diff mbox series

Mark __libc_freeres_fn as used [# 27002]

Message ID 20201202230943.4027351-1-hjl.tools@gmail.com
State Dropped
Headers show
Series Mark __libc_freeres_fn as used [# 27002] | expand

Commit Message

H.J. Lu Dec. 2, 2020, 11:09 p.m. UTC
GCC 11 with

commit 6fbec038f7a7ddf29f074943611b53210d17c40c
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Mon Feb 3 11:55:43 2020 -0800

    Use SHF_GNU_RETAIN to preserve symbol definitions

places used symbols in SECTION_RETAIN sections if assembler supports it.
Mark __libc_freeres_fn as used to avoid

In file included from <command-line>:
gconv_dl.c: In function 'free_mem':
gconv_dl.c:202:18: error: 'free_mem' causes a section type conflict with 'do_release_all'
  202 | libc_freeres_fn (free_mem)
      |                  ^~~~~~~~
./../include/libc-symbols.h:316:15: note: in definition of macro 'libc_freeres_fn'
  316 |   static void name (void)
      |               ^~~~
gconv_dl.c:191:1: note: 'do_release_all' was declared here
  191 | do_release_all (void *nodep)
      | ^~~~~~~~~~~~~~

where free_mem is marked as used.
---
 include/libc-symbols.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Florian Weimer Dec. 3, 2020, 9:39 a.m. UTC | #1
* H. J. Lu via Libc-alpha:

> GCC 11 with
>
> commit 6fbec038f7a7ddf29f074943611b53210d17c40c
> Author: H.J. Lu <hjl.tools@gmail.com>
> Date:   Mon Feb 3 11:55:43 2020 -0800
>
>     Use SHF_GNU_RETAIN to preserve symbol definitions
>
> places used symbols in SECTION_RETAIN sections if assembler supports it.
> Mark __libc_freeres_fn as used to avoid
>
> In file included from <command-line>:
> gconv_dl.c: In function 'free_mem':
> gconv_dl.c:202:18: error: 'free_mem' causes a section type conflict with 'do_release_all'
>   202 | libc_freeres_fn (free_mem)
>       |                  ^~~~~~~~
> ./../include/libc-symbols.h:316:15: note: in definition of macro 'libc_freeres_fn'
>   316 |   static void name (void)
>       |               ^~~~
> gconv_dl.c:191:1: note: 'do_release_all' was declared here
>   191 | do_release_all (void *nodep)
>       | ^~~~~~~~~~~~~~
>
> where free_mem is marked as used.

Why isn't this a GCC 11 bug?  Using SHF_GNU_RETAIN for existing code is
surprising.

Thanks,
Florian
H.J. Lu Dec. 3, 2020, 12:22 p.m. UTC | #2
On Thu, Dec 3, 2020 at 1:39 AM Florian Weimer <fweimer@redhat.com> wrote:
>
> * H. J. Lu via Libc-alpha:
>
> > GCC 11 with
> >
> > commit 6fbec038f7a7ddf29f074943611b53210d17c40c
> > Author: H.J. Lu <hjl.tools@gmail.com>
> > Date:   Mon Feb 3 11:55:43 2020 -0800
> >
> >     Use SHF_GNU_RETAIN to preserve symbol definitions
> >
> > places used symbols in SECTION_RETAIN sections if assembler supports it.
> > Mark __libc_freeres_fn as used to avoid
> >
> > In file included from <command-line>:
> > gconv_dl.c: In function 'free_mem':
> > gconv_dl.c:202:18: error: 'free_mem' causes a section type conflict with 'do_release_all'
> >   202 | libc_freeres_fn (free_mem)
> >       |                  ^~~~~~~~
> > ./../include/libc-symbols.h:316:15: note: in definition of macro 'libc_freeres_fn'
> >   316 |   static void name (void)
> >       |               ^~~~
> > gconv_dl.c:191:1: note: 'do_release_all' was declared here
> >   191 | do_release_all (void *nodep)
> >       | ^~~~~~~~~~~~~~
> >
> > where free_mem is marked as used.
>
> Why isn't this a GCC 11 bug?  Using SHF_GNU_RETAIN for existing code is
> surprising.

GCC 11 is changed to place the used symbol in SHF_GNU_RETAIN section to
support --gc-sections.  If you believe it is wrong, please file a GCC bug.
Florian Weimer Dec. 3, 2020, 1:36 p.m. UTC | #3
* H. J. Lu:

> GCC 11 is changed to place the used symbol in SHF_GNU_RETAIN section to
> support --gc-sections.  If you believe it is wrong, please file a GCC bug.

Okay, I filed: <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98121>

Thanks,
Florian
diff mbox series

Patch

diff --git a/include/libc-symbols.h b/include/libc-symbols.h
index b8103b98bb..b8fc1584d2 100644
--- a/include/libc-symbols.h
+++ b/include/libc-symbols.h
@@ -307,7 +307,7 @@  for linking")
 
 /* Resource freeing functions from libc.so go in this section.  */
 #define __libc_freeres_fn_section \
-  __attribute__ ((section ("__libc_freeres_fn")))
+  __attribute__ ((__used__, section ("__libc_freeres_fn")))
 
 /* Resource freeing functions for libc.so.  */
 #define libc_freeres_fn(name) \