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Date:   Mon, 24 Oct 2022 10:32:58 -0700
From:   Kees Cook <keescook@chromium.org>
To:     Nathan Chancellor <nathan@kernel.org>
Cc:     Xin Li <xin3.li@intel.com>, linux-kernel@vger.kernel.org,
        llvm@lists.linux.dev, linux-kbuild@vger.kernel.org, x86@kernel.org,
        andrew.cooper3@citrix.com, hpa@zytor.com, peterz@infradead.org
Subject: Re: [PATCH 1/1] kbuild: upgrade the orphan section warning to an
 error if CONFIG_WERROR is set
Message-ID: <202210241031.4BB6E70FB@keescook>
References: <20221022030519.9505-1-xin3.li@intel.com>
 <20221022030519.9505-2-xin3.li@intel.com>
 <Y1bLk47I4pyEmJVi@dev-arch.thelio-3990X>
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On Mon, Oct 24, 2022 at 10:29:55AM -0700, Nathan Chancellor wrote:
> On Fri, Oct 21, 2022 at 08:05:19PM -0700, Xin Li wrote:
> > Andrew Cooper suggested upgrading the orphan section warning to a hard link
> > error. However Nathan Chancellor said outright turning the warning into an
> > error with no escape hatch might be too aggressive, as we have had these
> > warnings triggered by new compiler generated sections, and suggested turning
> > orphan sections into an error only if CONFIG_WERROR is set. Kees Cook echoed
> > and emphasized that the mandate from Linus is that we should avoid breaking
> > builds. It wrecks bisection, it causes problems across compiler versions, etc.
> > 
> > Thus upgrade the orphan section warning to a hard link error only if
> > CONFIG_WERROR is set.
> > 
> > Suggested-by: Andrew Cooper <andrew.cooper3@citrix.com>
> > Suggested-by: Nathan Chancellor <nathan@kernel.org>
> > Signed-off-by: Xin Li <xin3.li@intel.com>
> 
> Thanks for the patch!
> 
> Reviewed-by: Nathan Chancellor <nathan@kernel.org>
> Tested-by: Nathan Chancellor <nathan@kernel.org>
> 
> We could deduplicate the '$(if $(CONFIG_WERROR),error,warn)' logic if we
> hoisted it into Kconfig by having something like
> 
>     config LD_ORPHAN_WARN_LEVEL
>         string
>         depends on LD_ORPHAN_WARN
>         default "error" if WERROR
>         default "warn"
> 
> in init/Kconfig then using it everywhere like
> 
>     --orphan-handling=$(CONFIG_LD_ORPHAN_WARN_LEVEL)
> 
> but I will let others decide if they would prefer that over the
> direction we went here.

I think this makes it look cleaner, yeah.

-- 
Kees Cook