linux-kernel - Re: [tip: objtool/urgent] objtool: Fix seg fault with Clang non-section symbols

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Message-ID: <20210215155806.bjcouvmkapj4pa4y@treble>
Date:   Mon, 15 Feb 2021 09:58:06 -0600
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Xi Ruoyao <xry111@...gyan1223.wang>,
        "# 3.4.x" <stable@...r.kernel.org>,
        Arnd Bergmann <arnd@...nel.org>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Miroslav Benes <mbenes@...e.cz>,
        "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-tip-commits@...r.kernel.org
Subject: Re: [tip: objtool/urgent] objtool: Fix seg fault with Clang
 non-section symbols

On Mon, Feb 15, 2021 at 09:53:07AM -0500, Steven Rostedt wrote:
> On Sun, 14 Feb 2021 09:51:47 -0600
> Josh Poimboeuf <jpoimboe@...hat.com> wrote:
> 
> > Steve, looks like recordmcount avoids referencing weak symbols directly
> > by their function symbol.  Maybe it can just skip weak symbols which
> > don't have a section symbol, since this seems like a rare scenario.
> 
> When does the .text.unlikely section disappear? During the creation of the
> object, or later in the linker stage?

The section is there, but the symbol associated with the section
(".text.unlikely" symbol) isn't generated by the assembler.

-- 
Josh