From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-172.mta0.migadu.com (out-172.mta0.migadu.com [91.218.175.172]) (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 D243B28FA; Tue, 21 May 2024 02:12:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716257558; cv=none; b=PBQVSWgSz4NDABbcoDEjjMtaEPtPSmY87kkpOX0cC47w5ZOOhs3mTJtwM+WRAbmTCDPcyqthzMX2ykYuusDdv2pVLiYkNFdaSX0munexOQgpV7ZK77avP0jJIOcIBA50RIV7a6g1lpKPg2QjtCsIV1Yjr22IjKfZLnCFRmWi4+0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716257558; c=relaxed/simple; bh=V2BJLb8tR3YwIBkh3sbUIQ7yeb/oFg50OLQMB4UoXGk=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=c98lhMSzvtDxXZIHTp4+ALLTWDWFXxf8iqXDx7CVcrk5/lA5qRHTUuuhB657qI0Saj26kN0jPiJDXrsMbOWWUjaNDWNdOt0wEK6L7UpOMh8iNdnFjUdGsasyde5oUSY34WHlPH5C3DMFXogqo6Zxvt9G0AskWl19BjUHdB9j6xA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=YW1nCIu3; arc=none smtp.client-ip=91.218.175.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="YW1nCIu3" X-Envelope-To: ivan@cloudflare.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1716257554; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=KeOR0nXKja+YsNuSzWYUqCWPqH9qbcgn9VPIxCYo4x4=; b=YW1nCIu3jqV8jP3fq+3aOh5dqPFcuG0jCJy2RfbwgG/fdcpU5GTQ8g1jZmmCXjTGYd8kF9 dnQMrz816HHVvosxFpzt1wGJebJcK0Qx6B9fIUhoRQg/0+/jlmJI1ajmfX/3Oi+TvblwIW ryWDozoo9WKcR3q35kVToyF5OpYTXZQ= X-Envelope-To: bpf@vger.kernel.org X-Envelope-To: linux-kernel@vger.kernel.org X-Envelope-To: kernel-team@cloudflare.com X-Envelope-To: quentin@isovalent.com X-Envelope-To: ast@kernel.org X-Envelope-To: daniel@iogearbox.net X-Envelope-To: andrii@kernel.org X-Envelope-To: martin.lau@linux.dev X-Envelope-To: song@kernel.org X-Envelope-To: john.fastabend@gmail.com X-Envelope-To: kpsingh@kernel.org X-Envelope-To: sdf@google.com X-Envelope-To: haoluo@google.com X-Envelope-To: jolsa@kernel.org X-Envelope-To: nathan@kernel.org X-Envelope-To: ndesaulniers@google.com X-Envelope-To: trix@redhat.com X-Envelope-To: ramasha@fb.com Message-ID: <92c38851-5435-4562-9dbc-4270d67af0bc@linux.dev> Date: Mon, 20 May 2024 19:12:26 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH] bpftool: un-const bpf_func_info to fix it for llvm 17 and newer Content-Language: en-GB To: Ivan Babrou , bpf@vger.kernel.org Cc: linux-kernel@vger.kernel.org, kernel-team@cloudflare.com, Quentin Monnet , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Song Liu , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , Nathan Chancellor , Nick Desaulniers , Tom Rix , Raman Shukhau References: <20240520225149.5517-1-ivan@cloudflare.com> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Yonghong Song In-Reply-To: <20240520225149.5517-1-ivan@cloudflare.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT On 5/20/24 4:51 PM, Ivan Babrou wrote: > LLVM 17 started treating const structs as constants: > > * https://github.com/llvm/llvm-project/commit/0b2d5b967d98 > > Combined with pointer laundering via ptr_to_u64, which takes a const ptr, > but in reality treats the underlying memory as mutable, this makes clang > always pass zero to btf__type_by_id, which breaks full name resolution. > > Disassembly before (LLVM 16) and after (LLVM 17): > > - 8b 75 cc mov -0x34(%rbp),%esi > - e8 47 8d 02 00 call 3f5b0 > + 31 f6 xor %esi,%esi > + e8 a9 8c 02 00 call 3f510 > > It's a bigger project to fix this properly (and a question whether LLVM > itself should detect this), but for right now let's just fix bpftool. > > For more information, see this thread in bpf mailing list: > > * https://lore.kernel.org/bpf/CABWYdi0ymezpYsQsPv7qzpx2fWuTkoD1-wG1eT-9x-TSREFrQg@mail.gmail.com/T/ > > Fixes: b662000aff84 ("bpftool: Adding support for BTF program names") > Signed-off-by: Ivan Babrou Acked-by: Yonghong Song