tsk)) {
 762                         /*
 763                          * ran out of memory!
 764                          */
 765                         do_group_exit(SIGKILL);
 766                         return;
 767                 }
 768                 local_irq_disable();
 769         }
 770
 771         clts();                         /* Allow maths ops (or we recurse) */
 772
 773         __math_state_restore();
 774 }
 775 EXPORT_SYMBOL_GPL(math_state_restore);
 776
 777 dotraplinkage void __kprobes
 778 do_device_not_available(struct pt_regs *regs, long error_code)
 779 {
 780 #ifdef CONFIG_MATH_EMULATION
 781         if (read_cr0() & X86_CR0_EM) {
 782                 struct math_emu_info info = { };
 783
 784                 conditional_sti(regs);
 785
 786                 info.regs = regs;
 787                 math_emulate(&info);
 788                 return;
 789         }
 790 #endif
 791         math_state_restore(); /* interrupts still off */
 792 #ifdef CONFIG_X86_32
 793         conditional_sti(regs);
 794 #endif
 795 }
 796
 797 #ifdef CONFIG_X86_32
 798 dotraplinkage void do_iret_error(struct pt_regs *regs, long error_code)
 799 {
 800         siginfo_t info;
 801         local_irq_enable();
 802
 803         info.si_signo = SIGILL;
 804         info.si_errno = 0;
 805         info.si_code = ILL_BADSTK;
 806         info.si_addr = NULL;
 807         if (notify_die(DIE_TRAP, "iret exception",
 808                         regs, error_code, 32, SIGILL) == NOTIFY_STOP)
 809                 return;
 810         do_trap(32, SIGILL, "iret exception", regs, error_code, &info);
 811 }
 812 #endif
 813
 814 /* Set of traps needed for early debugging. */
 815 void __init early_trap_init(void)
 816 {
 817         set_intr_gate_ist(1, &debug, DEBUG_STACK);
 818         /* int3 can be called from all */
 819         set_system_intr_gate_ist(3, &int3, DEBUG_STACK);
 820         set_intr_gate(14, &page_fault);
 821         load_idt(&idt_descr);
 822 }
 823
 824 void __init trap_init(void)
 825 {
 826         int i;
 827
 828 #ifdef CONFIG_EISA
 829         void __iomem *p = early_ioremap(0x0FFFD9, 4);
 830
 831         if (readl(p) == 'E' + ('I'<<8) + ('S'<<16) + ('A'<<24))
 832                 EISA_bus = 1;
 833         early_iounmap(p, 4);
 834 #endif
 835
 836         set_intr_gate(0, &divide_error);
 837         set_intr_gate_ist(2, &nmi, NMI_STACK);
 838         /* int4 can be called from all */
 839         set_system_intr_gate(4, &overflow);
 840         set_intr_gate(5, &bounds);
 841         set_intr_gate(6, &invalid_op);
 842         set_intr_gate(7, &device_not_available);
 843 #ifdef CONFIG_X86_32
 844         set_task_gate(8, GDT_ENTRY_DOUBLEFAULT_TSS);
 845 #else
 846         set_intr_gate_ist(8, &double_fault, DOUBLEFAULT_STACK);
 847 #endif
 848         set_intr_gate(9, &coprocessor_segment_overrun);
 849         set_intr_gate(10, &invalid_TSS);
 850         set_intr_gate(11, &segment_not_present);
 851         set_intr_gate_ist(12, &stack_segment, STACKFAULT_STACK);
 852         set_intr_gate(13, &general_protection);
 853         set_intr_gate(15, &spurious_interrupt_bug);
 854         set_intr_gate(16, &coprocessor_error);
 855         set_intr_gate(17, &alignment_check);
 856 #ifdef CONFIG_X86_MCE
 857         set_intr_gate_ist(18, &machine_check, MCE_STACK);
 858 #endif
 859         set_intr_gate(19, &simd_coprocessor_error);
 860
 861         /* Reserve all the builtin and the syscall vector: */
 862         for (i = 0; i < FIRST_EXTERNAL_VECTOR; i++)
 863                 set_bit(i, used_vectors);
 864
 865 #ifdef CONFIG_IA32_EMULATION
 866         set_system_intr_gate(IA32_SYSCALL_VECTOR, ia32_syscall);
 867         set_bit(IA32_SYSCALL_VECTOR, used_vectors);
 868 #endif
 869
 870 #ifdef CONFIG_X86_32
 871         set_system_trap_gate(SYSCALL_VECTOR, &system_call);
 872         set_bit(SYSCALL_VECTOR, used_vectors);
 873 #endif
 874
 875         /*
 876          * Should be a barrier for any external CPU state:
 877          */
 878         cpu_init();
 879
 880         x86_init.irqs.trap_init();
 881 }