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>
40 #include <linux/hardirq.h>
41 #include <linux/atomic.h>
43 #include <asm/stacktrace.h>
44 #include <asm/processor.h>
45 #include <asm/debugreg.h>
46 #include <asm/text-patching.h>
47 #include <asm/ftrace.h>
48 #include <asm/traps.h>
50 #include <asm/fpu/internal.h>
52 #include <asm/cpu_entry_area.h>
54 #include <asm/fixmap.h>
55 #include <asm/mach_traps.h>
56 #include <asm/alternative.h>
57 #include <asm/fpu/xstate.h>
61 #include <asm/insn-eval.h>
64 #include <asm/x86_init.h>
65 #include <asm/pgalloc.h>
66 #include <asm/proto.h>
68 #include <asm/processor-flags.h>
69 #include <asm/setup.h>
70 #include <asm/proto.h>
73 DECLARE_BITMAP(system_vectors, NR_VECTORS);
75 static inline void cond_local_irq_enable(struct pt_regs *regs)
77 if (regs->flags & X86_EFLAGS_IF)
81 static inline void cond_local_irq_disable(struct pt_regs *regs)
83 if (regs->flags & X86_EFLAGS_IF)
87 int is_valid_bugaddr(unsigned long addr)
91 if (addr < TASK_SIZE_MAX)
94 if (probe_kernel_address((unsigned short *)addr, ud))
97 return ud == INSN_UD0 || ud == INSN_UD2;
100 int fixup_bug(struct pt_regs *regs, int trapnr)
102 if (trapnr != X86_TRAP_UD)
105 switch (report_bug(regs->ip, regs)) {
106 case BUG_TRAP_TYPE_NONE:
107 case BUG_TRAP_TYPE_BUG:
110 case BUG_TRAP_TYPE_WARN:
118 static nokprobe_inline int
119 do_trap_no_signal(struct task_struct *tsk, int trapnr, const char *str,
120 struct pt_regs *regs, long error_code)
122 if (v8086_mode(regs)) {
124 * Traps 0, 1, 3, 4, and 5 should be forwarded to vm86.
125 * On nmi (interrupt 2), do_trap should not be called.
127 if (trapnr < X86_TRAP_UD) {
128 if (!handle_vm86_trap((struct kernel_vm86_regs *) regs,
132 } else if (!user_mode(regs)) {
133 if (fixup_exception(regs, trapnr, error_code, 0))
136 tsk->thread.error_code = error_code;
137 tsk->thread.trap_nr = trapnr;
138 die(str, regs, error_code);
142 * We want error_code and trap_nr set for userspace faults and
143 * kernelspace faults which result in die(), but not
144 * kernelspace faults which are fixed up. die() gives the
145 * process no chance to handle the signal and notice the
146 * kernel fault information, so that won't result in polluting
147 * the information about previously queued, but not yet
148 * delivered, faults. See also do_general_protection below.
150 tsk->thread.error_code = error_code;
151 tsk->thread.trap_nr = trapnr;
156 static void show_signal(struct task_struct *tsk, int signr,
157 const char *type, const char *desc,
158 struct pt_regs *regs, long error_code)
160 if (show_unhandled_signals && unhandled_signal(tsk, signr) &&
161 printk_ratelimit()) {
162 pr_info("%s[%d] %s%s ip:%lx sp:%lx error:%lx",
163 tsk->comm, task_pid_nr(tsk), type, desc,
164 regs->ip, regs->sp, error_code);
165 print_vma_addr(KERN_CONT " in ", regs->ip);
171 do_trap(int trapnr, int signr, char *str, struct pt_regs *regs,
172 long error_code, int sicode, void __user *addr)
174 struct task_struct *tsk = current;
176 if (!do_trap_no_signal(tsk, trapnr, str, regs, error_code))
179 show_signal(tsk, signr, "trap ", str, regs, error_code);
184 force_sig_fault(signr, sicode, addr);
186 NOKPROBE_SYMBOL(do_trap);
188 static void do_error_trap(struct pt_regs *regs, long error_code, char *str,
189 unsigned long trapnr, int signr, int sicode, void __user *addr)
191 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
194 * WARN*()s end up here; fix them up before we call the
197 if (!user_mode(regs) && fixup_bug(regs, trapnr))
200 if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) !=
202 cond_local_irq_enable(regs);
203 do_trap(trapnr, signr, str, regs, error_code, sicode, addr);
207 #define IP ((void __user *)uprobe_get_trap_addr(regs))
208 #define DO_ERROR(trapnr, signr, sicode, addr, str, name) \
209 dotraplinkage void do_##name(struct pt_regs *regs, long error_code) \
211 do_error_trap(regs, error_code, str, trapnr, signr, sicode, addr); \
214 DO_ERROR(X86_TRAP_DE, SIGFPE, FPE_INTDIV, IP, "divide error", divide_error)
215 DO_ERROR(X86_TRAP_OF, SIGSEGV, 0, NULL, "overflow", overflow)
216 DO_ERROR(X86_TRAP_UD, SIGILL, ILL_ILLOPN, IP, "invalid opcode", invalid_op)
217 DO_ERROR(X86_TRAP_OLD_MF, SIGFPE, 0, NULL, "coprocessor segment overrun", coprocessor_segment_overrun)
218 DO_ERROR(X86_TRAP_TS, SIGSEGV, 0, NULL, "invalid TSS", invalid_TSS)
219 DO_ERROR(X86_TRAP_NP, SIGBUS, 0, NULL, "segment not present", segment_not_present)
220 DO_ERROR(X86_TRAP_SS, SIGBUS, 0, NULL, "stack segment", stack_segment)
223 dotraplinkage void do_alignment_check(struct pt_regs *regs, long error_code)
225 char *str = "alignment check";
227 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
229 if (notify_die(DIE_TRAP, str, regs, error_code, X86_TRAP_AC, SIGBUS) == NOTIFY_STOP)
232 if (!user_mode(regs))
233 die("Split lock detected\n", regs, error_code);
237 if (handle_user_split_lock(regs, error_code))
240 do_trap(X86_TRAP_AC, SIGBUS, "alignment check", regs,
241 error_code, BUS_ADRALN, NULL);
244 #ifdef CONFIG_VMAP_STACK
245 __visible void __noreturn handle_stack_overflow(const char *message,
246 struct pt_regs *regs,
247 unsigned long fault_address)
249 printk(KERN_EMERG "BUG: stack guard page was hit at %p (stack is %p..%p)\n",
250 (void *)fault_address, current->stack,
251 (char *)current->stack + THREAD_SIZE - 1);
252 die(message, regs, 0);
254 /* Be absolutely certain we don't return. */
255 panic("%s", message);
260 * Runs on an IST stack for x86_64 and on a special task stack for x86_32.
262 * On x86_64, this is more or less a normal kernel entry. Notwithstanding the
263 * SDM's warnings about double faults being unrecoverable, returning works as
264 * expected. Presumably what the SDM actually means is that the CPU may get
265 * the register state wrong on entry, so returning could be a bad idea.
267 * Various CPU engineers have promised that double faults due to an IRET fault
268 * while the stack is read-only are, in fact, recoverable.
270 * On x86_32, this is entered through a task gate, and regs are synthesized
271 * from the TSS. Returning is, in principle, okay, but changes to regs will
272 * be lost. If, for some reason, we need to return to a context with modified
273 * regs, the shim code could be adjusted to synchronize the registers.
275 dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code, unsigned long cr2)
277 static const char str[] = "double fault";
278 struct task_struct *tsk = current;
280 #ifdef CONFIG_X86_ESPFIX64
281 extern unsigned char native_irq_return_iret[];
284 * If IRET takes a non-IST fault on the espfix64 stack, then we
285 * end up promoting it to a doublefault. In that case, take
286 * advantage of the fact that we're not using the normal (TSS.sp0)
287 * stack right now. We can write a fake #GP(0) frame at TSS.sp0
288 * and then modify our own IRET frame so that, when we return,
289 * we land directly at the #GP(0) vector with the stack already
290 * set up according to its expectations.
292 * The net result is that our #GP handler will think that we
293 * entered from usermode with the bad user context.
295 * No need for nmi_enter() here because we don't use RCU.
297 if (((long)regs->sp >> P4D_SHIFT) == ESPFIX_PGD_ENTRY &&
298 regs->cs == __KERNEL_CS &&
299 regs->ip == (unsigned long)native_irq_return_iret)
301 struct pt_regs *gpregs = (struct pt_regs *)this_cpu_read(cpu_tss_rw.x86_tss.sp0) - 1;
304 * regs->sp points to the failing IRET frame on the
305 * ESPFIX64 stack. Copy it to the entry stack. This fills
306 * in gpregs->ss through gpregs->ip.
309 memmove(&gpregs->ip, (void *)regs->sp, 5*8);
310 gpregs->orig_ax = 0; /* Missing (lost) #GP error code */
313 * Adjust our frame so that we return straight to the #GP
314 * vector with the expected RSP value. This is safe because
315 * we won't enable interupts or schedule before we invoke
316 * general_protection, so nothing will clobber the stack
317 * frame we just set up.
319 * We will enter general_protection with kernel GSBASE,
320 * which is what the stub expects, given that the faulting
321 * RIP will be the IRET instruction.
323 regs->ip = (unsigned long)general_protection;
324 regs->sp = (unsigned long)&gpregs->orig_ax;
331 notify_die(DIE_TRAP, str, regs, error_code, X86_TRAP_DF, SIGSEGV);
333 tsk->thread.error_code = error_code;
334 tsk->thread.trap_nr = X86_TRAP_DF;
336 #ifdef CONFIG_VMAP_STACK
338 * If we overflow the stack into a guard page, the CPU will fail
339 * to deliver #PF and will send #DF instead. Similarly, if we
340 * take any non-IST exception while too close to the bottom of
341 * the stack, the processor will get a page fault while
342 * delivering the exception and will generate a double fault.
344 * According to the SDM (footnote in 6.15 under "Interrupt 14 -
345 * Page-Fault Exception (#PF):
347 * Processors update CR2 whenever a page fault is detected. If a
348 * second page fault occurs while an earlier page fault is being
349 * delivered, the faulting linear address of the second fault will
350 * overwrite the contents of CR2 (replacing the previous
351 * address). These updates to CR2 occur even if the page fault
352 * results in a double fault or occurs during the delivery of a
355 * The logic below has a small possibility of incorrectly diagnosing
356 * some errors as stack overflows. For example, if the IDT or GDT
357 * gets corrupted such that #GP delivery fails due to a bad descriptor
358 * causing #GP and we hit this condition while CR2 coincidentally
359 * points to the stack guard page, we'll think we overflowed the
360 * stack. Given that we're going to panic one way or another
361 * if this happens, this isn't necessarily worth fixing.
363 * If necessary, we could improve the test by only diagnosing
364 * a stack overflow if the saved RSP points within 47 bytes of
365 * the bottom of the stack: if RSP == tsk_stack + 48 and we
366 * take an exception, the stack is already aligned and there
367 * will be enough room SS, RSP, RFLAGS, CS, RIP, and a
368 * possible error code, so a stack overflow would *not* double
369 * fault. With any less space left, exception delivery could
370 * fail, and, as a practical matter, we've overflowed the
371 * stack even if the actual trigger for the double fault was
374 if ((unsigned long)task_stack_page(tsk) - 1 - cr2 < PAGE_SIZE)
375 handle_stack_overflow("kernel stack overflow (double-fault)", regs, cr2);
378 pr_emerg("PANIC: double fault, error_code: 0x%lx\n", error_code);
379 die("double fault", regs, error_code);
380 panic("Machine halted.");
383 dotraplinkage void do_bounds(struct pt_regs *regs, long error_code)
385 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
386 if (notify_die(DIE_TRAP, "bounds", regs, error_code,
387 X86_TRAP_BR, SIGSEGV) == NOTIFY_STOP)
389 cond_local_irq_enable(regs);
391 if (!user_mode(regs))
392 die("bounds", regs, error_code);
394 do_trap(X86_TRAP_BR, SIGSEGV, "bounds", regs, error_code, 0, NULL);
397 enum kernel_gp_hint {
404 * When an uncaught #GP occurs, try to determine the memory address accessed by
405 * the instruction and return that address to the caller. Also, try to figure
406 * out whether any part of the access to that address was non-canonical.
408 static enum kernel_gp_hint get_kernel_gp_address(struct pt_regs *regs,
411 u8 insn_buf[MAX_INSN_SIZE];
414 if (probe_kernel_read(insn_buf, (void *)regs->ip, MAX_INSN_SIZE))
417 kernel_insn_init(&insn, insn_buf, MAX_INSN_SIZE);
418 insn_get_modrm(&insn);
421 *addr = (unsigned long)insn_get_addr_ref(&insn, regs);
428 * - the operand is not in the kernel half
429 * - the last byte of the operand is not in the user canonical half
431 if (*addr < ~__VIRTUAL_MASK &&
432 *addr + insn.opnd_bytes - 1 > __VIRTUAL_MASK)
433 return GP_NON_CANONICAL;
439 #define GPFSTR "general protection fault"
441 dotraplinkage void do_general_protection(struct pt_regs *regs, long error_code)
443 char desc[sizeof(GPFSTR) + 50 + 2*sizeof(unsigned long) + 1] = GPFSTR;
444 enum kernel_gp_hint hint = GP_NO_HINT;
445 struct task_struct *tsk;
446 unsigned long gp_addr;
449 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
450 cond_local_irq_enable(regs);
452 if (static_cpu_has(X86_FEATURE_UMIP)) {
453 if (user_mode(regs) && fixup_umip_exception(regs))
457 if (v8086_mode(regs)) {
459 handle_vm86_fault((struct kernel_vm86_regs *) regs, error_code);
465 if (user_mode(regs)) {
466 tsk->thread.error_code = error_code;
467 tsk->thread.trap_nr = X86_TRAP_GP;
469 show_signal(tsk, SIGSEGV, "", desc, regs, error_code);
475 if (fixup_exception(regs, X86_TRAP_GP, error_code, 0))
478 tsk->thread.error_code = error_code;
479 tsk->thread.trap_nr = X86_TRAP_GP;
482 * To be potentially processing a kprobe fault and to trust the result
483 * from kprobe_running(), we have to be non-preemptible.
485 if (!preemptible() &&
487 kprobe_fault_handler(regs, X86_TRAP_GP))
490 ret = notify_die(DIE_GPF, desc, regs, error_code, X86_TRAP_GP, SIGSEGV);
491 if (ret == NOTIFY_STOP)
495 snprintf(desc, sizeof(desc), "segment-related " GPFSTR);
497 hint = get_kernel_gp_address(regs, &gp_addr);
499 if (hint != GP_NO_HINT)
500 snprintf(desc, sizeof(desc), GPFSTR ", %s 0x%lx",
501 (hint == GP_NON_CANONICAL) ? "probably for non-canonical address"
502 : "maybe for address",
506 * KASAN is interested only in the non-canonical case, clear it
509 if (hint != GP_NON_CANONICAL)
512 die_addr(desc, regs, error_code, gp_addr);
515 NOKPROBE_SYMBOL(do_general_protection);
517 dotraplinkage void notrace do_int3(struct pt_regs *regs, long error_code)
519 if (poke_int3_handler(regs))
523 * Unlike any other non-IST entry, we can be called from pretty much
524 * any location in the kernel through kprobes -- text_poke() will most
525 * likely be handled by poke_int3_handler() above. This means this
526 * handler is effectively NMI-like.
528 if (!user_mode(regs))
531 #ifdef CONFIG_KGDB_LOW_LEVEL_TRAP
532 if (kgdb_ll_trap(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP,
533 SIGTRAP) == NOTIFY_STOP)
535 #endif /* CONFIG_KGDB_LOW_LEVEL_TRAP */
537 #ifdef CONFIG_KPROBES
538 if (kprobe_int3_handler(regs))
542 if (notify_die(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP,
543 SIGTRAP) == NOTIFY_STOP)
546 cond_local_irq_enable(regs);
547 do_trap(X86_TRAP_BP, SIGTRAP, "int3", regs, error_code, 0, NULL);
548 cond_local_irq_disable(regs);
551 if (!user_mode(regs))
554 NOKPROBE_SYMBOL(do_int3);
558 * Help handler running on a per-cpu (IST or entry trampoline) stack
559 * to switch to the normal thread stack if the interrupted code was in
560 * user mode. The actual stack switch is done in entry_64.S
562 asmlinkage __visible notrace struct pt_regs *sync_regs(struct pt_regs *eregs)
564 struct pt_regs *regs = (struct pt_regs *)this_cpu_read(cpu_current_top_of_stack) - 1;
569 NOKPROBE_SYMBOL(sync_regs);
571 struct bad_iret_stack {
572 void *error_entry_ret;
576 asmlinkage __visible notrace
577 struct bad_iret_stack *fixup_bad_iret(struct bad_iret_stack *s)
580 * This is called from entry_64.S early in handling a fault
581 * caused by a bad iret to user mode. To handle the fault
582 * correctly, we want to move our stack frame to where it would
583 * be had we entered directly on the entry stack (rather than
584 * just below the IRET frame) and we want to pretend that the
585 * exception came from the IRET target.
587 struct bad_iret_stack *new_stack =
588 (struct bad_iret_stack *)this_cpu_read(cpu_tss_rw.x86_tss.sp0) - 1;
590 /* Copy the IRET target to the new stack. */
591 memmove(&new_stack->regs.ip, (void *)s->regs.sp, 5*8);
593 /* Copy the remainder of the stack from the current stack. */
594 memmove(new_stack, s, offsetof(struct bad_iret_stack, regs.ip));
596 BUG_ON(!user_mode(&new_stack->regs));
599 NOKPROBE_SYMBOL(fixup_bad_iret);
602 static bool is_sysenter_singlestep(struct pt_regs *regs)
605 * We don't try for precision here. If we're anywhere in the region of
606 * code that can be single-stepped in the SYSENTER entry path, then
607 * assume that this is a useless single-step trap due to SYSENTER
608 * being invoked with TF set. (We don't know in advance exactly
609 * which instructions will be hit because BTF could plausibly
613 return (regs->ip - (unsigned long)__begin_SYSENTER_singlestep_region) <
614 (unsigned long)__end_SYSENTER_singlestep_region -
615 (unsigned long)__begin_SYSENTER_singlestep_region;
616 #elif defined(CONFIG_IA32_EMULATION)
617 return (regs->ip - (unsigned long)entry_SYSENTER_compat) <
618 (unsigned long)__end_entry_SYSENTER_compat -
619 (unsigned long)entry_SYSENTER_compat;
626 * Our handling of the processor debug registers is non-trivial.
627 * We do not clear them on entry and exit from the kernel. Therefore
628 * it is possible to get a watchpoint trap here from inside the kernel.
629 * However, the code in ./ptrace.c has ensured that the user can
630 * only set watchpoints on userspace addresses. Therefore the in-kernel
631 * watchpoint trap can only occur in code which is reading/writing
632 * from user space. Such code must not hold kernel locks (since it
633 * can equally take a page fault), therefore it is safe to call
634 * force_sig_info even though that claims and releases locks.
636 * Code in ./signal.c ensures that the debug control register
637 * is restored before we deliver any signal, and therefore that
638 * user code runs with the correct debug control register even though
641 * Being careful here means that we don't have to be as careful in a
642 * lot of more complicated places (task switching can be a bit lazy
643 * about restoring all the debug state, and ptrace doesn't have to
644 * find every occurrence of the TF bit that could be saved away even
647 * May run on IST stack.
649 dotraplinkage void do_debug(struct pt_regs *regs, long error_code)
651 struct task_struct *tsk = current;
658 get_debugreg(dr6, 6);
660 * The Intel SDM says:
662 * Certain debug exceptions may clear bits 0-3. The remaining
663 * contents of the DR6 register are never cleared by the
664 * processor. To avoid confusion in identifying debug
665 * exceptions, debug handlers should clear the register before
666 * returning to the interrupted task.
668 * Keep it simple: clear DR6 immediately.
672 /* Filter out all the reserved bits which are preset to 1 */
673 dr6 &= ~DR6_RESERVED;
676 * The SDM says "The processor clears the BTF flag when it
677 * generates a debug exception." Clear TIF_BLOCKSTEP to keep
678 * TIF_BLOCKSTEP in sync with the hardware BTF flag.
680 clear_tsk_thread_flag(tsk, TIF_BLOCKSTEP);
682 if (unlikely(!user_mode(regs) && (dr6 & DR_STEP) &&
683 is_sysenter_singlestep(regs))) {
688 * else we might have gotten a single-step trap and hit a
689 * watchpoint at the same time, in which case we should fall
690 * through and handle the watchpoint.
695 * If dr6 has no reason to give us about the origin of this trap,
696 * then it's very likely the result of an icebp/int01 trap.
697 * User wants a sigtrap for that.
699 if (!dr6 && user_mode(regs))
702 /* Store the virtualized DR6 value */
703 tsk->thread.debugreg6 = dr6;
705 #ifdef CONFIG_KPROBES
706 if (kprobe_debug_handler(regs))
710 if (notify_die(DIE_DEBUG, "debug", regs, (long)&dr6, error_code,
711 SIGTRAP) == NOTIFY_STOP)
715 * Let others (NMI) know that the debug stack is in use
716 * as we may switch to the interrupt stack.
718 debug_stack_usage_inc();
720 /* It's safe to allow irq's after DR6 has been saved */
721 cond_local_irq_enable(regs);
723 if (v8086_mode(regs)) {
724 handle_vm86_trap((struct kernel_vm86_regs *) regs, error_code,
726 cond_local_irq_disable(regs);
727 debug_stack_usage_dec();
731 if (WARN_ON_ONCE((dr6 & DR_STEP) && !user_mode(regs))) {
733 * Historical junk that used to handle SYSENTER single-stepping.
734 * This should be unreachable now. If we survive for a while
735 * without anyone hitting this warning, we'll turn this into
738 tsk->thread.debugreg6 &= ~DR_STEP;
739 set_tsk_thread_flag(tsk, TIF_SINGLESTEP);
740 regs->flags &= ~X86_EFLAGS_TF;
742 si_code = get_si_code(tsk->thread.debugreg6);
743 if (tsk->thread.debugreg6 & (DR_STEP | DR_TRAP_BITS) || user_icebp)
744 send_sigtrap(regs, error_code, si_code);
745 cond_local_irq_disable(regs);
746 debug_stack_usage_dec();
751 NOKPROBE_SYMBOL(do_debug);
754 * Note that we play around with the 'TS' bit in an attempt to get
755 * the correct behaviour even in the presence of the asynchronous
758 static void math_error(struct pt_regs *regs, int error_code, int trapnr)
760 struct task_struct *task = current;
761 struct fpu *fpu = &task->thread.fpu;
763 char *str = (trapnr == X86_TRAP_MF) ? "fpu exception" :
766 cond_local_irq_enable(regs);
768 if (!user_mode(regs)) {
769 if (fixup_exception(regs, trapnr, error_code, 0))
772 task->thread.error_code = error_code;
773 task->thread.trap_nr = trapnr;
775 if (notify_die(DIE_TRAP, str, regs, error_code,
776 trapnr, SIGFPE) != NOTIFY_STOP)
777 die(str, regs, error_code);
782 * Save the info for the exception handler and clear the error.
786 task->thread.trap_nr = trapnr;
787 task->thread.error_code = error_code;
789 si_code = fpu__exception_code(fpu, trapnr);
790 /* Retry when we get spurious exceptions: */
794 force_sig_fault(SIGFPE, si_code,
795 (void __user *)uprobe_get_trap_addr(regs));
798 dotraplinkage void do_coprocessor_error(struct pt_regs *regs, long error_code)
800 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
801 math_error(regs, error_code, X86_TRAP_MF);
805 do_simd_coprocessor_error(struct pt_regs *regs, long error_code)
807 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
808 math_error(regs, error_code, X86_TRAP_XF);
812 do_spurious_interrupt_bug(struct pt_regs *regs, long error_code)
815 * This addresses a Pentium Pro Erratum:
817 * PROBLEM: If the APIC subsystem is configured in mixed mode with
818 * Virtual Wire mode implemented through the local APIC, an
819 * interrupt vector of 0Fh (Intel reserved encoding) may be
820 * generated by the local APIC (Int 15). This vector may be
821 * generated upon receipt of a spurious interrupt (an interrupt
822 * which is removed before the system receives the INTA sequence)
823 * instead of the programmed 8259 spurious interrupt vector.
825 * IMPLICATION: The spurious interrupt vector programmed in the
826 * 8259 is normally handled by an operating system's spurious
827 * interrupt handler. However, a vector of 0Fh is unknown to some
828 * operating systems, which would crash if this erratum occurred.
830 * In theory this could be limited to 32bit, but the handler is not
831 * hurting and who knows which other CPUs suffer from this.
836 do_device_not_available(struct pt_regs *regs, long error_code)
838 unsigned long cr0 = read_cr0();
840 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
842 #ifdef CONFIG_MATH_EMULATION
843 if (!boot_cpu_has(X86_FEATURE_FPU) && (cr0 & X86_CR0_EM)) {
844 struct math_emu_info info = { };
846 cond_local_irq_enable(regs);
854 /* This should not happen. */
855 if (WARN(cr0 & X86_CR0_TS, "CR0.TS was set")) {
856 /* Try to fix it up and carry on. */
857 write_cr0(cr0 & ~X86_CR0_TS);
860 * Something terrible happened, and we're better off trying
861 * to kill the task than getting stuck in a never-ending
862 * loop of #NM faults.
864 die("unexpected #NM exception", regs, error_code);
867 NOKPROBE_SYMBOL(do_device_not_available);
870 dotraplinkage void do_iret_error(struct pt_regs *regs, long error_code)
872 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
875 if (notify_die(DIE_TRAP, "iret exception", regs, error_code,
876 X86_TRAP_IRET, SIGILL) != NOTIFY_STOP) {
877 do_trap(X86_TRAP_IRET, SIGILL, "iret exception", regs, error_code,
878 ILL_BADSTK, (void __user *)NULL);
883 void __init trap_init(void)
885 /* Init cpu_entry_area before IST entries are set up */
886 setup_cpu_entry_areas();
891 * Set the IDT descriptor to a fixed read-only location, so that the
892 * "sidt" instruction will not leak the location of the kernel, and
893 * to defend the IDT against arbitrary memory write vulnerabilities.
894 * It will be reloaded in cpu_init() */
895 cea_set_pte(CPU_ENTRY_AREA_RO_IDT_VADDR, __pa_symbol(idt_table),
897 idt_descr.address = CPU_ENTRY_AREA_RO_IDT;
900 * Should be a barrier for any external CPU state:
904 idt_setup_ist_traps();
906 idt_setup_debugidt_traps();