From patchwork Tue Jun 21 19:15:53 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Lobakin X-Patchwork-Id: 12889617 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 18314C433EF for ; Tue, 21 Jun 2022 19:17:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1353604AbiFUTRX (ORCPT ); Tue, 21 Jun 2022 15:17:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36782 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1353296AbiFUTRL (ORCPT ); Tue, 21 Jun 2022 15:17:11 -0400 Received: from mga12.intel.com (mga12.intel.com [192.55.52.136]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2DA6519034; Tue, 21 Jun 2022 12:16:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1655838987; x=1687374987; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=YBBT3g4AuHURoy+25BrMz0CCKzpPjscESAN6DotPoig=; b=HoSjBoDXhwJZc5j7XlOvqwXLc7aCn7aa17aI57+itYRgj6C2ud2vNx1L AWb8gPzNcZ4ncOrQQj9c+YflhppzK64Eo6vvLwGWki2jqpqr8bvVlnG37 WwULNkqZ5Vi5ASZ7r3Iywqyd6xwpvZtPm53yAJQufqZeHWxkB4YVMHEGL Gf3VcM4gxKA9CyvxP4AVX39Yjqv+AOBzBEf52ZwWdvH2Uli0BR1kqaGH/ R/Oa5gM3a3VrLzr65tpGQ4ERjZLNSg9L4b0my+2C8DVLYqnMeownK/LSh Lrw9cPV3D6dOHPMa05fxNPSSd2PcbjRNMmkttKZtqS4j+U8bHFag7JJBV g==; X-IronPort-AV: E=McAfee;i="6400,9594,10385"; a="260035058" X-IronPort-AV: E=Sophos;i="5.92,210,1650956400"; d="scan'208";a="260035058" Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Jun 2022 12:16:27 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.92,210,1650956400"; d="scan'208";a="677150415" Received: from irvmail001.ir.intel.com ([10.43.11.63]) by FMSMGA003.fm.intel.com with ESMTP; 21 Jun 2022 12:16:21 -0700 Received: from newjersey.igk.intel.com (newjersey.igk.intel.com [10.102.20.203]) by irvmail001.ir.intel.com (8.14.3/8.13.6/MailSET/Hub) with ESMTP id 25LJG7oH012650; Tue, 21 Jun 2022 20:16:19 +0100 From: Alexander Lobakin To: Arnd Bergmann , Yury Norov Cc: Alexander Lobakin , Andy Shevchenko , Mark Rutland , Matt Turner , Brian Cain , Geert Uytterhoeven , Yoshinori Sato , Rich Felker , "David S. Miller" , Kees Cook , "Peter Zijlstra (Intel)" , Marco Elver , Borislav Petkov , Tony Luck , Maciej Fijalkowski , Jesse Brandeburg , Greg Kroah-Hartman , linux-alpha@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v4 8/8] lib: test_bitmap: add compile-time optimization/evaluations assertions Date: Tue, 21 Jun 2022 21:15:53 +0200 Message-Id: <20220621191553.69455-9-alexandr.lobakin@intel.com> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220621191553.69455-1-alexandr.lobakin@intel.com> References: <20220621191553.69455-1-alexandr.lobakin@intel.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-sh@vger.kernel.org Add a function to the bitmap test suite, which will ensure that compilers are able to evaluate operations performed by the bitops/bitmap helpers to compile-time constants when all of the arguments are compile-time constants as well, or trigger a build bug otherwise. This should work on all architectures and all the optimization levels supported by Kbuild. The function doesn't perform any runtime tests and gets optimized out to nothing after passing the build assertions. Suggested-by: Yury Norov Signed-off-by: Alexander Lobakin Reviewed-by: Andy Shevchenko --- lib/test_bitmap.c | 45 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 45 insertions(+) diff --git a/lib/test_bitmap.c b/lib/test_bitmap.c index d5923a640457..3a7b09b82794 100644 --- a/lib/test_bitmap.c +++ b/lib/test_bitmap.c @@ -869,6 +869,50 @@ static void __init test_bitmap_print_buf(void) } } +static void __init test_bitmap_const_eval(void) +{ + DECLARE_BITMAP(bitmap, BITS_PER_LONG); + unsigned long initvar = BIT(2); + unsigned long bitopvar = 0; + unsigned long var = 0; + int res; + + /* + * Compilers must be able to optimize all of those to compile-time + * constants on any supported optimization level (-O2, -Os) and any + * architecture. Otherwise, trigger a build bug. + * The whole function gets optimized out then, there's nothing to do + * in runtime. + */ + + /* Equals to `unsigned long bitmap[1] = { BIT(5), }` */ + bitmap_clear(bitmap, 0, BITS_PER_LONG); + if (!test_bit(7, bitmap)) + bitmap_set(bitmap, 5, 1); + + /* Equals to `unsigned long bitopvar = BIT(20)` */ + __change_bit(31, &bitopvar); + bitmap_shift_right(&bitopvar, &bitopvar, 11, BITS_PER_LONG); + + /* Equals to `unsigned long var = BIT(25)` */ + var |= BIT(25); + if (var & BIT(0)) + var ^= GENMASK(9, 6); + + /* __const_hweight<32|64>(BIT(5)) == 1 */ + res = bitmap_weight(bitmap, 20); + BUILD_BUG_ON(!__builtin_constant_p(res)); + + /* !(BIT(31) & BIT(18)) == 1 */ + res = !test_bit(18, &bitopvar); + BUILD_BUG_ON(!__builtin_constant_p(res)); + + /* BIT(2) & GENMASK(14, 8) == 0 */ + BUILD_BUG_ON(!__builtin_constant_p(initvar & GENMASK(14, 8))); + /* ~BIT(25) */ + BUILD_BUG_ON(!__builtin_constant_p(~var)); +} + static void __init selftest(void) { test_zero_clear(); @@ -884,6 +928,7 @@ static void __init selftest(void) test_for_each_set_clump8(); test_bitmap_cut(); test_bitmap_print_buf(); + test_bitmap_const_eval(); } KSTM_MODULE_LOADERS(test_bitmap);