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=-18.8 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,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 AD2DDC48BE5 for ; Thu, 17 Jun 2021 06:40:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 953EF613FE for ; Thu, 17 Jun 2021 06:40:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230242AbhFQGmS (ORCPT ); Thu, 17 Jun 2021 02:42:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43240 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229709AbhFQGmQ (ORCPT ); Thu, 17 Jun 2021 02:42:16 -0400 Received: from mail-pj1-x1036.google.com (mail-pj1-x1036.google.com [IPv6:2607:f8b0:4864:20::1036]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 516E5C061574 for ; Wed, 16 Jun 2021 23:40:09 -0700 (PDT) Received: by mail-pj1-x1036.google.com with SMTP id fy24-20020a17090b0218b029016c5a59021fso5528253pjb.0 for ; Wed, 16 Jun 2021 23:40:09 -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:in-reply-to:references :mime-version:content-transfer-encoding; bh=FhcxQma+NItwG5Mp37m/KF4tp14MA8dMkKZlGGIww7w=; b=NX/qvxr8dhuE37o1z5sgt2XG3iamjEnXiWs3Cjuob6iS4N7i54VKlfizgYe8xGGkPG ECD5YCGaTs51KaCl4epayh0dHJ+o8LndpifLgVU7jrsZXsK+fxf956QA+f9kaEQexM97 ESKPsh4uIbJJ1pXHDwjoTPF3Wsz2Knn+hfVYc= 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:in-reply-to :references:mime-version:content-transfer-encoding; bh=FhcxQma+NItwG5Mp37m/KF4tp14MA8dMkKZlGGIww7w=; b=KW5NXjn0tuqBhL2U2yGkc10yWZIC2G/+06ikQCCvZmzGWd4qTzPlICe2m2mdu3hnPh VYKkNf/1DtTH7/znysUG7R9OSxnHBINQI9ap3KcIUd5yE2YyiE0I5dW24VhvTshOyQgd lHh4+X/KN4FAG8jOX/dUKcXjBM2W18RT+4sXeDKxgmCbrWZdPF0ydQUXo+zNARopaxVc BHWm/NNZykZ4fjamYRnHL7OIrbaZxsy2VeD+x16owubni1u+LKmawwVtlwenOyjB5mWH S6FenoJHug+Ar+i5s3Sts82/GsmZ59qOuqeFCgAzPxQUVHHproNXYpw6gHre7p+Mg5fH Z3wQ== X-Gm-Message-State: AOAM532Xr/IHTkPSIIkb7CASd5wRTNwqHynfYPKizvZHA2tbjpP7WArl 3kJa1D6BbcI9PXuIDASD/4d27MzrMVWkSQ== X-Google-Smtp-Source: ABdhPJzfeN5byN4YxzyNu/GjCulyBlU25iQrctXCoCFZvJ5L0B+A23QQj4gHY87HwYK24nhSnOkqEg== X-Received: by 2002:a17:90b:38ca:: with SMTP id nn10mr4147573pjb.127.1623912008754; Wed, 16 Jun 2021 23:40:08 -0700 (PDT) Received: from localhost ([203.206.29.204]) by smtp.gmail.com with ESMTPSA id d12sm3987316pfo.113.2021.06.16.23.40.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 16 Jun 2021 23:40:08 -0700 (PDT) From: Daniel Axtens To: linux-kernel@vger.kernel.org, linux-mm@kvack.org, kasan-dev@googlegroups.com, elver@google.com, akpm@linux-foundation.org, andreyknvl@gmail.com Cc: linuxppc-dev@lists.ozlabs.org, christophe.leroy@csgroup.eu, aneesh.kumar@linux.ibm.com, bsingharora@gmail.com, Daniel Axtens Subject: [PATCH v14 1/4] kasan: allow an architecture to disable inline instrumentation Date: Thu, 17 Jun 2021 16:39:53 +1000 Message-Id: <20210617063956.94061-2-dja@axtens.net> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210617063956.94061-1-dja@axtens.net> References: <20210617063956.94061-1-dja@axtens.net> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org For annoying architectural reasons, it's very difficult to support inline instrumentation on powerpc64.* Add a Kconfig flag to allow an arch to disable inline. (It's a bit annoying to be 'backwards', but I'm not aware of any way to have an arch force a symbol to be 'n', rather than 'y'.) We also disable stack instrumentation in this case as it does things that are functionally equivalent to inline instrumentation, namely adding code that touches the shadow directly without going through a C helper. * on ppc64 atm, the shadow lives in virtual memory and isn't accessible in real mode. However, before we turn on virtual memory, we parse the device tree to determine which platform and MMU we're running under. That calls generic DT code, which is instrumented. Inline instrumentation in DT would unconditionally attempt to touch the shadow region, which we won't have set up yet, and would crash. We can make outline mode wait for the arch to be ready, but we can't change what the compiler inserts for inline mode. Signed-off-by: Daniel Axtens --- lib/Kconfig.kasan | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan index cffc2ebbf185..cb5e02d09e11 100644 --- a/lib/Kconfig.kasan +++ b/lib/Kconfig.kasan @@ -12,6 +12,15 @@ config HAVE_ARCH_KASAN_HW_TAGS config HAVE_ARCH_KASAN_VMALLOC bool +config ARCH_DISABLE_KASAN_INLINE + bool + help + Sometimes an architecture might not be able to support inline + instrumentation but might be able to support outline instrumentation. + This option allows an architecture to prevent inline and stack + instrumentation from being enabled. + + config CC_HAS_KASAN_GENERIC def_bool $(cc-option, -fsanitize=kernel-address) @@ -130,6 +139,7 @@ config KASAN_OUTLINE config KASAN_INLINE bool "Inline instrumentation" + depends on !ARCH_DISABLE_KASAN_INLINE help Compiler directly inserts code checking shadow memory before memory accesses. This is faster than outline (in some workloads @@ -141,6 +151,7 @@ endchoice config KASAN_STACK bool "Enable stack instrumentation (unsafe)" if CC_IS_CLANG && !COMPILE_TEST depends on KASAN_GENERIC || KASAN_SW_TAGS + depends on !ARCH_DISABLE_KASAN_INLINE default y if CC_IS_GCC help The LLVM stack address sanitizer has a know problem that @@ -154,6 +165,9 @@ config KASAN_STACK but clang users can still enable it for builds without CONFIG_COMPILE_TEST. On gcc it is assumed to always be safe to use and enabled by default. + If the architecture disables inline instrumentation, this is + also disabled as it adds inline-style instrumentation that + is run unconditionally. config KASAN_SW_TAGS_IDENTIFY bool "Enable memory corruption identification" -- 2.30.2