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(!on_thread_stack());
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 int is_valid_bugaddr(unsigned long addr
)
175 if (addr
< TASK_SIZE_MAX
)
178 if (probe_kernel_address((unsigned short *)addr
, ud
))
181 return ud
== INSN_UD0
|| ud
== INSN_UD2
;
184 int fixup_bug(struct pt_regs
*regs
, int trapnr
)
186 if (trapnr
!= X86_TRAP_UD
)
189 switch (report_bug(regs
->ip
, regs
)) {
190 case BUG_TRAP_TYPE_NONE
:
191 case BUG_TRAP_TYPE_BUG
:
194 case BUG_TRAP_TYPE_WARN
:
202 static nokprobe_inline
int
203 do_trap_no_signal(struct task_struct
*tsk
, int trapnr
, char *str
,
204 struct pt_regs
*regs
, long error_code
)
206 if (v8086_mode(regs
)) {
208 * Traps 0, 1, 3, 4, and 5 should be forwarded to vm86.
209 * On nmi (interrupt 2), do_trap should not be called.
211 if (trapnr
< X86_TRAP_UD
) {
212 if (!handle_vm86_trap((struct kernel_vm86_regs
*) regs
,
219 if (!user_mode(regs
)) {
220 if (fixup_exception(regs
, trapnr
))
223 tsk
->thread
.error_code
= error_code
;
224 tsk
->thread
.trap_nr
= trapnr
;
225 die(str
, regs
, error_code
);
231 static siginfo_t
*fill_trap_info(struct pt_regs
*regs
, int signr
, int trapnr
,
234 unsigned long siaddr
;
239 return SEND_SIG_PRIV
;
243 siaddr
= uprobe_get_trap_addr(regs
);
247 siaddr
= uprobe_get_trap_addr(regs
);
255 info
->si_signo
= signr
;
257 info
->si_code
= sicode
;
258 info
->si_addr
= (void __user
*)siaddr
;
263 do_trap(int trapnr
, int signr
, char *str
, struct pt_regs
*regs
,
264 long error_code
, siginfo_t
*info
)
266 struct task_struct
*tsk
= current
;
269 if (!do_trap_no_signal(tsk
, trapnr
, str
, regs
, error_code
))
272 * We want error_code and trap_nr set for userspace faults and
273 * kernelspace faults which result in die(), but not
274 * kernelspace faults which are fixed up. die() gives the
275 * process no chance to handle the signal and notice the
276 * kernel fault information, so that won't result in polluting
277 * the information about previously queued, but not yet
278 * delivered, faults. See also do_general_protection below.
280 tsk
->thread
.error_code
= error_code
;
281 tsk
->thread
.trap_nr
= trapnr
;
283 if (show_unhandled_signals
&& unhandled_signal(tsk
, signr
) &&
284 printk_ratelimit()) {
285 pr_info("%s[%d] trap %s ip:%lx sp:%lx error:%lx",
286 tsk
->comm
, tsk
->pid
, str
,
287 regs
->ip
, regs
->sp
, error_code
);
288 print_vma_addr(KERN_CONT
" in ", regs
->ip
);
292 force_sig_info(signr
, info
?: SEND_SIG_PRIV
, tsk
);
294 NOKPROBE_SYMBOL(do_trap
);
296 static void do_error_trap(struct pt_regs
*regs
, long error_code
, char *str
,
297 unsigned long trapnr
, int signr
)
301 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
304 * WARN*()s end up here; fix them up before we call the
307 if (!user_mode(regs
) && fixup_bug(regs
, trapnr
))
310 if (notify_die(DIE_TRAP
, str
, regs
, error_code
, trapnr
, signr
) !=
312 cond_local_irq_enable(regs
);
313 do_trap(trapnr
, signr
, str
, regs
, error_code
,
314 fill_trap_info(regs
, signr
, trapnr
, &info
));
318 #define DO_ERROR(trapnr, signr, str, name) \
319 dotraplinkage void do_##name(struct pt_regs *regs, long error_code) \
321 do_error_trap(regs, error_code, str, trapnr, signr); \
324 DO_ERROR(X86_TRAP_DE
, SIGFPE
, "divide error", divide_error
)
325 DO_ERROR(X86_TRAP_OF
, SIGSEGV
, "overflow", overflow
)
326 DO_ERROR(X86_TRAP_UD
, SIGILL
, "invalid opcode", invalid_op
)
327 DO_ERROR(X86_TRAP_OLD_MF
, SIGFPE
, "coprocessor segment overrun",coprocessor_segment_overrun
)
328 DO_ERROR(X86_TRAP_TS
, SIGSEGV
, "invalid TSS", invalid_TSS
)
329 DO_ERROR(X86_TRAP_NP
, SIGBUS
, "segment not present", segment_not_present
)
330 DO_ERROR(X86_TRAP_SS
, SIGBUS
, "stack segment", stack_segment
)
331 DO_ERROR(X86_TRAP_AC
, SIGBUS
, "alignment check", alignment_check
)
333 #ifdef CONFIG_VMAP_STACK
334 __visible
void __noreturn
handle_stack_overflow(const char *message
,
335 struct pt_regs
*regs
,
336 unsigned long fault_address
)
338 printk(KERN_EMERG
"BUG: stack guard page was hit at %p (stack is %p..%p)\n",
339 (void *)fault_address
, current
->stack
,
340 (char *)current
->stack
+ THREAD_SIZE
- 1);
341 die(message
, regs
, 0);
343 /* Be absolutely certain we don't return. */
349 /* Runs on IST stack */
350 dotraplinkage
void do_double_fault(struct pt_regs
*regs
, long error_code
)
352 static const char str
[] = "double fault";
353 struct task_struct
*tsk
= current
;
354 #ifdef CONFIG_VMAP_STACK
358 #ifdef CONFIG_X86_ESPFIX64
359 extern unsigned char native_irq_return_iret
[];
362 * If IRET takes a non-IST fault on the espfix64 stack, then we
363 * end up promoting it to a doublefault. In that case, modify
364 * the stack to make it look like we just entered the #GP
365 * handler from user space, similar to bad_iret.
367 * No need for ist_enter here because we don't use RCU.
369 if (((long)regs
->sp
>> PGDIR_SHIFT
) == ESPFIX_PGD_ENTRY
&&
370 regs
->cs
== __KERNEL_CS
&&
371 regs
->ip
== (unsigned long)native_irq_return_iret
)
373 struct pt_regs
*normal_regs
= task_pt_regs(current
);
375 /* Fake a #GP(0) from userspace. */
376 memmove(&normal_regs
->ip
, (void *)regs
->sp
, 5*8);
377 normal_regs
->orig_ax
= 0; /* Missing (lost) #GP error code */
378 regs
->ip
= (unsigned long)general_protection
;
379 regs
->sp
= (unsigned long)&normal_regs
->orig_ax
;
386 notify_die(DIE_TRAP
, str
, regs
, error_code
, X86_TRAP_DF
, SIGSEGV
);
388 tsk
->thread
.error_code
= error_code
;
389 tsk
->thread
.trap_nr
= X86_TRAP_DF
;
391 #ifdef CONFIG_VMAP_STACK
393 * If we overflow the stack into a guard page, the CPU will fail
394 * to deliver #PF and will send #DF instead. Similarly, if we
395 * take any non-IST exception while too close to the bottom of
396 * the stack, the processor will get a page fault while
397 * delivering the exception and will generate a double fault.
399 * According to the SDM (footnote in 6.15 under "Interrupt 14 -
400 * Page-Fault Exception (#PF):
402 * Processors update CR2 whenever a page fault is detected. If a
403 * second page fault occurs while an earlier page fault is being
404 * deliv- ered, the faulting linear address of the second fault will
405 * overwrite the contents of CR2 (replacing the previous
406 * address). These updates to CR2 occur even if the page fault
407 * results in a double fault or occurs during the delivery of a
410 * The logic below has a small possibility of incorrectly diagnosing
411 * some errors as stack overflows. For example, if the IDT or GDT
412 * gets corrupted such that #GP delivery fails due to a bad descriptor
413 * causing #GP and we hit this condition while CR2 coincidentally
414 * points to the stack guard page, we'll think we overflowed the
415 * stack. Given that we're going to panic one way or another
416 * if this happens, this isn't necessarily worth fixing.
418 * If necessary, we could improve the test by only diagnosing
419 * a stack overflow if the saved RSP points within 47 bytes of
420 * the bottom of the stack: if RSP == tsk_stack + 48 and we
421 * take an exception, the stack is already aligned and there
422 * will be enough room SS, RSP, RFLAGS, CS, RIP, and a
423 * possible error code, so a stack overflow would *not* double
424 * fault. With any less space left, exception delivery could
425 * fail, and, as a practical matter, we've overflowed the
426 * stack even if the actual trigger for the double fault was
430 if ((unsigned long)task_stack_page(tsk
) - 1 - cr2
< PAGE_SIZE
)
431 handle_stack_overflow("kernel stack overflow (double-fault)", regs
, cr2
);
434 #ifdef CONFIG_DOUBLEFAULT
435 df_debug(regs
, error_code
);
438 * This is always a kernel trap and never fixable (and thus must
442 die(str
, regs
, error_code
);
446 dotraplinkage
void do_bounds(struct pt_regs
*regs
, long error_code
)
448 const struct mpx_bndcsr
*bndcsr
;
451 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
452 if (notify_die(DIE_TRAP
, "bounds", regs
, error_code
,
453 X86_TRAP_BR
, SIGSEGV
) == NOTIFY_STOP
)
455 cond_local_irq_enable(regs
);
457 if (!user_mode(regs
))
458 die("bounds", regs
, error_code
);
460 if (!cpu_feature_enabled(X86_FEATURE_MPX
)) {
461 /* The exception is not from Intel MPX */
466 * We need to look at BNDSTATUS to resolve this exception.
467 * A NULL here might mean that it is in its 'init state',
468 * which is all zeros which indicates MPX was not
469 * responsible for the exception.
471 bndcsr
= get_xsave_field_ptr(XFEATURE_MASK_BNDCSR
);
475 trace_bounds_exception_mpx(bndcsr
);
477 * The error code field of the BNDSTATUS register communicates status
478 * information of a bound range exception #BR or operation involving
481 switch (bndcsr
->bndstatus
& MPX_BNDSTA_ERROR_CODE
) {
482 case 2: /* Bound directory has invalid entry. */
483 if (mpx_handle_bd_fault())
485 break; /* Success, it was handled */
486 case 1: /* Bound violation. */
487 info
= mpx_generate_siginfo(regs
);
490 * We failed to decode the MPX instruction. Act as if
491 * the exception was not caused by MPX.
496 * Success, we decoded the instruction and retrieved
497 * an 'info' containing the address being accessed
498 * which caused the exception. This information
499 * allows and application to possibly handle the
500 * #BR exception itself.
502 do_trap(X86_TRAP_BR
, SIGSEGV
, "bounds", regs
, error_code
, info
);
505 case 0: /* No exception caused by Intel MPX operations. */
508 die("bounds", regs
, error_code
);
515 * This path out is for all the cases where we could not
516 * handle the exception in some way (like allocating a
517 * table or telling userspace about it. We will also end
518 * up here if the kernel has MPX turned off at compile
521 do_trap(X86_TRAP_BR
, SIGSEGV
, "bounds", regs
, error_code
, NULL
);
525 do_general_protection(struct pt_regs
*regs
, long error_code
)
527 struct task_struct
*tsk
;
529 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
530 cond_local_irq_enable(regs
);
532 if (v8086_mode(regs
)) {
534 handle_vm86_fault((struct kernel_vm86_regs
*) regs
, error_code
);
539 if (!user_mode(regs
)) {
540 if (fixup_exception(regs
, X86_TRAP_GP
))
543 tsk
->thread
.error_code
= error_code
;
544 tsk
->thread
.trap_nr
= X86_TRAP_GP
;
545 if (notify_die(DIE_GPF
, "general protection fault", regs
, error_code
,
546 X86_TRAP_GP
, SIGSEGV
) != NOTIFY_STOP
)
547 die("general protection fault", regs
, error_code
);
551 tsk
->thread
.error_code
= error_code
;
552 tsk
->thread
.trap_nr
= X86_TRAP_GP
;
554 if (show_unhandled_signals
&& unhandled_signal(tsk
, SIGSEGV
) &&
555 printk_ratelimit()) {
556 pr_info("%s[%d] general protection ip:%lx sp:%lx error:%lx",
557 tsk
->comm
, task_pid_nr(tsk
),
558 regs
->ip
, regs
->sp
, error_code
);
559 print_vma_addr(KERN_CONT
" in ", regs
->ip
);
563 force_sig_info(SIGSEGV
, SEND_SIG_PRIV
, tsk
);
565 NOKPROBE_SYMBOL(do_general_protection
);
567 /* May run on IST stack. */
568 dotraplinkage
void notrace
do_int3(struct pt_regs
*regs
, long error_code
)
570 #ifdef CONFIG_DYNAMIC_FTRACE
572 * ftrace must be first, everything else may cause a recursive crash.
573 * See note by declaration of modifying_ftrace_code in ftrace.c
575 if (unlikely(atomic_read(&modifying_ftrace_code
)) &&
576 ftrace_int3_handler(regs
))
579 if (poke_int3_handler(regs
))
583 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
584 #ifdef CONFIG_KGDB_LOW_LEVEL_TRAP
585 if (kgdb_ll_trap(DIE_INT3
, "int3", regs
, error_code
, X86_TRAP_BP
,
586 SIGTRAP
) == NOTIFY_STOP
)
588 #endif /* CONFIG_KGDB_LOW_LEVEL_TRAP */
590 #ifdef CONFIG_KPROBES
591 if (kprobe_int3_handler(regs
))
595 if (notify_die(DIE_INT3
, "int3", regs
, error_code
, X86_TRAP_BP
,
596 SIGTRAP
) == NOTIFY_STOP
)
600 * Let others (NMI) know that the debug stack is in use
601 * as we may switch to the interrupt stack.
603 debug_stack_usage_inc();
604 cond_local_irq_enable(regs
);
605 do_trap(X86_TRAP_BP
, SIGTRAP
, "int3", regs
, error_code
, NULL
);
606 cond_local_irq_disable(regs
);
607 debug_stack_usage_dec();
611 NOKPROBE_SYMBOL(do_int3
);
615 * Help handler running on IST stack to switch off the IST stack if the
616 * interrupted code was in user mode. The actual stack switch is done in
619 asmlinkage __visible notrace
struct pt_regs
*sync_regs(struct pt_regs
*eregs
)
621 struct pt_regs
*regs
= task_pt_regs(current
);
625 NOKPROBE_SYMBOL(sync_regs
);
627 struct bad_iret_stack
{
628 void *error_entry_ret
;
632 asmlinkage __visible notrace
633 struct bad_iret_stack
*fixup_bad_iret(struct bad_iret_stack
*s
)
636 * This is called from entry_64.S early in handling a fault
637 * caused by a bad iret to user mode. To handle the fault
638 * correctly, we want move our stack frame to task_pt_regs
639 * and we want to pretend that the exception came from the
642 struct bad_iret_stack
*new_stack
=
643 container_of(task_pt_regs(current
),
644 struct bad_iret_stack
, regs
);
646 /* Copy the IRET target to the new stack. */
647 memmove(&new_stack
->regs
.ip
, (void *)s
->regs
.sp
, 5*8);
649 /* Copy the remainder of the stack from the current stack. */
650 memmove(new_stack
, s
, offsetof(struct bad_iret_stack
, regs
.ip
));
652 BUG_ON(!user_mode(&new_stack
->regs
));
655 NOKPROBE_SYMBOL(fixup_bad_iret
);
658 static bool is_sysenter_singlestep(struct pt_regs
*regs
)
661 * We don't try for precision here. If we're anywhere in the region of
662 * code that can be single-stepped in the SYSENTER entry path, then
663 * assume that this is a useless single-step trap due to SYSENTER
664 * being invoked with TF set. (We don't know in advance exactly
665 * which instructions will be hit because BTF could plausibly
669 return (regs
->ip
- (unsigned long)__begin_SYSENTER_singlestep_region
) <
670 (unsigned long)__end_SYSENTER_singlestep_region
-
671 (unsigned long)__begin_SYSENTER_singlestep_region
;
672 #elif defined(CONFIG_IA32_EMULATION)
673 return (regs
->ip
- (unsigned long)entry_SYSENTER_compat
) <
674 (unsigned long)__end_entry_SYSENTER_compat
-
675 (unsigned long)entry_SYSENTER_compat
;
682 * Our handling of the processor debug registers is non-trivial.
683 * We do not clear them on entry and exit from the kernel. Therefore
684 * it is possible to get a watchpoint trap here from inside the kernel.
685 * However, the code in ./ptrace.c has ensured that the user can
686 * only set watchpoints on userspace addresses. Therefore the in-kernel
687 * watchpoint trap can only occur in code which is reading/writing
688 * from user space. Such code must not hold kernel locks (since it
689 * can equally take a page fault), therefore it is safe to call
690 * force_sig_info even though that claims and releases locks.
692 * Code in ./signal.c ensures that the debug control register
693 * is restored before we deliver any signal, and therefore that
694 * user code runs with the correct debug control register even though
697 * Being careful here means that we don't have to be as careful in a
698 * lot of more complicated places (task switching can be a bit lazy
699 * about restoring all the debug state, and ptrace doesn't have to
700 * find every occurrence of the TF bit that could be saved away even
703 * May run on IST stack.
705 dotraplinkage
void do_debug(struct pt_regs
*regs
, long error_code
)
707 struct task_struct
*tsk
= current
;
714 get_debugreg(dr6
, 6);
716 * The Intel SDM says:
718 * Certain debug exceptions may clear bits 0-3. The remaining
719 * contents of the DR6 register are never cleared by the
720 * processor. To avoid confusion in identifying debug
721 * exceptions, debug handlers should clear the register before
722 * returning to the interrupted task.
724 * Keep it simple: clear DR6 immediately.
728 /* Filter out all the reserved bits which are preset to 1 */
729 dr6
&= ~DR6_RESERVED
;
732 * The SDM says "The processor clears the BTF flag when it
733 * generates a debug exception." Clear TIF_BLOCKSTEP to keep
734 * TIF_BLOCKSTEP in sync with the hardware BTF flag.
736 clear_tsk_thread_flag(tsk
, TIF_BLOCKSTEP
);
738 if (unlikely(!user_mode(regs
) && (dr6
& DR_STEP
) &&
739 is_sysenter_singlestep(regs
))) {
744 * else we might have gotten a single-step trap and hit a
745 * watchpoint at the same time, in which case we should fall
746 * through and handle the watchpoint.
751 * If dr6 has no reason to give us about the origin of this trap,
752 * then it's very likely the result of an icebp/int01 trap.
753 * User wants a sigtrap for that.
755 if (!dr6
&& user_mode(regs
))
758 /* Catch kmemcheck conditions! */
759 if ((dr6
& DR_STEP
) && kmemcheck_trap(regs
))
762 /* Store the virtualized DR6 value */
763 tsk
->thread
.debugreg6
= dr6
;
765 #ifdef CONFIG_KPROBES
766 if (kprobe_debug_handler(regs
))
770 if (notify_die(DIE_DEBUG
, "debug", regs
, (long)&dr6
, error_code
,
771 SIGTRAP
) == NOTIFY_STOP
)
775 * Let others (NMI) know that the debug stack is in use
776 * as we may switch to the interrupt stack.
778 debug_stack_usage_inc();
780 /* It's safe to allow irq's after DR6 has been saved */
781 cond_local_irq_enable(regs
);
783 if (v8086_mode(regs
)) {
784 handle_vm86_trap((struct kernel_vm86_regs
*) regs
, error_code
,
786 cond_local_irq_disable(regs
);
787 debug_stack_usage_dec();
791 if (WARN_ON_ONCE((dr6
& DR_STEP
) && !user_mode(regs
))) {
793 * Historical junk that used to handle SYSENTER single-stepping.
794 * This should be unreachable now. If we survive for a while
795 * without anyone hitting this warning, we'll turn this into
798 tsk
->thread
.debugreg6
&= ~DR_STEP
;
799 set_tsk_thread_flag(tsk
, TIF_SINGLESTEP
);
800 regs
->flags
&= ~X86_EFLAGS_TF
;
802 si_code
= get_si_code(tsk
->thread
.debugreg6
);
803 if (tsk
->thread
.debugreg6
& (DR_STEP
| DR_TRAP_BITS
) || user_icebp
)
804 send_sigtrap(tsk
, regs
, error_code
, si_code
);
805 cond_local_irq_disable(regs
);
806 debug_stack_usage_dec();
809 #if defined(CONFIG_X86_32)
811 * This is the most likely code path that involves non-trivial use
812 * of the SYSENTER stack. Check that we haven't overrun it.
814 WARN(this_cpu_read(cpu_tss
.SYSENTER_stack_canary
) != STACK_END_MAGIC
,
815 "Overran or corrupted SYSENTER stack\n");
819 NOKPROBE_SYMBOL(do_debug
);
822 * Note that we play around with the 'TS' bit in an attempt to get
823 * the correct behaviour even in the presence of the asynchronous
826 static void math_error(struct pt_regs
*regs
, int error_code
, int trapnr
)
828 struct task_struct
*task
= current
;
829 struct fpu
*fpu
= &task
->thread
.fpu
;
831 char *str
= (trapnr
== X86_TRAP_MF
) ? "fpu exception" :
834 if (notify_die(DIE_TRAP
, str
, regs
, error_code
, trapnr
, SIGFPE
) == NOTIFY_STOP
)
836 cond_local_irq_enable(regs
);
838 if (!user_mode(regs
)) {
839 if (!fixup_exception(regs
, trapnr
)) {
840 task
->thread
.error_code
= error_code
;
841 task
->thread
.trap_nr
= trapnr
;
842 die(str
, regs
, error_code
);
848 * Save the info for the exception handler and clear the error.
852 task
->thread
.trap_nr
= trapnr
;
853 task
->thread
.error_code
= error_code
;
854 info
.si_signo
= SIGFPE
;
856 info
.si_addr
= (void __user
*)uprobe_get_trap_addr(regs
);
858 info
.si_code
= fpu__exception_code(fpu
, trapnr
);
860 /* Retry when we get spurious exceptions: */
864 force_sig_info(SIGFPE
, &info
, task
);
867 dotraplinkage
void do_coprocessor_error(struct pt_regs
*regs
, long error_code
)
869 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
870 math_error(regs
, error_code
, X86_TRAP_MF
);
874 do_simd_coprocessor_error(struct pt_regs
*regs
, long error_code
)
876 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
877 math_error(regs
, error_code
, X86_TRAP_XF
);
881 do_spurious_interrupt_bug(struct pt_regs
*regs
, long error_code
)
883 cond_local_irq_enable(regs
);
887 do_device_not_available(struct pt_regs
*regs
, long error_code
)
891 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
893 #ifdef CONFIG_MATH_EMULATION
894 if (!boot_cpu_has(X86_FEATURE_FPU
) && (read_cr0() & X86_CR0_EM
)) {
895 struct math_emu_info info
= { };
897 cond_local_irq_enable(regs
);
905 /* This should not happen. */
907 if (WARN(cr0
& X86_CR0_TS
, "CR0.TS was set")) {
908 /* Try to fix it up and carry on. */
909 write_cr0(cr0
& ~X86_CR0_TS
);
912 * Something terrible happened, and we're better off trying
913 * to kill the task than getting stuck in a never-ending
914 * loop of #NM faults.
916 die("unexpected #NM exception", regs
, error_code
);
919 NOKPROBE_SYMBOL(do_device_not_available
);
922 dotraplinkage
void do_iret_error(struct pt_regs
*regs
, long error_code
)
926 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
929 info
.si_signo
= SIGILL
;
931 info
.si_code
= ILL_BADSTK
;
933 if (notify_die(DIE_TRAP
, "iret exception", regs
, error_code
,
934 X86_TRAP_IRET
, SIGILL
) != NOTIFY_STOP
) {
935 do_trap(X86_TRAP_IRET
, SIGILL
, "iret exception", regs
, error_code
,
941 /* Set of traps needed for early debugging. */
942 void __init
early_trap_init(void)
945 * Don't use IST to set DEBUG_STACK as it doesn't work until TSS
946 * is ready in cpu_init() <-- trap_init(). Before trap_init(),
947 * CPU runs at ring 0 so it is impossible to hit an invalid
948 * stack. Using the original stack works well enough at this
949 * early stage. DEBUG_STACK will be equipped after cpu_init() in
952 * We don't need to set trace_idt_table like set_intr_gate(),
953 * since we don't have trace_debug and it will be reset to
954 * 'debug' in trap_init() by set_intr_gate_ist().
956 set_intr_gate_notrace(X86_TRAP_DB
, debug
);
957 /* int3 can be called from all */
958 set_system_intr_gate(X86_TRAP_BP
, &int3
);
960 set_intr_gate(X86_TRAP_PF
, page_fault
);
962 load_idt(&idt_descr
);
965 void __init
early_trap_pf_init(void)
968 set_intr_gate(X86_TRAP_PF
, page_fault
);
972 void __init
trap_init(void)
977 void __iomem
*p
= early_ioremap(0x0FFFD9, 4);
979 if (readl(p
) == 'E' + ('I'<<8) + ('S'<<16) + ('A'<<24))
984 set_intr_gate(X86_TRAP_DE
, divide_error
);
985 set_intr_gate_ist(X86_TRAP_NMI
, &nmi
, NMI_STACK
);
986 /* int4 can be called from all */
987 set_system_intr_gate(X86_TRAP_OF
, &overflow
);
988 set_intr_gate(X86_TRAP_BR
, bounds
);
989 set_intr_gate(X86_TRAP_UD
, invalid_op
);
990 set_intr_gate(X86_TRAP_NM
, device_not_available
);
992 set_task_gate(X86_TRAP_DF
, GDT_ENTRY_DOUBLEFAULT_TSS
);
994 set_intr_gate_ist(X86_TRAP_DF
, &double_fault
, DOUBLEFAULT_STACK
);
996 set_intr_gate(X86_TRAP_OLD_MF
, coprocessor_segment_overrun
);
997 set_intr_gate(X86_TRAP_TS
, invalid_TSS
);
998 set_intr_gate(X86_TRAP_NP
, segment_not_present
);
999 set_intr_gate(X86_TRAP_SS
, stack_segment
);
1000 set_intr_gate(X86_TRAP_GP
, general_protection
);
1001 set_intr_gate(X86_TRAP_SPURIOUS
, spurious_interrupt_bug
);
1002 set_intr_gate(X86_TRAP_MF
, coprocessor_error
);
1003 set_intr_gate(X86_TRAP_AC
, alignment_check
);
1004 #ifdef CONFIG_X86_MCE
1005 set_intr_gate_ist(X86_TRAP_MC
, &machine_check
, MCE_STACK
);
1007 set_intr_gate(X86_TRAP_XF
, simd_coprocessor_error
);
1009 /* Reserve all the builtin and the syscall vector: */
1010 for (i
= 0; i
< FIRST_EXTERNAL_VECTOR
; i
++)
1011 set_bit(i
, used_vectors
);
1013 #ifdef CONFIG_IA32_EMULATION
1014 set_system_intr_gate(IA32_SYSCALL_VECTOR
, entry_INT80_compat
);
1015 set_bit(IA32_SYSCALL_VECTOR
, used_vectors
);
1018 #ifdef CONFIG_X86_32
1019 set_system_intr_gate(IA32_SYSCALL_VECTOR
, entry_INT80_32
);
1020 set_bit(IA32_SYSCALL_VECTOR
, used_vectors
);
1024 * Set the IDT descriptor to a fixed read-only location, so that the
1025 * "sidt" instruction will not leak the location of the kernel, and
1026 * to defend the IDT against arbitrary memory write vulnerabilities.
1027 * It will be reloaded in cpu_init() */
1028 __set_fixmap(FIX_RO_IDT
, __pa_symbol(idt_table
), PAGE_KERNEL_RO
);
1029 idt_descr
.address
= fix_to_virt(FIX_RO_IDT
);
1032 * Should be a barrier for any external CPU state:
1037 * X86_TRAP_DB and X86_TRAP_BP have been set
1038 * in early_trap_init(). However, ITS works only after
1039 * cpu_init() loads TSS. See comments in early_trap_init().
1041 set_intr_gate_ist(X86_TRAP_DB
, &debug
, DEBUG_STACK
);
1042 /* int3 can be called from all */
1043 set_system_intr_gate_ist(X86_TRAP_BP
, &int3
, DEBUG_STACK
);
1045 x86_init
.irqs
.trap_init();
1047 #ifdef CONFIG_X86_64
1048 memcpy(&debug_idt_table
, &idt_table
, IDT_ENTRIES
* 16);
1049 set_nmi_gate(X86_TRAP_DB
, &debug
);
1050 set_nmi_gate(X86_TRAP_BP
, &int3
);