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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=no 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 B838BC43463 for ; Sun, 20 Sep 2020 16:00:25 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 3CEE920EDD for ; Sun, 20 Sep 2020 16:00:24 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3CEE920EDD Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arndb.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 474726B0073; Sun, 20 Sep 2020 12:00:24 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 3FB8C6B0070; 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Sun, 20 Sep 2020 16:00:22 +0000 (UTC) Received: from mail-qk1-f180.google.com ([209.85.222.180]) by mrelayeu.kundenserver.de (mreue011 [212.227.15.129]) with ESMTPSA (Nemesis) id 1N6Kl7-1kZA2W0E7F-016dnZ; Sun, 20 Sep 2020 18:00:21 +0200 Received: by mail-qk1-f180.google.com with SMTP id t138so12465279qka.0; Sun, 20 Sep 2020 09:00:20 -0700 (PDT) X-Gm-Message-State: AOAM533P3zL+lgOLkrE3LCmEmhwoz7YyWA35nIQ6Ij+STU4XpkivfZTI Sigu5IGRW1SpdIfO1aVSQczUtFpk+9NFEBSJ/aQ= X-Google-Smtp-Source: ABdhPJxWyfvCzQQBAWL//h6npTn88fQ05xaOWJspiDrXO43nFmdBtx69etP6R9R9/pXauFf/MfRV57t9JJqYkZya4Ms= X-Received: by 2002:a37:5d8:: with SMTP id 207mr42809575qkf.352.1600617619461; Sun, 20 Sep 2020 09:00:19 -0700 (PDT) MIME-Version: 1.0 References: <20200918124533.3487701-1-hch@lst.de> <20200918124533.3487701-2-hch@lst.de> <20200920151510.GS32101@casper.infradead.org> In-Reply-To: <20200920151510.GS32101@casper.infradead.org> From: Arnd Bergmann Date: Sun, 20 Sep 2020 18:00:03 +0200 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH 1/9] kernel: add a PF_FORCE_COMPAT flag To: Matthew Wilcox Cc: Christoph Hellwig , Alexander Viro , Andrew Morton , Jens Axboe , David Howells , Linux ARM , "the arch/x86 maintainers" , "linux-kernel@vger.kernel.org" , "open list:BROADCOM NVRAM DRIVER" , Parisc List , linuxppc-dev , linux-s390 , sparclinux , linux-block , linux-scsi , Linux FS-devel Mailing List , linux-aio , io-uring@vger.kernel.org, linux-arch , Linux-MM , Networking , keyrings@vger.kernel.org, LSM List Content-Type: text/plain; charset="UTF-8" X-Provags-ID: V03:K1:HhGeYamNhZfmW3n4qBsF6W4Lnl0ClRadqn+YnpEon6h74w8aJKq Rf0RAecd3fzFCb1jbuQdpbId10SM4yXjVgrt3ZwT0zhOffc6bEWIV3UjLD6KQD7J7mJ1YTe eFRY9QqBk7BEDLb8a2E0nTjWBQWVO6J7LQC2CitDzuHWZcdxH2BiUnLLzZbHHZ8u4sK+rAW /0MLCwn1rbqzxmBvEiCsQ== X-UI-Out-Filterresults: notjunk:1;V03:K0:joAiDsxsoZE=:ih2QFVWtfk+ow+nod+kyQl k4znsVU8naEna20BIJuvZW1NNidxGGMA8P5V+37FtoeVwfys0kZLVf1DEZ44wB4KjvM16JyKs yqjg55quCwQhcK2AaxAYtg/wz0MR/0w0Qg5dfcb9Iv5c6VZhp0z4dC8vzcYtz1ghtgNDWzixC sierrEvSL5FYW9Eitw2RnTW3Qd9afpehutOxHIt5FOWfShmb0vvNmUhxO0906unIroAIkggeu GsIuXMHmqWy5BkgBztOcq7pVboXMKgfVxNeK2PJamzx5mejefomxgj7G2oa34JbWXvL8dlqS5 VUT4Nu7JVcCS+A2G0vEh/Nkbd9Ta5A1h15jL6K4BF5PoUHNUyCpH+RCNz7S3EELNEioAlhOOT D0uJCii04vCH5ZJj6pUGoPVwaDHIK0QZnGGEhhJaE+/68rmxKAMgOjABfAnXs+me+o/uqktFz X9FmtBfpnWz4GQvdaVjnqwQNvsG2fqKTesPKWdsDA1mj32x2MET5jk5mA5LQfWn8XCPZhsWiF rLKkqWzZZVKhqmdVjS4O4bAuszuUe4EXskeASQ/jCJs1fAkYxohmO2zXIk4VHjw3uaVdjJeof zxoFyeRZKoWlbZvRvemaCWSxYNJJIOeoa6LwvfO2avX6mtTKt0fvQQFQActL88ZyQRU4ZfmXA Qf29M1E6+sqXmi0yp+pFeuZ80YkoO2ioNzRBRnBRJrIu4X0YgHIHdlz76XNNu1u3moeccvmab WKe7qIUL1dmxs3VowLXRPPn1kBEqVgARgyrTuMWulOq2C0L7FTrVH+Ge0ANZs8R6Yjcc+itic YF3QroZMW+5eaEx5ooA26xaSHGpcDudiNHx/IR1AXOpl2Fi0+EiDHK0i8+NkbqiwoLyrgSq 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 Sun, Sep 20, 2020 at 5:15 PM Matthew Wilcox wrote: > > On Fri, Sep 18, 2020 at 02:45:25PM +0200, Christoph Hellwig wrote: > > Add a flag to force processing a syscall as a compat syscall. This is > > required so that in_compat_syscall() works for I/O submitted by io_uring > > helper threads on behalf of compat syscalls. > > Al doesn't like this much, but my suggestion is to introduce two new > opcodes -- IORING_OP_READV32 and IORING_OP_WRITEV32. The compat code > can translate IORING_OP_READV to IORING_OP_READV32 and then the core > code can know what that user pointer is pointing to. How is that different from the current approach of storing the ABI as a flag in ctx->compat? Arnd