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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id AD9EEC43334 for ; Thu, 23 Jun 2022 17:03:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229699AbiFWRDg (ORCPT ); Thu, 23 Jun 2022 13:03:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54702 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233750AbiFWRDJ (ORCPT ); Thu, 23 Jun 2022 13:03:09 -0400 Received: from sin.source.kernel.org (sin.source.kernel.org [145.40.73.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 56CEA50E21; Thu, 23 Jun 2022 09:54:52 -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 sin.source.kernel.org (Postfix) with ESMTPS id 9DF74CE25D9; Thu, 23 Jun 2022 16:54:37 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A40DFC3411B; Thu, 23 Jun 2022 16:54:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1656003276; bh=5G3EuymzBY0k7yl/c+FK2RyonhToevpO+9J1tU5W7xs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=KZ1NAesd2HVhUeguWQyHQXrFAqkvIzAfmsQDQAuUPprM/d3L9jyTaEFJRh0szVZR/ vIh8XTLadDEhQgrfVzk5zFIX4Y5tvqx+tz7KfT6pbWNGYG/frv6jQFpvwsWol+e/A7 lHBf3QrldMEY3SF7RvmJumRt8o8FPcAxmooMVeG8= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Thomas Gleixner , Arnd Bergmann , Dinh Nguyen , "Jason A. Donenfeld" Subject: [PATCH 4.9 187/264] nios2: use fallback for random_get_entropy() instead of zero Date: Thu, 23 Jun 2022 18:43:00 +0200 Message-Id: <20220623164349.359558460@linuxfoundation.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220623164344.053938039@linuxfoundation.org> References: <20220623164344.053938039@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: "Jason A. Donenfeld" commit c04e72700f2293013dab40208e809369378f224c upstream. In the event that random_get_entropy() can't access a cycle counter or similar, falling back to returning 0 is really not the best we can do. Instead, at least calling random_get_entropy_fallback() would be preferable, because that always needs to return _something_, even falling back to jiffies eventually. It's not as though random_get_entropy_fallback() 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 Cc: Arnd Bergmann Acked-by: Dinh Nguyen Signed-off-by: Jason A. Donenfeld Signed-off-by: Greg Kroah-Hartman --- arch/nios2/include/asm/timex.h | 3 +++ 1 file changed, 3 insertions(+) --- a/arch/nios2/include/asm/timex.h +++ b/arch/nios2/include/asm/timex.h @@ -20,5 +20,8 @@ typedef unsigned long cycles_t; extern cycles_t get_cycles(void); +#define get_cycles get_cycles + +#define random_get_entropy() (((unsigned long)get_cycles()) ?: random_get_entropy_fallback()) #endif