From patchwork Tue Apr 12 17:27:52 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Jason A. Donenfeld" X-Patchwork-Id: 12811071 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 82C3FC433F5 for ; Tue, 12 Apr 2022 17:42:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=xuuLT3+N3IR/sEAbocjq3dkBjWbU+VzkNkC+Tk8ZV64=; b=kQcdUVn15Yn03Z s7F7wnFbrD9jXkoGnSAob/1SXfbOfaFGpSAwTnOAdBB7jb0w0FkEckjZ9H/OlxU6fRUN5ls9J2Tv6 KWikYAs60ndOVcUkNAVonW74WVCBfBNqd5LIvcc2e5S24RqFDbN9ZY1IHt/Cd25JER1jaMjBjClC8 IUi9KcY/YkAhQhNs/mtVBnR4e/uws1bU1MlNxb/i4GtleYwbI6C8cSRmUyQ82ISg1GEVcBc0N37J/ RpGo5Yn6zp9wUUp5FIZQgP2RYFQvoNuW8sTFgBOy8TeUVsuNL0RJy5zxckIxRew9HC398176oGydh fzmwwLhcj29AP6WdXRlQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1neKVY-00FJNt-N8; Tue, 12 Apr 2022 17:40:53 +0000 Received: from dfw.source.kernel.org ([139.178.84.217]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1neKLU-00FEEy-Tq; Tue, 12 Apr 2022 17:30:31 +0000 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 6CBB0619FD; Tue, 12 Apr 2022 17:30:28 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7E468C385A1; Tue, 12 Apr 2022 17:30:24 +0000 (UTC) Authentication-Results: smtp.kernel.org; dkim=pass (1024-bit key) header.d=zx2c4.com header.i=@zx2c4.com header.b="JwJo/PQY" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zx2c4.com; s=20210105; t=1649784624; 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=0AODITKYyJtEle+S4cX8w6pvyuCOHjrS7aFRmGybDo8=; b=JwJo/PQYB2t+UCyg5qqkA+832I4pAbKHeD0gzHYVsLb9l8HCvixAM0BPBsskZqHC5mtXRp akIYDLYMwf4Fr5xSALVMqVSAxYnk8vnRB66ck3Je/TfeBw48yQvVSWobxHKBsFkmZK0Kmk cvPAKwRBWBV2F/41mOwFnUqVmavoS1M= Received: by mail.zx2c4.com (ZX2C4 Mail Server) with ESMTPSA id b8a651ce (TLSv1.3:AEAD-AES256-GCM-SHA384:256:NO); Tue, 12 Apr 2022 17:30:23 +0000 (UTC) From: "Jason A. Donenfeld" To: linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org, tglx@linutronix.de, arnd@arndb.de Cc: "Jason A. Donenfeld" , Theodore Ts'o , Dominik Brodowski , Russell King , Catalin Marinas , Will Deacon , Geert Uytterhoeven , Thomas Bogendoerfer , Paul Walmsley , Palmer Dabbelt , Albert Ou , "David S . Miller" , Richard Weinberger , Anton Ivanov , Johannes Berg , Ingo Molnar , Borislav Petkov , Dave Hansen , "H . Peter Anvin" , Chris Zankel , Max Filippov , John Stultz , Stephen Boyd , Dinh Nguyen , 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 v3 08/10] um: use fallback for random_get_entropy() instead of zero Date: Tue, 12 Apr 2022 19:27:52 +0200 Message-Id: <20220412172754.149498-9-Jason@zx2c4.com> In-Reply-To: <20220412172754.149498-1-Jason@zx2c4.com> References: <20220412172754.149498-1-Jason@zx2c4.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220412_103029_163244_59776946 X-CRM114-Status: GOOD ( 16.11 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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. This is accomplished by just including the asm-generic code like on other architectures, which means we can get rid of the empty stub function here. Cc: Thomas Gleixner Cc: Arnd Bergmann Cc: Richard Weinberger Cc: Anton Ivanov Cc: Johannes Berg Signed-off-by: Jason A. Donenfeld --- arch/um/include/asm/timex.h | 9 ++------- 1 file changed, 2 insertions(+), 7 deletions(-) diff --git a/arch/um/include/asm/timex.h b/arch/um/include/asm/timex.h index e392a9a5bc9b..9f27176adb26 100644 --- a/arch/um/include/asm/timex.h +++ b/arch/um/include/asm/timex.h @@ -2,13 +2,8 @@ #ifndef __UM_TIMEX_H #define __UM_TIMEX_H -typedef unsigned long cycles_t; - -static inline cycles_t get_cycles (void) -{ - return 0; -} - #define CLOCK_TICK_RATE (HZ) +#include + #endif