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From: rusty@rustcorp.com.au (Rusty Russell)
To: linux-arm-kernel@lists.infradead.org
Subject: [RFC PATCH] kernel/kallsyms.c: only show legal kernel symbol
Date: Fri, 25 Oct 2013 22:28:29 +1030	[thread overview]
Message-ID: <87sivp7eai.fsf@rustcorp.com.au> (raw)
In-Reply-To: <CACVXFVPXEUX9JQ2NZvL8=J34zbw2fn202QW2SQtpKjdQ+tv=vg@mail.gmail.com>

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

WARNING: multiple messages have this Message-ID (diff)
From: Rusty Russell <rusty@rustcorp.com.au>
To: Ming Lei <tom.leiming@gmail.com>
Cc: Russell King - ARM Linux <linux@arm.linux.org.uk>,
	Andrew Morton <akpm@linux-foundation.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Chen Gang <gang.chen@asianux.com>,
	linux-arm-kernel <linux-arm-kernel@lists.infradead.org>
Subject: Re: [RFC PATCH] kernel/kallsyms.c: only show legal kernel symbol
Date: Fri, 25 Oct 2013 22:28:29 +1030	[thread overview]
Message-ID: <87sivp7eai.fsf@rustcorp.com.au> (raw)
In-Reply-To: <CACVXFVPXEUX9JQ2NZvL8=J34zbw2fn202QW2SQtpKjdQ+tv=vg@mail.gmail.com>

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




  reply	other threads:[~2013-10-25 11:58 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-10-23  3:18 [RFC PATCH] kernel/kallsyms.c: only show legal kernel symbol Ming Lei
2013-10-23  3:18 ` Ming Lei
2013-10-24  1:21 ` Rusty Russell
2013-10-24  1:21   ` Rusty Russell
2013-10-24  5:42   ` Ming Lei
2013-10-24  5:42     ` Ming Lei
2013-10-24  8:45   ` Russell King - ARM Linux
2013-10-24  8:45     ` Russell King - ARM Linux
2013-10-24  9:10     ` Ming Lei
2013-10-24  9:10       ` Ming Lei
2013-10-24 23:08     ` Rusty Russell
2013-10-24 23:08       ` Rusty Russell
2013-10-25  1:29       ` Ming Lei
2013-10-25  1:29         ` Ming Lei
2013-10-25  5:50         ` Rusty Russell
2013-10-25  5:50           ` Rusty Russell
2013-10-25  7:01           ` Ming Lei
2013-10-25  7:01             ` Ming Lei
2013-10-25 11:58             ` Rusty Russell [this message]
2013-10-25 11:58               ` Rusty Russell
2013-10-26 12:31               ` Ming Lei
2013-10-26 12:31                 ` Ming Lei
2013-10-28  3:14                 ` Rusty Russell
2013-10-28  3:14                   ` Rusty Russell
2013-10-28  5:23                   ` Ming Lei
2013-10-28  5:23                     ` Ming Lei
2013-10-28  5:50                     ` Rusty Russell
2013-10-28  5:50                       ` Rusty Russell
2013-10-30 23:09                       ` Russell King - ARM Linux
2013-10-30 23:09                         ` Russell King - ARM Linux
2013-10-31  3:14                         ` Rusty Russell
2013-10-31  3:14                           ` Rusty Russell
2013-10-31  4:55                           ` Ming Lei
2013-10-31  4:55                             ` Ming Lei
2013-11-01  2:28                             ` Rusty Russell
2013-11-01  2:28                               ` Rusty Russell

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