Messages in this thread | | | Date | Fri, 21 Oct 2011 18:22:19 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH 12/X] uprobes: x86: introduce abort_xol() |
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On 10/21, Srikar Dronamraju wrote: > > > If it is not clear, abort_xol() is needed when we should > > re-execute the original insn (replaced with int3), see the > > next patch. > > We should be removing the breakpoint in abort_xol().
Why? See also below.
> Otherwise if we just set the instruction pointer to int3 and signal a > sigill, then the user may be confused why a breakpoint is generating > SIGILL.
Which user?
gdb? Of course it can be confused. But it can be confused in any case.
> > +void abort_xol(struct pt_regs *regs) > > +{ > > + // !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! > > + // !!! Dear Srikar and Ananth, please implement me !!! > > + // !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! > > + struct uprobe_task *utask = current->utask; > > + regs->ip = utask->vaddr; > > nit: > Shouldnt we be setting the ip to the next instruction after this > instruction?
Not sure...
We should restart the same insn. Say, if the probed insn was "*(int*)0 = 0", it should be executed again after SIGSEGV. Unless the task was killed by this signal.
And in this case we should call uprobe_consumer()->handler() again, we shouldn't remove "int3".
> I have applied all your patches and ran tests, the tests are all > passing. > > I will fold them into my patches and send them out.
Great, thanks.
Oleg.
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