From patchwork Mon Oct 30 15:32:09 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Potapenko X-Patchwork-Id: 159788 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a59:d641:0:b0:403:3b70:6f57 with SMTP id cy1csp2302811vqb; Mon, 30 Oct 2023 08:32:24 -0700 (PDT) X-Google-Smtp-Source: AGHT+IFAEDms/Rb5rvIT9sS+kyBZEcseidOuNdWcYu+M9vXGOJHigrNs+Pcn8rWWm3OE/SVgqP+L X-Received: by 2002:a17:902:d492:b0:1cc:361b:7b10 with SMTP id c18-20020a170902d49200b001cc361b7b10mr3276324plg.24.1698679943912; Mon, 30 Oct 2023 08:32:23 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1698679943; cv=none; d=google.com; s=arc-20160816; b=NupNn7aHI+ddlsbKZbAnCzEdJG67CwM9RUp4QzVa9eh+AvuUxyCww/7x2Z1GojjYRK wxC2fDUsG0w96Y47MS64mWaDq/2VSBxvsX78TsmxAETzeqA0BsRRgZUsudw01kKj69aq h3u3VLO6Q0kZaF614uxCaV9DpEIuTERyZDqvuus/IMQxD3BjN19BQZUSSPm5Glm1pdVi JNj0lidR+GXkK+dbg+yVlQwdMDz0dulRykYXuSaUvOBsj9lMGl57XmgBMgotExwj/P65 HU3GPhKrKI5EURmBjxmQ6Is7XPHDTEY2J7IzK6BNoQKBZpydTe6e3nyr08Iz5WtoBSg8 59PQ== 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=6N1/Pi/gcjpAA6FjFn+3l/Xt1rwHVQqRPaAle2Pb3pE=; fh=GmoqtqK5o+3hw8duGAYBcfcrbmWz8zn7GJB0HJXGJL0=; b=usp8H4OaiAZSAVD+bNBGPyJVzhAceQqaLeaSqqgRKSiNaASfJp4YRDq6XJ1uHGJi/+ +2HL5Hd7LGVOdaGx1nRRxF7cvF1QK6EX0/V1R4Sm104YIjFcQpbFRu4LFcAqN7dWvm2F /gLIaENTPoMjV50PwNs56yirmOFR34j+0Q4c1xEP1OZkrwrocyux9aBC44oSrCBYfN9E bmEHycjhW/H+brA2m0ihGajIoiqNzLgLQUjZsvaay84dggmjdwS/USny6UtpX4jlNm+W jyNFjXgL9m7daeHu6GXmtcsxMCQGJ/kJEAQHd/0XdVob6MN82vTTPtXo6IK2N8PKWj5d yAkQ== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@google.com header.s=20230601 header.b=PDevyMiF; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:7 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. [2620:137:e000::3:7]) by mx.google.com with ESMTPS id h21-20020a170902f7d500b001c32fe6cdf9si4265959plw.386.2023.10.30.08.32.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 30 Oct 2023 08:32:23 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:7 as permitted sender) client-ip=2620:137:e000::3:7; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20230601 header.b=PDevyMiF; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:7 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 C7A51806CC3C; Mon, 30 Oct 2023 08:32:22 -0700 (PDT) X-Virus-Status: Clean X-Virus-Scanned: clamav-milter 0.103.10 at snail.vger.email Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233652AbjJ3PcT (ORCPT + 32 others); Mon, 30 Oct 2023 11:32:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46404 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231395AbjJ3PcS (ORCPT ); Mon, 30 Oct 2023 11:32:18 -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 B276EA9 for ; Mon, 30 Oct 2023 08:32:15 -0700 (PDT) Received: by mail-yw1-x114a.google.com with SMTP id 00721157ae682-5afacc566f3so33968447b3.3 for ; Mon, 30 Oct 2023 08:32:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1698679935; x=1699284735; darn=vger.kernel.org; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=6N1/Pi/gcjpAA6FjFn+3l/Xt1rwHVQqRPaAle2Pb3pE=; b=PDevyMiFtadfy1oGCZNkRZSCcoVpLXLoegg6AfkcOvk6dE9LGuybfvqE+6vVbeDdNV bx346ysh6hlIZ2bGTlBKIldqd4GAbydAmfg8cSmmmcAM4xYirWQqsCBg1l+XPQVONuIo ql0kcXaOwGIRsxjr2t0JeyH8skrKfveAh2G0eCDK61e8bVAp6OqaS11lLox1TRy9OfCw GhBDlmLueJtS6ifsR1akumvSAXTPmq9utJh5ZEbUXwlsZoXfNdtk274hvnRRPcxFj2tg MDGjcQPbQZs6B2JpusQT9vrWXT36ebkCFqrnsBRJG5G41LirpiB5MA7lEjAPR/9nnY3Q 5Qlw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1698679935; x=1699284735; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=6N1/Pi/gcjpAA6FjFn+3l/Xt1rwHVQqRPaAle2Pb3pE=; b=AzaMPILwC71jtqbDugMDxatR6Qpy3LvKW8MS74pl5SFOsNGSA3miIGhu0GjpfhaLJK o6ZvWbA0qkeaVjo0qtIw6tsSzzoyH23WSQUI0JZzWKIYWQoyJ9Kce/ugQGU2LG01xaOG yLwG0XUP0Dn+0Ya3uaScLLGh5e11ZpyudsJorsoofOkQvOAAKogTcr6WManYPKL8yAkR NjqWmWHAV4KyYT0Mocn1mfFc7w1RjpQ4Y/7E7FfLmj77KLtlr/IEH0lbSW6lD3vTzrNy Ck7Dq4irI7KDuwCoYu0wlxns9btQ/HQmXQQltdr8XGVHRuPzwyZpBY//8lNQaCJEhrC8 GdzA== X-Gm-Message-State: AOJu0YwVRVqCTQhxOXJjKICHj+t83/J7fWITv4d+jfIDD7MXdnlb/Gvl 3HlR9XjdHI2JFyE8UdfpUUz0KZQRHwg= X-Received: from glider.muc.corp.google.com ([2a00:79e0:9c:201:132e:31bc:8300:d4e1]) (user=glider job=sendgmr) by 2002:a25:ad5a:0:b0:d90:e580:88e5 with SMTP id l26-20020a25ad5a000000b00d90e58088e5mr184178ybe.10.1698679934767; Mon, 30 Oct 2023 08:32:14 -0700 (PDT) Date: Mon, 30 Oct 2023 16:32:09 +0100 Mime-Version: 1.0 X-Mailer: git-send-email 2.42.0.820.g83a721a137-goog Message-ID: <20231030153210.139512-1-glider@google.com> Subject: [PATCH v11 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=-9.6 required=5.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, RCVD_IN_DNSWL_BLOCKED,SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net 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]); Mon, 30 Oct 2023 08:32:22 -0700 (PDT) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1781195020986245551 X-GMAIL-MSGID: 1781195020986245551 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 */