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/export.h>
25 #include <linux/ptrace.h>
26 #include <linux/uprobes.h>
27 #include <linux/string.h>
28 #include <linux/delay.h>
29 #include <linux/errno.h>
30 #include <linux/kexec.h>
31 #include <linux/sched.h>
32 #include <linux/sched/task_stack.h>
33 #include <linux/timer.h>
34 #include <linux/init.h>
35 #include <linux/bug.h>
36 #include <linux/nmi.h>
38 #include <linux/smp.h>
42 #include <linux/ioport.h>
43 #include <linux/eisa.h>
46 #if defined(CONFIG_EDAC)
47 #include <linux/edac.h>
50 #include <asm/kmemcheck.h>
51 #include <asm/stacktrace.h>
52 #include <asm/processor.h>
53 #include <asm/debugreg.h>
54 #include <linux/atomic.h>
55 #include <asm/text-patching.h>
56 #include <asm/ftrace.h>
57 #include <asm/traps.h>
59 #include <asm/fpu/internal.h>
61 #include <asm/fixmap.h>
62 #include <asm/mach_traps.h>
63 #include <asm/alternative.h>
64 #include <asm/fpu/xstate.h>
65 #include <asm/trace/mpx.h>
70 #include <asm/x86_init.h>
71 #include <asm/pgalloc.h>
72 #include <asm/proto.h>
74 /* No need to be aligned, but done to keep all IDTs defined the same way. */
75 gate_desc debug_idt_table[NR_VECTORS] __page_aligned_bss;
77 #include <asm/processor-flags.h>
78 #include <asm/setup.h>
79 #include <asm/proto.h>
82 /* Must be page-aligned because the real IDT is used in a fixmap. */
83 gate_desc idt_table[NR_VECTORS] __page_aligned_bss;
85 DECLARE_BITMAP(used_vectors, NR_VECTORS);
86 EXPORT_SYMBOL_GPL(used_vectors);
88 static inline void cond_local_irq_enable(struct pt_regs *regs)
90 if (regs->flags & X86_EFLAGS_IF)
94 static inline void cond_local_irq_disable(struct pt_regs *regs)
96 if (regs->flags & X86_EFLAGS_IF)
101 * In IST context, we explicitly disable preemption. This serves two
102 * purposes: it makes it much less likely that we would accidentally
103 * schedule in IST context and it will force a warning if we somehow
104 * manage to schedule by accident.
106 void ist_enter(struct pt_regs *regs)
108 if (user_mode(regs)) {
109 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
112 * We might have interrupted pretty much anything. In
113 * fact, if we're a machine check, we can even interrupt
114 * NMI processing. We don't want in_nmi() to return true,
115 * but we need to notify RCU.
122 /* This code is a bit fragile. Test it. */
123 RCU_LOCKDEP_WARN(!rcu_is_watching(), "ist_enter didn't work");
126 void ist_exit(struct pt_regs *regs)
128 preempt_enable_no_resched();
130 if (!user_mode(regs))
135 * ist_begin_non_atomic() - begin a non-atomic section in an IST exception
136 * @regs: regs passed to the IST exception handler
138 * IST exception handlers normally cannot schedule. As a special
139 * exception, if the exception interrupted userspace code (i.e.
140 * user_mode(regs) would return true) and the exception was not
141 * a double fault, it can be safe to schedule. ist_begin_non_atomic()
142 * begins a non-atomic section within an ist_enter()/ist_exit() region.
143 * Callers are responsible for enabling interrupts themselves inside
144 * the non-atomic section, and callers must call ist_end_non_atomic()
147 void ist_begin_non_atomic(struct pt_regs *regs)
149 BUG_ON(!user_mode(regs));
152 * Sanity check: we need to be on the normal thread stack. This
153 * will catch asm bugs and any attempt to use ist_preempt_enable
156 BUG_ON((unsigned long)(current_top_of_stack() -
157 current_stack_pointer()) >= THREAD_SIZE);
159 preempt_enable_no_resched();
163 * ist_end_non_atomic() - begin a non-atomic section in an IST exception
165 * Ends a non-atomic section started with ist_begin_non_atomic().
167 void ist_end_non_atomic(void)
172 static nokprobe_inline int
173 do_trap_no_signal(struct task_struct *tsk, int trapnr, char *str,
174 struct pt_regs *regs, long error_code)
176 if (v8086_mode(regs)) {
178 * Traps 0, 1, 3, 4, and 5 should be forwarded to vm86.
179 * On nmi (interrupt 2), do_trap should not be called.
181 if (trapnr < X86_TRAP_UD) {
182 if (!handle_vm86_trap((struct kernel_vm86_regs *) regs,
189 if (!user_mode(regs)) {
190 if (!fixup_exception(regs, trapnr)) {
191 tsk->thread.error_code = error_code;
192 tsk->thread.trap_nr = trapnr;
193 die(str, regs, error_code);
201 static siginfo_t *fill_trap_info(struct pt_regs *regs, int signr, int trapnr,
204 unsigned long siaddr;
209 return SEND_SIG_PRIV;
213 siaddr = uprobe_get_trap_addr(regs);
217 siaddr = uprobe_get_trap_addr(regs);
225 info->si_signo = signr;
227 info->si_code = sicode;
228 info->si_addr = (void __user *)siaddr;
233 do_trap(int trapnr, int signr, char *str, struct pt_regs *regs,
234 long error_code, siginfo_t *info)
236 struct task_struct *tsk = current;
239 if (!do_trap_no_signal(tsk, trapnr, str, regs, error_code))
242 * We want error_code and trap_nr set for userspace faults and
243 * kernelspace faults which result in die(), but not
244 * kernelspace faults which are fixed up. die() gives the
245 * process no chance to handle the signal and notice the
246 * kernel fault information, so that won't result in polluting
247 * the information about previously queued, but not yet
248 * delivered, faults. See also do_general_protection below.
250 tsk->thread.error_code = error_code;
251 tsk->thread.trap_nr = trapnr;
253 if (show_unhandled_signals && unhandled_signal(tsk, signr) &&
254 printk_ratelimit()) {
255 pr_info("%s[%d] trap %s ip:%lx sp:%lx error:%lx",
256 tsk->comm, tsk->pid, str,
257 regs->ip, regs->sp, error_code);
258 print_vma_addr(KERN_CONT " in ", regs->ip);
262 force_sig_info(signr, info ?: SEND_SIG_PRIV, tsk);
264 NOKPROBE_SYMBOL(do_trap);
266 static void do_error_trap(struct pt_regs *regs, long error_code, char *str,
267 unsigned long trapnr, int signr)
271 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
273 if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) !=
275 cond_local_irq_enable(regs);
276 do_trap(trapnr, signr, str, regs, error_code,
277 fill_trap_info(regs, signr, trapnr, &info));
281 #define DO_ERROR(trapnr, signr, str, name) \
282 dotraplinkage void do_##name(struct pt_regs *regs, long error_code) \
284 do_error_trap(regs, error_code, str, trapnr, signr); \
287 DO_ERROR(X86_TRAP_DE, SIGFPE, "divide error", divide_error)
288 DO_ERROR(X86_TRAP_OF, SIGSEGV, "overflow", overflow)
289 DO_ERROR(X86_TRAP_UD, SIGILL, "invalid opcode", invalid_op)
290 DO_ERROR(X86_TRAP_OLD_MF, SIGFPE, "coprocessor segment overrun",coprocessor_segment_overrun)
291 DO_ERROR(X86_TRAP_TS, SIGSEGV, "invalid TSS", invalid_TSS)
292 DO_ERROR(X86_TRAP_NP, SIGBUS, "segment not present", segment_not_present)
293 DO_ERROR(X86_TRAP_SS, SIGBUS, "stack segment", stack_segment)
294 DO_ERROR(X86_TRAP_AC, SIGBUS, "alignment check", alignment_check)
296 #ifdef CONFIG_VMAP_STACK
297 __visible void __noreturn handle_stack_overflow(const char *message,
298 struct pt_regs *regs,
299 unsigned long fault_address)
301 printk(KERN_EMERG "BUG: stack guard page was hit at %p (stack is %p..%p)\n",
302 (void *)fault_address, current->stack,
303 (char *)current->stack + THREAD_SIZE - 1);
304 die(message, regs, 0);
306 /* Be absolutely certain we don't return. */
312 /* Runs on IST stack */
313 dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code)
315 static const char str[] = "double fault";
316 struct task_struct *tsk = current;
317 #ifdef CONFIG_VMAP_STACK
321 #ifdef CONFIG_X86_ESPFIX64
322 extern unsigned char native_irq_return_iret[];
325 * If IRET takes a non-IST fault on the espfix64 stack, then we
326 * end up promoting it to a doublefault. In that case, modify
327 * the stack to make it look like we just entered the #GP
328 * handler from user space, similar to bad_iret.
330 * No need for ist_enter here because we don't use RCU.
332 if (((long)regs->sp >> PGDIR_SHIFT) == ESPFIX_PGD_ENTRY &&
333 regs->cs == __KERNEL_CS &&
334 regs->ip == (unsigned long)native_irq_return_iret)
336 struct pt_regs *normal_regs = task_pt_regs(current);
338 /* Fake a #GP(0) from userspace. */
339 memmove(&normal_regs->ip, (void *)regs->sp, 5*8);
340 normal_regs->orig_ax = 0; /* Missing (lost) #GP error code */
341 regs->ip = (unsigned long)general_protection;
342 regs->sp = (unsigned long)&normal_regs->orig_ax;
349 notify_die(DIE_TRAP, str, regs, error_code, X86_TRAP_DF, SIGSEGV);
351 tsk->thread.error_code = error_code;
352 tsk->thread.trap_nr = X86_TRAP_DF;
354 #ifdef CONFIG_VMAP_STACK
356 * If we overflow the stack into a guard page, the CPU will fail
357 * to deliver #PF and will send #DF instead. Similarly, if we
358 * take any non-IST exception while too close to the bottom of
359 * the stack, the processor will get a page fault while
360 * delivering the exception and will generate a double fault.
362 * According to the SDM (footnote in 6.15 under "Interrupt 14 -
363 * Page-Fault Exception (#PF):
365 * Processors update CR2 whenever a page fault is detected. If a
366 * second page fault occurs while an earlier page fault is being
367 * deliv- ered, the faulting linear address of the second fault will
368 * overwrite the contents of CR2 (replacing the previous
369 * address). These updates to CR2 occur even if the page fault
370 * results in a double fault or occurs during the delivery of a
373 * The logic below has a small possibility of incorrectly diagnosing
374 * some errors as stack overflows. For example, if the IDT or GDT
375 * gets corrupted such that #GP delivery fails due to a bad descriptor
376 * causing #GP and we hit this condition while CR2 coincidentally
377 * points to the stack guard page, we'll think we overflowed the
378 * stack. Given that we're going to panic one way or another
379 * if this happens, this isn't necessarily worth fixing.
381 * If necessary, we could improve the test by only diagnosing
382 * a stack overflow if the saved RSP points within 47 bytes of
383 * the bottom of the stack: if RSP == tsk_stack + 48 and we
384 * take an exception, the stack is already aligned and there
385 * will be enough room SS, RSP, RFLAGS, CS, RIP, and a
386 * possible error code, so a stack overflow would *not* double
387 * fault. With any less space left, exception delivery could
388 * fail, and, as a practical matter, we've overflowed the
389 * stack even if the actual trigger for the double fault was
393 if ((unsigned long)task_stack_page(tsk) - 1 - cr2 < PAGE_SIZE)
394 handle_stack_overflow("kernel stack overflow (double-fault)", regs, cr2);
397 #ifdef CONFIG_DOUBLEFAULT
398 df_debug(regs, error_code);
401 * This is always a kernel trap and never fixable (and thus must
405 die(str, regs, error_code);
409 dotraplinkage void do_bounds(struct pt_regs *regs, long error_code)
411 const struct mpx_bndcsr *bndcsr;
414 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
415 if (notify_die(DIE_TRAP, "bounds", regs, error_code,
416 X86_TRAP_BR, SIGSEGV) == NOTIFY_STOP)
418 cond_local_irq_enable(regs);
420 if (!user_mode(regs))
421 die("bounds", regs, error_code);
423 if (!cpu_feature_enabled(X86_FEATURE_MPX)) {
424 /* The exception is not from Intel MPX */
429 * We need to look at BNDSTATUS to resolve this exception.
430 * A NULL here might mean that it is in its 'init state',
431 * which is all zeros which indicates MPX was not
432 * responsible for the exception.
434 bndcsr = get_xsave_field_ptr(XFEATURE_MASK_BNDCSR);
438 trace_bounds_exception_mpx(bndcsr);
440 * The error code field of the BNDSTATUS register communicates status
441 * information of a bound range exception #BR or operation involving
444 switch (bndcsr->bndstatus & MPX_BNDSTA_ERROR_CODE) {
445 case 2: /* Bound directory has invalid entry. */
446 if (mpx_handle_bd_fault())
448 break; /* Success, it was handled */
449 case 1: /* Bound violation. */
450 info = mpx_generate_siginfo(regs);
453 * We failed to decode the MPX instruction. Act as if
454 * the exception was not caused by MPX.
459 * Success, we decoded the instruction and retrieved
460 * an 'info' containing the address being accessed
461 * which caused the exception. This information
462 * allows and application to possibly handle the
463 * #BR exception itself.
465 do_trap(X86_TRAP_BR, SIGSEGV, "bounds", regs, error_code, info);
468 case 0: /* No exception caused by Intel MPX operations. */
471 die("bounds", regs, error_code);
478 * This path out is for all the cases where we could not
479 * handle the exception in some way (like allocating a
480 * table or telling userspace about it. We will also end
481 * up here if the kernel has MPX turned off at compile
484 do_trap(X86_TRAP_BR, SIGSEGV, "bounds", regs, error_code, NULL);
488 do_general_protection(struct pt_regs *regs, long error_code)
490 struct task_struct *tsk;
492 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
493 cond_local_irq_enable(regs);
495 if (v8086_mode(regs)) {
497 handle_vm86_fault((struct kernel_vm86_regs *) regs, error_code);
502 if (!user_mode(regs)) {
503 if (fixup_exception(regs, X86_TRAP_GP))
506 tsk->thread.error_code = error_code;
507 tsk->thread.trap_nr = X86_TRAP_GP;
508 if (notify_die(DIE_GPF, "general protection fault", regs, error_code,
509 X86_TRAP_GP, SIGSEGV) != NOTIFY_STOP)
510 die("general protection fault", regs, error_code);
514 tsk->thread.error_code = error_code;
515 tsk->thread.trap_nr = X86_TRAP_GP;
517 if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) &&
518 printk_ratelimit()) {
519 pr_info("%s[%d] general protection ip:%lx sp:%lx error:%lx",
520 tsk->comm, task_pid_nr(tsk),
521 regs->ip, regs->sp, error_code);
522 print_vma_addr(KERN_CONT " in ", regs->ip);
526 force_sig_info(SIGSEGV, SEND_SIG_PRIV, tsk);
528 NOKPROBE_SYMBOL(do_general_protection);
530 /* May run on IST stack. */
531 dotraplinkage void notrace do_int3(struct pt_regs *regs, long error_code)
533 #ifdef CONFIG_DYNAMIC_FTRACE
535 * ftrace must be first, everything else may cause a recursive crash.
536 * See note by declaration of modifying_ftrace_code in ftrace.c
538 if (unlikely(atomic_read(&modifying_ftrace_code)) &&
539 ftrace_int3_handler(regs))
542 if (poke_int3_handler(regs))
546 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
547 #ifdef CONFIG_KGDB_LOW_LEVEL_TRAP
548 if (kgdb_ll_trap(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP,
549 SIGTRAP) == NOTIFY_STOP)
551 #endif /* CONFIG_KGDB_LOW_LEVEL_TRAP */
553 #ifdef CONFIG_KPROBES
554 if (kprobe_int3_handler(regs))
558 if (notify_die(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP,
559 SIGTRAP) == NOTIFY_STOP)
563 * Let others (NMI) know that the debug stack is in use
564 * as we may switch to the interrupt stack.
566 debug_stack_usage_inc();
567 cond_local_irq_enable(regs);
568 do_trap(X86_TRAP_BP, SIGTRAP, "int3", regs, error_code, NULL);
569 cond_local_irq_disable(regs);
570 debug_stack_usage_dec();
574 NOKPROBE_SYMBOL(do_int3);
578 * Help handler running on IST stack to switch off the IST stack if the
579 * interrupted code was in user mode. The actual stack switch is done in
582 asmlinkage __visible notrace struct pt_regs *sync_regs(struct pt_regs *eregs)
584 struct pt_regs *regs = task_pt_regs(current);
588 NOKPROBE_SYMBOL(sync_regs);
590 struct bad_iret_stack {
591 void *error_entry_ret;
595 asmlinkage __visible notrace
596 struct bad_iret_stack *fixup_bad_iret(struct bad_iret_stack *s)
599 * This is called from entry_64.S early in handling a fault
600 * caused by a bad iret to user mode. To handle the fault
601 * correctly, we want move our stack frame to task_pt_regs
602 * and we want to pretend that the exception came from the
605 struct bad_iret_stack *new_stack =
606 container_of(task_pt_regs(current),
607 struct bad_iret_stack, regs);
609 /* Copy the IRET target to the new stack. */
610 memmove(&new_stack->regs.ip, (void *)s->regs.sp, 5*8);
612 /* Copy the remainder of the stack from the current stack. */
613 memmove(new_stack, s, offsetof(struct bad_iret_stack, regs.ip));
615 BUG_ON(!user_mode(&new_stack->regs));
618 NOKPROBE_SYMBOL(fixup_bad_iret);
621 static bool is_sysenter_singlestep(struct pt_regs *regs)
624 * We don't try for precision here. If we're anywhere in the region of
625 * code that can be single-stepped in the SYSENTER entry path, then
626 * assume that this is a useless single-step trap due to SYSENTER
627 * being invoked with TF set. (We don't know in advance exactly
628 * which instructions will be hit because BTF could plausibly
632 return (regs->ip - (unsigned long)__begin_SYSENTER_singlestep_region) <
633 (unsigned long)__end_SYSENTER_singlestep_region -
634 (unsigned long)__begin_SYSENTER_singlestep_region;
635 #elif defined(CONFIG_IA32_EMULATION)
636 return (regs->ip - (unsigned long)entry_SYSENTER_compat) <
637 (unsigned long)__end_entry_SYSENTER_compat -
638 (unsigned long)entry_SYSENTER_compat;
645 * Our handling of the processor debug registers is non-trivial.
646 * We do not clear them on entry and exit from the kernel. Therefore
647 * it is possible to get a watchpoint trap here from inside the kernel.
648 * However, the code in ./ptrace.c has ensured that the user can
649 * only set watchpoints on userspace addresses. Therefore the in-kernel
650 * watchpoint trap can only occur in code which is reading/writing
651 * from user space. Such code must not hold kernel locks (since it
652 * can equally take a page fault), therefore it is safe to call
653 * force_sig_info even though that claims and releases locks.
655 * Code in ./signal.c ensures that the debug control register
656 * is restored before we deliver any signal, and therefore that
657 * user code runs with the correct debug control register even though
660 * Being careful here means that we don't have to be as careful in a
661 * lot of more complicated places (task switching can be a bit lazy
662 * about restoring all the debug state, and ptrace doesn't have to
663 * find every occurrence of the TF bit that could be saved away even
666 * May run on IST stack.
668 dotraplinkage void do_debug(struct pt_regs *regs, long error_code)
670 struct task_struct *tsk = current;
677 get_debugreg(dr6, 6);
679 * The Intel SDM says:
681 * Certain debug exceptions may clear bits 0-3. The remaining
682 * contents of the DR6 register are never cleared by the
683 * processor. To avoid confusion in identifying debug
684 * exceptions, debug handlers should clear the register before
685 * returning to the interrupted task.
687 * Keep it simple: clear DR6 immediately.
691 /* Filter out all the reserved bits which are preset to 1 */
692 dr6 &= ~DR6_RESERVED;
695 * The SDM says "The processor clears the BTF flag when it
696 * generates a debug exception." Clear TIF_BLOCKSTEP to keep
697 * TIF_BLOCKSTEP in sync with the hardware BTF flag.
699 clear_tsk_thread_flag(tsk, TIF_BLOCKSTEP);
701 if (unlikely(!user_mode(regs) && (dr6 & DR_STEP) &&
702 is_sysenter_singlestep(regs))) {
707 * else we might have gotten a single-step trap and hit a
708 * watchpoint at the same time, in which case we should fall
709 * through and handle the watchpoint.
714 * If dr6 has no reason to give us about the origin of this trap,
715 * then it's very likely the result of an icebp/int01 trap.
716 * User wants a sigtrap for that.
718 if (!dr6 && user_mode(regs))
721 /* Catch kmemcheck conditions! */
722 if ((dr6 & DR_STEP) && kmemcheck_trap(regs))
725 /* Store the virtualized DR6 value */
726 tsk->thread.debugreg6 = dr6;
728 #ifdef CONFIG_KPROBES
729 if (kprobe_debug_handler(regs))
733 if (notify_die(DIE_DEBUG, "debug", regs, (long)&dr6, error_code,
734 SIGTRAP) == NOTIFY_STOP)
738 * Let others (NMI) know that the debug stack is in use
739 * as we may switch to the interrupt stack.
741 debug_stack_usage_inc();
743 /* It's safe to allow irq's after DR6 has been saved */
744 cond_local_irq_enable(regs);
746 if (v8086_mode(regs)) {
747 handle_vm86_trap((struct kernel_vm86_regs *) regs, error_code,
749 cond_local_irq_disable(regs);
750 debug_stack_usage_dec();
754 if (WARN_ON_ONCE((dr6 & DR_STEP) && !user_mode(regs))) {
756 * Historical junk that used to handle SYSENTER single-stepping.
757 * This should be unreachable now. If we survive for a while
758 * without anyone hitting this warning, we'll turn this into
761 tsk->thread.debugreg6 &= ~DR_STEP;
762 set_tsk_thread_flag(tsk, TIF_SINGLESTEP);
763 regs->flags &= ~X86_EFLAGS_TF;
765 si_code = get_si_code(tsk->thread.debugreg6);
766 if (tsk->thread.debugreg6 & (DR_STEP | DR_TRAP_BITS) || user_icebp)
767 send_sigtrap(tsk, regs, error_code, si_code);
768 cond_local_irq_disable(regs);
769 debug_stack_usage_dec();
772 #if defined(CONFIG_X86_32)
774 * This is the most likely code path that involves non-trivial use
775 * of the SYSENTER stack. Check that we haven't overrun it.
777 WARN(this_cpu_read(cpu_tss.SYSENTER_stack_canary) != STACK_END_MAGIC,
778 "Overran or corrupted SYSENTER stack\n");
782 NOKPROBE_SYMBOL(do_debug);
785 * Note that we play around with the 'TS' bit in an attempt to get
786 * the correct behaviour even in the presence of the asynchronous
789 static void math_error(struct pt_regs *regs, int error_code, int trapnr)
791 struct task_struct *task = current;
792 struct fpu *fpu = &task->thread.fpu;
794 char *str = (trapnr == X86_TRAP_MF) ? "fpu exception" :
797 if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, SIGFPE) == NOTIFY_STOP)
799 cond_local_irq_enable(regs);
801 if (!user_mode(regs)) {
802 if (!fixup_exception(regs, trapnr)) {
803 task->thread.error_code = error_code;
804 task->thread.trap_nr = trapnr;
805 die(str, regs, error_code);
811 * Save the info for the exception handler and clear the error.
815 task->thread.trap_nr = trapnr;
816 task->thread.error_code = error_code;
817 info.si_signo = SIGFPE;
819 info.si_addr = (void __user *)uprobe_get_trap_addr(regs);
821 info.si_code = fpu__exception_code(fpu, trapnr);
823 /* Retry when we get spurious exceptions: */
827 force_sig_info(SIGFPE, &info, task);
830 dotraplinkage void do_coprocessor_error(struct pt_regs *regs, long error_code)
832 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
833 math_error(regs, error_code, X86_TRAP_MF);
837 do_simd_coprocessor_error(struct pt_regs *regs, long error_code)
839 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
840 math_error(regs, error_code, X86_TRAP_XF);
844 do_spurious_interrupt_bug(struct pt_regs *regs, long error_code)
846 cond_local_irq_enable(regs);
850 do_device_not_available(struct pt_regs *regs, long error_code)
854 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
856 #ifdef CONFIG_MATH_EMULATION
857 if (!boot_cpu_has(X86_FEATURE_FPU) && (read_cr0() & X86_CR0_EM)) {
858 struct math_emu_info info = { };
860 cond_local_irq_enable(regs);
868 /* This should not happen. */
870 if (WARN(cr0 & X86_CR0_TS, "CR0.TS was set")) {
871 /* Try to fix it up and carry on. */
872 write_cr0(cr0 & ~X86_CR0_TS);
875 * Something terrible happened, and we're better off trying
876 * to kill the task than getting stuck in a never-ending
877 * loop of #NM faults.
879 die("unexpected #NM exception", regs, error_code);
882 NOKPROBE_SYMBOL(do_device_not_available);
885 dotraplinkage void do_iret_error(struct pt_regs *regs, long error_code)
889 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
892 info.si_signo = SIGILL;
894 info.si_code = ILL_BADSTK;
896 if (notify_die(DIE_TRAP, "iret exception", regs, error_code,
897 X86_TRAP_IRET, SIGILL) != NOTIFY_STOP) {
898 do_trap(X86_TRAP_IRET, SIGILL, "iret exception", regs, error_code,
904 /* Set of traps needed for early debugging. */
905 void __init early_trap_init(void)
908 * Don't use IST to set DEBUG_STACK as it doesn't work until TSS
909 * is ready in cpu_init() <-- trap_init(). Before trap_init(),
910 * CPU runs at ring 0 so it is impossible to hit an invalid
911 * stack. Using the original stack works well enough at this
912 * early stage. DEBUG_STACK will be equipped after cpu_init() in
915 * We don't need to set trace_idt_table like set_intr_gate(),
916 * since we don't have trace_debug and it will be reset to
917 * 'debug' in trap_init() by set_intr_gate_ist().
919 set_intr_gate_notrace(X86_TRAP_DB, debug);
920 /* int3 can be called from all */
921 set_system_intr_gate(X86_TRAP_BP, &int3);
923 set_intr_gate(X86_TRAP_PF, page_fault);
925 load_idt(&idt_descr);
928 void __init early_trap_pf_init(void)
931 set_intr_gate(X86_TRAP_PF, page_fault);
935 void __init trap_init(void)
940 void __iomem *p = early_ioremap(0x0FFFD9, 4);
942 if (readl(p) == 'E' + ('I'<<8) + ('S'<<16) + ('A'<<24))
947 set_intr_gate(X86_TRAP_DE, divide_error);
948 set_intr_gate_ist(X86_TRAP_NMI, &nmi, NMI_STACK);
949 /* int4 can be called from all */
950 set_system_intr_gate(X86_TRAP_OF, &overflow);
951 set_intr_gate(X86_TRAP_BR, bounds);
952 set_intr_gate(X86_TRAP_UD, invalid_op);
953 set_intr_gate(X86_TRAP_NM, device_not_available);
955 set_task_gate(X86_TRAP_DF, GDT_ENTRY_DOUBLEFAULT_TSS);
957 set_intr_gate_ist(X86_TRAP_DF, &double_fault, DOUBLEFAULT_STACK);
959 set_intr_gate(X86_TRAP_OLD_MF, coprocessor_segment_overrun);
960 set_intr_gate(X86_TRAP_TS, invalid_TSS);
961 set_intr_gate(X86_TRAP_NP, segment_not_present);
962 set_intr_gate(X86_TRAP_SS, stack_segment);
963 set_intr_gate(X86_TRAP_GP, general_protection);
964 set_intr_gate(X86_TRAP_SPURIOUS, spurious_interrupt_bug);
965 set_intr_gate(X86_TRAP_MF, coprocessor_error);
966 set_intr_gate(X86_TRAP_AC, alignment_check);
967 #ifdef CONFIG_X86_MCE
968 set_intr_gate_ist(X86_TRAP_MC, &machine_check, MCE_STACK);
970 set_intr_gate(X86_TRAP_XF, simd_coprocessor_error);
972 /* Reserve all the builtin and the syscall vector: */
973 for (i = 0; i < FIRST_EXTERNAL_VECTOR; i++)
974 set_bit(i, used_vectors);
976 #ifdef CONFIG_IA32_EMULATION
977 set_system_intr_gate(IA32_SYSCALL_VECTOR, entry_INT80_compat);
978 set_bit(IA32_SYSCALL_VECTOR, used_vectors);
982 set_system_intr_gate(IA32_SYSCALL_VECTOR, entry_INT80_32);
983 set_bit(IA32_SYSCALL_VECTOR, used_vectors);
987 * Set the IDT descriptor to a fixed read-only location, so that the
988 * "sidt" instruction will not leak the location of the kernel, and
989 * to defend the IDT against arbitrary memory write vulnerabilities.
990 * It will be reloaded in cpu_init() */
991 __set_fixmap(FIX_RO_IDT, __pa_symbol(idt_table), PAGE_KERNEL_RO);
992 idt_descr.address = fix_to_virt(FIX_RO_IDT);
995 * Should be a barrier for any external CPU state:
1000 * X86_TRAP_DB and X86_TRAP_BP have been set
1001 * in early_trap_init(). However, ITS works only after
1002 * cpu_init() loads TSS. See comments in early_trap_init().
1004 set_intr_gate_ist(X86_TRAP_DB, &debug, DEBUG_STACK);
1005 /* int3 can be called from all */
1006 set_system_intr_gate_ist(X86_TRAP_BP, &int3, DEBUG_STACK);
1008 x86_init.irqs.trap_init();
1010 #ifdef CONFIG_X86_64
1011 memcpy(&debug_idt_table, &idt_table, IDT_ENTRIES * 16);
1012 set_nmi_gate(X86_TRAP_DB, &debug);
1013 set_nmi_gate(X86_TRAP_BP, &int3);