Re: x86-64: int3 no longer causes SIGTRAP in 2.6.10

[Andi Kleen <ak@muc.de>]

> Yes its a bug, we turn trap 3 into interrupt gates to ensure that it is not preemtable.

Is the patch ok for you?

-Andi

> > Like this patch.
> > 
> > Index: linux/arch/x86_64/kernel/traps.c
> > ===================================================================
> > --- linux.orig/arch/x86_64/kernel/traps.c	2005-01-17 10:34:24.%N +0100
> > +++ linux/arch/x86_64/kernel/traps.c	2005-01-18 02:42:02.%N +0100
> > @@ -908,7 +908,7 @@
> >  	set_intr_gate(0,&divide_error);
> >  	set_intr_gate_ist(1,&debug,DEBUG_STACK);
> >  	set_intr_gate_ist(2,&nmi,NMI_STACK);
> > -	set_intr_gate(3,&int3);
> > +	set_system_gate(3,&int3);
> >  	set_system_gate(4,&overflow);	/* int4-5 can be called from all */
> >  	set_system_gate(5,&bounds);
> >  	set_intr_gate(6,&invalid_op);
> > Index: linux/arch/x86_64/kernel/kprobes.c
> > ===================================================================
> > --- linux.orig/arch/x86_64/kernel/kprobes.c	2005-01-04 12:12:39.%N +0100
> > +++ linux/arch/x86_64/kernel/kprobes.c	2005-01-18 02:46:05.%N +0100
> > @@ -297,6 +297,8 @@
> >  	struct die_args *args = (struct die_args *)data;
> >  	switch (val) {
> >  	case DIE_INT3:
> > +		if (args->regs->cs & 3)
> > +			return NOTIFY_DONE;
> >  		if (kprobe_handler(args->regs))
> >  			return NOTIFY_STOP;
> >  		break;
> > 
> >