From patchwork Sun Mar 31 03:41:53 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yafang Shao X-Patchwork-Id: 13611792 X-Patchwork-Delegate: bpf@iogearbox.net Received: from mail-pl1-f173.google.com (mail-pl1-f173.google.com [209.85.214.173]) (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 122CD110A for ; Sun, 31 Mar 2024 03:44:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.173 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711856676; cv=none; b=hSEt6iw8UbfiPrueAuNtUhNXKjnKuF+ryRnvmL7/AWjH8rvx4E7fjDAxVnW9OoDYB69CNvLLW5eBnExaCuKZGNZAO56/pZXgBlps/CuVcvumRQsgguWZ1QWjFmygpUfZnfexoFgwpFwY8KVdM6bcK7XLF8NBQlCMX3HcMSbqrlY= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711856676; c=relaxed/simple; bh=dTOH/jT+xl9iMYSWoSvujdD0ZbqUZR86+BcR/iEq6VQ=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=L5nlZmvdQ5OtuKsuWmZzfgCc/i/LPaQbYl11T2SjXrWp2G01naFiPmGTHaQObuIiU7fAmTe1nUwT/wYBJ4na73n9/iM+cxkxd4JD3R7wsxMJZsd6YhWsVz4ImhMEAlM3g6uhQy26O+FJiL1m/KZLwq5J9UcmWUEc0AmKE4CybCA= 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=WuJQVKvH; arc=none smtp.client-ip=209.85.214.173 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="WuJQVKvH" Received: by mail-pl1-f173.google.com with SMTP id d9443c01a7336-1e24985beadso2706825ad.1 for ; Sat, 30 Mar 2024 20:44:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1711856674; x=1712461474; 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=P2RRJnLxVo1hxqPOCx7ze6xs5wfBeyecuePLuk6TwxI=; b=WuJQVKvH0zAHp1nKX1RGYhjeSVYQbR4Y0JDvxja9lQoauR+6WPO8CSzQqFJGsgMSVu IB/Y/7vR9Tny9pNKAHEBghG4zBFoBQ+cZHMGvzYCnfxXnmBkmwUhl31oU2kCcmmH07nd tFH3IN1MWn7rgXzU83XwZAmGN+Lb0fIA7wWqo89GefBlDxl0JYVt1zZhE+cFXBZ4cPdA OgZ+UYltXVPrA5kHrpl5LOSq9VFfftcrCaCCX2/LWMjebR8vwrY/kBNgzIGvyqtQh3w9 jszcwTiGn0ESOLLENAZ0rMorrY7nhVAEOjCmNIQAN8bqeLR6ovrMqMspJlwrYAXzDwMz OpFA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1711856674; x=1712461474; 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=P2RRJnLxVo1hxqPOCx7ze6xs5wfBeyecuePLuk6TwxI=; b=XjXCdgH++WHk9+vZpS9mmwXfNzocjB36qmVniFPBx317t8PPzafCaF/X5VxeihRtFF 8e8jUzC7TZEr1g4Pi2x/uAzUMYaiTSxEf5bi2Tp5cXyPfSXdtlTi9TxDYZopR9ExoshZ yG0Is+XcGP/67n3DF8LaYIDs1qI841HfrIkGuOt7X7zJGeRtg2Tl64F1p4BPqWHGdvrm pCSR6ZKklgwPekKkPjb1GyfS24CuQQLKvL4mP/KrYZi6wr5DWHhfNVlFrGNoQzRoeV4Z saAKfXwej1sEQoMKK7WGMlNrAtyl5zRNPGj522A+w94B+y8I8dyZczaht3JJaq2IrrjZ vYCQ== X-Gm-Message-State: AOJu0YwiPhI6SYH1Bh0AMBLV7a4KqLQFh0wzgmXo4Pk59T70D75773To 9OgI3MiEPtMMAPEcO+H8hSEPaeIK54GWWFBKD6XvOKDyBsk/CrzC X-Google-Smtp-Source: AGHT+IHX3sLMTqiLqhZDi76p1muBuH2nOBOIK1pDowXseK+j55RmX209idMJhtbkZ9RXHPa1Dd5dBw== X-Received: by 2002:a17:903:446:b0:1e0:cea:257e with SMTP id iw6-20020a170903044600b001e00cea257emr9909542plb.2.1711856674257; Sat, 30 Mar 2024 20:44:34 -0700 (PDT) Received: from localhost.localdomain ([39.144.105.37]) by smtp.gmail.com with ESMTPSA id y19-20020a170902e19300b001dcfc68e7desm6030239pla.75.2024.03.30.20.44.22 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Sat, 30 Mar 2024 20:44:33 -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 bpf-next v5 1/2] bpf: Add bits iterator Date: Sun, 31 Mar 2024 11:41:53 +0800 Message-Id: <20240331034154.16284-2-laoar.shao@gmail.com> X-Mailer: git-send-email 2.30.1 (Apple Git-130) In-Reply-To: <20240331034154.16284-1-laoar.shao@gmail.com> References: <20240331034154.16284-1-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 Acked-by: Andrii Nakryiko --- kernel/bpf/helpers.c | 120 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 120 insertions(+) diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index d9e7aca8ae9e..dec5d3ccd25b 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -2549,6 +2549,123 @@ __bpf_kfunc void bpf_throw(u64 cookie) WARN(1, "A call to BPF exception callback should never return\n"); } +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) +{ + u32 size = BITS_TO_LONGS(nr_bits) * sizeof(unsigned long); + struct bpf_iter_bits_kern *kit = (void *)it; + 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) { + err = bpf_probe_read_kernel_common(&kit->bits_copy, 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, size, unsafe_ptr__ign); + if (err) { + bpf_mem_free(&bpf_global_ma, kit->bits); + return err; + } + + 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) @@ -2626,6 +2743,9 @@ BTF_ID_FLAGS(func, bpf_dynptr_is_rdonly) BTF_ID_FLAGS(func, bpf_dynptr_size) BTF_ID_FLAGS(func, bpf_dynptr_clone) BTF_ID_FLAGS(func, bpf_modify_return_test_tp) +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 = {