From patchwork Tue Mar 25 15:59:58 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vincent Mailhol X-Patchwork-Id: 14029186 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 gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (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 9AE5AC3600D for ; Tue, 25 Mar 2025 16:01:10 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 888FB10E5AE; Tue, 25 Mar 2025 16:00:58 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.b="YvFOw7/Q"; dkim-atps=neutral Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by gabe.freedesktop.org (Postfix) with ESMTPS id D564010E594; Tue, 25 Mar 2025 16:00:49 +0000 (UTC) Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id B423E43AE6; Tue, 25 Mar 2025 16:00:48 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPS id DD199C4CEEE; Tue, 25 Mar 2025 16:00:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1742918448; bh=y9tc24suY8ej5fpyVn/Hv/vLFuhuXdeRe9lG82YhJkg=; h=From:Date:Subject:References:In-Reply-To:To:Cc:Reply-To:From; b=YvFOw7/Q2U+o5QuFSBjaw+DMhICo8fG1RjeBHOksW0khM/+JY2HogQ7Jeu3Wf0OkW ZwxAeN/cFdCxnfNjQs3QG/duVId1uswCZ4o38fkKgoSnhwIdZMZbE+P12lcDIcyhuN SAX6DvlmJ7dX2eWwEr+2nemJ8T1U89cpwwjsy9gI0ud3ZqhUBnSuiLAuSoUJfc4Apc GC7bZ28ZDJkv0+wcVVOGJvGipNswOpLWmp41GKpR3GTiWVv2ZiG2EbmshKUwOxxGV1 RjO9BIeONU5BUk8ln4FGbPQntvh+bG8caRXQ04QB1UmkJj5IJmlmIetn/8Ej7ly8NR 7yHeJ2uOS52Lg== Received: from aws-us-west-2-korg-lkml-1.web.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.lore.kernel.org (Postfix) with ESMTP id D2106C3600E; Tue, 25 Mar 2025 16:00:48 +0000 (UTC) Date: Wed, 26 Mar 2025 00:59:58 +0900 Subject: [PATCH v8 3/6] bits: introduce fixed-type BIT_U*() MIME-Version: 1.0 Message-Id: <20250326-fixed-type-genmasks-v8-3-24afed16ca00@wanadoo.fr> References: <20250326-fixed-type-genmasks-v8-0-24afed16ca00@wanadoo.fr> In-Reply-To: <20250326-fixed-type-genmasks-v8-0-24afed16ca00@wanadoo.fr> To: Yury Norov , Lucas De Marchi , Rasmus Villemoes , Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , Tvrtko Ursulin , David Airlie , Simona Vetter , Andrew Morton Cc: linux-kernel@vger.kernel.org, intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, Andi Shyti , David Laight , Andy Shevchenko , Catalin Marinas , Anshuman Khandual , linux-arm-kernel@lists.infradead.org, Jani Nikula , Vincent Mailhol X-Mailer: b4 0.14.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=2997; i=mailhol.vincent@wanadoo.fr; h=from:subject:message-id; bh=ecrYrTAWwHY9wpOdzSBQxxCJ10uy07eNQ1Cgas05dhY=; b=owGbwMvMwCV2McXO4Xp97WbG02pJDOmPLqueeuV9oMJps6kYv6SP56NLnHb7ntzrPfSI5c9Fz sy14V92dJSyMIhxMciKKbIsK+fkVugo9A479NcSZg4rE8gQBi5OAZhIoxnDX1mf+86TFXl4/zW8 eu7uwO8eE6fJs1JSpizuQqjSrIOMLIwMP4qX2XZ+z+Jf/XKDjeMS3rMLEtbH/0somnBsnYN39nd tVgA= X-Developer-Key: i=mailhol.vincent@wanadoo.fr; a=openpgp; fpr=ED8F700574E67F20E574E8E2AB5FEB886DBB99C2 X-Endpoint-Received: by B4 Relay for mailhol.vincent@wanadoo.fr/default with auth_id=291 X-Original-From: Vincent Mailhol X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: mailhol.vincent@wanadoo.fr Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" From: Vincent Mailhol From: Lucas De Marchi Implement fixed-type BIT_U*() to help drivers add stricter checks, like it was done for GENMASK_U*(). Signed-off-by: Lucas De Marchi Acked-by: Jani Nikula Co-developed-by: Vincent Mailhol Signed-off-by: Vincent Mailhol Reviewed-by: Andy Shevchenko --- Changelog: v7 -> v8: - s/shift-count-overflow/-Wshift-count-overflow/g v6 -> v7: v5 -> v6: - No changes. v4 -> v5: - Rename GENMASK_t() to GENMASK_TYPE(). - Use tab indentations instead of single space to separate the macro name from its body. - Add a global comment at the beginning of the file to explain why GENMASK_U*() and BIT_U*() are not available in asm. - Add a new BIT_TYPE() helper function, similar to GENMASK_TYPE(). - Remove the unsigned int cast for the U8 and U16 variants. Move the cast to BIT_TYPE(). - Rename the argument from BIT_U*(b) to BIT_U*(nr) for consistency with vdso/bits.h. v3 -> v4: - Use const_true() to simplify BIT_INPUT_CHECK(). - Make BIT_U8() and BIT_U16() return an unsigned int instead of a u8 and u16. Because of the integer promotion rules in C, an u8 or an u16 would become a signed integer as soon as these are used in any expression. By casting these to unsigned ints, at least the signedness is kept. - Put the cast next to the BIT() macro. - In BIT_U64(): use BIT_ULL() instead of BIT(). --- include/linux/bits.h | 20 +++++++++++++++++++- 1 file changed, 19 insertions(+), 1 deletion(-) diff --git a/include/linux/bits.h b/include/linux/bits.h index 9718c5ae5fc356e66958cf48667bb1edda4f9673..7ad0562191153471dac729b0020cdb1c9d3049fc 100644 --- a/include/linux/bits.h +++ b/include/linux/bits.h @@ -24,7 +24,7 @@ /* * Missing asm support * - * GENMASK_U*() depend on BITS_PER_TYPE() which relies on sizeof(), + * GENMASK_U*() and BIT_U*() depend on BITS_PER_TYPE() which relies on sizeof(), * something not available in asm. Nevertheless, fixed width integers is a C * concept. Assembly code can rely on the long and long long versions instead. */ @@ -55,6 +55,24 @@ #define GENMASK_U32(h, l) GENMASK_TYPE(u32, h, l) #define GENMASK_U64(h, l) GENMASK_TYPE(u64, h, l) +/* + * Fixed-type variants of BIT(), with additional checks like GENMASK_TYPE(). The + * following examples generate compiler warnings due to -Wshift-count-overflow: + * + * - BIT_U8(8) + * - BIT_U32(-1) + * - BIT_U32(40) + */ +#define BIT_INPUT_CHECK(type, nr) \ + BUILD_BUG_ON_ZERO(const_true((nr) >= BITS_PER_TYPE(type))) + +#define BIT_TYPE(type, nr) ((type)(BIT_INPUT_CHECK(type, nr) + BIT_ULL(nr))) + +#define BIT_U8(nr) BIT_TYPE(u8, nr) +#define BIT_U16(nr) BIT_TYPE(u16, nr) +#define BIT_U32(nr) BIT_TYPE(u32, nr) +#define BIT_U64(nr) BIT_TYPE(u64, nr) + #else /* defined(__ASSEMBLY__) */ /*