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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=unavailable 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 28071C0650F for ; Thu, 8 Aug 2019 08:40:06 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id 3C993217F4 for ; Thu, 8 Aug 2019 08:40:00 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3C993217F4 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-16758-kernel-hardening=archiver.kernel.org@lists.openwall.com Received: (qmail 31933 invoked by uid 550); 8 Aug 2019 08:39:53 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Received: (qmail 31855 invoked from network); 8 Aug 2019 08:39:51 -0000 Subject: Re: [PATCH v5 10/10] powerpc/fsl_booke/kaslr: dump out kernel offset information on panic To: Michael Ellerman , , , , , , , , CC: , , , , , , References: <20190807065706.11411-1-yanaijie@huawei.com> <20190807065706.11411-11-yanaijie@huawei.com> <87zhklt9eg.fsf@concordia.ellerman.id.au> From: Jason Yan Message-ID: <9113cc5b-0e89-f423-712a-79220af82b92@huawei.com> Date: Thu, 8 Aug 2019 16:39:26 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.5.0 MIME-Version: 1.0 In-Reply-To: <87zhklt9eg.fsf@concordia.ellerman.id.au> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.177.96.203] X-CFilter-Loop: Reflected On 2019/8/7 21:03, Michael Ellerman wrote: > Jason Yan writes: >> When kaslr is enabled, the kernel offset is different for every boot. >> This brings some difficult to debug the kernel. Dump out the kernel >> offset when panic so that we can easily debug the kernel. > > Some of this is taken from the arm64 version right? Please say so when > you copy other people's code. > No problem. Architectures like x86 or arm64 or s390 both have this similar code. I guess x86 is the first one. >> diff --git a/arch/powerpc/kernel/machine_kexec.c b/arch/powerpc/kernel/machine_kexec.c >> index c4ed328a7b96..078fe3d76feb 100644 >> --- a/arch/powerpc/kernel/machine_kexec.c >> +++ b/arch/powerpc/kernel/machine_kexec.c >> @@ -86,6 +86,7 @@ void arch_crash_save_vmcoreinfo(void) >> VMCOREINFO_STRUCT_SIZE(mmu_psize_def); >> VMCOREINFO_OFFSET(mmu_psize_def, shift); >> #endif >> + vmcoreinfo_append_str("KERNELOFFSET=%lx\n", kaslr_offset()); >> } > > There's no mention of that in the commit log. > > Please split it into a separate patch and describe what you're doing and > why. OK > >> diff --git a/arch/powerpc/kernel/setup-common.c b/arch/powerpc/kernel/setup-common.c >> index 1f8db666468d..064075f02837 100644 >> --- a/arch/powerpc/kernel/setup-common.c >> +++ b/arch/powerpc/kernel/setup-common.c >> @@ -715,12 +715,31 @@ static struct notifier_block ppc_panic_block = { >> .priority = INT_MIN /* may not return; must be done last */ >> }; >> >> +/* >> + * Dump out kernel offset information on panic. >> + */ >> +static int dump_kernel_offset(struct notifier_block *self, unsigned long v, >> + void *p) >> +{ >> + pr_emerg("Kernel Offset: 0x%lx from 0x%lx\n", >> + kaslr_offset(), KERNELBASE); >> + >> + return 0; >> +} >> + >> +static struct notifier_block kernel_offset_notifier = { >> + .notifier_call = dump_kernel_offset >> +}; >> + >> void __init setup_panic(void) >> { >> /* PPC64 always does a hard irq disable in its panic handler */ >> if (!IS_ENABLED(CONFIG_PPC64) && !ppc_md.panic) >> return; >> atomic_notifier_chain_register(&panic_notifier_list, &ppc_panic_block); > >> + if (IS_ENABLED(CONFIG_RANDOMIZE_BASE) && kaslr_offset() > 0) >> + atomic_notifier_chain_register(&panic_notifier_list, >> + &kernel_offset_notifier); > > Don't you want to do that before the return above? > Eagle eye. This should not affected by the conditions above. >> } > > cheers > > . >