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 208C8C4332F for ; Wed, 11 May 2022 03:18:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241647AbiEKDSR (ORCPT ); Tue, 10 May 2022 23:18:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50348 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241648AbiEKDSP (ORCPT ); Tue, 10 May 2022 23:18:15 -0400 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2AB544B874; Tue, 10 May 2022 20:18:14 -0700 (PDT) Received: from kwepemi500013.china.huawei.com (unknown [172.30.72.56]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4Kyg7w6SPZzhZ4Q; Wed, 11 May 2022 11:17:32 +0800 (CST) Received: from [10.67.111.192] (10.67.111.192) by kwepemi500013.china.huawei.com (7.221.188.120) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Wed, 11 May 2022 11:18:10 +0800 Message-ID: Date: Wed, 11 May 2022 11:18:09 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.9.0 Subject: Re: [PATCH bpf-next v3 4/7] bpf, arm64: Impelment bpf_arch_text_poke() for arm64 Content-Language: en-US To: Jakub Sitnicki 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 , Jakub Kicinski , Jesper Dangaard Brouer , Mark Rutland , Pasha Tatashin , Ard Biesheuvel , Daniel Kiss , Steven Price , Sudeep Holla , Marc Zyngier , Peter Collingbourne , Mark Brown , Delyan Kratunov , Kumar Kartikeya Dwivedi References: <20220424154028.1698685-1-xukuohai@huawei.com> <20220424154028.1698685-5-xukuohai@huawei.com> <87ee11obih.fsf@cloudflare.com> From: Xu Kuohai In-Reply-To: <87ee11obih.fsf@cloudflare.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.67.111.192] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To kwepemi500013.china.huawei.com (7.221.188.120) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 5/10/2022 7:45 PM, Jakub Sitnicki wrote: > On Sun, Apr 24, 2022 at 11:40 AM -04, 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 | 63 +++++++++++++++++++++++++++++++++++ >> 1 file changed, 63 insertions(+) >> >> diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c >> index 8ab4035dea27..3f9bdfec54c4 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 +1531,64 @@ 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; >> + >> + if (!is_bpf_text_address((long)ip)) >> + /* Only poking bpf text is supported. Since kernel function >> + * entry is set up by ftrace, we reply on ftrace to poke kernel >> + * functions. For kernel funcitons, bpf_arch_text_poke() is only > > Nit: s/funcitons/functions/ > >> + * called after a failed poke with ftrace. In this case, there >> + * is probably something wrong with fentry, so there is nothing >> + * we can do here. See register_fentry, unregister_fentry and >> + * modify_fentry for details. >> + */ >> + return -EINVAL; >> + >> + 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); > > Nit: No need for the explicit cast to void *. Type already matches. > >> +out: >> + mutex_unlock(&text_mutex); >> + return ret; >> +} > > . will fix in v4, thanks!