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

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

Hello,

So no objection against doing this, so we get rid of general NO_HIDDEN
support by implementing just NO_RTLD_HIDDEN?

Samuel

Samuel Thibault, on mar. 19 sept. 2017 01:51:45 +0200, wrote:
> 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
>  

-- 
Samuel
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