From patchwork Fri Mar 7 16:48:49 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vincent Mailhol via B4 Relay X-Patchwork-Id: 14006773 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 3F63AC28B24 for ; Fri, 7 Mar 2025 16:49:41 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 5305610EBED; Fri, 7 Mar 2025 16:49:40 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.b="Gd3jT/cz"; dkim-atps=neutral Received: from nyc.source.kernel.org (nyc.source.kernel.org [147.75.193.91]) by gabe.freedesktop.org (Postfix) with ESMTPS id 5582610EBEF; Fri, 7 Mar 2025 16:49:39 +0000 (UTC) Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by nyc.source.kernel.org (Postfix) with ESMTP id C947DA43EC3; Fri, 7 Mar 2025 16:44:07 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPS id F28F7C4CEE2; Fri, 7 Mar 2025 16:49:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1741366178; bh=54wka74Fp0zqh1u6XsUsJBRpPbsbeMMktieA0LvyD2U=; h=From:Date:Subject:References:In-Reply-To:To:Cc:Reply-To:From; b=Gd3jT/czaw4IDIbDQMULKTh0eKh6eT6G6106lulbyhp+4PaxuE0R8atwa0DIwtpLd dDZGNUw6TeKEOfiNJlffEwS/Og6BrphgzhEOg3gLDq9G1XYpJ9/7GmGMElvEQ6cc1/ reZUMvEjQGz4161di2lPS8vCSiQSMfXY9lEB4VsHbdgvDiwK701ue25qPiKDngPSqU h4zIer32/tGVxlpZ57OBJebyVmAbXEW1GuehLrSrOfzTh4yF1VZseir2w91TpTUAnf HLD45v+2ySdNPMJ5TbMb0LN8dFcNrvkKMrkAM3D1Pum8scLReyoJd2Jib8YYsYjPKU MmCdZxtq2SZOw== 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 E5B4CC28B26; Fri, 7 Mar 2025 16:49:37 +0000 (UTC) From: Vincent Mailhol via B4 Relay Date: Sat, 08 Mar 2025 01:48:49 +0900 Subject: [PATCH v6 2/7] bits: introduce fixed-type genmasks MIME-Version: 1.0 Message-Id: <20250308-fixed-type-genmasks-v6-2-f59315e73c29@wanadoo.fr> References: <20250308-fixed-type-genmasks-v6-0-f59315e73c29@wanadoo.fr> In-Reply-To: <20250308-fixed-type-genmasks-v6-0-f59315e73c29@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 , Dmitry Baryshkov , Andy Shevchenko , Jani Nikula , Vincent Mailhol X-Mailer: b4 0.14.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=6361; i=mailhol.vincent@wanadoo.fr; h=from:subject:message-id; bh=CzbCc4cvmsTpWxzZbN4iqzEc27KjdIucQoTUeKsPeQY=; b=owGbwMvMwCV2McXO4Xp97WbG02pJDOmnlXvuf3uqzH59+bwYl/Ot2S+n7pBbJrfAJLle7KbO7 5VMqt/tO0pZGMS4GGTFFFmWlXNyK3QUeocd+msJM4eVCWQIAxenAEzEk4nhf3RQ0eqcG/89G7yO lp/k+bFGPnD55DSml0kH59qI2C+UTGFkeDvFWqG2UeTwzMDu/gMcJqIGTpEzqmbdnWdZXC7yzp+ VEwA= 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: Yury Norov Add GENMASK_TYPE() which generalizes __GENMASK() to support different types, and implement fixed-types versions of GENMASK() based on it. The fixed-type version allows more strict checks to the min/max values accepted, which is useful for defining registers like implemented by i915 and xe drivers with their REG_GENMASK*() macros. The strict checks rely on shift-count-overflow compiler check to fail the build if a number outside of the range allowed is passed. Example: #define FOO_MASK GENMASK_U32(33, 4) will generate a warning like: include/linux/bits.h:51:27: error: right shift count >= width of type [-Werror=shift-count-overflow] 51 | type_max(t) >> (BITS_PER_TYPE(t) - 1 - (h))))) | ^~ Signed-off-by: Yury Norov Signed-off-by: Lucas De Marchi Acked-by: Jani Nikula Co-developed-by: Vincent Mailhol Signed-off-by: Vincent Mailhol --- Changelog: v5 -> v6: - No changes. v4 -> v5: - Rename GENMASK_t() to GENMASK_TYPE(). - Fix typo in patch description. - Use tab indentations instead of single space to separate the macro name from its body. - s/__GENMASK_U*()/GENMASK_U*()/g in the comment. - Add a tag to credit myself as Co-developer. Keep Yury as the main author. - Modify GENMASK_TYPE() to match the changes made to __GENMASK() in: https://github.com/norov/linux/commit/1e7933a575ed - Replace (t)~_ULL(0) with type_max(t). This is OK because GENMASK_TYPE() is not available in asm. - linux/const.h and asm/bitsperlong.h are not used anymore. Remove them. - Apply GENMASK_TYPE() to GENMASK_U128(). - Remove the unsigned int cast for the U8 and U16 variants. Cast to the target type instead. Do that cast directly in GENMASK_TYPE(). v3 -> v4: - The v3 is one year old. Meanwhile people started using __GENMASK() directly. So instead of generalizing __GENMASK() to support different types, add a new GENMASK_t(). - replace ~0ULL by ~_ULL(0). Otherwise, GENMASK_t() would fail in asm code. - Make GENMASK_U8() and GENMASK_U16() return an unsigned int. In v3, due to the integer promotion rules, these were returning a signed integer. By casting these to unsigned int, at least the signedness is kept. --- include/linux/bitops.h | 1 - include/linux/bits.h | 55 ++++++++++++++++++++++++++++++++------------------ 2 files changed, 35 insertions(+), 21 deletions(-) diff --git a/include/linux/bitops.h b/include/linux/bitops.h index c1cb53cf2f0f8662ed3e324578f74330e63f935d..9be2d50da09a417966b3d11c84092bb2f4cd0bef 100644 --- a/include/linux/bitops.h +++ b/include/linux/bitops.h @@ -8,7 +8,6 @@ #include -#define BITS_PER_TYPE(type) (sizeof(type) * BITS_PER_BYTE) #define BITS_TO_LONGS(nr) __KERNEL_DIV_ROUND_UP(nr, BITS_PER_TYPE(long)) #define BITS_TO_U64(nr) __KERNEL_DIV_ROUND_UP(nr, BITS_PER_TYPE(u64)) #define BITS_TO_U32(nr) __KERNEL_DIV_ROUND_UP(nr, BITS_PER_TYPE(u32)) diff --git a/include/linux/bits.h b/include/linux/bits.h index 9c1c7ce0bba6bb09490d891904c143a5394fd512..b690611c769be61ab2b5ced43c8302ba5693308b 100644 --- a/include/linux/bits.h +++ b/include/linux/bits.h @@ -2,16 +2,15 @@ #ifndef __LINUX_BITS_H #define __LINUX_BITS_H -#include #include #include -#include #define BIT_MASK(nr) (UL(1) << ((nr) % BITS_PER_LONG)) #define BIT_WORD(nr) ((nr) / BITS_PER_LONG) #define BIT_ULL_MASK(nr) (ULL(1) << ((nr) % BITS_PER_LONG_LONG)) #define BIT_ULL_WORD(nr) ((nr) / BITS_PER_LONG_LONG) #define BITS_PER_BYTE 8 +#define BITS_PER_TYPE(type) (sizeof(type) * BITS_PER_BYTE) /* * Create a contiguous bitmask starting at bit position @l and ending at @@ -20,28 +19,44 @@ */ #if !defined(__ASSEMBLY__) -#include -#include - -#define GENMASK_INPUT_CHECK(h, l) BUILD_BUG_ON_ZERO(const_true((l) > (h))) - -#define GENMASK(h, l) \ - (GENMASK_INPUT_CHECK(h, l) + __GENMASK(h, l)) -#define GENMASK_ULL(h, l) \ - (GENMASK_INPUT_CHECK(h, l) + __GENMASK_ULL(h, l)) - /* * Missing asm support * - * __GENMASK_U128() depends on _BIT128() which would not work - * in the asm code, as it shifts an 'unsigned __int128' data - * type instead of direct representation of 128 bit constants - * such as long and unsigned long. The fundamental problem is - * that a 128 bit constant will get silently truncated by the - * gcc compiler. + * GENMASK_U*() depends on BITS_PER_TYPE() which relies on sizeof(), + * something not available in asm. Nethertheless, fixed width integers + * is a C concept. Assembly code can rely on the long and long long + * versions instead. */ -#define GENMASK_U128(h, l) \ - (GENMASK_INPUT_CHECK(h, l) + __GENMASK_U128(h, l)) + +#include +#include +#include + +#define GENMASK_INPUT_CHECK(h, l) BUILD_BUG_ON_ZERO(const_true((l) > (h))) + +/* + * Generate a mask for the specified type @t. Additional checks are made to + * guarantee the value returned fits in that type, relying on + * shift-count-overflow compiler check to detect incompatible arguments. + * For example, all these create build errors or warnings: + * + * - GENMASK(15, 20): wrong argument order + * - GENMASK(72, 15): doesn't fit unsigned long + * - GENMASK_U32(33, 15): doesn't fit in a u32 + */ +#define GENMASK_TYPE(t, h, l) \ + ((t)(GENMASK_INPUT_CHECK(h, l) + \ + (type_max(t) << (l) & \ + type_max(t) >> (BITS_PER_TYPE(t) - 1 - (h))))) + +#define GENMASK(h, l) GENMASK_TYPE(unsigned long, h, l) +#define GENMASK_ULL(h, l) GENMASK_TYPE(unsigned long long, h, l) + +#define GENMASK_U8(h, l) GENMASK_TYPE(u8, h, l) +#define GENMASK_U16(h, l) GENMASK_TYPE(u16, h, l) +#define GENMASK_U32(h, l) GENMASK_TYPE(u32, h, l) +#define GENMASK_U64(h, l) GENMASK_TYPE(u64, h, l) +#define GENMASK_U128(h, l) GENMASK_TYPE(u128, h, l) #else /* defined(__ASSEMBLY__) */