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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 9B237C433EF for ; Wed, 23 Feb 2022 09:07:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Content-Type: Content-Transfer-Encoding:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:From:References:Cc:To:Subject: MIME-Version:Date:Message-ID:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=SuBDmyctahO9lUL+GTKU+2ISMoiaoJSAO0yQ9UlQKls=; b=VEx6kz83EPqyJ3 iuCKeCI6166csmhDrDXWwBKH9xcV34pk/MCqiwuf3wPGJX4NueJw7NtDRf5pl322eC3ax9WHihD4S P0hfOvoV4Hk+V5beu416jllnZSeQHnSew/61PA0/UyQ6nh+12gKFg6u05XlosBq12hWhZ9IKDnC/1 o0tzRL4WkNJ6v0N860nhhzsXORL2Rch0ZsL2QYLWYlkjA0a+5UA4lrT5f8+QrC7CYSMg2DmMU7dvV cVQxFV+Ggu8obN4Z7jBTxuDxUa3O01jOQCp2fTv5F/MwVeDphEbd/pDH9+COzcmTkVdqqiYmOXf3A WR/i8ZvI2HdlRS5mRkDg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nMnbA-00DPlO-TA; Wed, 23 Feb 2022 09:06:13 +0000 Received: from out30-44.freemail.mail.aliyun.com ([115.124.30.44]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1nMnb5-00DPjC-36 for linux-arm-kernel@lists.infradead.org; Wed, 23 Feb 2022 09:06:10 +0000 X-Alimail-AntiSpam: AC=PASS; BC=-1|-1; BR=01201311R931e4; CH=green; DM=||false|; DS=||; FP=0|-1|-1|-1|0|-1|-1|-1; HT=e01e04407; MF=ashimida@linux.alibaba.com; NM=1; PH=DS; RN=20; SR=0; TI=SMTPD_---0V5I3avg_1645607161; Received: from 192.168.193.152(mailfrom:ashimida@linux.alibaba.com fp:SMTPD_---0V5I3avg_1645607161) by smtp.aliyun-inc.com(127.0.0.1); Wed, 23 Feb 2022 17:06:02 +0800 Message-ID: Date: Wed, 23 Feb 2022 01:06:01 -0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.6.0 Subject: Re: [PATCH] [PATCH] AARCH64: Add gcc Shadow Call Stack support Content-Language: en-US To: Mark Rutland Cc: catalin.marinas@arm.com, will@kernel.org, nathan@kernel.org, ndesaulniers@google.com, keescook@chromium.org, masahiroy@kernel.org, tglx@linutronix.de, akpm@linux-foundation.org, samitolvanen@google.com, npiggin@gmail.com, linux@roeck-us.net, mhiramat@kernel.org, ojeda@kernel.org, luc.vanoostenryck@gmail.com, elver@google.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, llvm@lists.linux.dev, linux-hardening@vger.kernel.org References: <20220222095736.24898-1-ashimida@linux.alibaba.com> From: Dan Li In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220223_010607_359745_0F4D801F X-CRM114-Status: GOOD ( 25.10 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 2/22/22 10:47, Mark Rutland wrote: > Hi, > > On Tue, Feb 22, 2022 at 01:57:36AM -0800, Dan Li wrote: >> Shadow call stack is available in GCC > 11.2.0, this patch makes >> the corresponding kernel configuration available when compiling >> the kernel with gcc. > > Neat! > > My local GCC devs told me that means GCC 12.x.x rather than 11.2.x or > 11.3.x, so as others have said it'd be clearer to say `GCC >= 12.0.0`. > Ah, yes, I just saw this flag in gcc/BASE-VER. > I'd like to try this with a GCC binary before I provide an Ack or R-b; > but in the mean time I have a few comments below. > Thanks for your test, Mark. Please let me know if there is any issues :) >> --- >> FYI: >> This function can be used to test if the shadow call stack works: >> //noinline void __noscs scs_test(void) >> noinline void scs_test(void) >> { >> register unsigned long *sp asm("sp"); >> unsigned long * lr = sp + 1; >> >> asm volatile("":::"x30"); >> *lr = 0; >> } > > It's probably be better to use __builtin_frame_address(0) to get the > address of the frame record rather than assuming that fp==sp in the > middle of the function. > Got it. >> config SHADOW_CALL_STACK >> - bool "Clang Shadow Call Stack" >> - depends on CC_IS_CLANG && ARCH_SUPPORTS_SHADOW_CALL_STACK >> + bool "Shadow Call Stack" >> + depends on ARCH_SUPPORTS_SHADOW_CALL_STACK >> depends on DYNAMIC_FTRACE_WITH_REGS || !FUNCTION_GRAPH_TRACER >> help >> - This option enables Clang's Shadow Call Stack, which uses a >> + This option enables Clang/GCC's Shadow Call Stack, which uses a >> shadow stack to protect function return addresses from being >> overwritten by an attacker. More information can be found in >> Clang's documentation: > > Is there any additional GCC documentation that we can refer to? > Currently there is only a brief description of -fsanitize=shadow-call-stack in the user manual. Since the description of the clang documentation is more detailed, should I add this gcc link to the configuration description? Link: https://gcc.gnu.org/onlinedocs/gcc/Instrumentation-Options.html#Instrumentation-Options >> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig >> index 09b885cc4db5..a48a604301aa 100644 >> --- a/arch/arm64/Kconfig >> +++ b/arch/arm64/Kconfig >> @@ -1255,7 +1255,7 @@ config HW_PERF_EVENTS >> config ARCH_HAS_FILTER_PGPROT >> def_bool y >> >> -# Supported by clang >= 7.0 >> +# Supported by clang >= 7.0 or GCC > 11.2.0 > > As above, I beleive that should be `GCC >= 12.0.0`. > Yeah. Thanks, Dan. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel