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From: Vivek Goyal <vgoyal@redhat.com>
To: WANG Chao <chaowang@redhat.com>
Cc: kexec@lists.infradead.org, Simon Horman <horms@verge.net.au>,
	Dave Young <dyoung@redhat.com>
Subject: Re: [kexec-tools PATCH] x86, kaslr: add alternative way to locate kernel text mapping area
Date: Thu, 27 Mar 2014 17:57:17 -0400	[thread overview]
Message-ID: <20140327215717.GO13816@redhat.com> (raw)
In-Reply-To: <20140327102548.GA15941@dhcp-17-89.nay.redhat.com>

On Thu, Mar 27, 2014 at 06:25:48PM +0800, WANG Chao wrote:

[..]
> @@ -169,6 +200,31 @@ static int get_kernel_vaddr_and_size(struct kexec_info *UNUSED(info),
>  			}
>  		}
>  	}
> +
> +	/* Go through /proc/kcore again. This time we find the region
> +	 * where _stext symbol is located in */

Hi Chao,

How about doing it reverse. Using _stext seems to be the right thing to
do both for kaslr enabled as well as kaslr disabled kernel. Right now
assuming that kernel text mapping fall in a certain area is a hack
and will break if kernel addresses are shifted again for whatever reason.

So we can first look for kernel mapping using _stext. If /proc/kallsyms
is not present, then we can fall back using hardcoded address range
between X86_64__START_KERNEL_map and X86_64__START_KERNEL_map +
X86_64_KERNEL_TEXT_SIZE.

Thanks
Vivek

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  reply	other threads:[~2014-03-27 21:57 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-03-27 10:25 [kexec-tools PATCH] x86, kaslr: add alternative way to locate kernel text mapping area WANG Chao
2014-03-27 21:57 ` Vivek Goyal [this message]
2014-03-28  6:20   ` WANG Chao

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