Add hidden visibility to internal function prototypes

Add hidden visibility to internal function prototypes to allow direct
access to internal functions within libc.a without using GOT when the
compiler defaults to -fPIE.

Size comparison of elf/ldconfig when the compiler defaults to -fPIE:

On x86-64:
        text	   data	    bss	    dec	    hex
Before: 619646	  20132	   5488	 645266	  9d892
After : 619502	  20132	   5488	 645122	  9d802
On i686:
        text	   data	    bss	    dec	    hex
Before: 550333	  10748	   3060	 564141	  89bad
After : 546453	  10732	   3060	 560245	  88c75

	* include/libc-symbols.h (__hidden_proto_hiddenattr): New for
	building libc.a.
	(hidden_proto): Likewise.
	(hidden_tls_proto): Likewise.
	(__hidden_proto): Likewise.

(Reapplied after the revert in df1deda60050cc8a68156cf6c81ad42363647a29.)

diff --git a/ChangeLog b/ChangeLog
index 753257810b7a81dbca0eb75f35f938dc010c479d..53fdcb496a30979659a4b5e01b026a67fe6ed0a0 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2017-08-22  H.J. Lu  <hongjiu.lu@intel.com>
+
+       * include/libc-symbols.h (__hidden_proto_hiddenattr): New for
+       building libc.a.
+       (hidden_proto): Likewise.
+       (hidden_tls_proto): Likewise.
+       (__hidden_proto): Likewise.
+
 2017-08-22  Florian Weimer  <fweimer@redhat.com>
 
        math: Statically link tests of internal functionality.

diff --git a/include/libc-symbols.h b/include/libc-symbols.h
index d6a1c260f6cb80aacd16c9b1b991559421419cf3..fe3571af52925f1c9cb8e2211d5914cf2ca08986 100644 (file)
--- a/include/libc-symbols.h
+++ b/include/libc-symbols.h
@@ -513,8 +513,20 @@ for linking")
 # endif
 #else
 # ifndef __ASSEMBLER__
-#  define hidden_proto(name, attrs...)
-#  define hidden_tls_proto(name, attrs...)
+#  if !defined SHARED && IS_IN (libc) && !defined LIBC_NONSHARED \
+      && !defined NO_HIDDEN
+#   define __hidden_proto_hiddenattr(attrs...) \
+  __attribute__ ((visibility ("hidden"), ##attrs))
+#   define hidden_proto(name, attrs...) \
+  __hidden_proto (name, , name, ##attrs)
+#   define hidden_tls_proto(name, attrs...) \
+  __hidden_proto (name, __thread, name, ##attrs)
+#  define __hidden_proto(name, thread, internal, attrs...)          \
+  extern thread __typeof (name) name __hidden_proto_hiddenattr (attrs);
+# else
+#   define hidden_proto(name, attrs...)
+#   define hidden_tls_proto(name, attrs...)
+# endif
 # else
 #  define HIDDEN_JUMPTARGET(name) JUMPTARGET(name)
 # endif /* Not  __ASSEMBLER__ */