From patchwork Fri Jan 21 19:49:25 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Song Liu X-Patchwork-Id: 12720187 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 A1BF4C433EF for ; Fri, 21 Jan 2022 19:50:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233026AbiAUTuE convert rfc822-to-8bit (ORCPT ); Fri, 21 Jan 2022 14:50:04 -0500 Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:18416 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S232508AbiAUTtz (ORCPT ); Fri, 21 Jan 2022 14:49:55 -0500 Received: from pps.filterd (m0001303.ppops.net [127.0.0.1]) by m0001303.ppops.net (8.16.1.2/8.16.1.2) with ESMTP id 20LGFnOO005353 for ; Fri, 21 Jan 2022 11:49:54 -0800 Received: from mail.thefacebook.com ([163.114.132.120]) by m0001303.ppops.net (PPS) with ESMTPS id 3dqhy4nhyt-4 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Fri, 21 Jan 2022 11:49:54 -0800 Received: from twshared18912.14.frc2.facebook.com (2620:10d:c085:108::4) by mail.thefacebook.com (2620:10d:c085:21d::7) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.21; Fri, 21 Jan 2022 11:49:51 -0800 Received: by devbig006.ftw2.facebook.com (Postfix, from userid 4523) id 8D03B284A5F3F; Fri, 21 Jan 2022 11:49:41 -0800 (PST) From: Song Liu To: , , CC: , , , , , , Song Liu Subject: [PATCH v6 bpf-next 6/7] bpf: introduce bpf_prog_pack allocator Date: Fri, 21 Jan 2022 11:49:25 -0800 Message-ID: <20220121194926.1970172-7-song@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220121194926.1970172-1-song@kernel.org> References: <20220121194926.1970172-1-song@kernel.org> MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-ORIG-GUID: ThFIh8DkaqpnLd2exl3briHtR_V0fQ2p X-Proofpoint-GUID: ThFIh8DkaqpnLd2exl3briHtR_V0fQ2p 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=2022-01-21_09,2022-01-21_01,2021-12-02_01 X-Proofpoint-Spam-Details: rule=fb_outbound_notspam policy=fb_outbound score=0 impostorscore=0 spamscore=0 malwarescore=0 adultscore=0 clxscore=1015 mlxlogscore=974 bulkscore=0 phishscore=0 suspectscore=0 lowpriorityscore=0 mlxscore=0 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2201110000 definitions=main-2201210128 X-FB-Internal: deliver Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net From: Song Liu 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 --- include/linux/filter.h | 7 ++ kernel/bpf/core.c | 184 ++++++++++++++++++++++++++++++++++++++++- 2 files changed, 187 insertions(+), 4 deletions(-) diff --git a/include/linux/filter.h b/include/linux/filter.h index 27ea68604c22..a58658442d2e 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -1074,6 +1074,13 @@ void *bpf_jit_alloc_exec(unsigned long size); void bpf_jit_free_exec(void *addr); void bpf_jit_free(struct bpf_prog *fp); +struct bpf_binary_header * +bpf_jit_binary_alloc_pack(unsigned int proglen, u8 **image_r_ptr, + unsigned int alignment, + bpf_jit_fill_hole_t bpf_fill_ill_insns); +void bpf_jit_binary_free_pack(struct bpf_binary_header *hdr); +int bpf_prog_pack_max_size(void); + int bpf_jit_add_poke_descriptor(struct bpf_prog *prog, struct bpf_jit_poke_descriptor *poke); diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index f252d8529b0b..a912818a5205 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -808,6 +808,116 @@ 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_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); + 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; + + 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) +{ + void *pack_ptr = (void *)((unsigned long)hdr & ~(BPF_PROG_PACK_SIZE - 1)); + struct bpf_prog_pack *pack = NULL, *tmp; + unsigned int nbits; + unsigned long pos; + + 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, @@ -860,10 +970,59 @@ void __weak bpf_jit_free_exec(void *addr) module_memfree(addr); } +static struct bpf_binary_header * +__bpf_jit_binary_alloc(unsigned int proglen, u8 **image_ptr, + unsigned int alignment, + bpf_jit_fill_hole_t bpf_fill_ill_insns, + u32 round_up_to) +{ + struct bpf_binary_header *hdr; + u32 size, hole, start; + + WARN_ON_ONCE(!is_power_of_2(alignment) || + alignment > BPF_IMAGE_ALIGNMENT); + + /* Most of BPF filters are really small, but if some of them + * fill a page, allow at least 128 extra bytes to insert a + * random section of illegal instructions. + */ + size = round_up(proglen + sizeof(*hdr) + 128, round_up_to); + + if (bpf_jit_charge_modmem(size)) + return NULL; + hdr = bpf_jit_alloc_exec(size); + if (!hdr) { + bpf_jit_uncharge_modmem(size); + return NULL; + } + + /* Fill space with illegal/arch-dep instructions. */ + bpf_fill_ill_insns(hdr, size); + + hdr->size = size; + hole = min_t(unsigned int, size - (proglen + sizeof(*hdr)), + PAGE_SIZE - sizeof(*hdr)); + start = (get_random_int() % hole) & ~(alignment - 1); + + /* Leave a random number of instructions before BPF code. */ + *image_ptr = &hdr->image[start]; + + return hdr; +} + struct bpf_binary_header * bpf_jit_binary_alloc(unsigned int proglen, u8 **image_ptr, unsigned int alignment, bpf_jit_fill_hole_t bpf_fill_ill_insns) +{ + return __bpf_jit_binary_alloc(proglen, image_ptr, alignment, + bpf_fill_ill_insns, PAGE_SIZE); +} + +struct bpf_binary_header * +bpf_jit_binary_alloc_pack(unsigned int proglen, u8 **image_ptr, + unsigned int alignment, + bpf_jit_fill_hole_t bpf_fill_ill_insns) { struct bpf_binary_header *hdr; u32 size, hole, start; @@ -875,11 +1034,16 @@ bpf_jit_binary_alloc(unsigned int proglen, u8 **image_ptr, * fill a page, allow at least 128 extra bytes to insert a * random section of illegal instructions. */ - size = round_up(proglen + sizeof(*hdr) + 128, PAGE_SIZE); + size = round_up(proglen + sizeof(*hdr) + 128, BPF_PROG_CHUNK_SIZE); + + /* for too big program, use __bpf_jit_binary_alloc. */ + if (size > BPF_PROG_MAX_PACK_PROG_SIZE) + return __bpf_jit_binary_alloc(proglen, image_ptr, alignment, + bpf_fill_ill_insns, PAGE_SIZE); if (bpf_jit_charge_modmem(size)) return NULL; - hdr = bpf_jit_alloc_exec(size); + hdr = bpf_prog_pack_alloc(size); if (!hdr) { bpf_jit_uncharge_modmem(size); return NULL; @@ -888,9 +1052,8 @@ bpf_jit_binary_alloc(unsigned int proglen, u8 **image_ptr, /* Fill space with illegal/arch-dep instructions. */ bpf_fill_ill_insns(hdr, size); - hdr->size = size; hole = min_t(unsigned int, size - (proglen + sizeof(*hdr)), - PAGE_SIZE - sizeof(*hdr)); + BPF_PROG_CHUNK_SIZE - sizeof(*hdr)); start = (get_random_int() % hole) & ~(alignment - 1); /* Leave a random number of instructions before BPF code. */ @@ -907,6 +1070,19 @@ void bpf_jit_binary_free(struct bpf_binary_header *hdr) bpf_jit_uncharge_modmem(size); } +void bpf_jit_binary_free_pack(struct bpf_binary_header *hdr) +{ + u32 size = hdr->size; + + bpf_prog_pack_free(hdr); + bpf_jit_uncharge_modmem(size); +} + +int bpf_prog_pack_max_size(void) +{ + return BPF_PROG_MAX_PACK_PROG_SIZE; +} + /* This symbol is only overridden by archs that have different * requirements than the usual eBPF JITs, f.e. when they only * implement cBPF JIT, do not set images read-only, etc.