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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 9ECF8C43215 for ; Sat, 16 Nov 2019 11:25:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 81AF920729 for ; Sat, 16 Nov 2019 11:25:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727540AbfKPLZg (ORCPT ); Sat, 16 Nov 2019 06:25:36 -0500 Received: from Galois.linutronix.de ([193.142.43.55]:45185 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726794AbfKPLZg (ORCPT ); Sat, 16 Nov 2019 06:25:36 -0500 Received: from p5b06da22.dip0.t-ipconnect.de ([91.6.218.34] helo=nanos) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1iVwCh-0001hJ-05; Sat, 16 Nov 2019 12:25:23 +0100 Date: Sat, 16 Nov 2019 12:25:21 +0100 (CET) From: Thomas Gleixner To: =?UTF-8?Q?Stephan_M=C3=BCller?= cc: Arnd Bergmann , Greg Kroah-Hartman , linux-crypto@vger.kernel.org, LKML , linux-api@vger.kernel.org, "Eric W. Biederman" , "Alexander E. Patrakov" , "Ahmed S. Darwish" , "Theodore Y. Ts'o" , Willy Tarreau , Matthew Garrett , Vito Caputo , Andreas Dilger , Jan Kara , Ray Strode , William Jon McCann , zhangjs , Andy Lutomirski , Florian Weimer , Lennart Poettering , Nicolai Stange , "Peter, Matthias" , Marcelo Henrique Cerri , Roman Drahtmueller , Neil Horman Subject: Re: [PATCH v25 01/12] Linux Random Number Generator In-Reply-To: <2645285.kI0haNqfm4@positron.chronox.de> Message-ID: References: <6157374.ptSnyUpaCn@positron.chronox.de> <2787174.DQlWHN5GGo@positron.chronox.de> <2645285.kI0haNqfm4@positron.chronox.de> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="8323329-279224958-1573903523=:14348" X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. --8323329-279224958-1573903523=:14348 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT On Sat, 16 Nov 2019, Stephan Müller wrote: > +/** > + * Hot code path - Callback for interrupt handler > + */ > +void add_interrupt_randomness(int irq, int irq_flags) > +{ > + lrng_time_process(); > + > + if (!lrng_pool_highres_timer()) { > + struct pt_regs *regs = get_irq_regs(); > + static atomic_t reg_idx = ATOMIC_INIT(0); > + u64 ip; > + > + lrng_pool_lfsr_u32(jiffies); > + lrng_pool_lfsr_u32(irq); > + lrng_pool_lfsr_u32(irq_flags); > + > + if (regs) { > + u32 *ptr = (u32 *)regs; > + int reg_ptr = atomic_add_return_relaxed(1, ®_idx); > + size_t n = (sizeof(struct pt_regs) / sizeof(u32)); > + > + ip = instruction_pointer(regs); > + lrng_pool_lfsr_u32(*(ptr + (reg_ptr % n))); > + } else > + ip = _RET_IP_; > + > + lrng_pool_lfsr_u32(ip >> 32); > + lrng_pool_lfsr_u32(ip); > + } Is there a way to avoid all that processing right in the interrupt hot path and just store the raw data for later processing? Thanks, tglx --8323329-279224958-1573903523=:14348--