Re: [PATCH 3/3] x86: WARN_ON breakpoints from .kprobes.text section

[Abhishek Sagar]

On 1/27/08, Masami Hiramatsu <mhiramat@xxxxxxxxxx> wrote:
> Sorry, I can not understand what issue these patches can solve.
> The breakpoint which is inserted by external debugger will be checked by
> kprobe_handler() and be passed to other exception_notify_handlers.
> In that case, we don't need to warn it.
> I think current code is enough simple.

kprobe_handler has a blanket check for all non-kprobe breakpoints.
They're all left to the kernel to handle. This is fine. Although
external debuggers are free to plant breakpoints anywhere, they should
be discouraged from doing so inside .kprobes.text region. Placing them
there may lead to recursive page-fault/trap handling. It's a defensive
check. I hope I've been able to clarify.

> --
> Masami Hiramatsu
>
> Software Engineer
> Hitachi Computer Products (America) Inc.
> Software Solutions Division
>
> e-mail: mhiramat@xxxxxxxxxx

Thanks,
Abhishek Sagar
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