From patchwork Tue Dec 19 16:05:54 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Crt Mori X-Patchwork-Id: 10123677 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id B1877603B5 for ; Tue, 19 Dec 2017 16:06:20 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 9F43428CFB for ; Tue, 19 Dec 2017 16:06:20 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 9336B28ECC; Tue, 19 Dec 2017 16:06:20 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=2.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_HI,T_DKIM_INVALID autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 0FF2A28CFB for ; Tue, 19 Dec 2017 16:06:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752215AbdLSQGG (ORCPT ); Tue, 19 Dec 2017 11:06:06 -0500 Received: from mail-wr0-f196.google.com ([209.85.128.196]:35633 "EHLO mail-wr0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752407AbdLSQGC (ORCPT ); Tue, 19 Dec 2017 11:06:02 -0500 Received: by mail-wr0-f196.google.com with SMTP id l19so7406050wrc.2 for ; Tue, 19 Dec 2017 08:06:02 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=melexis.com; s=google; h=from:to:cc:subject:date:message-id; bh=JktysdNOvxYJR80284XSJHp82NI90n3bYWW7voGw4GQ=; b=OTmnR+o0isFCh4MZZErYoaOdC+5/4sQvc4CC8p4SUAI7I1dhnESSH+5GmrL7fQte1K Ahu/6r/f4JXP4wbIQmTUOWjQqhrK6Z0PpkSrWSDROf/1xKlSGJ8miZCpUrmHST9zJLYM 9FK/Okn0e/FxrPLIvg/K+Bp0VYFg0RZXTBC4zVNxi3B6azGAhbqQJZaKMANmGwJHJMv4 JqgOvTvpZqbCAmLSElguomqAsPc96x7gjB/RFslBMVEDviNoDmuaz3Njg/jdOQ+K0Cyp Gu/Etw7UL3fgolVExQtdv5tIYr7I9lA0tRVTojnRc4qpiLrxO8x2yzOdwvJdrwEzdmZ8 JMPA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=JktysdNOvxYJR80284XSJHp82NI90n3bYWW7voGw4GQ=; b=qjkW5Itxz2Out5CwQC2yj9cHAwpJ5ejqbpvd9LWw48u6xx+FQCKv2QdzU23ikiOwyI 4qeyBfmijA5tWvb4vxiFBbPVIYgZQ98ZGccO+5/xa4DNwl+djYylhpoRGxxZTVrHZ6zV 1SHzIJscO7foWuvi4DtXtMYh7DNVVLV3jrp9KpCNUk1AVx8TGIDm/N2SwF4tqxULeWda f6SsYhxZercfWnS1BLBWHX3tki138h1HnaTjzuSCL0mleDMhaQ7CutEs9oxxhH5mzuHk qK13Aw8KPw1fI+Kp6EDDKSjBcdsjy2uZo5ZdXOLo7DYt++ZG44Z0EaPvmBK9cQoEis+y bK1w== X-Gm-Message-State: AKGB3mKgXAAZp5s7Nf4hxJx44Z4LyUhQ6I//AyfiDIilylHpUvacXl7z 90/mSf8pBGPhLc3xjKA4B+5M1A== X-Google-Smtp-Source: ACJfBovLYvyOFyAGZyTPcSEKmdJ4iHcZwukkkTzPADpkoPPVll5s0yikuIhhU7pf070vmcHLoutLBA== X-Received: by 10.223.153.233 with SMTP id y96mr5509077wrb.216.1513699561258; Tue, 19 Dec 2017 08:06:01 -0800 (PST) Received: from pc3729.tess.elex.be ([194.150.35.21]) by smtp.gmail.com with ESMTPSA id 20sm3797550wms.8.2017.12.19.08.05.59 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 19 Dec 2017 08:06:00 -0800 (PST) From: Crt Mori To: Jonathan Cameron Cc: Ingo Molnar , Andrew Morton , Kees Cook , Rusty Russell , Ian Abbott , Larry Finger , Niklas Soderlund , Thomas Gleixner , Krzysztof Kozlowski , Masahiro Yamada , linux-kernel@vger.kernel.org, linux-iio@vger.kernel.org, Peter Zijlstra , Joe Perches , Crt Mori Subject: [PATCH v8 1/3] lib: Add strongly typed 64bit int_sqrt Date: Tue, 19 Dec 2017 17:05:54 +0100 Message-Id: <20171219160554.30729-1-cmo@melexis.com> X-Mailer: git-send-email 2.15.0 Sender: linux-iio-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP There is no option to perform 64bit integer sqrt on 32bit platform. Added stronger typed int_sqrt64 enables the 64bit calculations to be performed on 32bit platforms. Although int_sqrt() is a rough approximation, the same algorithm is used in int_sqrt64() as good enough on 32bit platform. Signed-off-by: Crt Mori --- include/linux/kernel.h | 6 ++++++ lib/int_sqrt.c | 31 +++++++++++++++++++++++++++++++ 2 files changed, 37 insertions(+) diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 0ad4c3044cf9..f3bebd3a9213 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -459,6 +459,12 @@ extern int kernel_text_address(unsigned long addr); extern int func_ptr_is_kernel_text(void *ptr); unsigned long int_sqrt(unsigned long); +#if BITS_PER_LONG != 64 +#define int_sqrt64 _int_sqrt64 +u32 _int_sqrt64(u64 x); +#else +#define int_sqrt64 int_sqrt +#endif extern void bust_spinlocks(int yes); extern int oops_in_progress; /* If set, an oops, panic(), BUG() or die() is in progress */ diff --git a/lib/int_sqrt.c b/lib/int_sqrt.c index 1ef4cc344977..41338f1194b2 100644 --- a/lib/int_sqrt.c +++ b/lib/int_sqrt.c @@ -36,3 +36,34 @@ unsigned long int_sqrt(unsigned long x) return y; } EXPORT_SYMBOL(int_sqrt); + +#if BITS_PER_LONG != 64 +/** + * int_sqrt64 - strongly typed int_sqrt function when minimum 64 bit input + * is expected. + * @x: 64bit integer of which to calculate the sqrt + */ +u32 _int_sqrt64(u64 x) +{ + u64 b, m, y = 0; + + if (x <= 1) + return x; + + m = 1ULL << (64 - 2); + while (m != 0) { + b = y + m; + y >>= 1; + + if (x >= b) { + x -= b; + y += m; + } + m >>= 2; + } + + return y; +} +EXPORT_SYMBOL(_int_sqrt64); +#endif +