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=-15.7 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=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 80657C433ED for ; Fri, 30 Apr 2021 06:00:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 614ED61463 for ; Fri, 30 Apr 2021 06:00:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229591AbhD3GBN (ORCPT ); Fri, 30 Apr 2021 02:01:13 -0400 Received: from mail.kernel.org ([198.145.29.99]:54312 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230313AbhD3GBB (ORCPT ); Fri, 30 Apr 2021 02:01:01 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 5962F61490; Fri, 30 Apr 2021 06:00:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1619762413; bh=qiLsPPa5nZWq8AaAdTxN4m1i4hKBFPRt6kXjnVRzH3E=; h=Date:From:To:Subject:In-Reply-To:From; b=GhuGJ3l4z5H1oFvpBFpbiRAFN9Dv/vX8GteGkEEPvFgqJB6fzcvxltSTcDChByQ03 Q07sVKZrAWwsOH7jupLOt9EVjDdx0HiL0dIiuOTRz5B3SDo1mNQ3hz8rzH/MyCP+Ig u8OyeGOpdN0uz3aNFob9BoG/JS34lOCtzSAxrO8I= Date: Thu, 29 Apr 2021 23:00:12 -0700 From: Andrew Morton To: akpm@linux-foundation.org, andreyknvl@google.com, aryabinin@virtuozzo.com, dvyukov@google.com, elver@google.com, glider@google.com, linux-mm@kvack.org, mm-commits@vger.kernel.org, torvalds@linux-foundation.org Subject: [patch 136/178] kasan: docs: clean up sections Message-ID: <20210430060012.T5cGRItT8%akpm@linux-foundation.org> In-Reply-To: <20210429225251.02b6386d21b69255b4f6c163@linux-foundation.org> User-Agent: s-nail v14.8.16 Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org From: Andrey Konovalov Subject: kasan: docs: clean up sections Update KASAN documentation: - Give some sections clearer names. - Remove unneeded subsections in the "Tests" section. - Move the "For developers" section and split into subsections. Link: https://lkml.kernel.org/r/c2bbb56eaea80ad484f0ee85bb71959a3a63f1d7.1615559068.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov Reviewed-by: Marco Elver Cc: Alexander Potapenko Cc: Andrey Ryabinin Cc: Dmitry Vyukov Signed-off-by: Andrew Morton --- Documentation/dev-tools/kasan.rst | 54 ++++++++++++++-------------- 1 file changed, 27 insertions(+), 27 deletions(-) --- a/Documentation/dev-tools/kasan.rst~kasan-docs-clean-up-sections +++ a/Documentation/dev-tools/kasan.rst @@ -177,24 +177,6 @@ particular KASAN features. report or also panic the kernel (default: ``report``). Note, that tag checking gets disabled after the first reported bug. -For developers -~~~~~~~~~~~~~~ - -Software KASAN modes use compiler instrumentation to insert validity checks. -Such instrumentation might be incompatible with some part of the kernel, and -therefore needs to be disabled. To disable instrumentation for specific files -or directories, add a line similar to the following to the respective kernel -Makefile: - -- For a single file (e.g. main.o):: - - KASAN_SANITIZE_main.o := n - -- For all files in one directory:: - - KASAN_SANITIZE := n - - Implementation details ---------------------- @@ -308,8 +290,8 @@ support MTE (but supports TBI). Hardware tag-based KASAN only reports the first found bug. After that MTE tag checking gets disabled. -What memory accesses are sanitised by KASAN? --------------------------------------------- +Shadow memory +------------- The kernel maps memory in a number of different parts of the address space. This poses something of a problem for KASAN, which requires @@ -320,8 +302,8 @@ The range of kernel virtual addresses is real memory to support a real shadow region for every address that could be accessed by the kernel. -By default -~~~~~~~~~~ +Default behaviour +~~~~~~~~~~~~~~~~~ By default, architectures only map real memory over the shadow region for the linear mapping (and potentially other small areas). For all @@ -371,8 +353,29 @@ unmapped. This will require changes in a This allows ``VMAP_STACK`` support on x86, and can simplify support of architectures that do not have a fixed module region. -CONFIG_KASAN_KUNIT_TEST and CONFIG_KASAN_MODULE_TEST ----------------------------------------------------- +For developers +-------------- + +Ignoring accesses +~~~~~~~~~~~~~~~~~ + +Software KASAN modes use compiler instrumentation to insert validity checks. +Such instrumentation might be incompatible with some part of the kernel, and +therefore needs to be disabled. To disable instrumentation for specific files +or directories, add a line similar to the following to the respective kernel +Makefile: + +- For a single file (e.g. main.o):: + + KASAN_SANITIZE_main.o := n + +- For all files in one directory:: + + KASAN_SANITIZE := n + + +Tests +~~~~~ KASAN tests consist of two parts: @@ -418,21 +421,18 @@ Or, if one of the tests failed:: There are a few ways to run KUnit-compatible KASAN tests. 1. Loadable module -~~~~~~~~~~~~~~~~~~ With ``CONFIG_KUNIT`` enabled, ``CONFIG_KASAN_KUNIT_TEST`` can be built as a loadable module and run on any architecture that supports KASAN by loading the module with insmod or modprobe. The module is called ``test_kasan``. 2. Built-In -~~~~~~~~~~~ With ``CONFIG_KUNIT`` built-in, ``CONFIG_KASAN_KUNIT_TEST`` can be built-in on any architecure that supports KASAN. These and any other KUnit tests enabled will run and print the results at boot as a late-init call. 3. Using kunit_tool -~~~~~~~~~~~~~~~~~~~ With ``CONFIG_KUNIT`` and ``CONFIG_KASAN_KUNIT_TEST`` built-in, it's also possible use ``kunit_tool`` to see the results of these and other KUnit tests _