From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Borkmann Subject: Re: [PATCH bpf-next v3 10/10] tools: bpftool: add delimiters to multi-function JITed dumps Date: Wed, 23 May 2018 15:50:33 +0200 Message-ID: <024d9f55-2382-8080-c0c2-e3acfbfb9590@iogearbox.net> References: <88b61b11ebca5b44bad0c34225b6f2383e5983a5.1527008647.git.sandipan@linux.vnet.ibm.com> <20180522125544.541c68c8@cakuba> <2dabfa7f-15b8-236c-7724-33bc3da7e549@iogearbox.net> <7142939b-515e-50ac-bc0b-50444bf9cc97@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Cc: ast@kernel.org, netdev@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, mpe@ellerman.id.au, naveen.n.rao@linux.vnet.ibm.com, Quentin Monnet To: Sandipan Das , Jakub Kicinski Return-path: Received: from www62.your-server.de ([213.133.104.62]:54039 "EHLO www62.your-server.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933070AbeEWNui (ORCPT ); Wed, 23 May 2018 09:50:38 -0400 In-Reply-To: <7142939b-515e-50ac-bc0b-50444bf9cc97@linux.vnet.ibm.com> Content-Language: en-US Sender: netdev-owner@vger.kernel.org List-ID: On 05/23/2018 12:37 PM, Sandipan Das wrote: [...] > Other than that, for powerpc64, there is a problem with the way the > binutils disassembler code (in "opcodes/ppc-dis.c") passes arguments > to the callback fprintf_json(). > > In fprintf_json(), we always expect the va_list elements to resolve > to strings (char *). But for powerpc64, the register or immediate > operands are always passed as integers. So, when the code attempts > to resolve these operands using va_arg(ap, char *), bpftool crashes. > For now, I am using a workaround based on vsnprintf() but this does > not get the semantics correct for memory operands. You can probably > see that for the store instructions in the JSON dump above this. > > Daniel, > > Would it be okay if I send out a fix for this in a different series? I'm fine either way with regards to the fix. Feels like a portability bug in the binutils disassembler? We could probably have a feature test like in test-disassembler-four-args and select a workaround in bpftool based on that outcome. Thanks Sandipan! [1] tools/build/feature/test-disassembler-four-args.c