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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 D478EC2B9F4 for ; Mon, 14 Jun 2021 19:22:26 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (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 5F6E3611BE for ; Mon, 14 Jun 2021 19:22:26 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5F6E3611BE Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=eldorado.org.br Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:53918 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lssAD-0000JQ-F4 for qemu-devel@archiver.kernel.org; Mon, 14 Jun 2021 15:22:25 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:41208) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lss4w-0001xW-QG; Mon, 14 Jun 2021 15:16:58 -0400 Received: from [201.28.113.2] (port=35932 helo=outlook.eldorado.org.br) by eggs.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lss4v-0003Sz-BH; Mon, 14 Jun 2021 15:16:58 -0400 Received: from power9a ([10.10.71.235]) by outlook.eldorado.org.br with Microsoft SMTPSVC(8.5.9600.16384); Mon, 14 Jun 2021 16:16:52 -0300 Received: from eldorado.org.br (unknown [10.10.71.235]) by power9a (Postfix) with ESMTP id 67C82800D1A; Mon, 14 Jun 2021 16:16:52 -0300 (-03) From: "Bruno Larsen (billionai)" To: qemu-devel@nongnu.org Subject: [RFC PATCH v2 2/2] target/ppc: make gdb able to translate priviledged addresses Date: Mon, 14 Jun 2021 16:16:30 -0300 Message-Id: <20210614191630.101304-2-bruno.larsen@eldorado.org.br> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20210614191630.101304-1-bruno.larsen@eldorado.org.br> References: <20210614191630.101304-1-bruno.larsen@eldorado.org.br> X-OriginalArrivalTime: 14 Jun 2021 19:16:52.0586 (UTC) FILETIME=[D51494A0:01D76151] X-Host-Lookup-Failed: Reverse DNS lookup failed for 201.28.113.2 (failed) Received-SPF: pass client-ip=201.28.113.2; envelope-from=bruno.larsen@eldorado.org.br; helo=outlook.eldorado.org.br X-Spam_score_int: -6 X-Spam_score: -0.7 X-Spam_bar: / X-Spam_report: (-0.7 / 5.0 requ) BAYES_00=-1.9, PDS_HP_HELO_NORDNS=0.42, RDNS_NONE=0.793, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: farosas@linux.ibm.com, richard.henderson@linaro.org, luis.pires@eldorado.org.br, Greg Kurz , lucas.araujo@eldorado.org.br, fernando.valle@eldorado.org.br, qemu-ppc@nongnu.org, matheus.ferst@eldorado.org.br, david@gibson.dropbear.id.au Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" This patch changes ppc_cpu_get_phys_page_debug so that it is now able to translate both, priviledged and real mode addresses independently of whether the CPU executing it has those permissions This was mentioned by Fabiano as something that would be very useful to help with debugging, but could possibly constitute a security issue if that debug function can be called in some way by prodution code. the solution was implemented such that it would be trivial to wrap it around ifdefs for building only with --enable-debug, for instance, but we are not sure this is the best approach, hence why it is an RFC. Suggested-by: Fabiano Rosas Signed-off-by: Bruno Larsen (billionai) --- target/ppc/mmu_helper.c | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) diff --git a/target/ppc/mmu_helper.c b/target/ppc/mmu_helper.c index 9dcdf88597..41c727c690 100644 --- a/target/ppc/mmu_helper.c +++ b/target/ppc/mmu_helper.c @@ -2947,6 +2947,29 @@ hwaddr ppc_cpu_get_phys_page_debug(CPUState *cs, vaddr addr) cpu_mmu_index(&cpu->env, true), false)) { return raddr & TARGET_PAGE_MASK; } + + /* + * This is a fallback, in case we're asking for priviledged memory to + * be printed, but the PCU is not executing in a priviledged manner. + * + * The code could be considered a security vulnerability if + * this function can be called in a scenario that does not involve + * debugging. + * Given the name and how useful using real addresses may be for + * actually debugging, however, we decided to include it anyway and + * discuss how to best avoid the possible security concerns. + * The current plan is that, if there is a chance this code is called in + * a production environment, we can surround it with ifdefs so that it + * is only compiled with --enable-debug + */ + /* attempt to translate first with virtual addresses */ + if (ppc_xlate(cpu, addr, MMU_DATA_LOAD, &raddr, &s, &p, 1, false) || + ppc_xlate(cpu, addr, MMU_INST_FETCH, &raddr, &s, &p, 1, false) || + /* if didn't work, attempt to translate with real addresses */ + ppc_xlate(cpu, addr, MMU_DATA_LOAD, &raddr, &s, &p, 3, false) || + ppc_xlate(cpu, addr, MMU_INST_FETCH, &raddr, &s, &p, 3, false)) { + return raddr & TARGET_PAGE_MASK; + } return -1; } -- 2.17.1