linux-kernel - Re: [PATCH] UML: don't discard .text.exit section

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Date:	Wed, 17 Aug 2016 10:11:48 -0700
From:	Dmitry Vyukov <dvyukov@...gle.com>
To:	Andrey Ryabinin <aryabinin@...tuozzo.com>
Cc:	Jeff Dike <jdike@...toit.com>, Richard Weinberger <richard@....at>,
	user-mode-linux-devel <user-mode-linux-devel@...ts.sourceforge.net>,
	LKML <linux-kernel@...r.kernel.org>,
	Stefan Traby <stefan@...lo-penguin.com>,
	stable <stable@...r.kernel.org>
Subject: Re: [PATCH] UML: don't discard .text.exit section

On Wed, Aug 17, 2016 at 8:10 AM, Andrey Ryabinin
<aryabinin@...tuozzo.com> wrote:
> Commit e41f501d3912 ("vmlinux.lds: account for destructor sections")
> added '.text.exit' to EXIT_TEXT which is discarded at link time by default.
> This breaks compilation of UML:
>      `.text.exit' referenced in section `.fini_array' of
>      /usr/lib/gcc/x86_64-linux-gnu/6/../../../x86_64-linux-gnu/libc.a(sdlerror.o):
>      defined in discarded section `.text.exit' of
>      /usr/lib/gcc/x86_64-linux-gnu/6/../../../x86_64-linux-gnu/libc.a(sdlerror.o)
>
> Apparently UML doesn't want to discard exit text, so let's place all EXIT_TEXT
> sections in .exit.text.
>
> Fixes: e41f501d3912 ("vmlinux.lds: account for destructor sections")
> Reported-by: Stefan Traby <stefan@...lo-penguin.com>
> Signed-off-by: Andrey Ryabinin <aryabinin@...tuozzo.com>
> Cc: <stable@...r.kernel.org> # 4.0+
> ---
>  arch/um/include/asm/common.lds.S | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/um/include/asm/common.lds.S b/arch/um/include/asm/common.lds.S
> index 1dd5bd8..1330553 100644
> --- a/arch/um/include/asm/common.lds.S
> +++ b/arch/um/include/asm/common.lds.S
> @@ -81,7 +81,7 @@
>    .altinstr_replacement : { *(.altinstr_replacement) }
>    /* .exit.text is discard at runtime, not link time, to deal with references
>       from .altinstructions and .eh_frame */
> -  .exit.text : { *(.exit.text) }
> +  .exit.text : { EXIT_TEXT }
>    .exit.data : { *(.exit.data) }
>
>    .preinit_array : {
> --
> 2.7.3
>


Sorry for delays, I am travelling.
Do we need ".fini_array" section? It's also destructors that we don't
run. Or does UML use them? Does discarding ".fini_array" help?