Move libc_freeres_ptrs and libc_subfreeres to hidden/weak functions

They are both used by __libc_freeres to free all library malloc
allocated resources to help tooling like mtrace or valgrind with
memory leak tracking.

The current scheme uses assembly markers and linker script entries
to consolidate the free routine function pointers in the RELRO segment
and to be freed buffers in BSS.

This patch changes it to use specific free functions for
libc_freeres_ptrs buffers and call the function pointer array directly
with call_function_static_weak.

It allows the removal of both the internal macros and the linker
script sections.

Checked on x86_64-linux-gnu, i686-linux-gnu, and aarch64-linux-gnu.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>

8 files changed, 15 insertions, 14 deletions

diff --git a/nss/getXXbyYY.c b/nss/getXXbyYY.c
index 0c473a4..efb17f0 100644
--- a/nss/getXXbyYY.c
+++ b/nss/getXXbyYY.c
@@ -20,6 +20,7 @@
 #include <libc-lock.h>
 #include <stdlib.h>
 #include <resolv.h>
+#include <set-freeres.h>
 
 #include "nsswitch.h"
 
@@ -58,6 +59,9 @@
 #define APPEND_R1(name) name##_r
 #define INTERNAL(name) INTERNAL1 (name)
 #define INTERNAL1(name) __##name
+#define APPEND_FREEMEM_NAME1(name) __libc_##name##_freemem_ptr
+#define APPEND_FREEMEM_NAME(name) APPEND_FREEMEM_NAME1(name)
+#define FREEMEM_NAME APPEND_FREEMEM_NAME (FUNCTION_NAME)
 
 /* Sometimes we need to store error codes in the `h_errno' variable.  */
 #ifdef NEED_H_ERRNO
@@ -86,8 +90,9 @@ extern int INTERNAL (REENTRANT_NAME) (ADD_PARAMS, LOOKUP_TYPE *resbuf,
 __libc_lock_define_initialized (static, lock);
 
 /* This points to the static buffer used.  */
-libc_freeres_ptr (static char *buffer);
+static char *buffer;
 
+weak_alias (buffer, FREEMEM_NAME)
 
 LOOKUP_TYPE *
 FUNCTION_NAME (ADD_PARAMS)
diff --git a/nss/getXXent.c b/nss/getXXent.c
index 7ac8379..8acb6dc 100644
--- a/nss/getXXent.c
+++ b/nss/getXXent.c
@@ -18,6 +18,7 @@
 #include <errno.h>
 #include <libc-lock.h>
 #include <stdlib.h>
+#include <set-freeres.h>
 
 #include "nsswitch.h"
 
@@ -43,6 +44,9 @@
 #define APPEND_R1(name) name##_r
 #define INTERNAL(name) INTERNAL1 (name)
 #define INTERNAL1(name) __##name
+#define APPEND_FREEMEM_NAME1(name) __libc_##name##_freemem_ptr
+#define APPEND_FREEMEM_NAME(name) APPEND_FREEMEM_NAME1(name)
+#define FREEMEM_NAME APPEND_FREEMEM_NAME (GETFUNC_NAME)
 
 /* Sometimes we need to store error codes in the `h_errno' variable.  */
 #ifdef NEED_H_ERRNO
@@ -62,8 +66,9 @@ extern int INTERNAL (REENTRANT_GETNAME) (LOOKUP_TYPE *resbuf, char *buffer,
 __libc_lock_define_initialized (static, lock);
 
 /* This points to the static buffer used.  */
-libc_freeres_ptr (static char *buffer);
+static char *buffer;
 
+weak_alias (buffer, FREEMEM_NAME)
 
 LOOKUP_TYPE *
 GETFUNC_NAME (void)
diff --git a/nss/nss_action.c b/nss/nss_action.c
index 8ca7254..447c219 100644
--- a/nss/nss_action.c
+++ b/nss/nss_action.c
@@ -102,7 +102,7 @@ __nss_action_allocate (struct nss_action *actions, size_t count)
   return result;
 }
 
-void __libc_freeres_fn_section
+void
 __nss_action_freeres (void)
 {
   struct nss_action_list_wrapper *current = nss_actions;
diff --git a/nss/nss_action.h b/nss/nss_action.h
index edd84b8..7ab2415 100644
--- a/nss/nss_action.h
+++ b/nss/nss_action.h
@@ -101,8 +101,5 @@ nss_action_list __nss_action_allocate (struct nss_action *actions,
    EINVAL means that LINE is syntactically invalid.  */
 nss_action_list __nss_action_parse (const char *line);
 
-/* Called from __libc_freeres.  */
-void __nss_action_freeres (void) attribute_hidden;
-
 
 #endif /* _NSS_ACTION_H */
diff --git a/nss/nss_database.c b/nss/nss_database.c
index 3350346..2edcab4 100644
--- a/nss/nss_database.c
+++ b/nss/nss_database.c
@@ -495,7 +495,7 @@ __nss_database_get_noreload (enum nss_database db)
   return result;
 }
 
-void __libc_freeres_fn_section
+void
 __nss_database_freeres (void)
 {
   free (global_database_state);
diff --git a/nss/nss_database.h b/nss/nss_database.h
index 2462030..1a17261 100644
--- a/nss/nss_database.h
+++ b/nss/nss_database.h
@@ -64,9 +64,6 @@ libc_hidden_proto (__nss_database_get)
 nss_action_list __nss_database_get_noreload (enum nss_database db)
   attribute_hidden;
 
-/* Called from __libc_freeres.  */
-void __nss_database_freeres (void) attribute_hidden;
-
 /* Internal type.  Exposed only for fork handling purposes.  */
 struct nss_database_data
 {
diff --git a/nss/nss_module.c b/nss/nss_module.c
index 8815fef..487e513 100644
--- a/nss/nss_module.c
+++ b/nss/nss_module.c
@@ -416,7 +416,7 @@ __nss_module_disable_loading (void)
   __libc_lock_unlock (nss_module_list_lock);
 }
 
-void __libc_freeres_fn_section
+void
 __nss_module_freeres (void)
 {
   struct nss_module *current = nss_module_list;
diff --git a/nss/nss_module.h b/nss/nss_module.h
index eda0ebc..fb30fb8 100644
--- a/nss/nss_module.h
+++ b/nss/nss_module.h
@@ -100,7 +100,4 @@ void *__nss_module_get_function (struct nss_module *module, const char *name)
 /* Block attempts to dlopen any module we haven't already opened.  */
 void __nss_module_disable_loading (void);
 
-/* Called from __libc_freeres.  */
-void __nss_module_freeres (void) attribute_hidden;
-
 #endif /* NSS_MODULE_H */