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SubjectRe: [PATCH v5 3.1.0-rc4-tip 17/26] x86: arch specific hooks for pre/post singlestep handling.
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On Mon, 2011-09-26 at 22:04 +0530, Srikar Dronamraju wrote:
> * Peter Zijlstra <peterz@infradead.org> [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,

I saw that,

> Now if either of
> them fail, we have no choice but to Bail out.

Agreed,

> What caused this EFault may not be under Uprobes's Control.

I never said it was.. All I asked is what (outside of uprobe) was done
to cause this, and why is this particular error important enough to
warrant a warn.


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