Message ID | 20220412172754.149498-6-Jason@zx2c4.com (mailing list archive) |
---|---|
State | New, archived |
Headers | show
Return-Path: <linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org> 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 B3F0CC433EF for <linux-riscv@archiver.kernel.org>; Tue, 12 Apr 2022 17:37:55 +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=snCI4DypitYXZjmZ7lIjzCxLezKaVpoww8KPCfSk6VY=; b=bhGCUHbPab2rsG 8a+/JkwMP6TmfaWFve2paIPCgf5hfvs6H5ICrn/8PQHXFcTb4K4+3t9ih3oRVHX2RwAKHgrM45ZYn tnugCU0jdm0EXIJMvr9NfCjIdZwLE2MGGdCna3C08EhW7Im+E+uY/P+ohTkhqos3WA8XavMKz4Cwm 65t94Ev0gaE3ik547mw6ZMFDhLHoeLaR9fkGI6wcW3YVsp95SkyymiUQUfBWkQDYmptpLnVxsxF83 wPrQwfgBhCUaCvVLksRZzENzsxNOO4uRJcwWuw0BiYTsmtx6gM80ck/T8iQ6CrF2BnAgUahVbDH/8 SfKWVkT2KTIDAHWQ6vnw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1neKSY-00FI15-Iw; Tue, 12 Apr 2022 17:37:46 +0000 Received: from sin.source.kernel.org ([2604:1380:40e1:4800::1]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1neKL3-00FE0F-Lh; Tue, 12 Apr 2022 17:30:03 +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 sin.source.kernel.org (Postfix) with ESMTPS id 5484ECE1FDB; Tue, 12 Apr 2022 17:29:59 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8F87EC385A1; Tue, 12 Apr 2022 17:29:54 +0000 (UTC) Authentication-Results: smtp.kernel.org; dkim=pass (1024-bit key) header.d=zx2c4.com header.i=@zx2c4.com header.b="IGqH+Yt+" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zx2c4.com; s=20210105; t=1649784593; 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=cpbrBqankh2fsmUUGS4FsleJ1lhokYXdTSW/sLYtQ34=; b=IGqH+Yt+TH/awWcML7+P4pTZAJ7vUKOoeTjgS80fkMNvRIanyEye8oWsTtwOEO/JteClTZ cNL6BWsiDaAhrLKgDy/7ihZyCJBRzKbJbE+/8XImGQoXwazt1CybSDia84OUDubwKS2Gt2 /vtAxFfC+bBVKO5EodD+RrfNWWRpG2I= Received: by mail.zx2c4.com (ZX2C4 Mail Server) with ESMTPSA id 5f9f93aa (TLSv1.3:AEAD-AES256-GCM-SHA384:256:NO); Tue, 12 Apr 2022 17:29:53 +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 v3 05/10] arm: use fallback for random_get_entropy() instead of zero Date: Tue, 12 Apr 2022 19:27:49 +0200 Message-Id: <20220412172754.149498-6-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_103002_135339_5630886E X-CRM114-Status: GOOD ( 14.35 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: <linux-riscv.lists.infradead.org> List-Unsubscribe: <http://lists.infradead.org/mailman/options/linux-riscv>, <mailto:linux-riscv-request@lists.infradead.org?subject=unsubscribe> List-Archive: <http://lists.infradead.org/pipermail/linux-riscv/> List-Post: <mailto:linux-riscv@lists.infradead.org> List-Help: <mailto:linux-riscv-request@lists.infradead.org?subject=help> List-Subscribe: <http://lists.infradead.org/mailman/listinfo/linux-riscv>, <mailto:linux-riscv-request@lists.infradead.org?subject=subscribe> Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" <linux-riscv-bounces@lists.infradead.org> Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org |
Series |
archs/random: fallback to best raw ktime when no cycle counter
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diff --git a/arch/arm/include/asm/timex.h b/arch/arm/include/asm/timex.h index 7c3b3671d6c2..6d1337c169cd 100644 --- a/arch/arm/include/asm/timex.h +++ b/arch/arm/include/asm/timex.h @@ -11,5 +11,6 @@ typedef unsigned long cycles_t; #define get_cycles() ({ cycles_t c; read_current_timer(&c) ? 0 : c; }) +#define random_get_entropy() (((unsigned long)get_cycles()) ?: random_get_entropy_fallback()) #endif
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 <tglx@linutronix.de> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Russell King <linux@armlinux.org.uk> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> --- arch/arm/include/asm/timex.h | 1 + 1 file changed, 1 insertion(+)