Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753415AbdHKQrL (ORCPT ); Fri, 11 Aug 2017 12:47:11 -0400 Received: from www62.your-server.de ([213.133.104.62]:43645 "EHLO www62.your-server.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752901AbdHKQrK (ORCPT ); Fri, 11 Aug 2017 12:47:10 -0400 Message-ID: <598DDF88.6020809@iogearbox.net> Date: Fri, 11 Aug 2017 18:47:04 +0200 From: Daniel Borkmann User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: James Hogan , David Miller CC: ast@kernel.org, linux-kernel@vger.kernel.org, rostedt@goodmis.org, mingo@redhat.com, netdev@vger.kernel.org Subject: Re: [RFC PATCH 2/2] bpf: Initialise mod[] in bpf_trace_printk References: <59897A7C.10009@iogearbox.net> <20170808.094857.245786887664041622.davem@davemloft.net> <650EB3B0-1101-4624-905A-E68D2EC5920F@imgtec.com> <20170808.145433.1287676484744976417.davem@davemloft.net> <20170809073926.GO6973@jhogan-linux.le.imgtec.org> <598B71C9.7090303@iogearbox.net> In-Reply-To: <598B71C9.7090303@iogearbox.net> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-Authenticated-Sender: daniel@iogearbox.net Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2799 Lines: 74 Hi James, On 08/09/2017 10:34 PM, Daniel Borkmann wrote: > On 08/09/2017 09:39 AM, James Hogan wrote: > [...] >> time (but please consider looking at the other patch which is certainly >> a more real issue). > > Sorry for the delay, started looking into that and whether we > have some other options, I'll get back to you on this. Could we solve this more generically (as in: originally intended) in the sense that we don't need to trust the gcc va_list handling; I feel this is relying on an implementation detail? Perhaps something like below poc patch? Thanks again, Daniel From 71f16544d455abb6bb82f7253c17c14d2a395e91 Mon Sep 17 00:00:00 2001 Message-Id: <71f16544d455abb6bb82f7253c17c14d2a395e91.1502469361.git.daniel@iogearbox.net> From: Daniel Borkmann Date: Fri, 11 Aug 2017 15:56:32 +0200 Subject: [PATCH] bpf: fix bpf_trace_printk on 32 bit Signed-off-by: Daniel Borkmann --- kernel/trace/bpf_trace.c | 31 +++++++++++++++++++++++++++---- 1 file changed, 27 insertions(+), 4 deletions(-) diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 3738519..d4cb36f 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -204,10 +204,33 @@ static const struct bpf_func_proto *bpf_get_probe_write_proto(void) fmt_cnt++; } - return __trace_printk(1/* fake ip will not be printed */, fmt, - mod[0] == 2 ? arg1 : mod[0] == 1 ? (long) arg1 : (u32) arg1, - mod[1] == 2 ? arg2 : mod[1] == 1 ? (long) arg2 : (u32) arg2, - mod[2] == 2 ? arg3 : mod[2] == 1 ? (long) arg3 : (u32) arg3); +#define __BPF_TP_EMIT() __BPF_ARG3_TP() +#define __BPF_TP(...) \ + __trace_printk(1 /* fake ip will not be printed */, \ + fmt, ##__VA_ARGS__) + +#define __BPF_ARG1_TP(...) \ + ((mod[0] == 2 || (mod[0] == 1 && __BITS_PER_LONG == 64)) \ + ? __BPF_TP(arg1, ##__VA_ARGS__) \ + : ((mod[0] == 1 || (mod[0] == 0 && __BITS_PER_LONG == 32)) \ + ? __BPF_TP((long)arg1, ##__VA_ARGS__) \ + : __BPF_TP((u32)arg1, ##__VA_ARGS__))) + +#define __BPF_ARG2_TP(...) \ + ((mod[1] == 2 || (mod[1] == 1 && __BITS_PER_LONG == 64)) \ + ? __BPF_ARG1_TP(arg2, ##__VA_ARGS__) \ + : ((mod[1] == 1 || (mod[1] == 0 && __BITS_PER_LONG == 32)) \ + ? __BPF_ARG1_TP((long)arg2, ##__VA_ARGS__) \ + : __BPF_ARG1_TP((u32)arg2, ##__VA_ARGS__))) + +#define __BPF_ARG3_TP(...) \ + ((mod[2] == 2 || (mod[2] == 1 && __BITS_PER_LONG == 64)) \ + ? __BPF_ARG2_TP(arg3, ##__VA_ARGS__) \ + : ((mod[2] == 1 || (mod[2] == 0 && __BITS_PER_LONG == 32)) \ + ? __BPF_ARG2_TP((long)arg3, ##__VA_ARGS__) \ + : __BPF_ARG2_TP((u32)arg3, ##__VA_ARGS__))) + + return __BPF_TP_EMIT(); } static const struct bpf_func_proto bpf_trace_printk_proto = { -- 1.9.3