diff mbox

Mark internal functions with attribute_hidden

Message ID 20170817122549.GA15116@gmail.com
State New, archived
Headers show

Commit Message

H.J. Lu Aug. 17, 2017, 12:25 p.m. UTC
Mark internal functions with attribute_hidden to allow direct access to
internal functions within libc.a without using GOT when the compiler
defaults to -fPIE.

Any comments?

H.J.
---
	* iconv/gconv_int.h (__gconv_open): Add attribute_hidden.
	(__gconv_close): Likewise.
	(__gconv): Likewise.
	(__gconv_find_transform): Likewise.
	(__gconv_lookup_cache): Likewise.
	(__gconv_compare_alias_cache): Likewise.
	(__gconv_load_cache): Likewise.
	(__gconv_get_path): Likewise.
	(__gconv_close_transform): Likewise.
	(__gconv_release_cache): Likewise.
	(__gconv_find_shlib): Likewise.
	(__gconv_release_shlib): Likewise.
	(__gconv_get_builtin_trans): Likewise.
	(__gconv_compare_alias): Likewise.
	* include/dlfcn.h (_dlerror_run): Likewise.
	* include/stdio.h (__fortify_fail_abort): Likewise.
	* include/time.h (__tz_compute): Likewise.
	(__strptime_internal): Likewise.
	* intl/gettextP.h (_nl_find_domain): Likewise.
	(_nl_load_domain): Likewise.
	(_nl_find_msg): Likewise.
	* intl/plural-exp.h (FREE_EXPRESSION): Likewise.
	(EXTRACT_PLURAL_EXPRESSION): Likewise.
	* locale/coll-lookup.h (__collidx_table_lookup): Likewise.
	* resolv/gai_misc.h (__gai_enqueue_request): Likewise.
	(__gai_find_request): Likewise.
	(__gai_remove_request): Likewise.
	(__gai_notify): Likewise.
	(__gai_notify_only): Likewise.
	* sysdeps/generic/aio_misc.h (__aio_sigqueue): Likewise.
	* sysdeps/generic/ldsodefs.h (_dl_symbol_value): Likewise.
	(_dl_fini): Likewise.
	(_dl_non_dynamic_init): Likewise.
	(_dl_aux_init): Likewise.
	* sysdeps/i386/machine-gmon.h (mcount_internal): Likewise.
	* sysdeps/unix/sysv/linux/i386/olddirent.h (__old_getdents64):
	Likewise.
	* wcsmbs/wcsmbsload.h (__wcsmbs_load_conv): Likewise.
	(__wcsmbs_clone_conv): Likewise.
	(__wcsmbs_named_conv): Likewise.
---
 iconv/gconv_int.h                        | 31 ++++++++++++++++---------------
 include/dlfcn.h                          |  2 +-
 include/stdio.h                          |  2 +-
 include/time.h                           |  4 ++--
 intl/gettextP.h                          |  8 ++++----
 intl/plural-exp.h                        |  4 ++--
 locale/coll-lookup.h                     |  4 ++--
 resolv/gai_misc.h                        | 10 +++++-----
 sysdeps/generic/aio_misc.h               |  2 +-
 sysdeps/generic/ldsodefs.h               | 10 ++++++----
 sysdeps/i386/machine-gmon.h              |  2 +-
 sysdeps/unix/sysv/linux/i386/olddirent.h |  2 +-
 wcsmbs/wcsmbsload.h                      |  6 +++---
 13 files changed, 45 insertions(+), 42 deletions(-)

Comments

Florian Weimer Aug. 17, 2017, 12:37 p.m. UTC | #1
On 08/17/2017 02:25 PM, H.J. Lu wrote:
> Mark internal functions with attribute_hidden to allow direct access to
> internal functions within libc.a without using GOT when the compiler
> defaults to -fPIE.

This explanation is a bit confusing.  I think this benefits other
architectures, too.

I have an internal_function removal patch which conflicts with this, but
I can adjust it.

Thanks,
Florian
H.J. Lu Aug. 17, 2017, 12:43 p.m. UTC | #2
On Thu, Aug 17, 2017 at 5:37 AM, Florian Weimer <fweimer@redhat.com> wrote:
> On 08/17/2017 02:25 PM, H.J. Lu wrote:
>> Mark internal functions with attribute_hidden to allow direct access to
>> internal functions within libc.a without using GOT when the compiler
>> defaults to -fPIE.
>
> This explanation is a bit confusing.  I think this benefits other
> architectures, too.

Yes, this is target independent.   It should benefit static PIE build for all
targets.  On x86, it bypasses GOT/PLT.

> I have an internal_function removal patch which conflicts with this, but
> I can adjust it.
>
Zack Weinberg Aug. 17, 2017, 1:12 p.m. UTC | #3
On Thu, Aug 17, 2017 at 8:43 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
> On Thu, Aug 17, 2017 at 5:37 AM, Florian Weimer <fweimer@redhat.com> wrote:
>> On 08/17/2017 02:25 PM, H.J. Lu wrote:
>>> Mark internal functions with attribute_hidden to allow direct access to
>>> internal functions within libc.a without using GOT when the compiler
>>> defaults to -fPIE.
>>
>> This explanation is a bit confusing.  I think this benefits other
>> architectures, too.
>
> Yes, this is target independent.   It should benefit static PIE build for all
> targets.  On x86, it bypasses GOT/PLT.

Should internal_function just imply attribute_hidden?  Or is this
inappropriate for some things marked internal_function?

zw
H.J. Lu Aug. 17, 2017, 1:19 p.m. UTC | #4
On Thu, Aug 17, 2017 at 6:12 AM, Zack Weinberg <zackw@panix.com> wrote:
> On Thu, Aug 17, 2017 at 8:43 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
>> On Thu, Aug 17, 2017 at 5:37 AM, Florian Weimer <fweimer@redhat.com> wrote:
>>> On 08/17/2017 02:25 PM, H.J. Lu wrote:
>>>> Mark internal functions with attribute_hidden to allow direct access to
>>>> internal functions within libc.a without using GOT when the compiler
>>>> defaults to -fPIE.
>>>
>>> This explanation is a bit confusing.  I think this benefits other
>>> architectures, too.
>>
>> Yes, this is target independent.   It should benefit static PIE build for all
>> targets.  On x86, it bypasses GOT/PLT.
>
> Should internal_function just imply attribute_hidden?  Or is this
> inappropriate for some things marked internal_function?
>

No, we can't do that since internal_function is used on both internal
functions within libc as well as private functions between different
shared libraries.   internal_function controls how function parameters
are passed on i386.
Florian Weimer Aug. 17, 2017, 1:34 p.m. UTC | #5
On 08/17/2017 03:12 PM, Zack Weinberg wrote:
> On Thu, Aug 17, 2017 at 8:43 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
>> On Thu, Aug 17, 2017 at 5:37 AM, Florian Weimer <fweimer@redhat.com> wrote:
>>> On 08/17/2017 02:25 PM, H.J. Lu wrote:
>>>> Mark internal functions with attribute_hidden to allow direct access to
>>>> internal functions within libc.a without using GOT when the compiler
>>>> defaults to -fPIE.
>>>
>>> This explanation is a bit confusing.  I think this benefits other
>>> architectures, too.
>>
>> Yes, this is target independent.   It should benefit static PIE build for all
>> targets.  On x86, it bypasses GOT/PLT.
> 
> Should internal_function just imply attribute_hidden?  Or is this
> inappropriate for some things marked internal_function?

I want to remove internal_function completely because it serves no
useful purpose whatsoever because it has never been used consistently.
Currently, it expands to an empty string on all builds.

Thanks,
Florian
Joseph Myers Aug. 17, 2017, 2:01 p.m. UTC | #6
On Thu, 17 Aug 2017, H.J. Lu wrote:

> Yes, this is target independent.   It should benefit static PIE build for all
> targets.  On x86, it bypasses GOT/PLT.

Specifically, on x86 I'd consider this (making functions hidden if they 
are not exported from the shared library containing their definitions) to 
be part of the fix for bug 18822.
diff mbox

Patch

diff --git a/iconv/gconv_int.h b/iconv/gconv_int.h
index 85a67ad31b..52b8aad020 100644
--- a/iconv/gconv_int.h
+++ b/iconv/gconv_int.h
@@ -157,11 +157,11 @@  __libc_lock_define (extern, __gconv_lock attribute_hidden)
 /* Return in *HANDLE decriptor for transformation from FROMSET to TOSET.  */
 extern int __gconv_open (const char *toset, const char *fromset,
 			 __gconv_t *handle, int flags)
-     internal_function;
+     internal_function attribute_hidden;
 
 /* Free resources associated with transformation descriptor CD.  */
 extern int __gconv_close (__gconv_t cd)
-     internal_function;
+     internal_function attribute_hidden;
 
 /* Transform at most *INBYTESLEFT bytes from buffer starting at *INBUF
    according to rules described by CD and place up to *OUTBYTESLEFT
@@ -170,36 +170,37 @@  extern int __gconv_close (__gconv_t cd)
 extern int __gconv (__gconv_t cd, const unsigned char **inbuf,
 		    const unsigned char *inbufend, unsigned char **outbuf,
 		    unsigned char *outbufend, size_t *irreversible)
-     internal_function;
+     internal_function attribute_hidden;
 
 /* Return in *HANDLE a pointer to an array with *NSTEPS elements describing
    the single steps necessary for transformation from FROMSET to TOSET.  */
 extern int __gconv_find_transform (const char *toset, const char *fromset,
 				   struct __gconv_step **handle,
 				   size_t *nsteps, int flags)
-     internal_function;
+     internal_function attribute_hidden;
 
 /* Search for transformation in cache data.  */
 extern int __gconv_lookup_cache (const char *toset, const char *fromset,
 				 struct __gconv_step **handle, size_t *nsteps,
 				 int flags)
-     internal_function;
+     internal_function attribute_hidden;
 
 /* Compare the two name for whether they are after alias expansion the
    same.  This function uses the cache and fails if none is
    loaded.  */
 extern int __gconv_compare_alias_cache (const char *name1, const char *name2,
-					int *result) internal_function;
+					int *result)
+     internal_function attribute_hidden;
 
 /* Free data associated with a step's structure.  */
 extern void __gconv_release_step (struct __gconv_step *step)
-     internal_function;
+     internal_function attribute_hidden;
 
 /* Read all the configuration data and cache it.  */
 extern void __gconv_read_conf (void) attribute_hidden;
 
 /* Try to read module cache file.  */
-extern int __gconv_load_cache (void) internal_function;
+extern int __gconv_load_cache (void) internal_function attribute_hidden;
 
 /* Retrieve pointer to internal cache.  */
 extern void *__gconv_get_cache (void);
@@ -211,7 +212,7 @@  extern struct gconv_module *__gconv_get_modules_db (void);
 extern void *__gconv_get_alias_db (void);
 
 /* Determine the directories we are looking in.  */
-extern void __gconv_get_path (void) internal_function;
+extern void __gconv_get_path (void) internal_function attribute_hidden;
 
 /* Comparison function to search alias.  */
 extern int __gconv_alias_compare (const void *p1, const void *p2)
@@ -221,33 +222,33 @@  extern int __gconv_alias_compare (const void *p1, const void *p2)
    cause the code to be unloaded.  */
 extern int __gconv_close_transform (struct __gconv_step *steps,
 				    size_t nsteps)
-     internal_function;
+     internal_function attribute_hidden;
 
 /* Free all resources allocated for the transformation record when
    using the cache.  */
 extern void __gconv_release_cache (struct __gconv_step *steps, size_t nsteps)
-     internal_function;
+     internal_function attribute_hidden;
 
 /* Load shared object named by NAME.  If already loaded increment reference
    count.  */
 extern struct __gconv_loaded_object *__gconv_find_shlib (const char *name)
-     internal_function;
+     internal_function attribute_hidden;
 
 /* Release shared object.  If no further reference is available unload
    the object.  */
 extern void __gconv_release_shlib (struct __gconv_loaded_object *handle)
-     internal_function;
+     internal_function attribute_hidden;
 
 /* Fill STEP with information about builtin module with NAME.  */
 extern void __gconv_get_builtin_trans (const char *name,
 				       struct __gconv_step *step)
-     internal_function;
+     internal_function attribute_hidden;
 
 libc_hidden_proto (__gconv_transliterate)
 
 /* If NAME is an codeset alias expand it.  */
 extern int __gconv_compare_alias (const char *name1, const char *name2)
-     internal_function;
+     internal_function attribute_hidden;
 
 
 /* Builtin transformations.  */
diff --git a/include/dlfcn.h b/include/dlfcn.h
index 51cc1dfde8..6aad074e8e 100644
--- a/include/dlfcn.h
+++ b/include/dlfcn.h
@@ -75,7 +75,7 @@  extern void *_dl_vsym (void *handle, const char *name, const char *version,
    arranges for `dlerror' to return the error details.
    ARGS is passed as argument to OPERATE.  */
 extern int _dlerror_run (void (*operate) (void *), void *args)
-     internal_function;
+    internal_function attribute_hidden;
 
 #ifdef SHARED
 # define DL_CALLER_DECL /* Nothing */
diff --git a/include/stdio.h b/include/stdio.h
index 509447c528..5c0ef8ed24 100644
--- a/include/stdio.h
+++ b/include/stdio.h
@@ -100,7 +100,7 @@  extern void __libc_message (enum __libc_message_action action,
 			    const char *__fnt, ...);
 extern void __fortify_fail (const char *msg) __attribute__ ((__noreturn__));
 extern void __fortify_fail_abort (_Bool, const char *msg)
-  __attribute__ ((__noreturn__));
+  __attribute__ ((__noreturn__)) attribute_hidden;
 libc_hidden_proto (__fortify_fail)
 libc_hidden_proto (__fortify_fail_abort)
 
diff --git a/include/time.h b/include/time.h
index 9956b82eb8..958cb8600d 100644
--- a/include/time.h
+++ b/include/time.h
@@ -46,7 +46,7 @@  extern void __tzfile_default (const char *std, const char *dst,
 			      long int stdoff, long int dstoff);
 extern void __tzset_parse_tz (const char *tz);
 extern void __tz_compute (time_t timer, struct tm *tm, int use_localtime)
-     __THROW internal_function;
+     __THROW internal_function attribute_hidden;
 
 /* Subroutine of `mktime'.  Return the `time_t' representation of TP and
    normalize TP, given that a `struct tm *' maps to a `time_t' as performed
@@ -93,7 +93,7 @@  extern int __getclktck (void);
 extern char * __strptime_internal (const char *rp, const char *fmt,
 				   struct tm *tm, void *statep,
 				   locale_t locparam)
-     internal_function;
+     internal_function attribute_hidden;
 
 extern double __difftime (time_t time1, time_t time0);
 
diff --git a/intl/gettextP.h b/intl/gettextP.h
index eeb8970852..f88cd782ab 100644
--- a/intl/gettextP.h
+++ b/intl/gettextP.h
@@ -256,22 +256,22 @@  extern const char *_nl_locale_name_default (void);
 struct loaded_l10nfile *_nl_find_domain (const char *__dirname, char *__locale,
 					 const char *__domainname,
 					 struct binding *__domainbinding)
-     internal_function;
+     internal_function attribute_hidden;
 void _nl_load_domain (struct loaded_l10nfile *__domain,
 		      struct binding *__domainbinding)
-     internal_function;
+     internal_function attribute_hidden;
 
 #ifdef IN_LIBGLOCALE
 char *_nl_find_msg (struct loaded_l10nfile *domain_file,
 		    struct binding *domainbinding, const char *encoding,
 		    const char *msgid,
 		    size_t *lengthp)
-     internal_function;
+     internal_function attribute_hidden;
 #else
 char *_nl_find_msg (struct loaded_l10nfile *domain_file,
 		    struct binding *domainbinding, const char *msgid,
 		    int convert, size_t *lengthp)
-     internal_function;
+     internal_function attribute_hidden;
 #endif
 
 /* The internal variables in the standalone libintl.a must have different
diff --git a/intl/plural-exp.h b/intl/plural-exp.h
index 144aa1ed4b..af6c9b9c49 100644
--- a/intl/plural-exp.h
+++ b/intl/plural-exp.h
@@ -106,13 +106,13 @@  struct parse_args
 #endif
 
 extern void FREE_EXPRESSION (struct expression *exp)
-     internal_function;
+     internal_function attribute_hidden;
 extern int PLURAL_PARSE (struct parse_args *arg);
 extern const struct expression GERMANIC_PLURAL attribute_hidden;
 extern void EXTRACT_PLURAL_EXPRESSION (const char *nullentry,
 				       const struct expression **pluralp,
 				       unsigned long int *npluralsp)
-     internal_function;
+     internal_function attribute_hidden;
 
 #if !defined (_LIBC) && !defined (IN_LIBINTL) && !defined (IN_LIBGLOCALE)
 extern unsigned long int plural_eval (const struct expression *pexp,
diff --git a/locale/coll-lookup.h b/locale/coll-lookup.h
index d95408ad68..55a0b59236 100644
--- a/locale/coll-lookup.h
+++ b/locale/coll-lookup.h
@@ -20,8 +20,8 @@ 
 
 /* Lookup in a table of int32_t, with default value 0.  */
 extern int32_t __collidx_table_lookup (const char *table, uint32_t wc)
-     internal_function;
+     internal_function attribute_hidden;
 
 /* Lookup in a table of uint32_t, with default value 0xffffffff.  */
 extern uint32_t __collseq_table_lookup (const char *table, uint32_t wc)
-     internal_function;
+     internal_function attribute_hidden;
diff --git a/resolv/gai_misc.h b/resolv/gai_misc.h
index 6679d2b7d5..01b2f89738 100644
--- a/resolv/gai_misc.h
+++ b/resolv/gai_misc.h
@@ -76,23 +76,23 @@  extern pthread_mutex_t __gai_requests_mutex;
 
 /* Enqueue request.  */
 extern struct requestlist *__gai_enqueue_request (struct gaicb *gaicbp)
-     internal_function;
+     internal_function attribute_hidden;
 
 /* Find request on wait list.  */
 extern struct requestlist *__gai_find_request (const struct gaicb *gaicbp)
-     internal_function;
+     internal_function attribute_hidden;
 
 /* Remove request from waitlist.  */
 extern int __gai_remove_request (struct gaicb *gaicbp)
-     internal_function;
+     internal_function attribute_hidden;
 
 /* Notify initiator of request and tell this everybody listening.  */
 extern void __gai_notify (struct requestlist *req)
-     internal_function;
+     internal_function attribute_hidden;
 
 /* Notify initiator of request.  */
 extern int __gai_notify_only (struct sigevent *sigev, pid_t caller_pid)
-     internal_function;
+     internal_function attribute_hidden;
 
 /* Send the signal.  */
 extern int __gai_sigqueue (int sig, const union sigval val, pid_t caller_pid)
diff --git a/sysdeps/generic/aio_misc.h b/sysdeps/generic/aio_misc.h
index a941a68aaa..e2264ba2d4 100644
--- a/sysdeps/generic/aio_misc.h
+++ b/sysdeps/generic/aio_misc.h
@@ -41,7 +41,7 @@  typedef union
 
 /* Send the signal.  */
 extern int __aio_sigqueue (int sig, const union sigval val, pid_t caller_pid)
-     internal_function;
+     internal_function attribute_hidden;
 
 
 #endif /* aio_misc.h */
diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h
index 49e673dd24..e4004eee78 100644
--- a/sysdeps/generic/ldsodefs.h
+++ b/sysdeps/generic/ldsodefs.h
@@ -912,7 +912,7 @@  extern lookup_t _dl_lookup_symbol_x (const char *undef,
 
 /* Look up symbol NAME in MAP's scope and return its run-time address.  */
 extern ElfW(Addr) _dl_symbol_value (struct link_map *map, const char *name)
-     internal_function;
+     internal_function attribute_hidden;
 
 /* Add the new link_map NEW to the end of the namespace list.  */
 extern void _dl_add_to_namespace_list (struct link_map *new, Lmid_t nsid)
@@ -968,7 +968,7 @@  extern void _dl_init (struct link_map *main_map, int argc, char **argv,
 
 /* Call the finalizer functions of all shared objects whose
    initializer functions have completed.  */
-extern void _dl_fini (void);
+extern void _dl_fini (void) attribute_hidden;
 
 /* Sort array MAPS according to dependencies of the contained objects.  */
 extern void _dl_sort_fini (struct link_map **maps, size_t nmaps, char *used,
@@ -1147,10 +1147,12 @@  extern struct link_map *_dl_find_dso_for_object (const ElfW(Addr) addr);
 rtld_hidden_proto (_dl_find_dso_for_object)
 
 /* Initialization which is normally done by the dynamic linker.  */
-extern void _dl_non_dynamic_init (void) internal_function;
+extern void _dl_non_dynamic_init (void)
+     internal_function attribute_hidden;
 
 /* Used by static binaries to check the auxiliary vector.  */
-extern void _dl_aux_init (ElfW(auxv_t) *av) internal_function;
+extern void _dl_aux_init (ElfW(auxv_t) *av)
+     internal_function attribute_hidden;
 
 
 __END_DECLS
diff --git a/sysdeps/i386/machine-gmon.h b/sysdeps/i386/machine-gmon.h
index 3e90b8c0c7..81e168e4e6 100644
--- a/sysdeps/i386/machine-gmon.h
+++ b/sysdeps/i386/machine-gmon.h
@@ -30,7 +30,7 @@ 
 #define mcount_internal __mcount_internal
 
 extern void mcount_internal (u_long frompc, u_long selfpc)
-  __attribute__ ((regparm (2)));
+  __attribute__ ((regparm (2))) attribute_hidden;
 
 #define _MCOUNT_DECL(frompc, selfpc)                \
   __attribute__ ((regparm (2)))			    \
diff --git a/sysdeps/unix/sysv/linux/i386/olddirent.h b/sysdeps/unix/sysv/linux/i386/olddirent.h
index 413f78d108..4875a1f2fa 100644
--- a/sysdeps/unix/sysv/linux/i386/olddirent.h
+++ b/sysdeps/unix/sysv/linux/i386/olddirent.h
@@ -34,7 +34,7 @@  extern struct __old_dirent64 *__old_readdir64 (DIR *__dirp);
 extern int __old_readdir64_r (DIR *__dirp, struct __old_dirent64 *__entry,
 			  struct __old_dirent64 **__result);
 extern __ssize_t __old_getdents64 (int __fd, char *__buf, size_t __nbytes)
-	internal_function;
+	internal_function attribute_hidden;
 int __old_scandir64 (const char * __dir,
 		     struct __old_dirent64 *** __namelist,
 		     int (*__selector) (const struct __old_dirent64 *),
diff --git a/wcsmbs/wcsmbsload.h b/wcsmbs/wcsmbsload.h
index 3e254a877e..eb2a2bea33 100644
--- a/wcsmbs/wcsmbsload.h
+++ b/wcsmbs/wcsmbsload.h
@@ -38,15 +38,15 @@  extern const struct gconv_fcts __wcsmbs_gconv_fcts_c attribute_hidden;
 
 /* Load conversion functions for the currently selected locale.  */
 extern void __wcsmbs_load_conv (struct __locale_data *new_category)
-     internal_function;
+     internal_function attribute_hidden;
 
 /* Clone the current `__wcsmbs_load_conv' value.  */
 extern void __wcsmbs_clone_conv (struct gconv_fcts *copy)
-     internal_function;
+     internal_function attribute_hidden;
 
 /* Find the conversion functions for converting to and from NAME.  */
 extern int __wcsmbs_named_conv (struct gconv_fcts *copy, const char *name)
-     internal_function;
+     internal_function attribute_hidden;
 
 /* Function used for the `private.cleanup' hook.  */
 extern void _nl_cleanup_ctype (struct __locale_data *)