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=-8.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,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 512A6C433FF for ; Mon, 29 Jul 2019 11:43:24 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id A02A9214AE for ; Mon, 29 Jul 2019 11:43:23 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=c-s.fr header.i=@c-s.fr header.b="gQcd8A2m" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A02A9214AE Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=c-s.fr Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-16609-kernel-hardening=archiver.kernel.org@lists.openwall.com Received: (qmail 3211 invoked by uid 550); 29 Jul 2019 11:43:17 -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 3176 invoked from network); 29 Jul 2019 11:43:17 -0000 Authentication-Results: localhost; dkim=pass reason="1024-bit key; insecure key" header.d=c-s.fr header.i=@c-s.fr header.b=gQcd8A2m; dkim-adsp=pass; dkim-atps=neutral X-Virus-Scanned: Debian amavisd-new at c-s.fr DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=c-s.fr; s=mail; t=1564400580; bh=oyTcdJNswUMDP85sX5v7WcFP0jGM+1wacBk208oBdos=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=gQcd8A2mgPsRb+PIAyRhLetcCz0LLtGz1/v84rb68LV0YpwKzJ4Ez6uevgVuNatIF QTqTw+FNpqe/Md6U6n/bzZAqsEkPRUyjPlRMfsNzPX3dHGum6XXqWXMFcbEHPvdYps G1/BTzbVQ9tgujtAfeyjWzniwt4eXV5whFs6SGe0= X-Virus-Scanned: amavisd-new at c-s.fr Subject: Re: [RFC PATCH 10/10] powerpc/fsl_booke/kaslr: dump out kernel offset information on panic To: Jason Yan , mpe@ellerman.id.au, linuxppc-dev@lists.ozlabs.org, diana.craciun@nxp.com, benh@kernel.crashing.org, paulus@samba.org, npiggin@gmail.com, keescook@chromium.org, kernel-hardening@lists.openwall.com Cc: linux-kernel@vger.kernel.org, wangkefeng.wang@huawei.com, yebin10@huawei.com, thunder.leizhen@huawei.com, jingxiangfeng@huawei.com, fanchengyang@huawei.com References: <20190717080621.40424-1-yanaijie@huawei.com> <20190717080621.40424-11-yanaijie@huawei.com> From: Christophe Leroy Message-ID: Date: Mon, 29 Jul 2019 13:43:05 +0200 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190717080621.40424-11-yanaijie@huawei.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: fr Content-Transfer-Encoding: 8bit Archived-At: List-Archive: Le 17/07/2019 à 10:06, Jason Yan a écrit : > 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. > > Signed-off-by: Jason Yan > Cc: Diana Craciun > Cc: Michael Ellerman > Cc: Christophe Leroy > Cc: Benjamin Herrenschmidt > Cc: Paul Mackerras > Cc: Nicholas Piggin > Cc: Kees Cook > --- > arch/powerpc/include/asm/page.h | 5 +++++ > arch/powerpc/kernel/machine_kexec.c | 1 + > arch/powerpc/kernel/setup-common.c | 23 +++++++++++++++++++++++ > 3 files changed, 29 insertions(+) > > diff --git a/arch/powerpc/include/asm/page.h b/arch/powerpc/include/asm/page.h > index 60a68d3a54b1..cd3ac530e58d 100644 > --- a/arch/powerpc/include/asm/page.h > +++ b/arch/powerpc/include/asm/page.h > @@ -317,6 +317,11 @@ struct vm_area_struct; > > extern unsigned long kimage_vaddr; > > +static inline unsigned long kaslr_offset(void) > +{ > + return kimage_vaddr - KERNELBASE; > +} > + > #include > #endif /* __ASSEMBLY__ */ > #include > 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()); > } > > /* > diff --git a/arch/powerpc/kernel/setup-common.c b/arch/powerpc/kernel/setup-common.c > index 1f8db666468d..49e540c0adeb 100644 > --- a/arch/powerpc/kernel/setup-common.c > +++ b/arch/powerpc/kernel/setup-common.c > @@ -715,12 +715,35 @@ 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) > +{ > + const unsigned long offset = kaslr_offset(); > + > + if (IS_ENABLED(CONFIG_RANDOMIZE_BASE) && offset > 0) > + pr_emerg("Kernel Offset: 0x%lx from 0x%lx\n", > + offset, KERNELBASE); > + else > + pr_emerg("Kernel Offset: disabled\n"); Do we really need that else branch ? Why not just make the below atomic_notifier_chain_register() conditionnal to IS_ENABLED(CONFIG_RANDOMIZE_BASE) && offset > 0 and not print anything otherwise ? Christophe > + > + 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); > + atomic_notifier_chain_register(&panic_notifier_list, > + &kernel_offset_notifier); > } > > #ifdef CONFIG_CHECK_CACHE_COHERENCY >