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Thu, 15 Nov 2018 09:46:45 +0000 (UTC) Subject: Re: [PATCH] arm64: Make kpti command line options x86 compatible To: Christoph Hellwig Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, Catalin Marinas , Will Deacon , Richard Brown , Matthias Brugger References: <20181113152046.22389-1-agraf@suse.de> <20181115094116.GA18154@infradead.org> From: Alexander Graf Openpgp: preference=signencrypt Autocrypt: addr=agraf@suse.de; prefer-encrypt=mutual; keydata= xsFNBFJpUhABEADFUzxmkJeomCBLqm9Jtd6Iqp4B44JbEYoH3d+LegNJGV/CSnBTlH+es3yD v+y2Ke+AJsYqpAdry4dP8QpCe91+U/0IsI5V2WIyaKP39Zc/BYYGkhGXOgnE/4bIUL0Lomzx lxRaJ3uXZtU0QWgsFAtu6/Pq4cCJqdzB488MzwmvojMkNPwocwvAqhQkBxJQIbqV3wK9+oH8 O8NdWJmt/InNgEwWfgugIHATFSETmTlkIjUT0c1nhLLskVcYQiYFlk+SG/+P7aIQuR7jIaUv yA9VUfYAyh9WGwGwDL5zpZc2pz47bL3JhqdhDiEuglkDsGxCyk8YH6AntPlcWqKJ3rGlVfyT 8pvplU2aBhwKfWVk549MEe5ePLIuSNNuBqVDqIH3BiuRfYw0Sn6YL/klZCMvQIKDj3P5nviS ggtSLbv1bucxBiY9mKv0x/hHb7hwo9X4rO3kJaYox24oarZpOBshrqwjaA1z5cJeHsdzIhGx L8nxsbRFSk3Ci+sR0WtPf1/yJYtTmgQ1O5xllvBtVyNiifQ2bwgfONeY/4wqF5r9+hNOG/lR dbv1Z+/AmcAo/jt9Rt788H9iB6M5SE1pEp6UecY5OvG7XpUgGsjfJn6z22bINgD2HsLHAcuI 4ss79ZaPzP/0kASGk10roH9Y2MWSoLX4VdskN5keJYUtKe6xDwARAQABzR5BbGV4YW5kZXIg R3JhZiA8YWdyYWZAc3VzZS5kZT7CwXgEEwECACIFAlJpUj0CGy8GCwkIBwMCBhUIAgkKCwQW AgMBAh4BAheAAAoJEBYxMNpbJFMKHTIQAKDFXsBrDuiXqVVN0XPls0wDS/0hC4TEFIuuFWjo p5YL9mQzw8pRaxs9SD4YqelrVeTiOht66YjtSEuTVA/g/68ogPyFIIKrSXbIaoWKI8XT+I4W Fz5eKloxzpKns+5rM6QUSsK3LIVzWYShNO7/lp0GyAgiRTgj1OwC1mX8q9B4xB0aUYDlYmLf qDuoHicPNChgz60JCeZsG158zH0OUKIq0lOxg1v503izQKUzA+zFCFqA3AgRAgHnTyJHa3GZ 6o/uWjTTX0zqdkx8wCIC1g99nB+BzCr3McfchkS2ppVzh6hx4T0ng4JIOsOzIyQEAAwwH3Ph GHyvvF7LRC79Y/XBCXS1/CAgHRlTjeuih34Sf0kO0RmNpoqux2RYkn0R6b71gKDFxdY3512R lhfy8JcWWLFRJFP3AMhiSFxAxObLfRJM39D512cPUMqKluDh15YmqB076I//yw30SbpgLxV+ aS9iJkIEYaAbnPYvTLBKT/CL1Crj2nOCe60zQ9k0oz3dCFAwoklqSRbSxS8AAQBthaZY4tfj z2/pEjiVe/tvGnnaW5MN+meb/KOYXRFNCxRVvZ6Fy7ZuqmX+NC6ILN6DadFUYSMxZ/nznJcZ Js9Yd/KArW/qYtzkgxhYFF2xCIMyZkAepoR7nxeY9IT6oGiiuRk7PozFjcwRC0Rdy+AgzsFN BFJpUhABEADOTHgipY9H4CDOhcA9JnArlNcnDsXBaOOvv5ts0sdcRxBb8PNH35o7oEozNYTW GR8O1dzKDtn4zjIxY0tcRzrBB0dlQRRV7NYOLEGXTa6Bf55YR8Bv8ahh8mlNN2EiBn6WRREw krTuJet/o4vOwt22Hqts1KjMY9pOnV0kggl0NrNP/Tvhc6CNauo5ezz1PCrmO5Wgk1WB/E3G AnI4wtHyNHyRI/6deAM5u79GVO5teYTtf2ykpCR74C9oF5tqmLYsLdKz55IYwH/LRXkQQIqq nMOFvuhlYx3NZzu8vUZ16nxspDJYEgbVzny0J5/Ux9UkAi/K15CsNBAQbGnPgwo1WZzTTXQn 7FM+RyP3flqYBlNZ6NbroP/DRS9wKVC5ewe79wXEoQep7o95565ORDwSWMykQV99TvBTP45q vG11V2e02F36cORrIL3UZOM+HXYc4QAA/FHjnC/nng2lezYu/mZ1Aj/ePJmEOaygNYOij1WH A5xBelr9zR16BPExz/li6ghqTUbOtBJw7/5KwYNc7p1vQLHGW7FQaO0u8V4CUIjpJdc7ge1P yI5cTfCL5VfuQ12N8iUJbsmD6Z/ZLcYChPvlq001VI5hUCLzwxS8/qpHngLtWnMRNlJoHOO5 L8uOtMejd5aKY5hvYtEFrsQ4MHyQdqkva9aTDfxxqV5p1QARAQABwsN+BBgBAgAJBQJSaVIQ AhsuAikJEBYxMNpbJFMKwV0gBBkBAgAGBQJSaVIQAAoJECszeR4D/txgbOYP/0MxhLrpZOEl lMmAUu43DPVk3pWC6BxUaigtC3X8Bnmg2JsZ2MlWIks+l/TkTh2PrrkspGLzm1aw3kG2+sb5 w+dbtY8KLdaMbJKwd438VRQN729gi0zCOlAjdycmVEVYdgiMdUL4Qb9RR1uaPFha3/iW9WlR rVQWCi+gfsx49Mw8PPixraGt6yPBWhb66GUwqPfOshLJIYenPG3CkRlwCa/a2ECCjU2PeOGx W2BjWPgDx5aiJHhvNRo+7Le17uuGAobFcdkskK5VDqCvxbnKKjKGdgW9EOPRw6DJiOBt7Vrg H4H3RfKNG4y7WYbBuq3dW7qHdflku44SoG6ZTsRVfBZRFDioQf8QCilUhxwUbJjrQd/TgZiv kB+14u+YQy3sFnzQVU9FQWB1NzOOcd66nQrBcoEgG6s2GbbqC9XMDtPEhfG7ydezeh0BLYKl nLe/T25O1W///PVNvBRpQEU98eTT2Bv7/+zIGfcFkU6qXjc5Tx2hjEVvA8iJyosaI9/PGjCe lxLZBTuseMepFfKsyeLboCetFzx4fRikvVTtMyspc4JgVHlnwqXDE8PUZ4TPhJezsMDKiugu EcCdO0h7dfIeDVSDAx9rHvIpBI20i0RCrsBP+cbULQIPIzaJ95m5plJTIZPALa5NMeH3PuZl o+Dvzankq+Hj8ozqMPSbI5P7ZnwP/RanKlRztdcOt/GQdpACovKmMVChbZrp6z94yhYT25iG EusiAUwar9ViWnZVYxt8DaEojMkpSPXfFh2rFhTjrjWTlqmTTa5raYP3lBHzv4DlYoJtApo0 GiSyqd7QlXYQm3abFfI+6fnszg8dYz69GYVkwBpHLz0nA/u7XdMGYgeRiwHfWLVCxjxqoguw 0YSOnGFXfemuvAaVKfB0qY18F5j7SoUy72e5HnLpNg/zj3CBZFM40df8K+zqwtWfQicOM5IJ g1m5nhiB1rMWywSZ2pYkPHVjPJ68MkvCChsK5vSl4sIEoYkZnkQw5J+K8bwqaZZL0REK9xhH z+1FvVl7zEjCZXvyUm25ZS8iqAnlpk9UBFjXYKX8Ut9Y2iIDz3Pg3/FCLXbJSCQ6mIEe80Ns U2+L0x4LbU/JSxdN7+JC+1K36P66yBsWXk5347UdzPkvq6nlUqHPLpqpl4p+KzxI1TKK8co3 0gebQn/WLY3gqt6vCht2mdJztWPCL+r5kYodiYnpDXY/7SFr0+46QLRF1xG0J5UYGnz4koot 3173uxYy75CNZqYpqpLivEG6NXmGUNFypsbGuEhsAV2GWGyf0uT91XFE0SlRUxOMEHbLwwhP iMLccbHM2Kdf238nBUehU8iIsw/q6BWWw60MXH4Rw/1yya6JYvIyaG8ytoKhv8zZ Message-ID: <7af8ab89-6c55-3e54-e81c-4b5397cf0904@suse.de> Date: Thu, 15 Nov 2018 10:46:43 +0100 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:60.0) Gecko/20100101 Thunderbird/60.3.0 MIME-Version: 1.0 In-Reply-To: <20181115094116.GA18154@infradead.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 15.11.18 10:41, Christoph Hellwig wrote: > On Tue, Nov 13, 2018 at 04:20:46PM +0100, Alexander Graf wrote: >> I've already stumbled over 2 cases where people got confused about how to >> disable kpti on AArch64. In both cases, they used existing x86_64 options >> and just applied that to an AArch64 system, expecting it to work. >> >> I think it makes a lot of sense to have compatible kernel command line >> parameters whenever we can have them be compatible. >> >> So this patch adds the pti= and no_pti kernel command line options, mapping >> them into the existing kpti= command line framework. It preserves the old >> syntax to maintain compatibility with older command lines. >> >> While at it, the patch also marks the respective options as dual-arch. > > Thanks. Which also brings up my old complainst that arm64 and x86 should > use the same config option. Bonus points for moving the parsing code > to a common file.. Both archs handle the parameters in completely different code paths (probably due to arch constraints), so I'm not sure how doable it would be to combine the parsing. I'm also quite sure that we have more parameters like this around, especially with the other spectre mitigations. So if you see any, please feel free to send patches like this one to at least synchronize the user view. Alex