Create hidden aliases for non-libc syscalls automatically.

The syscall wrappers mechanism automatically creates hidden aliases
for syscalls with libc_hidden_def / libc_hidden_weak.  The use of
libc_hidden_* has the side-effect that for syscall wrappers in
non-libc libraries those aliases are not created.  In turn, this means
that three mq_* syscalls in sysdeps/unix/sysv/linux/syscalls.list list
the __GI_* names explicitly.

The use of libc_hidden_* dates back to the original introduction of
that support in

2002-08-03  Roland McGrath  <roland@redhat.com>

        * sysdeps/unix/make-syscalls.sh: Generate libc_hidden_def or
        libc_hidden_weak for every system call symbol defined.

(predating the non-libc syscalls in question) and I see no reason for
excluding non-libc syscalls.  This patch changes the code to use
hidden_def / hidden_weak (via a wrapper syscall_hidden_def in the case
where the argument is itself a macro, so that the argument gets
expanded before concatenation with __GI_), so avoiding the need to
specify the hidden aliases explicitly in this case.

Tested for x86_64 and x86 (testsuite, and that disassembly of
installed stripped shared libraries is unchanged by the patch; the
mq_* symbols change from weak to strong, which is of no significance
and two of them will shortly change back to weak as part of a fix for
bug 18545).

	* sysdeps/unix/make-syscalls.sh (emit_weak_aliases): Use
	hidden_def and hidden_weak instead of libc_hidden_def and
	libc_hidden_weak.
	(top level): Refer to hidden_def in comment.
	* sysdeps/unix/syscall-template.S (syscall_hidden_def): New
	macro.  Use it instead of libc_hidden_def.
	* sysdeps/unix/sysv/linux/syscalls.list (mq_timedsend): Do not
	specify __GI_* name explicitly.
	(mq_timedreceive): Likewise.
	(mq_setattr): Likewise.

ChangeLog

@@ -1,5 +1,16 @@
 2015-06-17  Joseph Myers  <joseph@codesourcery.com>
 
+	* sysdeps/unix/make-syscalls.sh (emit_weak_aliases): Use
+	hidden_def and hidden_weak instead of libc_hidden_def and
+	libc_hidden_weak.
+	(top level): Refer to hidden_def in comment.
+	* sysdeps/unix/syscall-template.S (syscall_hidden_def): New
+	macro.  Use it instead of libc_hidden_def.
+	* sysdeps/unix/sysv/linux/syscalls.list (mq_timedsend): Do not
+	specify __GI_* name explicitly.
+	(mq_timedreceive): Likewise.
+	(mq_setattr): Likewise.
+
 	[BZ #18544]
 	* nptl/pthread_barrier_init.c (pthread_barrier_init): Rename to
 	__pthread_barrier_init and define as weak alias of

sysdeps/unix/make-syscalls.sh

@@ -128,11 +128,11 @@ emit_weak_aliases()
       !*)
 	name=`echo $name | sed 's/.//'`
 	echo "	 echo 'strong_alias ($strong, $name)'; \\"
-	echo "	 echo 'libc_hidden_def ($name)'; \\"
+	echo "	 echo 'hidden_def ($name)'; \\"
 	;;
       *)
 	echo "	 echo 'weak_alias ($strong, $name)'; \\"
-	echo "	 echo 'libc_hidden_weak ($name)'; \\"
+	echo "	 echo 'hidden_weak ($name)'; \\"
 	;;
     esac
   done
@@ -287,7 +287,7 @@ while read file srcfile caller syscall args strong weak; do
 	 echo '}'; \\
 	 echo 'asm (".type ${strong}, %gnu_indirect_function");'; \\
 EOF
-    # This is doing "libc_hidden_def (${strong})", but the compiler
+    # This is doing "hidden_def (${strong})", but the compiler
     # doesn't know that we've defined ${strong} in the same file, so
     # we can't do it the normal way.
     cat <<EOF

sysdeps/unix/syscall-template.S

@@ -47,6 +47,9 @@
 # include <sysdep.h>
 #endif
 
+/* This indirection is needed so that SYMBOL gets macro-expanded.  */
+#define syscall_hidden_def(SYMBOL)		hidden_def (SYMBOL)
+
 #define T_PSEUDO(SYMBOL, NAME, N)		PSEUDO (SYMBOL, NAME, N)
 #define T_PSEUDO_NOERRNO(SYMBOL, NAME, N)	PSEUDO_NOERRNO (SYMBOL, NAME, N)
 #define T_PSEUDO_ERRVAL(SYMBOL, NAME, N)	PSEUDO_ERRVAL (SYMBOL, NAME, N)
@@ -84,4 +87,4 @@ T_PSEUDO_END (SYSCALL_SYMBOL)
 
 #endif
 
-libc_hidden_def (SYSCALL_SYMBOL)
+syscall_hidden_def (SYSCALL_SYMBOL)

sysdeps/unix/sysv/linux/syscalls.list

@@ -106,9 +106,9 @@ removexattr	-	removexattr	i:ss	removexattr
 lremovexattr	-	lremovexattr	i:ss	lremovexattr
 fremovexattr	-	fremovexattr	i:is	fremovexattr
 
-mq_timedsend	-	mq_timedsend	Ci:ipiip	__GI_mq_timedsend	mq_timedsend
-mq_timedreceive	-	mq_timedreceive	Ci:ipipp	__GI_mq_timedreceive	mq_timedreceive
-mq_setattr	-	mq_getsetattr	i:ipp	__GI_mq_setattr	mq_setattr
+mq_timedsend	-	mq_timedsend	Ci:ipiip	mq_timedsend
+mq_timedreceive	-	mq_timedreceive	Ci:ipipp	mq_timedreceive
+mq_setattr	-	mq_getsetattr	i:ipp	mq_setattr
 
 timerfd_create	EXTRA	timerfd_create	i:ii	timerfd_create
 timerfd_settime	EXTRA	timerfd_settime	i:iipp	timerfd_settime