Message ID | 20220410214951.55294-3-Jason@zx2c4.com |
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State | New |
Headers | show
Return-Path: <SRS0=J2ug=UU=vger.kernel.org=sparclinux-owner@ozlabs.org> X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: bilbo.ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=zx2c4.com header.i=@zx2c4.com header.a=rsa-sha256 header.s=20210105 header.b=mljTD4lD; dkim-atps=neutral Received: from gandalf.ozlabs.org (gandalf.ozlabs.org [150.107.74.76]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (No client certificate requested) by bilbo.ozlabs.org (Postfix) with ESMTPS id 4Kc5Jl63gTz9sCD for <incoming@patchwork.ozlabs.org>; Mon, 11 Apr 2022 07:50:47 +1000 (AEST) Received: from gandalf.ozlabs.org (gandalf.ozlabs.org [150.107.74.76]) by gandalf.ozlabs.org (Postfix) with ESMTP id 4Kc5Jl5Zkkz4xNl for <incoming@patchwork.ozlabs.org>; Mon, 11 Apr 2022 07:50:47 +1000 (AEST) Received: by gandalf.ozlabs.org (Postfix) id 4Kc5Jl5Qbgz4xQq; Mon, 11 Apr 2022 07:50:47 +1000 (AEST) Delivered-To: patchwork-incoming@ozlabs.org Authentication-Results: gandalf.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=2620:137:e000::1:20; helo=out1.vger.email; envelope-from=sparclinux-owner@vger.kernel.org; receiver=<UNKNOWN>) Authentication-Results: gandalf.ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=zx2c4.com header.i=@zx2c4.com header.a=rsa-sha256 header.s=20210105 header.b=mljTD4lD; dkim-atps=neutral Received: from out1.vger.email (out1.vger.email [IPv6:2620:137:e000::1:20]) by gandalf.ozlabs.org (Postfix) with ESMTP id 4Kc5Jl5L8Jz4xNl for <patchwork-incoming@ozlabs.org>; Mon, 11 Apr 2022 07:50:47 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243996AbiDJVw4 (ORCPT <rfc822;patchwork-incoming@ozlabs.org>); Sun, 10 Apr 2022 17:52:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41242 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242933AbiDJVwx (ORCPT <rfc822;sparclinux@vger.kernel.org>); Sun, 10 Apr 2022 17:52:53 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 76A191A064; Sun, 10 Apr 2022 14:50:27 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 38289B80CD2; Sun, 10 Apr 2022 21:50:26 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id BA2B4C385A1; Sun, 10 Apr 2022 21:50:21 +0000 (UTC) Authentication-Results: smtp.kernel.org; dkim=pass (1024-bit key) header.d=zx2c4.com header.i=@zx2c4.com header.b="mljTD4lD" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zx2c4.com; s=20210105; t=1649627421; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=JyQJDqG7G7qoM6gKahWfWcpxoWg/Hr8hXOQQlij0UbM=; b=mljTD4lDHrPCpdKRHHsPWTFR14XiiWdhvN87TPRANPmZWfc+MO66VyuX/rXcSG22A4eyEP dnVOLtFaU6Sq0fucK3TI1wZEKw8xT1SKDR6YeAoPoyixF1BUW3rFAxNA+gC8iEtzcWxwSM 5HC0l2Iwg27gXOb6sTJlPKYcF+fyEVo= Received: by mail.zx2c4.com (ZX2C4 Mail Server) with ESMTPSA id 2f5fc337 (TLSv1.3:AEAD-AES256-GCM-SHA384:256:NO); Sun, 10 Apr 2022 21:50:20 +0000 (UTC) From: "Jason A. Donenfeld" <Jason@zx2c4.com> To: linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org, tglx@linutronix.de, arnd@arndb.de Cc: "Jason A. Donenfeld" <Jason@zx2c4.com>, Theodore Ts'o <tytso@mit.edu>, Dominik Brodowski <linux@dominikbrodowski.net>, Russell King <linux@armlinux.org.uk>, Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will@kernel.org>, Geert Uytterhoeven <geert@linux-m68k.org>, Thomas Bogendoerfer <tsbogend@alpha.franken.de>, Paul Walmsley <paul.walmsley@sifive.com>, Palmer Dabbelt <palmer@dabbelt.com>, Albert Ou <aou@eecs.berkeley.edu>, "David S . Miller" <davem@davemloft.net>, Richard Weinberger <richard@nod.at>, Anton Ivanov <anton.ivanov@cambridgegreys.com>, Johannes Berg <johannes@sipsolutions.net>, Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>, Dave Hansen <dave.hansen@linux.intel.com>, "H . Peter Anvin" <hpa@zytor.com>, Chris Zankel <chris@zankel.net>, Max Filippov <jcmvbkbc@gmail.com>, John Stultz <john.stultz@linaro.org>, Stephen Boyd <sboyd@kernel.org>, Dinh Nguyen <dinguyen@kernel.org>, linux-arm-kernel@lists.infradead.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, linux-riscv@lists.infradead.org, sparclinux@vger.kernel.org, linux-um@lists.infradead.org, x86@kernel.org, linux-xtensa@linux-xtensa.org Subject: [PATCH v2 02/11] timekeeping: use ktime_read_raw_clock() for random_get_entropy() if no get_cycles() Date: Sun, 10 Apr 2022 23:49:42 +0200 Message-Id: <20220410214951.55294-3-Jason@zx2c4.com> In-Reply-To: <20220410214951.55294-1-Jason@zx2c4.com> References: <20220410214951.55294-1-Jason@zx2c4.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-6.8 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, RCVD_IN_DNSWL_HI,SPF_HELO_NONE,SPF_PASS,T_SCC_BODY_TEXT_LINE autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: <sparclinux.vger.kernel.org> X-Mailing-List: sparclinux@vger.kernel.org |
Series |
archs/random: fallback to using ktime_read_raw_clock() if no cycle counter
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expand
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diff --git a/include/linux/timex.h b/include/linux/timex.h index 56502b338287..4050f68c34cb 100644 --- a/include/linux/timex.h +++ b/include/linux/timex.h @@ -76,8 +76,14 @@ extern u64 ktime_read_raw_clock(void); * * By default we use get_cycles() for this purpose, but individual * architectures may override this in their asm/timex.h header file. + * If a given arch does not have get_cycles(), then we fallback to + * using sched_clock(). */ +#ifdef get_cycles #define random_get_entropy() ((unsigned long)get_cycles()) +#else +#define random_get_entropy() ((unsigned long)ktime_read_raw_clock()) +#endif #endif /*
In the event that a given arch does not define get_cycles(), falling back to the get_cycles() default implementation that returns 0 is really not the best we can do. Instead, at least calling ktime_read_raw_clock() would be preferable, because that always needs to return _something_, even falling back to jiffies eventually. It's not as though ktime_read_raw_clock() is super high precision or guaranteed to be entropic, but basically anything that's not zero all the time is better than returning zero all the time. Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> --- include/linux/timex.h | 6 ++++++ 1 file changed, 6 insertions(+)