From patchwork Fri Jan 28 23:45:15 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Song Liu X-Patchwork-Id: 12729294 X-Patchwork-Delegate: bpf@iogearbox.net 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C82AFC433F5 for ; Fri, 28 Jan 2022 23:51:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346597AbiA1XvR convert rfc822-to-8bit (ORCPT ); Fri, 28 Jan 2022 18:51:17 -0500 Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:35812 "EHLO mx0b-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344885AbiA1XvQ (ORCPT ); Fri, 28 Jan 2022 18:51:16 -0500 Received: from pps.filterd (m0109332.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.1.2/8.16.1.2) with ESMTP id 20SKg2l5025245 for ; Fri, 28 Jan 2022 15:51:16 -0800 Received: from mail.thefacebook.com ([163.114.132.120]) by mx0a-00082601.pphosted.com (PPS) with ESMTPS id 3dv8um6acf-2 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Fri, 28 Jan 2022 15:51:15 -0800 Received: from twshared11487.23.frc3.facebook.com (2620:10d:c085:208::11) by mail.thefacebook.com (2620:10d:c085:11d::7) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.21; Fri, 28 Jan 2022 15:51:14 -0800 Received: by devbig006.ftw2.facebook.com (Postfix, from userid 4523) id DAF5E28E02F9C; Fri, 28 Jan 2022 15:45:37 -0800 (PST) From: Song Liu To: , , CC: , , , , , , , Song Liu Subject: [PATCH v7 bpf-next 7/9] bpf: introduce bpf_prog_pack allocator Date: Fri, 28 Jan 2022 15:45:15 -0800 Message-ID: <20220128234517.3503701-8-song@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220128234517.3503701-1-song@kernel.org> References: <20220128234517.3503701-1-song@kernel.org> MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-ORIG-GUID: Zq4W8ICFPgj5Pc6ykmygyP5jZRXqwfhG X-Proofpoint-GUID: Zq4W8ICFPgj5Pc6ykmygyP5jZRXqwfhG X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.816,Hydra:6.0.425,FMLib:17.11.62.513 definitions=2022-01-28_08,2022-01-28_01,2021-12-02_01 X-Proofpoint-Spam-Details: rule=fb_outbound_notspam policy=fb_outbound score=0 spamscore=0 bulkscore=0 priorityscore=1501 lowpriorityscore=0 impostorscore=0 malwarescore=0 suspectscore=0 clxscore=1015 mlxscore=0 phishscore=0 adultscore=0 mlxlogscore=909 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2201110000 definitions=main-2201280129 X-FB-Internal: deliver Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net Most BPF programs are small, but they consume a page each. For systems with busy traffic and many BPF programs, this could add significant pressure to instruction TLB. Introduce bpf_prog_pack allocator to pack multiple BPF programs in a huge page. The memory is then allocated in 64 byte chunks. Memory allocated by bpf_prog_pack allocator is RO protected after initial allocation. To write to it, the user (jit engine) need to use text poke API. Signed-off-by: Song Liu --- kernel/bpf/core.c | 127 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 127 insertions(+) diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index dc0142e20c72..25e34caa9a95 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -805,6 +805,133 @@ int bpf_jit_add_poke_descriptor(struct bpf_prog *prog, return slot; } +/* + * BPF program pack allocator. + * + * Most BPF programs are pretty small. Allocating a hole page for each + * program is sometime a waste. Many small bpf program also adds pressure + * to instruction TLB. To solve this issue, we introduce a BPF program pack + * allocator. The prog_pack allocator uses HPAGE_PMD_SIZE page (2MB on x86) + * to host BPF programs. + */ +#define BPF_PROG_PACK_SIZE HPAGE_PMD_SIZE +#define BPF_PROG_CHUNK_SHIFT 6 +#define BPF_PROG_CHUNK_SIZE (1 << BPF_PROG_CHUNK_SHIFT) +#define BPF_PROG_CHUNK_MASK (~(BPF_PROG_CHUNK_SIZE - 1)) +#define BPF_PROG_CHUNK_COUNT (BPF_PROG_PACK_SIZE / BPF_PROG_CHUNK_SIZE) + +struct bpf_prog_pack { + struct list_head list; + void *ptr; + unsigned long bitmap[BITS_TO_LONGS(BPF_PROG_CHUNK_COUNT)]; +}; + +#define BPF_PROG_MAX_PACK_PROG_SIZE HPAGE_PMD_SIZE +#define BPF_PROG_SIZE_TO_NBITS(size) (round_up(size, BPF_PROG_CHUNK_SIZE) / BPF_PROG_CHUNK_SIZE) + +static DEFINE_MUTEX(pack_mutex); +static LIST_HEAD(pack_list); + +static struct bpf_prog_pack *alloc_new_pack(void) +{ + struct bpf_prog_pack *pack; + + pack = kzalloc(sizeof(*pack), GFP_KERNEL); + if (!pack) + return NULL; + pack->ptr = module_alloc(BPF_PROG_PACK_SIZE); + if (!pack->ptr) { + kfree(pack); + return NULL; + } + bitmap_zero(pack->bitmap, BPF_PROG_PACK_SIZE / BPF_PROG_CHUNK_SIZE); + list_add_tail(&pack->list, &pack_list); + + set_vm_flush_reset_perms(pack->ptr); + set_memory_ro((unsigned long)pack->ptr, BPF_PROG_PACK_SIZE / PAGE_SIZE); + set_memory_x((unsigned long)pack->ptr, BPF_PROG_PACK_SIZE / PAGE_SIZE); + return pack; +} + +static void *bpf_prog_pack_alloc(u32 size) +{ + unsigned int nbits = BPF_PROG_SIZE_TO_NBITS(size); + struct bpf_prog_pack *pack; + unsigned long pos; + void *ptr = NULL; + + if (size > BPF_PROG_MAX_PACK_PROG_SIZE) { + size = round_up(size, PAGE_SIZE); + ptr = module_alloc(size); + if (ptr) { + set_vm_flush_reset_perms(ptr); + set_memory_ro((unsigned long)ptr, size / PAGE_SIZE); + set_memory_x((unsigned long)ptr, size / PAGE_SIZE); + } + return ptr; + } + mutex_lock(&pack_mutex); + list_for_each_entry(pack, &pack_list, list) { + pos = bitmap_find_next_zero_area(pack->bitmap, BPF_PROG_CHUNK_COUNT, 0, + nbits, 0); + if (pos < BPF_PROG_CHUNK_COUNT) + goto found_free_area; + } + + pack = alloc_new_pack(); + if (!pack) + goto out; + + pos = 0; + +found_free_area: + bitmap_set(pack->bitmap, pos, nbits); + ptr = (void *)(pack->ptr) + (pos << BPF_PROG_CHUNK_SHIFT); + +out: + mutex_unlock(&pack_mutex); + return ptr; +} + +static void bpf_prog_pack_free(struct bpf_binary_header *hdr) +{ + struct bpf_prog_pack *pack = NULL, *tmp; + unsigned int nbits; + unsigned long pos; + void *pack_ptr; + + if (hdr->size > BPF_PROG_MAX_PACK_PROG_SIZE) { + module_memfree(hdr); + return; + } + + pack_ptr = (void *)((unsigned long)hdr & ~(BPF_PROG_PACK_SIZE - 1)); + mutex_lock(&pack_mutex); + + list_for_each_entry(tmp, &pack_list, list) { + if (tmp->ptr == pack_ptr) { + pack = tmp; + break; + } + } + + if (WARN_ONCE(!pack, "bpf_prog_pack bug\n")) + goto out; + + nbits = BPF_PROG_SIZE_TO_NBITS(hdr->size); + pos = ((unsigned long)hdr - (unsigned long)pack_ptr) >> BPF_PROG_CHUNK_SHIFT; + + bitmap_clear(pack->bitmap, pos, nbits); + if (bitmap_find_next_zero_area(pack->bitmap, BPF_PROG_CHUNK_COUNT, 0, + BPF_PROG_CHUNK_COUNT, 0) == 0) { + list_del(&pack->list); + module_memfree(pack->ptr); + kfree(pack); + } +out: + mutex_unlock(&pack_mutex); +} + static atomic_long_t bpf_jit_current; /* Can be overridden by an arch's JIT compiler if it has a custom,