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SubjectRe: [RFC PATCH 5/6] uprobes: add bp_vaddr argument to consumer handler
On Sun, Dec 23, 2012 at 04:49:10PM +0100, Oleg Nesterov wrote:
> On 12/22, Oleg Nesterov wrote:
> >
> > Forgot to ask...
> >
> > On 12/22, Oleg Nesterov wrote:
> > >
> > > On 12/21, Anton Arapov wrote:
> > > >
> > > > struct uprobe_consumer {
> > > > - int (*handler)(struct uprobe_consumer *self, struct pt_regs *regs);
> > > > + int (*handler)(struct uprobe_consumer *self, unsigned long bp_vaddr, struct pt_regs *regs);
> > >
> > > It seems that we can do better...
> > >
> > > Just change regs->ip before calling ->handler().
> >
> > Josh, Frank, will it work for you?
>
> Wait, probably I was confused by this patch and 4/6...
>
> To simplify, lets ignore the normal uprobes. Yes I still think that it
> would be better to set "regs->ip = orig_return_vaddr" before calling
> ->handler() and not pass it as an argument.
>
> But, probably uprobe_consumer also needs to know bp_vaddr? IOW, the
> address of the function which we are going to return from? In this case,
> yes, we also need another argument. And prepare_uretprobe/etc should
> be changed to record bp_vaddr passed from handle_swbp(). And
> uretprobe_run_handlers() should pass this bp_vaddr, not orig_return_vaddr.
>
> Or I am confused.
>
> Anton?

Oleg, you are absolutely right and change the ip before calling the
->handle is much better then what I 'invented'.

I'm working on v2 to address this and other issues, will post it soon.

Anton.


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