From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D1261C43334 for ; Mon, 6 Jun 2022 21:20:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230342AbiFFVUl (ORCPT ); Mon, 6 Jun 2022 17:20:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40368 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231193AbiFFVUj (ORCPT ); Mon, 6 Jun 2022 17:20:39 -0400 Received: from mail-oa1-x2e.google.com (mail-oa1-x2e.google.com [IPv6:2001:4860:4864:20::2e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D30ABA180; Mon, 6 Jun 2022 14:20:37 -0700 (PDT) Received: by mail-oa1-x2e.google.com with SMTP id 586e51a60fabf-f2e0a41009so20733037fac.6; Mon, 06 Jun 2022 14:20:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=HuxHinGBrJBTK3TTWKqPn9B+ODkbbS/hGNHjx9GIcog=; b=kMa1xkT91B+otL9XYAY5Ftp80mSKxNBhqXVlLmVwxQh/D2QjVBJTQa2j6ahKVSww5H tBhUfvbHw+ZIHPhz6sia28yNt4o+xFkz7OL75a2Th7QzwIRF4ueLITrl2LDsElyIoJxW xqg5M8KsgNyfYqXdOJHqLAPfAF2hhDoQ/WpQi1OQxWcj6gjwNyJiiVwkqj4EjlP6p3KV PqQrbszBCbPdrMWPZctn3boOYJTLPWzMPKrcsybCl5NhZH1kRmOaIfshPhNGl09SVTpD iAc3OLRSBJ4CIIQLZBE3yo9cWvP3ngKc6I0SAgQ5sdur6BcQ7NhJtyfD+PRxp+KU4k/m Vg0w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=HuxHinGBrJBTK3TTWKqPn9B+ODkbbS/hGNHjx9GIcog=; b=VRt0rfoFYQePMJiHP1w/eBCbPGwks7mDZQAn7LbR30ooXnA7oPwBoQ+/caFR7NlWw2 P36F8wIQsRvo9ea+cpP8HT8krRR2JWHaYWfXDLrbI8YDrVrHgyXZ1pU0a+awC37YZHGq Q1doDx71EtFmLAJoToNc0OTgFqScLbjdhmr5TnJQirJli9fujYa4AjCrfA5fxSRGmeZl p698mwX0VI6/AblMnIglz8cUhMuYzuisej2qeVh55QLUr/5Ttrq26110D6mR9ykGNIDf 0CLXfLHmfZ705RaZ5BtljZm3wKSKyP3HuABh2V9aa5m3QS6gxrv6uAdyRrDoHACbjfhb XlJg== X-Gm-Message-State: AOAM530s+Nuc06QSRAg1ZfX80rHtUtHUiZCK50dkokdDZzemTinwgJ3+ fe1iAAEeVkWzSfUE6A5bIFxPKbFXukfSJmXA0326muqz4mM= X-Google-Smtp-Source: ABdhPJycZiOgkgYr6ckkBj/PLYQmTOLBoWRaZbnm03XSyIwTO35GvE2BqOvRcW9UKMyzg6Cf2K03IK4xe25QN4FMhDI= X-Received: by 2002:a05:6870:3105:b0:f2:9615:ff8e with SMTP id v5-20020a056870310500b000f29615ff8emr30161673oaa.200.1654550437084; Mon, 06 Jun 2022 14:20:37 -0700 (PDT) MIME-Version: 1.0 References: <20220606132741.3462925-1-james.hilliard1@gmail.com> In-Reply-To: From: James Hilliard Date: Mon, 6 Jun 2022 15:20:25 -0600 Message-ID: Subject: Re: [PATCH 1/1] libbpf: fix broken gcc pragma macros in bpf_helpers.h/bpf_tracing.h To: Andrii Nakryiko Cc: bpf , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , "open list:BPF (Safe dynamic programs and tools)" , open list Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Mon, Jun 6, 2022 at 12:02 PM Andrii Nakryiko wrote: > > On Mon, Jun 6, 2022 at 6:28 AM James Hilliard wrote: > > > > It seems the gcc preprocessor breaks unless pragmas are wrapped > > individually inside macros. > > > > Fixes errors like: > > error: expected identifier or '(' before '#pragma' > > 106 | SEC("cgroup/bind6") > > | ^~~ > > > > error: expected '=', ',', ';', 'asm' or '__attribute__' before '#pragma' > > 114 | char _license[] SEC("license") = "GPL"; > > | ^~~ > > > > We've been using this macro in this form for a while with no errors. > How do you get these errors in the first place? I was attempting to compile the systemd bpf programs using gcc 12.1. https://github.com/systemd/systemd/tree/main/src/core/bpf > _Pragma is supposed to > be a full equivalent of #pragma specifically to be able to be used in > macros, so these work-arounds shouldn't be necessary. I did try and style this like the nested macro example here: https://gcc.gnu.org/onlinedocs/gcc/Diagnostic-Pragmas.html > Let's first try > to root cause this. I was looking around and it seems there's a bunch of gcc preprocessor pragma issues in general, restyling this seemed to be the best option at the moment since a lot looked to be unfixed: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53431 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=55578 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89718 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91669 > > > Signed-off-by: James Hilliard > > --- > > tools/lib/bpf/bpf_helpers.h | 26 ++++++++++++++------------ > > tools/lib/bpf/bpf_tracing.h | 26 ++++++++++++++------------ > > 2 files changed, 28 insertions(+), 24 deletions(-) > > > > diff --git a/tools/lib/bpf/bpf_helpers.h b/tools/lib/bpf/bpf_helpers.h > > index fb04eaf367f1..6d159082727d 100644 > > --- a/tools/lib/bpf/bpf_helpers.h > > +++ b/tools/lib/bpf/bpf_helpers.h > > @@ -22,11 +22,13 @@ > > * To allow use of SEC() with externs (e.g., for extern .maps declarations), > > * make sure __attribute__((unused)) doesn't trigger compilation warning. > > */ > > +#define __gcc_helpers_pragma(x) _Pragma(#x) > > +#define __gcc_helpers_diag_pragma(x) __gcc_helpers_pragma("GCC diagnostic " #x) > > #define SEC(name) \ > > - _Pragma("GCC diagnostic push") \ > > - _Pragma("GCC diagnostic ignored \"-Wignored-attributes\"") \ > > + __gcc_helpers_diag_pragma(push) \ > > + __gcc_helpers_diag_pragma(ignored "-Wignored-attributes") \ > > __attribute__((section(name), used)) \ > > - _Pragma("GCC diagnostic pop") \ > > + __gcc_helpers_diag_pragma(pop) > > > > /* Avoid 'linux/stddef.h' definition of '__always_inline'. */ > > #undef __always_inline > > @@ -215,10 +217,10 @@ enum libbpf_tristate { > > static const char ___fmt[] = fmt; \ > > unsigned long long ___param[___bpf_narg(args)]; \ > > \ > > - _Pragma("GCC diagnostic push") \ > > - _Pragma("GCC diagnostic ignored \"-Wint-conversion\"") \ > > + __gcc_helpers_diag_pragma(push) \ > > + __gcc_helpers_diag_pragma(ignored "-Wint-conversion") \ > > ___bpf_fill(___param, args); \ > > - _Pragma("GCC diagnostic pop") \ > > + __gcc_helpers_diag_pragma(pop) \ > > \ > > bpf_seq_printf(seq, ___fmt, sizeof(___fmt), \ > > ___param, sizeof(___param)); \ > > @@ -233,10 +235,10 @@ enum libbpf_tristate { > > static const char ___fmt[] = fmt; \ > > unsigned long long ___param[___bpf_narg(args)]; \ > > \ > > - _Pragma("GCC diagnostic push") \ > > - _Pragma("GCC diagnostic ignored \"-Wint-conversion\"") \ > > + __gcc_helpers_diag_pragma(push) \ > > + __gcc_helpers_diag_pragma(ignored "-Wint-conversion") \ > > ___bpf_fill(___param, args); \ > > - _Pragma("GCC diagnostic pop") \ > > + __gcc_helpers_diag_pragma(pop) \ > > \ > > bpf_snprintf(out, out_size, ___fmt, \ > > ___param, sizeof(___param)); \ > > @@ -264,10 +266,10 @@ enum libbpf_tristate { > > static const char ___fmt[] = fmt; \ > > unsigned long long ___param[___bpf_narg(args)]; \ > > \ > > - _Pragma("GCC diagnostic push") \ > > - _Pragma("GCC diagnostic ignored \"-Wint-conversion\"") \ > > + __gcc_helpers_diag_pragma(push) \ > > + __gcc_helpers_diag_pragma(ignored "-Wint-conversion") \ > > ___bpf_fill(___param, args); \ > > - _Pragma("GCC diagnostic pop") \ > > + __gcc_helpers_diag_pragma(pop) \ > > \ > > bpf_trace_vprintk(___fmt, sizeof(___fmt), \ > > ___param, sizeof(___param)); \ > > diff --git a/tools/lib/bpf/bpf_tracing.h b/tools/lib/bpf/bpf_tracing.h > > index 01ce121c302d..e08ffc290b3e 100644 > > --- a/tools/lib/bpf/bpf_tracing.h > > +++ b/tools/lib/bpf/bpf_tracing.h > > @@ -422,16 +422,18 @@ struct pt_regs; > > * This is useful when using BPF helpers that expect original context > > * as one of the parameters (e.g., for bpf_perf_event_output()). > > */ > > +#define __gcc_tracing_pragma(x) _Pragma(#x) > > +#define __gcc_tracing_diag_pragma(x) __gcc_tracing_pragma("GCC diagnostic " #x) > > #define BPF_PROG(name, args...) \ > > name(unsigned long long *ctx); \ > > static __attribute__((always_inline)) typeof(name(0)) \ > > ____##name(unsigned long long *ctx, ##args); \ > > typeof(name(0)) name(unsigned long long *ctx) \ > > { \ > > - _Pragma("GCC diagnostic push") \ > > - _Pragma("GCC diagnostic ignored \"-Wint-conversion\"") \ > > + __gcc_tracing_diag_pragma(push) \ > > + __gcc_tracing_diag_pragma(ignored "-Wint-conversion") \ > > return ____##name(___bpf_ctx_cast(args)); \ > > - _Pragma("GCC diagnostic pop") \ > > + __gcc_tracing_diag_pragma(pop) \ > > } \ > > static __attribute__((always_inline)) typeof(name(0)) \ > > ____##name(unsigned long long *ctx, ##args) > > @@ -462,10 +464,10 @@ static __attribute__((always_inline)) typeof(name(0)) \ > > ____##name(struct pt_regs *ctx, ##args); \ > > typeof(name(0)) name(struct pt_regs *ctx) \ > > { \ > > - _Pragma("GCC diagnostic push") \ > > - _Pragma("GCC diagnostic ignored \"-Wint-conversion\"") \ > > + __gcc_tracing_diag_pragma(push) \ > > + __gcc_tracing_diag_pragma(ignored "-Wint-conversion") \ > > return ____##name(___bpf_kprobe_args(args)); \ > > - _Pragma("GCC diagnostic pop") \ > > + __gcc_tracing_diag_pragma(pop) \ > > } \ > > static __attribute__((always_inline)) typeof(name(0)) \ > > ____##name(struct pt_regs *ctx, ##args) > > @@ -486,10 +488,10 @@ static __attribute__((always_inline)) typeof(name(0)) \ > > ____##name(struct pt_regs *ctx, ##args); \ > > typeof(name(0)) name(struct pt_regs *ctx) \ > > { \ > > - _Pragma("GCC diagnostic push") \ > > - _Pragma("GCC diagnostic ignored \"-Wint-conversion\"") \ > > + __gcc_tracing_diag_pragma(push) \ > > + __gcc_tracing_diag_pragma(ignored "-Wint-conversion") \ > > return ____##name(___bpf_kretprobe_args(args)); \ > > - _Pragma("GCC diagnostic pop") \ > > + __gcc_tracing_diag_pragma(pop) \ > > } \ > > static __always_inline typeof(name(0)) ____##name(struct pt_regs *ctx, ##args) > > > > @@ -520,10 +522,10 @@ ____##name(struct pt_regs *ctx, ##args); \ > > typeof(name(0)) name(struct pt_regs *ctx) \ > > { \ > > struct pt_regs *regs = PT_REGS_SYSCALL_REGS(ctx); \ > > - _Pragma("GCC diagnostic push") \ > > - _Pragma("GCC diagnostic ignored \"-Wint-conversion\"") \ > > + __gcc_tracing_diag_pragma(push) \ > > + __gcc_tracing_diag_pragma(ignored "-Wint-conversion") \ > > return ____##name(___bpf_syscall_args(args)); \ > > - _Pragma("GCC diagnostic pop") \ > > + __gcc_tracing_diag_pragma(pop) \ > > } \ > > static __attribute__((always_inline)) typeof(name(0)) \ > > ____##name(struct pt_regs *ctx, ##args) > > -- > > 2.25.1 > >