Re: [RFC PATCH] kernel/kallsyms.c: only show legal kernel symbol

From: Rusty Russell
Date: Fri Oct 25 2013 - 19:30:33 EST


Ming Lei <tom.leiming@xxxxxxxxx> writes:
> On Fri, Oct 25, 2013 at 1:50 PM, Rusty Russell <rusty@xxxxxxxxxxxxxxx> wrote:
>> Ming Lei <tom.leiming@xxxxxxxxx> writes:
>>> On Fri, Oct 25, 2013 at 7:08 AM, Rusty Russell <rusty@xxxxxxxxxxxxxxx> wrote:
>>>>
>>>> Sorry, I was imprecise. I was referring to the kernel's kallsyms
>>>> tables produced by scripts/kallsyms.c. This patch left them in the
>>>> the kallsyms tables and filtered them out from /proc/kallsyms.
>>>
>>> Yes, but it isn't easy to do it by script/kallsyms.c , and IMO, it should
>>> be correct to hide them for user space but keep them in kallsyms table.
>>
>> So they'll appear in backtraces? And turn up randomly for other symbol
>> dereferences?
>>
>> I don't think you really want this!
>
> Basically these symbols are only used to generate code, and in
> kernel mode, CPU won't run into the corresponding addresses
> because the generate code is copied to other address during booting,
> so I understand they won't appear in backtraces.

An oops occurs when something went *wrong*. We look up all kinds of
stuff. Are you so sure that *none* of the callers will ever see these
strange symbols and produce a confusing result?

Cheers,
Rusty.



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