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
  62 #ifdef CONFIG_X86_64
  63 #include <asm/x86_init.h>
  64 #include <asm/pgalloc.h>
  65 #include <asm/proto.h>
  66 #else
  67 #include <asm/processor-flags.h>
  68 #include <asm/setup.h>
  69
  70 asmlinkage int system_call(void);
  71
  72 /*
  73  * The IDT has to be page-aligned to simplify the Pentium
  74  * F0 0F bug workaround.
  75  */
  76 gate_desc idt_table[NR_VECTORS] __page_aligned_data = { { { { 0, 0 } } }, };
  77 #endif
  78
  79 DECLARE_BITMAP(used_vectors, NR_VECTORS);
  80 EXPORT_SYMBOL_GPL(used_vectors);
  81
  82 static inline void conditional_sti(struct pt_regs *regs)
  83 {
  84         if (regs->flags & X86_EFLAGS_IF)
  85                 local_irq_enable();
  86 }
  87
  88 static inline void preempt_conditional_sti(struct pt_regs *regs)
  89 {
  90         inc_preempt_count();
  91         if (regs->flags & X86_EFLAGS_IF)
  92                 local_irq_enable();
  93 }
  94
  95 static inline void conditional_cli(struct pt_regs *regs)
  96 {
  97         if (regs->flags & X86_EFLAGS_IF)
  98                 local_irq_disable();
  99 }
 100
 101 static inline void preempt_conditional_cli(struct pt_regs *regs)
 102 {
 103         if (regs->flags & X86_EFLAGS_IF)
 104                 local_irq_disable();
 105         dec_preempt_count();
 106 }
 107
 108 static int __kprobes
 109 do_trap_no_signal(struct task_struct *tsk, int trapnr, char *str,
 110                   struct pt_regs *regs, long error_code)
 111 {
 112 #ifdef CONFIG_X86_32
 113         if (regs->flags & X86_VM_MASK) {
 114                 /*
 115                  * Traps 0, 1, 3, 4, and 5 should be forwarded to vm86.
 116                  * On nmi (interrupt 2), do_trap should not be called.
 117                  */
 118                 if (trapnr < X86_TRAP_UD) {
 119                         if (!handle_vm86_trap((struct kernel_vm86_regs *) regs,
 120                                                 error_code, trapnr))
 121                                 return 0;
 122                 }
 123                 return -1;
 124         }
 125 #endif
 126         if (!user_mode(regs)) {
 127                 if (!fixup_exception(regs)) {
 128                         tsk->thread.error_code = error_code;
 129                         tsk->thread.trap_nr = trapnr;
 130                         die(str, regs, error_code);
 131                 }
 132                 return 0;
 133         }
 134
 135         return -1;
 136 }
 137
 138 static void __kprobes
 139 do_trap(int trapnr, int signr, char *str, struct pt_regs *regs,
 140         long error_code, siginfo_t *info)
 141 {
 142         struct task_struct *tsk = current;
 143
 144
 145         if (!do_trap_no_signal(tsk, trapnr, str, regs, error_code))
 146                 return;
 147         /*
 148          * We want error_code and trap_nr set for userspace faults and
 149          * kernelspace faults which result in die(), but not
 150          * kernelspace faults which are fixed up.  die() gives the
 151          * process no chance to handle the signal and notice the
 152          * kernel fault information, so that won't result in polluting
 153          * the information about previously queued, but not yet
 154          * delivered, faults.  See also do_general_protection below.
 155          */
 156         tsk->thread.error_code = error_code;
 157         tsk->thread.trap_nr = trapnr;
 158
 159 #ifdef CONFIG_X86_64
 160         if (show_unhandled_signals && unhandled_signal(tsk, signr) &&
 161             printk_ratelimit()) {
 162                 pr_info("%s[%d] trap %s ip:%lx sp:%lx error:%lx",
 163                         tsk->comm, tsk->pid, str,
 164                         regs->ip, regs->sp, error_code);
 165                 print_vma_addr(" in ", regs->ip);
 166                 pr_cont("\n");
 167         }
 168 #endif
 169
 170         if (info)
 171                 force_sig_info(signr, info, tsk);
 172         else
 173                 force_sig(signr, tsk);
 174 }
 175
 176 #define DO_ERROR(trapnr, signr, str, name)                              \
 177 dotraplinkage void do_##name(struct pt_regs *regs, long error_code)     \
 178 {                                                                       \
 179         enum ctx_state prev_state;                                      \
 180                                                                         \
 181         prev_state = exception_enter();                                 \
 182         if (notify_die(DIE_TRAP, str, regs, error_code,                 \
 183                         trapnr, signr) == NOTIFY_STOP) {                \
 184                 exception_exit(prev_state);                             \
 185                 return;                                                 \
 186         }                                                               \
 187         conditional_sti(regs);                                          \
 188         do_trap(trapnr, signr, str, regs, error_code, NULL);            \
 189         exception_exit(prev_state);                                     \
 190 }
 191
 192 #define DO_ERROR_INFO(trapnr, signr, str, name, sicode, siaddr)         \
 193 dotraplinkage void do_##name(struct pt_regs *regs, long error_code)     \
 194 {                                                                       \
 195         siginfo_t info;                                                 \
 196         enum ctx_state prev_state;                                      \
 197                                                                         \
 198         info.si_signo = signr;                                          \
 199         info.si_errno = 0;                                              \
 200         info.si_code = sicode;                                          \
 201         info.si_addr = (void __user *)siaddr;                           \
 202         prev_state = exception_enter();                                 \
 203         if (notify_die(DIE_TRAP, str, regs, error_code,                 \
 204                         trapnr, signr) == NOTIFY_STOP) {                \
 205                 exception_exit(prev_state);                             \
 206                 return;                                                 \
 207         }                                                               \
 208         conditional_sti(regs);                                          \
 209         do_trap(trapnr, signr, str, regs, error_code, &info);           \
 210         exception_exit(prev_state);                                     \
 211 }
 212
 213 DO_ERROR_INFO(X86_TRAP_DE, SIGFPE, "divide error", divide_error, FPE_INTDIV,
 214                 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,
 218                 regs->ip)
 219 DO_ERROR(X86_TRAP_OLD_MF, SIGFPE, "coprocessor segment overrun",
 220                 coprocessor_segment_overrun)
 221 DO_ERROR(X86_TRAP_TS, SIGSEGV, "invalid TSS", invalid_TSS)
 222 DO_ERROR(X86_TRAP_NP, SIGBUS, "segment not present", segment_not_present)
 223 #ifdef CONFIG_X86_32
 224 DO_ERROR(X86_TRAP_SS, SIGBUS, "stack segment", stack_segment)
 225 #endif
 226 DO_ERROR_INFO(X86_TRAP_AC, SIGBUS, "alignment check", alignment_check,
 227                 BUS_ADRALN, 0)
 228
 229 #ifdef CONFIG_X86_64
 230 /* Runs on IST stack */
 231 dotraplinkage void do_stack_segment(struct pt_regs *regs, long error_code)
 232 {
 233         enum ctx_state prev_state;
 234
 235         prev_state = exception_enter();
 236         if (notify_die(DIE_TRAP, "stack segment", regs, error_code,
 237                        X86_TRAP_SS, SIGBUS) != NOTIFY_STOP) {
 238                 preempt_conditional_sti(regs);
 239                 do_trap(X86_TRAP_SS, SIGBUS, "stack segment", regs, error_code, NULL);
 240                 preempt_conditional_cli(regs);
 241         }
 242         exception_exit(prev_state);
 243 }
 244
 245 dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code)
 246 {
 247         static const char str[] = "double fault";
 248         struct task_struct *tsk = current;
 249
 250         exception_enter();
 251         /* Return not checked because double check cannot be ignored */
 252         notify_die(DIE_TRAP, str, regs, error_code, X86_TRAP_DF, SIGSEGV);
 253
 254         tsk->thread.error_code = error_code;
 255         tsk->thread.trap_nr = X86_TRAP_DF;
 256
 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         prev_state = exception_enter();
 328 #ifdef CONFIG_KGDB_LOW_LEVEL_TRAP
 329         if (kgdb_ll_trap(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP,
 330                                 SIGTRAP) == NOTIFY_STOP)
 331                 goto exit;
 332 #endif /* CONFIG_KGDB_LOW_LEVEL_TRAP */
 333
 334         if (notify_die(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP,
 335                         SIGTRAP) == NOTIFY_STOP)
 336                 goto exit;
 337
 338         /*
 339          * Let others (NMI) know that the debug stack is in use
 340          * as we may switch to the interrupt stack.
 341          */
 342         debug_stack_usage_inc();
 343         preempt_conditional_sti(regs);
 344         do_trap(X86_TRAP_BP, SIGTRAP, "int3", regs, error_code, NULL);
 345         preempt_conditional_cli(regs);
 346         debug_stack_usage_dec();
 347 exit:
 348         exception_exit(prev_state);
 349 }
 350
 351 #ifdef CONFIG_X86_64
 352 /*
 353  * Help handler running on IST stack to switch back to user stack
 354  * for scheduling or signal handling. The actual stack switch is done in
 355  * entry.S
 356  */
 357 asmlinkage __kprobes struct pt_regs *sync_regs(struct pt_regs *eregs)
 358 {
 359         struct pt_regs *regs = eregs;
 360         /* Did already sync */
 361         if (eregs == (struct pt_regs *)eregs->sp)
 362                 ;
 363         /* Exception from user space */
 364         else if (user_mode(eregs))
 365                 regs = task_pt_regs(current);
 366         /*
 367          * Exception from kernel and interrupts are enabled. Move to
 368          * kernel process stack.
 369          */
 370         else if (eregs->flags & X86_EFLAGS_IF)
 371                 regs = (struct pt_regs *)(eregs->sp -= sizeof(struct pt_regs));
 372         if (eregs != regs)
 373                 *regs = *eregs;
 374         return regs;
 375 }
 376 #endif
 377
 378 /*
 379  * Our handling of the processor debug registers is non-trivial.
 380  * We do not clear them on entry and exit from the kernel. Therefore
 381  * it is possible to get a watchpoint trap here from inside the kernel.
 382  * However, the code in ./ptrace.c has ensured that the user can
 383  * only set watchpoints on userspace addresses. Therefore the in-kernel
 384  * watchpoint trap can only occur in code which is reading/writing
 385  * from user space. Such code must not hold kernel locks (since it
 386  * can equally take a page fault), therefore it is safe to call
 387  * force_sig_info even though that claims and releases locks.
 388  *
 389  * Code in ./signal.c ensures that the debug control register
 390  * is restored before we deliver any signal, and therefore that
 391  * user code runs with the correct debug control register even though
 392  * we clear it here.
 393  *
 394  * Being careful here means that we don't have to be as careful in a
 395  * lot of more complicated places (task switching can be a bit lazy
 396  * about restoring all the debug state, and ptrace doesn't have to
 397  * find every occurrence of the TF bit that could be saved away even
 398  * by user code)
 399  *
 400  * May run on IST stack.
 401  */
 402 dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code)
 403 {
 404         struct task_struct *tsk = current;
 405         enum ctx_state prev_state;
 406         int user_icebp = 0;
 407         unsigned long dr6;
 408         int si_code;
 409
 410         prev_state = exception_enter();
 411
 412         get_debugreg(dr6, 6);
 413
 414         /* Filter out all the reserved bits which are preset to 1 */
 415         dr6 &= ~DR6_RESERVED;
 416
 417         /*
 418          * If dr6 has no reason to give us about the origin of this trap,
 419          * then it's very likely the result of an icebp/int01 trap.
 420          * User wants a sigtrap for that.
 421          */
 422         if (!dr6 && user_mode(regs))
 423                 user_icebp = 1;
 424
 425         /* Catch kmemcheck conditions first of all! */
 426         if ((dr6 & DR_STEP) && kmemcheck_trap(regs))
 427                 goto exit;
 428
 429         /* DR6 may or may not be cleared by the CPU */
 430         set_debugreg(0, 6);
 431
 432         /*
 433          * The processor cleared BTF, so don't mark that we need it set.
 434          */
 435         clear_tsk_thread_flag(tsk, TIF_BLOCKSTEP);
 436
 437         /* Store the virtualized DR6 value */
 438         tsk->thread.debugreg6 = dr6;
 439
 440         if (notify_die(DIE_DEBUG, "debug", regs, PTR_ERR(&dr6), error_code,
 441                                                         SIGTRAP) == NOTIFY_STOP)
 442                 goto exit;
 443
 444         /*
 445          * Let others (NMI) know that the debug stack is in use
 446          * as we may switch to the interrupt stack.
 447          */
 448         debug_stack_usage_inc();
 449
 450         /* It's safe to allow irq's after DR6 has been saved */
 451         preempt_conditional_sti(regs);
 452
 453         if (regs->flags & X86_VM_MASK) {
 454                 handle_vm86_trap((struct kernel_vm86_regs *) regs, error_code,
 455                                         X86_TRAP_DB);
 456                 preempt_conditional_cli(regs);
 457                 debug_stack_usage_dec();
 458                 goto exit;
 459         }
 460
 461         /*
 462          * Single-stepping through system calls: ignore any exceptions in
 463          * kernel space, but re-enable TF when returning to user mode.
 464          *
 465          * We already checked v86 mode above, so we can check for kernel mode
 466          * by just checking the CPL of CS.
 467          */
 468         if ((dr6 & DR_STEP) && !user_mode(regs)) {
 469                 tsk->thread.debugreg6 &= ~DR_STEP;
 470                 set_tsk_thread_flag(tsk, TIF_SINGLESTEP);
 471                 regs->flags &= ~X86_EFLAGS_TF;
 472         }
 473         si_code = get_si_code(tsk->thread.debugreg6);
 474         if (tsk->thread.debugreg6 & (DR_STEP | DR_TRAP_BITS) || user_icebp)
 475                 send_sigtrap(tsk, regs, error_code, si_code);
 476         preempt_conditional_cli(regs);
 477         debug_stack_usage_dec();
 478
 479 exit:
 480         exception_exit(prev_state);
 481 }
 482
 483 /*
 484  * Note that we play around with the 'TS' bit in an attempt to get
 485  * the correct behaviour even in the presence of the asynchronous
 486  * IRQ13 behaviour
 487  */
 488 void math_error(struct pt_regs *regs, int error_code, int trapnr)
 489 {
 490         struct task_struct *task = current;
 491         siginfo_t info;
 492         unsigned short err;
 493         char *str = (trapnr == X86_TRAP_MF) ? "fpu exception" :
 494                                                 "simd exception";
 495
 496         if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, SIGFPE) == NOTIFY_STOP)
 497                 return;
 498         conditional_sti(regs);
 499
 500         if (!user_mode_vm(regs))
 501         {
 502                 if (!fixup_exception(regs)) {
 503                         task->thread.error_code = error_code;
 504                         task->thread.trap_nr = trapnr;
 505                         die(str, regs, error_code);
 506                 }
 507                 return;
 508         }
 509
 510         /*
 511          * Save the info for the exception handler and clear the error.
 512          */
 513         save_init_fpu(task);
 514         task->thread.trap_nr = trapnr;
 515         task->thread.error_code = error_code;
 516         info.si_signo = SIGFPE;
 517         info.si_errno = 0;
 518         info.si_addr = (void __user *)regs->ip;
 519         if (trapnr == X86_TRAP_MF) {
 520                 unsigned short cwd, swd;
 521                 /*
 522                  * (~cwd & swd) will mask out exceptions that are not set to unmasked
 523                  * status.  0x3f is the exception bits in these regs, 0x200 is the
 524                  * C1 reg you need in case of a stack fault, 0x040 is the stack
 525                  * fault bit.  We should only be taking one exception at a time,
 526                  * so if this combination doesn't produce any single exception,
 527                  * then we have a bad program that isn't synchronizing its FPU usage
 528                  * and it will suffer the consequences since we won't be able to
 529                  * fully reproduce the context of the exception
 530                  */
 531                 cwd = get_fpu_cwd(task);
 532                 swd = get_fpu_swd(task);
 533
 534                 err = swd & ~cwd;
 535         } else {
 536                 /*
 537                  * The SIMD FPU exceptions are handled a little differently, as there
 538                  * is only a single status/control register.  Thus, to determine which
 539                  * unmasked exception was caught we must mask the exception mask bits
 540                  * at 0x1f80, and then use these to mask the exception bits at 0x3f.
 541                  */
 542                 unsigned short mxcsr = get_fpu_mxcsr(task);
 543                 err = ~(mxcsr >> 7) & mxcsr;
 544         }
 545
 546         if (err & 0x001) {      /* Invalid op */
 547                 /*
 548                  * swd & 0x240 == 0x040: Stack Underflow
 549                  * swd & 0x240 == 0x240: Stack Overflow
 550                  * User must clear the SF bit (0x40) if set
 551                  */
 552                 info.si_code = FPE_FLTINV;
 553         } else if (err & 0x004) { /* Divide by Zero */
 554                 info.si_code = FPE_FLTDIV;
 555         } else if (err & 0x008) { /* Overflow */
 556                 info.si_code = FPE_FLTOVF;
 557         } else if (err & 0x012) { /* Denormal, Underflow */
 558                 info.si_code = FPE_FLTUND;
 559         } else if (err & 0x020) { /* Precision */
 560                 info.si_code = FPE_FLTRES;
 561         } else {
 562                 /*
 563                  * If we're using IRQ 13, or supposedly even some trap
 564                  * X86_TRAP_MF implementations, it's possible
 565                  * we get a spurious trap, which is not an error.
 566                  */
 567                 return;
 568         }
 569         force_sig_info(SIGFPE, &info, task);
 570 }
 571
 572 dotraplinkage void do_coprocessor_error(struct pt_regs *regs, long error_code)
 573 {
 574         enum ctx_state prev_state;
 575
 576         prev_state = exception_enter();
 577         math_error(regs, error_code, X86_TRAP_MF);
 578         exception_exit(prev_state);
 579 }
 580
 581 dotraplinkage void
 582 do_simd_coprocessor_error(struct pt_regs *regs, long error_code)
 583 {
 584         enum ctx_state prev_state;
 585
 586         prev_state = exception_enter();
 587         math_error(regs, error_code, X86_TRAP_XF);
 588         exception_exit(prev_state);
 589 }
 590
 591 dotraplinkage void
 592 do_spurious_interrupt_bug(struct pt_regs *regs, long error_code)
 593 {
 594         conditional_sti(regs);
 595 #if 0
 596         /* No need to warn about this any longer. */
 597         pr_info("Ignoring P6 Local APIC Spurious Interrupt Bug...\n");
 598 #endif
 599 }
 600
 601 asmlinkage void __attribute__((weak)) smp_thermal_interrupt(void)
 602 {
 603 }
 604
 605 asmlinkage void __attribute__((weak)) smp_threshold_interrupt(void)
 606 {
 607 }
 608
 609 /*
 610  * 'math_state_restore()' saves the current math information in the
 611  * old math state array, and gets the new ones from the current task
 612  *
 613  * Careful.. There are problems with IBM-designed IRQ13 behaviour.
 614  * Don't touch unless you *really* know how it works.
 615  *
 616  * Must be called with kernel preemption disabled (eg with local
 617  * local interrupts as in the case of do_device_not_available).
 618  */
 619 void math_state_restore(void)
 620 {
 621         struct task_struct *tsk = current;
 622
 623         if (!tsk_used_math(tsk)) {
 624                 local_irq_enable();
 625                 /*
 626                  * does a slab alloc which can sleep
 627                  */
 628                 if (init_fpu(tsk)) {
 629                         /*
 630                          * ran out of memory!
 631                          */
 632                         do_group_exit(SIGKILL);
 633                         return;
 634                 }
 635                 local_irq_disable();
 636         }
 637
 638         __thread_fpu_begin(tsk);
 639
 640         /*
 641          * Paranoid restore. send a SIGSEGV if we fail to restore the state.
 642          */
 643         if (unlikely(restore_fpu_checking(tsk))) {
 644                 drop_init_fpu(tsk);
 645                 force_sig(SIGSEGV, tsk);
 646                 return;
 647         }
 648
 649         tsk->fpu_counter++;
 650 }
 651 EXPORT_SYMBOL_GPL(math_state_restore);
 652
 653 dotraplinkage void __kprobes
 654 do_device_not_available(struct pt_regs *regs, long error_code)
 655 {
 656         enum ctx_state prev_state;
 657
 658         prev_state = exception_enter();
 659         BUG_ON(use_eager_fpu());
 660
 661 #ifdef CONFIG_MATH_EMULATION
 662         if (read_cr0() & X86_CR0_EM) {
 663                 struct math_emu_info info = { };
 664
 665                 conditional_sti(regs);
 666
 667                 info.regs = regs;
 668                 math_emulate(&info);
 669                 exception_exit(prev_state);
 670                 return;
 671         }
 672 #endif
 673         math_state_restore(); /* interrupts still off */
 674 #ifdef CONFIG_X86_32
 675         conditional_sti(regs);
 676 #endif
 677         exception_exit(prev_state);
 678 }
 679
 680 #ifdef CONFIG_X86_32
 681 dotraplinkage void do_iret_error(struct pt_regs *regs, long error_code)
 682 {
 683         siginfo_t info;
 684         enum ctx_state prev_state;
 685
 686         prev_state = exception_enter();
 687         local_irq_enable();
 688
 689         info.si_signo = SIGILL;
 690         info.si_errno = 0;
 691         info.si_code = ILL_BADSTK;
 692         info.si_addr = NULL;
 693         if (notify_die(DIE_TRAP, "iret exception", regs, error_code,
 694                         X86_TRAP_IRET, SIGILL) != NOTIFY_STOP) {
 695                 do_trap(X86_TRAP_IRET, SIGILL, "iret exception", regs, error_code,
 696                         &info);
 697         }
 698         exception_exit(prev_state);
 699 }
 700 #endif
 701
 702 /* Set of traps needed for early debugging. */
 703 void __init early_trap_init(void)
 704 {
 705         set_intr_gate_ist(X86_TRAP_DB, &debug, DEBUG_STACK);
 706         /* int3 can be called from all */
 707         set_system_intr_gate_ist(X86_TRAP_BP, &int3, DEBUG_STACK);
 708 #ifdef CONFIG_X86_32
 709         set_intr_gate(X86_TRAP_PF, &page_fault);
 710 #endif
 711         load_idt(&idt_descr);
 712 }
 713
 714 void __init early_trap_pf_init(void)
 715 {
 716 #ifdef CONFIG_X86_64
 717         set_intr_gate(X86_TRAP_PF, &page_fault);
 718 #endif
 719 }
 720
 721 void __init trap_init(void)
 722 {
 723         int i;
 724
 725 #ifdef CONFIG_EISA
 726         void __iomem *p = early_ioremap(0x0FFFD9, 4);
 727
 728         if (readl(p) == 'E' + ('I'<<8) + ('S'<<16) + ('A'<<24))
 729                 EISA_bus = 1;
 730         early_iounmap(p, 4);
 731 #endif
 732
 733         set_intr_gate(X86_TRAP_DE, &divide_error);
 734         set_intr_gate_ist(X86_TRAP_NMI, &nmi, NMI_STACK);
 735         /* int4 can be called from all */
 736         set_system_intr_gate(X86_TRAP_OF, &overflow);
 737         set_intr_gate(X86_TRAP_BR, &bounds);
 738         set_intr_gate(X86_TRAP_UD, &invalid_op);
 739         set_intr_gate(X86_TRAP_NM, &device_not_available);
 740 #ifdef CONFIG_X86_32
 741         set_task_gate(X86_TRAP_DF, GDT_ENTRY_DOUBLEFAULT_TSS);
 742 #else
 743         set_intr_gate_ist(X86_TRAP_DF, &double_fault, DOUBLEFAULT_STACK);
 744 #endif
 745         set_intr_gate(X86_TRAP_OLD_MF, &coprocessor_segment_overrun);
 746         set_intr_gate(X86_TRAP_TS, &invalid_TSS);
 747         set_intr_gate(X86_TRAP_NP, &segment_not_present);
 748         set_intr_gate_ist(X86_TRAP_SS, &stack_segment, STACKFAULT_STACK);
 749         set_intr_gate(X86_TRAP_GP, &general_protection);
 750         set_intr_gate(X86_TRAP_SPURIOUS, &spurious_interrupt_bug);
 751         set_intr_gate(X86_TRAP_MF, &coprocessor_error);
 752         set_intr_gate(X86_TRAP_AC, &alignment_check);
 753 #ifdef CONFIG_X86_MCE
 754         set_intr_gate_ist(X86_TRAP_MC, &machine_check, MCE_STACK);
 755 #endif
 756         set_intr_gate(X86_TRAP_XF, &simd_coprocessor_error);
 757
 758         /* Reserve all the builtin and the syscall vector: */
 759         for (i = 0; i < FIRST_EXTERNAL_VECTOR; i++)
 760                 set_bit(i, used_vectors);
 761
 762 #ifdef CONFIG_IA32_EMULATION
 763         set_system_intr_gate(IA32_SYSCALL_VECTOR, ia32_syscall);
 764         set_bit(IA32_SYSCALL_VECTOR, used_vectors);
 765 #endif
 766
 767 #ifdef CONFIG_X86_32
 768         set_system_trap_gate(SYSCALL_VECTOR, &system_call);
 769         set_bit(SYSCALL_VECTOR, used_vectors);
 770 #endif
 771
 772         /*
 773          * Set the IDT descriptor to a fixed read-only location, so that the
 774          * "sidt" instruction will not leak the location of the kernel, and
 775          * to defend the IDT against arbitrary memory write vulnerabilities.
 776          * It will be reloaded in cpu_init() */
 777         __set_fixmap(FIX_RO_IDT, __pa_symbol(idt_table), PAGE_KERNEL_RO);
 778         idt_descr.address = fix_to_virt(FIX_RO_IDT);
 779
 780         /*
 781          * Should be a barrier for any external CPU state:
 782          */
 783         cpu_init();
 784
 785         x86_init.irqs.trap_init();
 786
 787 #ifdef CONFIG_X86_64
 788         memcpy(&nmi_idt_table, &idt_table, IDT_ENTRIES * 16);
 789         set_nmi_gate(X86_TRAP_DB, &debug);
 790         set_nmi_gate(X86_TRAP_BP, &int3);
 791 #endif
 792 }