[PATCH] Introduce NO_RTLD_HIDDEN, make hurd use it instead of NO_HIDDEN

[Samuel Thibault <samuel dot thibault at ens-lyon dot org>]

On the Hurd, the rtld needs to see its own dumb versions of a few
functions (defined in sysdeps/mach/hurd/dl-sysdep.c) overridden
by libc's versions once loaded. rtld should thus not have hidden
attribute for these.  To achieve this, the Hurd port used to just define
NO_HIDDEN, which disables it completely. For now, this changes that to
disabling it for all rtld functions, for simplicity. In reality fewer
functions need to be not-hidden, those needed early during the load.

See Roland's comment on https://sourceware.org/bugzilla/show_bug.cgi?id=15605#c5

The ld.so numbers thus remain at

  8 .rel.plt      000000c8  00000c24  00000c24  00000c24  2**2
                  CONTENTS, ALLOC, LOAD, READONLY, DATA
  9 .plt          000001a0  00000cf0  00000cf0  00000cf0  2**4
                  CONTENTS, ALLOC, LOAD, READONLY, CODE
 10 .plt.got      00000010  00000e90  00000e90  00000e90  2**3
                  CONTENTS, ALLOC, LOAD, READONLY, CODE
 18 .got.plt      00000070  0002d000  0002d000  0002c000  2**2
                  CONTENTS, ALLOC, LOAD, DATA

which is about 3 times as much as on Linux. About half of them are due
to these functions which need to be overriden by libc.so anyway. So
perhaps it's fine to go this way and not try to specifically mark the
functions which need to be not-hidden.

The libc.so numbers get divided by 3 (the remainings are mostly RPC stub calls).

We could then remove the NO_HIDDEN macro, and only keep the
NO_RTLD_HIDDEN macro.

* include/libc-symbols.h [NO_RTLD_HIDDEN] (rtld_hidden_proto,
rtld_hidden_tls_proto, rtld_hidden_def, rtld_hidden_weak, rtld_hidden_ver,
rtld_hidden_data_def, rtld_hidden_data_weak, rtld_hidden_data_ver): Define to
empty.
* include/stdlib.h [NO_RTLD_HIDDEN] (unsetenv, __strtoul_internal): Do not set
hidden attribute.
* include/assert.h [IS_IN(rtld) && NO_RTLD_HIDDEN] (__assert_fail,
__assert_perror_fail): Likewise.
* include/dirent.h [IS_IN(rtld) && NO_RTLD_HIDDEN] (__closedir, __fdopendir,
__readdir, __readdir64, __rewinddir): Likewise.
* include/libc-internal.h [IS_IN(rtld) && NO_RTLD_HIDDEN]
(__profile_frequency): Likewise.
* include/signal.h [IS_IN(rtld) && NO_RTLD_HIDDEN] (__sigaction,
__libc_sigaction): Likewise.
* include/string.h [IS_IN(rtld) && NO_RTLD_HIDDEN] (__stpcpy, __strdup,
__strerror_t, __strsep_g, memchr, memcmp, memcpy, memmove, memset, rawmemchr,
stpcpy, strchr, strcmp, strlen, strnlen, strsep): Likewise.
* include/sys/stat.h [IS_IN(rtld) && NO_RTLD_HIDDEN] (__fxstat, __fxstat64,
__lxstat, __lxstat64, __xstat, __xstat64, __fxstatat64): Likewise.
* include/sys/utsname.h [IS_IN(rtld) && NO_RTLD_HIDDEN] (__uname): Likewise.
* include/sysdeps/generic/_itoa.h [IS_IN(rtld) && NO_RTLD_HIDDEN]
(_itoa_upper_digits, _itoa_lower_digits): Likewise.
* sysdeps/i386/dl-tlsdesc.S [NO_RTLD_HIDDEN] (_dl_tlsdesc_dynamic): Call
JUMPTARGET (___tls_get_addr) instead of HIDDEN_JUMPTARGET (___tls_get_addr).
* sysdeps/mach/hurd/configure.ac (NO_HIDDEN): Do not set.
(NO_RTLD_HIDDEN): Set.
* sysdeps/mach/hurd/configure: Refresh.
* config.h.in (NO_RTLD_HIDDEN): Add undefined macro.

Index: glibc-2.26/include/libc-symbols.h
===================================================================
--- glibc-2.26.orig/include/libc-symbols.h
+++ glibc-2.26/include/libc-symbols.h
@@ -544,7 +544,7 @@ for linking")
 # define libc_hidden_data_ver(local, name)
 #endif
 
-#if IS_IN (rtld)
+#if IS_IN (rtld) && !defined NO_RTLD_HIDDEN
 # define rtld_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
 # define rtld_hidden_tls_proto(name, attrs...) hidden_tls_proto (name, ##attrs)
 # define rtld_hidden_def(name) hidden_def (name)
Index: glibc-2.26/include/stdlib.h
===================================================================
--- glibc-2.26.orig/include/stdlib.h
+++ glibc-2.26/include/stdlib.h
@@ -287,7 +287,7 @@ struct abort_msg_s
 extern struct abort_msg_s *__abort_msg;
 libc_hidden_proto (__abort_msg)
 
-# if IS_IN (rtld)
+# if IS_IN (rtld) && !defined NO_RTLD_HIDDEN
 extern __typeof (unsetenv) unsetenv attribute_hidden;
 extern __typeof (__strtoul_internal) __strtoul_internal attribute_hidden;
 # endif
Index: glibc-2.26/sysdeps/mach/hurd/configure.ac
===================================================================
--- glibc-2.26.orig/sysdeps/mach/hurd/configure.ac
+++ glibc-2.26/sysdeps/mach/hurd/configure.ac
@@ -3,7 +3,7 @@ GLIBC_PROVIDES dnl See aclocal.m4 in the
 dnl We need this setting because of the need for PLT calls in ld.so.
 dnl See Roland's comment in
 dnl https://sourceware.org/bugzilla/show_bug.cgi?id=15605
-AC_DEFINE([NO_HIDDEN])
+AC_DEFINE([NO_RTLD_HIDDEN])
 
 if test -n "$sysheaders"; then
   OLD_CPPFLAGS=$CPPFLAGS
Index: glibc-2.26/sysdeps/mach/hurd/configure
===================================================================
--- glibc-2.26.orig/sysdeps/mach/hurd/configure
+++ glibc-2.26/sysdeps/mach/hurd/configure
@@ -1,6 +1,6 @@
 # This file is generated from configure.ac by Autoconf.  DO NOT EDIT!
 
-$as_echo "#define NO_HIDDEN 1" >>confdefs.h
+$as_echo "#define NO_RTLD_HIDDEN 1" >>confdefs.h
 
 
 if test -n "$sysheaders"; then
Index: glibc-2.26/include/assert.h
===================================================================
--- glibc-2.26.orig/include/assert.h
+++ glibc-2.26/include/assert.h
@@ -20,7 +20,7 @@ extern void __assert_fail_base (const ch
 				const char *function)
      __THROW  __attribute__ ((__noreturn__));
 
-# if IS_IN (libc) || IS_IN (rtld)
+# if IS_IN (libc) || (IS_IN (rtld) && !defined NO_RTLD_HIDDEN)
 hidden_proto (__assert_fail)
 hidden_proto (__assert_perror_fail)
 # endif
Index: glibc-2.26/include/dirent.h
===================================================================
--- glibc-2.26.orig/include/dirent.h
+++ glibc-2.26/include/dirent.h
@@ -76,7 +76,7 @@ extern __typeof (scandirat) __scandirat;
 libc_hidden_proto (__scandirat)
 libc_hidden_proto (scandirat64)
 
-#  if IS_IN (rtld)
+#  if IS_IN (rtld) && !defined NO_RTLD_HIDDEN
 extern __typeof (__closedir) __closedir attribute_hidden;
 extern __typeof (__fdopendir) __fdopendir attribute_hidden;
 extern __typeof (__readdir) __readdir attribute_hidden;
Index: glibc-2.26/include/libc-internal.h
===================================================================
--- glibc-2.26.orig/include/libc-internal.h
+++ glibc-2.26/include/libc-internal.h
@@ -49,7 +49,7 @@ extern void __libc_thread_freeres (void)
 /* Define and initialize `__progname' et. al.  */
 extern void __init_misc (int, char **, char **);
 
-# if IS_IN (rtld)
+# if IS_IN (rtld) && !defined NO_RTLD_HIDDEN
 extern __typeof (__profile_frequency) __profile_frequency attribute_hidden;
 # endif
 
Index: glibc-2.26/include/setjmp.h
===================================================================
--- glibc-2.26.orig/include/setjmp.h
+++ glibc-2.26/include/setjmp.h
@@ -25,7 +25,7 @@ libc_hidden_proto (__libc_longjmp)
 libc_hidden_proto (_setjmp)
 libc_hidden_proto (__sigsetjmp)
 
-# if IS_IN (rtld)
+# if IS_IN (rtld) && !defined NO_RTLD_HIDDEN
 extern __typeof (__sigsetjmp) __sigsetjmp attribute_hidden;
 # endif
 #endif
Index: glibc-2.26/include/signal.h
===================================================================
--- glibc-2.26.orig/include/signal.h
+++ glibc-2.26/include/signal.h
@@ -53,7 +53,7 @@ extern int __xpg_sigpause (int sig);
 /* Allocate real-time signal with highest/lowest available priority.  */
 extern int __libc_allocate_rtsig (int __high);
 
-#  if IS_IN (rtld)
+#  if IS_IN (rtld) && !defined NO_RTLD_HIDDEN
 extern __typeof (__sigaction) __sigaction attribute_hidden;
 extern __typeof (__libc_sigaction) __libc_sigaction attribute_hidden;
 #  endif
Index: glibc-2.26/include/string.h
===================================================================
--- glibc-2.26.orig/include/string.h
+++ glibc-2.26/include/string.h
@@ -142,7 +142,7 @@ libc_hidden_builtin_proto (strspn)
 libc_hidden_builtin_proto (strstr)
 libc_hidden_builtin_proto (ffs)
 
-#if IS_IN (rtld)
+#if IS_IN (rtld) && !defined NO_RTLD_HIDDEN
 extern __typeof (__stpcpy) __stpcpy attribute_hidden;
 extern __typeof (__strdup) __strdup attribute_hidden;
 extern __typeof (__strerror_r) __strerror_r attribute_hidden;
Index: glibc-2.26/include/sys/stat.h
===================================================================
--- glibc-2.26.orig/include/sys/stat.h
+++ glibc-2.26/include/sys/stat.h
@@ -12,7 +12,7 @@ extern __mode_t __umask (__mode_t __mask
 extern int __mkdir (const char *__path, __mode_t __mode);
 extern int __mknod (const char *__path,
 		    __mode_t __mode, __dev_t __dev);
-#if IS_IN (libc) || IS_IN (rtld)
+#if IS_IN (libc) || (IS_IN (rtld) && !defined NO_RTLD_HIDDEN)
 hidden_proto (__fxstat)
 hidden_proto (__fxstat64)
 hidden_proto (__lxstat)
@@ -35,7 +35,7 @@ libc_hidden_proto (__xmknodat)
 libc_hidden_proto (__fxstatat)
 libc_hidden_proto (__fxstatat64)
 
-# if IS_IN (rtld)
+# if IS_IN (rtld) && !defined NO_RTLD_HIDDEN
 extern __typeof (__fxstatat64) __fxstatat64 attribute_hidden;
 # endif
 
Index: glibc-2.26/include/sys/utsname.h
===================================================================
--- glibc-2.26.orig/include/sys/utsname.h
+++ glibc-2.26/include/sys/utsname.h
@@ -7,7 +7,7 @@ extern int __uname (struct utsname *__na
 libc_hidden_proto (uname)
 libc_hidden_proto (__uname)
 
-# if IS_IN (rtld)
+# if IS_IN (rtld) && !defined NO_RTLD_HIDDEN
 extern __typeof (__uname) __uname attribute_hidden;
 # endif
 #endif
Index: glibc-2.26/sysdeps/generic/_itoa.h
===================================================================
--- glibc-2.26.orig/sysdeps/generic/_itoa.h
+++ glibc-2.26/sysdeps/generic/_itoa.h
@@ -46,7 +46,7 @@ extern char *_itoa (unsigned long long i
 
 extern const char _itoa_upper_digits[];
 extern const char _itoa_lower_digits[];
-#if IS_IN (libc) || IS_IN (rtld)
+#if IS_IN (libc) || (IS_IN (rtld) && !defined NO_RTLD_HIDDEN)
 hidden_proto (_itoa_upper_digits)
 hidden_proto (_itoa_lower_digits)
 #endif
Index: glibc-2.26/config.h.in
===================================================================
--- glibc-2.26.orig/config.h.in
+++ glibc-2.26/config.h.in
@@ -93,6 +93,10 @@
    include/libc-symbols.h that avoid PLT slots in the shared objects.  */
 #undef	NO_HIDDEN
 
+/* Define this to disable in rtld the 'hidden_proto' et al macros in
+   include/libc-symbols.h that avoid PLT slots in the shared objects.  */
+#undef	NO_RTLD_HIDDEN
+
 /* Define this to disable lazy relocations in DSOs.  */
 #undef	BIND_NOW