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1/*
2 * Copyright (C) 1991, 1992 Linus Torvalds
3 * Copyright (C) 2000, 2001, 2002 Andi Kleen, SuSE Labs
4 *
5 * Pentium III FXSR, SSE support
6 * Gareth Hughes <gareth@valinux.com>, May 2000
7 */
8
9/*
10 * Handle hardware traps and faults.
11 */
12
13#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
14
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>
37#include <linux/mm.h>
38#include <linux/smp.h>
39#include <linux/io.h>
40
41#if defined(CONFIG_EDAC)
42#include <linux/edac.h>
43#endif
44
45#include <asm/stacktrace.h>
46#include <asm/processor.h>
47#include <asm/debugreg.h>
48#include <linux/atomic.h>
49#include <asm/text-patching.h>
50#include <asm/ftrace.h>
51#include <asm/traps.h>
52#include <asm/desc.h>
53#include <asm/fpu/internal.h>
54#include <asm/cpu_entry_area.h>
55#include <asm/mce.h>
56#include <asm/fixmap.h>
57#include <asm/mach_traps.h>
58#include <asm/alternative.h>
59#include <asm/fpu/xstate.h>
60#include <asm/trace/mpx.h>
61#include <asm/mpx.h>
62#include <asm/vm86.h>
63#include <asm/umip.h>
64
65#ifdef CONFIG_X86_64
66#include <asm/x86_init.h>
67#include <asm/pgalloc.h>
68#include <asm/proto.h>
69#else
70#include <asm/processor-flags.h>
71#include <asm/setup.h>
72#include <asm/proto.h>
73#endif
74
75DECLARE_BITMAP(system_vectors, NR_VECTORS);
76
77static inline void cond_local_irq_enable(struct pt_regs *regs)
78{
79 if (regs->flags & X86_EFLAGS_IF)
80 local_irq_enable();
81}
82
83static inline void cond_local_irq_disable(struct pt_regs *regs)
84{
85 if (regs->flags & X86_EFLAGS_IF)
86 local_irq_disable();
87}
88
89/*
90 * In IST context, we explicitly disable preemption. This serves two
91 * purposes: it makes it much less likely that we would accidentally
92 * schedule in IST context and it will force a warning if we somehow
93 * manage to schedule by accident.
94 */
95void ist_enter(struct pt_regs *regs)
96{
97 if (user_mode(regs)) {
98 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
99 } else {
100 /*
101 * We might have interrupted pretty much anything. In
102 * fact, if we're a machine check, we can even interrupt
103 * NMI processing. We don't want in_nmi() to return true,
104 * but we need to notify RCU.
105 */
106 rcu_nmi_enter();
107 }
108
109 preempt_disable();
110
111 /* This code is a bit fragile. Test it. */
112 RCU_LOCKDEP_WARN(!rcu_is_watching(), "ist_enter didn't work");
113}
114
115void ist_exit(struct pt_regs *regs)
116{
117 preempt_enable_no_resched();
118
119 if (!user_mode(regs))
120 rcu_nmi_exit();
121}
122
123/**
124 * ist_begin_non_atomic() - begin a non-atomic section in an IST exception
125 * @regs: regs passed to the IST exception handler
126 *
127 * IST exception handlers normally cannot schedule. As a special
128 * exception, if the exception interrupted userspace code (i.e.
129 * user_mode(regs) would return true) and the exception was not
130 * a double fault, it can be safe to schedule. ist_begin_non_atomic()
131 * begins a non-atomic section within an ist_enter()/ist_exit() region.
132 * Callers are responsible for enabling interrupts themselves inside
133 * the non-atomic section, and callers must call ist_end_non_atomic()
134 * before ist_exit().
135 */
136void ist_begin_non_atomic(struct pt_regs *regs)
137{
138 BUG_ON(!user_mode(regs));
139
140 /*
141 * Sanity check: we need to be on the normal thread stack. This
142 * will catch asm bugs and any attempt to use ist_preempt_enable
143 * from double_fault.
144 */
145 BUG_ON(!on_thread_stack());
146
147 preempt_enable_no_resched();
148}
149
150/**
151 * ist_end_non_atomic() - begin a non-atomic section in an IST exception
152 *
153 * Ends a non-atomic section started with ist_begin_non_atomic().
154 */
155void ist_end_non_atomic(void)
156{
157 preempt_disable();
158}
159
160int is_valid_bugaddr(unsigned long addr)
161{
162 unsigned short ud;
163
164 if (addr < TASK_SIZE_MAX)
165 return 0;
166
167 if (probe_kernel_address((unsigned short *)addr, ud))
168 return 0;
169
170 return ud == INSN_UD0 || ud == INSN_UD2;
171}
172
173int fixup_bug(struct pt_regs *regs, int trapnr)
174{
175 if (trapnr != X86_TRAP_UD)
176 return 0;
177
178 switch (report_bug(regs->ip, regs)) {
179 case BUG_TRAP_TYPE_NONE:
180 case BUG_TRAP_TYPE_BUG:
181 break;
182
183 case BUG_TRAP_TYPE_WARN:
184 regs->ip += LEN_UD2;
185 return 1;
186 }
187
188 return 0;
189}
190
191static nokprobe_inline int
192do_trap_no_signal(struct task_struct *tsk, int trapnr, char *str,
193 struct pt_regs *regs, long error_code)
194{
195 if (v8086_mode(regs)) {
196 /*
197 * Traps 0, 1, 3, 4, and 5 should be forwarded to vm86.
198 * On nmi (interrupt 2), do_trap should not be called.
199 */
200 if (trapnr < X86_TRAP_UD) {
201 if (!handle_vm86_trap((struct kernel_vm86_regs *) regs,
202 error_code, trapnr))
203 return 0;
204 }
205 return -1;
206 }
207
208 if (!user_mode(regs)) {
209 if (fixup_exception(regs, trapnr))
210 return 0;
211
212 tsk->thread.error_code = error_code;
213 tsk->thread.trap_nr = trapnr;
214 die(str, regs, error_code);
215 }
216
217 return -1;
218}
219
220static siginfo_t *fill_trap_info(struct pt_regs *regs, int signr, int trapnr,
221 siginfo_t *info)
222{
223 unsigned long siaddr;
224 int sicode;
225
226 switch (trapnr) {
227 default:
228 return SEND_SIG_PRIV;
229
230 case X86_TRAP_DE:
231 sicode = FPE_INTDIV;
232 siaddr = uprobe_get_trap_addr(regs);
233 break;
234 case X86_TRAP_UD:
235 sicode = ILL_ILLOPN;
236 siaddr = uprobe_get_trap_addr(regs);
237 break;
238 case X86_TRAP_AC:
239 sicode = BUS_ADRALN;
240 siaddr = 0;
241 break;
242 }
243
244 info->si_signo = signr;
245 info->si_errno = 0;
246 info->si_code = sicode;
247 info->si_addr = (void __user *)siaddr;
248 return info;
249}
250
251static void
252do_trap(int trapnr, int signr, char *str, struct pt_regs *regs,
253 long error_code, siginfo_t *info)
254{
255 struct task_struct *tsk = current;
256
257
258 if (!do_trap_no_signal(tsk, trapnr, str, regs, error_code))
259 return;
260 /*
261 * We want error_code and trap_nr set for userspace faults and
262 * kernelspace faults which result in die(), but not
263 * kernelspace faults which are fixed up. die() gives the
264 * process no chance to handle the signal and notice the
265 * kernel fault information, so that won't result in polluting
266 * the information about previously queued, but not yet
267 * delivered, faults. See also do_general_protection below.
268 */
269 tsk->thread.error_code = error_code;
270 tsk->thread.trap_nr = trapnr;
271
272 if (show_unhandled_signals && unhandled_signal(tsk, signr) &&
273 printk_ratelimit()) {
274 pr_info("%s[%d] trap %s ip:%lx sp:%lx error:%lx",
275 tsk->comm, tsk->pid, str,
276 regs->ip, regs->sp, error_code);
277 print_vma_addr(KERN_CONT " in ", regs->ip);
278 pr_cont("\n");
279 }
280
281 force_sig_info(signr, info ?: SEND_SIG_PRIV, tsk);
282}
283NOKPROBE_SYMBOL(do_trap);
284
285static void do_error_trap(struct pt_regs *regs, long error_code, char *str,
286 unsigned long trapnr, int signr)
287{
288 siginfo_t info;
289
290 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
291
292 /*
293 * WARN*()s end up here; fix them up before we call the
294 * notifier chain.
295 */
296 if (!user_mode(regs) && fixup_bug(regs, trapnr))
297 return;
298
299 if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) !=
300 NOTIFY_STOP) {
301 cond_local_irq_enable(regs);
302 do_trap(trapnr, signr, str, regs, error_code,
303 fill_trap_info(regs, signr, trapnr, &info));
304 }
305}
306
307#define DO_ERROR(trapnr, signr, str, name) \
308dotraplinkage void do_##name(struct pt_regs *regs, long error_code) \
309{ \
310 do_error_trap(regs, error_code, str, trapnr, signr); \
311}
312
313DO_ERROR(X86_TRAP_DE, SIGFPE, "divide error", divide_error)
314DO_ERROR(X86_TRAP_OF, SIGSEGV, "overflow", overflow)
315DO_ERROR(X86_TRAP_UD, SIGILL, "invalid opcode", invalid_op)
316DO_ERROR(X86_TRAP_OLD_MF, SIGFPE, "coprocessor segment overrun",coprocessor_segment_overrun)
317DO_ERROR(X86_TRAP_TS, SIGSEGV, "invalid TSS", invalid_TSS)
318DO_ERROR(X86_TRAP_NP, SIGBUS, "segment not present", segment_not_present)
319DO_ERROR(X86_TRAP_SS, SIGBUS, "stack segment", stack_segment)
320DO_ERROR(X86_TRAP_AC, SIGBUS, "alignment check", alignment_check)
321
322#ifdef CONFIG_VMAP_STACK
323__visible void __noreturn handle_stack_overflow(const char *message,
324 struct pt_regs *regs,
325 unsigned long fault_address)
326{
327 printk(KERN_EMERG "BUG: stack guard page was hit at %p (stack is %p..%p)\n",
328 (void *)fault_address, current->stack,
329 (char *)current->stack + THREAD_SIZE - 1);
330 die(message, regs, 0);
331
332 /* Be absolutely certain we don't return. */
333 panic(message);
334}
335#endif
336
337#ifdef CONFIG_X86_64
338/* Runs on IST stack */
339dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code)
340{
341 static const char str[] = "double fault";
342 struct task_struct *tsk = current;
343#ifdef CONFIG_VMAP_STACK
344 unsigned long cr2;
345#endif
346
347#ifdef CONFIG_X86_ESPFIX64
348 extern unsigned char native_irq_return_iret[];
349
350 /*
351 * If IRET takes a non-IST fault on the espfix64 stack, then we
352 * end up promoting it to a doublefault. In that case, take
353 * advantage of the fact that we're not using the normal (TSS.sp0)
354 * stack right now. We can write a fake #GP(0) frame at TSS.sp0
355 * and then modify our own IRET frame so that, when we return,
356 * we land directly at the #GP(0) vector with the stack already
357 * set up according to its expectations.
358 *
359 * The net result is that our #GP handler will think that we
360 * entered from usermode with the bad user context.
361 *
362 * No need for ist_enter here because we don't use RCU.
363 */
364 if (((long)regs->sp >> P4D_SHIFT) == ESPFIX_PGD_ENTRY &&
365 regs->cs == __KERNEL_CS &&
366 regs->ip == (unsigned long)native_irq_return_iret)
367 {
368 struct pt_regs *gpregs = (struct pt_regs *)this_cpu_read(cpu_tss_rw.x86_tss.sp0) - 1;
369
370 /*
371 * regs->sp points to the failing IRET frame on the
372 * ESPFIX64 stack. Copy it to the entry stack. This fills
373 * in gpregs->ss through gpregs->ip.
374 *
375 */
376 memmove(&gpregs->ip, (void *)regs->sp, 5*8);
377 gpregs->orig_ax = 0; /* Missing (lost) #GP error code */
378
379 /*
380 * Adjust our frame so that we return straight to the #GP
381 * vector with the expected RSP value. This is safe because
382 * we won't enable interupts or schedule before we invoke
383 * general_protection, so nothing will clobber the stack
384 * frame we just set up.
385 */
386 regs->ip = (unsigned long)general_protection;
387 regs->sp = (unsigned long)&gpregs->orig_ax;
388
389 return;
390 }
391#endif
392
393 ist_enter(regs);
394 notify_die(DIE_TRAP, str, regs, error_code, X86_TRAP_DF, SIGSEGV);
395
396 tsk->thread.error_code = error_code;
397 tsk->thread.trap_nr = X86_TRAP_DF;
398
399#ifdef CONFIG_VMAP_STACK
400 /*
401 * If we overflow the stack into a guard page, the CPU will fail
402 * to deliver #PF and will send #DF instead. Similarly, if we
403 * take any non-IST exception while too close to the bottom of
404 * the stack, the processor will get a page fault while
405 * delivering the exception and will generate a double fault.
406 *
407 * According to the SDM (footnote in 6.15 under "Interrupt 14 -
408 * Page-Fault Exception (#PF):
409 *
410 * Processors update CR2 whenever a page fault is detected. If a
411 * second page fault occurs while an earlier page fault is being
412 * delivered, the faulting linear address of the second fault will
413 * overwrite the contents of CR2 (replacing the previous
414 * address). These updates to CR2 occur even if the page fault
415 * results in a double fault or occurs during the delivery of a
416 * double fault.
417 *
418 * The logic below has a small possibility of incorrectly diagnosing
419 * some errors as stack overflows. For example, if the IDT or GDT
420 * gets corrupted such that #GP delivery fails due to a bad descriptor
421 * causing #GP and we hit this condition while CR2 coincidentally
422 * points to the stack guard page, we'll think we overflowed the
423 * stack. Given that we're going to panic one way or another
424 * if this happens, this isn't necessarily worth fixing.
425 *
426 * If necessary, we could improve the test by only diagnosing
427 * a stack overflow if the saved RSP points within 47 bytes of
428 * the bottom of the stack: if RSP == tsk_stack + 48 and we
429 * take an exception, the stack is already aligned and there
430 * will be enough room SS, RSP, RFLAGS, CS, RIP, and a
431 * possible error code, so a stack overflow would *not* double
432 * fault. With any less space left, exception delivery could
433 * fail, and, as a practical matter, we've overflowed the
434 * stack even if the actual trigger for the double fault was
435 * something else.
436 */
437 cr2 = read_cr2();
438 if ((unsigned long)task_stack_page(tsk) - 1 - cr2 < PAGE_SIZE)
439 handle_stack_overflow("kernel stack overflow (double-fault)", regs, cr2);
440#endif
441
442#ifdef CONFIG_DOUBLEFAULT
443 df_debug(regs, error_code);
444#endif
445 /*
446 * This is always a kernel trap and never fixable (and thus must
447 * never return).
448 */
449 for (;;)
450 die(str, regs, error_code);
451}
452#endif
453
454dotraplinkage void do_bounds(struct pt_regs *regs, long error_code)
455{
456 const struct mpx_bndcsr *bndcsr;
457 siginfo_t *info;
458
459 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
460 if (notify_die(DIE_TRAP, "bounds", regs, error_code,
461 X86_TRAP_BR, SIGSEGV) == NOTIFY_STOP)
462 return;
463 cond_local_irq_enable(regs);
464
465 if (!user_mode(regs))
466 die("bounds", regs, error_code);
467
468 if (!cpu_feature_enabled(X86_FEATURE_MPX)) {
469 /* The exception is not from Intel MPX */
470 goto exit_trap;
471 }
472
473 /*
474 * We need to look at BNDSTATUS to resolve this exception.
475 * A NULL here might mean that it is in its 'init state',
476 * which is all zeros which indicates MPX was not
477 * responsible for the exception.
478 */
479 bndcsr = get_xsave_field_ptr(XFEATURE_MASK_BNDCSR);
480 if (!bndcsr)
481 goto exit_trap;
482
483 trace_bounds_exception_mpx(bndcsr);
484 /*
485 * The error code field of the BNDSTATUS register communicates status
486 * information of a bound range exception #BR or operation involving
487 * bound directory.
488 */
489 switch (bndcsr->bndstatus & MPX_BNDSTA_ERROR_CODE) {
490 case 2: /* Bound directory has invalid entry. */
491 if (mpx_handle_bd_fault())
492 goto exit_trap;
493 break; /* Success, it was handled */
494 case 1: /* Bound violation. */
495 info = mpx_generate_siginfo(regs);
496 if (IS_ERR(info)) {
497 /*
498 * We failed to decode the MPX instruction. Act as if
499 * the exception was not caused by MPX.
500 */
501 goto exit_trap;
502 }
503 /*
504 * Success, we decoded the instruction and retrieved
505 * an 'info' containing the address being accessed
506 * which caused the exception. This information
507 * allows and application to possibly handle the
508 * #BR exception itself.
509 */
510 do_trap(X86_TRAP_BR, SIGSEGV, "bounds", regs, error_code, info);
511 kfree(info);
512 break;
513 case 0: /* No exception caused by Intel MPX operations. */
514 goto exit_trap;
515 default:
516 die("bounds", regs, error_code);
517 }
518
519 return;
520
521exit_trap:
522 /*
523 * This path out is for all the cases where we could not
524 * handle the exception in some way (like allocating a
525 * table or telling userspace about it. We will also end
526 * up here if the kernel has MPX turned off at compile
527 * time..
528 */
529 do_trap(X86_TRAP_BR, SIGSEGV, "bounds", regs, error_code, NULL);
530}
531
532dotraplinkage void
533do_general_protection(struct pt_regs *regs, long error_code)
534{
535 struct task_struct *tsk;
536
537 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
538 cond_local_irq_enable(regs);
539
540 if (static_cpu_has(X86_FEATURE_UMIP)) {
541 if (user_mode(regs) && fixup_umip_exception(regs))
542 return;
543 }
544
545 if (v8086_mode(regs)) {
546 local_irq_enable();
547 handle_vm86_fault((struct kernel_vm86_regs *) regs, error_code);
548 return;
549 }
550
551 tsk = current;
552 if (!user_mode(regs)) {
553 if (fixup_exception(regs, X86_TRAP_GP))
554 return;
555
556 tsk->thread.error_code = error_code;
557 tsk->thread.trap_nr = X86_TRAP_GP;
558 if (notify_die(DIE_GPF, "general protection fault", regs, error_code,
559 X86_TRAP_GP, SIGSEGV) != NOTIFY_STOP)
560 die("general protection fault", regs, error_code);
561 return;
562 }
563
564 tsk->thread.error_code = error_code;
565 tsk->thread.trap_nr = X86_TRAP_GP;
566
567 if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) &&
568 printk_ratelimit()) {
569 pr_info("%s[%d] general protection ip:%lx sp:%lx error:%lx",
570 tsk->comm, task_pid_nr(tsk),
571 regs->ip, regs->sp, error_code);
572 print_vma_addr(KERN_CONT " in ", regs->ip);
573 pr_cont("\n");
574 }
575
576 force_sig_info(SIGSEGV, SEND_SIG_PRIV, tsk);
577}
578NOKPROBE_SYMBOL(do_general_protection);
579
580dotraplinkage void notrace do_int3(struct pt_regs *regs, long error_code)
581{
582#ifdef CONFIG_DYNAMIC_FTRACE
583 /*
584 * ftrace must be first, everything else may cause a recursive crash.
585 * See note by declaration of modifying_ftrace_code in ftrace.c
586 */
587 if (unlikely(atomic_read(&modifying_ftrace_code)) &&
588 ftrace_int3_handler(regs))
589 return;
590#endif
591 if (poke_int3_handler(regs))
592 return;
593
594 /*
595 * Use ist_enter despite the fact that we don't use an IST stack.
596 * We can be called from a kprobe in non-CONTEXT_KERNEL kernel
597 * mode or even during context tracking state changes.
598 *
599 * This means that we can't schedule. That's okay.
600 */
601 ist_enter(regs);
602 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
603#ifdef CONFIG_KGDB_LOW_LEVEL_TRAP
604 if (kgdb_ll_trap(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP,
605 SIGTRAP) == NOTIFY_STOP)
606 goto exit;
607#endif /* CONFIG_KGDB_LOW_LEVEL_TRAP */
608
609#ifdef CONFIG_KPROBES
610 if (kprobe_int3_handler(regs))
611 goto exit;
612#endif
613
614 if (notify_die(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP,
615 SIGTRAP) == NOTIFY_STOP)
616 goto exit;
617
618 cond_local_irq_enable(regs);
619 do_trap(X86_TRAP_BP, SIGTRAP, "int3", regs, error_code, NULL);
620 cond_local_irq_disable(regs);
621
622exit:
623 ist_exit(regs);
624}
625NOKPROBE_SYMBOL(do_int3);
626
627#ifdef CONFIG_X86_64
628/*
629 * Help handler running on a per-cpu (IST or entry trampoline) stack
630 * to switch to the normal thread stack if the interrupted code was in
631 * user mode. The actual stack switch is done in entry_64.S
632 */
633asmlinkage __visible notrace struct pt_regs *sync_regs(struct pt_regs *eregs)
634{
635 struct pt_regs *regs = (struct pt_regs *)this_cpu_read(cpu_current_top_of_stack) - 1;
636 if (regs != eregs)
637 *regs = *eregs;
638 return regs;
639}
640NOKPROBE_SYMBOL(sync_regs);
641
642struct bad_iret_stack {
643 void *error_entry_ret;
644 struct pt_regs regs;
645};
646
647asmlinkage __visible notrace
648struct bad_iret_stack *fixup_bad_iret(struct bad_iret_stack *s)
649{
650 /*
651 * This is called from entry_64.S early in handling a fault
652 * caused by a bad iret to user mode. To handle the fault
653 * correctly, we want to move our stack frame to where it would
654 * be had we entered directly on the entry stack (rather than
655 * just below the IRET frame) and we want to pretend that the
656 * exception came from the IRET target.
657 */
658 struct bad_iret_stack *new_stack =
659 (struct bad_iret_stack *)this_cpu_read(cpu_tss_rw.x86_tss.sp0) - 1;
660
661 /* Copy the IRET target to the new stack. */
662 memmove(&new_stack->regs.ip, (void *)s->regs.sp, 5*8);
663
664 /* Copy the remainder of the stack from the current stack. */
665 memmove(new_stack, s, offsetof(struct bad_iret_stack, regs.ip));
666
667 BUG_ON(!user_mode(&new_stack->regs));
668 return new_stack;
669}
670NOKPROBE_SYMBOL(fixup_bad_iret);
671#endif
672
673static bool is_sysenter_singlestep(struct pt_regs *regs)
674{
675 /*
676 * We don't try for precision here. If we're anywhere in the region of
677 * code that can be single-stepped in the SYSENTER entry path, then
678 * assume that this is a useless single-step trap due to SYSENTER
679 * being invoked with TF set. (We don't know in advance exactly
680 * which instructions will be hit because BTF could plausibly
681 * be set.)
682 */
683#ifdef CONFIG_X86_32
684 return (regs->ip - (unsigned long)__begin_SYSENTER_singlestep_region) <
685 (unsigned long)__end_SYSENTER_singlestep_region -
686 (unsigned long)__begin_SYSENTER_singlestep_region;
687#elif defined(CONFIG_IA32_EMULATION)
688 return (regs->ip - (unsigned long)entry_SYSENTER_compat) <
689 (unsigned long)__end_entry_SYSENTER_compat -
690 (unsigned long)entry_SYSENTER_compat;
691#else
692 return false;
693#endif
694}
695
696/*
697 * Our handling of the processor debug registers is non-trivial.
698 * We do not clear them on entry and exit from the kernel. Therefore
699 * it is possible to get a watchpoint trap here from inside the kernel.
700 * However, the code in ./ptrace.c has ensured that the user can
701 * only set watchpoints on userspace addresses. Therefore the in-kernel
702 * watchpoint trap can only occur in code which is reading/writing
703 * from user space. Such code must not hold kernel locks (since it
704 * can equally take a page fault), therefore it is safe to call
705 * force_sig_info even though that claims and releases locks.
706 *
707 * Code in ./signal.c ensures that the debug control register
708 * is restored before we deliver any signal, and therefore that
709 * user code runs with the correct debug control register even though
710 * we clear it here.
711 *
712 * Being careful here means that we don't have to be as careful in a
713 * lot of more complicated places (task switching can be a bit lazy
714 * about restoring all the debug state, and ptrace doesn't have to
715 * find every occurrence of the TF bit that could be saved away even
716 * by user code)
717 *
718 * May run on IST stack.
719 */
720dotraplinkage void do_debug(struct pt_regs *regs, long error_code)
721{
722 struct task_struct *tsk = current;
723 int user_icebp = 0;
724 unsigned long dr6;
725 int si_code;
726
727 ist_enter(regs);
728
729 get_debugreg(dr6, 6);
730 /*
731 * The Intel SDM says:
732 *
733 * Certain debug exceptions may clear bits 0-3. The remaining
734 * contents of the DR6 register are never cleared by the
735 * processor. To avoid confusion in identifying debug
736 * exceptions, debug handlers should clear the register before
737 * returning to the interrupted task.
738 *
739 * Keep it simple: clear DR6 immediately.
740 */
741 set_debugreg(0, 6);
742
743 /* Filter out all the reserved bits which are preset to 1 */
744 dr6 &= ~DR6_RESERVED;
745
746 /*
747 * The SDM says "The processor clears the BTF flag when it
748 * generates a debug exception." Clear TIF_BLOCKSTEP to keep
749 * TIF_BLOCKSTEP in sync with the hardware BTF flag.
750 */
751 clear_tsk_thread_flag(tsk, TIF_BLOCKSTEP);
752
753 if (unlikely(!user_mode(regs) && (dr6 & DR_STEP) &&
754 is_sysenter_singlestep(regs))) {
755 dr6 &= ~DR_STEP;
756 if (!dr6)
757 goto exit;
758 /*
759 * else we might have gotten a single-step trap and hit a
760 * watchpoint at the same time, in which case we should fall
761 * through and handle the watchpoint.
762 */
763 }
764
765 /*
766 * If dr6 has no reason to give us about the origin of this trap,
767 * then it's very likely the result of an icebp/int01 trap.
768 * User wants a sigtrap for that.
769 */
770 if (!dr6 && user_mode(regs))
771 user_icebp = 1;
772
773 /* Store the virtualized DR6 value */
774 tsk->thread.debugreg6 = dr6;
775
776#ifdef CONFIG_KPROBES
777 if (kprobe_debug_handler(regs))
778 goto exit;
779#endif
780
781 if (notify_die(DIE_DEBUG, "debug", regs, (long)&dr6, error_code,
782 SIGTRAP) == NOTIFY_STOP)
783 goto exit;
784
785 /*
786 * Let others (NMI) know that the debug stack is in use
787 * as we may switch to the interrupt stack.
788 */
789 debug_stack_usage_inc();
790
791 /* It's safe to allow irq's after DR6 has been saved */
792 cond_local_irq_enable(regs);
793
794 if (v8086_mode(regs)) {
795 handle_vm86_trap((struct kernel_vm86_regs *) regs, error_code,
796 X86_TRAP_DB);
797 cond_local_irq_disable(regs);
798 debug_stack_usage_dec();
799 goto exit;
800 }
801
802 if (WARN_ON_ONCE((dr6 & DR_STEP) && !user_mode(regs))) {
803 /*
804 * Historical junk that used to handle SYSENTER single-stepping.
805 * This should be unreachable now. If we survive for a while
806 * without anyone hitting this warning, we'll turn this into
807 * an oops.
808 */
809 tsk->thread.debugreg6 &= ~DR_STEP;
810 set_tsk_thread_flag(tsk, TIF_SINGLESTEP);
811 regs->flags &= ~X86_EFLAGS_TF;
812 }
813 si_code = get_si_code(tsk->thread.debugreg6);
814 if (tsk->thread.debugreg6 & (DR_STEP | DR_TRAP_BITS) || user_icebp)
815 send_sigtrap(tsk, regs, error_code, si_code);
816 cond_local_irq_disable(regs);
817 debug_stack_usage_dec();
818
819exit:
820 ist_exit(regs);
821}
822NOKPROBE_SYMBOL(do_debug);
823
824/*
825 * Note that we play around with the 'TS' bit in an attempt to get
826 * the correct behaviour even in the presence of the asynchronous
827 * IRQ13 behaviour
828 */
829static void math_error(struct pt_regs *regs, int error_code, int trapnr)
830{
831 struct task_struct *task = current;
832 struct fpu *fpu = &task->thread.fpu;
833 siginfo_t info;
834 char *str = (trapnr == X86_TRAP_MF) ? "fpu exception" :
835 "simd exception";
836
837 if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, SIGFPE) == NOTIFY_STOP)
838 return;
839 cond_local_irq_enable(regs);
840
841 if (!user_mode(regs)) {
842 if (!fixup_exception(regs, trapnr)) {
843 task->thread.error_code = error_code;
844 task->thread.trap_nr = trapnr;
845 die(str, regs, error_code);
846 }
847 return;
848 }
849
850 /*
851 * Save the info for the exception handler and clear the error.
852 */
853 fpu__save(fpu);
854
855 task->thread.trap_nr = trapnr;
856 task->thread.error_code = error_code;
857 info.si_signo = SIGFPE;
858 info.si_errno = 0;
859 info.si_addr = (void __user *)uprobe_get_trap_addr(regs);
860
861 info.si_code = fpu__exception_code(fpu, trapnr);
862
863 /* Retry when we get spurious exceptions: */
864 if (!info.si_code)
865 return;
866
867 force_sig_info(SIGFPE, &info, task);
868}
869
870dotraplinkage void do_coprocessor_error(struct pt_regs *regs, long error_code)
871{
872 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
873 math_error(regs, error_code, X86_TRAP_MF);
874}
875
876dotraplinkage void
877do_simd_coprocessor_error(struct pt_regs *regs, long error_code)
878{
879 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
880 math_error(regs, error_code, X86_TRAP_XF);
881}
882
883dotraplinkage void
884do_spurious_interrupt_bug(struct pt_regs *regs, long error_code)
885{
886 cond_local_irq_enable(regs);
887}
888
889dotraplinkage void
890do_device_not_available(struct pt_regs *regs, long error_code)
891{
892 unsigned long cr0;
893
894 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
895
896#ifdef CONFIG_MATH_EMULATION
897 if (!boot_cpu_has(X86_FEATURE_FPU) && (read_cr0() & X86_CR0_EM)) {
898 struct math_emu_info info = { };
899
900 cond_local_irq_enable(regs);
901
902 info.regs = regs;
903 math_emulate(&info);
904 return;
905 }
906#endif
907
908 /* This should not happen. */
909 cr0 = read_cr0();
910 if (WARN(cr0 & X86_CR0_TS, "CR0.TS was set")) {
911 /* Try to fix it up and carry on. */
912 write_cr0(cr0 & ~X86_CR0_TS);
913 } else {
914 /*
915 * Something terrible happened, and we're better off trying
916 * to kill the task than getting stuck in a never-ending
917 * loop of #NM faults.
918 */
919 die("unexpected #NM exception", regs, error_code);
920 }
921}
922NOKPROBE_SYMBOL(do_device_not_available);
923
924#ifdef CONFIG_X86_32
925dotraplinkage void do_iret_error(struct pt_regs *regs, long error_code)
926{
927 siginfo_t info;
928
929 RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
930 local_irq_enable();
931
932 info.si_signo = SIGILL;
933 info.si_errno = 0;
934 info.si_code = ILL_BADSTK;
935 info.si_addr = NULL;
936 if (notify_die(DIE_TRAP, "iret exception", regs, error_code,
937 X86_TRAP_IRET, SIGILL) != NOTIFY_STOP) {
938 do_trap(X86_TRAP_IRET, SIGILL, "iret exception", regs, error_code,
939 &info);
940 }
941}
942#endif
943
944void __init trap_init(void)
945{
946 /* Init cpu_entry_area before IST entries are set up */
947 setup_cpu_entry_areas();
948
949 idt_setup_traps();
950
951 /*
952 * Set the IDT descriptor to a fixed read-only location, so that the
953 * "sidt" instruction will not leak the location of the kernel, and
954 * to defend the IDT against arbitrary memory write vulnerabilities.
955 * It will be reloaded in cpu_init() */
956 cea_set_pte(CPU_ENTRY_AREA_RO_IDT_VADDR, __pa_symbol(idt_table),
957 PAGE_KERNEL_RO);
958 idt_descr.address = CPU_ENTRY_AREA_RO_IDT;
959
960 /*
961 * Should be a barrier for any external CPU state:
962 */
963 cpu_init();
964
965 idt_setup_ist_traps();
966
967 x86_init.irqs.trap_init();
968
969 idt_setup_debugidt_traps();
970}
1/*
2 * Copyright (C) 1991, 1992 Linus Torvalds
3 * Copyright (C) 2000, 2001, 2002 Andi Kleen, SuSE Labs
4 *
5 * Pentium III FXSR, SSE support
6 * Gareth Hughes <gareth@valinux.com>, May 2000
7 */
8
9/*
10 * Handle hardware traps and faults.
11 */
12
13#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
14
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>
35#include <linux/mm.h>
36#include <linux/smp.h>
37#include <linux/io.h>
38
39#ifdef CONFIG_EISA
40#include <linux/ioport.h>
41#include <linux/eisa.h>
42#endif
43
44#if defined(CONFIG_EDAC)
45#include <linux/edac.h>
46#endif
47
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>
55#include <asm/desc.h>
56#include <asm/i387.h>
57#include <asm/fpu-internal.h>
58#include <asm/mce.h>
59#include <asm/fixmap.h>
60#include <asm/mach_traps.h>
61#include <asm/alternative.h>
62
63#ifdef CONFIG_X86_64
64#include <asm/x86_init.h>
65#include <asm/pgalloc.h>
66#include <asm/proto.h>
67
68/* No need to be aligned, but done to keep all IDTs defined the same way. */
69gate_desc debug_idt_table[NR_VECTORS] __page_aligned_bss;
70#else
71#include <asm/processor-flags.h>
72#include <asm/setup.h>
73
74asmlinkage int system_call(void);
75#endif
76
77/* Must be page-aligned because the real IDT is used in a fixmap. */
78gate_desc idt_table[NR_VECTORS] __page_aligned_bss;
79
80DECLARE_BITMAP(used_vectors, NR_VECTORS);
81EXPORT_SYMBOL_GPL(used_vectors);
82
83static inline void conditional_sti(struct pt_regs *regs)
84{
85 if (regs->flags & X86_EFLAGS_IF)
86 local_irq_enable();
87}
88
89static inline void preempt_conditional_sti(struct pt_regs *regs)
90{
91 preempt_count_inc();
92 if (regs->flags & X86_EFLAGS_IF)
93 local_irq_enable();
94}
95
96static inline void conditional_cli(struct pt_regs *regs)
97{
98 if (regs->flags & X86_EFLAGS_IF)
99 local_irq_disable();
100}
101
102static inline void preempt_conditional_cli(struct pt_regs *regs)
103{
104 if (regs->flags & X86_EFLAGS_IF)
105 local_irq_disable();
106 preempt_count_dec();
107}
108
109static int __kprobes
110do_trap_no_signal(struct task_struct *tsk, int trapnr, char *str,
111 struct pt_regs *regs, long error_code)
112{
113#ifdef CONFIG_X86_32
114 if (regs->flags & X86_VM_MASK) {
115 /*
116 * Traps 0, 1, 3, 4, and 5 should be forwarded to vm86.
117 * On nmi (interrupt 2), do_trap should not be called.
118 */
119 if (trapnr < X86_TRAP_UD) {
120 if (!handle_vm86_trap((struct kernel_vm86_regs *) regs,
121 error_code, trapnr))
122 return 0;
123 }
124 return -1;
125 }
126#endif
127 if (!user_mode(regs)) {
128 if (!fixup_exception(regs)) {
129 tsk->thread.error_code = error_code;
130 tsk->thread.trap_nr = trapnr;
131 die(str, regs, error_code);
132 }
133 return 0;
134 }
135
136 return -1;
137}
138
139static void __kprobes
140do_trap(int trapnr, int signr, char *str, struct pt_regs *regs,
141 long error_code, siginfo_t *info)
142{
143 struct task_struct *tsk = current;
144
145
146 if (!do_trap_no_signal(tsk, trapnr, str, regs, error_code))
147 return;
148 /*
149 * We want error_code and trap_nr set for userspace faults and
150 * kernelspace faults which result in die(), but not
151 * kernelspace faults which are fixed up. die() gives the
152 * process no chance to handle the signal and notice the
153 * kernel fault information, so that won't result in polluting
154 * the information about previously queued, but not yet
155 * delivered, faults. See also do_general_protection below.
156 */
157 tsk->thread.error_code = error_code;
158 tsk->thread.trap_nr = trapnr;
159
160#ifdef CONFIG_X86_64
161 if (show_unhandled_signals && unhandled_signal(tsk, signr) &&
162 printk_ratelimit()) {
163 pr_info("%s[%d] trap %s ip:%lx sp:%lx error:%lx",
164 tsk->comm, tsk->pid, str,
165 regs->ip, regs->sp, error_code);
166 print_vma_addr(" in ", regs->ip);
167 pr_cont("\n");
168 }
169#endif
170
171 if (info)
172 force_sig_info(signr, info, tsk);
173 else
174 force_sig(signr, tsk);
175}
176
177#define DO_ERROR(trapnr, signr, str, name) \
178dotraplinkage void do_##name(struct pt_regs *regs, long error_code) \
179{ \
180 enum ctx_state prev_state; \
181 \
182 prev_state = exception_enter(); \
183 if (notify_die(DIE_TRAP, str, regs, error_code, \
184 trapnr, signr) == NOTIFY_STOP) { \
185 exception_exit(prev_state); \
186 return; \
187 } \
188 conditional_sti(regs); \
189 do_trap(trapnr, signr, str, regs, error_code, NULL); \
190 exception_exit(prev_state); \
191}
192
193#define DO_ERROR_INFO(trapnr, signr, str, name, sicode, siaddr) \
194dotraplinkage void do_##name(struct pt_regs *regs, long error_code) \
195{ \
196 siginfo_t info; \
197 enum ctx_state prev_state; \
198 \
199 info.si_signo = signr; \
200 info.si_errno = 0; \
201 info.si_code = sicode; \
202 info.si_addr = (void __user *)siaddr; \
203 prev_state = exception_enter(); \
204 if (notify_die(DIE_TRAP, str, regs, error_code, \
205 trapnr, signr) == NOTIFY_STOP) { \
206 exception_exit(prev_state); \
207 return; \
208 } \
209 conditional_sti(regs); \
210 do_trap(trapnr, signr, str, regs, error_code, &info); \
211 exception_exit(prev_state); \
212}
213
214DO_ERROR_INFO(X86_TRAP_DE, SIGFPE, "divide error", divide_error, FPE_INTDIV, regs->ip )
215DO_ERROR (X86_TRAP_OF, SIGSEGV, "overflow", overflow )
216DO_ERROR (X86_TRAP_BR, SIGSEGV, "bounds", bounds )
217DO_ERROR_INFO(X86_TRAP_UD, SIGILL, "invalid opcode", invalid_op, ILL_ILLOPN, regs->ip )
218DO_ERROR (X86_TRAP_OLD_MF, SIGFPE, "coprocessor segment overrun", coprocessor_segment_overrun )
219DO_ERROR (X86_TRAP_TS, SIGSEGV, "invalid TSS", invalid_TSS )
220DO_ERROR (X86_TRAP_NP, SIGBUS, "segment not present", segment_not_present )
221#ifdef CONFIG_X86_32
222DO_ERROR (X86_TRAP_SS, SIGBUS, "stack segment", stack_segment )
223#endif
224DO_ERROR_INFO(X86_TRAP_AC, SIGBUS, "alignment check", alignment_check, BUS_ADRALN, 0 )
225
226#ifdef CONFIG_X86_64
227/* Runs on IST stack */
228dotraplinkage void do_stack_segment(struct pt_regs *regs, long error_code)
229{
230 enum ctx_state prev_state;
231
232 prev_state = exception_enter();
233 if (notify_die(DIE_TRAP, "stack segment", regs, error_code,
234 X86_TRAP_SS, SIGBUS) != NOTIFY_STOP) {
235 preempt_conditional_sti(regs);
236 do_trap(X86_TRAP_SS, SIGBUS, "stack segment", regs, error_code, NULL);
237 preempt_conditional_cli(regs);
238 }
239 exception_exit(prev_state);
240}
241
242dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code)
243{
244 static const char str[] = "double fault";
245 struct task_struct *tsk = current;
246
247 exception_enter();
248 /* Return not checked because double check cannot be ignored */
249 notify_die(DIE_TRAP, str, regs, error_code, X86_TRAP_DF, SIGSEGV);
250
251 tsk->thread.error_code = error_code;
252 tsk->thread.trap_nr = X86_TRAP_DF;
253
254#ifdef CONFIG_DOUBLEFAULT
255 df_debug(regs, error_code);
256#endif
257 /*
258 * This is always a kernel trap and never fixable (and thus must
259 * never return).
260 */
261 for (;;)
262 die(str, regs, error_code);
263}
264#endif
265
266dotraplinkage void __kprobes
267do_general_protection(struct pt_regs *regs, long error_code)
268{
269 struct task_struct *tsk;
270 enum ctx_state prev_state;
271
272 prev_state = exception_enter();
273 conditional_sti(regs);
274
275#ifdef CONFIG_X86_32
276 if (regs->flags & X86_VM_MASK) {
277 local_irq_enable();
278 handle_vm86_fault((struct kernel_vm86_regs *) regs, error_code);
279 goto exit;
280 }
281#endif
282
283 tsk = current;
284 if (!user_mode(regs)) {
285 if (fixup_exception(regs))
286 goto exit;
287
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);
293 goto exit;
294 }
295
296 tsk->thread.error_code = error_code;
297 tsk->thread.trap_nr = X86_TRAP_GP;
298
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);
305 pr_cont("\n");
306 }
307
308 force_sig(SIGSEGV, tsk);
309exit:
310 exception_exit(prev_state);
311}
312
313/* May run on IST stack. */
314dotraplinkage void __kprobes notrace do_int3(struct pt_regs *regs, long error_code)
315{
316 enum ctx_state prev_state;
317
318#ifdef CONFIG_DYNAMIC_FTRACE
319 /*
320 * ftrace must be first, everything else may cause a recursive crash.
321 * See note by declaration of modifying_ftrace_code in ftrace.c
322 */
323 if (unlikely(atomic_read(&modifying_ftrace_code)) &&
324 ftrace_int3_handler(regs))
325 return;
326#endif
327 if (poke_int3_handler(regs))
328 return;
329
330 prev_state = exception_enter();
331#ifdef CONFIG_KGDB_LOW_LEVEL_TRAP
332 if (kgdb_ll_trap(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP,
333 SIGTRAP) == NOTIFY_STOP)
334 goto exit;
335#endif /* CONFIG_KGDB_LOW_LEVEL_TRAP */
336
337 if (notify_die(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP,
338 SIGTRAP) == NOTIFY_STOP)
339 goto exit;
340
341 /*
342 * Let others (NMI) know that the debug stack is in use
343 * as we may switch to the interrupt stack.
344 */
345 debug_stack_usage_inc();
346 preempt_conditional_sti(regs);
347 do_trap(X86_TRAP_BP, SIGTRAP, "int3", regs, error_code, NULL);
348 preempt_conditional_cli(regs);
349 debug_stack_usage_dec();
350exit:
351 exception_exit(prev_state);
352}
353
354#ifdef CONFIG_X86_64
355/*
356 * Help handler running on IST stack to switch back to user stack
357 * for scheduling or signal handling. The actual stack switch is done in
358 * entry.S
359 */
360asmlinkage __visible __kprobes struct pt_regs *sync_regs(struct pt_regs *eregs)
361{
362 struct pt_regs *regs = eregs;
363 /* Did already sync */
364 if (eregs == (struct pt_regs *)eregs->sp)
365 ;
366 /* Exception from user space */
367 else if (user_mode(eregs))
368 regs = task_pt_regs(current);
369 /*
370 * Exception from kernel and interrupts are enabled. Move to
371 * kernel process stack.
372 */
373 else if (eregs->flags & X86_EFLAGS_IF)
374 regs = (struct pt_regs *)(eregs->sp -= sizeof(struct pt_regs));
375 if (eregs != regs)
376 *regs = *eregs;
377 return regs;
378}
379#endif
380
381/*
382 * Our handling of the processor debug registers is non-trivial.
383 * We do not clear them on entry and exit from the kernel. Therefore
384 * it is possible to get a watchpoint trap here from inside the kernel.
385 * However, the code in ./ptrace.c has ensured that the user can
386 * only set watchpoints on userspace addresses. Therefore the in-kernel
387 * watchpoint trap can only occur in code which is reading/writing
388 * from user space. Such code must not hold kernel locks (since it
389 * can equally take a page fault), therefore it is safe to call
390 * force_sig_info even though that claims and releases locks.
391 *
392 * Code in ./signal.c ensures that the debug control register
393 * is restored before we deliver any signal, and therefore that
394 * user code runs with the correct debug control register even though
395 * we clear it here.
396 *
397 * Being careful here means that we don't have to be as careful in a
398 * lot of more complicated places (task switching can be a bit lazy
399 * about restoring all the debug state, and ptrace doesn't have to
400 * find every occurrence of the TF bit that could be saved away even
401 * by user code)
402 *
403 * May run on IST stack.
404 */
405dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code)
406{
407 struct task_struct *tsk = current;
408 enum ctx_state prev_state;
409 int user_icebp = 0;
410 unsigned long dr6;
411 int si_code;
412
413 prev_state = exception_enter();
414
415 get_debugreg(dr6, 6);
416
417 /* Filter out all the reserved bits which are preset to 1 */
418 dr6 &= ~DR6_RESERVED;
419
420 /*
421 * If dr6 has no reason to give us about the origin of this trap,
422 * then it's very likely the result of an icebp/int01 trap.
423 * User wants a sigtrap for that.
424 */
425 if (!dr6 && user_mode(regs))
426 user_icebp = 1;
427
428 /* Catch kmemcheck conditions first of all! */
429 if ((dr6 & DR_STEP) && kmemcheck_trap(regs))
430 goto exit;
431
432 /* DR6 may or may not be cleared by the CPU */
433 set_debugreg(0, 6);
434
435 /*
436 * The processor cleared BTF, so don't mark that we need it set.
437 */
438 clear_tsk_thread_flag(tsk, TIF_BLOCKSTEP);
439
440 /* Store the virtualized DR6 value */
441 tsk->thread.debugreg6 = dr6;
442
443 if (notify_die(DIE_DEBUG, "debug", regs, (long)&dr6, error_code,
444 SIGTRAP) == NOTIFY_STOP)
445 goto exit;
446
447 /*
448 * Let others (NMI) know that the debug stack is in use
449 * as we may switch to the interrupt stack.
450 */
451 debug_stack_usage_inc();
452
453 /* It's safe to allow irq's after DR6 has been saved */
454 preempt_conditional_sti(regs);
455
456 if (regs->flags & X86_VM_MASK) {
457 handle_vm86_trap((struct kernel_vm86_regs *) regs, error_code,
458 X86_TRAP_DB);
459 preempt_conditional_cli(regs);
460 debug_stack_usage_dec();
461 goto exit;
462 }
463
464 /*
465 * Single-stepping through system calls: ignore any exceptions in
466 * kernel space, but re-enable TF when returning to user mode.
467 *
468 * We already checked v86 mode above, so we can check for kernel mode
469 * by just checking the CPL of CS.
470 */
471 if ((dr6 & DR_STEP) && !user_mode(regs)) {
472 tsk->thread.debugreg6 &= ~DR_STEP;
473 set_tsk_thread_flag(tsk, TIF_SINGLESTEP);
474 regs->flags &= ~X86_EFLAGS_TF;
475 }
476 si_code = get_si_code(tsk->thread.debugreg6);
477 if (tsk->thread.debugreg6 & (DR_STEP | DR_TRAP_BITS) || user_icebp)
478 send_sigtrap(tsk, regs, error_code, si_code);
479 preempt_conditional_cli(regs);
480 debug_stack_usage_dec();
481
482exit:
483 exception_exit(prev_state);
484}
485
486/*
487 * Note that we play around with the 'TS' bit in an attempt to get
488 * the correct behaviour even in the presence of the asynchronous
489 * IRQ13 behaviour
490 */
491void math_error(struct pt_regs *regs, int error_code, int trapnr)
492{
493 struct task_struct *task = current;
494 siginfo_t info;
495 unsigned short err;
496 char *str = (trapnr == X86_TRAP_MF) ? "fpu exception" :
497 "simd exception";
498
499 if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, SIGFPE) == NOTIFY_STOP)
500 return;
501 conditional_sti(regs);
502
503 if (!user_mode_vm(regs))
504 {
505 if (!fixup_exception(regs)) {
506 task->thread.error_code = error_code;
507 task->thread.trap_nr = trapnr;
508 die(str, regs, error_code);
509 }
510 return;
511 }
512
513 /*
514 * Save the info for the exception handler and clear the error.
515 */
516 save_init_fpu(task);
517 task->thread.trap_nr = trapnr;
518 task->thread.error_code = error_code;
519 info.si_signo = SIGFPE;
520 info.si_errno = 0;
521 info.si_addr = (void __user *)regs->ip;
522 if (trapnr == X86_TRAP_MF) {
523 unsigned short cwd, swd;
524 /*
525 * (~cwd & swd) will mask out exceptions that are not set to unmasked
526 * status. 0x3f is the exception bits in these regs, 0x200 is the
527 * C1 reg you need in case of a stack fault, 0x040 is the stack
528 * fault bit. We should only be taking one exception at a time,
529 * so if this combination doesn't produce any single exception,
530 * then we have a bad program that isn't synchronizing its FPU usage
531 * and it will suffer the consequences since we won't be able to
532 * fully reproduce the context of the exception
533 */
534 cwd = get_fpu_cwd(task);
535 swd = get_fpu_swd(task);
536
537 err = swd & ~cwd;
538 } else {
539 /*
540 * The SIMD FPU exceptions are handled a little differently, as there
541 * is only a single status/control register. Thus, to determine which
542 * unmasked exception was caught we must mask the exception mask bits
543 * at 0x1f80, and then use these to mask the exception bits at 0x3f.
544 */
545 unsigned short mxcsr = get_fpu_mxcsr(task);
546 err = ~(mxcsr >> 7) & mxcsr;
547 }
548
549 if (err & 0x001) { /* Invalid op */
550 /*
551 * swd & 0x240 == 0x040: Stack Underflow
552 * swd & 0x240 == 0x240: Stack Overflow
553 * User must clear the SF bit (0x40) if set
554 */
555 info.si_code = FPE_FLTINV;
556 } else if (err & 0x004) { /* Divide by Zero */
557 info.si_code = FPE_FLTDIV;
558 } else if (err & 0x008) { /* Overflow */
559 info.si_code = FPE_FLTOVF;
560 } else if (err & 0x012) { /* Denormal, Underflow */
561 info.si_code = FPE_FLTUND;
562 } else if (err & 0x020) { /* Precision */
563 info.si_code = FPE_FLTRES;
564 } else {
565 /*
566 * If we're using IRQ 13, or supposedly even some trap
567 * X86_TRAP_MF implementations, it's possible
568 * we get a spurious trap, which is not an error.
569 */
570 return;
571 }
572 force_sig_info(SIGFPE, &info, task);
573}
574
575dotraplinkage void do_coprocessor_error(struct pt_regs *regs, long error_code)
576{
577 enum ctx_state prev_state;
578
579 prev_state = exception_enter();
580 math_error(regs, error_code, X86_TRAP_MF);
581 exception_exit(prev_state);
582}
583
584dotraplinkage void
585do_simd_coprocessor_error(struct pt_regs *regs, long error_code)
586{
587 enum ctx_state prev_state;
588
589 prev_state = exception_enter();
590 math_error(regs, error_code, X86_TRAP_XF);
591 exception_exit(prev_state);
592}
593
594dotraplinkage void
595do_spurious_interrupt_bug(struct pt_regs *regs, long error_code)
596{
597 conditional_sti(regs);
598#if 0
599 /* No need to warn about this any longer. */
600 pr_info("Ignoring P6 Local APIC Spurious Interrupt Bug...\n");
601#endif
602}
603
604asmlinkage __visible void __attribute__((weak)) smp_thermal_interrupt(void)
605{
606}
607
608asmlinkage __visible void __attribute__((weak)) smp_threshold_interrupt(void)
609{
610}
611
612/*
613 * 'math_state_restore()' saves the current math information in the
614 * old math state array, and gets the new ones from the current task
615 *
616 * Careful.. There are problems with IBM-designed IRQ13 behaviour.
617 * Don't touch unless you *really* know how it works.
618 *
619 * Must be called with kernel preemption disabled (eg with local
620 * local interrupts as in the case of do_device_not_available).
621 */
622void math_state_restore(void)
623{
624 struct task_struct *tsk = current;
625
626 if (!tsk_used_math(tsk)) {
627 local_irq_enable();
628 /*
629 * does a slab alloc which can sleep
630 */
631 if (init_fpu(tsk)) {
632 /*
633 * ran out of memory!
634 */
635 do_group_exit(SIGKILL);
636 return;
637 }
638 local_irq_disable();
639 }
640
641 __thread_fpu_begin(tsk);
642
643 /*
644 * Paranoid restore. send a SIGSEGV if we fail to restore the state.
645 */
646 if (unlikely(restore_fpu_checking(tsk))) {
647 drop_init_fpu(tsk);
648 force_sig(SIGSEGV, tsk);
649 return;
650 }
651
652 tsk->thread.fpu_counter++;
653}
654EXPORT_SYMBOL_GPL(math_state_restore);
655
656dotraplinkage void __kprobes
657do_device_not_available(struct pt_regs *regs, long error_code)
658{
659 enum ctx_state prev_state;
660
661 prev_state = exception_enter();
662 BUG_ON(use_eager_fpu());
663
664#ifdef CONFIG_MATH_EMULATION
665 if (read_cr0() & X86_CR0_EM) {
666 struct math_emu_info info = { };
667
668 conditional_sti(regs);
669
670 info.regs = regs;
671 math_emulate(&info);
672 exception_exit(prev_state);
673 return;
674 }
675#endif
676 math_state_restore(); /* interrupts still off */
677#ifdef CONFIG_X86_32
678 conditional_sti(regs);
679#endif
680 exception_exit(prev_state);
681}
682
683#ifdef CONFIG_X86_32
684dotraplinkage void do_iret_error(struct pt_regs *regs, long error_code)
685{
686 siginfo_t info;
687 enum ctx_state prev_state;
688
689 prev_state = exception_enter();
690 local_irq_enable();
691
692 info.si_signo = SIGILL;
693 info.si_errno = 0;
694 info.si_code = ILL_BADSTK;
695 info.si_addr = NULL;
696 if (notify_die(DIE_TRAP, "iret exception", regs, error_code,
697 X86_TRAP_IRET, SIGILL) != NOTIFY_STOP) {
698 do_trap(X86_TRAP_IRET, SIGILL, "iret exception", regs, error_code,
699 &info);
700 }
701 exception_exit(prev_state);
702}
703#endif
704
705/* Set of traps needed for early debugging. */
706void __init early_trap_init(void)
707{
708 set_intr_gate_ist(X86_TRAP_DB, &debug, DEBUG_STACK);
709 /* int3 can be called from all */
710 set_system_intr_gate_ist(X86_TRAP_BP, &int3, DEBUG_STACK);
711#ifdef CONFIG_X86_32
712 set_intr_gate(X86_TRAP_PF, page_fault);
713#endif
714 load_idt(&idt_descr);
715}
716
717void __init early_trap_pf_init(void)
718{
719#ifdef CONFIG_X86_64
720 set_intr_gate(X86_TRAP_PF, page_fault);
721#endif
722}
723
724void __init trap_init(void)
725{
726 int i;
727
728#ifdef CONFIG_EISA
729 void __iomem *p = early_ioremap(0x0FFFD9, 4);
730
731 if (readl(p) == 'E' + ('I'<<8) + ('S'<<16) + ('A'<<24))
732 EISA_bus = 1;
733 early_iounmap(p, 4);
734#endif
735
736 set_intr_gate(X86_TRAP_DE, divide_error);
737 set_intr_gate_ist(X86_TRAP_NMI, &nmi, NMI_STACK);
738 /* int4 can be called from all */
739 set_system_intr_gate(X86_TRAP_OF, &overflow);
740 set_intr_gate(X86_TRAP_BR, bounds);
741 set_intr_gate(X86_TRAP_UD, invalid_op);
742 set_intr_gate(X86_TRAP_NM, device_not_available);
743#ifdef CONFIG_X86_32
744 set_task_gate(X86_TRAP_DF, GDT_ENTRY_DOUBLEFAULT_TSS);
745#else
746 set_intr_gate_ist(X86_TRAP_DF, &double_fault, DOUBLEFAULT_STACK);
747#endif
748 set_intr_gate(X86_TRAP_OLD_MF, coprocessor_segment_overrun);
749 set_intr_gate(X86_TRAP_TS, invalid_TSS);
750 set_intr_gate(X86_TRAP_NP, segment_not_present);
751 set_intr_gate_ist(X86_TRAP_SS, &stack_segment, STACKFAULT_STACK);
752 set_intr_gate(X86_TRAP_GP, general_protection);
753 set_intr_gate(X86_TRAP_SPURIOUS, spurious_interrupt_bug);
754 set_intr_gate(X86_TRAP_MF, coprocessor_error);
755 set_intr_gate(X86_TRAP_AC, alignment_check);
756#ifdef CONFIG_X86_MCE
757 set_intr_gate_ist(X86_TRAP_MC, &machine_check, MCE_STACK);
758#endif
759 set_intr_gate(X86_TRAP_XF, simd_coprocessor_error);
760
761 /* Reserve all the builtin and the syscall vector: */
762 for (i = 0; i < FIRST_EXTERNAL_VECTOR; i++)
763 set_bit(i, used_vectors);
764
765#ifdef CONFIG_IA32_EMULATION
766 set_system_intr_gate(IA32_SYSCALL_VECTOR, ia32_syscall);
767 set_bit(IA32_SYSCALL_VECTOR, used_vectors);
768#endif
769
770#ifdef CONFIG_X86_32
771 set_system_trap_gate(SYSCALL_VECTOR, &system_call);
772 set_bit(SYSCALL_VECTOR, used_vectors);
773#endif
774
775 /*
776 * Set the IDT descriptor to a fixed read-only location, so that the
777 * "sidt" instruction will not leak the location of the kernel, and
778 * to defend the IDT against arbitrary memory write vulnerabilities.
779 * It will be reloaded in cpu_init() */
780 __set_fixmap(FIX_RO_IDT, __pa_symbol(idt_table), PAGE_KERNEL_RO);
781 idt_descr.address = fix_to_virt(FIX_RO_IDT);
782
783 /*
784 * Should be a barrier for any external CPU state:
785 */
786 cpu_init();
787
788 x86_init.irqs.trap_init();
789
790#ifdef CONFIG_X86_64
791 memcpy(&debug_idt_table, &idt_table, IDT_ENTRIES * 16);
792 set_nmi_gate(X86_TRAP_DB, &debug);
793 set_nmi_gate(X86_TRAP_BP, &int3);
794#endif
795}