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PING^2: [PATCH] Use dlsym to check if libdl is needed for plugin
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: "H.J. Lu" <hjl dot tools at gmail dot com>, DJ Delorie <dj at redhat dot com>, Alexandre Oliva <aoliva at redhat dot com>
- Cc: GCC Patches <gcc-patches at gcc dot gnu dot org>
- Date: Wed, 14 Mar 2018 04:41:59 -0700
- Subject: PING^2: [PATCH] Use dlsym to check if libdl is needed for plugin
- Authentication-results: sourceware.org; auth=none
On Wed, Feb 21, 2018 at 3:02 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
> 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.
PING.
--
H.J.
From 8157f3e03107e77b8306d4ab1388a63548a13470 Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Wed, 18 Oct 2017 17:18:37 -0700
Subject: [PATCH] Use dlsym to check if libdl is needed for plugin
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.
* plugins.m4 (AC_PLUGINS): Use dlsym to check if libdl is needed.
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
])