From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm1-f65.google.com ([209.85.128.65]:50523 "EHLO mail-wm1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726197AbfEFWBJ (ORCPT ); Mon, 6 May 2019 18:01:09 -0400 Received: by mail-wm1-f65.google.com with SMTP id p21so17666336wmc.0 for ; Mon, 06 May 2019 15:01:07 -0700 (PDT) References: <673b885183fb64f1cbb3ed2387524077@natalenko.name> From: Jiong Wang Subject: Re: [oss-drivers] netronome/nfp/bpf/jit.c cannot be build with -O3 In-reply-to: <673b885183fb64f1cbb3ed2387524077@natalenko.name> Date: Mon, 06 May 2019 23:01:03 +0100 Message-ID: <87mujzutsw.fsf@netronome.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Sender: xdp-newbies-owner@vger.kernel.org List-ID: To: Oleksandr Natalenko Cc: Jakub Kicinski , "David S. Miller" , Alexei Starovoitov , Daniel Borkmann , Martin KaFai Lau , Song Liu , Yonghong Song , Jesper Dangaard Brouer , John Fastabend , netdev@vger.kernel.org, bpf@vger.kernel.org, oss-drivers@netronome.com, linux-kernel@vger.kernel.org, xdp-newbies@vger.kernel.org, valdis@vt.edu 'Oleksandr Natalenko' via OSS Drivers writes: > Hi. > > Obligatory disclaimer: building the kernel with -O3 is a non-standard > thing done via this patch [1], but I've asked people in #kernelnewbies, > and it was suggested that the issue should be still investigated. > > So, with v5.1 kernel release I cannot build the kernel with -O3 anymore. > It fails as shown below: I guess it's because constant prop. Could you try the following change to __emit_shift? drivers/net/ethernet/netronome/nfp/bpf/jit.c __emit_shift:331 - if (sc == SHF_SC_L_SHF) + if (sc == SHF_SC_L_SHF && shift) shift = 32 - shift; emit_shf_indir is passing "0" as shift to __emit_shift which will eventually be turned into 32 and it was OK because we truncate to 5-bit, but before truncation, it will overflow the shift mask. Regards, Jiong > > === > CC drivers/net/ethernet/netronome/nfp/bpf/jit.o > In file included from ./include/asm-generic/bug.h:5, > from ./arch/x86/include/asm/bug.h:83, > from ./include/linux/bug.h:5, > from drivers/net/ethernet/netronome/nfp/bpf/jit.c:6: > In function ‘__emit_shf’, > inlined from ‘emit_shf.constprop’ at > drivers/net/ethernet/netronome/nfp/bpf/jit.c:364:2, > inlined from ‘shl_reg64_lt32_low’ at > drivers/net/ethernet/netronome/nfp/bpf/jit.c:379:2, > inlined from ‘shl_reg’ at > drivers/net/ethernet/netronome/nfp/bpf/jit.c:2506:2: > ./include/linux/compiler.h:344:38: error: call to > ‘__compiletime_assert_341’ declared with attribute error: BUILD_BUG_ON > failed: (((0x001f0000000ULL) + (1ULL << > (__builtin_ffsll(0x001f0000000ULL) - 1))) & (((0x001f0000000ULL) + (1ULL > << (__builtin_ffsll(0x001f0000000ULL) - 1))) - 1)) != 0 > _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__) > ^ > ./include/linux/compiler.h:325:4: note: in definition of macro > ‘__compiletime_assert’ > prefix ## suffix(); \ > ^~~~~~ > ./include/linux/compiler.h:344:2: note: in expansion of macro > ‘_compiletime_assert’ > _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__) > ^~~~~~~~~~~~~~~~~~~ > ./include/linux/build_bug.h:39:37: note: in expansion of macro > ‘compiletime_assert’ > #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg) > ^~~~~~~~~~~~~~~~~~ > ./include/linux/bitfield.h:57:3: note: in expansion of macro > ‘BUILD_BUG_ON_MSG’ > BUILD_BUG_ON_MSG(__builtin_constant_p(_val) ? \ > ^~~~~~~~~~~~~~~~ > ./include/linux/bitfield.h:89:3: note: in expansion of macro > ‘__BF_FIELD_CHECK’ > __BF_FIELD_CHECK(_mask, 0ULL, _val, "FIELD_PREP: "); \ > ^~~~~~~~~~~~~~~~ > drivers/net/ethernet/netronome/nfp/bpf/jit.c:341:3: note: in expansion > of macro ‘FIELD_PREP’ > FIELD_PREP(OP_SHF_SHIFT, shift) | > ^~~~~~~~~~ > make[1]: *** [scripts/Makefile.build:276: > drivers/net/ethernet/netronome/nfp/bpf/jit.o] Error 1 > make: *** [Makefile:1726: drivers/net/ethernet/netronome/nfp/bpf/jit.o] > Error 2 > === > > Needless to say, with -O2 this file is built just fine. My compiler is: > > === > $ gcc --version > gcc (GCC) 8.3.0 > Copyright (C) 2018 Free Software Foundation, Inc. > This is free software; see the source for copying conditions. There is > NO > warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR > PURPOSE. > === > > I had no issues with -O3 before, so, maybe, this deserves a peek. > > I'm open to testing patches and providing more info if needed. > > Thanks. > > [1] > https://gitlab.com/post-factum/pf-kernel/commit/7fef93015ff1776d08119ef3d057a9e9433954a9