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 862DFC433EF for ; Mon, 11 Jul 2022 14:16:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229966AbiGKOQK (ORCPT ); Mon, 11 Jul 2022 10:16:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36936 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229578AbiGKOQJ (ORCPT ); Mon, 11 Jul 2022 10:16:09 -0400 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3B9C931347; Mon, 11 Jul 2022 07:16:06 -0700 (PDT) Received: from kwepemi500013.china.huawei.com (unknown [172.30.72.54]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4LhQnK62X3zVfcD; Mon, 11 Jul 2022 22:12:21 +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; Mon, 11 Jul 2022 22:16:01 +0800 Message-ID: <4852eba8-9fd0-6894-934c-ab89c0c7cea9@huawei.com> Date: Mon, 11 Jul 2022 22:16:00 +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 v7 4/4] bpf, arm64: bpf trampoline for arm64 Content-Language: en-US To: Jean-Philippe Brucker CC: , , , , Will Deacon , KP Singh , Mark Rutland , Catalin Marinas , Daniel Borkmann , Alexei Starovoitov , Andrii Nakryiko , Zi Shen Lim , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , "David S . Miller" , Hideaki YOSHIFUJI , David Ahern , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , , "H . Peter Anvin" , Jakub Kicinski , Jesper Dangaard Brouer , Russell King , James Morse , Hou Tao , Jason Wang References: <20220708093032.1832755-1-xukuohai@huawei.com> <20220708093032.1832755-5-xukuohai@huawei.com> From: Xu Kuohai In-Reply-To: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.67.111.192] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) 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 7/11/2022 7:57 PM, Jean-Philippe Brucker wrote: > On Fri, Jul 08, 2022 at 05:30:32AM -0400, Xu Kuohai wrote: >> +static void invoke_bpf_prog(struct jit_ctx *ctx, struct bpf_tramp_link *l, >> + int args_off, int retval_off, int run_ctx_off, >> + bool save_ret) >> +{ >> + u32 *branch; >> + u64 enter_prog; >> + u64 exit_prog; >> + u8 r0 = bpf2a64[BPF_REG_0]; >> + struct bpf_prog *p = l->link.prog; >> + int cookie_off = offsetof(struct bpf_tramp_run_ctx, bpf_cookie); >> + >> + if (p->aux->sleepable) { >> + enter_prog = (u64)__bpf_prog_enter_sleepable; >> + exit_prog = (u64)__bpf_prog_exit_sleepable; >> + } else { >> + enter_prog = (u64)__bpf_prog_enter; >> + exit_prog = (u64)__bpf_prog_exit; >> + } >> + >> + if (l->cookie == 0) { >> + /* if cookie is zero, one instruction is enough to store it */ >> + emit(A64_STR64I(A64_ZR, A64_SP, run_ctx_off + cookie_off), ctx); >> + } else { >> + emit_a64_mov_i64(A64_R(10), l->cookie, ctx); >> + emit(A64_STR64I(A64_R(10), A64_SP, run_ctx_off + cookie_off), >> + ctx); >> + } >> + >> + /* save p to callee saved register x19 to avoid loading p with mov_i64 >> + * each time. >> + */ >> + emit_addr_mov_i64(A64_R(19), (const u64)p, ctx); >> + >> + /* arg1: prog */ >> + emit(A64_MOV(1, A64_R(0), A64_R(19)), ctx); >> + /* arg2: &run_ctx */ >> + emit(A64_ADD_I(1, A64_R(1), A64_SP, run_ctx_off), ctx); >> + >> + emit_call(enter_prog, ctx); >> + >> + /* if (__bpf_prog_enter(prog) == 0) >> + * goto skip_exec_of_prog; >> + */ >> + branch = ctx->image + ctx->idx; >> + emit(A64_NOP, ctx); >> + >> + /* save return value to callee saved register x20 */ >> + emit(A64_MOV(1, A64_R(20), A64_R(0)), ctx); >> + >> + emit(A64_ADD_I(1, A64_R(0), A64_SP, args_off), ctx); >> + if (!p->jited) >> + emit_addr_mov_i64(A64_R(1), (const u64)p->insnsi, ctx); >> + >> + emit_call((const u64)p->bpf_func, ctx); >> + >> + /* store return value, which is held in r0 for JIT and in x0 >> + * for interpreter. >> + */ >> + if (save_ret) >> + emit(A64_STR64I(p->jited ? r0 : A64_R(0), A64_SP, retval_off), >> + ctx); > > This should be only A64_R(0), not r0. r0 happens to equal A64_R(0) when > jitted due to the way build_epilogue() builds the function at the moment, > but we shouldn't rely on that. > looks like I misunderstood something, will change it to: /* store return value, which is held in x0 for interpreter and in * bpf register r0 for JIT, but r0 happens to equal x0 due to the * way build_epilogue() builds the JIT image. */ if (save_ret) emit(A64_STR64I(A64_R(0), A64_SP, retval_off), ctx); > Apart from that, for the series > > Reviewed-by: Jean-Philippe Brucker > > .