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

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Message-ID: <87sivp7eai.fsf@rustcorp.com.au>
Date:	Fri, 25 Oct 2013 22:28:29 +1030
From:	Rusty Russell <rusty@...tcorp.com.au>
To:	Ming Lei <tom.leiming@...il.com>
Cc:	Russell King - ARM Linux <linux@....linux.org.uk>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Chen Gang <gang.chen@...anux.com>,
	linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [RFC PATCH] kernel/kallsyms.c: only show legal kernel symbol

Ming Lei <tom.leiming@...il.com> writes:
> On Fri, Oct 25, 2013 at 1:50 PM, Rusty Russell <rusty@...tcorp.com.au> wrote:
>> Ming Lei <tom.leiming@...il.com> writes:
>>> On Fri, Oct 25, 2013 at 7:08 AM, Rusty Russell <rusty@...tcorp.com.au> 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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