From mboxrd@z Thu Jan 1 00:00:00 1970 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 9D243C433FE for ; Fri, 15 Apr 2022 02:34:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244344AbiDOChT (ORCPT ); Thu, 14 Apr 2022 22:37:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50604 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232664AbiDOChS (ORCPT ); Thu, 14 Apr 2022 22:37:18 -0400 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 565303B283; Thu, 14 Apr 2022 19:34:51 -0700 (PDT) Received: from dggpeml500025.china.huawei.com (unknown [172.30.72.57]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4KfgNV5DVczgYnH; Fri, 15 Apr 2022 10:32:58 +0800 (CST) Received: from [10.174.176.117] (10.174.176.117) by dggpeml500025.china.huawei.com (7.185.36.35) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Fri, 15 Apr 2022 10:34:48 +0800 Subject: Re: [PATCH bpf-next v2 4/6] bpf, arm64: Impelment bpf_arch_text_poke() for arm64 To: Xu Kuohai , , , , , CC: Catalin Marinas , Will Deacon , Steven Rostedt , Ingo Molnar , Daniel Borkmann , Alexei Starovoitov , Zi Shen Lim , Andrii Nakryiko , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , "David S . Miller" , Hideaki YOSHIFUJI , David Ahern , Thomas Gleixner , Borislav Petkov , Dave Hansen , , , Shuah Khan , Mark Rutland , Ard Biesheuvel , Pasha Tatashin , Peter Collingbourne , Daniel Kiss , Sudeep Holla , Steven Price , Marc Zyngier , Mark Brown , Kumar Kartikeya Dwivedi , Delyan Kratunov References: <20220414162220.1985095-1-xukuohai@huawei.com> <20220414162220.1985095-5-xukuohai@huawei.com> From: Hou Tao Message-ID: Date: Fri, 15 Apr 2022 10:34:47 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: <20220414162220.1985095-5-xukuohai@huawei.com> Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Content-Language: en-US X-Originating-IP: [10.174.176.117] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To dggpeml500025.china.huawei.com (7.185.36.35) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Hi, On 4/15/2022 12:22 AM, Xu Kuohai wrote: > Impelment bpf_arch_text_poke() for arm64, so bpf trampoline code can use > it to replace nop with jump, or replace jump with nop. > > Signed-off-by: Xu Kuohai > Acked-by: Song Liu > --- > arch/arm64/net/bpf_jit_comp.c | 52 +++++++++++++++++++++++++++++++++++ > 1 file changed, 52 insertions(+) > > diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c > index 8ab4035dea27..1a1c3ea75ee2 100644 > --- a/arch/arm64/net/bpf_jit_comp.c > +++ b/arch/arm64/net/bpf_jit_comp.c > @@ -9,6 +9,7 @@ > > #include > #include > +#include > #include > #include > #include > @@ -18,6 +19,7 @@ > #include > #include > #include > +#include > #include > > #include "bpf_jit.h" > @@ -1529,3 +1531,53 @@ void bpf_jit_free_exec(void *addr) > { > return vfree(addr); > } > + > +static int gen_branch_or_nop(enum aarch64_insn_branch_type type, void *ip, > + void *addr, u32 *insn) > +{ > + if (!addr) > + *insn = aarch64_insn_gen_nop(); > + else > + *insn = aarch64_insn_gen_branch_imm((unsigned long)ip, > + (unsigned long)addr, > + type); > + > + return *insn != AARCH64_BREAK_FAULT ? 0 : -EFAULT; > +} > + > +int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type poke_type, > + void *old_addr, void *new_addr) > +{ > + int ret; > + u32 old_insn; > + u32 new_insn; > + u32 replaced; > + enum aarch64_insn_branch_type branch_type; > + In bpf_arch_text_poke() of x86, it disables the poking of kernel module, can you explain why it is OK to do so in arm64 ? Because there is no test cases for fentry on linux kernel module, could you please add some tests for it ? > + if (poke_type == BPF_MOD_CALL) > + branch_type = AARCH64_INSN_BRANCH_LINK; > + else > + branch_type = AARCH64_INSN_BRANCH_NOLINK; > + > + if (gen_branch_or_nop(branch_type, ip, old_addr, &old_insn) < 0) > + return -EFAULT; > + > + if (gen_branch_or_nop(branch_type, ip, new_addr, &new_insn) < 0) > + return -EFAULT; > + > + mutex_lock(&text_mutex); > + if (aarch64_insn_read(ip, &replaced)) { > + ret = -EFAULT; > + goto out; > + } > + > + if (replaced != old_insn) { > + ret = -EFAULT; > + goto out; > + } > + > + ret = aarch64_insn_patch_text_nosync((void *)ip, new_insn); > +out: > + mutex_unlock(&text_mutex); > + return ret; > +}