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Mon, 30 Nov 2020 20:30:43 +0000 (UTC) IronPort-SDR: h/cqkjam0UecJMxSQLteezNSY6ttuxMJCLpFeu69vnuW9e3K/YKTt9RBhJT/u7rANX818k0FUS TdsC2R4wd1Qw== X-IronPort-AV: E=McAfee;i="6000,8403,9821"; a="169207908" X-IronPort-AV: E=Sophos;i="5.78,382,1599548400"; d="scan'208";a="169207908" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga005.jf.intel.com ([10.7.209.41]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 30 Nov 2020 12:30:42 -0800 IronPort-SDR: yLA9PNQjHBgTUN90l8qgEkxgXoJuvUXG27s/rwGWPeH2Arxi9GbWUONoWVSPYmAvV7tpspKqWC LQD5AD69mzKw== X-IronPort-AV: E=Sophos;i="5.78,382,1599548400"; d="scan'208";a="549251245" Received: from yyu32-mobl1.amr.corp.intel.com (HELO [10.212.122.22]) ([10.212.122.22]) by orsmga005-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 30 Nov 2020 12:30:39 -0800 Subject: Re: [PATCH v15 05/26] x86/cet/shstk: Add Kconfig option for user-mode Shadow Stack To: Nick Desaulniers Cc: Dave.Martin@arm.com, arnd@arndb.de, bp@alien8.de, bsingharora@gmail.com, corbet@lwn.net, dave.hansen@linux.intel.com, esyr@redhat.com, fweimer@redhat.com, gorcunov@gmail.com, hjl.tools@gmail.com, hpa@zytor.com, jannh@google.com, keescook@chromium.org, linux-api@vger.kernel.org, linux-arch@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, luto@kernel.org, mike.kravetz@oracle.com, mingo@redhat.com, nadav.amit@gmail.com, oleg@redhat.com, pavel@ucw.cz, pengfei.xu@intel.com, peterz@infradead.org, ravi.v.shankar@intel.com, rdunlap@infradead.org, tglx@linutronix.de, vedvyas.shanbhogue@intel.com, weijiang.yang@intel.com, x86@kernel.org, Sami Tolvanen , Will Deacon , Masahiro Yamada References: <20201110162211.9207-6-yu-cheng.yu@intel.com> <20201130195602.331842-1-ndesaulniers@google.com> From: "Yu, Yu-cheng" Message-ID: <746c920b-01e2-b299-b5a1-8a29a5a2052d@intel.com> Date: Mon, 30 Nov 2020 12:30:38 -0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:68.0) Gecko/20100101 Thunderbird/68.12.1 MIME-Version: 1.0 In-Reply-To: <20201130195602.331842-1-ndesaulniers@google.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 11/30/2020 11:56 AM, Nick Desaulniers wrote: > In response to https://lore.kernel.org/lkml/20201110162211.9207-6-yu-cheng.yu@intel.com/. > > Hi Yu-cheng, > This feature reminds me very much of > ARCH_SUPPORTS_SHADOW_CALL_STACK/CC_HAVE_SHADOW_CALL_STACK implemented in > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=5287569a790d2546a06db07e391bf84b8bd6cf51. > > Do you think it would be worthwhile to share the same config name between x86 > and aarch64? The CET series has ARCH_HAS_SHADOW_STACK. In response to Boris' earlier comment, I think this maybe eliminated. In case it is still needed, I think it is better to have different names (but I am open to changing it). > > (Though, it seems on x86 there will be a distinction between kernel mode and > user mode configs, if I understand correctly?) > Yes, on x86, kernel and user-mode can be enabled separately. Yu-cheng