2 * Copyright (C) 1991, 1992 Linus Torvalds
3 * Copyright (C) 2000, 2001, 2002 Andi Kleen, SuSE Labs
5 * Pentium III FXSR, SSE support
6 * Gareth Hughes <gareth@valinux.com>, May 2000
10 * Handle hardware traps and faults.
13 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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>
36 #include <linux/smp.h>
40 #include <linux/ioport.h>
41 #include <linux/eisa.h>
44 #if defined(CONFIG_EDAC)
45 #include <linux/edac.h>
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>
57 #include <asm/fpu-internal.h>
59 #include <asm/fixmap.h>
60 #include <asm/mach_traps.h>
61 #include <asm/alternative.h>
64 #include <asm/x86_init.h>
65 #include <asm/pgalloc.h>
66 #include <asm/proto.h>
68 /* No need to be aligned, but done to keep all IDTs defined the same way. */
69 gate_desc debug_idt_table[NR_VECTORS] __page_aligned_bss;
71 #include <asm/processor-flags.h>
72 #include <asm/setup.h>
74 asmlinkage int system_call(void);
77 /* Must be page-aligned because the real IDT is used in a fixmap. */
78 gate_desc idt_table[NR_VECTORS] __page_aligned_bss;
80 DECLARE_BITMAP(used_vectors, NR_VECTORS);
81 EXPORT_SYMBOL_GPL(used_vectors);
83 static inline void conditional_sti(struct pt_regs *regs)
85 if (regs->flags & X86_EFLAGS_IF)
89 static inline void preempt_conditional_sti(struct pt_regs *regs)
92 if (regs->flags & X86_EFLAGS_IF)
96 static inline void conditional_cli(struct pt_regs *regs)
98 if (regs->flags & X86_EFLAGS_IF)
102 static inline void preempt_conditional_cli(struct pt_regs *regs)
104 if (regs->flags & X86_EFLAGS_IF)
110 do_trap_no_signal(struct task_struct *tsk, int trapnr, char *str,
111 struct pt_regs *regs, long error_code)
114 if (regs->flags & X86_VM_MASK) {
116 * Traps 0, 1, 3, 4, and 5 should be forwarded to vm86.
117 * On nmi (interrupt 2), do_trap should not be called.
119 if (trapnr < X86_TRAP_UD) {
120 if (!handle_vm86_trap((struct kernel_vm86_regs *) regs,
127 if (!user_mode(regs)) {
128 if (!fixup_exception(regs)) {
129 tsk->thread.error_code = error_code;
130 tsk->thread.trap_nr = trapnr;
131 die(str, regs, error_code);
139 static void __kprobes
140 do_trap(int trapnr, int signr, char *str, struct pt_regs *regs,
141 long error_code, siginfo_t *info)
143 struct task_struct *tsk = current;
146 if (!do_trap_no_signal(tsk, trapnr, str, regs, error_code))
149 * We want error_code and trap_nr set for userspace faults and
150 * kernelspace faults which result in die(), but not
151 * kernelspace faults which are fixed up. die() gives the
152 * process no chance to handle the signal and notice the
153 * kernel fault information, so that won't result in polluting
154 * the information about previously queued, but not yet
155 * delivered, faults. See also do_general_protection below.
157 tsk->thread.error_code = error_code;
158 tsk->thread.trap_nr = trapnr;
161 if (show_unhandled_signals && unhandled_signal(tsk, signr) &&
162 printk_ratelimit()) {
163 pr_info("%s[%d] trap %s ip:%lx sp:%lx error:%lx",
164 tsk->comm, tsk->pid, str,
165 regs->ip, regs->sp, error_code);
166 print_vma_addr(" in ", regs->ip);
172 force_sig_info(signr, info, tsk);
174 force_sig(signr, tsk);
177 #define DO_ERROR(trapnr, signr, str, name) \
178 dotraplinkage void do_##name(struct pt_regs *regs, long error_code) \
180 enum ctx_state prev_state; \
182 prev_state = exception_enter(); \
183 if (notify_die(DIE_TRAP, str, regs, error_code, \
184 trapnr, signr) == NOTIFY_STOP) { \
185 exception_exit(prev_state); \
188 conditional_sti(regs); \
189 do_trap(trapnr, signr, str, regs, error_code, NULL); \
190 exception_exit(prev_state); \
193 #define DO_ERROR_INFO(trapnr, signr, str, name, sicode, siaddr) \
194 dotraplinkage void do_##name(struct pt_regs *regs, long error_code) \
197 enum ctx_state prev_state; \
199 info.si_signo = signr; \
201 info.si_code = sicode; \
202 info.si_addr = (void __user *)siaddr; \
203 prev_state = exception_enter(); \
204 if (notify_die(DIE_TRAP, str, regs, error_code, \
205 trapnr, signr) == NOTIFY_STOP) { \
206 exception_exit(prev_state); \
209 conditional_sti(regs); \
210 do_trap(trapnr, signr, str, regs, error_code, &info); \
211 exception_exit(prev_state); \
214 DO_ERROR_INFO(X86_TRAP_DE, SIGFPE, "divide error", divide_error, FPE_INTDIV, regs->ip )
215 DO_ERROR (X86_TRAP_OF, SIGSEGV, "overflow", overflow )
216 DO_ERROR (X86_TRAP_BR, SIGSEGV, "bounds", bounds )
217 DO_ERROR_INFO(X86_TRAP_UD, SIGILL, "invalid opcode", invalid_op, ILL_ILLOPN, regs->ip )
218 DO_ERROR (X86_TRAP_OLD_MF, SIGFPE, "coprocessor segment overrun", coprocessor_segment_overrun )
219 DO_ERROR (X86_TRAP_TS, SIGSEGV, "invalid TSS", invalid_TSS )
220 DO_ERROR (X86_TRAP_NP, SIGBUS, "segment not present", segment_not_present )
221 DO_ERROR (X86_TRAP_SS, SIGBUS, "stack segment", stack_segment )
222 DO_ERROR_INFO(X86_TRAP_AC, SIGBUS, "alignment check", alignment_check, BUS_ADRALN, 0 )
225 /* Runs on IST stack */
226 dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code)
228 static const char str[] = "double fault";
229 struct task_struct *tsk = current;
231 #ifdef CONFIG_X86_ESPFIX64
232 extern unsigned char native_irq_return_iret[];
235 * If IRET takes a non-IST fault on the espfix64 stack, then we
236 * end up promoting it to a doublefault. In that case, modify
237 * the stack to make it look like we just entered the #GP
238 * handler from user space, similar to bad_iret.
240 if (((long)regs->sp >> PGDIR_SHIFT) == ESPFIX_PGD_ENTRY &&
241 regs->cs == __KERNEL_CS &&
242 regs->ip == (unsigned long)native_irq_return_iret)
244 struct pt_regs *normal_regs = task_pt_regs(current);
246 /* Fake a #GP(0) from userspace. */
247 memmove(&normal_regs->ip, (void *)regs->sp, 5*8);
248 normal_regs->orig_ax = 0; /* Missing (lost) #GP error code */
249 regs->ip = (unsigned long)general_protection;
250 regs->sp = (unsigned long)&normal_regs->orig_ax;
256 /* Return not checked because double check cannot be ignored */
257 notify_die(DIE_TRAP, str, regs, error_code, X86_TRAP_DF, SIGSEGV);
259 tsk->thread.error_code = error_code;
260 tsk->thread.trap_nr = X86_TRAP_DF;
262 #ifdef CONFIG_DOUBLEFAULT
263 df_debug(regs, error_code);
266 * This is always a kernel trap and never fixable (and thus must
270 die(str, regs, error_code);
274 dotraplinkage void __kprobes
275 do_general_protection(struct pt_regs *regs, long error_code)
277 struct task_struct *tsk;
278 enum ctx_state prev_state;
280 prev_state = exception_enter();
281 conditional_sti(regs);
284 if (regs->flags & X86_VM_MASK) {
286 handle_vm86_fault((struct kernel_vm86_regs *) regs, error_code);
292 if (!user_mode(regs)) {
293 if (fixup_exception(regs))
296 tsk->thread.error_code = error_code;
297 tsk->thread.trap_nr = X86_TRAP_GP;
298 if (notify_die(DIE_GPF, "general protection fault", regs, error_code,
299 X86_TRAP_GP, SIGSEGV) != NOTIFY_STOP)
300 die("general protection fault", regs, error_code);
304 tsk->thread.error_code = error_code;
305 tsk->thread.trap_nr = X86_TRAP_GP;
307 if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) &&
308 printk_ratelimit()) {
309 pr_info("%s[%d] general protection ip:%lx sp:%lx error:%lx",
310 tsk->comm, task_pid_nr(tsk),
311 regs->ip, regs->sp, error_code);
312 print_vma_addr(" in ", regs->ip);
316 force_sig(SIGSEGV, tsk);
318 exception_exit(prev_state);
321 /* May run on IST stack. */
322 dotraplinkage void __kprobes notrace do_int3(struct pt_regs *regs, long error_code)
324 enum ctx_state prev_state;
326 #ifdef CONFIG_DYNAMIC_FTRACE
328 * ftrace must be first, everything else may cause a recursive crash.
329 * See note by declaration of modifying_ftrace_code in ftrace.c
331 if (unlikely(atomic_read(&modifying_ftrace_code)) &&
332 ftrace_int3_handler(regs))
335 if (poke_int3_handler(regs))
338 prev_state = exception_enter();
339 #ifdef CONFIG_KGDB_LOW_LEVEL_TRAP
340 if (kgdb_ll_trap(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP,
341 SIGTRAP) == NOTIFY_STOP)
343 #endif /* CONFIG_KGDB_LOW_LEVEL_TRAP */
345 if (notify_die(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP,
346 SIGTRAP) == NOTIFY_STOP)
350 * Let others (NMI) know that the debug stack is in use
351 * as we may switch to the interrupt stack.
353 debug_stack_usage_inc();
354 preempt_conditional_sti(regs);
355 do_trap(X86_TRAP_BP, SIGTRAP, "int3", regs, error_code, NULL);
356 preempt_conditional_cli(regs);
357 debug_stack_usage_dec();
359 exception_exit(prev_state);
364 * Help handler running on IST stack to switch back to user stack
365 * for scheduling or signal handling. The actual stack switch is done in
368 asmlinkage __kprobes struct pt_regs *sync_regs(struct pt_regs *eregs)
370 struct pt_regs *regs = eregs;
371 /* Did already sync */
372 if (eregs == (struct pt_regs *)eregs->sp)
374 /* Exception from user space */
375 else if (user_mode(eregs))
376 regs = task_pt_regs(current);
378 * Exception from kernel and interrupts are enabled. Move to
379 * kernel process stack.
381 else if (eregs->flags & X86_EFLAGS_IF)
382 regs = (struct pt_regs *)(eregs->sp -= sizeof(struct pt_regs));
388 struct bad_iret_stack {
389 void *error_entry_ret;
394 struct bad_iret_stack *fixup_bad_iret(struct bad_iret_stack *s)
397 * This is called from entry_64.S early in handling a fault
398 * caused by a bad iret to user mode. To handle the fault
399 * correctly, we want move our stack frame to task_pt_regs
400 * and we want to pretend that the exception came from the
403 struct bad_iret_stack *new_stack =
404 container_of(task_pt_regs(current),
405 struct bad_iret_stack, regs);
407 /* Copy the IRET target to the new stack. */
408 memmove(&new_stack->regs.ip, (void *)s->regs.sp, 5*8);
410 /* Copy the remainder of the stack from the current stack. */
411 memmove(new_stack, s, offsetof(struct bad_iret_stack, regs.ip));
413 BUG_ON(!user_mode_vm(&new_stack->regs));
419 * Our handling of the processor debug registers is non-trivial.
420 * We do not clear them on entry and exit from the kernel. Therefore
421 * it is possible to get a watchpoint trap here from inside the kernel.
422 * However, the code in ./ptrace.c has ensured that the user can
423 * only set watchpoints on userspace addresses. Therefore the in-kernel
424 * watchpoint trap can only occur in code which is reading/writing
425 * from user space. Such code must not hold kernel locks (since it
426 * can equally take a page fault), therefore it is safe to call
427 * force_sig_info even though that claims and releases locks.
429 * Code in ./signal.c ensures that the debug control register
430 * is restored before we deliver any signal, and therefore that
431 * user code runs with the correct debug control register even though
434 * Being careful here means that we don't have to be as careful in a
435 * lot of more complicated places (task switching can be a bit lazy
436 * about restoring all the debug state, and ptrace doesn't have to
437 * find every occurrence of the TF bit that could be saved away even
440 * May run on IST stack.
442 dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code)
444 struct task_struct *tsk = current;
445 enum ctx_state prev_state;
450 prev_state = exception_enter();
452 get_debugreg(dr6, 6);
454 /* Filter out all the reserved bits which are preset to 1 */
455 dr6 &= ~DR6_RESERVED;
458 * If dr6 has no reason to give us about the origin of this trap,
459 * then it's very likely the result of an icebp/int01 trap.
460 * User wants a sigtrap for that.
462 if (!dr6 && user_mode(regs))
465 /* Catch kmemcheck conditions first of all! */
466 if ((dr6 & DR_STEP) && kmemcheck_trap(regs))
469 /* DR6 may or may not be cleared by the CPU */
473 * The processor cleared BTF, so don't mark that we need it set.
475 clear_tsk_thread_flag(tsk, TIF_BLOCKSTEP);
477 /* Store the virtualized DR6 value */
478 tsk->thread.debugreg6 = dr6;
480 if (notify_die(DIE_DEBUG, "debug", regs, (long)&dr6, error_code,
481 SIGTRAP) == NOTIFY_STOP)
485 * Let others (NMI) know that the debug stack is in use
486 * as we may switch to the interrupt stack.
488 debug_stack_usage_inc();
490 /* It's safe to allow irq's after DR6 has been saved */
491 preempt_conditional_sti(regs);
493 if (regs->flags & X86_VM_MASK) {
494 handle_vm86_trap((struct kernel_vm86_regs *) regs, error_code,
496 preempt_conditional_cli(regs);
497 debug_stack_usage_dec();
502 * Single-stepping through system calls: ignore any exceptions in
503 * kernel space, but re-enable TF when returning to user mode.
505 * We already checked v86 mode above, so we can check for kernel mode
506 * by just checking the CPL of CS.
508 if ((dr6 & DR_STEP) && !user_mode(regs)) {
509 tsk->thread.debugreg6 &= ~DR_STEP;
510 set_tsk_thread_flag(tsk, TIF_SINGLESTEP);
511 regs->flags &= ~X86_EFLAGS_TF;
513 si_code = get_si_code(tsk->thread.debugreg6);
514 if (tsk->thread.debugreg6 & (DR_STEP | DR_TRAP_BITS) || user_icebp)
515 send_sigtrap(tsk, regs, error_code, si_code);
516 preempt_conditional_cli(regs);
517 debug_stack_usage_dec();
520 exception_exit(prev_state);
524 * Note that we play around with the 'TS' bit in an attempt to get
525 * the correct behaviour even in the presence of the asynchronous
528 void math_error(struct pt_regs *regs, int error_code, int trapnr)
530 struct task_struct *task = current;
533 char *str = (trapnr == X86_TRAP_MF) ? "fpu exception" :
536 if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, SIGFPE) == NOTIFY_STOP)
538 conditional_sti(regs);
540 if (!user_mode_vm(regs))
542 if (!fixup_exception(regs)) {
543 task->thread.error_code = error_code;
544 task->thread.trap_nr = trapnr;
545 die(str, regs, error_code);
551 * Save the info for the exception handler and clear the error.
554 task->thread.trap_nr = trapnr;
555 task->thread.error_code = error_code;
556 info.si_signo = SIGFPE;
558 info.si_addr = (void __user *)regs->ip;
559 if (trapnr == X86_TRAP_MF) {
560 unsigned short cwd, swd;
562 * (~cwd & swd) will mask out exceptions that are not set to unmasked
563 * status. 0x3f is the exception bits in these regs, 0x200 is the
564 * C1 reg you need in case of a stack fault, 0x040 is the stack
565 * fault bit. We should only be taking one exception at a time,
566 * so if this combination doesn't produce any single exception,
567 * then we have a bad program that isn't synchronizing its FPU usage
568 * and it will suffer the consequences since we won't be able to
569 * fully reproduce the context of the exception
571 cwd = get_fpu_cwd(task);
572 swd = get_fpu_swd(task);
577 * The SIMD FPU exceptions are handled a little differently, as there
578 * is only a single status/control register. Thus, to determine which
579 * unmasked exception was caught we must mask the exception mask bits
580 * at 0x1f80, and then use these to mask the exception bits at 0x3f.
582 unsigned short mxcsr = get_fpu_mxcsr(task);
583 err = ~(mxcsr >> 7) & mxcsr;
586 if (err & 0x001) { /* Invalid op */
588 * swd & 0x240 == 0x040: Stack Underflow
589 * swd & 0x240 == 0x240: Stack Overflow
590 * User must clear the SF bit (0x40) if set
592 info.si_code = FPE_FLTINV;
593 } else if (err & 0x004) { /* Divide by Zero */
594 info.si_code = FPE_FLTDIV;
595 } else if (err & 0x008) { /* Overflow */
596 info.si_code = FPE_FLTOVF;
597 } else if (err & 0x012) { /* Denormal, Underflow */
598 info.si_code = FPE_FLTUND;
599 } else if (err & 0x020) { /* Precision */
600 info.si_code = FPE_FLTRES;
603 * If we're using IRQ 13, or supposedly even some trap
604 * X86_TRAP_MF implementations, it's possible
605 * we get a spurious trap, which is not an error.
609 force_sig_info(SIGFPE, &info, task);
612 dotraplinkage void do_coprocessor_error(struct pt_regs *regs, long error_code)
614 enum ctx_state prev_state;
616 prev_state = exception_enter();
617 math_error(regs, error_code, X86_TRAP_MF);
618 exception_exit(prev_state);
622 do_simd_coprocessor_error(struct pt_regs *regs, long error_code)
624 enum ctx_state prev_state;
626 prev_state = exception_enter();
627 math_error(regs, error_code, X86_TRAP_XF);
628 exception_exit(prev_state);
632 do_spurious_interrupt_bug(struct pt_regs *regs, long error_code)
634 conditional_sti(regs);
636 /* No need to warn about this any longer. */
637 pr_info("Ignoring P6 Local APIC Spurious Interrupt Bug...\n");
641 asmlinkage void __attribute__((weak)) smp_thermal_interrupt(void)
645 asmlinkage void __attribute__((weak)) smp_threshold_interrupt(void)
650 * 'math_state_restore()' saves the current math information in the
651 * old math state array, and gets the new ones from the current task
653 * Careful.. There are problems with IBM-designed IRQ13 behaviour.
654 * Don't touch unless you *really* know how it works.
656 * Must be called with kernel preemption disabled (eg with local
657 * local interrupts as in the case of do_device_not_available).
659 void math_state_restore(void)
661 struct task_struct *tsk = current;
663 if (!tsk_used_math(tsk)) {
666 * does a slab alloc which can sleep
672 do_group_exit(SIGKILL);
678 __thread_fpu_begin(tsk);
681 * Paranoid restore. send a SIGSEGV if we fail to restore the state.
683 if (unlikely(restore_fpu_checking(tsk))) {
685 force_sig(SIGSEGV, tsk);
689 tsk->thread.fpu_counter++;
691 EXPORT_SYMBOL_GPL(math_state_restore);
693 dotraplinkage void __kprobes
694 do_device_not_available(struct pt_regs *regs, long error_code)
696 enum ctx_state prev_state;
698 prev_state = exception_enter();
699 BUG_ON(use_eager_fpu());
701 #ifdef CONFIG_MATH_EMULATION
702 if (read_cr0() & X86_CR0_EM) {
703 struct math_emu_info info = { };
705 conditional_sti(regs);
709 exception_exit(prev_state);
713 math_state_restore(); /* interrupts still off */
715 conditional_sti(regs);
717 exception_exit(prev_state);
721 dotraplinkage void do_iret_error(struct pt_regs *regs, long error_code)
724 enum ctx_state prev_state;
726 prev_state = exception_enter();
729 info.si_signo = SIGILL;
731 info.si_code = ILL_BADSTK;
733 if (notify_die(DIE_TRAP, "iret exception", regs, error_code,
734 X86_TRAP_IRET, SIGILL) != NOTIFY_STOP) {
735 do_trap(X86_TRAP_IRET, SIGILL, "iret exception", regs, error_code,
738 exception_exit(prev_state);
742 /* Set of traps needed for early debugging. */
743 void __init early_trap_init(void)
745 set_intr_gate_ist(X86_TRAP_DB, &debug, DEBUG_STACK);
746 /* int3 can be called from all */
747 set_system_intr_gate_ist(X86_TRAP_BP, &int3, DEBUG_STACK);
749 set_intr_gate(X86_TRAP_PF, page_fault);
751 load_idt(&idt_descr);
754 void __init early_trap_pf_init(void)
757 set_intr_gate(X86_TRAP_PF, page_fault);
761 void __init trap_init(void)
766 void __iomem *p = early_ioremap(0x0FFFD9, 4);
768 if (readl(p) == 'E' + ('I'<<8) + ('S'<<16) + ('A'<<24))
773 set_intr_gate(X86_TRAP_DE, divide_error);
774 set_intr_gate_ist(X86_TRAP_NMI, &nmi, NMI_STACK);
775 /* int4 can be called from all */
776 set_system_intr_gate(X86_TRAP_OF, &overflow);
777 set_intr_gate(X86_TRAP_BR, bounds);
778 set_intr_gate(X86_TRAP_UD, invalid_op);
779 set_intr_gate(X86_TRAP_NM, device_not_available);
781 set_task_gate(X86_TRAP_DF, GDT_ENTRY_DOUBLEFAULT_TSS);
783 set_intr_gate_ist(X86_TRAP_DF, &double_fault, DOUBLEFAULT_STACK);
785 set_intr_gate(X86_TRAP_OLD_MF, coprocessor_segment_overrun);
786 set_intr_gate(X86_TRAP_TS, invalid_TSS);
787 set_intr_gate(X86_TRAP_NP, segment_not_present);
788 set_intr_gate(X86_TRAP_SS, stack_segment);
789 set_intr_gate(X86_TRAP_GP, general_protection);
790 set_intr_gate(X86_TRAP_SPURIOUS, spurious_interrupt_bug);
791 set_intr_gate(X86_TRAP_MF, coprocessor_error);
792 set_intr_gate(X86_TRAP_AC, alignment_check);
793 #ifdef CONFIG_X86_MCE
794 set_intr_gate_ist(X86_TRAP_MC, &machine_check, MCE_STACK);
796 set_intr_gate(X86_TRAP_XF, simd_coprocessor_error);
798 /* Reserve all the builtin and the syscall vector: */
799 for (i = 0; i < FIRST_EXTERNAL_VECTOR; i++)
800 set_bit(i, used_vectors);
802 #ifdef CONFIG_IA32_EMULATION
803 set_system_intr_gate(IA32_SYSCALL_VECTOR, ia32_syscall);
804 set_bit(IA32_SYSCALL_VECTOR, used_vectors);
808 set_system_trap_gate(SYSCALL_VECTOR, &system_call);
809 set_bit(SYSCALL_VECTOR, used_vectors);
813 * Set the IDT descriptor to a fixed read-only location, so that the
814 * "sidt" instruction will not leak the location of the kernel, and
815 * to defend the IDT against arbitrary memory write vulnerabilities.
816 * It will be reloaded in cpu_init() */
817 __set_fixmap(FIX_RO_IDT, __pa_symbol(idt_table), PAGE_KERNEL_RO);
818 idt_descr.address = fix_to_virt(FIX_RO_IDT);
821 * Should be a barrier for any external CPU state:
825 x86_init.irqs.trap_init();
828 memcpy(&debug_idt_table, &idt_table, IDT_ENTRIES * 16);
829 set_nmi_gate(X86_TRAP_DB, &debug);
830 set_nmi_gate(X86_TRAP_BP, &int3);