From patchwork Thu Nov 9 15:11:04 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Potapenko X-Patchwork-Id: 163413 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a59:b129:0:b0:403:3b70:6f57 with SMTP id q9csp501121vqs; Thu, 9 Nov 2023 07:12:02 -0800 (PST) X-Google-Smtp-Source: AGHT+IHmzZalVCCNIBR0fmePi3BzIVg36nWNAUbpIFmfmIIrd/gXIDoVO5J0aG2qdCxMEUgCecak X-Received: by 2002:a17:902:8488:b0:1cc:4eb0:64cf with SMTP id c8-20020a170902848800b001cc4eb064cfmr4383236plo.52.1699542721844; Thu, 09 Nov 2023 07:12:01 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1699542721; cv=none; d=google.com; s=arc-20160816; b=NZrDEFWn7AHru7BjOlXDJsp2IBq+ggidOXhc2ntLeglfJ3boT36dCetDUCEIIGe7eD cPuSNQ0/laAofgKnB1VyQwfFX8I0igDkO/TFfO3AtxDaTXay7L9zitxQDZTULZKm48um G31zGaGaw282zSJhc7XnoMAiBgLbuij3UjF3h5kl12IJaqvqNluDNnOb0pAx4FSJsucD QTLu9+pKEoTFKzLHsgBnBupSeE+KJrNQuTLnGn/ivJdH4I/nxOUVnJ/mMUB35H7UBB2G D98coFzX9mNOxQbg1CONcGI7kOoy8ohzKJSzbPXxb1vfGESzvUKGbobnOrIrF11f5nt4 fcMw== 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=ep1qJd3r3CicksEB8/VS0CthWKnz6BMcAhHrRuSJk70=; fh=GmoqtqK5o+3hw8duGAYBcfcrbmWz8zn7GJB0HJXGJL0=; b=E5lBpmjftmO6O3CBMcpPPiAf2n+WWPon3fjYy/dnISHaFYVZaV2lX6gbJUzAuPAiKu Hkq77opbT7EIVkKto4A3GILlcyPo6ciLaDHyzDJk8f1UoE1HCRt2WFv8S3EOmQiFyDli a4Zla4sJxxAQ7wAbtLUWIxv0ikCKlldk8pNrFwaNBqiEObbU+IIEdkWwkx0bFzNh5bty DS+5cMAF/njJ8JuEryfgi8MENe1LkZxvu388aANURnh8BLAgLKkCmdqW+M+tU7sxAkTI nXpDVbQyX5XsGZyXiqKCs0YsR3DWXRKinUV5GqsYucVcRCXngQAdItE8z2Rj3KLplp5O o++g== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@google.com header.s=20230601 header.b=QJ7XlpWa; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.37 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 snail.vger.email (snail.vger.email. [23.128.96.37]) by mx.google.com with ESMTPS id q13-20020a170902f34d00b001c9af5305dasi4700747ple.126.2023.11.09.07.12.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 09 Nov 2023 07:12:01 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.37 as permitted sender) client-ip=23.128.96.37; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20230601 header.b=QJ7XlpWa; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.37 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 snail.vger.email (Postfix) with ESMTP id 7249D83DB97B; Thu, 9 Nov 2023 07:11:27 -0800 (PST) X-Virus-Status: Clean X-Virus-Scanned: clamav-milter 0.103.11 at snail.vger.email Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234482AbjKIPLU (ORCPT + 31 others); Thu, 9 Nov 2023 10:11:20 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50982 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234475AbjKIPLS (ORCPT ); Thu, 9 Nov 2023 10:11:18 -0500 Received: from mail-ej1-x649.google.com (mail-ej1-x649.google.com [IPv6:2a00:1450:4864:20::649]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 120B035AB for ; Thu, 9 Nov 2023 07:11:16 -0800 (PST) Received: by mail-ej1-x649.google.com with SMTP id a640c23a62f3a-9bea60bd1adso245098066b.0 for ; Thu, 09 Nov 2023 07:11:15 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1699542674; x=1700147474; darn=vger.kernel.org; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=ep1qJd3r3CicksEB8/VS0CthWKnz6BMcAhHrRuSJk70=; b=QJ7XlpWaG7fCDWTud3QVeuIu3vJGVW1L6iIlIggxrlQb1bV4zkN6Z69j2keJiTbiRC kkXnVY1fX1CsAfT8W8WNjzHBEiBRdsSl9A3obcf3nYZ1uXUK+jrFmHfduR43iUIk+7Bo dti9C0tdAfBZGO6NkcS2JxFNHWvnmFAgZquFLVc4j4HpbqviFVW+a9WShGG+Njsx1SZs YmNF8Bfzi5fhCCl2o1hViHIP3lm11P+z/ONr5Eu6F7xxR/S5O8qPcdRbYRdpYZlYTcLd WK/pJJUuu/H1HjG9yGks/wl2Xne3Rf3xhg7ItFAOG3lClOh5hEQ6bbUeZqHr5qQhi/GR VfwQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1699542674; x=1700147474; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=ep1qJd3r3CicksEB8/VS0CthWKnz6BMcAhHrRuSJk70=; b=bEXQ41Vy2dShDxiGy5FyPjOeJCEMOTyqZVTOBEoBnJ26K7NTXLTSDFKIcDGDOMVvsI 3fHsh9/ozmURp6nnpM27zpWmrojmpgr/E3LAgufoWEWuRqm8VNMpOkSNWB83i/LgDux6 qqkQDGiJj38vgxbKMvPcW6c+gjp3MGHfJgERNvrVkSXOXvBFlLzqaYHft0g70wDFv5OP BRdTbPG3qtLGjaeEHXb+pRZud9eg3bjIEVS4ginuldlM5aBme5uTPsxXHxxGgJwbEnKS tSBbW9SQiLKUIVdb6UEKCZcRlX0LsqqDPrjxOBBdNdPzv6PGbr7XWcnLrxXO5tviURl3 sSQg== X-Gm-Message-State: AOJu0YxlBO9WhVV31hizanCAOsut17K5NT3jdjY+dd6wxfksiT9OPHNW hGQkklDsdqNpl91fZ42wpcMh/yTcc1A= X-Received: from glider.muc.corp.google.com ([2a00:79e0:9c:201:c5e3:4628:e996:9f03]) (user=glider job=sendgmr) by 2002:a17:907:b90:b0:9dd:9808:bed1 with SMTP id ey16-20020a1709070b9000b009dd9808bed1mr91850ejc.7.1699542674589; Thu, 09 Nov 2023 07:11:14 -0800 (PST) Date: Thu, 9 Nov 2023 16:11:04 +0100 Mime-Version: 1.0 X-Mailer: git-send-email 2.42.0.869.gea05f2083d-goog Message-ID: <20231109151106.2385155-1-glider@google.com> Subject: [PATCH v12 1/3] 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 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 (snail.vger.email [0.0.0.0]); Thu, 09 Nov 2023 07:11:27 -0800 (PST) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1782099709218247542 X-GMAIL-MSGID: 1782099709218247542 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/) v11: - rearrange whitespace as requested by Andy Shevchenko, add Reviewed-by:, update a comment 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 | 77 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 77 insertions(+) diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h index 03644237e1efb..7dd00e2e6d539 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 +603,79 @@ 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 == 0 and @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 */