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/module.h>
25 #include <linux/ptrace.h>
26 #include <linux/string.h>
27 #include <linux/delay.h>
28 #include <linux/errno.h>
29 #include <linux/kexec.h>
30 #include <linux/sched.h>
31 #include <linux/timer.h>
32 #include <linux/init.h>
33 #include <linux/bug.h>
34 #include <linux/nmi.h>
36 #include <linux/smp.h>
40 #include <linux/ioport.h>
41 #include <linux/eisa.h>
44 #if defined(CONFIG_EDAC)
45 #include <linux/edac.h>
48 #include <asm/kmemcheck.h>
49 #include <asm/stacktrace.h>
50 #include <asm/processor.h>
51 #include <asm/debugreg.h>
52 #include <linux/atomic.h>
53 #include <asm/ftrace.h>
54 #include <asm/traps.h>
57 #include <asm/fpu-internal.h>
59 #include <asm/fixmap.h>
60 #include <asm/mach_traps.h>
63 #include <asm/x86_init.h>
64 #include <asm/pgalloc.h>
65 #include <asm/proto.h>
67 #include <asm/processor-flags.h>
68 #include <asm/setup.h>
70 asmlinkage int system_call(void);
73 * The IDT has to be page-aligned to simplify the Pentium
74 * F0 0F bug workaround.
76 gate_desc idt_table[NR_VECTORS] __page_aligned_data = { { { { 0, 0 } } }, };
79 DECLARE_BITMAP(used_vectors, NR_VECTORS);
80 EXPORT_SYMBOL_GPL(used_vectors);
82 static inline void conditional_sti(struct pt_regs *regs)
84 if (regs->flags & X86_EFLAGS_IF)
88 static inline void preempt_conditional_sti(struct pt_regs *regs)
91 if (regs->flags & X86_EFLAGS_IF)
95 static inline void conditional_cli(struct pt_regs *regs)
97 if (regs->flags & X86_EFLAGS_IF)
101 static inline void preempt_conditional_cli(struct pt_regs *regs)
103 if (regs->flags & X86_EFLAGS_IF)
109 do_trap_no_signal(struct task_struct *tsk, int trapnr, char *str,
110 struct pt_regs *regs, long error_code)
113 if (regs->flags & X86_VM_MASK) {
115 * Traps 0, 1, 3, 4, and 5 should be forwarded to vm86.
116 * On nmi (interrupt 2), do_trap should not be called.
118 if (trapnr < X86_TRAP_UD) {
119 if (!handle_vm86_trap((struct kernel_vm86_regs *) regs,
126 if (!user_mode(regs)) {
127 if (!fixup_exception(regs)) {
128 tsk->thread.error_code = error_code;
129 tsk->thread.trap_nr = trapnr;
130 die(str, regs, error_code);
138 static void __kprobes
139 do_trap(int trapnr, int signr, char *str, struct pt_regs *regs,
140 long error_code, siginfo_t *info)
142 struct task_struct *tsk = current;
145 if (!do_trap_no_signal(tsk, trapnr, str, regs, error_code))
148 * We want error_code and trap_nr set for userspace faults and
149 * kernelspace faults which result in die(), but not
150 * kernelspace faults which are fixed up. die() gives the
151 * process no chance to handle the signal and notice the
152 * kernel fault information, so that won't result in polluting
153 * the information about previously queued, but not yet
154 * delivered, faults. See also do_general_protection below.
156 tsk->thread.error_code = error_code;
157 tsk->thread.trap_nr = trapnr;
160 if (show_unhandled_signals && unhandled_signal(tsk, signr) &&
161 printk_ratelimit()) {
162 pr_info("%s[%d] trap %s ip:%lx sp:%lx error:%lx",
163 tsk->comm, tsk->pid, str,
164 regs->ip, regs->sp, error_code);
165 print_vma_addr(" in ", regs->ip);
171 force_sig_info(signr, info, tsk);
173 force_sig(signr, tsk);
176 #define DO_ERROR(trapnr, signr, str, name) \
177 dotraplinkage void do_##name(struct pt_regs *regs, long error_code) \
179 enum ctx_state prev_state; \
181 prev_state = exception_enter(); \
182 if (notify_die(DIE_TRAP, str, regs, error_code, \
183 trapnr, signr) == NOTIFY_STOP) { \
184 exception_exit(prev_state); \
187 conditional_sti(regs); \
188 do_trap(trapnr, signr, str, regs, error_code, NULL); \
189 exception_exit(prev_state); \
192 #define DO_ERROR_INFO(trapnr, signr, str, name, sicode, siaddr) \
193 dotraplinkage void do_##name(struct pt_regs *regs, long error_code) \
196 enum ctx_state prev_state; \
198 info.si_signo = signr; \
200 info.si_code = sicode; \
201 info.si_addr = (void __user *)siaddr; \
202 prev_state = exception_enter(); \
203 if (notify_die(DIE_TRAP, str, regs, error_code, \
204 trapnr, signr) == NOTIFY_STOP) { \
205 exception_exit(prev_state); \
208 conditional_sti(regs); \
209 do_trap(trapnr, signr, str, regs, error_code, &info); \
210 exception_exit(prev_state); \
213 DO_ERROR_INFO(X86_TRAP_DE, SIGFPE, "divide error", divide_error, FPE_INTDIV,
215 DO_ERROR(X86_TRAP_OF, SIGSEGV, "overflow", overflow)
216 DO_ERROR(X86_TRAP_BR, SIGSEGV, "bounds", bounds)
217 DO_ERROR_INFO(X86_TRAP_UD, SIGILL, "invalid opcode", invalid_op, ILL_ILLOPN,
219 DO_ERROR(X86_TRAP_OLD_MF, SIGFPE, "coprocessor segment overrun",
220 coprocessor_segment_overrun)
221 DO_ERROR(X86_TRAP_TS, SIGSEGV, "invalid TSS", invalid_TSS)
222 DO_ERROR(X86_TRAP_NP, SIGBUS, "segment not present", segment_not_present)
224 DO_ERROR(X86_TRAP_SS, SIGBUS, "stack segment", stack_segment)
226 DO_ERROR_INFO(X86_TRAP_AC, SIGBUS, "alignment check", alignment_check,
230 /* Runs on IST stack */
231 dotraplinkage void do_stack_segment(struct pt_regs *regs, long error_code)
233 enum ctx_state prev_state;
235 prev_state = exception_enter();
236 if (notify_die(DIE_TRAP, "stack segment", regs, error_code,
237 X86_TRAP_SS, SIGBUS) != NOTIFY_STOP) {
238 preempt_conditional_sti(regs);
239 do_trap(X86_TRAP_SS, SIGBUS, "stack segment", regs, error_code, NULL);
240 preempt_conditional_cli(regs);
242 exception_exit(prev_state);
245 dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code)
247 static const char str[] = "double fault";
248 struct task_struct *tsk = current;
251 /* Return not checked because double check cannot be ignored */
252 notify_die(DIE_TRAP, str, regs, error_code, X86_TRAP_DF, SIGSEGV);
254 tsk->thread.error_code = error_code;
255 tsk->thread.trap_nr = X86_TRAP_DF;
258 * This is always a kernel trap and never fixable (and thus must
262 die(str, regs, error_code);
266 dotraplinkage void __kprobes
267 do_general_protection(struct pt_regs *regs, long error_code)
269 struct task_struct *tsk;
270 enum ctx_state prev_state;
272 prev_state = exception_enter();
273 conditional_sti(regs);
276 if (regs->flags & X86_VM_MASK) {
278 handle_vm86_fault((struct kernel_vm86_regs *) regs, error_code);
284 if (!user_mode(regs)) {
285 if (fixup_exception(regs))
288 tsk->thread.error_code = error_code;
289 tsk->thread.trap_nr = X86_TRAP_GP;
290 if (notify_die(DIE_GPF, "general protection fault", regs, error_code,
291 X86_TRAP_GP, SIGSEGV) != NOTIFY_STOP)
292 die("general protection fault", regs, error_code);
296 tsk->thread.error_code = error_code;
297 tsk->thread.trap_nr = X86_TRAP_GP;
299 if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) &&
300 printk_ratelimit()) {
301 pr_info("%s[%d] general protection ip:%lx sp:%lx error:%lx",
302 tsk->comm, task_pid_nr(tsk),
303 regs->ip, regs->sp, error_code);
304 print_vma_addr(" in ", regs->ip);
308 force_sig(SIGSEGV, tsk);
310 exception_exit(prev_state);
313 /* May run on IST stack. */
314 dotraplinkage void __kprobes notrace do_int3(struct pt_regs *regs, long error_code)
316 enum ctx_state prev_state;
318 #ifdef CONFIG_DYNAMIC_FTRACE
320 * ftrace must be first, everything else may cause a recursive crash.
321 * See note by declaration of modifying_ftrace_code in ftrace.c
323 if (unlikely(atomic_read(&modifying_ftrace_code)) &&
324 ftrace_int3_handler(regs))
327 prev_state = exception_enter();
328 #ifdef CONFIG_KGDB_LOW_LEVEL_TRAP
329 if (kgdb_ll_trap(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP,
330 SIGTRAP) == NOTIFY_STOP)
332 #endif /* CONFIG_KGDB_LOW_LEVEL_TRAP */
334 if (notify_die(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP,
335 SIGTRAP) == NOTIFY_STOP)
339 * Let others (NMI) know that the debug stack is in use
340 * as we may switch to the interrupt stack.
342 debug_stack_usage_inc();
343 preempt_conditional_sti(regs);
344 do_trap(X86_TRAP_BP, SIGTRAP, "int3", regs, error_code, NULL);
345 preempt_conditional_cli(regs);
346 debug_stack_usage_dec();
348 exception_exit(prev_state);
353 * Help handler running on IST stack to switch back to user stack
354 * for scheduling or signal handling. The actual stack switch is done in
357 asmlinkage __kprobes struct pt_regs *sync_regs(struct pt_regs *eregs)
359 struct pt_regs *regs = eregs;
360 /* Did already sync */
361 if (eregs == (struct pt_regs *)eregs->sp)
363 /* Exception from user space */
364 else if (user_mode(eregs))
365 regs = task_pt_regs(current);
367 * Exception from kernel and interrupts are enabled. Move to
368 * kernel process stack.
370 else if (eregs->flags & X86_EFLAGS_IF)
371 regs = (struct pt_regs *)(eregs->sp -= sizeof(struct pt_regs));
379 * Our handling of the processor debug registers is non-trivial.
380 * We do not clear them on entry and exit from the kernel. Therefore
381 * it is possible to get a watchpoint trap here from inside the kernel.
382 * However, the code in ./ptrace.c has ensured that the user can
383 * only set watchpoints on userspace addresses. Therefore the in-kernel
384 * watchpoint trap can only occur in code which is reading/writing
385 * from user space. Such code must not hold kernel locks (since it
386 * can equally take a page fault), therefore it is safe to call
387 * force_sig_info even though that claims and releases locks.
389 * Code in ./signal.c ensures that the debug control register
390 * is restored before we deliver any signal, and therefore that
391 * user code runs with the correct debug control register even though
394 * Being careful here means that we don't have to be as careful in a
395 * lot of more complicated places (task switching can be a bit lazy
396 * about restoring all the debug state, and ptrace doesn't have to
397 * find every occurrence of the TF bit that could be saved away even
400 * May run on IST stack.
402 dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code)
404 struct task_struct *tsk = current;
405 enum ctx_state prev_state;
410 prev_state = exception_enter();
412 get_debugreg(dr6, 6);
414 /* Filter out all the reserved bits which are preset to 1 */
415 dr6 &= ~DR6_RESERVED;
418 * If dr6 has no reason to give us about the origin of this trap,
419 * then it's very likely the result of an icebp/int01 trap.
420 * User wants a sigtrap for that.
422 if (!dr6 && user_mode(regs))
425 /* Catch kmemcheck conditions first of all! */
426 if ((dr6 & DR_STEP) && kmemcheck_trap(regs))
429 /* DR6 may or may not be cleared by the CPU */
433 * The processor cleared BTF, so don't mark that we need it set.
435 clear_tsk_thread_flag(tsk, TIF_BLOCKSTEP);
437 /* Store the virtualized DR6 value */
438 tsk->thread.debugreg6 = dr6;
440 if (notify_die(DIE_DEBUG, "debug", regs, PTR_ERR(&dr6), error_code,
441 SIGTRAP) == NOTIFY_STOP)
445 * Let others (NMI) know that the debug stack is in use
446 * as we may switch to the interrupt stack.
448 debug_stack_usage_inc();
450 /* It's safe to allow irq's after DR6 has been saved */
451 preempt_conditional_sti(regs);
453 if (regs->flags & X86_VM_MASK) {
454 handle_vm86_trap((struct kernel_vm86_regs *) regs, error_code,
456 preempt_conditional_cli(regs);
457 debug_stack_usage_dec();
462 * Single-stepping through system calls: ignore any exceptions in
463 * kernel space, but re-enable TF when returning to user mode.
465 * We already checked v86 mode above, so we can check for kernel mode
466 * by just checking the CPL of CS.
468 if ((dr6 & DR_STEP) && !user_mode(regs)) {
469 tsk->thread.debugreg6 &= ~DR_STEP;
470 set_tsk_thread_flag(tsk, TIF_SINGLESTEP);
471 regs->flags &= ~X86_EFLAGS_TF;
473 si_code = get_si_code(tsk->thread.debugreg6);
474 if (tsk->thread.debugreg6 & (DR_STEP | DR_TRAP_BITS) || user_icebp)
475 send_sigtrap(tsk, regs, error_code, si_code);
476 preempt_conditional_cli(regs);
477 debug_stack_usage_dec();
480 exception_exit(prev_state);
484 * Note that we play around with the 'TS' bit in an attempt to get
485 * the correct behaviour even in the presence of the asynchronous
488 void math_error(struct pt_regs *regs, int error_code, int trapnr)
490 struct task_struct *task = current;
493 char *str = (trapnr == X86_TRAP_MF) ? "fpu exception" :
496 if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, SIGFPE) == NOTIFY_STOP)
498 conditional_sti(regs);
500 if (!user_mode_vm(regs))
502 if (!fixup_exception(regs)) {
503 task->thread.error_code = error_code;
504 task->thread.trap_nr = trapnr;
505 die(str, regs, error_code);
511 * Save the info for the exception handler and clear the error.
514 task->thread.trap_nr = trapnr;
515 task->thread.error_code = error_code;
516 info.si_signo = SIGFPE;
518 info.si_addr = (void __user *)regs->ip;
519 if (trapnr == X86_TRAP_MF) {
520 unsigned short cwd, swd;
522 * (~cwd & swd) will mask out exceptions that are not set to unmasked
523 * status. 0x3f is the exception bits in these regs, 0x200 is the
524 * C1 reg you need in case of a stack fault, 0x040 is the stack
525 * fault bit. We should only be taking one exception at a time,
526 * so if this combination doesn't produce any single exception,
527 * then we have a bad program that isn't synchronizing its FPU usage
528 * and it will suffer the consequences since we won't be able to
529 * fully reproduce the context of the exception
531 cwd = get_fpu_cwd(task);
532 swd = get_fpu_swd(task);
537 * The SIMD FPU exceptions are handled a little differently, as there
538 * is only a single status/control register. Thus, to determine which
539 * unmasked exception was caught we must mask the exception mask bits
540 * at 0x1f80, and then use these to mask the exception bits at 0x3f.
542 unsigned short mxcsr = get_fpu_mxcsr(task);
543 err = ~(mxcsr >> 7) & mxcsr;
546 if (err & 0x001) { /* Invalid op */
548 * swd & 0x240 == 0x040: Stack Underflow
549 * swd & 0x240 == 0x240: Stack Overflow
550 * User must clear the SF bit (0x40) if set
552 info.si_code = FPE_FLTINV;
553 } else if (err & 0x004) { /* Divide by Zero */
554 info.si_code = FPE_FLTDIV;
555 } else if (err & 0x008) { /* Overflow */
556 info.si_code = FPE_FLTOVF;
557 } else if (err & 0x012) { /* Denormal, Underflow */
558 info.si_code = FPE_FLTUND;
559 } else if (err & 0x020) { /* Precision */
560 info.si_code = FPE_FLTRES;
563 * If we're using IRQ 13, or supposedly even some trap
564 * X86_TRAP_MF implementations, it's possible
565 * we get a spurious trap, which is not an error.
569 force_sig_info(SIGFPE, &info, task);
572 dotraplinkage void do_coprocessor_error(struct pt_regs *regs, long error_code)
574 enum ctx_state prev_state;
576 prev_state = exception_enter();
577 math_error(regs, error_code, X86_TRAP_MF);
578 exception_exit(prev_state);
582 do_simd_coprocessor_error(struct pt_regs *regs, long error_code)
584 enum ctx_state prev_state;
586 prev_state = exception_enter();
587 math_error(regs, error_code, X86_TRAP_XF);
588 exception_exit(prev_state);
592 do_spurious_interrupt_bug(struct pt_regs *regs, long error_code)
594 conditional_sti(regs);
596 /* No need to warn about this any longer. */
597 pr_info("Ignoring P6 Local APIC Spurious Interrupt Bug...\n");
601 asmlinkage void __attribute__((weak)) smp_thermal_interrupt(void)
605 asmlinkage void __attribute__((weak)) smp_threshold_interrupt(void)
610 * 'math_state_restore()' saves the current math information in the
611 * old math state array, and gets the new ones from the current task
613 * Careful.. There are problems with IBM-designed IRQ13 behaviour.
614 * Don't touch unless you *really* know how it works.
616 * Must be called with kernel preemption disabled (eg with local
617 * local interrupts as in the case of do_device_not_available).
619 void math_state_restore(void)
621 struct task_struct *tsk = current;
623 if (!tsk_used_math(tsk)) {
626 * does a slab alloc which can sleep
632 do_group_exit(SIGKILL);
638 __thread_fpu_begin(tsk);
641 * Paranoid restore. send a SIGSEGV if we fail to restore the state.
643 if (unlikely(restore_fpu_checking(tsk))) {
645 force_sig(SIGSEGV, tsk);
651 EXPORT_SYMBOL_GPL(math_state_restore);
653 dotraplinkage void __kprobes
654 do_device_not_available(struct pt_regs *regs, long error_code)
656 enum ctx_state prev_state;
658 prev_state = exception_enter();
659 BUG_ON(use_eager_fpu());
661 #ifdef CONFIG_MATH_EMULATION
662 if (read_cr0() & X86_CR0_EM) {
663 struct math_emu_info info = { };
665 conditional_sti(regs);
669 exception_exit(prev_state);
673 math_state_restore(); /* interrupts still off */
675 conditional_sti(regs);
677 exception_exit(prev_state);
681 dotraplinkage void do_iret_error(struct pt_regs *regs, long error_code)
684 enum ctx_state prev_state;
686 prev_state = exception_enter();
689 info.si_signo = SIGILL;
691 info.si_code = ILL_BADSTK;
693 if (notify_die(DIE_TRAP, "iret exception", regs, error_code,
694 X86_TRAP_IRET, SIGILL) != NOTIFY_STOP) {
695 do_trap(X86_TRAP_IRET, SIGILL, "iret exception", regs, error_code,
698 exception_exit(prev_state);
702 /* Set of traps needed for early debugging. */
703 void __init early_trap_init(void)
705 set_intr_gate_ist(X86_TRAP_DB, &debug, DEBUG_STACK);
706 /* int3 can be called from all */
707 set_system_intr_gate_ist(X86_TRAP_BP, &int3, DEBUG_STACK);
709 set_intr_gate(X86_TRAP_PF, &page_fault);
711 load_idt(&idt_descr);
714 void __init early_trap_pf_init(void)
717 set_intr_gate(X86_TRAP_PF, &page_fault);
721 void __init trap_init(void)
726 void __iomem *p = early_ioremap(0x0FFFD9, 4);
728 if (readl(p) == 'E' + ('I'<<8) + ('S'<<16) + ('A'<<24))
733 set_intr_gate(X86_TRAP_DE, ÷_error);
734 set_intr_gate_ist(X86_TRAP_NMI, &nmi, NMI_STACK);
735 /* int4 can be called from all */
736 set_system_intr_gate(X86_TRAP_OF, &overflow);
737 set_intr_gate(X86_TRAP_BR, &bounds);
738 set_intr_gate(X86_TRAP_UD, &invalid_op);
739 set_intr_gate(X86_TRAP_NM, &device_not_available);
741 set_task_gate(X86_TRAP_DF, GDT_ENTRY_DOUBLEFAULT_TSS);
743 set_intr_gate_ist(X86_TRAP_DF, &double_fault, DOUBLEFAULT_STACK);
745 set_intr_gate(X86_TRAP_OLD_MF, &coprocessor_segment_overrun);
746 set_intr_gate(X86_TRAP_TS, &invalid_TSS);
747 set_intr_gate(X86_TRAP_NP, &segment_not_present);
748 set_intr_gate_ist(X86_TRAP_SS, &stack_segment, STACKFAULT_STACK);
749 set_intr_gate(X86_TRAP_GP, &general_protection);
750 set_intr_gate(X86_TRAP_SPURIOUS, &spurious_interrupt_bug);
751 set_intr_gate(X86_TRAP_MF, &coprocessor_error);
752 set_intr_gate(X86_TRAP_AC, &alignment_check);
753 #ifdef CONFIG_X86_MCE
754 set_intr_gate_ist(X86_TRAP_MC, &machine_check, MCE_STACK);
756 set_intr_gate(X86_TRAP_XF, &simd_coprocessor_error);
758 /* Reserve all the builtin and the syscall vector: */
759 for (i = 0; i < FIRST_EXTERNAL_VECTOR; i++)
760 set_bit(i, used_vectors);
762 #ifdef CONFIG_IA32_EMULATION
763 set_system_intr_gate(IA32_SYSCALL_VECTOR, ia32_syscall);
764 set_bit(IA32_SYSCALL_VECTOR, used_vectors);
768 set_system_trap_gate(SYSCALL_VECTOR, &system_call);
769 set_bit(SYSCALL_VECTOR, used_vectors);
773 * Set the IDT descriptor to a fixed read-only location, so that the
774 * "sidt" instruction will not leak the location of the kernel, and
775 * to defend the IDT against arbitrary memory write vulnerabilities.
776 * It will be reloaded in cpu_init() */
777 __set_fixmap(FIX_RO_IDT, __pa_symbol(idt_table), PAGE_KERNEL_RO);
778 idt_descr.address = fix_to_virt(FIX_RO_IDT);
781 * Should be a barrier for any external CPU state:
785 x86_init.irqs.trap_init();
788 memcpy(&nmi_idt_table, &idt_table, IDT_ENTRIES * 16);
789 set_nmi_gate(X86_TRAP_DB, &debug);
790 set_nmi_gate(X86_TRAP_BP, &int3);