From patchwork Sun Apr 10 21:49:41 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: 559506 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 79AEAC4332F for ; Sun, 10 Apr 2022 21:50:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242766AbiDJVwh (ORCPT ); Sun, 10 Apr 2022 17:52:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41064 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242793AbiDJVwe (ORCPT ); Sun, 10 Apr 2022 17:52:34 -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 EE5FC1706A; Sun, 10 Apr 2022 14:50:21 -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 A93AEB80E7B; Sun, 10 Apr 2022 21:50:20 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 31778C385AD; Sun, 10 Apr 2022 21:50:16 +0000 (UTC) Authentication-Results: smtp.kernel.org; dkim=pass (1024-bit key) header.d=zx2c4.com header.i=@zx2c4.com header.b="N/kh/3mi" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zx2c4.com; s=20210105; t=1649627415; 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=eCzcuPEAsFfV3KQBApenUVcgAqREPhA7I39P+jrbFEE=; b=N/kh/3milYkWfElQYLj5pol3Zh+yt3dFFaR1x4WN1G+GoRTaYgzUaCgs450uGUV/NmfpD7 fkbxjgPP/06fQeOc7+8NwwwXXk5PmfxvA+cloaTCbOIZrghQ2mom6zXVxWpLwE7PtdE9mv znqG4O0+VAQldUpD/4+kP4jcicb1oPk= Received: by mail.zx2c4.com (ZX2C4 Mail Server) with ESMTPSA id e822035e (TLSv1.3:AEAD-AES256-GCM-SHA384:256:NO); Sun, 10 Apr 2022 21:50:15 +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 v2 01/11] timekeeping: add accessor for raw clock Date: Sun, 10 Apr 2022 23:49:41 +0200 Message-Id: <20220410214951.55294-2-Jason@zx2c4.com> In-Reply-To: <20220410214951.55294-1-Jason@zx2c4.com> References: <20220410214951.55294-1-Jason@zx2c4.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org This provides access to whichever time source has the highest frequency, which is useful for gathering entropy on platforms without available cycle counters. It's not necessarily as good as being able to quickly access a cycle counter that the CPU has, but it's still something, even when it falls back to being jiffies-based. It's defined in linux/timex.h rather than linux/timekeeping.h, because the latter cannot be included easily from asm/ headers, and generally shouldn't be used outside of this rather narrow purpose. It's a ktime function, but it's not the usual ktime API. Suggested-by: Thomas Gleixner Cc: Arnd Bergmann Cc: Theodore Ts'o Signed-off-by: Jason A. Donenfeld --- include/linux/timex.h | 2 ++ kernel/time/timekeeping.c | 8 ++++++++ 2 files changed, 10 insertions(+) diff --git a/include/linux/timex.h b/include/linux/timex.h index 5745c90c8800..56502b338287 100644 --- a/include/linux/timex.h +++ b/include/linux/timex.h @@ -62,6 +62,8 @@ #include #include +extern u64 ktime_read_raw_clock(void); + #include #ifndef random_get_entropy diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index dcdcb85121e4..0d04d2e8b94b 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -939,6 +939,14 @@ ktime_t ktime_get_raw(void) } EXPORT_SYMBOL_GPL(ktime_get_raw); +/** + * ktime_read_raw_clock - Returns the raw clock source value + */ +u64 ktime_read_raw_clock(void) +{ + return tk_clock_read(&tk_core.timekeeper.tkr_mono); +} + /** * ktime_get_ts64 - get the monotonic clock in timespec64 format * @ts: pointer to timespec variable