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=-0.8 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, 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 53007C47253 for ; Thu, 30 Apr 2020 18:42:37 +0000 (UTC) Received: from ml01.01.org (ml01.01.org [198.145.21.10]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 210F424959 for ; Thu, 30 Apr 2020 18:42:37 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="SKIj3ofh" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 210F424959 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-nvdimm-bounces@lists.01.org Received: from ml01.vlan13.01.org (localhost [IPv6:::1]) by ml01.01.org (Postfix) with ESMTP id 9D874110BB09F; Thu, 30 Apr 2020 11:41:24 -0700 (PDT) Received-SPF: Pass (mailfrom) identity=mailfrom; client-ip=198.145.29.99; helo=mail.kernel.org; envelope-from=luto@kernel.org; receiver= Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id 7FBAF10053E01 for ; Thu, 30 Apr 2020 11:41:22 -0700 (PDT) Received: from mail-wr1-f54.google.com (mail-wr1-f54.google.com [209.85.221.54]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 173BD24954 for ; Thu, 30 Apr 2020 18:42:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588272154; bh=R81KA1exG6QyWEvvM1/QecUU8WMGFHG/k/cxKcdkfnc=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=SKIj3ofhpyqALEnbxq/Qwt9I+q8xqgFA+l6wnFR3a2eTeE5nVt5QfYHFAwjC/y+Ja s8uytIm5fXDttDTtpNCgxSD0+3yT34ulwtIpiC/VwDctbm4BV5uOySFOyHPHNganWE ftAE+TPkYBb4X9BD4lyjCgOpqW23VPFKogllHC+c= Received: by mail-wr1-f54.google.com with SMTP id d15so8344818wrx.3 for ; Thu, 30 Apr 2020 11:42:34 -0700 (PDT) X-Gm-Message-State: AGi0Pua5zfTfC08IfLjfIsowZiiAVaEiLv0dLhnKpVuPdzusb+05+fWM ds7y3ckkvZ5o6m8HrqP8DuuslKn9/hJLTdtafFXbLw== X-Google-Smtp-Source: APiQypJgn2E33Ju/7FojR2A+zMnprCF7LbVkAmb0PlfhPmDEYEV5k/ga1+sfxFBZugZk5p4MRnQtkD5+A+c7WwtOQ+E= X-Received: by 2002:a5d:42c8:: with SMTP id t8mr3902056wrr.70.1588272152368; Thu, 30 Apr 2020 11:42:32 -0700 (PDT) MIME-Version: 1.0 References: <158823509800.2094061.9683997333958344535.stgit@dwillia2-desk3.amr.corp.intel.com>

In-Reply-To: From: Andy Lutomirski Date: Thu, 30 Apr 2020 11:42:20 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v2 0/2] Replace and improve "mcsafe" with copy_safe() To: Linus Torvalds Message-ID-Hash: ADZEANTRAQ7BOKC2U4ZVKP2RPOIHY3EM X-Message-ID-Hash: ADZEANTRAQ7BOKC2U4ZVKP2RPOIHY3EM X-MailFrom: luto@kernel.org X-Mailman-Rule-Hits: nonmember-moderation X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation CC: Andy Lutomirski , Thomas Gleixner , Ingo Molnar , Tony Luck , Peter Zijlstra , Borislav Petkov , stable , the arch/x86 maintainers , "H. Peter Anvin" , Paul Mackerras , Benjamin Herrenschmidt , Erwin Tsaur , Michael Ellerman , Arnaldo Carvalho de Melo , linux-nvdimm , Linux Kernel Mailing List X-Mailman-Version: 3.1.1 Precedence: list List-Id: "Linux-nvdimm developer list." Archived-At: List-Archive: List-Help: List-Post: List-Subscribe: List-Unsubscribe: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit On Thu, Apr 30, 2020 at 10:17 AM Linus Torvalds wrote: > > On Thu, Apr 30, 2020 at 9:52 AM Andy Lutomirski wrote: > > > > If I'm going to copy from memory that might be bad but is at least a > > valid pointer, I want a function to do this. If I'm going to copy > > from memory that might be entirely bogus, that's a different > > operation. In other words, if I'm writing e.g. filesystem that is > > touching get_user_pages()'d persistent memory, I don't want to panic > > if the memory fails, but I do want at least a very loud warning if I > > follow a wild pointer. > > > > So I think that probe_kernel_copy() is not a valid replacement for > > memcpy_mcsafe(). > > Fair enough. > > That said, the part I do like about probe_kernel_read/write() is that > it does indicate which part we think is possibly the one that needs > more care. > > Sure, it _might_ be both sides, but honestly, that's likely the much > less common case. Kind of like "copy_{to,from}_user()" vs > "copy_in_user()". > > Yes, the "copy_in_user()" case exists, but it's the odd and unusual case. I suppose there could be a consistent naming like this: copy_from_user() copy_to_user() copy_from_unchecked_kernel_address() [what probe_kernel_read() is] copy_to_unchecked_kernel_address() [what probe_kernel_write() is] copy_from_fallible() [from a kernel address that can fail to a kernel address that can't fail] copy_to_fallible() [the opposite, but hopefully identical to memcpy() on x86] copy_from_fallible_to_user() copy_from_user_to_fallible() These names are fairly verbose and could probably be improved. _______________________________________________ Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org To unsubscribe send an email to linux-nvdimm-leave@lists.01.org