From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oo1-xc2f.google.com (mail-oo1-xc2f.google.com [IPv6:2607:f8b0:4864:20::c2f]) by sourceware.org (Postfix) with ESMTPS id E1A3F3858D1E for ; Wed, 13 Jul 2022 20:23:16 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org E1A3F3858D1E Received: by mail-oo1-xc2f.google.com with SMTP id v33-20020a4a9764000000b0035f814bb06eso2257650ooi.11 for ; Wed, 13 Jul 2022 13:23:16 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=dtudKzV1juvax2OSo5ROSeb5UFhedO352rhvj6cxLF0=; b=3HK3vJw8ZvIIxxeSG8qZAnrgXk6vIHGE/EioSkuvWrku/SCXQP/nRrly3Vo+O2nbkG 5IT4y+TxITYyoYHXOP0MNFlZjoEMavY6MEySZ4fTgKUtkg3S0WkMSTolzVcp98aHxWF9 caUG7xKgrgEzGz2xVxHRu5pEwN90D2HpyxQaoUp3PYiFVgMTEQ4rZWNLmjITxuW6lBRj WF0hHcAhQqMMk+aHFGHPV8IJB10h+06Q7GE2Z/rWc9mcK1aBAZ+GRI5yk+7hGXQVEbsv pCI7k/Mc3cOTIzu77E0fKT1XiBv4iCj1H5YxQO0Ph9e3EHTZ7RPAZPWY+JyAVLTb3Ohv H4ww== X-Gm-Message-State: AJIora9Df5s1CwoS71nfAd3s6Npj41HspSZ+C1rO+nqGJnYhQlKc/5D+ MHHtJugK9L6zHF404Y3m2yDG64mW8iMIHPBqd3g= X-Google-Smtp-Source: AGRyM1s6nUrzhC2CGGE4IVF6abkGwhCyEj00qqrasGptX/fA+ZV+YOxwd66lQDJCMHeIj1qdJb6NwkozOAnnqoTKXSM= X-Received: by 2002:a4a:c4c6:0:b0:435:48e0:b7ba with SMTP id g6-20020a4ac4c6000000b0043548e0b7bamr1889310ooq.12.1657743796273; Wed, 13 Jul 2022 13:23:16 -0700 (PDT) MIME-Version: 1.0 References: <20220713173657.516725-1-adhemerval.zanella@linaro.org> <20220713173657.516725-7-adhemerval.zanella@linaro.org> <87cze8zs3j.fsf@oldenburg.str.redhat.com> In-Reply-To: <87cze8zs3j.fsf@oldenburg.str.redhat.com> From: Noah Goldstein Date: Wed, 13 Jul 2022 13:23:04 -0700 Message-ID: Subject: Re: [PATCH v9 6/9] x86: Add AVX2 optimized chacha20 To: Florian Weimer Cc: Adhemerval Zanella , GNU C Library Content-Type: text/plain; charset="UTF-8" X-Spam-Status: No, score=-2.8 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, FREEMAIL_FROM, KAM_NUMSUBJECT, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP, T_SCC_BODY_TEXT_LINE autolearn=no autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 13 Jul 2022 20:23:18 -0000 On Wed, Jul 13, 2022 at 1:16 PM Florian Weimer wrote: > > * Noah Goldstein: > > > Since `arc4random ()` might need to read from /dev/urandom I don't > > think this function could ever truly be RTM safe so we may not care. > > > > If im missing something we do want to support RTM, should there be a > > '!CPU_FEATURE_USABLE_P (cpu_features, RTM)' check for the avx2 > > implementation? > > Calling arc4random from a transaction is potentially unsafe anyway > because it may act as an oracle that reveals the internal PRNG state. > The application needs to avoid that. I think we can use the AVX2 > implementation even with RTM enabled. Agreed. > > Thanks, > Florian >