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Diffstat (limited to 'arch/x86/kernel/traps.c')
-rw-r--r--arch/x86/kernel/traps.c73
1 files changed, 26 insertions, 47 deletions
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 7e37dcee0cc3..33399176512a 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -529,77 +529,56 @@ asmlinkage __kprobes struct pt_regs *sync_regs(struct pt_regs *eregs)
529dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code) 529dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code)
530{ 530{
531 struct task_struct *tsk = current; 531 struct task_struct *tsk = current;
532 unsigned long condition; 532 unsigned long dr6;
533 int si_code; 533 int si_code;
534 534
535 get_debugreg(condition, 6); 535 get_debugreg(dr6, 6);
536 536
537 /* Catch kmemcheck conditions first of all! */ 537 /* Catch kmemcheck conditions first of all! */
538 if (condition & DR_STEP && kmemcheck_trap(regs)) 538 if ((dr6 & DR_STEP) && kmemcheck_trap(regs))
539 return; 539 return;
540 540
541 /* DR6 may or may not be cleared by the CPU */
542 set_debugreg(0, 6);
541 /* 543 /*
542 * The processor cleared BTF, so don't mark that we need it set. 544 * The processor cleared BTF, so don't mark that we need it set.
543 */ 545 */
544 clear_tsk_thread_flag(tsk, TIF_DEBUGCTLMSR); 546 clear_tsk_thread_flag(tsk, TIF_DEBUGCTLMSR);
545 tsk->thread.debugctlmsr = 0; 547 tsk->thread.debugctlmsr = 0;
546 548
547 if (notify_die(DIE_DEBUG, "debug", regs, condition, error_code, 549 /* Store the virtualized DR6 value */
548 SIGTRAP) == NOTIFY_STOP) 550 tsk->thread.debugreg6 = dr6;
551
552 if (notify_die(DIE_DEBUG, "debug", regs, PTR_ERR(&dr6), error_code,
553 SIGTRAP) == NOTIFY_STOP)
549 return; 554 return;
550 555
551 /* It's safe to allow irq's after DR6 has been saved */ 556 /* It's safe to allow irq's after DR6 has been saved */
552 preempt_conditional_sti(regs); 557 preempt_conditional_sti(regs);
553 558
554 /* Mask out spurious debug traps due to lazy DR7 setting */ 559 if (regs->flags & X86_VM_MASK) {
555 if (condition & (DR_TRAP0|DR_TRAP1|DR_TRAP2|DR_TRAP3)) { 560 handle_vm86_trap((struct kernel_vm86_regs *) regs,
556 if (!tsk->thread.debugreg7) 561 error_code, 1);
557 goto clear_dr7; 562 return;
558 } 563 }
559 564
560#ifdef CONFIG_X86_32
561 if (regs->flags & X86_VM_MASK)
562 goto debug_vm86;
563#endif
564
565 /* Save debug status register where ptrace can see it */
566 tsk->thread.debugreg6 = condition;
567
568 /* 565 /*
569 * Single-stepping through TF: make sure we ignore any events in 566 * Single-stepping through system calls: ignore any exceptions in
570 * kernel space (but re-enable TF when returning to user mode). 567 * kernel space, but re-enable TF when returning to user mode.
568 *
569 * We already checked v86 mode above, so we can check for kernel mode
570 * by just checking the CPL of CS.
571 */ 571 */
572 if (condition & DR_STEP) { 572 if ((dr6 & DR_STEP) && !user_mode(regs)) {
573 if (!user_mode(regs)) 573 tsk->thread.debugreg6 &= ~DR_STEP;
574 goto clear_TF_reenable; 574 set_tsk_thread_flag(tsk, TIF_SINGLESTEP);
575 regs->flags &= ~X86_EFLAGS_TF;
575 } 576 }
576 577 si_code = get_si_code(tsk->thread.debugreg6);
577 si_code = get_si_code(condition); 578 if (tsk->thread.debugreg6 & (DR_STEP | DR_TRAP_BITS))
578 /* Ok, finally something we can handle */ 579 send_sigtrap(tsk, regs, error_code, si_code);
579 send_sigtrap(tsk, regs, error_code, si_code);
580
581 /*
582 * Disable additional traps. They'll be re-enabled when
583 * the signal is delivered.
584 */
585clear_dr7:
586 set_debugreg(0, 7);
587 preempt_conditional_cli(regs); 580 preempt_conditional_cli(regs);
588 return;
589 581
590#ifdef CONFIG_X86_32
591debug_vm86:
592 /* reenable preemption: handle_vm86_trap() might sleep */
593 dec_preempt_count();
594 handle_vm86_trap((struct kernel_vm86_regs *) regs, error_code, 1);
595 conditional_cli(regs);
596 return;
597#endif
598
599clear_TF_reenable:
600 set_tsk_thread_flag(tsk, TIF_SINGLESTEP);
601 regs->flags &= ~X86_EFLAGS_TF;
602 preempt_conditional_cli(regs);
603 return; 582 return;
604} 583}
605 584