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,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 2AE07C48BE6 for ; Wed, 16 Jun 2021 08:02:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0DF4161159 for ; Wed, 16 Jun 2021 08:02:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232038AbhFPIFC (ORCPT ); Wed, 16 Jun 2021 04:05:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50102 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232054AbhFPIFA (ORCPT ); Wed, 16 Jun 2021 04:05:00 -0400 Received: from mail-pj1-x1034.google.com (mail-pj1-x1034.google.com [IPv6:2607:f8b0:4864:20::1034]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 85EE5C061760 for ; Wed, 16 Jun 2021 01:02:54 -0700 (PDT) Received: by mail-pj1-x1034.google.com with SMTP id k5so1252953pjj.1 for ; Wed, 16 Jun 2021 01:02:54 -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=hJE2AePhitLJVg38bm97ceVZi5FIj9UG7cAFa6I89qpLoHOqs1eZo/sgHrTjHCz5vc Z0OB2QrJBz1ePSDeeTBoNAwwTmCWMao+fbzv6i6nf+j/nn2Z/6pH2J/atzq4c7e26OtD 9Ge5u0WlHxE6DHdxeFWDpzw27Ij3DBzy52+fg= 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=WXLN4yurDvcQjmxjHZCkGWqpVYppLKfS7UCJFcIRIauH6Boa+wgnqkD1+wNUWJ+Gwm v8jzohmiTVjiggOdOzCuKogADaas99SkowqeT3GuDXVlfyM3l6lOvRI3vIQE7aWRH+qw 2bGcb1a5pbyJjEzjuhQ18rx26rOBuQT0D15umSGC9lSzL9w19JlarnKKM3Qv0GQSjfUm HvIutePPHUTBfUKjmYfdM14dhaRpYpGQdxZVmjZRuOG2LFztFI1dFwh8443kdWdBWFfv srtqOL+hl0qdsb296VjKgzLG08t2jnBtipGxp4CIRCw0n5BkESAlolGWwjgoEwUkVbWK lpmA== X-Gm-Message-State: AOAM5300mswye0f9QPw00suFi1n20XSI7cE2sWpb8+b1VOg/1Uc9JUSZ noT/Orurg89unvluiJwKnM2SHwZZxWFIMw== X-Google-Smtp-Source: ABdhPJylA3muk5yAlLrF6ZcVpEMYtRnxGVKqGdGUGSYY+nWAMfaRgU5cUbiR3WYP/UOF26ki7J90ZQ== X-Received: by 2002:a17:90a:708a:: with SMTP id g10mr9621854pjk.108.1623830573897; Wed, 16 Jun 2021 01:02:53 -0700 (PDT) Received: from localhost ([203.206.29.204]) by smtp.gmail.com with ESMTPSA id v15sm1595449pgf.26.2021.06.16.01.02.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 16 Jun 2021 01:02:53 -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 v13 1/3] kasan: allow an architecture to disable inline instrumentation Date: Wed, 16 Jun 2021 18:02:42 +1000 Message-Id: <20210616080244.51236-2-dja@axtens.net> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210616080244.51236-1-dja@axtens.net> References: <20210616080244.51236-1-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