Re: [PATCH v5 3.1.0-rc4-tip 26/26] uprobes: queue signals whilethread is singlestepping.

[Srikar Dronamraju]

> > HOWEVER! I simply do not know what should we do if the probed insn
> > is something like asm("1:; jmp 1b;"). IIUC, in this sstep_complete()
> > never returns true. The patch also adds the fatal_signal_pending()
> > check to make this task killlable, but the problem is: whatever we do,
> > I do not think it is correct to disable/delay the signals in this case.
> > With any approach.
> >
> > What do you think? Maybe we should simply disallow to probe such insns?
> 
> Or. Could you explain why we can't simply remove the
> "if (vaddr == current->utask->xol_vaddr)" check from sstep_complete() ?


Yes, we could remove the check and rely on just the DIE_DEBUG to say
that singlestep has occurred. This was mostly needed when we were not
handling signals on singlestep.

> In some sense, imho this looks more correct for "rep" or jmp/call self.
> The task will trap again on the same (original) address, and
> handler_chain() will be called to notify the consumers.
> 
> But. I am really, really ignorant in this area, I am almost sure this
> is not that simple.
> 

Thats being modest.

-- 
Thanks and Regards
Srikar
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