From patchwork Fri Jun 17 14:40:31 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Lobakin X-Patchwork-Id: 12885740 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 152D2CCA47E for ; Fri, 17 Jun 2022 14:41:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1382818AbiFQOlE (ORCPT ); Fri, 17 Jun 2022 10:41:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44312 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1382355AbiFQOk7 (ORCPT ); Fri, 17 Jun 2022 10:40:59 -0400 Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 36AEB52503; Fri, 17 Jun 2022 07:40:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1655476855; x=1687012855; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=THeq/t7OeFGS7kF1qxlxBPZVHuRcSkjtN1FGjFL0hbM=; b=WiB2oJ65/7rC7dKmiifE/o5i4GQSJvwbBbKJWyw63DekzX0cSPtYA1um BtS5NwkP0JEnPh+MqOH4qyq3/K6RPkWQYwodgPATdRdTl/0QrEeEMnDNv 6c0wKm8f1rixz6eqLujFLBoXEPmMyh/+gQqbP44aNbBgbT50nXVQzgAmT P3gj514DMqVc6wDvQyTkkjiQfLpi8vLY+yvoRndyzxIthb3IphXlqeNqq AbqlfsQdbspNcn41oPrV+AK8WlvlSxnC0ZwMmIo4guHXfxHEKh6qBwVtN SzzqJWLx1Iile7Lttt85XIWlI+/ydRNBp0ATJ45Z26kB4F/fCQ/5BikUK g==; X-IronPort-AV: E=McAfee;i="6400,9594,10380"; a="280246910" X-IronPort-AV: E=Sophos;i="5.92,306,1650956400"; d="scan'208";a="280246910" Received: from orsmga005.jf.intel.com ([10.7.209.41]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Jun 2022 07:40:54 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.92,306,1650956400"; d="scan'208";a="763274890" Received: from irvmail001.ir.intel.com ([10.43.11.63]) by orsmga005.jf.intel.com with ESMTP; 17 Jun 2022 07:40:49 -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 25HEeXl9024161; Fri, 17 Jun 2022 15:40:47 +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 v3 7/7] lib: test_bitmap: add compile-time optimization/evaluations assertions Date: Fri, 17 Jun 2022 16:40:31 +0200 Message-Id: <20220617144031.2549432-8-alexandr.lobakin@intel.com> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220617144031.2549432-1-alexandr.lobakin@intel.com> References: <20220617144031.2549432-1-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);