From patchwork Wed Jan 19 23:06:18 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Song Liu X-Patchwork-Id: 12717848 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 266CEC433EF for ; Wed, 19 Jan 2022 23:07:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1357648AbiASXHP convert rfc822-to-8bit (ORCPT ); Wed, 19 Jan 2022 18:07:15 -0500 Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:33528 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344277AbiASXHA (ORCPT ); Wed, 19 Jan 2022 18:07:00 -0500 Received: from pps.filterd (m0044010.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.1.2/8.16.1.2) with ESMTP id 20JIs2sm000479 for ; Wed, 19 Jan 2022 15:06:59 -0800 Received: from mail.thefacebook.com ([163.114.132.120]) by mx0a-00082601.pphosted.com (PPS) with ESMTPS id 3dp89yf4kk-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Wed, 19 Jan 2022 15:06:59 -0800 Received: from twshared11487.23.frc3.facebook.com (2620:10d:c085:208::f) 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 15.1.2308.20; Wed, 19 Jan 2022 15:06:49 -0800 Received: by devbig006.ftw2.facebook.com (Postfix, from userid 4523) id 00D6428220D24; Wed, 19 Jan 2022 15:06:34 -0800 (PST) From: Song Liu To: , , CC: , , , , , , Song Liu Subject: [PATCH v4 bpf-next 5/7] x86/alternative: introduce text_poke_copy Date: Wed, 19 Jan 2022 15:06:18 -0800 Message-ID: <20220119230620.3137425-6-song@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220119230620.3137425-1-song@kernel.org> References: <20220119230620.3137425-1-song@kernel.org> MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-ORIG-GUID: zPRGkW00kP3DUFdm3BTpPCQ4gAsPo0Zr X-Proofpoint-GUID: zPRGkW00kP3DUFdm3BTpPCQ4gAsPo0Zr 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=2022-01-19_12,2022-01-19_01,2021-12-02_01 X-Proofpoint-Spam-Details: rule=fb_outbound_notspam policy=fb_outbound score=0 adultscore=0 priorityscore=1501 spamscore=0 suspectscore=0 mlxscore=0 malwarescore=0 bulkscore=0 phishscore=0 lowpriorityscore=0 mlxlogscore=350 impostorscore=0 clxscore=1015 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2110150000 definitions=main-2201190122 X-FB-Internal: deliver Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net This will be used by BPF jit compiler to dump JITed binary to a RX huge page, and thus allow multiple BPF programs sharing the a huge (2MB) page. Signed-off-by: Song Liu --- arch/x86/include/asm/text-patching.h | 1 + arch/x86/kernel/alternative.c | 32 ++++++++++++++++++++++++++++ 2 files changed, 33 insertions(+) diff --git a/arch/x86/include/asm/text-patching.h b/arch/x86/include/asm/text-patching.h index b7421780e4e9..4cc18ba1b75e 100644 --- a/arch/x86/include/asm/text-patching.h +++ b/arch/x86/include/asm/text-patching.h @@ -44,6 +44,7 @@ extern void text_poke_early(void *addr, const void *opcode, size_t len); extern void *text_poke(void *addr, const void *opcode, size_t len); extern void text_poke_sync(void); extern void *text_poke_kgdb(void *addr, const void *opcode, size_t len); +extern void *text_poke_copy(void *addr, const void *opcode, size_t len); extern int poke_int3_handler(struct pt_regs *regs); extern void text_poke_bp(void *addr, const void *opcode, size_t len, const void *emulate); diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index 23fb4d51a5da..903a415c19fa 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -1102,6 +1102,38 @@ void *text_poke_kgdb(void *addr, const void *opcode, size_t len) return __text_poke(addr, opcode, len); } +/** + * text_poke_copy - Copy instructions into (an unused part of) RX memory + * @addr: address to modify + * @opcode: source of the copy + * @len: length to copy, could be more than 2x PAGE_SIZE + * + * Not safe against concurrent execution; useful for JITs to dump + * new code blocks into unused regions of RX memory. Can be used in + * conjunction with synchronize_rcu_tasks() to wait for existing + * execution to quiesce after having made sure no existing functions + * pointers are live. + */ +void *text_poke_copy(void *addr, const void *opcode, size_t len) +{ + unsigned long start = (unsigned long)addr; + size_t patched = 0; + + if (WARN_ON_ONCE(core_kernel_text(start))) + return NULL; + + while (patched < len) { + unsigned long ptr = start + patched; + size_t s; + + s = min_t(size_t, PAGE_SIZE * 2 - offset_in_page(ptr), len - patched); + + __text_poke((void *)ptr, opcode + patched, s); + patched += s; + } + return addr; +} + static void do_sync_core(void *info) { sync_core();