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

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

Samuel Thibault, on dim. 24 sept. 2017 18:22:05 +0200, wrote:
> So no objection against doing this, so we get rid of general NO_HIDDEN
> support by implementing just NO_RTLD_HIDDEN?

I have pushed it.

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
> <s> on se croirait en cool : Some browsers close comments on the first ">" character, so to hide script content from such browsers, you can transpose operands for relational and shift operators (e.g., use "y < x" rather than "x > y") or use scripting language-dependent escapes for ">".
>  -+- #ens-mim -+-

-- 
Samuel
<macavity> bash: ls: Computer bought the farm
<macavity> THAT frightens ppl! :P
<macavity> id rather see: "bash: ls: Initialization of googol(AWAX)
        disengaged in HYPER32/64 mode due to faulty page request at
        AX:12A34F84B"
<macavity> at least that would give me the feeling that the
        *programmers* knows what is going on :P
(lovely Hurd...)