Re: [PATCH v5 3.1.0-rc4-tip 17/26] x86: arch specific hooks forpre/post singlestep handling.

[Srikar Dronamraju]

* Peter Zijlstra <peterz@xxxxxxxxxxxxx> [2011-09-26 16:23:53]:

> On Tue, 2011-09-20 at 17:33 +0530, Srikar Dronamraju wrote:
> > +fail:
> > +       pr_warn_once("uprobes: Failed to adjust return address after"
> > +               " single-stepping call instruction;"
> > +               " pid=%d, sp=%#lx\n", current->pid, sp);
> > +       return -EFAULT; 
> 
> So how can that happen? Single-Step while someone unmapped the stack?

We do a copy_to_user, copy_from_user just above this, Now if either of
them fail, we have no choice but to Bail out. What caused this EFault
may not be under Uprobes's Control.

-- 
Thanks and Regards
Srikar

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