From mboxrd@z Thu Jan 1 00:00:00 1970 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 293D4E81DFE for ; Fri, 6 Oct 2023 13:46:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232538AbjJFNqH (ORCPT ); Fri, 6 Oct 2023 09:46:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58982 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232530AbjJFNpx (ORCPT ); Fri, 6 Oct 2023 09:45:53 -0400 Received: from mail-yw1-x114a.google.com (mail-yw1-x114a.google.com [IPv6:2607:f8b0:4864:20::114a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3EEAA19F for ; Fri, 6 Oct 2023 06:45:38 -0700 (PDT) Received: by mail-yw1-x114a.google.com with SMTP id 00721157ae682-59e8ebc0376so29390987b3.2 for ; Fri, 06 Oct 2023 06:45:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1696599936; x=1697204736; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=FVc3w80Slds1rDJeGDtC5d5l1mYuX/jp9UzDI84XpOg=; b=v3UbX2CqS7W30A+nhyshcgQVxcFgh2c7QdExDVSdunWpt0UDi6FRpnwSLCyJIGFn0W ye6zGHTb/Kz2OvEozN3jkHEkt0htrlykzF8orwyGP5uWDoBw83TqMSVJ7dgAWaSNJ0pZ ViqIpNh6lCJWiI/HPlDIScpJYgaEfarFyGLW0fljnPJCs0tj50SCmYpnMwkXqCg2l16F +p0oNzsYsqTCoT+q4ErM7BnQqYcEi4CMRL83LZnWw6X/THYPrbdYBYkkujpx9OEo5v8a 6ijNjpgfrMv9YdDodVVbSvdXV56alkB+ND72WPqhEXEMOjd960C4oIPGteZu94MOmx07 yHgg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1696599936; x=1697204736; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=FVc3w80Slds1rDJeGDtC5d5l1mYuX/jp9UzDI84XpOg=; b=HI34eIFh5jev0SoqNYRijUSb3AOMK/rEr1WsSmZD55xgh6ruG+D81jAIlmITYc33X+ x6IwLzKgoXD+VGa2t2JoVYlaZ6jvdnXV8/E0mPOUaIJG5t9sV8GAjR4ThjDfoFbKO1k9 k3gIg+el1+SAeepZEMd5xdFPYBxu7Jkj8BBX3Dl+4qHeDbzBTUJyDBFEAbLpE3kSW9Qa Gqpn2sJIi+htxuNL8PauSoDayROlffJ4A3JYeFYTrAaMREoI2RmfXuHi5EW5+HZ4q3ut Q5KfwLlPGk/nY9hivfPMj9vcEs+ebVALHg6iRM8P/mAltaF+2/DjCOiG/jM3Am11S9Rp 6bHQ== X-Gm-Message-State: AOJu0YyAstYQNeEvZ+dxEZ89z+BGMQxv9bC0nkEe/5dEQVOe4UC+qis3 7AufFNKqv+GZRJRRPcQR13qe49XC4hc= X-Google-Smtp-Source: AGHT+IGBAwP4WDOXMvPWUp8IcF7MTJBHGAe+KbBVrfCsWOIPDnl6zmllpTVlILvsZDLh/Z18+aAlyE1J9ho= X-Received: from glider.muc.corp.google.com ([2a00:79e0:9c:201:2691:23e9:f01f:964]) (user=glider job=sendgmr) by 2002:a05:6902:13cc:b0:d91:8876:2040 with SMTP id y12-20020a05690213cc00b00d9188762040mr133955ybu.5.1696599936015; Fri, 06 Oct 2023 06:45:36 -0700 (PDT) Date: Fri, 6 Oct 2023 15:45:25 +0200 In-Reply-To: <20231006134529.2816540-1-glider@google.com> Mime-Version: 1.0 References: <20231006134529.2816540-1-glider@google.com> X-Mailer: git-send-email 2.42.0.609.gbb76f46606-goog Message-ID: <20231006134529.2816540-2-glider@google.com> Subject: [PATCH v6 1/5] 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 Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, eugenis@google.com, syednwaris@gmail.com, william.gray@linaro.org, Arnd Bergmann Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 called "lib/bitmap: add bitmap_{set,get}_value()" (https://lore.kernel.org/lkml/20230720173956.3674987-2-glider@google.com/) 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 | 68 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 68 insertions(+) diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h index 03644237e1efb..e72c054d21d48 100644 --- a/include/linux/bitmap.h +++ b/include/linux/bitmap.h @@ -76,7 +76,11 @@ struct device; * bitmap_to_arr32(buf, src, nbits) Copy nbits from buf to u32[] dst * 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_read(map, start, nbits) Read an nbits-sized value from + * map at start * bitmap_set_value8(map, value, start) Set 8bit value to 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 @@ -583,6 +587,33 @@ static inline unsigned long bitmap_get_value8(const unsigned long *map, return (map[index] >> offset) & 0xFF; } +/** + * 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. + */ +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)) + return 0; + if (space >= nbits) + return (map[index] >> offset) & GENMASK(nbits - 1, 0); + 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_set_value8 - set an 8-bit value within a memory region * @map: address to the bitmap memory region @@ -599,6 +630,43 @@ static inline void bitmap_set_value8(unsigned long *map, unsigned long value, map[index] |= value << offset; } +/** + * 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 similarly to @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)); + */ +static inline void bitmap_write(unsigned long *map, + unsigned long value, + 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 mask; + + if (unlikely(!nbits)) + return; + mask = BITMAP_LAST_WORD_MASK(nbits); + value &= mask; + if (space >= nbits) { + map[index] &= ~(mask << offset); + map[index] |= value << offset; + return; + } + map[index] &= ~BITMAP_FIRST_WORD_MASK(start); + map[index] |= value << offset; + map[index + 1] &= ~BITMAP_LAST_WORD_MASK(start + nbits); + map[index + 1] |= (value >> space); +} + #endif /* __ASSEMBLY__ */ #endif /* __LINUX_BITMAP_H */ -- 2.42.0.609.gbb76f46606-goog