: hurd: Do not hide rtld symbols which need to be preempted [Was: hurd: Hidden symbols in rtld]
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Message ID 20160320170528.GO3635@var.home
State New
Headers show

Commit Message

Samuel Thibault March 20, 2016, 5:05 p.m. UTC
Samuel Thibault, on Sun 20 Mar 2016 17:42:14 +0100, wrote:
> AIUI, this is because there are weak definitions in
> sysdeps/mach/hurd/dl-sysdep.c which need to be preempted by the libc
> one, right?  Is __access perhaps missing in the list?  There is a weak
> definition for __access in dl-sysdep.c.
> 
> Also, 6d56699d7e808419ccf244150ecba122156932ba ('Mark internal fcntl
> functions hidden') made __open hidden, but dl-sysdep.c has a weak
> definition, which AIUI needs to be preempted too, so that this commit
> should be split to a dl-fcntl.h that sysdepas/mach/hurd/ can provide,
> right?
> 
> (Just asking the question, I'll handle commiting etc.)

Just to explicit things, attached is the fix I'm considering.

Samuel
commit 627af5c461b01bf7fe13c707470afdcb5c8ea59c
Author: Samuel Thibault <samuel.thibault@ens-lyon.org>
Date:   Sun Mar 20 17:56:47 2016 +0100

    hurd: Do not hide rtld symbols which need to be preempted
    
    	* sysdeps/generic/dl-fcntl.h: New file, hides __open and __fcntl.
    	* sysdeps/mach/hurd/dl-fcntl.h: New file, hides __fcntl only.
    	* include/fcntl.h [IS_IN (rtld)]: Include <dl-fcntl.h> instead of
    	hiding __open and __fcntl.
    	* sysdeps/mach/hurd/dl-unistd.h: Do not hide __access.

Comments

H.J. Lu March 20, 2016, 5:14 p.m. UTC | #1
On Sun, Mar 20, 2016 at 10:05 AM, Samuel Thibault
<samuel.thibault@ens-lyon.org> wrote:
> Samuel Thibault, on Sun 20 Mar 2016 17:42:14 +0100, wrote:
>> AIUI, this is because there are weak definitions in
>> sysdeps/mach/hurd/dl-sysdep.c which need to be preempted by the libc
>> one, right?  Is __access perhaps missing in the list?  There is a weak
>> definition for __access in dl-sysdep.c.
>>
>> Also, 6d56699d7e808419ccf244150ecba122156932ba ('Mark internal fcntl
>> functions hidden') made __open hidden, but dl-sysdep.c has a weak
>> definition, which AIUI needs to be preempted too, so that this commit
>> should be split to a dl-fcntl.h that sysdepas/mach/hurd/ can provide,
>> right?
>>
>> (Just asking the question, I'll handle commiting etc.)

It is not about weak nor not.  By default, there is no difference
between weak defined symbol and non-weak defined symbols
at run-time.

The question should be asked is if __access in dl-sysdep.c can
be used in ld.so after bootstrap on Hurd.

> Just to explicit things, attached is the fix I'm considering.
>
> Samuel
Samuel Thibault March 20, 2016, 5:31 p.m. UTC | #2
H.J. Lu, on Sun 20 Mar 2016 10:14:40 -0700, wrote:
> >> Is __access perhaps missing in the list?  There is a weak
> >> definition for __access in dl-sysdep.c.
[...]
> It is not about weak nor not.  By default, there is no difference
> between weak defined symbol and non-weak defined symbols
> at run-time.

Ah, right.

> The question should be asked is if __access in dl-sysdep.c can
> be used in ld.so after bootstrap on Hurd.

Ok.  It seems it's only used in dl_main and in process_envvars only
called by dl_main, so it should be fine, right?

About __open, it's definitely used for dlopen() :)

Thanks,
Samuel
H.J. Lu March 20, 2016, 5:36 p.m. UTC | #3
On Sun, Mar 20, 2016 at 10:31 AM, Samuel Thibault
<samuel.thibault@ens-lyon.org> wrote:
> H.J. Lu, on Sun 20 Mar 2016 10:14:40 -0700, wrote:
>> >> Is __access perhaps missing in the list?  There is a weak
>> >> definition for __access in dl-sysdep.c.
> [...]
>> It is not about weak nor not.  By default, there is no difference
>> between weak defined symbol and non-weak defined symbols
>> at run-time.
>
> Ah, right.
>
>> The question should be asked is if __access in dl-sysdep.c can
>> be used in ld.so after bootstrap on Hurd.
>
> Ok.  It seems it's only used in dl_main and in process_envvars only
> called by dl_main, so it should be fine, right?
>
> About __open, it's definitely used for dlopen() :)

I don't know since they are Hurd specific.
Samuel Thibault March 20, 2016, 5:54 p.m. UTC | #4
H.J. Lu, on Sun 20 Mar 2016 10:42:11 -0700, wrote:
> On Sun, Mar 20, 2016 at 10:40 AM, Samuel Thibault
> <samuel.thibault@ens-lyon.org> wrote:
> > H.J. Lu, on Sun 20 Mar 2016 10:36:45 -0700, wrote:
> >> On Sun, Mar 20, 2016 at 10:31 AM, Samuel Thibault
> >> <samuel.thibault@ens-lyon.org> wrote:
> >> > H.J. Lu, on Sun 20 Mar 2016 10:14:40 -0700, wrote:
> >> >> The question should be asked is if __access in dl-sysdep.c can
> >> >> be used in ld.so after bootstrap on Hurd.
> >> >
> >> > Ok.  It seems it's only used in dl_main and in process_envvars only
> >> > called by dl_main, so it should be fine, right?
> >> >
> >> > About __open, it's definitely used for dlopen() :)
> >>
> >> I don't know since they are Hurd specific.
> >
> > ? dl_main, process_envvars, __open and dlopen are not Hurd specific.
> 
> Whether a function defined in ld.so can be used after bootstrap is
> Hurd specific.

Sure, but for __open() for instance, its reference from dl-load.c is not
Hurd-specific, so it is clearly used for dlopen() after bootstrap.

Samuel
Florian Weimer July 7, 2016, 5:35 a.m. UTC | #5
On 03/20/2016 06:05 PM, Samuel Thibault wrote:
>     hurd: Do not hide rtld symbols which need to be preempted
>
>     	* sysdeps/generic/dl-fcntl.h: New file, hides __open and __fcntl.
>     	* sysdeps/mach/hurd/dl-fcntl.h: New file, hides __fcntl only.
>     	* include/fcntl.h [IS_IN (rtld)]: Include <dl-fcntl.h> instead of
>     	hiding __open and __fcntl.
>     	* sysdeps/mach/hurd/dl-unistd.h: Do not hide __access.

How did you test this, considering that master is quite far away from 
building on master?

Thanks,
Florian

Patch
diff mbox

diff --git a/ChangeLog b/ChangeLog
index ce46c6b..aa151cf 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@ 
+2016-03-20  Samuel Thibault  <samuel.thibault@ens-lyon.org>:
+
+	* sysdeps/generic/dl-fcntl.h: New file, hides __open and __fcntl.
+	* sysdeps/mach/hurd/dl-fcntl.h: New file, hides __fcntl only.
+	* include/fcntl.h [IS_IN (rtld)]: Include <dl-fcntl.h> instead of
+	hiding __open and __fcntl.
+	* sysdeps/mach/hurd/dl-unistd.h: Do not hide __access.
+
 2016-03-20  Samuel Thibault  <samuel.thibault@ens-lyon.org>
 
 	* sysdeps/mach/hurd/Makefile ($(common-objpfx)errnos.d): Strip
diff --git a/include/fcntl.h b/include/fcntl.h
index 4168ee4..3b2c887 100644
--- a/include/fcntl.h
+++ b/include/fcntl.h
@@ -31,8 +31,7 @@  extern int __openat64_2 (int __fd, const char *__path, int __oflag);
 
 
 #if IS_IN (rtld)
-extern __typeof (__open) __open attribute_hidden;
-extern __typeof (__fcntl) __fcntl attribute_hidden;
+#  include <dl-fcntl.h>
 #endif
 
 /* Flag determining whether the *at system calls are available.  */
diff --git a/sysdeps/generic/dl-fcntl.h b/sysdeps/generic/dl-fcntl.h
new file mode 100644
index 0000000..ee3c49c
--- /dev/null
+++ b/sysdeps/generic/dl-fcntl.h
@@ -0,0 +1,21 @@ 
+/* Functions with hidden attribute internal to ld.so, which are declared
+   in include/fcntl.h.  Generic version.
+   Copyright (C) 2016 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+extern __typeof (__open) __open attribute_hidden;
+extern __typeof (__fcntl) __fcntl attribute_hidden;
diff --git a/sysdeps/mach/hurd/dl-fcntl.h b/sysdeps/mach/hurd/dl-fcntl.h
new file mode 100644
index 0000000..0fef2f1
--- /dev/null
+++ b/sysdeps/mach/hurd/dl-fcntl.h
@@ -0,0 +1,22 @@ 
+/* Functions with hidden attribute internal to ld.so, which are declared
+   in include/fcntl.h.  Hurd version.
+   Copyright (C) 2016 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+/* __open can't be hidden in ld.so on Hurd since they will be preempted by the
+   ones in libc.so after bootstrap.  */
+extern __typeof (__fcntl) __fcntl attribute_hidden;
diff --git a/sysdeps/mach/hurd/dl-unistd.h b/sysdeps/mach/hurd/dl-unistd.h
index b3cfb61..88bdd80 100644
--- a/sysdeps/mach/hurd/dl-unistd.h
+++ b/sysdeps/mach/hurd/dl-unistd.h
@@ -17,10 +17,9 @@ 
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
-/* __close, __getcwd, __getpid, __libc_read and __libc_write can't be
+/* __access, __close, __getcwd, __getpid, __libc_read and __libc_write can't be
    hidden in ld.so on Hurd since they will be preempted by the ones in
    libc.so after bootstrap.  */
-extern __typeof (__access) __access attribute_hidden;
 extern __typeof (__brk) __brk attribute_hidden;
 extern __typeof (__lseek) __lseek attribute_hidden;
 extern __typeof (__profil) __profil attribute_hidden;