From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: linux-next: build failure after merge of the net-next tree Date: Thu, 11 Jan 2018 22:11:45 -0500 (EST) Message-ID: <20180111.221145.643386077098131140.davem@davemloft.net> References: <20180111115355.29c2f905@canb.auug.org.au> <20180111015853.2pmxtqlrsyxelqf6@ast-mbp> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Return-path: Received: from shards.monkeyblade.net ([184.105.139.130]:48606 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932298AbeALDL7 (ORCPT ); Thu, 11 Jan 2018 22:11:59 -0500 In-Reply-To: <20180111015853.2pmxtqlrsyxelqf6@ast-mbp> Sender: linux-next-owner@vger.kernel.org List-ID: To: alexei.starovoitov@gmail.com Cc: sfr@canb.auug.org.au, netdev@vger.kernel.org, daniel@iogearbox.net, ast@kernel.org, linux-next@vger.kernel.org, linux-kernel@vger.kernel.org From: Alexei Starovoitov Date: Wed, 10 Jan 2018 17:58:54 -0800 > On Thu, Jan 11, 2018 at 11:53:55AM +1100, Stephen Rothwell wrote: >> Hi all, >> >> After merging the net-next tree, today's linux-next build (x86_64 >> allmodconfig) failed like this: >> >> kernel/bpf/verifier.o: In function `bpf_check': >> verifier.c:(.text+0xd86e): undefined reference to `bpf_patch_call_args' >> >> Caused by commit >> >> 1ea47e01ad6e ("bpf: add support for bpf_call to interpreter") >> >> interacting with commit >> >> 290af86629b2 ("bpf: introduce BPF_JIT_ALWAYS_ON config") >> >> from the bpf and net trees. >> >> I have just reverted commit 290af86629b2 for today. A better solution >> would be nice (lie fixing this in a merge between the net-next and net >> trees). > > that's due to 'endif' from 290af86629b2 needs to be moved above > bpf_patch_call_args() definition. That doesn't fix it, because then you'd need to expose interpreters_args as well and obviously that can't be right. Instead, we should never call bpf_patch_call_args() when JIT always on is enabled. So if we fail to JIT the subprogs we should fail immediately. This is the net --> net-next merge resolution I am about to use to fix this: ... +static int fixup_call_args(struct bpf_verifier_env *env) +{ + struct bpf_prog *prog = env->prog; + struct bpf_insn *insn = prog->insnsi; - int i, depth; ++ int i, depth, err; + - if (env->prog->jit_requested) - if (jit_subprogs(env) == 0) ++ err = 0; ++ if (env->prog->jit_requested) { ++ err = jit_subprogs(env); ++ if (err == 0) + return 0; - ++ } ++#ifndef CONFIG_BPF_JIT_ALWAYS_ON + for (i = 0; i < prog->len; i++, insn++) { + if (insn->code != (BPF_JMP | BPF_CALL) || + insn->src_reg != BPF_PSEUDO_CALL) + continue; + depth = get_callee_stack_depth(env, insn, i); + if (depth < 0) + return depth; + bpf_patch_call_args(insn, depth); + } - return 0; ++ err = 0; ++#endif ++ return err; +} + /* fixup insn->imm field of bpf_call instructions * and inline eligible helpers as explicit sequence of BPF instructions *