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Date:   Wed, 21 Oct 2020 13:04:35 -0700
From:   Kees Cook <keescook@chromium.org>
To:     Ingo Molnar <mingo@kernel.org>, x86@kernel.org
Cc:     Stephen Rothwell <sfr@canb.auug.org.au>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Arnd Bergmann <arnd@arndb.de>,
        clang-built-linux@googlegroups.com, linux-arch@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] vmlinux.lds.h: Keep .ctors.* with .ctors
Message-ID: <202010211303.4F8386F2@keescook>
References: <20201005025720.2599682-1-keescook@chromium.org>
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[thread ping: x86 maintainers, can someone please take this?]

On Sun, Oct 04, 2020 at 07:57:20PM -0700, Kees Cook wrote:
> Under some circumstances, the compiler generates .ctors.* sections. This
> is seen doing a cross compile of x86_64 from a powerpc64el host:
> 
> x86_64-linux-gnu-ld: warning: orphan section `.ctors.65435' from `kernel/trace/trace_clock.o' being
> placed in section `.ctors.65435'
> x86_64-linux-gnu-ld: warning: orphan section `.ctors.65435' from `kernel/trace/ftrace.o' being
> placed in section `.ctors.65435'
> x86_64-linux-gnu-ld: warning: orphan section `.ctors.65435' from `kernel/trace/ring_buffer.o' being
> placed in section `.ctors.65435'
> 
> Include these orphans along with the regular .ctors section.
> 
> Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
> Tested-by: Stephen Rothwell <sfr@canb.auug.org.au>
> Fixes: 83109d5d5fba ("x86/build: Warn on orphan section placement")
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
> v2: brown paper bag version: fix whitespace for proper backslash alignment
> ---
>  include/asm-generic/vmlinux.lds.h | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
> index 5430febd34be..b83c00c63997 100644
> --- a/include/asm-generic/vmlinux.lds.h
> +++ b/include/asm-generic/vmlinux.lds.h
> @@ -684,6 +684,7 @@
>  #ifdef CONFIG_CONSTRUCTORS
>  #define KERNEL_CTORS()	. = ALIGN(8);			   \
>  			__ctors_start = .;		   \
> +			KEEP(*(SORT(.ctors.*)))		   \
>  			KEEP(*(.ctors))			   \
>  			KEEP(*(SORT(.init_array.*)))	   \
>  			KEEP(*(.init_array))		   \
> -- 
> 2.25.1
> 

-- 
Kees Cook