From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 837DFC3F2D1 for ; Mon, 2 Mar 2020 03:30:08 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 3C3D52073B for ; Mon, 2 Mar 2020 03:30:08 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3C3D52073B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=buserror.net Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 48W5Hd0PnKzDqcg for ; Mon, 2 Mar 2020 14:30:05 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; spf=none (no SPF record) smtp.mailfrom=buserror.net (client-ip=165.227.176.147; helo=baldur.buserror.net; envelope-from=oss@buserror.net; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=buserror.net Received: from baldur.buserror.net (baldur.buserror.net [165.227.176.147]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 48W5Fq0cPczDq77 for ; Mon, 2 Mar 2020 14:28:30 +1100 (AEDT) Received: from [2601:449:8480:af0:12bf:48ff:fe84:c9a0] by baldur.buserror.net with esmtpsa (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1j8bgX-0000KG-Ui; Sun, 01 Mar 2020 21:24:02 -0600 Message-ID: <31b5966ba579ef246176a7d8ad18c2c02788dd27.camel@buserror.net> From: Scott Wood To: Jason Yan , Daniel Axtens , mpe@ellerman.id.au, linuxppc-dev@lists.ozlabs.org, diana.craciun@nxp.com, christophe.leroy@c-s.fr, benh@kernel.crashing.org, paulus@samba.org, npiggin@gmail.com, keescook@chromium.org, kernel-hardening@lists.openwall.com, me@tobin.cc Date: Sun, 01 Mar 2020 21:24:00 -0600 In-Reply-To: <35e6c660-3896-bdb8-45f3-c1504aa2171f@huawei.com> References: <20200206025825.22934-1-yanaijie@huawei.com> <87tv3drf79.fsf@dja-thinkpad.axtens.net> <8171d326-5138-4f5c-cff6-ad3ee606f0c2@huawei.com> <4c0e7fec63dbc7b91fa6c24692c73c256c131f51.camel@buserror.net> <188971ed-f1c4-39b3-c07e-89cc593d88d7@huawei.com> <530c49dfd97c811dc53ffc78c594d7133f7eb1e9.camel@buserror.net> <35e6c660-3896-bdb8-45f3-c1504aa2171f@huawei.com> Organization: Red Hat Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.28.5-0ubuntu0.18.04.1 Mime-Version: 1.0 Content-Transfer-Encoding: 8bit X-SA-Exim-Connect-IP: 2601:449:8480:af0:12bf:48ff:fe84:c9a0 X-SA-Exim-Rcpt-To: yanaijie@huawei.com, dja@axtens.net, mpe@ellerman.id.au, linuxppc-dev@lists.ozlabs.org, diana.craciun@nxp.com, christophe.leroy@c-s.fr, benh@kernel.crashing.org, paulus@samba.org, npiggin@gmail.com, keescook@chromium.org, kernel-hardening@lists.openwall.com, me@tobin.cc, linux-kernel@vger.kernel.org, zhaohongjiang@huawei.com X-SA-Exim-Mail-From: oss@buserror.net Subject: Re: [PATCH v3 0/6] implement KASLR for powerpc/fsl_booke/64 X-SA-Exim-Version: 4.2.1 (built Tue, 02 Aug 2016 21:08:31 +0000) X-SA-Exim-Scanned: Yes (on baldur.buserror.net) X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-kernel@vger.kernel.org, zhaohongjiang@huawei.com Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Mon, 2020-03-02 at 10:17 +0800, Jason Yan wrote: > > 在 2020/3/1 6:54, Scott Wood 写道: > > On Sat, 2020-02-29 at 15:27 +0800, Jason Yan wrote: > > > > > > Turnning to %p may not be a good idea in this situation. So > > > for the REG logs printed when dumping stack, we can disable it when > > > KASLR is open. For the REG logs in other places like show_regs(), only > > > privileged can trigger it, and they are not combind with a symbol, so > > > I think it's ok to keep them. > > > > > > diff --git a/arch/powerpc/kernel/process.c > > > b/arch/powerpc/kernel/process.c > > > index fad50db9dcf2..659c51f0739a 100644 > > > --- a/arch/powerpc/kernel/process.c > > > +++ b/arch/powerpc/kernel/process.c > > > @@ -2068,7 +2068,10 @@ void show_stack(struct task_struct *tsk, unsigned > > > long *stack) > > > newsp = stack[0]; > > > ip = stack[STACK_FRAME_LR_SAVE]; > > > if (!firstframe || ip != lr) { > > > - printk("["REG"] ["REG"] %pS", sp, ip, (void > > > *)ip); > > > + if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) > > > + printk("%pS", (void *)ip); > > > + else > > > + printk("["REG"] ["REG"] %pS", sp, ip, > > > (void *)ip); > > > > This doesn't deal with "nokaslr" on the kernel command line. It also > > doesn't > > seem like something that every callsite should have to opencode, versus > > having > > an appropriate format specifier behaves as I described above (and I still > > don't see why that format specifier should not be "%p"). > > > > Actually I still do not understand why we should print the raw value > here. When KALLSYMS is enabled we have symbol name and offset like > put_cred_rcu+0x108/0x110, and when KALLSYMS is disabled we have the raw > address. I'm more concerned about the stack address for wading through a raw stack dump (to find function call arguments, etc). The return address does help confirm that I'm on the right stack frame though, and also makes looking up a line number slightly easier than having to look up a symbol address and then add the offset (at least for non-module addresses). As a random aside, the mismatch between Linux printing a hex offset and GDB using decimal in disassembly is annoying... -Scott