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=-3.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_GIT autolearn=no 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 D0045ECE588 for ; Tue, 1 Oct 2019 06:58:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A5EE521835 for ; Tue, 1 Oct 2019 06:58:43 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=axtens.net header.i=@axtens.net header.b="oq7mxXzD" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732700AbfJAG6m (ORCPT ); Tue, 1 Oct 2019 02:58:42 -0400 Received: from mail-pl1-f195.google.com ([209.85.214.195]:39200 "EHLO mail-pl1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725777AbfJAG6m (ORCPT ); Tue, 1 Oct 2019 02:58:42 -0400 Received: by mail-pl1-f195.google.com with SMTP id s17so4982779plp.6 for ; Mon, 30 Sep 2019 23:58:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=axtens.net; s=google; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=b5QJN2+41L3WFDMkHvmVhhmne8r1m1bjlvikNn9ZaWo=; b=oq7mxXzD7mktOBQuf3nC3diwM26fudtogiDGDX6nHiqprad5Ms9PG/WgNAgkOdpYfh iYHI/Gmx/fOLELQIWtxsxzpK/ocpF4oay8L/DJwhzBOPrrTF0zp7nmcLM3kV3dSgVNtb rsQsI77ldEJ3T7W4ISMvM6oiCEcGIMrBrYrPE= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=b5QJN2+41L3WFDMkHvmVhhmne8r1m1bjlvikNn9ZaWo=; b=hDACi7FqEYuoIhk6SioiVzAMKv9qvybJJ0E1NR/IjpC/prfa/iDxIYXXJrV8ByOpcg WrftqyPrB1mK2w2uqNYaR3dpSVsZFSFA43udrazqzXmAUB2qs/gUEBpmhWLi1UQNsZ9M 9J1f2KkcgkukOrhx8K6YjQy5HXr3g6VA9tV/k2slzkqpkN8fPzXdH21GOBjHm4vUw7uH G2PcEdlXL6QhApfhayvF0fAj3BmuRqqlV0Cpu1doFdfC8crULx6iGHdvnv/+lpGxAdUV eM500F0ivFdwtmyYXiEMNqhPj/ehEY2v2SnYH1L6dXrpb0oI0zgzHRYkmGW96GkQgTaY a7AQ== X-Gm-Message-State: APjAAAXEwsmQNBAzV0atqRB7IaLtfl1ncZZWJxM9Y44ETN19Q1GLkYlz ZEUv0NmlJAJ+DNwS62fTE67fZg== X-Google-Smtp-Source: APXvYqzqQ2SP4fixuRIKQXyzC5KWE0huLiu20WrA3ePCSN/PC1TpOjbiWo4StEzpxBZdknnQ2lZC0A== X-Received: by 2002:a17:902:ab82:: with SMTP id f2mr24901353plr.220.1569913121508; Mon, 30 Sep 2019 23:58:41 -0700 (PDT) Received: from localhost (ppp167-251-205.static.internode.on.net. [59.167.251.205]) by smtp.gmail.com with ESMTPSA id l62sm21800452pfl.167.2019.09.30.23.58.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 30 Sep 2019 23:58:40 -0700 (PDT) From: Daniel Axtens To: kasan-dev@googlegroups.com, linux-mm@kvack.org, x86@kernel.org, aryabinin@virtuozzo.com, glider@google.com, luto@kernel.org, linux-kernel@vger.kernel.org, mark.rutland@arm.com, dvyukov@google.com, christophe.leroy@c-s.fr Cc: linuxppc-dev@lists.ozlabs.org, gor@linux.ibm.com, Daniel Axtens Subject: [PATCH v8 0/5] kasan: support backing vmalloc space with real shadow memory Date: Tue, 1 Oct 2019 16:58:29 +1000 Message-Id: <20191001065834.8880-1-dja@axtens.net> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Currently, vmalloc space is backed by the early shadow page. This means that kasan is incompatible with VMAP_STACK. This series provides a mechanism to back vmalloc space with real, dynamically allocated memory. I have only wired up x86, because that's the only currently supported arch I can work with easily, but it's very easy to wire up other architectures, and it appears that there is some work-in-progress code to do this on arm64 and s390. This has been discussed before in the context of VMAP_STACK: - https://bugzilla.kernel.org/show_bug.cgi?id=202009 - https://lkml.org/lkml/2018/7/22/198 - https://lkml.org/lkml/2019/7/19/822 In terms of implementation details: Most mappings in vmalloc space are small, requiring less than a full page of shadow space. Allocating a full shadow page per mapping would therefore be wasteful. Furthermore, to ensure that different mappings use different shadow pages, mappings would have to be aligned to KASAN_SHADOW_SCALE_SIZE * PAGE_SIZE. Instead, share backing space across multiple mappings. Allocate a backing page when a mapping in vmalloc space uses a particular page of the shadow region. This page can be shared by other vmalloc mappings later on. We hook in to the vmap infrastructure to lazily clean up unused shadow memory. v1: https://lore.kernel.org/linux-mm/20190725055503.19507-1-dja@axtens.net/ v2: https://lore.kernel.org/linux-mm/20190729142108.23343-1-dja@axtens.net/ Address review comments: - Patch 1: use kasan_unpoison_shadow's built-in handling of ranges that do not align to a full shadow byte - Patch 3: prepopulate pgds rather than faulting things in v3: https://lore.kernel.org/linux-mm/20190731071550.31814-1-dja@axtens.net/ Address comments from Mark Rutland: - kasan_populate_vmalloc is a better name - handle concurrency correctly - various nits and cleanups - relax module alignment in KASAN_VMALLOC case v4: https://lore.kernel.org/linux-mm/20190815001636.12235-1-dja@axtens.net/ Changes to patch 1 only: - Integrate Mark's rework, thanks Mark! - handle the case where kasan_populate_shadow might fail - poision shadow on free, allowing the alloc path to just unpoision memory that it uses v5: https://lore.kernel.org/linux-mm/20190830003821.10737-1-dja@axtens.net/ Address comments from Christophe Leroy: - Fix some issues with my descriptions in commit messages and docs - Dynamically free unused shadow pages by hooking into the vmap book-keeping - Split out the test into a separate patch - Optional patch to track the number of pages allocated - minor checkpatch cleanups v6: https://lore.kernel.org/linux-mm/20190902112028.23773-1-dja@axtens.net/ Properly guard freeing pages in patch 1, drop debugging code. v7: https://lore.kernel.org/linux-mm/20190903145536.3390-1-dja@axtens.net/ Add a TLB flush on freeing, thanks Mark Rutland. Explain more clearly how I think freeing is concurrency-safe. v8: rename kasan_vmalloc/shadow_pages to kasan/vmalloc_shadow_pages Daniel Axtens (5): kasan: support backing vmalloc space with real shadow memory kasan: add test for vmalloc fork: support VMAP_STACK with KASAN_VMALLOC x86/kasan: support KASAN_VMALLOC kasan debug: track pages allocated for vmalloc shadow Documentation/dev-tools/kasan.rst | 63 ++++++++ arch/Kconfig | 9 +- arch/x86/Kconfig | 1 + arch/x86/mm/kasan_init_64.c | 60 ++++++++ include/linux/kasan.h | 31 ++++ include/linux/moduleloader.h | 2 +- include/linux/vmalloc.h | 12 ++ kernel/fork.c | 4 + lib/Kconfig.kasan | 16 +++ lib/test_kasan.c | 26 ++++ mm/kasan/common.c | 230 ++++++++++++++++++++++++++++++ mm/kasan/generic_report.c | 3 + mm/kasan/kasan.h | 1 + mm/vmalloc.c | 45 +++++- 14 files changed, 497 insertions(+), 6 deletions(-) -- 2.20.1