linux-kernel - Re: [GIT PULL] x86/kaslr for v3.14

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Message-ID: <CA+rthh93phituM24W8KrGygvKtUmByJUtOCS-sELj4QgLqS3cw@mail.gmail.com>
Date:	Wed, 29 Jan 2014 09:27:08 +0100
From:	Mathias Krause <minipli@...glemail.com>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	Richard Weinberger <richard@....at>,
	"H. Peter Anvin" <hpa@...ux.intel.com>,
	Kees Cook <keescook@...omium.org>,
	Cong Ding <dinggnu@...il.com>, Ingo Molnar <mingo@...e.hu>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Michael Davidson <md@...gle.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Wei Yongjun <yongjun_wei@...ndmicro.com.cn>
Subject: Re: [GIT PULL] x86/kaslr for v3.14

On 29 January 2014 09:11, Ingo Molnar <mingo@...nel.org> wrote:
>> But you can see that the symbol is perfectly fine:
>>
>>   (gdb) list *(schedule+0x45)
>
> Oh, cool. Thanks for that trick - this will save me quite some time in
> the future.
>
> So we can strip absolute addresses just fine from oopses - cool.
>
> I'd even argue to strip the hex on non-randomized kernels as long as
> there's kallsyms around, and only print hex if we don't have any
> symbols.

Please, don't do so! I do find the hex values in the backtrace *very*
useful as I'm using 'objdump -wdr vmlinux | less' quite often to
"browse around" in the kernel binary. Grepping for addresses from a
backtrace works quite nicely this way. Having to lookup symbols and do
base-16 arithmetics in the head (or a shell, for that matter) would
only slow down this process. So, please leave the hex values in place.
They do help a lot -- at least in the non-kASLR case.

Regards,
Mathias
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