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>
41 #if defined(CONFIG_EDAC)
42 #include <linux/edac.h>
45 #include <asm/stacktrace.h>
46 #include <asm/processor.h>
47 #include <asm/debugreg.h>
48 #include <linux/atomic.h>
49 #include <asm/text-patching.h>
50 #include <asm/ftrace.h>
51 #include <asm/traps.h>
53 #include <asm/fpu/internal.h>
55 #include <asm/fixmap.h>
56 #include <asm/mach_traps.h>
57 #include <asm/alternative.h>
58 #include <asm/fpu/xstate.h>
59 #include <asm/trace/mpx.h>
65 #include <asm/x86_init.h>
66 #include <asm/pgalloc.h>
67 #include <asm/proto.h>
69 #include <asm/processor-flags.h>
70 #include <asm/setup.h>
71 #include <asm/proto.h>
74 DECLARE_BITMAP(system_vectors, NR_VECTORS);
76 static inline void cond_local_irq_enable(struct pt_regs *regs)
78 if (regs->flags & X86_EFLAGS_IF)
82 static inline void cond_local_irq_disable(struct pt_regs *regs)
84 if (regs->flags & X86_EFLAGS_IF)
89 * In IST context, we explicitly disable preemption. This serves two
90 * purposes: it makes it much less likely that we would accidentally
91 * schedule in IST context and it will force a warning if we somehow
92 * manage to schedule by accident.
94 void ist_enter(struct pt_regs *regs)
96 if (user_mode(regs)) {
97 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
100 * We might have interrupted pretty much anything. In
101 * fact, if we're a machine check, we can even interrupt
102 * NMI processing. We don't want in_nmi() to return true,
103 * but we need to notify RCU.
110 /* This code is a bit fragile. Test it. */
111 RCU_LOCKDEP_WARN(!rcu_is_watching(), "ist_enter didn't work");
114 void ist_exit(struct pt_regs *regs)
116 preempt_enable_no_resched();
118 if (!user_mode(regs))
123 * ist_begin_non_atomic() - begin a non-atomic section in an IST exception
124 * @regs: regs passed to the IST exception handler
126 * IST exception handlers normally cannot schedule. As a special
127 * exception, if the exception interrupted userspace code (i.e.
128 * user_mode(regs) would return true) and the exception was not
129 * a double fault, it can be safe to schedule. ist_begin_non_atomic()
130 * begins a non-atomic section within an ist_enter()/ist_exit() region.
131 * Callers are responsible for enabling interrupts themselves inside
132 * the non-atomic section, and callers must call ist_end_non_atomic()
135 void ist_begin_non_atomic(struct pt_regs *regs)
137 BUG_ON(!user_mode(regs));
140 * Sanity check: we need to be on the normal thread stack. This
141 * will catch asm bugs and any attempt to use ist_preempt_enable
144 BUG_ON(!on_thread_stack());
146 preempt_enable_no_resched();
150 * ist_end_non_atomic() - begin a non-atomic section in an IST exception
152 * Ends a non-atomic section started with ist_begin_non_atomic().
154 void ist_end_non_atomic(void)
159 int is_valid_bugaddr(unsigned long addr)
163 if (addr < TASK_SIZE_MAX)
166 if (probe_kernel_address((unsigned short *)addr, ud))
169 return ud == INSN_UD0 || ud == INSN_UD2;
172 int fixup_bug(struct pt_regs *regs, int trapnr)
174 if (trapnr != X86_TRAP_UD)
177 switch (report_bug(regs->ip, regs)) {
178 case BUG_TRAP_TYPE_NONE:
179 case BUG_TRAP_TYPE_BUG:
182 case BUG_TRAP_TYPE_WARN:
190 static nokprobe_inline int
191 do_trap_no_signal(struct task_struct *tsk, int trapnr, char *str,
192 struct pt_regs *regs, long error_code)
194 if (v8086_mode(regs)) {
196 * Traps 0, 1, 3, 4, and 5 should be forwarded to vm86.
197 * On nmi (interrupt 2), do_trap should not be called.
199 if (trapnr < X86_TRAP_UD) {
200 if (!handle_vm86_trap((struct kernel_vm86_regs *) regs,
207 if (!user_mode(regs)) {
208 if (fixup_exception(regs, trapnr))
211 tsk->thread.error_code = error_code;
212 tsk->thread.trap_nr = trapnr;
213 die(str, regs, error_code);
219 static siginfo_t *fill_trap_info(struct pt_regs *regs, int signr, int trapnr,
222 unsigned long siaddr;
227 return SEND_SIG_PRIV;
231 siaddr = uprobe_get_trap_addr(regs);
235 siaddr = uprobe_get_trap_addr(regs);
243 info->si_signo = signr;
245 info->si_code = sicode;
246 info->si_addr = (void __user *)siaddr;
251 do_trap(int trapnr, int signr, char *str, struct pt_regs *regs,
252 long error_code, siginfo_t *info)
254 struct task_struct *tsk = current;
257 if (!do_trap_no_signal(tsk, trapnr, str, regs, error_code))
260 * We want error_code and trap_nr set for userspace faults and
261 * kernelspace faults which result in die(), but not
262 * kernelspace faults which are fixed up. die() gives the
263 * process no chance to handle the signal and notice the
264 * kernel fault information, so that won't result in polluting
265 * the information about previously queued, but not yet
266 * delivered, faults. See also do_general_protection below.
268 tsk->thread.error_code = error_code;
269 tsk->thread.trap_nr = trapnr;
271 if (show_unhandled_signals && unhandled_signal(tsk, signr) &&
272 printk_ratelimit()) {
273 pr_info("%s[%d] trap %s ip:%lx sp:%lx error:%lx",
274 tsk->comm, tsk->pid, str,
275 regs->ip, regs->sp, error_code);
276 print_vma_addr(KERN_CONT " in ", regs->ip);
280 force_sig_info(signr, info ?: SEND_SIG_PRIV, tsk);
282 NOKPROBE_SYMBOL(do_trap);
284 static void do_error_trap(struct pt_regs *regs, long error_code, char *str,
285 unsigned long trapnr, int signr)
289 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
292 * WARN*()s end up here; fix them up before we call the
295 if (!user_mode(regs) && fixup_bug(regs, trapnr))
298 if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) !=
300 cond_local_irq_enable(regs);
301 do_trap(trapnr, signr, str, regs, error_code,
302 fill_trap_info(regs, signr, trapnr, &info));
306 #define DO_ERROR(trapnr, signr, str, name) \
307 dotraplinkage void do_##name(struct pt_regs *regs, long error_code) \
309 do_error_trap(regs, error_code, str, trapnr, signr); \
312 DO_ERROR(X86_TRAP_DE, SIGFPE, "divide error", divide_error)
313 DO_ERROR(X86_TRAP_OF, SIGSEGV, "overflow", overflow)
314 DO_ERROR(X86_TRAP_UD, SIGILL, "invalid opcode", invalid_op)
315 DO_ERROR(X86_TRAP_OLD_MF, SIGFPE, "coprocessor segment overrun",coprocessor_segment_overrun)
316 DO_ERROR(X86_TRAP_TS, SIGSEGV, "invalid TSS", invalid_TSS)
317 DO_ERROR(X86_TRAP_NP, SIGBUS, "segment not present", segment_not_present)
318 DO_ERROR(X86_TRAP_SS, SIGBUS, "stack segment", stack_segment)
319 DO_ERROR(X86_TRAP_AC, SIGBUS, "alignment check", alignment_check)
321 #ifdef CONFIG_VMAP_STACK
322 __visible void __noreturn handle_stack_overflow(const char *message,
323 struct pt_regs *regs,
324 unsigned long fault_address)
326 printk(KERN_EMERG "BUG: stack guard page was hit at %p (stack is %p..%p)\n",
327 (void *)fault_address, current->stack,
328 (char *)current->stack + THREAD_SIZE - 1);
329 die(message, regs, 0);
331 /* Be absolutely certain we don't return. */
337 /* Runs on IST stack */
338 dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code)
340 static const char str[] = "double fault";
341 struct task_struct *tsk = current;
342 #ifdef CONFIG_VMAP_STACK
346 #ifdef CONFIG_X86_ESPFIX64
347 extern unsigned char native_irq_return_iret[];
350 * If IRET takes a non-IST fault on the espfix64 stack, then we
351 * end up promoting it to a doublefault. In that case, modify
352 * the stack to make it look like we just entered the #GP
353 * handler from user space, similar to bad_iret.
355 * No need for ist_enter here because we don't use RCU.
357 if (((long)regs->sp >> PGDIR_SHIFT) == ESPFIX_PGD_ENTRY &&
358 regs->cs == __KERNEL_CS &&
359 regs->ip == (unsigned long)native_irq_return_iret)
361 struct pt_regs *normal_regs = task_pt_regs(current);
363 /* Fake a #GP(0) from userspace. */
364 memmove(&normal_regs->ip, (void *)regs->sp, 5*8);
365 normal_regs->orig_ax = 0; /* Missing (lost) #GP error code */
366 regs->ip = (unsigned long)general_protection;
367 regs->sp = (unsigned long)&normal_regs->orig_ax;
374 notify_die(DIE_TRAP, str, regs, error_code, X86_TRAP_DF, SIGSEGV);
376 tsk->thread.error_code = error_code;
377 tsk->thread.trap_nr = X86_TRAP_DF;
379 #ifdef CONFIG_VMAP_STACK
381 * If we overflow the stack into a guard page, the CPU will fail
382 * to deliver #PF and will send #DF instead. Similarly, if we
383 * take any non-IST exception while too close to the bottom of
384 * the stack, the processor will get a page fault while
385 * delivering the exception and will generate a double fault.
387 * According to the SDM (footnote in 6.15 under "Interrupt 14 -
388 * Page-Fault Exception (#PF):
390 * Processors update CR2 whenever a page fault is detected. If a
391 * second page fault occurs while an earlier page fault is being
392 * deliv- ered, the faulting linear address of the second fault will
393 * overwrite the contents of CR2 (replacing the previous
394 * address). These updates to CR2 occur even if the page fault
395 * results in a double fault or occurs during the delivery of a
398 * The logic below has a small possibility of incorrectly diagnosing
399 * some errors as stack overflows. For example, if the IDT or GDT
400 * gets corrupted such that #GP delivery fails due to a bad descriptor
401 * causing #GP and we hit this condition while CR2 coincidentally
402 * points to the stack guard page, we'll think we overflowed the
403 * stack. Given that we're going to panic one way or another
404 * if this happens, this isn't necessarily worth fixing.
406 * If necessary, we could improve the test by only diagnosing
407 * a stack overflow if the saved RSP points within 47 bytes of
408 * the bottom of the stack: if RSP == tsk_stack + 48 and we
409 * take an exception, the stack is already aligned and there
410 * will be enough room SS, RSP, RFLAGS, CS, RIP, and a
411 * possible error code, so a stack overflow would *not* double
412 * fault. With any less space left, exception delivery could
413 * fail, and, as a practical matter, we've overflowed the
414 * stack even if the actual trigger for the double fault was
418 if ((unsigned long)task_stack_page(tsk) - 1 - cr2 < PAGE_SIZE)
419 handle_stack_overflow("kernel stack overflow (double-fault)", regs, cr2);
422 #ifdef CONFIG_DOUBLEFAULT
423 df_debug(regs, error_code);
426 * This is always a kernel trap and never fixable (and thus must
430 die(str, regs, error_code);
434 dotraplinkage void do_bounds(struct pt_regs *regs, long error_code)
436 const struct mpx_bndcsr *bndcsr;
439 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
440 if (notify_die(DIE_TRAP, "bounds", regs, error_code,
441 X86_TRAP_BR, SIGSEGV) == NOTIFY_STOP)
443 cond_local_irq_enable(regs);
445 if (!user_mode(regs))
446 die("bounds", regs, error_code);
448 if (!cpu_feature_enabled(X86_FEATURE_MPX)) {
449 /* The exception is not from Intel MPX */
454 * We need to look at BNDSTATUS to resolve this exception.
455 * A NULL here might mean that it is in its 'init state',
456 * which is all zeros which indicates MPX was not
457 * responsible for the exception.
459 bndcsr = get_xsave_field_ptr(XFEATURE_MASK_BNDCSR);
463 trace_bounds_exception_mpx(bndcsr);
465 * The error code field of the BNDSTATUS register communicates status
466 * information of a bound range exception #BR or operation involving
469 switch (bndcsr->bndstatus & MPX_BNDSTA_ERROR_CODE) {
470 case 2: /* Bound directory has invalid entry. */
471 if (mpx_handle_bd_fault())
473 break; /* Success, it was handled */
474 case 1: /* Bound violation. */
475 info = mpx_generate_siginfo(regs);
478 * We failed to decode the MPX instruction. Act as if
479 * the exception was not caused by MPX.
484 * Success, we decoded the instruction and retrieved
485 * an 'info' containing the address being accessed
486 * which caused the exception. This information
487 * allows and application to possibly handle the
488 * #BR exception itself.
490 do_trap(X86_TRAP_BR, SIGSEGV, "bounds", regs, error_code, info);
493 case 0: /* No exception caused by Intel MPX operations. */
496 die("bounds", regs, error_code);
503 * This path out is for all the cases where we could not
504 * handle the exception in some way (like allocating a
505 * table or telling userspace about it. We will also end
506 * up here if the kernel has MPX turned off at compile
509 do_trap(X86_TRAP_BR, SIGSEGV, "bounds", regs, error_code, NULL);
513 do_general_protection(struct pt_regs *regs, long error_code)
515 struct task_struct *tsk;
517 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
518 cond_local_irq_enable(regs);
520 if (static_cpu_has(X86_FEATURE_UMIP)) {
521 if (user_mode(regs) && fixup_umip_exception(regs))
525 if (v8086_mode(regs)) {
527 handle_vm86_fault((struct kernel_vm86_regs *) regs, error_code);
532 if (!user_mode(regs)) {
533 if (fixup_exception(regs, X86_TRAP_GP))
536 tsk->thread.error_code = error_code;
537 tsk->thread.trap_nr = X86_TRAP_GP;
538 if (notify_die(DIE_GPF, "general protection fault", regs, error_code,
539 X86_TRAP_GP, SIGSEGV) != NOTIFY_STOP)
540 die("general protection fault", regs, error_code);
544 tsk->thread.error_code = error_code;
545 tsk->thread.trap_nr = X86_TRAP_GP;
547 if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) &&
548 printk_ratelimit()) {
549 pr_info("%s[%d] general protection ip:%lx sp:%lx error:%lx",
550 tsk->comm, task_pid_nr(tsk),
551 regs->ip, regs->sp, error_code);
552 print_vma_addr(KERN_CONT " in ", regs->ip);
556 force_sig_info(SIGSEGV, SEND_SIG_PRIV, tsk);
558 NOKPROBE_SYMBOL(do_general_protection);
560 /* May run on IST stack. */
561 dotraplinkage void notrace do_int3(struct pt_regs *regs, long error_code)
563 #ifdef CONFIG_DYNAMIC_FTRACE
565 * ftrace must be first, everything else may cause a recursive crash.
566 * See note by declaration of modifying_ftrace_code in ftrace.c
568 if (unlikely(atomic_read(&modifying_ftrace_code)) &&
569 ftrace_int3_handler(regs))
572 if (poke_int3_handler(regs))
576 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
577 #ifdef CONFIG_KGDB_LOW_LEVEL_TRAP
578 if (kgdb_ll_trap(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP,
579 SIGTRAP) == NOTIFY_STOP)
581 #endif /* CONFIG_KGDB_LOW_LEVEL_TRAP */
583 #ifdef CONFIG_KPROBES
584 if (kprobe_int3_handler(regs))
588 if (notify_die(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP,
589 SIGTRAP) == NOTIFY_STOP)
593 * Let others (NMI) know that the debug stack is in use
594 * as we may switch to the interrupt stack.
596 debug_stack_usage_inc();
597 cond_local_irq_enable(regs);
598 do_trap(X86_TRAP_BP, SIGTRAP, "int3", regs, error_code, NULL);
599 cond_local_irq_disable(regs);
600 debug_stack_usage_dec();
604 NOKPROBE_SYMBOL(do_int3);
608 * Help handler running on IST stack to switch off the IST stack if the
609 * interrupted code was in user mode. The actual stack switch is done in
612 asmlinkage __visible notrace struct pt_regs *sync_regs(struct pt_regs *eregs)
614 struct pt_regs *regs = task_pt_regs(current);
618 NOKPROBE_SYMBOL(sync_regs);
620 struct bad_iret_stack {
621 void *error_entry_ret;
625 asmlinkage __visible notrace
626 struct bad_iret_stack *fixup_bad_iret(struct bad_iret_stack *s)
629 * This is called from entry_64.S early in handling a fault
630 * caused by a bad iret to user mode. To handle the fault
631 * correctly, we want move our stack frame to task_pt_regs
632 * and we want to pretend that the exception came from the
635 struct bad_iret_stack *new_stack =
636 container_of(task_pt_regs(current),
637 struct bad_iret_stack, regs);
639 /* Copy the IRET target to the new stack. */
640 memmove(&new_stack->regs.ip, (void *)s->regs.sp, 5*8);
642 /* Copy the remainder of the stack from the current stack. */
643 memmove(new_stack, s, offsetof(struct bad_iret_stack, regs.ip));
645 BUG_ON(!user_mode(&new_stack->regs));
648 NOKPROBE_SYMBOL(fixup_bad_iret);
651 static bool is_sysenter_singlestep(struct pt_regs *regs)
654 * We don't try for precision here. If we're anywhere in the region of
655 * code that can be single-stepped in the SYSENTER entry path, then
656 * assume that this is a useless single-step trap due to SYSENTER
657 * being invoked with TF set. (We don't know in advance exactly
658 * which instructions will be hit because BTF could plausibly
662 return (regs->ip - (unsigned long)__begin_SYSENTER_singlestep_region) <
663 (unsigned long)__end_SYSENTER_singlestep_region -
664 (unsigned long)__begin_SYSENTER_singlestep_region;
665 #elif defined(CONFIG_IA32_EMULATION)
666 return (regs->ip - (unsigned long)entry_SYSENTER_compat) <
667 (unsigned long)__end_entry_SYSENTER_compat -
668 (unsigned long)entry_SYSENTER_compat;
675 * Our handling of the processor debug registers is non-trivial.
676 * We do not clear them on entry and exit from the kernel. Therefore
677 * it is possible to get a watchpoint trap here from inside the kernel.
678 * However, the code in ./ptrace.c has ensured that the user can
679 * only set watchpoints on userspace addresses. Therefore the in-kernel
680 * watchpoint trap can only occur in code which is reading/writing
681 * from user space. Such code must not hold kernel locks (since it
682 * can equally take a page fault), therefore it is safe to call
683 * force_sig_info even though that claims and releases locks.
685 * Code in ./signal.c ensures that the debug control register
686 * is restored before we deliver any signal, and therefore that
687 * user code runs with the correct debug control register even though
690 * Being careful here means that we don't have to be as careful in a
691 * lot of more complicated places (task switching can be a bit lazy
692 * about restoring all the debug state, and ptrace doesn't have to
693 * find every occurrence of the TF bit that could be saved away even
696 * May run on IST stack.
698 dotraplinkage void do_debug(struct pt_regs *regs, long error_code)
700 struct task_struct *tsk = current;
707 get_debugreg(dr6, 6);
709 * The Intel SDM says:
711 * Certain debug exceptions may clear bits 0-3. The remaining
712 * contents of the DR6 register are never cleared by the
713 * processor. To avoid confusion in identifying debug
714 * exceptions, debug handlers should clear the register before
715 * returning to the interrupted task.
717 * Keep it simple: clear DR6 immediately.
721 /* Filter out all the reserved bits which are preset to 1 */
722 dr6 &= ~DR6_RESERVED;
725 * The SDM says "The processor clears the BTF flag when it
726 * generates a debug exception." Clear TIF_BLOCKSTEP to keep
727 * TIF_BLOCKSTEP in sync with the hardware BTF flag.
729 clear_tsk_thread_flag(tsk, TIF_BLOCKSTEP);
731 if (unlikely(!user_mode(regs) && (dr6 & DR_STEP) &&
732 is_sysenter_singlestep(regs))) {
737 * else we might have gotten a single-step trap and hit a
738 * watchpoint at the same time, in which case we should fall
739 * through and handle the watchpoint.
744 * If dr6 has no reason to give us about the origin of this trap,
745 * then it's very likely the result of an icebp/int01 trap.
746 * User wants a sigtrap for that.
748 if (!dr6 && user_mode(regs))
751 /* Store the virtualized DR6 value */
752 tsk->thread.debugreg6 = dr6;
754 #ifdef CONFIG_KPROBES
755 if (kprobe_debug_handler(regs))
759 if (notify_die(DIE_DEBUG, "debug", regs, (long)&dr6, error_code,
760 SIGTRAP) == NOTIFY_STOP)
764 * Let others (NMI) know that the debug stack is in use
765 * as we may switch to the interrupt stack.
767 debug_stack_usage_inc();
769 /* It's safe to allow irq's after DR6 has been saved */
770 cond_local_irq_enable(regs);
772 if (v8086_mode(regs)) {
773 handle_vm86_trap((struct kernel_vm86_regs *) regs, error_code,
775 cond_local_irq_disable(regs);
776 debug_stack_usage_dec();
780 if (WARN_ON_ONCE((dr6 & DR_STEP) && !user_mode(regs))) {
782 * Historical junk that used to handle SYSENTER single-stepping.
783 * This should be unreachable now. If we survive for a while
784 * without anyone hitting this warning, we'll turn this into
787 tsk->thread.debugreg6 &= ~DR_STEP;
788 set_tsk_thread_flag(tsk, TIF_SINGLESTEP);
789 regs->flags &= ~X86_EFLAGS_TF;
791 si_code = get_si_code(tsk->thread.debugreg6);
792 if (tsk->thread.debugreg6 & (DR_STEP | DR_TRAP_BITS) || user_icebp)
793 send_sigtrap(tsk, regs, error_code, si_code);
794 cond_local_irq_disable(regs);
795 debug_stack_usage_dec();
798 #if defined(CONFIG_X86_32)
800 * This is the most likely code path that involves non-trivial use
801 * of the SYSENTER stack. Check that we haven't overrun it.
803 WARN(this_cpu_read(cpu_tss.SYSENTER_stack_canary) != STACK_END_MAGIC,
804 "Overran or corrupted SYSENTER stack\n");
808 NOKPROBE_SYMBOL(do_debug);
811 * Note that we play around with the 'TS' bit in an attempt to get
812 * the correct behaviour even in the presence of the asynchronous
815 static void math_error(struct pt_regs *regs, int error_code, int trapnr)
817 struct task_struct *task = current;
818 struct fpu *fpu = &task->thread.fpu;
820 char *str = (trapnr == X86_TRAP_MF) ? "fpu exception" :
823 if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, SIGFPE) == NOTIFY_STOP)
825 cond_local_irq_enable(regs);
827 if (!user_mode(regs)) {
828 if (!fixup_exception(regs, trapnr)) {
829 task->thread.error_code = error_code;
830 task->thread.trap_nr = trapnr;
831 die(str, regs, error_code);
837 * Save the info for the exception handler and clear the error.
841 task->thread.trap_nr = trapnr;
842 task->thread.error_code = error_code;
843 info.si_signo = SIGFPE;
845 info.si_addr = (void __user *)uprobe_get_trap_addr(regs);
847 info.si_code = fpu__exception_code(fpu, trapnr);
849 /* Retry when we get spurious exceptions: */
853 force_sig_info(SIGFPE, &info, task);
856 dotraplinkage void do_coprocessor_error(struct pt_regs *regs, long error_code)
858 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
859 math_error(regs, error_code, X86_TRAP_MF);
863 do_simd_coprocessor_error(struct pt_regs *regs, long error_code)
865 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
866 math_error(regs, error_code, X86_TRAP_XF);
870 do_spurious_interrupt_bug(struct pt_regs *regs, long error_code)
872 cond_local_irq_enable(regs);
876 do_device_not_available(struct pt_regs *regs, long error_code)
880 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
882 #ifdef CONFIG_MATH_EMULATION
883 if (!boot_cpu_has(X86_FEATURE_FPU) && (read_cr0() & X86_CR0_EM)) {
884 struct math_emu_info info = { };
886 cond_local_irq_enable(regs);
894 /* This should not happen. */
896 if (WARN(cr0 & X86_CR0_TS, "CR0.TS was set")) {
897 /* Try to fix it up and carry on. */
898 write_cr0(cr0 & ~X86_CR0_TS);
901 * Something terrible happened, and we're better off trying
902 * to kill the task than getting stuck in a never-ending
903 * loop of #NM faults.
905 die("unexpected #NM exception", regs, error_code);
908 NOKPROBE_SYMBOL(do_device_not_available);
911 dotraplinkage void do_iret_error(struct pt_regs *regs, long error_code)
915 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
918 info.si_signo = SIGILL;
920 info.si_code = ILL_BADSTK;
922 if (notify_die(DIE_TRAP, "iret exception", regs, error_code,
923 X86_TRAP_IRET, SIGILL) != NOTIFY_STOP) {
924 do_trap(X86_TRAP_IRET, SIGILL, "iret exception", regs, error_code,
930 void __init trap_init(void)
935 * Set the IDT descriptor to a fixed read-only location, so that the
936 * "sidt" instruction will not leak the location of the kernel, and
937 * to defend the IDT against arbitrary memory write vulnerabilities.
938 * It will be reloaded in cpu_init() */
939 __set_fixmap(FIX_RO_IDT, __pa_symbol(idt_table), PAGE_KERNEL_RO);
940 idt_descr.address = fix_to_virt(FIX_RO_IDT);
943 * Should be a barrier for any external CPU state:
947 idt_setup_ist_traps();
949 x86_init.irqs.trap_init();
951 idt_setup_debugidt_traps();