From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from szxga05-in.huawei.com (szxga05-in.huawei.com [45.249.212.191]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 762842D9EC8; Wed, 20 Aug 2025 10:10:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.191 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755684613; cv=none; b=KOg7QF9WqBaioOVrQnRjwV6AFukhB4P8QRMsCPppMq6fFFqEE3jKdBr0Soz6YXLeJ9UWWhKEblg7zlB0UsUDaungyFNvglRgGEkTkWvzUH/LnqyZZIkre21MicPE0VgXUfE5wKfVvC1U5k0KULvvjz7WiTbZrNk1hv4sm7qgImc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755684613; c=relaxed/simple; bh=3VZJAWVT2ZlOtPTm8k6zpzkymgEDbsaX7suXN3GO5Cg=; h=Message-ID:Date:MIME-Version:Subject:To:CC:References:From: In-Reply-To:Content-Type; b=R7vFQH8voXqQl1drI0tkHFgDA6c1VqK+/c/inkOpuw3MxffNg2HDwuXESFP1M7L1V5ZQzIo7J7tAYKRxyI0NOWFj8uSsDqULCJcpiUN7NYusXlkHcnUerMTva03rI0AGeJIkAVf0anoInTVNfBachHBb0xeF4L+lv0XLqwfwpSI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=45.249.212.191 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.19.88.214]) by szxga05-in.huawei.com (SkyGuard) with ESMTP id 4c6MZD0GyLz2gL95; Wed, 20 Aug 2025 18:07:16 +0800 (CST) Received: from kwepemf100007.china.huawei.com (unknown [7.202.181.221]) by mail.maildlp.com (Postfix) with ESMTPS id 236CE1A0171; Wed, 20 Aug 2025 18:10:09 +0800 (CST) Received: from [10.67.109.184] (10.67.109.184) by kwepemf100007.china.huawei.com (7.202.181.221) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Wed, 20 Aug 2025 18:10:07 +0800 Message-ID: <239193b7-7dab-45b0-ab13-06bfe3f96f22@huawei.com> Date: Wed, 20 Aug 2025 18:10:07 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] riscv: bpf: Fix uninitialized symbol 'retval_off' Content-Language: en-US To: Chenghao Duan CC: , , , , , , , , , , , , , , , , , , , , References: <20250820062520.846720-1-duanchenghao@kylinos.cn> <8b836b6e-103a-41c2-b111-0417d8db4dce@huawei.com> <20250820092628.GA1289807@chenghao-pc> From: Pu Lehui In-Reply-To: <20250820092628.GA1289807@chenghao-pc> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-ClientProxiedBy: kwepems100001.china.huawei.com (7.221.188.238) To kwepemf100007.china.huawei.com (7.202.181.221) On 2025/8/20 17:26, Chenghao Duan wrote: > On Wed, Aug 20, 2025 at 02:52:01PM +0800, Pu Lehui wrote: >> >> >> On 2025/8/20 14:25, Chenghao Duan wrote: >>> In __arch_prepare_bpf_trampoline(), retval_off is only meaningful when >>> save_ret is true, so the current logic is correct. However, in the >> >> lgtm, and same for `ip_off`, pls patch it together. > > I also checked at the time that ip_off is only initialized and assigned > when flags & BPF_TRAMP_F_IP_ARG is true. However, I noticed that the use > of ip_off also requires this condition, so the compiler did not issue a > warning. > > Chenghao > >> >>> original logic, retval_off is only initialized under certain Can you show how to replay this warning? I guess the warning path is as follow. Compiler didn't know fmod_ret prog need BPF_TRAMP_F_CALL_ORIG. ``` if (fmod_ret->nr_links) { ... emit_sd(RV_REG_FP, -retval_off, RV_REG_ZERO, ctx); } ``` >>> conditions, which may cause a build warning. >>> >>> So initialize retval_off unconditionally to fix it. >>> >>> Signed-off-by: Chenghao Duan >>> --- >>> arch/riscv/net/bpf_jit_comp64.c | 5 ++--- >>> 1 file changed, 2 insertions(+), 3 deletions(-) >>> >>> diff --git a/arch/riscv/net/bpf_jit_comp64.c b/arch/riscv/net/bpf_jit_comp64.c >>> index 10e01ff06312..49bbda8372b0 100644 >>> --- a/arch/riscv/net/bpf_jit_comp64.c >>> +++ b/arch/riscv/net/bpf_jit_comp64.c >>> @@ -1079,10 +1079,9 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, >>> stack_size += 16; >>> save_ret = flags & (BPF_TRAMP_F_CALL_ORIG | BPF_TRAMP_F_RET_FENTRY_RET); >>> - if (save_ret) { >>> + if (save_ret) >>> stack_size += 16; /* Save both A5 (BPF R0) and A0 */ >>> - retval_off = stack_size; >>> - } >>> + retval_off = stack_size; >>> stack_size += nr_arg_slots * 8; >>> args_off = stack_size;