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[23.128.96.36]) by mx.google.com with ESMTPS id s64-20020a815e43000000b0059f4a492ebasi11491903ywb.195.2023.10.25.01.38.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 25 Oct 2023 01:38:43 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.36 as permitted sender) client-ip=23.128.96.36; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20230601 header.b=NKU8wYhu; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.36 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 CF2998029088; Wed, 25 Oct 2023 01:38:40 -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 S233846AbjJYIiV (ORCPT + 26 others); Wed, 25 Oct 2023 04:38:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:32792 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232720AbjJYIiU (ORCPT ); Wed, 25 Oct 2023 04:38:20 -0400 Received: from mail-wr1-x449.google.com (mail-wr1-x449.google.com [IPv6:2a00:1450:4864:20::449]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D15EE9C for ; Wed, 25 Oct 2023 01:38:17 -0700 (PDT) Received: by mail-wr1-x449.google.com with SMTP id ffacd0b85a97d-32d933caa8eso2177511f8f.1 for ; Wed, 25 Oct 2023 01:38:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1698223096; x=1698827896; darn=vger.kernel.org; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=7RZQ/S/jTVrRUSUeijWCI7Egf5o6MgvN5jmxkKIprg8=; b=NKU8wYhuHe6s/GJVxB4BIoEmOD5bvotR03z7nMzT96bCwduK15eUchUWmYbLVQl5a5 e9zjE0ktEwUhr8LyYo60OJrDSPHHEorf6Gqu3TwkWSIe73QNSGgIQQyLMbTQp8fiVGAG uZlL5HIdsFXd2teynRNC903X8Kb3sIg3rfXsgyBBu5E/jtlh2upQeyIooyLw4WzcXpB8 eLGjmonvHZaim5f8aTve9DdGViiJvyNI0LTthhIIClZ88pZAUmKKamx5Yegi0KvZlqjX KLJDuBTCzS9r0GwW2GAgC6Uok+ntOoek/BPovo78NYQni8Bse7El6BVHOGfGCsxbHUUk g8sw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1698223096; x=1698827896; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=7RZQ/S/jTVrRUSUeijWCI7Egf5o6MgvN5jmxkKIprg8=; b=w850uPjU/0boD15dPs3cMokTz54+cvlf6NGIzZEXyk2FvLGGxdJAOMkKZ+URGgLu9M /gilYoDGF3BBbAmFxeubKTlyv5QOqjcZOB4HJNpGBL36LxqGtHEvH4Ma9b8o7SkIMBIi CdKP+7o3eF5FDAGVGArNrWRqsuPr/bmGU3bAdTcYN4292vLNCVb/uzvMfRFTj1DpGEHB /ccIhVLcUmtuMIYc+WF3NryD9JUTddGYuVYSGJ3EAQUE5NMxrE212Wla4pwC3enc9VME 5X8HGb4V7UgUOygC3a6pit5frOTBx+Cd0q3duA1x0v64H39N0buj52/RTA+yvo6SiY9Q ffnA== X-Gm-Message-State: AOJu0Yy00ENfRTGKyYa70Wyongv7b/3vogLQnwT3EH0eoZMfnfQ+LXQF LfXaBPReCxRb+sV4QIVfOB4eyzOYplc= X-Received: from glider.muc.corp.google.com ([2a00:79e0:9c:201:541d:37f9:e2bc:817b]) (user=glider job=sendgmr) by 2002:a5d:4d07:0:b0:319:6fc6:151 with SMTP id z7-20020a5d4d07000000b003196fc60151mr115747wrt.10.1698223095931; Wed, 25 Oct 2023 01:38:15 -0700 (PDT) Date: Wed, 25 Oct 2023 10:38:11 +0200 Mime-Version: 1.0 X-Mailer: git-send-email 2.42.0.758.gaed0368e0e-goog Message-ID: <20231025083812.456916-1-glider@google.com> Subject: [PATCH v9 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]); Wed, 25 Oct 2023 01:38:40 -0700 (PDT) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1780716010099740718 X-GMAIL-MSGID: 1780716010099740718 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 */