From patchwork Thu Oct 26 13:59:11 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Potapenko X-Patchwork-Id: 13437601 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 CEE54C25B48 for ; Thu, 26 Oct 2023 13:59:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:Cc:To:From:Subject:Message-ID: Mime-Version:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To: References:List-Owner; bh=bBn/EFLqiEOq3qB+hLKKdQpOfq7KSXcZaW41U8uq+rs=; b=jxX r0zZR6aeI1ZxHZuLeUEku1bt6nfHidBG4FqphpE9VH/dhOsgn315FYEcJEKQu3h+SOwly0ph6ZOwX lxD5XurFm/2pi+oPiehjQT3GfrYRgjXlmK3VVuU8rwi8Jy5VyN/XisFRGgJndaidJcyBv3MAREVfD wYgtewleeIsObLXkrpk0DT/ncrtd18ZTotjin7dtsGHi4MXq89KU21vFcw63xaxlZeJf2Zz6HpxpK eVFIJ+DBATp4rINC+nk+lKpBJWarKKqCElAW8EokDoz5+FF8Vlfbi4/ah+pSsbeogHiu8bKOAwrVi DNP5iQvTIRq/T6GwMAeiPpruEWVLEzQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qw0tQ-00EbVy-1B; Thu, 26 Oct 2023 13:59:24 +0000 Received: from mail-yw1-x114a.google.com ([2607:f8b0:4864:20::114a]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1qw0tN-00EbUf-0A for linux-arm-kernel@lists.infradead.org; Thu, 26 Oct 2023 13:59:22 +0000 Received: by mail-yw1-x114a.google.com with SMTP id 00721157ae682-5af16e00fadso4579857b3.0 for ; Thu, 26 Oct 2023 06:59:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1698328757; x=1698933557; darn=lists.infradead.org; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=dAvhcHsUDf2ItWBwevxZ96vnhxr2cV7fa3pJ8laFriQ=; b=4BE+inxYnP4kzQU+Ri69/tFKcdG13LqaJMhP53dpJZlMWaN0q8O28IpoZVxDEURiLr m0GSMk2TlC2Z/Bu3bx5zgRiVom7YW+eRtaLNBWtdT7eRRrKeK15BOVaPl1uEju8MAfFe OtrqHXpRM9Lrrv1dBqrmfCSizlPmMISPevKrfmzWHZfgK2/YHkon4MtBHlh5UtfsYJEn 5MkBXvvTMyCTvpb2xfWsBcobhlArpqGgnfGuwKzmPLCLFkP7NAURwJRMMM/EPN1qP9zv wIe8QKen6lwBWLbxClDZ58r4xreE21YKke5OudyV5i7J+8/ZmMfwa0lP1scx44LaaSag EeuA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1698328757; x=1698933557; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=dAvhcHsUDf2ItWBwevxZ96vnhxr2cV7fa3pJ8laFriQ=; b=vbnj/5SD5ojX26EwhKCjqaF7B+nYpTlo6JtVnPOCQI8soXLdhzGy8SaIiINEEPQFD/ QLVwNe+ujGaOhQkX9rrJ9LglxnU2nnCDrBoRm3SEUNLhLXwolEDdHPpY1pxjUqTqkAYk uIfmt36nKnLYSuqz9UFoT2E3l+F3z39NS2Qfde3Qmmt99FtZw/RxncUXVmIlThlNvr8K +IZGfss/yRzaTifib5aS85gG96GyGZc4JVvFESRjRkK0KVnQISu33tJitAMbzOP1XtRK jbegOdg/MzQcXVMxkg6vd4O6zpwrB49NybTNj1B+tv6oFLZ6MbZ8+DYIBghyKK5dQO38 63fQ== X-Gm-Message-State: AOJu0YyKzD/ich7tBvfzIU7jqTcSXh9ZX0XI0R2UMcTfAkjyDiCFgzEu 6sGco68pyM7VauUx9r5FRxoqHdGwnnQ= X-Google-Smtp-Source: AGHT+IHmqu+xm52i+2qdyGMYMMhJu9qdDuWVKux5zs41eCdBdXh+8OqMMbqhiOis7A+oMvvNTcqv3IleSUw= X-Received: from glider.muc.corp.google.com ([2a00:79e0:9c:201:6c48:d4b4:c637:b013]) (user=glider job=sendgmr) by 2002:a0d:dfc3:0:b0:5a8:28e5:ca68 with SMTP id i186-20020a0ddfc3000000b005a828e5ca68mr416013ywe.5.1698328756969; Thu, 26 Oct 2023 06:59:16 -0700 (PDT) Date: Thu, 26 Oct 2023 15:59:11 +0200 Mime-Version: 1.0 X-Mailer: git-send-email 2.42.0.758.gaed0368e0e-goog Message-ID: <20231026135912.1214302-1-glider@google.com> Subject: [PATCH v10 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-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20231026_065921_095996_F3CA7C15 X-CRM114-Status: GOOD ( 19.65 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.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 Reviewed-by: Andy Shevchenko --- 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/) v10: - update comments as requested by Andy Shevchenko 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 | 78 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 78 insertions(+) diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h index 03644237e1efb..f5745b505a194 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 +603,80 @@ 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 bits located at the @start bit offset within the + * @map memory region. For @nbits = 0 and @nbits > BITS_PER_LONG the return + * value is undefined. + */ +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)); + * + * For @nbits > BITS_PER_LONG no writes are performed. + */ +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 */