linux-kernel - Re: [PATCH] x86/sev: Mark snp

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Message-ID: <20220824172929.GA25951@gate.crashing.org>
Date:   Wed, 24 Aug 2022 12:29:29 -0500
From:   Segher Boessenkool <segher@...nel.crashing.org>
To:     Borislav Petkov <bp@...en8.de>
Cc:     X86 ML <x86@...nel.org>, Michael Matz <matz@...e.de>,
        linux-toolchains@...r.kernel.org,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86/sev: Mark snp_abort() noreturn

Hi!

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?  It sounds like you need this
(and then fix all resulting warnings) to not upset objtool?

It is nice to have this anyway (if there aren't a zillion false
positives), but it seems objtool is very fragile.


Segher