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=-9.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 12010C433DF for ; Tue, 16 Jun 2020 02:25:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F36E920768 for ; Tue, 16 Jun 2020 02:25:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726718AbgFPCZt (ORCPT ); Mon, 15 Jun 2020 22:25:49 -0400 Received: from foss.arm.com ([217.140.110.172]:58052 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726101AbgFPCZt (ORCPT ); Mon, 15 Jun 2020 22:25:49 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 1ED4F1FB; Mon, 15 Jun 2020 19:25:48 -0700 (PDT) Received: from p8cg001049571a15.arm.com (unknown [10.163.80.105]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 219B33F71F; Mon, 15 Jun 2020 19:25:44 -0700 (PDT) From: Anshuman Khandual To: linux-arm-kernel@lists.infradead.org Cc: Anshuman Khandual , Catalin Marinas , Will Deacon , Suzuki K Poulose , Mark Brown , Mark Rutland , linux-kernel@vger.kernel.org Subject: [PATCH] arm64/cpufeature: Validate feature bits spacing in arm64_ftr_regs[] Date: Tue, 16 Jun 2020 07:55:31 +0530 Message-Id: <1592274331-19006-1-git-send-email-anshuman.khandual@arm.com> X-Mailer: git-send-email 2.7.4 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org arm64_feature_bits for a register in arm64_ftr_regs[] are in a descending order as per their shift values. Validate that these features bits are defined correctly and do not overlap with each other. This check protects against any inadvertent erroneous changes to the register definitions. Cc: Catalin Marinas Cc: Will Deacon Cc: Suzuki K Poulose Cc: Mark Brown Cc: Mark Rutland Cc: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Anshuman Khandual --- Applies on 5.8-rc1. arch/arm64/kernel/cpufeature.c | 45 +++++++++++++++++++++++++++++++--- 1 file changed, 42 insertions(+), 3 deletions(-) diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index 4ae41670c2e6..2270eda9a7fb 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -697,11 +697,50 @@ static s64 arm64_ftr_safe_value(const struct arm64_ftr_bits *ftrp, s64 new, static void __init sort_ftr_regs(void) { - int i; + const struct arm64_ftr_reg *ftr_reg; + const struct arm64_ftr_bits *ftr_bits; + unsigned int i, j, width, shift, prev_shift; + + for (i = 0; i < ARRAY_SIZE(arm64_ftr_regs); i++) { + /* + * Features here must be sorted in descending order with respect + * to their shift values and should not overlap with each other. + */ + ftr_reg = arm64_ftr_regs[i].reg; + for (ftr_bits = ftr_reg->ftr_bits, j = 0; + ftr_bits->width != 0; ftr_bits++, j++) { + if (WARN_ON(ftr_bits->shift + ftr_bits->width > 64)) + pr_err("%s has invalid feature at shift %d\n", + ftr_reg->name, ftr_bits->shift); + + /* + * Skip the first feature. There is nothing to + * compare against for now. + */ + if (j == 0) + continue; + + prev_shift = ftr_reg->ftr_bits[j - 1].shift; + width = ftr_reg->ftr_bits[j].width; + shift = ftr_reg->ftr_bits[j].shift; + if (WARN_ON(prev_shift < shift + width)) + pr_err("%s has feature overlap at shift %d\n", + ftr_reg->name, ftr_bits->shift); + } - /* Check that the array is sorted so that we can do the binary search */ - for (i = 1; i < ARRAY_SIZE(arm64_ftr_regs); i++) + /* + * Skip the first register. There is nothing to + * compare against for now. + */ + if (i == 0) + continue; + /* + * Registers here must be sorted in ascending order with respect + * to sys_id for subsequent binary search in get_arm64_ftr_reg() + * to work correctly. + */ BUG_ON(arm64_ftr_regs[i].sys_id < arm64_ftr_regs[i - 1].sys_id); + } } /* -- 2.20.1