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 D7E9BC43334 for ; Thu, 23 Jun 2022 18:09:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236051AbiFWSJr (ORCPT ); Thu, 23 Jun 2022 14:09:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47338 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236547AbiFWSIA (ORCPT ); Thu, 23 Jun 2022 14:08:00 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E600F87D62; Thu, 23 Jun 2022 10:19:31 -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 dfw.source.kernel.org (Postfix) with ESMTPS id 1104B61E6C; Thu, 23 Jun 2022 17:19:31 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B916BC341C4; Thu, 23 Jun 2022 17:19:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1656004770; bh=5G3EuymzBY0k7yl/c+FK2RyonhToevpO+9J1tU5W7xs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Kwag78v5oOaTMfMGkJdd0QrsnlX2ZZq/TAZfCiN03Kr3XDSupSCwBYvjBGiweUBo6 2uXO2DDq7zI79j0mM0skzFfQhhZ/Q5M3o3LK+kO4lTz/w/V/o/DRXE//nY6loZU4ub odOFj5y5cCRAzA63wS5QZrVrRpd2w0561rR4StYg= 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 4.19 144/234] nios2: use fallback for random_get_entropy() instead of zero Date: Thu, 23 Jun 2022 18:43:31 +0200 Message-Id: <20220623164347.130956265@linuxfoundation.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220623164343.042598055@linuxfoundation.org> References: <20220623164343.042598055@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: linux-kernel@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