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Date:   Wed, 24 Aug 2022 14:43:49 -0500
From:   Segher Boessenkool <segher@kernel.crashing.org>
To:     Nick Desaulniers <ndesaulniers@google.com>
Cc:     Borislav Petkov <bp@alien8.de>, X86 ML <x86@kernel.org>,
        Michael Matz <matz@suse.de>, linux-toolchains@vger.kernel.org,
        LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] x86/sev: Mark snp_abort() noreturn
Message-ID: <20220824194349.GB25951@gate.crashing.org>
References: <20220824152420.20547-1-bp@alien8.de> <20220824172929.GA25951@gate.crashing.org> <CAKwvOdm+yFhZ2pYLJ5vpj1YyNJmG=UVF4cTz_m+0UfDGNGsRbQ@mail.gmail.com>
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On Wed, Aug 24, 2022 at 11:44:35AM -0700, Nick Desaulniers wrote:
> On Wed, Aug 24, 2022 at 10:33 AM Segher Boessenkool
> <segher@kernel.crashing.org> wrote:
> > On Wed, Aug 24, 2022 at 05:24:20PM +0200, Borislav Petkov wrote:
> > > Mark both the function prototype and definition as noreturn in order to
> > > prevent the compiler from doing transformations which confuse objtool
> > > like so:
> > >
> > >   vmlinux.o: warning: objtool: sme_enable+0x71: unreachable instruction
> >
> > Would -Wmissing-noreturn have caught this?
> 
> Oh, that's shiny. Is that relatively new?

Relatively, yes.


commit 0ca3fb0a168e9db2bd5405855d3932f62b08b7c9
Author: Kaveh R. Ghazi <ghazi@caip.rutgers.edu>
Date:   Tue Oct 20 07:32:08 1998 +0000

    New warning, `missing-noreturn':


The alias -Wsuggest-attribute=noreturn is newer:


commit 94ee697923f5a93881edbc5e1b3f810b290f0fc7
Author: Manuel L?pez-Ib??ez <manu@gcc.gnu.org>
Date:   Sun Apr 29 09:15:30 2012 +0000

	* common.opt (Wmissing-noreturn): Alias of -Wsuggest-attribute=noret


Segher