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

[Oleg Nesterov]

On 10/10, Oleg Nesterov wrote:
>
> 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() ?

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.

Oleg.

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