Re: [PATCH 5/7] uprobes/x86: Gather "riprel" functions together

[Oleg Nesterov <oleg@redhat.com>]

On 04/02, Jim Keniston wrote:
>
> On Mon, 2014-03-31 at 21:44 +0200, Oleg Nesterov wrote:
> ...
> > +static void
> > +handle_riprel_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs, long *correction)
> > +{
> > +	if (auprobe->fixups & (UPROBE_FIX_RIP_AX | UPROBE_FIX_RIP_CX)) {
> > +		struct arch_uprobe_task *autask;
> > +
> > +		autask = &current->utask->autask;
> > +		if (auprobe->fixups & UPROBE_FIX_RIP_AX)
> > +			regs->ax = autask->saved_scratch_register;
> > +		else
> > +			regs->cx = autask->saved_scratch_register;
> > +
> > +		/*
> > +		 * The original instruction includes a displacement, and so
> > +		 * is 4 bytes longer than what we've just single-stepped.
> > +		 * Fall through to handle stuff like "jmpq *...(%rip)" and
> > +		 * "callq *...(%rip)".
> > +		 */
> > +		if (correction)
> > +			*correction += 4;
> > +	}
> > +}
>
> This is another case of a glitch in the code being moved.  Since this
> code was moved to its own function, the "Fall through" comment makes no
> sense.  Maybe
> 		 * Caller may need to apply other fixups to handle stuff
> 		 * like "jmpq *...(%rip)" and "callq *...(%rip)".

Thanks. updated the comment in v2.

Oleg.