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/timer.h>
33 #include <linux/init.h>
34 #include <linux/bug.h>
35 #include <linux/nmi.h>
37 #include <linux/smp.h>
41 #include <linux/ioport.h>
42 #include <linux/eisa.h>
45 #if defined(CONFIG_EDAC)
46 #include <linux/edac.h>
49 #include <asm/kmemcheck.h>
50 #include <asm/stacktrace.h>
51 #include <asm/processor.h>
52 #include <asm/debugreg.h>
53 #include <linux/atomic.h>
54 #include <asm/text-patching.h>
55 #include <asm/ftrace.h>
56 #include <asm/traps.h>
58 #include <asm/fpu/internal.h>
60 #include <asm/fixmap.h>
61 #include <asm/mach_traps.h>
62 #include <asm/alternative.h>
63 #include <asm/fpu/xstate.h>
64 #include <asm/trace/mpx.h>
69 #include <asm/x86_init.h>
70 #include <asm/pgalloc.h>
71 #include <asm/proto.h>
73 /* No need to be aligned, but done to keep all IDTs defined the same way. */
74 gate_desc debug_idt_table[NR_VECTORS] __page_aligned_bss;
76 #include <asm/processor-flags.h>
77 #include <asm/setup.h>
78 #include <asm/proto.h>
81 /* Must be page-aligned because the real IDT is used in a fixmap. */
82 gate_desc idt_table[NR_VECTORS] __page_aligned_bss;
84 DECLARE_BITMAP(used_vectors, NR_VECTORS);
85 EXPORT_SYMBOL_GPL(used_vectors);
87 static inline void cond_local_irq_enable(struct pt_regs *regs)
89 if (regs->flags & X86_EFLAGS_IF)
93 static inline void cond_local_irq_disable(struct pt_regs *regs)
95 if (regs->flags & X86_EFLAGS_IF)
100 * In IST context, we explicitly disable preemption. This serves two
101 * purposes: it makes it much less likely that we would accidentally
102 * schedule in IST context and it will force a warning if we somehow
103 * manage to schedule by accident.
105 void ist_enter(struct pt_regs *regs)
107 if (user_mode(regs)) {
108 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
111 * We might have interrupted pretty much anything. In
112 * fact, if we're a machine check, we can even interrupt
113 * NMI processing. We don't want in_nmi() to return true,
114 * but we need to notify RCU.
121 /* This code is a bit fragile. Test it. */
122 RCU_LOCKDEP_WARN(!rcu_is_watching(), "ist_enter didn't work");
125 void ist_exit(struct pt_regs *regs)
127 preempt_enable_no_resched();
129 if (!user_mode(regs))
134 * ist_begin_non_atomic() - begin a non-atomic section in an IST exception
135 * @regs: regs passed to the IST exception handler
137 * IST exception handlers normally cannot schedule. As a special
138 * exception, if the exception interrupted userspace code (i.e.
139 * user_mode(regs) would return true) and the exception was not
140 * a double fault, it can be safe to schedule. ist_begin_non_atomic()
141 * begins a non-atomic section within an ist_enter()/ist_exit() region.
142 * Callers are responsible for enabling interrupts themselves inside
143 * the non-atomic section, and callers must call ist_end_non_atomic()
146 void ist_begin_non_atomic(struct pt_regs *regs)
148 BUG_ON(!user_mode(regs));
151 * Sanity check: we need to be on the normal thread stack. This
152 * will catch asm bugs and any attempt to use ist_preempt_enable
155 BUG_ON((unsigned long)(current_top_of_stack() -
156 current_stack_pointer()) >= THREAD_SIZE);
158 preempt_enable_no_resched();
162 * ist_end_non_atomic() - begin a non-atomic section in an IST exception
164 * Ends a non-atomic section started with ist_begin_non_atomic().
166 void ist_end_non_atomic(void)
171 static nokprobe_inline int
172 do_trap_no_signal(struct task_struct *tsk, int trapnr, char *str,
173 struct pt_regs *regs, long error_code)
175 if (v8086_mode(regs)) {
177 * Traps 0, 1, 3, 4, and 5 should be forwarded to vm86.
178 * On nmi (interrupt 2), do_trap should not be called.
180 if (trapnr < X86_TRAP_UD) {
181 if (!handle_vm86_trap((struct kernel_vm86_regs *) regs,
188 if (!user_mode(regs)) {
189 if (!fixup_exception(regs, trapnr)) {
190 tsk->thread.error_code = error_code;
191 tsk->thread.trap_nr = trapnr;
192 die(str, regs, error_code);
200 static siginfo_t *fill_trap_info(struct pt_regs *regs, int signr, int trapnr,
203 unsigned long siaddr;
208 return SEND_SIG_PRIV;
212 siaddr = uprobe_get_trap_addr(regs);
216 siaddr = uprobe_get_trap_addr(regs);
224 info->si_signo = signr;
226 info->si_code = sicode;
227 info->si_addr = (void __user *)siaddr;
232 do_trap(int trapnr, int signr, char *str, struct pt_regs *regs,
233 long error_code, siginfo_t *info)
235 struct task_struct *tsk = current;
238 if (!do_trap_no_signal(tsk, trapnr, str, regs, error_code))
241 * We want error_code and trap_nr set for userspace faults and
242 * kernelspace faults which result in die(), but not
243 * kernelspace faults which are fixed up. die() gives the
244 * process no chance to handle the signal and notice the
245 * kernel fault information, so that won't result in polluting
246 * the information about previously queued, but not yet
247 * delivered, faults. See also do_general_protection below.
249 tsk->thread.error_code = error_code;
250 tsk->thread.trap_nr = trapnr;
252 if (show_unhandled_signals && unhandled_signal(tsk, signr) &&
253 printk_ratelimit()) {
254 pr_info("%s[%d] trap %s ip:%lx sp:%lx error:%lx",
255 tsk->comm, tsk->pid, str,
256 regs->ip, regs->sp, error_code);
257 print_vma_addr(" in ", regs->ip);
261 force_sig_info(signr, info ?: SEND_SIG_PRIV, tsk);
263 NOKPROBE_SYMBOL(do_trap);
265 static void do_error_trap(struct pt_regs *regs, long error_code, char *str,
266 unsigned long trapnr, int signr)
270 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
272 if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) !=
274 cond_local_irq_enable(regs);
275 do_trap(trapnr, signr, str, regs, error_code,
276 fill_trap_info(regs, signr, trapnr, &info));
280 #define DO_ERROR(trapnr, signr, str, name) \
281 dotraplinkage void do_##name(struct pt_regs *regs, long error_code) \
283 do_error_trap(regs, error_code, str, trapnr, signr); \
286 DO_ERROR(X86_TRAP_DE, SIGFPE, "divide error", divide_error)
287 DO_ERROR(X86_TRAP_OF, SIGSEGV, "overflow", overflow)
288 DO_ERROR(X86_TRAP_UD, SIGILL, "invalid opcode", invalid_op)
289 DO_ERROR(X86_TRAP_OLD_MF, SIGFPE, "coprocessor segment overrun",coprocessor_segment_overrun)
290 DO_ERROR(X86_TRAP_TS, SIGSEGV, "invalid TSS", invalid_TSS)
291 DO_ERROR(X86_TRAP_NP, SIGBUS, "segment not present", segment_not_present)
292 DO_ERROR(X86_TRAP_SS, SIGBUS, "stack segment", stack_segment)
293 DO_ERROR(X86_TRAP_AC, SIGBUS, "alignment check", alignment_check)
295 #ifdef CONFIG_VMAP_STACK
296 __visible void __noreturn handle_stack_overflow(const char *message,
297 struct pt_regs *regs,
298 unsigned long fault_address)
300 printk(KERN_EMERG "BUG: stack guard page was hit at %p (stack is %p..%p)\n",
301 (void *)fault_address, current->stack,
302 (char *)current->stack + THREAD_SIZE - 1);
303 die(message, regs, 0);
305 /* Be absolutely certain we don't return. */
311 /* Runs on IST stack */
312 dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code)
314 static const char str[] = "double fault";
315 struct task_struct *tsk = current;
316 #ifdef CONFIG_VMAP_STACK
320 #ifdef CONFIG_X86_ESPFIX64
321 extern unsigned char native_irq_return_iret[];
324 * If IRET takes a non-IST fault on the espfix64 stack, then we
325 * end up promoting it to a doublefault. In that case, modify
326 * the stack to make it look like we just entered the #GP
327 * handler from user space, similar to bad_iret.
329 * No need for ist_enter here because we don't use RCU.
331 if (((long)regs->sp >> PGDIR_SHIFT) == ESPFIX_PGD_ENTRY &&
332 regs->cs == __KERNEL_CS &&
333 regs->ip == (unsigned long)native_irq_return_iret)
335 struct pt_regs *normal_regs = task_pt_regs(current);
337 /* Fake a #GP(0) from userspace. */
338 memmove(&normal_regs->ip, (void *)regs->sp, 5*8);
339 normal_regs->orig_ax = 0; /* Missing (lost) #GP error code */
340 regs->ip = (unsigned long)general_protection;
341 regs->sp = (unsigned long)&normal_regs->orig_ax;
348 notify_die(DIE_TRAP, str, regs, error_code, X86_TRAP_DF, SIGSEGV);
350 tsk->thread.error_code = error_code;
351 tsk->thread.trap_nr = X86_TRAP_DF;
353 #ifdef CONFIG_VMAP_STACK
355 * If we overflow the stack into a guard page, the CPU will fail
356 * to deliver #PF and will send #DF instead. Similarly, if we
357 * take any non-IST exception while too close to the bottom of
358 * the stack, the processor will get a page fault while
359 * delivering the exception and will generate a double fault.
361 * According to the SDM (footnote in 6.15 under "Interrupt 14 -
362 * Page-Fault Exception (#PF):
364 * Processors update CR2 whenever a page fault is detected. If a
365 * second page fault occurs while an earlier page fault is being
366 * deliv- ered, the faulting linear address of the second fault will
367 * overwrite the contents of CR2 (replacing the previous
368 * address). These updates to CR2 occur even if the page fault
369 * results in a double fault or occurs during the delivery of a
372 * The logic below has a small possibility of incorrectly diagnosing
373 * some errors as stack overflows. For example, if the IDT or GDT
374 * gets corrupted such that #GP delivery fails due to a bad descriptor
375 * causing #GP and we hit this condition while CR2 coincidentally
376 * points to the stack guard page, we'll think we overflowed the
377 * stack. Given that we're going to panic one way or another
378 * if this happens, this isn't necessarily worth fixing.
380 * If necessary, we could improve the test by only diagnosing
381 * a stack overflow if the saved RSP points within 47 bytes of
382 * the bottom of the stack: if RSP == tsk_stack + 48 and we
383 * take an exception, the stack is already aligned and there
384 * will be enough room SS, RSP, RFLAGS, CS, RIP, and a
385 * possible error code, so a stack overflow would *not* double
386 * fault. With any less space left, exception delivery could
387 * fail, and, as a practical matter, we've overflowed the
388 * stack even if the actual trigger for the double fault was
392 if ((unsigned long)task_stack_page(tsk) - 1 - cr2 < PAGE_SIZE)
393 handle_stack_overflow("kernel stack overflow (double-fault)", regs, cr2);
396 #ifdef CONFIG_DOUBLEFAULT
397 df_debug(regs, error_code);
400 * This is always a kernel trap and never fixable (and thus must
404 die(str, regs, error_code);
408 dotraplinkage void do_bounds(struct pt_regs *regs, long error_code)
410 const struct mpx_bndcsr *bndcsr;
413 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
414 if (notify_die(DIE_TRAP, "bounds", regs, error_code,
415 X86_TRAP_BR, SIGSEGV) == NOTIFY_STOP)
417 cond_local_irq_enable(regs);
419 if (!user_mode(regs))
420 die("bounds", regs, error_code);
422 if (!cpu_feature_enabled(X86_FEATURE_MPX)) {
423 /* The exception is not from Intel MPX */
428 * We need to look at BNDSTATUS to resolve this exception.
429 * A NULL here might mean that it is in its 'init state',
430 * which is all zeros which indicates MPX was not
431 * responsible for the exception.
433 bndcsr = get_xsave_field_ptr(XFEATURE_MASK_BNDCSR);
437 trace_bounds_exception_mpx(bndcsr);
439 * The error code field of the BNDSTATUS register communicates status
440 * information of a bound range exception #BR or operation involving
443 switch (bndcsr->bndstatus & MPX_BNDSTA_ERROR_CODE) {
444 case 2: /* Bound directory has invalid entry. */
445 if (mpx_handle_bd_fault())
447 break; /* Success, it was handled */
448 case 1: /* Bound violation. */
449 info = mpx_generate_siginfo(regs);
452 * We failed to decode the MPX instruction. Act as if
453 * the exception was not caused by MPX.
458 * Success, we decoded the instruction and retrieved
459 * an 'info' containing the address being accessed
460 * which caused the exception. This information
461 * allows and application to possibly handle the
462 * #BR exception itself.
464 do_trap(X86_TRAP_BR, SIGSEGV, "bounds", regs, error_code, info);
467 case 0: /* No exception caused by Intel MPX operations. */
470 die("bounds", regs, error_code);
477 * This path out is for all the cases where we could not
478 * handle the exception in some way (like allocating a
479 * table or telling userspace about it. We will also end
480 * up here if the kernel has MPX turned off at compile
483 do_trap(X86_TRAP_BR, SIGSEGV, "bounds", regs, error_code, NULL);
487 do_general_protection(struct pt_regs *regs, long error_code)
489 struct task_struct *tsk;
491 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
492 cond_local_irq_enable(regs);
494 if (v8086_mode(regs)) {
496 handle_vm86_fault((struct kernel_vm86_regs *) regs, error_code);
501 if (!user_mode(regs)) {
502 if (fixup_exception(regs, X86_TRAP_GP))
505 tsk->thread.error_code = error_code;
506 tsk->thread.trap_nr = X86_TRAP_GP;
507 if (notify_die(DIE_GPF, "general protection fault", regs, error_code,
508 X86_TRAP_GP, SIGSEGV) != NOTIFY_STOP)
509 die("general protection fault", regs, error_code);
513 tsk->thread.error_code = error_code;
514 tsk->thread.trap_nr = X86_TRAP_GP;
516 if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) &&
517 printk_ratelimit()) {
518 pr_info("%s[%d] general protection ip:%lx sp:%lx error:%lx",
519 tsk->comm, task_pid_nr(tsk),
520 regs->ip, regs->sp, error_code);
521 print_vma_addr(" in ", regs->ip);
525 force_sig_info(SIGSEGV, SEND_SIG_PRIV, tsk);
527 NOKPROBE_SYMBOL(do_general_protection);
529 /* May run on IST stack. */
530 dotraplinkage void notrace do_int3(struct pt_regs *regs, long error_code)
532 #ifdef CONFIG_DYNAMIC_FTRACE
534 * ftrace must be first, everything else may cause a recursive crash.
535 * See note by declaration of modifying_ftrace_code in ftrace.c
537 if (unlikely(atomic_read(&modifying_ftrace_code)) &&
538 ftrace_int3_handler(regs))
541 if (poke_int3_handler(regs))
545 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
546 #ifdef CONFIG_KGDB_LOW_LEVEL_TRAP
547 if (kgdb_ll_trap(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP,
548 SIGTRAP) == NOTIFY_STOP)
550 #endif /* CONFIG_KGDB_LOW_LEVEL_TRAP */
552 #ifdef CONFIG_KPROBES
553 if (kprobe_int3_handler(regs))
557 if (notify_die(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP,
558 SIGTRAP) == NOTIFY_STOP)
562 * Let others (NMI) know that the debug stack is in use
563 * as we may switch to the interrupt stack.
565 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 preempt_enable_no_resched();
571 debug_stack_usage_dec();
575 NOKPROBE_SYMBOL(do_int3);
579 * Help handler running on IST stack to switch off the IST stack if the
580 * interrupted code was in user mode. The actual stack switch is done in
583 asmlinkage __visible notrace struct pt_regs *sync_regs(struct pt_regs *eregs)
585 struct pt_regs *regs = task_pt_regs(current);
589 NOKPROBE_SYMBOL(sync_regs);
591 struct bad_iret_stack {
592 void *error_entry_ret;
596 asmlinkage __visible notrace
597 struct bad_iret_stack *fixup_bad_iret(struct bad_iret_stack *s)
600 * This is called from entry_64.S early in handling a fault
601 * caused by a bad iret to user mode. To handle the fault
602 * correctly, we want move our stack frame to task_pt_regs
603 * and we want to pretend that the exception came from the
606 struct bad_iret_stack *new_stack =
607 container_of(task_pt_regs(current),
608 struct bad_iret_stack, regs);
610 /* Copy the IRET target to the new stack. */
611 memmove(&new_stack->regs.ip, (void *)s->regs.sp, 5*8);
613 /* Copy the remainder of the stack from the current stack. */
614 memmove(new_stack, s, offsetof(struct bad_iret_stack, regs.ip));
616 BUG_ON(!user_mode(&new_stack->regs));
619 NOKPROBE_SYMBOL(fixup_bad_iret);
622 static bool is_sysenter_singlestep(struct pt_regs *regs)
625 * We don't try for precision here. If we're anywhere in the region of
626 * code that can be single-stepped in the SYSENTER entry path, then
627 * assume that this is a useless single-step trap due to SYSENTER
628 * being invoked with TF set. (We don't know in advance exactly
629 * which instructions will be hit because BTF could plausibly
633 return (regs->ip - (unsigned long)__begin_SYSENTER_singlestep_region) <
634 (unsigned long)__end_SYSENTER_singlestep_region -
635 (unsigned long)__begin_SYSENTER_singlestep_region;
636 #elif defined(CONFIG_IA32_EMULATION)
637 return (regs->ip - (unsigned long)entry_SYSENTER_compat) <
638 (unsigned long)__end_entry_SYSENTER_compat -
639 (unsigned long)entry_SYSENTER_compat;
646 * Our handling of the processor debug registers is non-trivial.
647 * We do not clear them on entry and exit from the kernel. Therefore
648 * it is possible to get a watchpoint trap here from inside the kernel.
649 * However, the code in ./ptrace.c has ensured that the user can
650 * only set watchpoints on userspace addresses. Therefore the in-kernel
651 * watchpoint trap can only occur in code which is reading/writing
652 * from user space. Such code must not hold kernel locks (since it
653 * can equally take a page fault), therefore it is safe to call
654 * force_sig_info even though that claims and releases locks.
656 * Code in ./signal.c ensures that the debug control register
657 * is restored before we deliver any signal, and therefore that
658 * user code runs with the correct debug control register even though
661 * Being careful here means that we don't have to be as careful in a
662 * lot of more complicated places (task switching can be a bit lazy
663 * about restoring all the debug state, and ptrace doesn't have to
664 * find every occurrence of the TF bit that could be saved away even
667 * May run on IST stack.
669 dotraplinkage void do_debug(struct pt_regs *regs, long error_code)
671 struct task_struct *tsk = current;
678 get_debugreg(dr6, 6);
680 * The Intel SDM says:
682 * Certain debug exceptions may clear bits 0-3. The remaining
683 * contents of the DR6 register are never cleared by the
684 * processor. To avoid confusion in identifying debug
685 * exceptions, debug handlers should clear the register before
686 * returning to the interrupted task.
688 * Keep it simple: clear DR6 immediately.
692 /* Filter out all the reserved bits which are preset to 1 */
693 dr6 &= ~DR6_RESERVED;
696 * The SDM says "The processor clears the BTF flag when it
697 * generates a debug exception." Clear TIF_BLOCKSTEP to keep
698 * TIF_BLOCKSTEP in sync with the hardware BTF flag.
700 clear_tsk_thread_flag(tsk, TIF_BLOCKSTEP);
702 if (unlikely(!user_mode(regs) && (dr6 & DR_STEP) &&
703 is_sysenter_singlestep(regs))) {
708 * else we might have gotten a single-step trap and hit a
709 * watchpoint at the same time, in which case we should fall
710 * through and handle the watchpoint.
715 * If dr6 has no reason to give us about the origin of this trap,
716 * then it's very likely the result of an icebp/int01 trap.
717 * User wants a sigtrap for that.
719 if (!dr6 && user_mode(regs))
722 /* Catch kmemcheck conditions! */
723 if ((dr6 & DR_STEP) && kmemcheck_trap(regs))
726 /* Store the virtualized DR6 value */
727 tsk->thread.debugreg6 = dr6;
729 #ifdef CONFIG_KPROBES
730 if (kprobe_debug_handler(regs))
734 if (notify_die(DIE_DEBUG, "debug", regs, (long)&dr6, error_code,
735 SIGTRAP) == NOTIFY_STOP)
739 * Let others (NMI) know that the debug stack is in use
740 * as we may switch to the interrupt stack.
742 debug_stack_usage_inc();
744 /* It's safe to allow irq's after DR6 has been saved */
746 cond_local_irq_enable(regs);
748 if (v8086_mode(regs)) {
749 handle_vm86_trap((struct kernel_vm86_regs *) regs, error_code,
751 cond_local_irq_disable(regs);
752 preempt_enable_no_resched();
753 debug_stack_usage_dec();
757 if (WARN_ON_ONCE((dr6 & DR_STEP) && !user_mode(regs))) {
759 * Historical junk that used to handle SYSENTER single-stepping.
760 * This should be unreachable now. If we survive for a while
761 * without anyone hitting this warning, we'll turn this into
764 tsk->thread.debugreg6 &= ~DR_STEP;
765 set_tsk_thread_flag(tsk, TIF_SINGLESTEP);
766 regs->flags &= ~X86_EFLAGS_TF;
768 si_code = get_si_code(tsk->thread.debugreg6);
769 if (tsk->thread.debugreg6 & (DR_STEP | DR_TRAP_BITS) || user_icebp)
770 send_sigtrap(tsk, regs, error_code, si_code);
771 cond_local_irq_disable(regs);
772 preempt_enable_no_resched();
773 debug_stack_usage_dec();
776 #if defined(CONFIG_X86_32)
778 * This is the most likely code path that involves non-trivial use
779 * of the SYSENTER stack. Check that we haven't overrun it.
781 WARN(this_cpu_read(cpu_tss.SYSENTER_stack_canary) != STACK_END_MAGIC,
782 "Overran or corrupted SYSENTER stack\n");
786 NOKPROBE_SYMBOL(do_debug);
789 * Note that we play around with the 'TS' bit in an attempt to get
790 * the correct behaviour even in the presence of the asynchronous
793 static void math_error(struct pt_regs *regs, int error_code, int trapnr)
795 struct task_struct *task = current;
796 struct fpu *fpu = &task->thread.fpu;
798 char *str = (trapnr == X86_TRAP_MF) ? "fpu exception" :
801 if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, SIGFPE) == NOTIFY_STOP)
803 cond_local_irq_enable(regs);
805 if (!user_mode(regs)) {
806 if (!fixup_exception(regs, trapnr)) {
807 task->thread.error_code = error_code;
808 task->thread.trap_nr = trapnr;
809 die(str, regs, error_code);
815 * Save the info for the exception handler and clear the error.
819 task->thread.trap_nr = trapnr;
820 task->thread.error_code = error_code;
821 info.si_signo = SIGFPE;
823 info.si_addr = (void __user *)uprobe_get_trap_addr(regs);
825 info.si_code = fpu__exception_code(fpu, trapnr);
827 /* Retry when we get spurious exceptions: */
831 force_sig_info(SIGFPE, &info, task);
834 dotraplinkage void do_coprocessor_error(struct pt_regs *regs, long error_code)
836 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
837 math_error(regs, error_code, X86_TRAP_MF);
841 do_simd_coprocessor_error(struct pt_regs *regs, long error_code)
843 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
844 math_error(regs, error_code, X86_TRAP_XF);
848 do_spurious_interrupt_bug(struct pt_regs *regs, long error_code)
850 cond_local_irq_enable(regs);
854 do_device_not_available(struct pt_regs *regs, long error_code)
856 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
858 #ifdef CONFIG_MATH_EMULATION
859 if (!boot_cpu_has(X86_FEATURE_FPU) && (read_cr0() & X86_CR0_EM)) {
860 struct math_emu_info info = { };
862 cond_local_irq_enable(regs);
869 fpu__restore(¤t->thread.fpu); /* interrupts still off */
871 cond_local_irq_enable(regs);
874 NOKPROBE_SYMBOL(do_device_not_available);
877 dotraplinkage void do_iret_error(struct pt_regs *regs, long error_code)
881 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
884 info.si_signo = SIGILL;
886 info.si_code = ILL_BADSTK;
888 if (notify_die(DIE_TRAP, "iret exception", regs, error_code,
889 X86_TRAP_IRET, SIGILL) != NOTIFY_STOP) {
890 do_trap(X86_TRAP_IRET, SIGILL, "iret exception", regs, error_code,
896 /* Set of traps needed for early debugging. */
897 void __init early_trap_init(void)
900 * Don't use IST to set DEBUG_STACK as it doesn't work until TSS
901 * is ready in cpu_init() <-- trap_init(). Before trap_init(),
902 * CPU runs at ring 0 so it is impossible to hit an invalid
903 * stack. Using the original stack works well enough at this
904 * early stage. DEBUG_STACK will be equipped after cpu_init() in
907 * We don't need to set trace_idt_table like set_intr_gate(),
908 * since we don't have trace_debug and it will be reset to
909 * 'debug' in trap_init() by set_intr_gate_ist().
911 set_intr_gate_notrace(X86_TRAP_DB, debug);
912 /* int3 can be called from all */
913 set_system_intr_gate(X86_TRAP_BP, &int3);
915 set_intr_gate(X86_TRAP_PF, page_fault);
917 load_idt(&idt_descr);
920 void __init early_trap_pf_init(void)
923 set_intr_gate(X86_TRAP_PF, page_fault);
927 void __init trap_init(void)
932 void __iomem *p = early_ioremap(0x0FFFD9, 4);
934 if (readl(p) == 'E' + ('I'<<8) + ('S'<<16) + ('A'<<24))
939 set_intr_gate(X86_TRAP_DE, divide_error);
940 set_intr_gate_ist(X86_TRAP_NMI, &nmi, NMI_STACK);
941 /* int4 can be called from all */
942 set_system_intr_gate(X86_TRAP_OF, &overflow);
943 set_intr_gate(X86_TRAP_BR, bounds);
944 set_intr_gate(X86_TRAP_UD, invalid_op);
945 set_intr_gate(X86_TRAP_NM, device_not_available);
947 set_task_gate(X86_TRAP_DF, GDT_ENTRY_DOUBLEFAULT_TSS);
949 set_intr_gate_ist(X86_TRAP_DF, &double_fault, DOUBLEFAULT_STACK);
951 set_intr_gate(X86_TRAP_OLD_MF, coprocessor_segment_overrun);
952 set_intr_gate(X86_TRAP_TS, invalid_TSS);
953 set_intr_gate(X86_TRAP_NP, segment_not_present);
954 set_intr_gate(X86_TRAP_SS, stack_segment);
955 set_intr_gate(X86_TRAP_GP, general_protection);
956 set_intr_gate(X86_TRAP_SPURIOUS, spurious_interrupt_bug);
957 set_intr_gate(X86_TRAP_MF, coprocessor_error);
958 set_intr_gate(X86_TRAP_AC, alignment_check);
959 #ifdef CONFIG_X86_MCE
960 set_intr_gate_ist(X86_TRAP_MC, &machine_check, MCE_STACK);
962 set_intr_gate(X86_TRAP_XF, simd_coprocessor_error);
964 /* Reserve all the builtin and the syscall vector: */
965 for (i = 0; i < FIRST_EXTERNAL_VECTOR; i++)
966 set_bit(i, used_vectors);
968 #ifdef CONFIG_IA32_EMULATION
969 set_system_intr_gate(IA32_SYSCALL_VECTOR, entry_INT80_compat);
970 set_bit(IA32_SYSCALL_VECTOR, used_vectors);
974 set_system_intr_gate(IA32_SYSCALL_VECTOR, entry_INT80_32);
975 set_bit(IA32_SYSCALL_VECTOR, used_vectors);
979 * Set the IDT descriptor to a fixed read-only location, so that the
980 * "sidt" instruction will not leak the location of the kernel, and
981 * to defend the IDT against arbitrary memory write vulnerabilities.
982 * It will be reloaded in cpu_init() */
983 __set_fixmap(FIX_RO_IDT, __pa_symbol(idt_table), PAGE_KERNEL_RO);
984 idt_descr.address = fix_to_virt(FIX_RO_IDT);
987 * Should be a barrier for any external CPU state:
992 * X86_TRAP_DB and X86_TRAP_BP have been set
993 * in early_trap_init(). However, ITS works only after
994 * cpu_init() loads TSS. See comments in early_trap_init().
996 set_intr_gate_ist(X86_TRAP_DB, &debug, DEBUG_STACK);
997 /* int3 can be called from all */
998 set_system_intr_gate_ist(X86_TRAP_BP, &int3, DEBUG_STACK);
1000 x86_init.irqs.trap_init();
1002 #ifdef CONFIG_X86_64
1003 memcpy(&debug_idt_table, &idt_table, IDT_ENTRIES * 16);
1004 set_nmi_gate(X86_TRAP_DB, &debug);
1005 set_nmi_gate(X86_TRAP_BP, &int3);