Re: [PATCH v7 3.2-rc2 8/30] x86: analyze instruction and determinefixups.

[Srikar Dronamraju]

* Oleg Nesterov <oleg@xxxxxxxxxx> [2011-11-30 19:57:51]:

> On 11/18, Srikar Dronamraju wrote:
> >
> > +static void handle_riprel_insn(struct mm_struct *mm, struct uprobe *uprobe,
> > +							struct insn *insn)
> > +{
> > [...snip...]
> > +	if (insn->immediate.nbytes) {
> > +		cursor++;
> > +		memmove(cursor, cursor + insn->displacement.nbytes,
> > +						insn->immediate.nbytes);
> > +	}
> > +	return;
> > +}
> 
> Of course I don not understand this code. But it seems that it can
> rewrite uprobe->insn ?
> 

Yes, we do rewrite the instruction for the RIP relative instructions. 
But the first byte is still intact.

> If yes, don't we need to save the original insn for unregister_uprobe?

When we unregister, we just put back the least opcode size which
happens to be the first byte for x86.

-- 
Thanks and Regards
Srikar

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