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;
302 unsigned long *p = (unsigned long *)regs->sp;
305 * regs->sp points to the failing IRET frame on the
306 * ESPFIX64 stack. Copy it to the entry stack. This fills
307 * in gpregs->ss through gpregs->ip.
312 gpregs->flags = p[2];
315 gpregs->orig_ax = 0; /* Missing (lost) #GP error code */
318 * Adjust our frame so that we return straight to the #GP
319 * vector with the expected RSP value. This is safe because
320 * we won't enable interupts or schedule before we invoke
321 * general_protection, so nothing will clobber the stack
322 * frame we just set up.
324 * We will enter general_protection with kernel GSBASE,
325 * which is what the stub expects, given that the faulting
326 * RIP will be the IRET instruction.
328 regs->ip = (unsigned long)general_protection;
329 regs->sp = (unsigned long)&gpregs->orig_ax;
336 notify_die(DIE_TRAP, str, regs, error_code, X86_TRAP_DF, SIGSEGV);
338 tsk->thread.error_code = error_code;
339 tsk->thread.trap_nr = X86_TRAP_DF;
341 #ifdef CONFIG_VMAP_STACK
343 * If we overflow the stack into a guard page, the CPU will fail
344 * to deliver #PF and will send #DF instead. Similarly, if we
345 * take any non-IST exception while too close to the bottom of
346 * the stack, the processor will get a page fault while
347 * delivering the exception and will generate a double fault.
349 * According to the SDM (footnote in 6.15 under "Interrupt 14 -
350 * Page-Fault Exception (#PF):
352 * Processors update CR2 whenever a page fault is detected. If a
353 * second page fault occurs while an earlier page fault is being
354 * delivered, the faulting linear address of the second fault will
355 * overwrite the contents of CR2 (replacing the previous
356 * address). These updates to CR2 occur even if the page fault
357 * results in a double fault or occurs during the delivery of a
360 * The logic below has a small possibility of incorrectly diagnosing
361 * some errors as stack overflows. For example, if the IDT or GDT
362 * gets corrupted such that #GP delivery fails due to a bad descriptor
363 * causing #GP and we hit this condition while CR2 coincidentally
364 * points to the stack guard page, we'll think we overflowed the
365 * stack. Given that we're going to panic one way or another
366 * if this happens, this isn't necessarily worth fixing.
368 * If necessary, we could improve the test by only diagnosing
369 * a stack overflow if the saved RSP points within 47 bytes of
370 * the bottom of the stack: if RSP == tsk_stack + 48 and we
371 * take an exception, the stack is already aligned and there
372 * will be enough room SS, RSP, RFLAGS, CS, RIP, and a
373 * possible error code, so a stack overflow would *not* double
374 * fault. With any less space left, exception delivery could
375 * fail, and, as a practical matter, we've overflowed the
376 * stack even if the actual trigger for the double fault was
379 if ((unsigned long)task_stack_page(tsk) - 1 - cr2 < PAGE_SIZE)
380 handle_stack_overflow("kernel stack overflow (double-fault)", regs, cr2);
383 pr_emerg("PANIC: double fault, error_code: 0x%lx\n", error_code);
384 die("double fault", regs, error_code);
385 panic("Machine halted.");
388 dotraplinkage void do_bounds(struct pt_regs *regs, long error_code)
390 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
391 if (notify_die(DIE_TRAP, "bounds", regs, error_code,
392 X86_TRAP_BR, SIGSEGV) == NOTIFY_STOP)
394 cond_local_irq_enable(regs);
396 if (!user_mode(regs))
397 die("bounds", regs, error_code);
399 do_trap(X86_TRAP_BR, SIGSEGV, "bounds", regs, error_code, 0, NULL);
402 enum kernel_gp_hint {
409 * When an uncaught #GP occurs, try to determine the memory address accessed by
410 * the instruction and return that address to the caller. Also, try to figure
411 * out whether any part of the access to that address was non-canonical.
413 static enum kernel_gp_hint get_kernel_gp_address(struct pt_regs *regs,
416 u8 insn_buf[MAX_INSN_SIZE];
419 if (probe_kernel_read(insn_buf, (void *)regs->ip, MAX_INSN_SIZE))
422 kernel_insn_init(&insn, insn_buf, MAX_INSN_SIZE);
423 insn_get_modrm(&insn);
426 *addr = (unsigned long)insn_get_addr_ref(&insn, regs);
433 * - the operand is not in the kernel half
434 * - the last byte of the operand is not in the user canonical half
436 if (*addr < ~__VIRTUAL_MASK &&
437 *addr + insn.opnd_bytes - 1 > __VIRTUAL_MASK)
438 return GP_NON_CANONICAL;
444 #define GPFSTR "general protection fault"
446 dotraplinkage void do_general_protection(struct pt_regs *regs, long error_code)
448 char desc[sizeof(GPFSTR) + 50 + 2*sizeof(unsigned long) + 1] = GPFSTR;
449 enum kernel_gp_hint hint = GP_NO_HINT;
450 struct task_struct *tsk;
451 unsigned long gp_addr;
454 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
455 cond_local_irq_enable(regs);
457 if (static_cpu_has(X86_FEATURE_UMIP)) {
458 if (user_mode(regs) && fixup_umip_exception(regs))
462 if (v8086_mode(regs)) {
464 handle_vm86_fault((struct kernel_vm86_regs *) regs, error_code);
470 if (user_mode(regs)) {
471 tsk->thread.error_code = error_code;
472 tsk->thread.trap_nr = X86_TRAP_GP;
474 show_signal(tsk, SIGSEGV, "", desc, regs, error_code);
480 if (fixup_exception(regs, X86_TRAP_GP, error_code, 0))
483 tsk->thread.error_code = error_code;
484 tsk->thread.trap_nr = X86_TRAP_GP;
487 * To be potentially processing a kprobe fault and to trust the result
488 * from kprobe_running(), we have to be non-preemptible.
490 if (!preemptible() &&
492 kprobe_fault_handler(regs, X86_TRAP_GP))
495 ret = notify_die(DIE_GPF, desc, regs, error_code, X86_TRAP_GP, SIGSEGV);
496 if (ret == NOTIFY_STOP)
500 snprintf(desc, sizeof(desc), "segment-related " GPFSTR);
502 hint = get_kernel_gp_address(regs, &gp_addr);
504 if (hint != GP_NO_HINT)
505 snprintf(desc, sizeof(desc), GPFSTR ", %s 0x%lx",
506 (hint == GP_NON_CANONICAL) ? "probably for non-canonical address"
507 : "maybe for address",
511 * KASAN is interested only in the non-canonical case, clear it
514 if (hint != GP_NON_CANONICAL)
517 die_addr(desc, regs, error_code, gp_addr);
520 NOKPROBE_SYMBOL(do_general_protection);
522 dotraplinkage void notrace do_int3(struct pt_regs *regs, long error_code)
524 if (poke_int3_handler(regs))
528 * Unlike any other non-IST entry, we can be called from pretty much
529 * any location in the kernel through kprobes -- text_poke() will most
530 * likely be handled by poke_int3_handler() above. This means this
531 * handler is effectively NMI-like.
533 if (!user_mode(regs))
536 #ifdef CONFIG_KGDB_LOW_LEVEL_TRAP
537 if (kgdb_ll_trap(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP,
538 SIGTRAP) == NOTIFY_STOP)
540 #endif /* CONFIG_KGDB_LOW_LEVEL_TRAP */
542 #ifdef CONFIG_KPROBES
543 if (kprobe_int3_handler(regs))
547 if (notify_die(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP,
548 SIGTRAP) == NOTIFY_STOP)
551 cond_local_irq_enable(regs);
552 do_trap(X86_TRAP_BP, SIGTRAP, "int3", regs, error_code, 0, NULL);
553 cond_local_irq_disable(regs);
556 if (!user_mode(regs))
559 NOKPROBE_SYMBOL(do_int3);
563 * Help handler running on a per-cpu (IST or entry trampoline) stack
564 * to switch to the normal thread stack if the interrupted code was in
565 * user mode. The actual stack switch is done in entry_64.S
567 asmlinkage __visible noinstr struct pt_regs *sync_regs(struct pt_regs *eregs)
569 struct pt_regs *regs = (struct pt_regs *)this_cpu_read(cpu_current_top_of_stack) - 1;
575 struct bad_iret_stack {
576 void *error_entry_ret;
580 asmlinkage __visible noinstr
581 struct bad_iret_stack *fixup_bad_iret(struct bad_iret_stack *s)
584 * This is called from entry_64.S early in handling a fault
585 * caused by a bad iret to user mode. To handle the fault
586 * correctly, we want to move our stack frame to where it would
587 * be had we entered directly on the entry stack (rather than
588 * just below the IRET frame) and we want to pretend that the
589 * exception came from the IRET target.
591 struct bad_iret_stack tmp, *new_stack =
592 (struct bad_iret_stack *)__this_cpu_read(cpu_tss_rw.x86_tss.sp0) - 1;
594 /* Copy the IRET target to the temporary storage. */
595 memcpy(&tmp.regs.ip, (void *)s->regs.sp, 5*8);
597 /* Copy the remainder of the stack from the current stack. */
598 memcpy(&tmp, s, offsetof(struct bad_iret_stack, regs.ip));
600 /* Update the entry stack */
601 memcpy(new_stack, &tmp, sizeof(tmp));
603 BUG_ON(!user_mode(&new_stack->regs));
608 static bool is_sysenter_singlestep(struct pt_regs *regs)
611 * We don't try for precision here. If we're anywhere in the region of
612 * code that can be single-stepped in the SYSENTER entry path, then
613 * assume that this is a useless single-step trap due to SYSENTER
614 * being invoked with TF set. (We don't know in advance exactly
615 * which instructions will be hit because BTF could plausibly
619 return (regs->ip - (unsigned long)__begin_SYSENTER_singlestep_region) <
620 (unsigned long)__end_SYSENTER_singlestep_region -
621 (unsigned long)__begin_SYSENTER_singlestep_region;
622 #elif defined(CONFIG_IA32_EMULATION)
623 return (regs->ip - (unsigned long)entry_SYSENTER_compat) <
624 (unsigned long)__end_entry_SYSENTER_compat -
625 (unsigned long)entry_SYSENTER_compat;
632 * Our handling of the processor debug registers is non-trivial.
633 * We do not clear them on entry and exit from the kernel. Therefore
634 * it is possible to get a watchpoint trap here from inside the kernel.
635 * However, the code in ./ptrace.c has ensured that the user can
636 * only set watchpoints on userspace addresses. Therefore the in-kernel
637 * watchpoint trap can only occur in code which is reading/writing
638 * from user space. Such code must not hold kernel locks (since it
639 * can equally take a page fault), therefore it is safe to call
640 * force_sig_info even though that claims and releases locks.
642 * Code in ./signal.c ensures that the debug control register
643 * is restored before we deliver any signal, and therefore that
644 * user code runs with the correct debug control register even though
647 * Being careful here means that we don't have to be as careful in a
648 * lot of more complicated places (task switching can be a bit lazy
649 * about restoring all the debug state, and ptrace doesn't have to
650 * find every occurrence of the TF bit that could be saved away even
653 * May run on IST stack.
655 dotraplinkage void do_debug(struct pt_regs *regs, long error_code)
657 struct task_struct *tsk = current;
664 get_debugreg(dr6, 6);
666 * The Intel SDM says:
668 * Certain debug exceptions may clear bits 0-3. The remaining
669 * contents of the DR6 register are never cleared by the
670 * processor. To avoid confusion in identifying debug
671 * exceptions, debug handlers should clear the register before
672 * returning to the interrupted task.
674 * Keep it simple: clear DR6 immediately.
678 /* Filter out all the reserved bits which are preset to 1 */
679 dr6 &= ~DR6_RESERVED;
682 * The SDM says "The processor clears the BTF flag when it
683 * generates a debug exception." Clear TIF_BLOCKSTEP to keep
684 * TIF_BLOCKSTEP in sync with the hardware BTF flag.
686 clear_tsk_thread_flag(tsk, TIF_BLOCKSTEP);
688 if (unlikely(!user_mode(regs) && (dr6 & DR_STEP) &&
689 is_sysenter_singlestep(regs))) {
694 * else we might have gotten a single-step trap and hit a
695 * watchpoint at the same time, in which case we should fall
696 * through and handle the watchpoint.
701 * If dr6 has no reason to give us about the origin of this trap,
702 * then it's very likely the result of an icebp/int01 trap.
703 * User wants a sigtrap for that.
705 if (!dr6 && user_mode(regs))
708 /* Store the virtualized DR6 value */
709 tsk->thread.debugreg6 = dr6;
711 #ifdef CONFIG_KPROBES
712 if (kprobe_debug_handler(regs))
716 if (notify_die(DIE_DEBUG, "debug", regs, (long)&dr6, error_code,
717 SIGTRAP) == NOTIFY_STOP)
721 * Let others (NMI) know that the debug stack is in use
722 * as we may switch to the interrupt stack.
724 debug_stack_usage_inc();
726 /* It's safe to allow irq's after DR6 has been saved */
727 cond_local_irq_enable(regs);
729 if (v8086_mode(regs)) {
730 handle_vm86_trap((struct kernel_vm86_regs *) regs, error_code,
732 cond_local_irq_disable(regs);
733 debug_stack_usage_dec();
737 if (WARN_ON_ONCE((dr6 & DR_STEP) && !user_mode(regs))) {
739 * Historical junk that used to handle SYSENTER single-stepping.
740 * This should be unreachable now. If we survive for a while
741 * without anyone hitting this warning, we'll turn this into
744 tsk->thread.debugreg6 &= ~DR_STEP;
745 set_tsk_thread_flag(tsk, TIF_SINGLESTEP);
746 regs->flags &= ~X86_EFLAGS_TF;
748 si_code = get_si_code(tsk->thread.debugreg6);
749 if (tsk->thread.debugreg6 & (DR_STEP | DR_TRAP_BITS) || user_icebp)
750 send_sigtrap(regs, error_code, si_code);
751 cond_local_irq_disable(regs);
752 debug_stack_usage_dec();
757 NOKPROBE_SYMBOL(do_debug);
760 * Note that we play around with the 'TS' bit in an attempt to get
761 * the correct behaviour even in the presence of the asynchronous
764 static void math_error(struct pt_regs *regs, int error_code, int trapnr)
766 struct task_struct *task = current;
767 struct fpu *fpu = &task->thread.fpu;
769 char *str = (trapnr == X86_TRAP_MF) ? "fpu exception" :
772 cond_local_irq_enable(regs);
774 if (!user_mode(regs)) {
775 if (fixup_exception(regs, trapnr, error_code, 0))
778 task->thread.error_code = error_code;
779 task->thread.trap_nr = trapnr;
781 if (notify_die(DIE_TRAP, str, regs, error_code,
782 trapnr, SIGFPE) != NOTIFY_STOP)
783 die(str, regs, error_code);
788 * Save the info for the exception handler and clear the error.
792 task->thread.trap_nr = trapnr;
793 task->thread.error_code = error_code;
795 si_code = fpu__exception_code(fpu, trapnr);
796 /* Retry when we get spurious exceptions: */
800 force_sig_fault(SIGFPE, si_code,
801 (void __user *)uprobe_get_trap_addr(regs));
804 dotraplinkage void do_coprocessor_error(struct pt_regs *regs, long error_code)
806 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
807 math_error(regs, error_code, X86_TRAP_MF);
811 do_simd_coprocessor_error(struct pt_regs *regs, long error_code)
813 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
814 math_error(regs, error_code, X86_TRAP_XF);
818 do_spurious_interrupt_bug(struct pt_regs *regs, long error_code)
821 * This addresses a Pentium Pro Erratum:
823 * PROBLEM: If the APIC subsystem is configured in mixed mode with
824 * Virtual Wire mode implemented through the local APIC, an
825 * interrupt vector of 0Fh (Intel reserved encoding) may be
826 * generated by the local APIC (Int 15). This vector may be
827 * generated upon receipt of a spurious interrupt (an interrupt
828 * which is removed before the system receives the INTA sequence)
829 * instead of the programmed 8259 spurious interrupt vector.
831 * IMPLICATION: The spurious interrupt vector programmed in the
832 * 8259 is normally handled by an operating system's spurious
833 * interrupt handler. However, a vector of 0Fh is unknown to some
834 * operating systems, which would crash if this erratum occurred.
836 * In theory this could be limited to 32bit, but the handler is not
837 * hurting and who knows which other CPUs suffer from this.
842 do_device_not_available(struct pt_regs *regs, long error_code)
844 unsigned long cr0 = read_cr0();
846 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
848 #ifdef CONFIG_MATH_EMULATION
849 if (!boot_cpu_has(X86_FEATURE_FPU) && (cr0 & X86_CR0_EM)) {
850 struct math_emu_info info = { };
852 cond_local_irq_enable(regs);
860 /* This should not happen. */
861 if (WARN(cr0 & X86_CR0_TS, "CR0.TS was set")) {
862 /* Try to fix it up and carry on. */
863 write_cr0(cr0 & ~X86_CR0_TS);
866 * Something terrible happened, and we're better off trying
867 * to kill the task than getting stuck in a never-ending
868 * loop of #NM faults.
870 die("unexpected #NM exception", regs, error_code);
873 NOKPROBE_SYMBOL(do_device_not_available);
876 dotraplinkage void do_iret_error(struct pt_regs *regs, long error_code)
878 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
881 if (notify_die(DIE_TRAP, "iret exception", regs, error_code,
882 X86_TRAP_IRET, SIGILL) != NOTIFY_STOP) {
883 do_trap(X86_TRAP_IRET, SIGILL, "iret exception", regs, error_code,
884 ILL_BADSTK, (void __user *)NULL);
889 void __init trap_init(void)
891 /* Init cpu_entry_area before IST entries are set up */
892 setup_cpu_entry_areas();
897 * Set the IDT descriptor to a fixed read-only location, so that the
898 * "sidt" instruction will not leak the location of the kernel, and
899 * to defend the IDT against arbitrary memory write vulnerabilities.
900 * It will be reloaded in cpu_init() */
901 cea_set_pte(CPU_ENTRY_AREA_RO_IDT_VADDR, __pa_symbol(idt_table),
903 idt_descr.address = CPU_ENTRY_AREA_RO_IDT;
906 * Should be a barrier for any external CPU state:
910 idt_setup_ist_traps();
912 idt_setup_debugidt_traps();