From patchwork Mon May 6 03:33:52 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yafang Shao X-Patchwork-Id: 13654875 X-Patchwork-Delegate: bpf@iogearbox.net Received: from mail-oi1-f172.google.com (mail-oi1-f172.google.com [209.85.167.172]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 710F93D967 for ; Mon, 6 May 2024 03:35:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.167.172 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714966522; cv=none; b=ocRusaIRDJyklQlG9QbZqYl2lrUYDJge2gGjgp4lKZD9yaoNMK/9kWlIgPYh5oC8YY1LYecvepyu0wBaEUoxMnPJR8120vHczIBWfJQsdG4PhnCVFUZ6qYSoNWwuzpto2W2w3PAX1IiiEGnRKCcgpEqpgctDlAwetbcGGhJOjXc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714966522; c=relaxed/simple; bh=8JgLxe4FF8VWT99yRlmwEFdp1bakUQNZOmlV2krhXs0=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=RKFap2L1vzz/m0mM7I7NJyPVd39rjEUvdXM5wfr1wbZCidVf3RZ5F7UscC2C7CSuFwp9jVsXem66AebGL5SV6tGEt4xMzT2f9Gig7KbHL+TYuk3AYBK9eyQphrxuVYWRlsGk7KkF6Pj2wV7EidSsr//qDvFJJ5OfJ1lfDOJMK4Y= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=YtNzA8dS; arc=none smtp.client-ip=209.85.167.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="YtNzA8dS" Received: by mail-oi1-f172.google.com with SMTP id 5614622812f47-3c963880aecso452338b6e.3 for ; Sun, 05 May 2024 20:35:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1714966519; x=1715571319; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=I7s/xylKbOObjev5dMW3NX3FOGC2ODYCJIgRjU7bz/4=; b=YtNzA8dS7xffzEb8LE4wNuPTgqfpsHhtHmoU2fFNBlTmRMEclC+2dvkA8mWD5xMA5u h1fI82Mh/YAwIq3RjsUxCREL2qLhmlZ7tDial1skO86sXJTUzVG2wITMhu83Ec/wHX6y GNkeZQJLPVoYQ8tuvCApxMAJ5DmId9uO0v0qjkwqPoadLVjaqhyM90wxwi0TFbAEyKqo NRZwLe/fxHi41uk5Y41eg7XkBi5qH7uG0ppx75jaYFRnP/D32q8c5MpKC5c+j4w6rukK zdQIdOp24GtNbCCwJjJibn2UcJN3LOaU44yaINm6qHKOmWay5itx2hEqPPkKq6O93WRB WHpQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1714966519; x=1715571319; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=I7s/xylKbOObjev5dMW3NX3FOGC2ODYCJIgRjU7bz/4=; b=qc+dVRFxjQiSKR0B228iPEgT/lCrFApjaLrNrqOyhlzMPcCB/Gd7w/nMQA0vJX3f+s UJ7Dxb2Dn5f1HNdSEqcPRLGZOGSHexx13Vh9WDM3GobVVoq4mYHZbxrh7oKbVzJb9sGq 2CoqRDRDYQ7f06FBHNIxwLt0460XZ/6ijmgEC2xUIrxnW/uPUYUSx1jdIUujWEra3KN9 cS/JcmvEFGapax01AQmLEtm6juQ6RjbMeGwk+nbTGihROkNy2l+U3vgAl/NnSF4ZVLbo 8WC2XG1V+ecMu1NRqeQBT4hXyGst3c0t2rUo5ZuWH6MaFAG7zgrwQUas/xksa8PPxWCf 1RtA== X-Gm-Message-State: AOJu0YyjkOsjRWYBvoGDMFgHf+MCx4zGfB5wVJ8mbvNJM981h1zqvPWa goqKpegCUGOTQjDJ7bRrDSSUpX9ePCy343j+PyZ3rMmiaJ8M8SfL X-Google-Smtp-Source: AGHT+IF+++HjCE+qYLcoq16PymHpq22f+xVuXptc2Vb8KQ5uISbNP8XqN1dgmjRKk8UmG8AE07CaBw== X-Received: by 2002:a05:6808:4d3:b0:3c9:70eb:151b with SMTP id a19-20020a05680804d300b003c970eb151bmr572358oie.59.1714966519562; Sun, 05 May 2024 20:35:19 -0700 (PDT) Received: from localhost.localdomain ([39.144.105.178]) by smtp.gmail.com with ESMTPSA id g9-20020aa79dc9000000b006f33c0aee44sm6897539pfq.91.2024.05.05.20.35.12 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Sun, 05 May 2024 20:35:19 -0700 (PDT) From: Yafang Shao To: ast@kernel.org, daniel@iogearbox.net, john.fastabend@gmail.com, andrii@kernel.org, martin.lau@linux.dev, eddyz87@gmail.com, song@kernel.org, yonghong.song@linux.dev, kpsingh@kernel.org, sdf@google.com, haoluo@google.com, jolsa@kernel.org Cc: bpf@vger.kernel.org, Yafang Shao Subject: [PATCH v7 bpf-next 1/2] bpf: Add bits iterator Date: Mon, 6 May 2024 11:33:52 +0800 Message-Id: <20240506033353.28505-2-laoar.shao@gmail.com> X-Mailer: git-send-email 2.30.1 (Apple Git-130) In-Reply-To: <20240506033353.28505-1-laoar.shao@gmail.com> References: <20240506033353.28505-1-laoar.shao@gmail.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: bpf@iogearbox.net Add three new kfuncs for the bits iterator: - bpf_iter_bits_new Initialize a new bits iterator for a given memory area. Due to the limitation of bpf memalloc, the max number of bits that can be iterated over is limited to (4096 * 8). - bpf_iter_bits_next Get the next bit in a bpf_iter_bits - bpf_iter_bits_destroy Destroy a bpf_iter_bits The bits iterator facilitates the iteration of the bits of a memory area, such as cpumask. It can be used in any context and on any address. Signed-off-by: Yafang Shao --- kernel/bpf/helpers.c | 140 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 140 insertions(+) diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index 2a69a9a36c0f..83b2a02f795f 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -2744,6 +2744,143 @@ __bpf_kfunc void bpf_preempt_enable(void) preempt_enable(); } +struct bpf_iter_bits { + __u64 __opaque[2]; +} __aligned(8); + +struct bpf_iter_bits_kern { + union { + unsigned long *bits; + unsigned long bits_copy; + }; + u32 nr_bits; + int bit; +} __aligned(8); + +/** + * bpf_iter_bits_new() - Initialize a new bits iterator for a given memory area + * @it: The new bpf_iter_bits to be created + * @unsafe_ptr__ign: A ponter pointing to a memory area to be iterated over + * @nr_bits: The number of bits to be iterated over. Due to the limitation of + * memalloc, it can't greater than (4096 * 8). + * + * This function initializes a new bpf_iter_bits structure for iterating over + * a memory area which is specified by the @unsafe_ptr__ign and @nr_bits. It + * copy the data of the memory area to the newly created bpf_iter_bits @it for + * subsequent iteration operations. + * + * On success, 0 is returned. On failure, ERR is returned. + */ +__bpf_kfunc int +bpf_iter_bits_new(struct bpf_iter_bits *it, const void *unsafe_ptr__ign, u32 nr_bits) +{ + struct bpf_iter_bits_kern *kit = (void *)it; + u32 words = BITS_TO_LONGS(nr_bits); + u32 size = BITS_TO_BYTES(nr_bits); + u32 left, offset; + int err; + + BUILD_BUG_ON(sizeof(struct bpf_iter_bits_kern) != sizeof(struct bpf_iter_bits)); + BUILD_BUG_ON(__alignof__(struct bpf_iter_bits_kern) != + __alignof__(struct bpf_iter_bits)); + + if (!unsafe_ptr__ign || !nr_bits) { + kit->bits = NULL; + return -EINVAL; + } + + kit->nr_bits = 0; + kit->bits_copy = 0; + /* Optimization for u64/u32 mask */ + if (nr_bits <= 64) { + /* For big-endian, we must calculate the offset */ + offset = IS_ENABLED(CONFIG_S390) ? sizeof(u64) - size : 0; + + err = bpf_probe_read_kernel_common(((char *)&kit->bits_copy) + offset, + size, unsafe_ptr__ign); + if (err) + return -EFAULT; + + kit->nr_bits = nr_bits; + kit->bit = -1; + return 0; + } + + /* Fallback to memalloc */ + kit->bits = bpf_mem_alloc(&bpf_global_ma, size); + if (!kit->bits) + return -ENOMEM; + + err = bpf_probe_read_kernel_common(kit->bits, words * sizeof(u64), unsafe_ptr__ign); + if (err) { + bpf_mem_free(&bpf_global_ma, kit->bits); + return err; + } + + /* long-aligned */ + left = size & (sizeof(u64) - 1); + if (!left) + goto out; + + offset = IS_ENABLED(CONFIG_S390) ? sizeof(u64) - left : 0; + err = bpf_probe_read_kernel_common((char *)(kit->bits + words - 1) + offset, left, + unsafe_ptr__ign + (words - 1) * sizeof(u64)); + if (err) { + bpf_mem_free(&bpf_global_ma, kit->bits); + return err; + } + +out: + kit->nr_bits = nr_bits; + kit->bit = -1; + return 0; +} + +/** + * bpf_iter_bits_next() - Get the next bit in a bpf_iter_bits + * @it: The bpf_iter_bits to be checked + * + * This function returns a pointer to a number representing the value of the + * next bit in the bits. + * + * If there are no further bit available, it returns NULL. + */ +__bpf_kfunc int *bpf_iter_bits_next(struct bpf_iter_bits *it) +{ + struct bpf_iter_bits_kern *kit = (void *)it; + u32 nr_bits = kit->nr_bits; + const unsigned long *bits; + int bit; + + if (nr_bits == 0) + return NULL; + + bits = nr_bits <= 64 ? &kit->bits_copy : kit->bits; + bit = find_next_bit(bits, nr_bits, kit->bit + 1); + if (bit >= nr_bits) { + kit->nr_bits = 0; + return NULL; + } + + kit->bit = bit; + return &kit->bit; +} + +/** + * bpf_iter_bits_destroy() - Destroy a bpf_iter_bits + * @it: The bpf_iter_bits to be destroyed + * + * Destroy the resource associated with the bpf_iter_bits. + */ +__bpf_kfunc void bpf_iter_bits_destroy(struct bpf_iter_bits *it) +{ + struct bpf_iter_bits_kern *kit = (void *)it; + + if (kit->nr_bits <= 64) + return; + bpf_mem_free(&bpf_global_ma, kit->bits); +} + __bpf_kfunc_end_defs(); BTF_KFUNCS_START(generic_btf_ids) @@ -2826,6 +2963,9 @@ BTF_ID_FLAGS(func, bpf_wq_set_callback_impl) BTF_ID_FLAGS(func, bpf_wq_start) BTF_ID_FLAGS(func, bpf_preempt_disable) BTF_ID_FLAGS(func, bpf_preempt_enable) +BTF_ID_FLAGS(func, bpf_iter_bits_new, KF_ITER_NEW) +BTF_ID_FLAGS(func, bpf_iter_bits_next, KF_ITER_NEXT | KF_RET_NULL) +BTF_ID_FLAGS(func, bpf_iter_bits_destroy, KF_ITER_DESTROY) BTF_KFUNCS_END(common_btf_ids) static const struct btf_kfunc_id_set common_kfunc_set = {