Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Thu, 27 Apr 2023 11:14:21 +0200
From:   Borislav Petkov <bp@alien8.de>
To:     "Paul E. McKenney" <paulmck@kernel.org>
Cc:     jpoimboe@kernel.org, peterz@infradead.org,
        linux-kernel@vger.kernel.org
Subject: Re: An objtool warning from mainline
Message-ID: <20230427091421.GAZEo87ezQPLwLKiPF@fat_crate.local>
References: <02bd36cf-b2b8-4634-a70b-1476420188c8@paulmck-laptop>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
In-Reply-To: <02bd36cf-b2b8-4634-a70b-1476420188c8@paulmck-laptop>
Precedence: bulk

On Wed, Apr 26, 2023 at 04:50:49PM -0700, Paul E. McKenney wrote:
> vmlinux.o: warning: objtool: exc_nmi+0x2b3: call to __const_udelay() leaves .noinstr.text section

What does

./scripts/faddr2line vmlinux.o exc_nmi+0x2b3

say?

I guess it should point to io_check_error()'s udelay().

If so, it is noinline:

81423c37415f ("x86/timer: Don't inline __const_udelay()")

> I see this with gcc version 11.3.0 (Ubuntu 11.3.0-1ubuntu1~22.04) and also with
> gcc version 8.5.0 20210514 (Red Hat 8.5.0-18) (GCC).

I can't trigger it here with

gcc-11 (Debian 11.2.0-19) 11.2.0

Which is weird because the asm looks like it should warn.

Does it go away if you remove the noinline before __const_udelay()?

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette