From patchwork Mon Oct 23 10:23:26 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Potapenko X-Patchwork-Id: 156829 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a59:ce89:0:b0:403:3b70:6f57 with SMTP id p9csp1194649vqx; Mon, 23 Oct 2023 03:24:57 -0700 (PDT) X-Google-Smtp-Source: AGHT+IFsjFjVkeH3jD3zvBOINj94jAy5Y+Ku3kUSilzo5y0+niUZzCXLWi+H34fOMYL0pakgfnHW X-Received: by 2002:a17:902:b284:b0:1ca:3e40:beae with SMTP id u4-20020a170902b28400b001ca3e40beaemr7259311plr.38.1698056697611; Mon, 23 Oct 2023 03:24:57 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1698056697; cv=none; d=google.com; s=arc-20160816; b=jWNMrBh2K5b28P7syVc8QB3Q9yksbkqeUHdhDSljiIvnT9cd6iWSQYOpXCHm88q4zU 8Nr1c51pFfDxYloRPPk0mNgCEP//RdUWgcTrfWkXrP0N69ZG6QRP76mXuWUKUnr2KUdI jO8erveigTl3RTLOppcFGOlBPR6XfMPoLieNZHtwanEsCtL4v8MXg7deuSEWV8zcTMz9 dd5wkL5FEKdyY+VhaKWQGHADUdNlXVD35sB4u18dygouTLxvmIbPx9K5Z5/pYC60rDut B1ndrTtFMBAFQH8/KxhnB2N+wMpmkIXfFAg4L1hk99INJEEo+XZA6ErG196NslesNECq 7Ofg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:cc:to:from:subject:message-id:mime-version:date :dkim-signature; bh=3J/4PY2fr0LmELlkRa65xN9TiPDrp5/iGVWwAtVefeM=; fh=GmoqtqK5o+3hw8duGAYBcfcrbmWz8zn7GJB0HJXGJL0=; b=wOvms5VZ6juyVTdSLiYvXwdg9uPXra3G9DiZ4XIinbJ/bvbO65FeVR8Wleu5MrqNZ2 jMIFcMpYxuGfc6oefJP2xhCcpt7B3LC++abQlzAu8IusuCwTYqzud0Jl+s6zFJAXxXz+ SnyCuTtt09uAog+BvAuPKNyomq10rZ+YDoOZyKUYwDXHYSZ/35uZr/sWE0g9c16JZU+0 JUere9J1CKGSpPusXU5B+z3Mf/L9lQQVNx5K92mDZLVuqT7hCVws1esIlAgUt6fYEgkx /mytCGu1ts3IjA7X53bF9Fb3ay1R5wbTqz+1HZrb6mW5DIdVpzC4whHbCOGsC9qBQDvV 8k4A== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@google.com header.s=20230601 header.b=bna5BRZh; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:6 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: from pete.vger.email (pete.vger.email. [2620:137:e000::3:6]) by mx.google.com with ESMTPS id q9-20020a170902dac900b001c9ca0a03e8si6410792plx.68.2023.10.23.03.24.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 23 Oct 2023 03:24:57 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:6 as permitted sender) client-ip=2620:137:e000::3:6; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20230601 header.b=bna5BRZh; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:6 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: from out1.vger.email (depot.vger.email [IPv6:2620:137:e000::3:0]) by pete.vger.email (Postfix) with ESMTP id 485CB80A99A9; Mon, 23 Oct 2023 03:24:53 -0700 (PDT) X-Virus-Status: Clean X-Virus-Scanned: clamav-milter 0.103.10 at pete.vger.email Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229950AbjJWKYa (ORCPT + 27 others); Mon, 23 Oct 2023 06:24:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48000 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232874AbjJWKYP (ORCPT ); Mon, 23 Oct 2023 06:24:15 -0400 Received: from mail-yb1-xb49.google.com (mail-yb1-xb49.google.com [IPv6:2607:f8b0:4864:20::b49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 87EAF1704 for ; Mon, 23 Oct 2023 03:23:46 -0700 (PDT) Received: by mail-yb1-xb49.google.com with SMTP id 3f1490d57ef6-d9a581346c4so2911698276.0 for ; Mon, 23 Oct 2023 03:23:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1698056625; x=1698661425; darn=vger.kernel.org; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=3J/4PY2fr0LmELlkRa65xN9TiPDrp5/iGVWwAtVefeM=; b=bna5BRZhmPPHeiOgpB8Kk07Jk6m7cAckrKpOko2xvxXyEBfpsfTuVtDoAy5LQkZFqB n5JVamNj6yPA6KDOFAyZAm6H94shpyBkXFVXmfW2alXPClDIpFR5vp9+djbaqh7ugnfL B44dSN/igjjP4XH54ZuNKOAM5qWKGYS8YYWafVMNSZtwiERnZbE94xQQQYg+fDQ+47gL s0JEF3JLJxOHepWecKMxIo2F7ZiD8ntUXMbIiUiY/FVtWUOMSC55KkwWX1eA/jt/TERg ndJs9Z2esamFAAHQOVh9BV4dCp5DJn04Wrha0Jj+LSd6mhe10IN2j1B3yLNOIhXioflv tGzQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1698056625; x=1698661425; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=3J/4PY2fr0LmELlkRa65xN9TiPDrp5/iGVWwAtVefeM=; b=kjb9+KzZLa3EJ2SeIm/9rux+4wudRg+CmrDbp/VbU+DqyKCVNdrEd7SlmKlj2CGOr/ iQtgznz83lmjAsvPxLFYkd0EgksKf21fU5+tc+fevhs0fuiYQulCxQVG+4IdEoIZqeo2 YP22PqGyaR4kXXdaCBwS7CvTNd6XAEVGJvA+yWUsGctkWQvnI85lqakIGlx08WpH3RvV O663WRvARsjpQiHHVhptq/bFBx6GfiPq0vlJfle8SV/4C3OufKcmbbyP/2x9UDnDQttG eo2KMnzVJWIzfpTXN7SGnpMV65eonqqyCCzwDJKzuQ3Ttxh8yGsyzzjJq9fTCfC707Cx ScHg== X-Gm-Message-State: AOJu0YzmN4u7hcJXmsnU2Y7wD69ZVU1f4002elwn2QA8pmYzAeVqgC8J 7PpF419v80b67zSLaPRSyxkTfaTluoA= X-Received: from glider.muc.corp.google.com ([2a00:79e0:9c:201:348e:9a:326e:345e]) (user=glider job=sendgmr) by 2002:a25:d3d1:0:b0:d9a:6b0b:1bc8 with SMTP id e200-20020a25d3d1000000b00d9a6b0b1bc8mr168906ybf.11.1698056625436; Mon, 23 Oct 2023 03:23:45 -0700 (PDT) Date: Mon, 23 Oct 2023 12:23:26 +0200 Mime-Version: 1.0 X-Mailer: git-send-email 2.42.0.655.g421f12c284-goog Message-ID: <20231023102327.3074212-1-glider@google.com> Subject: [PATCH v8 1/2] lib/bitmap: add bitmap_{read,write}() From: Alexander Potapenko To: glider@google.com, catalin.marinas@arm.com, will@kernel.org, pcc@google.com, andreyknvl@gmail.com, andriy.shevchenko@linux.intel.com, aleksander.lobakin@intel.com, linux@rasmusvillemoes.dk, yury.norov@gmail.com, alexandru.elisei@arm.com Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, eugenis@google.com, syednwaris@gmail.com, william.gray@linaro.org, Arnd Bergmann X-Spam-Status: No, score=-8.4 required=5.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on pete.vger.email Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (pete.vger.email [0.0.0.0]); Mon, 23 Oct 2023 03:24:53 -0700 (PDT) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1780541499800185040 X-GMAIL-MSGID: 1780541499800185040 From: Syed Nayyar Waris The two new functions allow reading/writing values of length up to BITS_PER_LONG bits at arbitrary position in the bitmap. The code was taken from "bitops: Introduce the for_each_set_clump macro" by Syed Nayyar Waris with a number of changes and simplifications: - instead of using roundup(), which adds an unnecessary dependency on , we calculate space as BITS_PER_LONG-offset; - indentation is reduced by not using else-clauses (suggested by checkpatch for bitmap_get_value()); - bitmap_get_value()/bitmap_set_value() are renamed to bitmap_read() and bitmap_write(); - some redundant computations are omitted. Cc: Arnd Bergmann Signed-off-by: Syed Nayyar Waris Signed-off-by: William Breathitt Gray Link: https://lore.kernel.org/lkml/fe12eedf3666f4af5138de0e70b67a07c7f40338.1592224129.git.syednwaris@gmail.com/ Suggested-by: Yury Norov Co-developed-by: Alexander Potapenko Signed-off-by: Alexander Potapenko --- This patch was previously part of the "Implement MTE tag compression for swapped pages" series (https://lore.kernel.org/linux-arm-kernel/20231011172836.2579017-4-glider@google.com/T/) This patch was previously called "lib/bitmap: add bitmap_{set,get}_value()" (https://lore.kernel.org/lkml/20230720173956.3674987-2-glider@google.com/) v8: - as suggested by Andy Shevchenko, handle reads/writes of more than BITS_PER_LONG bits, add a note for 32-bit systems v7: - Address comments by Yury Norov, Andy Shevchenko, Rasmus Villemoes: - update code comments; - get rid of GENMASK(); - s/assign_bit/__assign_bit; - more vertical whitespace for better readability; - more compact code for bitmap_write() (now for real) v6: - As suggested by Yury Norov, do not require bitmap_read(..., 0) to return 0. v5: - Address comments by Yury Norov: - updated code comments and patch title/description - replace GENMASK(nbits - 1, 0) with BITMAP_LAST_WORD_MASK(nbits) - more compact bitmap_write() implementation v4: - Address comments by Andy Shevchenko and Yury Norov: - prevent passing values >= 64 to GENMASK() - fix commit authorship - change comments - check for unlikely(nbits==0) - drop unnecessary const declarations - fix kernel-doc comments - rename bitmap_{get,set}_value() to bitmap_{read,write}() --- include/linux/bitmap.h | 81 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 81 insertions(+) diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h index 03644237e1efb..d63d5e4b4ab54 100644 --- a/include/linux/bitmap.h +++ b/include/linux/bitmap.h @@ -77,6 +77,10 @@ struct device; * bitmap_to_arr64(buf, src, nbits) Copy nbits from buf to u64[] dst * bitmap_get_value8(map, start) Get 8bit value from map at start * bitmap_set_value8(map, value, start) Set 8bit value to map at start + * bitmap_read(map, start, nbits) Read an nbits-sized value from + * map at start + * bitmap_write(map, value, start, nbits) Write an nbits-sized value to + * map at start * * Note, bitmap_zero() and bitmap_fill() operate over the region of * unsigned longs, that is, bits behind bitmap till the unsigned long @@ -599,6 +603,83 @@ static inline void bitmap_set_value8(unsigned long *map, unsigned long value, map[index] |= value << offset; } +/** + * bitmap_read - read a value of n-bits from the memory region + * @map: address to the bitmap memory region + * @start: bit offset of the n-bit value + * @nbits: size of value in bits, nonzero, up to BITS_PER_LONG + * + * Returns: value of nbits located at the @start bit offset within the @map + * memory region. + * + * Note: callers on 32-bit systems must be careful to not attempt reading more + * than sizeof(unsigned long). + */ +static inline unsigned long bitmap_read(const unsigned long *map, + unsigned long start, + unsigned long nbits) +{ + size_t index = BIT_WORD(start); + unsigned long offset = start % BITS_PER_LONG; + unsigned long space = BITS_PER_LONG - offset; + unsigned long value_low, value_high; + + if (unlikely(!nbits || nbits > BITS_PER_LONG)) + return 0; + + if (space >= nbits) + return (map[index] >> offset) & BITMAP_LAST_WORD_MASK(nbits); + + value_low = map[index] & BITMAP_FIRST_WORD_MASK(start); + value_high = map[index + 1] & BITMAP_LAST_WORD_MASK(start + nbits); + return (value_low >> offset) | (value_high << space); +} + +/** + * bitmap_write - write n-bit value within a memory region + * @map: address to the bitmap memory region + * @value: value to write, clamped to nbits + * @start: bit offset of the n-bit value + * @nbits: size of value in bits, nonzero, up to BITS_PER_LONG. + * + * bitmap_write() behaves as-if implemented as @nbits calls of __assign_bit(), + * i.e. bits beyond @nbits are ignored: + * + * for (bit = 0; bit < nbits; bit++) + * __assign_bit(start + bit, bitmap, val & BIT(bit)); + * + * Note: callers on 32-bit systems must be careful to not attempt writing more + * than sizeof(unsigned long). + */ +static inline void bitmap_write(unsigned long *map, + unsigned long value, + unsigned long start, unsigned long nbits) +{ + size_t index; + unsigned long offset; + unsigned long space; + unsigned long mask; + bool fit; + + if (unlikely(!nbits || nbits > BITS_PER_LONG)) + return; + + mask = BITMAP_LAST_WORD_MASK(nbits); + value &= mask; + offset = start % BITS_PER_LONG; + space = BITS_PER_LONG - offset; + fit = space >= nbits; + index = BIT_WORD(start); + + map[index] &= (fit ? (~(mask << offset)) : ~BITMAP_FIRST_WORD_MASK(start)); + map[index] |= value << offset; + if (fit) + return; + + map[index + 1] &= BITMAP_FIRST_WORD_MASK(start + nbits); + map[index + 1] |= (value >> space); +} + #endif /* __ASSEMBLY__ */ #endif /* __LINUX_BITMAP_H */