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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 BDF58C433E0 for ; Tue, 9 Feb 2021 21:42:07 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 4AC5064ECE for ; Tue, 9 Feb 2021 21:42:07 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4AC5064ECE Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id D6E716B0072; Tue, 9 Feb 2021 16:42:06 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id D1E796B0073; Tue, 9 Feb 2021 16:42:06 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C5B836B0074; Tue, 9 Feb 2021 16:42:06 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0114.hostedemail.com [216.40.44.114]) by kanga.kvack.org (Postfix) with ESMTP id A7D0D6B0072 for ; Tue, 9 Feb 2021 16:42:06 -0500 (EST) Received: from smtpin05.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 704E3160D0 for ; Tue, 9 Feb 2021 21:42:06 +0000 (UTC) X-FDA: 77800052652.05.pig29_50043512760a Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin05.hostedemail.com (Postfix) with ESMTP id 430F5185E286B for ; Tue, 9 Feb 2021 21:42:06 +0000 (UTC) X-HE-Tag: pig29_50043512760a X-Filterd-Recvd-Size: 4530 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf38.hostedemail.com (Postfix) with ESMTP for ; Tue, 9 Feb 2021 21:42:05 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id EEF2264ECD; Tue, 9 Feb 2021 21:42:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1612906924; bh=xZSowleWtaeqZhTcDcTbm/BmRYYIaEdtQV2EpoetsNs=; h=Date:From:To:Subject:In-Reply-To:From; b=nV+9eYMoxV4NqeQMiHsE9JGOu1mmKzHislOrDKf4XaEgjllLvSdR4ykFOWOS57QJg EiEz7zomJ7pGjYWl2NU6LbMzV7rsioX9S+qB/xSQ8EUd5aIeRGgEVaedQhSruhoSA3 x8k+lyWyg/jTIkgcutit3hb2im/uyQXlduEyN2CI= Date: Tue, 09 Feb 2021 13:42:03 -0800 From: Andrew Morton To: akpm@linux-foundation.org, andreyknvl@google.com, aryabinin@virtuozzo.com, Branislav.Rankov@arm.com, catalin.marinas@arm.com, dvyukov@google.com, elver@google.com, eugenis@google.com, glider@google.com, kevin.brodsky@arm.com, linux-mm@kvack.org, mm-commits@vger.kernel.org, pcc@google.com, torvalds@linux-foundation.org, vincenzo.frascino@arm.com, will.deacon@arm.com Subject: [patch 05/14] kasan: fix stack traces dependency for HW_TAGS Message-ID: <20210209214203.tt68YEBnH%akpm@linux-foundation.org> In-Reply-To: <20210209134115.4d933d446165cd0ed8977b03@linux-foundation.org> User-Agent: s-nail v14.8.16 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: Andrey Konovalov Subject: kasan: fix stack traces dependency for HW_TAGS Currently, whether the alloc/free stack traces collection is enabled by default for hardware tag-based KASAN depends on CONFIG_DEBUG_KERNEL. The intention for this dependency was to only enable collection on slow debug kernels due to a significant perf and memory impact. As it turns out, CONFIG_DEBUG_KERNEL is not considered a debug option and is enabled on many productions kernels including Android and Ubuntu. As the result, this dependency is pointless and only complicates the code and documentation. Having stack traces collection disabled by default would make the hardware mode work differently to to the software ones, which is confusing. This change removes the dependency and enables stack traces collection by default. Looking into the future, this default might makes sense for production kernels, assuming we implement a fast stack trace collection approach. Link: https://lkml.kernel.org/r/6678d77ceffb71f1cff2cf61560e2ffe7bb6bfe9.1612808820.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov Reviewed-by: Marco Elver Cc: Catalin Marinas Cc: Vincenzo Frascino Cc: Dmitry Vyukov Cc: Alexander Potapenko Cc: Will Deacon Cc: Andrey Ryabinin Cc: Peter Collingbourne Cc: Evgenii Stepanov Cc: Branislav Rankov Cc: Kevin Brodsky Signed-off-by: Andrew Morton --- Documentation/dev-tools/kasan.rst | 3 +-- mm/kasan/hw_tags.c | 8 ++------ 2 files changed, 3 insertions(+), 8 deletions(-) --- a/Documentation/dev-tools/kasan.rst~kasan-fix-stack-traces-dependency-for-hw_tags +++ a/Documentation/dev-tools/kasan.rst @@ -163,8 +163,7 @@ particular KASAN features. - ``kasan=off`` or ``=on`` controls whether KASAN is enabled (default: ``on``). - ``kasan.stacktrace=off`` or ``=on`` disables or enables alloc and free stack - traces collection (default: ``on`` for ``CONFIG_DEBUG_KERNEL=y``, otherwise - ``off``). + traces collection (default: ``on``). - ``kasan.fault=report`` or ``=panic`` controls whether to only print a KASAN report or also panic the kernel (default: ``report``). --- a/mm/kasan/hw_tags.c~kasan-fix-stack-traces-dependency-for-hw_tags +++ a/mm/kasan/hw_tags.c @@ -134,12 +134,8 @@ void __init kasan_init_hw_tags(void) switch (kasan_arg_stacktrace) { case KASAN_ARG_STACKTRACE_DEFAULT: - /* - * Default to enabling stack trace collection for - * debug kernels. - */ - if (IS_ENABLED(CONFIG_DEBUG_KERNEL)) - static_branch_enable(&kasan_flag_stacktrace); + /* Default to enabling stack trace collection. */ + static_branch_enable(&kasan_flag_stacktrace); break; case KASAN_ARG_STACKTRACE_OFF: /* Do nothing, kasan_flag_stacktrace keeps its default value. */ _