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Re: [PATCH] Use dlsym to check if libdl is needed for plugin
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: Binutils <binutils at sourceware dot org>
- Cc: GCC Patches <gcc-patches at gcc dot gnu dot org>, GDB <gdb-patches at sourceware dot org>
- Date: Mon, 2 Apr 2018 04:55:11 -0700
- Subject: Re: [PATCH] Use dlsym to check if libdl is needed for plugin
- References: <20171019002520.GA4932@gmail.com>
On Wed, Oct 18, 2017 at 5:25 PM, H.J. Lu <hjl.tools@gmail.com> wrote:
> config/plugins.m4 has
>
> if test "$plugins" = "yes"; then
> AC_SEARCH_LIBS([dlopen], [dl])
> fi
>
> Plugin uses dlsym, but libasan.so only intercepts dlopen, not dlsym:
>
> [hjl@gnu-tools-1 binutils-text]$ nm -D /lib64/libasan.so.4| grep " dl"
> 0000000000038580 W dlclose
> U dl_iterate_phdr
> 000000000004dc50 W dlopen
> U dlsym
> U dlvsym
> [hjl@gnu-tools-1 binutils-text]$
>
> Testing dlopen for libdl leads to false negative when -fsanitize=address
> is used. It results in link failure:
>
> ../bfd/.libs/libbfd.a(plugin.o): undefined reference to symbol 'dlsym@@GLIBC_2.16'
>
> dlsym should be used to check if libdl is needed for plugin.
>
> OK for master?
>
> H.J.
> ---
> bfd/
>
> PR gas/22318
> * configure: Regenerated.
>
> binutils/
>
> PR gas/22318
> * configure: Regenerated.
>
> config/
>
> * plugins.m4 (AC_PLUGINS): Use dlsym to check if libdl is needed.
>
> gas/
>
> PR gas/22318
> * configure: Regenerated.
>
> gprof/
>
> PR gas/22318
> * configure: Regenerated.
>
> ld/
>
> PR gas/22318
> * configure: Regenerated.
> diff --git a/config/plugins.m4 b/config/plugins.m4
> index 513c690e1b..c6acebc1ca 100644
> --- a/config/plugins.m4
> +++ b/config/plugins.m4
> @@ -16,6 +16,6 @@ AC_DEFUN([AC_PLUGINS],
> [plugins=$maybe_plugins]
> )
> if test "$plugins" = "yes"; then
> - AC_SEARCH_LIBS([dlopen], [dl])
> + AC_SEARCH_LIBS([dlsym], [dl])
> fi
> ])
If there are no objections, I will check into binutils master branch this week.
--
H.J.