From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from out02.mta.xmission.com ([166.70.13.232]) by bombadil.infradead.org with esmtp (Exim 4.68 #1 (Red Hat Linux)) id 1Jzdkr-0000N3-5N for kexec@lists.infradead.org; Fri, 23 May 2008 20:20:45 +0000 From: ebiederm@xmission.com (Eric W. Biederman) References: <4836AC3C.3090005@in.ibm.com> Date: Fri, 23 May 2008 13:14:42 -0700 In-Reply-To: <4836AC3C.3090005@in.ibm.com> (Sharyathi Nagesh's message of "Fri, 23 May 2008 17:06:28 +0530") Message-ID: MIME-Version: 1.0 Subject: Re: correction to compat_sys_kexec_load List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: kexec-bounces@lists.infradead.org Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: Sharyathi Nagesh Cc: akpm@osdl.org, mohd.omar@in.ibm.com, IndhuDurai@in.ibm.com, maneesh@in.ltcfwd.linux.ibm.com, Kexec Mailing List , fastboot@lists.osdl.org, linux-kernel@vger.kernel.org, mohan@in.ibm.com, sachinp@in.ibm.com Sharyathi Nagesh writes: > Hi > While testing with kexec tool, I observed some problems. When application > (kexec) is 32 bit and kernel is 64 bit I observed that loading crash kernel > works without any issues but unloading crash kernel fails. > -------------------------------------------------------- > running strace over 'kexec -u -p' > show the problem to be with sys_kexec_load() call > > sys_kexec_load(0, 0, 0, 0x1, 0) = -1 EINVAL (Invalid argument) > write(2, "kexec_load (0 segments) failed: "..., 49 > kexec_load (0 segments) failed: Invalid argument > ) = 4 Yes. This is a bug. Although not in the kernel implementation. > -------------------------------------------------------- > > This is patch to fix the problem, I think kernel code had a typo where in: > if((flags & KEXEC_ARCH_MASK) == KEXEC_ARCH) was used instead of > if((flags & KEXEC_ARCH_MASK) != KEXEC_ARCH) Nope. We do the latter check after we have fixed up the arguments and call sys_kexec_load. The check really is meant to filter out KEXEC_ARCH_DEFAULT. > This patch takes care of that, I have tested the patch it worked fine for > me. Please review the patch and let me know of your views. This patch is based > on linux-2.6.26-rc3. That patch as it exists is actively bad. It removes the check for a really nasty gotcha if someone passes in KEXEC_ARCH_DEFAULT in 32bit mode. Code expecting a 32bit handoff and getting a 64bit handoff will explode in fun ways. You happened to test the one corner case where this does not matter. What we need to do is fix /sbin/kexec to pass in the correct architecture of the kernel for unload as it does for load. Eric _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec