From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.loongson.cn (mail.loongson.cn [114.242.206.163]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 9CD87233149; Wed, 1 Jul 2026 01:26:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=114.242.206.163 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782869186; cv=none; b=IU7HHqDTtg8HUdg7EXQTdmhUxPj7tcmthgjzoVxf0tCQZ2o0e2RGtzuxHNEH3E3gEWwZPstq170PGN9zeWhgQaiugSQCRjhm62WyIHsOoaAAwd0q8qP+om3PxeTzaRgut0IkUtqN69daVi8vBkq4DTaJILvC287CXTK7DFqHBI4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782869186; c=relaxed/simple; bh=vOZvYU0esS1V5wkbMA84p3qKEBj4oZEgoABvRH4fKiM=; h=Subject:To:Cc:References:From:Message-ID:Date:MIME-Version: In-Reply-To:Content-Type; b=Pyq6HJ88ScE5W1DirjUQ8yY36jp63MjkEj5rUctDw6kq6M6EgTSdJBbSgafyRsz5VrxSIXMy3ywPK7UK9pLUd+gSIUgU8DHwxzgZ75EH7ttyXobpSAHH2kDzQbolpkOJyRYpBdqPVJFoprz0TzPnN1i9hxyLW5XfPLyXLLtLvL0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=loongson.cn; spf=pass smtp.mailfrom=loongson.cn; arc=none smtp.client-ip=114.242.206.163 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=loongson.cn Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=loongson.cn Received: from loongson.cn (unknown [113.200.148.30]) by gateway (Coremail) with SMTP id _____8Ax+fC5bERqjUwAAA--.1871S3; Wed, 01 Jul 2026 09:26:17 +0800 (CST) Received: from [10.130.40.83] (unknown [113.200.148.30]) by front1 (Coremail) with SMTP id qMiowJCxHOGybERqHcq5AA--.24623S3; Wed, 01 Jul 2026 09:26:11 +0800 (CST) Subject: Re: [RFC PATCH bpf 1/6] bpf: Disallow interpreter fallback for user BPF_ADDR_SPACE_CAST insn To: Leon Hwang , KaFai Wan , bpf@vger.kernel.org Cc: Alexei Starovoitov , Daniel Borkmann , John Fastabend , Andrii Nakryiko , Eduard Zingerman , Kumar Kartikeya Dwivedi , Martin KaFai Lau , Song Liu , Yonghong Song , Jiri Olsa , Emil Tsalapatis , Andrew Morton , Shuah Khan , Puranjay Mohan , Anton Protopopov , linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org References: <20260626154330.33619-1-leon.hwang@linux.dev> <20260626154330.33619-2-leon.hwang@linux.dev> From: Tiezhu Yang Message-ID: Date: Wed, 1 Jul 2026 09:26:10 +0800 User-Agent: Mozilla/5.0 (X11; Linux loongarch64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-CM-TRANSID:qMiowJCxHOGybERqHcq5AA--.24623S3 X-CM-SenderInfo: p1dqw3xlh2x3gn0dqz5rrqw2lrqou0/ X-Coremail-Antispam: 1Uk129KBj93XoW7AFW5tFWkAr18JFyrWFyDurX_yoW8WF4xpF 4rAFyjkF4UXws7W347Kw1Y93W5t3y5W3y7G393Ga4FkFsIqrn3GF1jgrs09rs0kw4xCF12 yr4avFW5CFyrKwcCm3ZEXasCq-sJn29KB7ZKAUJUUUUx529EdanIXcx71UUUUU7KY7ZEXa sCq-sGcSsGvfJ3Ic02F40EFcxC0VAKzVAqx4xG6I80ebIjqfuFe4nvWSU5nxnvy29KBjDU 0xBIdaVrnRJUUUPFb4IE77IF4wAFF20E14v26r1j6r4UM7CY07I20VC2zVCF04k26cxKx2 IYs7xG6rWj6s0DM7CIcVAFz4kK6r1Y6r17M28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48v e4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_Gr0_Xr1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI 0_Gr0_Cr1l84ACjcxK6I8E87Iv67AKxVW8JVWxJwA2z4x0Y4vEx4A2jsIEc7CjxVAFwI0_ Gr0_Gr1UM2kKe7AKxVWUAVWUtwAS0I0E0xvYzxvE52x082IY62kv0487Mc804VCY07AIYI kI8VC2zVCFFI0UMc02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0I7IYx2IY67AKxVWUAVWU twAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFVCjc4AY6r1j6r4UM4x0Y48IcVAKI48JMx k0xIA0c2IEe2xFo4CEbIxvr21lc7CjxVAaw2AFwI0_Jw0_GFyl42xK82IYc2Ij64vIr41l 4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1l4IxYO2xFxVAFwI0_JF0_Jw1lx2IqxVAqx4xG67AKxV WUJVWUGwC20s026x8GjcxK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r4a6rW5MIIYrxkI 7VAKI48JMIIF0xvE2Ix0cI8IcVAFwI0_JFI_Gr1lIxAIcVC0I7IYx2IY6xkF7I0E14v26r 4j6F4UMIIF0xvE42xK8VAvwI8IcIk0rVWUJVWUCwCI42IY6I8E87Iv67AKxVWUJVW8JwCI 42IY6I8E87Iv6xkF7I0E14v26r4j6r4UJbIYCTnIWIevJa73UjIFyTuYvjxU2-VyUUUUU On 2026/6/30 下午10:36, Leon Hwang wrote: > On 2026/6/30 22:29, KaFai Wan wrote: >> On Fri, 2026-06-26 at 23:43 +0800, Leon Hwang wrote: > [...] >>>  /* Fix up helper call offsets on JIT fallback path. */ >>> -static void bpf_fixup_fallback_helpers(struct bpf_verifier_env *env, struct bpf_prog *fp) >>> +static int bpf_fixup_fallback_helpers(struct bpf_verifier_env *env, struct bpf_prog *fp) >>>  { >>>   struct bpf_insn *insn = fp->insnsi; >>>   const struct bpf_func_proto *fn; >>>   int i; >>> >>> - if (!env || !env->ops->get_func_proto) >>> - return; >>> + if (!env) >>> + return 0; >>> >>>   for (i = 0; i < fp->len; i++, insn++) { >>> - if (bpf_helper_call(insn) && bpf_jit_inlines_helper_call(insn->imm)) { >>> + if (env->ops->get_func_proto && bpf_helper_call(insn) && >>> +     bpf_jit_inlines_helper_call(insn->imm)) { >>>   fn = env->ops->get_func_proto(insn->imm, env->prog); >>>   if (fn && fn->func) >>>   insn->imm = fn->func - __bpf_call_base; >> It might be better to use the BPF_CALL_IMM macro. insn->imm = BPF_CALL_IMM(fn->func); > > > Makes sense. > > This might be applied to Tiezhu's patch. Hi all, Alexei said in another thread like this: ``` > [3] https://lore.kernel.org/bpf/20260615025316.24429-1-yangtiezhu@loongson.cn/ I don't think we need such fallback in patch [3]. ``` https://lore.kernel.org/bpf/DJMRIZ5PDWP4.12OOZ8H881H6O@gmail.com/ Should I just drop my previous patch? To be honest, I'm not sure how to solve the issue mentioned in it. Is that a real problem, and does it need to be fixed? What is the next step? Thanks, Tiezhu