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 X-Spam-Level: X-Spam-Status: No, score=-17.9 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F1E86C4727C for ; Tue, 29 Sep 2020 20:26:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 818E32076D for ; Tue, 29 Sep 2020 20:26:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="F+IVhAIE" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728362AbgI2U0A (ORCPT ); Tue, 29 Sep 2020 16:26:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35682 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725372AbgI2UZ7 (ORCPT ); Tue, 29 Sep 2020 16:25:59 -0400 Received: from mail-pg1-x542.google.com (mail-pg1-x542.google.com [IPv6:2607:f8b0:4864:20::542]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BAC30C061755 for ; Tue, 29 Sep 2020 13:25:59 -0700 (PDT) Received: by mail-pg1-x542.google.com with SMTP id e18so4842232pgd.4 for ; Tue, 29 Sep 2020 13:25:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=HfMRjMpKzRlDMKyNSypttYHCWqFV6rG4s+gTfvHCn9o=; b=F+IVhAIEm5+w9caSbsklXW/Zz15I55StITvrN32TT5nzZfl7664u0Cv5kHk9dcdNsi ziYEEPl2KG3vHRQ4OMZqRMcBJv5TEPCBwZbn7Q0VakAtHBl+KSGHYBPpBh1SvaVrZRtP +Ad0cNxtyuuxJck1YidbjJzqrySGhTOrtfsTxIp6rKzXODRHcyqIHXnSTr1605p1MD9x V4mZX/TM3vPwgd5uU7zLb2Uprvm/MWYj82+qoSEmFCF92S9s5BGX+iH5zPfjDDH2eT+p loRZhMhGb1fe+YZTDWFpRmE6mS2fm3sjvWGaKv1ijpQfNl2++YwkvkNeZGZaq0wg+DxW npRw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=HfMRjMpKzRlDMKyNSypttYHCWqFV6rG4s+gTfvHCn9o=; b=rIKD+MYwYAIB5NrcDt2ymrDx7yo5qbK45LT41ynV2z2Q1N2jVsGEeatI2H9VuP+62E ozN62UQrb3hcbIxwHbvNg2Uqb6/aQ+mcSyOUTdnVxiNPex8ijo6ofN1IDI+v3NK3NH0i 9XkMwpykFmicZHx1cVEQ4k/B983UM78dVQXPRhrhZeauqdwMI7NuKBI3Df1qJOtJT11e od+5ZjsfyJa28OmsHGgJv9f89RLCWHejRaJQ9DAv6bZFwFr49X/3UOLPxWQl3uE9IiuA jyGxrvScBFYv7Qk+9obqYiw3hSEQGPF1OKqDMn9dCd0q0kuo6jltUbHEw0NPBF7Ism+Z dKhQ== X-Gm-Message-State: AOAM5315W622iEqQwfaT2JL36g5lRucBy+xoJysMr2DyvHRxAQy+UPMU xGqN60YUlSbBMVzqivNByTzVTmcxN2yUALeg4F3H9Q== X-Google-Smtp-Source: ABdhPJzkR3nxtaK5jFP39QpkEMUfVg/5RlAFvnIzVlO+WW8li8osllVX606KwonVvrKSnKVwgXPy5E4kjvfvcruecsA= X-Received: by 2002:a62:5586:0:b029:13e:d13d:a108 with SMTP id j128-20020a6255860000b029013ed13da108mr5642484pfb.36.1601411158903; Tue, 29 Sep 2020 13:25:58 -0700 (PDT) MIME-Version: 1.0 References: <20200929194318.548707-1-ndesaulniers@google.com> <20200929200801.GA2668747@rani.riverdale.lan> In-Reply-To: <20200929200801.GA2668747@rani.riverdale.lan> From: Nick Desaulniers Date: Tue, 29 Sep 2020 13:25:47 -0700 Message-ID: Subject: Re: [PATCH] compiler.h: avoid escaped section names To: Arvind Sankar Cc: Andrew Morton , Miguel Ojeda , Luc Van Oostenryck , Nathan Chancellor , linux-sparse@vger.kernel.org, LKML , clang-built-linux , Joe Perches Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-sparse@vger.kernel.org On Tue, Sep 29, 2020 at 1:08 PM Arvind Sankar wrote: > > On Tue, Sep 29, 2020 at 12:43:18PM -0700, Nick Desaulniers wrote: > > The stringification operator, `#`, in the preprocessor escapes strings. > > For example, `# "foo"` becomes `"\"foo\""`. GCC and Clang differ in how > > they treat section names that contain \". > > > > The portable solution is to not use a string literal with the > > preprocessor stringification operator. > > > > In this case, since __section unconditionally uses the stringification > > operator, we actually want the more verbose > > __attribute__((__section__())). > > > > Link: https://bugs.llvm.org/show_bug.cgi?id=42950 > > Fixes: commit e04462fb82f8 ("Compiler Attributes: remove uses of __attribute__ from compiler.h") > > Signed-off-by: Nick Desaulniers > > --- > > include/linux/compiler.h | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/include/linux/compiler.h b/include/linux/compiler.h > > index 92ef163a7479..ac45f6d40d39 100644 > > --- a/include/linux/compiler.h > > +++ b/include/linux/compiler.h > > @@ -155,7 +155,7 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val, > > extern typeof(sym) sym; \ > > static const unsigned long __kentry_##sym \ > > __used \ > > - __section("___kentry" "+" #sym ) \ > > + __attribute__((__section__("___kentry+" #sym))) \ > > = (unsigned long)&sym; > > #endif > > > > -- > > 2.28.0.709.gb0816b6eb0-goog > > > > There was this previous mini-thread: > https://lore.kernel.org/lkml/20200629205448.GA1474367@rani.riverdale.lan/ > and this older one: > https://lore.kernel.org/lkml/20190904181740.GA19688@gmail.com/ > > Just for my own curiosity: how does KENTRY actually get used? grep > doesn't show any hits, and the thread from 2019 was actually going to > drop it if I read it right, and also just remove stringification from > the __section macro. Oh, sorry I didn't respond on that thread; I could have sworn I ran a grep for KENTRY back then. $ git log -S KENTRY Doesn't seem to get any hits, so I'm not sure what I should use for a proper Fixes tag in the event we just remove it. Let me grab lunch, then I'll send a v2 that just removes the KENTRY block. Thanks for the reminder! And I don't remember what ever happened to Joe's script for treewide conversion of __section. -- Thanks, ~Nick Desaulniers