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Message-ID: <20080807131557.GB27783@redhat.com>
Date: Thu, 7 Aug 2008 09:15:57 -0400
From: Vivek Goyal <vgoyal@...hat.com>
To: Huang Ying <ying.huang@...el.com>
Cc: "Eric W. Biederman" <ebiederm@...ssion.com>,
Pavel Machek <pavel@....cz>, nigel@...el.suspend2.net,
"Rafael J. Wysocki" <rjw@...k.pl>,
Andrew Morton <akpm@...ux-foundation.org>, mingo@...e.hu,
Linus Torvalds <torvalds@...ux-foundation.org>,
linux-kernel@...r.kernel.org,
Kexec Mailing List <kexec@...ts.infradead.org>
Subject: Re: [PATCH 2/6] kexec jump: check code size in control page
On Thu, Aug 07, 2008 at 05:05:26PM +0800, Huang Ying wrote:
> Kexec/Kexec-jump requires code size in control page is less than
> PAGE_SIZE/2. This patch adds runtime checking for this.
>
> Signed-off-by: Huang Ying <ying.huang@...el.com>
>
> ---
> arch/x86/kernel/machine_kexec_32.c | 4 ++++
> arch/x86/kernel/relocate_kernel_32.S | 3 +++
> include/asm-x86/kexec.h | 1 +
> 3 files changed, 8 insertions(+)
>
> --- a/arch/x86/kernel/machine_kexec_32.c
> +++ b/arch/x86/kernel/machine_kexec_32.c
> @@ -92,6 +92,10 @@ int machine_kexec_prepare(struct kimage
> {
> if (nx_enabled)
> set_pages_x(image->control_code_page, 1);
> +
> + BUG_ON((unsigned long)kexec_control_page_code_end - \
> + (unsigned long)relocate_kernel >= PAGE_SIZE/2);
> +
Hi Huang,
Run time check is better than nothing but I think in this case it would
be better if we can catch it at compile time.
One of the methods will be to write a small program of your own and
put in script/ and at build time check for the size and flag error. May
be there are other better ways to do this.
Thanks
Vivek
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