From patchwork Fri Sep 23 21:18:36 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Song Liu X-Patchwork-Id: 12987216 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 DFCC2C6FA83 for ; Fri, 23 Sep 2022 21:18:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230001AbiIWVS6 convert rfc822-to-8bit (ORCPT ); Fri, 23 Sep 2022 17:18:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39560 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229495AbiIWVS6 (ORCPT ); Fri, 23 Sep 2022 17:18:58 -0400 Received: from mx0a-00082601.pphosted.com (mx0a-00082601.pphosted.com [67.231.145.42]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 82AF112206C for ; Fri, 23 Sep 2022 14:18:57 -0700 (PDT) Received: from pps.filterd (m0109333.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.17.1.5/8.17.1.5) with ESMTP id 28NIGA0I012506 for ; Fri, 23 Sep 2022 14:18:57 -0700 Received: from maileast.thefacebook.com ([163.114.130.16]) by mx0a-00082601.pphosted.com (PPS) with ESMTPS id 3jsb1nmeh8-7 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Fri, 23 Sep 2022 14:18:57 -0700 Received: from twshared20273.14.frc2.facebook.com (2620:10d:c0a8:1b::d) by mail.thefacebook.com (2620:10d:c0a8:83::4) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Fri, 23 Sep 2022 14:18:53 -0700 Received: by devbig932.frc1.facebook.com (Postfix, from userid 4523) id 5AE63D4BF99F; Fri, 23 Sep 2022 14:18:49 -0700 (PDT) From: Song Liu To: CC: , , , , , , , Song Liu Subject: [PATCH bpf-next 1/2] bpf: use bpf_prog_pack for bpf_dispatcher Date: Fri, 23 Sep 2022 14:18:36 -0700 Message-ID: <20220923211837.3044723-2-song@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220923211837.3044723-1-song@kernel.org> References: <20220923211837.3044723-1-song@kernel.org> MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-ORIG-GUID: 1B836LWFb6HA2DAHYWn1GboiKxMxVNZn X-Proofpoint-GUID: 1B836LWFb6HA2DAHYWn1GboiKxMxVNZn X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.895,Hydra:6.0.528,FMLib:17.11.122.1 definitions=2022-09-23_10,2022-09-22_02,2022-06-22_01 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net Allocate bpf_dispatcher with bpf_prog_pack_alloc so that bpf_dispatcher can share pages with bpf programs. This also fixes CPA W^X warnning like: CPA refuse W^X violation: 8000000000000163 -> 0000000000000163 range: ... Signed-off-by: Song Liu --- include/linux/bpf.h | 1 + include/linux/filter.h | 5 +++++ kernel/bpf/core.c | 9 +++++++-- kernel/bpf/dispatcher.c | 21 ++++++++++++++++++--- 4 files changed, 31 insertions(+), 5 deletions(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index edd43edb27d6..a8d0cfe14372 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -946,6 +946,7 @@ struct bpf_dispatcher { struct bpf_dispatcher_prog progs[BPF_DISPATCHER_MAX]; int num_progs; void *image; + void *rw_image; u32 image_off; struct bpf_ksym ksym; }; diff --git a/include/linux/filter.h b/include/linux/filter.h index 98e28126c24b..efc42a6e3aed 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -1023,6 +1023,8 @@ extern long bpf_jit_limit_max; typedef void (*bpf_jit_fill_hole_t)(void *area, unsigned int size); +void bpf_jit_fill_hole_with_zero(void *area, unsigned int size); + struct bpf_binary_header * bpf_jit_binary_alloc(unsigned int proglen, u8 **image_ptr, unsigned int alignment, @@ -1035,6 +1037,9 @@ void bpf_jit_free(struct bpf_prog *fp); struct bpf_binary_header * bpf_jit_binary_pack_hdr(const struct bpf_prog *fp); +void *bpf_prog_pack_alloc(u32 size, bpf_jit_fill_hole_t bpf_fill_ill_insns); +void bpf_prog_pack_free(struct bpf_binary_header *hdr); + static inline bool bpf_prog_kallsyms_verify_off(const struct bpf_prog *fp) { return list_empty(&fp->aux->ksym.lnode) || diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index d1be78c28619..711fd293b6de 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -825,6 +825,11 @@ struct bpf_prog_pack { unsigned long bitmap[]; }; +void bpf_jit_fill_hole_with_zero(void *area, unsigned int size) +{ + memset(area, 0, size); +} + #define BPF_PROG_SIZE_TO_NBITS(size) (round_up(size, BPF_PROG_CHUNK_SIZE) / BPF_PROG_CHUNK_SIZE) static DEFINE_MUTEX(pack_mutex); @@ -864,7 +869,7 @@ static struct bpf_prog_pack *alloc_new_pack(bpf_jit_fill_hole_t bpf_fill_ill_ins return pack; } -static void *bpf_prog_pack_alloc(u32 size, bpf_jit_fill_hole_t bpf_fill_ill_insns) +void *bpf_prog_pack_alloc(u32 size, bpf_jit_fill_hole_t bpf_fill_ill_insns) { unsigned int nbits = BPF_PROG_SIZE_TO_NBITS(size); struct bpf_prog_pack *pack; @@ -905,7 +910,7 @@ static void *bpf_prog_pack_alloc(u32 size, bpf_jit_fill_hole_t bpf_fill_ill_insn return ptr; } -static void bpf_prog_pack_free(struct bpf_binary_header *hdr) +void bpf_prog_pack_free(struct bpf_binary_header *hdr) { struct bpf_prog_pack *pack = NULL, *tmp; unsigned int nbits; diff --git a/kernel/bpf/dispatcher.c b/kernel/bpf/dispatcher.c index 2444bd15cc2d..8a10300854b6 100644 --- a/kernel/bpf/dispatcher.c +++ b/kernel/bpf/dispatcher.c @@ -104,7 +104,7 @@ static int bpf_dispatcher_prepare(struct bpf_dispatcher *d, void *image) static void bpf_dispatcher_update(struct bpf_dispatcher *d, int prev_num_progs) { - void *old, *new; + void *old, *new, *tmp; u32 noff; int err; @@ -117,8 +117,14 @@ static void bpf_dispatcher_update(struct bpf_dispatcher *d, int prev_num_progs) } new = d->num_progs ? d->image + noff : NULL; + tmp = d->num_progs ? d->rw_image + noff : NULL; if (new) { - if (bpf_dispatcher_prepare(d, new)) + /* Prepare the dispatcher in d->rw_image. Then use + * bpf_arch_text_copy to update d->image, which is RO+X. + */ + if (bpf_dispatcher_prepare(d, tmp)) + return; + if (IS_ERR(bpf_arch_text_copy(new, tmp, PAGE_SIZE / 2))) return; } @@ -140,9 +146,18 @@ void bpf_dispatcher_change_prog(struct bpf_dispatcher *d, struct bpf_prog *from, mutex_lock(&d->mutex); if (!d->image) { - d->image = bpf_jit_alloc_exec_page(); + d->image = bpf_prog_pack_alloc(PAGE_SIZE, bpf_jit_fill_hole_with_zero); if (!d->image) goto out; + d->rw_image = bpf_jit_alloc_exec(PAGE_SIZE); + if (!d->rw_image) { + u32 size = PAGE_SIZE; + + bpf_arch_text_copy(d->image, &size, sizeof(size)); + bpf_prog_pack_free((struct bpf_binary_header *)d->image); + d->image = NULL; + goto out; + } bpf_image_ksym_add(d->image, &d->ksym); }