libc: Extend __libc_freeres framework (Bug 23329).

The __libc_freeres framework does not extend to non-libc.so objects.
This causes problems in general for valgrind and mtrace detecting
unfreed objects in both libdl.so and libpthread.so.  This change is
a pre-requisite to properly moving the malloc hooks out of malloc
since such a move now requires precise accounting of all allocated
data before destructors are run.

This commit adds a proper hook in libc.so.6 for both libdl.so and
for libpthread.so, this ensures that shm-directory.c which uses
freeit () to free memory is called properly.  We also remove the
nptl_freeres hook and fall back to using weak-ref-and-check idiom
for a loaded libpthread.so, thus making this process similar for
all DSOs.

Lastly we follow best practice and use explicit free calls for
both libdl.so and libpthread.so instead of the generic hook process
which has undefined order.

Tested on x86_64 with no regressions.

Signed-off-by: DJ Delorie <dj@redhat.com>
Signed-off-by: Carlos O'Donell <carlos@redhat.com>

ChangeLog

@@ -1,3 +1,51 @@
+2018-06-29  DJ Delorie  <dj@redhat.com>
+	    Carlos O'Donell  <carlos@redhat.com>
+
+	[BZ #23329]
+	* include/libc-symbols.h: Comment the freeres framework.
+	* include/set-hooks.h: Include libc-symbols.h.  Fix comment.
+	* dlfcn/Makefile (libdl-routines): Add dlfreeres.
+	* dlfcn/Versions (GLIBC_PRIVATE): Add __libdl_freeres.
+	* dlfcn/dlerror.c: Include libc-symbols.h
+	(__dlerror_main_freeres): New function.
+	* dlfcn/dlfreeres.c: New file.
+	* dlfcn/sdlfreeres.c: New file.
+	* include/dlfcn.h: Declare __dlerror_main_freeres.
+	* malloc/set-freeres.c: Declare __libdl_freeres, and
+	__libpthread_freeres.
+	(__libc_subfreeres): Call __libdl_freeres, and __libpthread_freeres if
+	the releavant libraries are loaded.
+	* malloc/thread-freeres.c: Add comments.
+	* nptl/Makefile (libpthread-routines): Add nptlfreeres.
+	* nptl/Version (GLIBC_PRIVATE): Add __libpthread_freeres.
+	* nptl/allocatestack.c (__nptl_free_stacks): New function.
+	(__free_stacks): Rename to...
+	(free_stacks): ...this. Mark static.
+	(queue_stack): Call free_stacks.
+	* nptl/libc_pthread_init.c [SHARED] (freeres_libpthread): Delete.
+	* nptl/nptl-init.c: Delete delcaration of nptl_freeres.
+	* sysdeps/nptl/pthread-functions.h (pthread_functions): Remove
+	ptr_freeres element from struct.
+	(pthread_functions): Remove .ptr_freeres from struct initializer.
+	[SHARED] (nptl_freeres): Remove.
+	* nptl/nptlfreeres.c: New file.
+	* nptl/pthreadP.h
+	[IS_IN (libpthread) && SHARED ] (__unwind_freeres): Rename to...
+	[IS_IN (libpthread)] (__nptl_unwind_freeres): ...this.  Mark
+	attribute_hidden.
+	(__free_stacks): Rename to...
+	(__nptl_stacks_freeres): ...this.
+	(__shm_directory_freeres): Declare.
+	* nptl/unwind-forcedunwind.c (__unwind_freeres): Rename to...
+	(__nptl_unwind_freeres): ...this.
+	* resolv/res-close.c: Add comment.
+	* resolv/resolv_conf.c: Include libc-symbols.h.
+	* string/strerror_l.c: Include libc-symbols.h.
+	* sunrpc/rpc_thread.c: Include libc-symbols.h.
+	* sysdeps/mach/strerror_l.c: Inlcude libc-symbols.h
+	* sysdeps/unix/sysv/linux/shm-directory.c (freeit): Rename to...
+	[IS_IN (libpthread)] (__shm_directory_freeres): ...this.
+
 2018-06-29  Rajalakshmi Srinivasaraghavan  <raji@linux.vnet.ibm.com>
 
 	* stdlib/tst-strfmon_l.c: Add tests for long double.

dlfcn/Makefile

@@ -22,7 +22,7 @@ include ../Makeconfig
 headers		:= bits/dlfcn.h dlfcn.h
 extra-libs	:= libdl
 libdl-routines	:= dlopen dlclose dlsym dlvsym dlerror dladdr dladdr1 dlinfo \
-		   dlmopen dlfcn
+		   dlmopen dlfcn dlfreeres
 routines	:= $(patsubst %,s%,$(filter-out dlfcn,$(libdl-routines)))
 elide-routines.os := $(routines)
 

dlfcn/Versions

@@ -13,5 +13,6 @@ libdl {
   }
   GLIBC_PRIVATE {
     _dlfcn_hook;
+    __libdl_freeres;
   }
 }

dlfcn/dlerror.c

@@ -24,6 +24,7 @@
 #include <string.h>
 #include <libc-lock.h>
 #include <ldsodefs.h>
+#include <libc-symbols.h>
 
 #if !defined SHARED && IS_IN (libdl)
 
@@ -222,6 +223,19 @@ free_key_mem (void *mem)
 
 # ifdef SHARED
 
+/* Free the dlerror-related resources.  */
+void
+__dlerror_main_freeres (void)
+{
+  void *mem;
+  /* Free the global memory if used.  */
+  check_free (&last_result);
+  /* Free the TSD memory if used.  */
+  mem = __libc_getspecific (key);
+  if (mem != NULL)
+    free_key_mem (mem);
+}
+
 struct dlfcn_hook *_dlfcn_hook __attribute__((nocommon));
 libdl_hidden_data_def (_dlfcn_hook)
 

dlfcn/dlfreeres.c

@@ -0,0 +1,29 @@
+/* Clean up allocated libdl memory on demand.
+   Copyright (C) 2018 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <set-hooks.h>
+#include <libc-symbols.h>
+#include <dlfcn.h>
+
+/* Free libdl.so resources.
+   Note: Caller ensures we are called only once.  */
+void
+__libdl_freeres (void)
+{
+  call_function_static_weak (__dlerror_main_freeres);
+}

dlfcn/sdlfreeres.c

@@ -0,0 +1 @@
+#include "dlfreeres.c"

include/dlfcn.h

@@ -155,6 +155,8 @@ extern void __libc_register_dl_open_hook (struct link_map *map)
 extern void __libc_register_dlfcn_hook (struct link_map *map)
      attribute_hidden;
 #endif
-#endif
+
+extern void __dlerror_main_freeres (void) attribute_hidden;
 
 #endif
+#endif

include/libc-symbols.h

@@ -217,16 +217,6 @@
   static const char __evoke_link_warning_##symbol[]	\
     __attribute__ ((used, section (".gnu.warning." #symbol __sec_comment))) \
     = msg;
-#define libc_freeres_ptr(decl) \
-  __make_section_unallocated ("__libc_freeres_ptrs, \"aw\", %nobits") \
-  decl __attribute__ ((section ("__libc_freeres_ptrs" __sec_comment)))
-#define __libc_freeres_fn_section \
-  __attribute__ ((section ("__libc_freeres_fn")))
-
-#define libc_freeres_fn(name)	\
-  static void name (void) __attribute_used__ __libc_freeres_fn_section;	\
-  text_set_element (__libc_subfreeres, name);				\
-  static void name (void)
 
 /* A canned warning for sysdeps/stub functions.  */
 #define	stub_warning(name) \
@@ -244,6 +234,79 @@ requires at runtime the shared libraries from the glibc version used \
 for linking")
 #endif
 
+/* Resource Freeing Hooks:
+
+   Normally a process exits and the OS cleans up any allocated
+   memory.  However, when tooling like mtrace or valgrind is monitoring
+   the process we need to free all resources that are part of the
+   process in order to provide the consistency required to track
+   memory leaks.
+
+   A single public API exists and is __libc_freeres(), and this is used
+   by applications like valgrind to freee resouces.
+
+   There are 3 cases:
+
+   (a) __libc_freeres
+
+	In this case all you need to do is define the freeing routine:
+
+	foo.c:
+	libfoo_freeres_fn (foo_freeres)
+	{
+	  complex_free (mem);
+	}
+
+	This ensures the function is called at the right point to free
+	resources.
+
+   (b) __libc_freeres_ptr
+
+	The framework for (a) iterates over the list of pointers-to-free
+	in (b) and frees them.
+
+	foo.c:
+	libc_freeres_ptr (static char *foo_buffer);
+
+	Freeing these resources alaways happens last and is equivalent
+	to registering a function that does 'free (foo_buffer)'.
+
+   (c) Explicit lists of free routines to call or objects to free.
+
+	It is the intended goal to remove (a) and (b) which have some
+	non-determinism based on link order, and instead use explicit
+	lists of functions and frees to resolve cleanup ordering issues
+	and make it easy to debug and maintain.
+
+	As of today the following subsystems use (c):
+
+	Per-thread cleanup:
+	* malloc/thread-freeres.c
+
+	libdl cleanup:
+	* dlfcn/dlfreeres.c
+
+	libpthread cleanup:
+	* nptl/nptlfreeres.c
+
+	So if you need any shutdown routines to run you should add them
+	directly to the appropriate subsystem's shutdown list.  */
+
+/* Resource pointers to free in libc.so.  */
+#define libc_freeres_ptr(decl) \
+  __make_section_unallocated ("__libc_freeres_ptrs, \"aw\", %nobits") \
+  decl __attribute__ ((section ("__libc_freeres_ptrs" __sec_comment)))
+
+/* Resource freeing functions from libc.so go in this section.  */
+#define __libc_freeres_fn_section \
+  __attribute__ ((section ("__libc_freeres_fn")))
+
+/* Resource freeing functions for libc.so.  */
+#define libc_freeres_fn(name) \
+  static void name (void) __attribute_used__ __libc_freeres_fn_section;	\
+  text_set_element (__libc_subfreeres, name);				\
+  static void name (void)
+
 /* Declare SYMBOL to be TYPE (`function' or `object') of SIZE bytes
    alias to ORIGINAL, when the assembler supports such declarations
    (such as in ELF).

include/set-hooks.h

@@ -22,11 +22,12 @@
 #define __need_size_t
 #include <stddef.h>
 #include <sys/cdefs.h>
+#include <libc-symbols.h>
 
 #ifdef symbol_set_define
 /* Define a hook variable called NAME.  Functions put on this hook take
    arguments described by PROTO.  Use `text_set_element (NAME, FUNCTION)'
-   from gnu-stabs.h to add a function to the hook.  */
+   from include/libc-symbols.h to add a function to the hook.  */
 
 # define DEFINE_HOOK(NAME, PROTO)		\
   typedef void __##NAME##_hook_function_t PROTO; \

malloc/set-freeres.c

@@ -26,6 +26,10 @@ DEFINE_HOOK (__libc_subfreeres, (void));
 
 symbol_set_define (__libc_freeres_ptrs);
 
+extern __attribute__ ((weak)) void __libdl_freeres (void);
+
+extern __attribute__ ((weak)) void __libpthread_freeres (void);
+
 void __libc_freeres_fn_section
 __libc_freeres (void)
 {
@@ -39,8 +43,19 @@ __libc_freeres (void)
 
       _IO_cleanup ();
 
+      /* We run the resource freeing after IO cleanup.  */
       RUN_HOOK (__libc_subfreeres, ());
 
+      /* Call the libdl list of cleanup functions
+	 (weak-ref-and-check).  */
+      if (&__libdl_freeres != NULL)
+	__libdl_freeres ();
+
+      /* Call the libpthread list of cleanup functions
+	 (weak-ref-and-check).  */
+      if (&__libpthread_freeres != NULL)
+	__libpthread_freeres ();
+
       for (p = symbol_set_first_element (__libc_freeres_ptrs);
            !symbol_set_end_p (__libc_freeres_ptrs, p); ++p)
         free (*p);

malloc/thread-freeres.c

@@ -24,8 +24,8 @@
 
 /* Thread shutdown function.  Note that this function must be called
    for threads during shutdown for correctness reasons.  Unlike
-   __libc_subfreeres, skipping calls to it is not a valid
+   __libc_subfreeres, skipping calls to it is not a valid optimization.
-   optimization.  */
+   This is called directly from pthread_create as the thread exits.  */
 void
 __libc_thread_freeres (void)
 {

nptl/Makefile

@@ -45,7 +45,7 @@ pthread-compat-wrappers = \
 		      sigwait sigsuspend \
 		      recvmsg sendmsg
 
-libpthread-routines = nptl-init vars events version pt-interp \
+libpthread-routines = nptl-init nptlfreeres vars events version pt-interp \
 		      pthread_create pthread_exit pthread_detach \
 		      pthread_join pthread_tryjoin pthread_timedjoin \
 		      pthread_join_common \

nptl/Versions

@@ -271,5 +271,6 @@ libpthread {
     __pthread_unwind; __pthread_get_minstack;
     __pthread_barrier_init; __pthread_barrier_wait;
     __shm_directory;
+    __libpthread_freeres;
   }
 }

nptl/allocatestack.c

@@ -251,8 +251,8 @@ get_cached_stack (size_t *sizep, void **memp)
 
 
 /* Free stacks until cache size is lower than LIMIT.  */
-void
+static void
-__free_stacks (size_t limit)
+free_stacks (size_t limit)
 {
   /* We reduce the size of the cache.  Remove the last entries until
      the size is below the limit.  */
@@ -288,6 +288,12 @@ __free_stacks (size_t limit)
     }
 }
 
+/* Free all the stacks on cleanup.  */
+void
+__nptl_stacks_freeres (void)
+{
+  free_stacks (0);
+}
 
 /* Add a stack frame which is not used anymore to the stack.  Must be
    called with the cache lock held.  */
@@ -302,7 +308,7 @@ queue_stack (struct pthread *stack)
 
   stack_cache_actsize += stack->stackblock_size;
   if (__glibc_unlikely (stack_cache_actsize > stack_cache_maxsize))
-    __free_stacks (stack_cache_maxsize);
+    free_stacks (stack_cache_maxsize);
 }
 
 

nptl/libc_pthread_init.c

@@ -77,11 +77,3 @@ __libc_pthread_init (unsigned long int *ptr, void (*reclaim) (void),
   return &__libc_multiple_threads;
 #endif
 }
-
-#ifdef SHARED
-libc_freeres_fn (freeres_libptread)
-{
-  if (__libc_pthread_functions_init)
-    PTHFCT_CALL (ptr_freeres, ());
-}
-#endif

nptl/nptl-init.c

@@ -78,9 +78,6 @@ extern
 void __nptl_set_robust (struct pthread *);
 
 #ifdef SHARED
-static void nptl_freeres (void);
-
-
 static const struct pthread_functions pthread_functions =
   {
     .ptr_pthread_attr_destroy = __pthread_attr_destroy,
@@ -140,8 +137,6 @@ static const struct pthread_functions pthread_functions =
 # ifdef SIGSETXID
     .ptr__nptl_setxid = __nptl_setxid,
 # endif
-    /* For now only the stack cache needs to be freed.  */
-    .ptr_freeres = nptl_freeres,
     .ptr_set_robust = __nptl_set_robust
   };
 # define ptr_pthread_functions &pthread_functions
@@ -151,16 +146,6 @@ static const struct pthread_functions pthread_functions =
 
 
 #ifdef SHARED
-/* This function is called indirectly from the freeres code in libc.  */
-static void
-__libc_freeres_fn_section
-nptl_freeres (void)
-{
-  __unwind_freeres ();
-  __free_stacks (0);
-}
-
-
 static
 #endif
 void

nptl/nptlfreeres.c

@@ -0,0 +1,31 @@
+/* Clean up allocated libpthread memory on demand.
+   Copyright (C) 2018 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <set-hooks.h>
+#include <libc-symbols.h>
+#include <pthreadP.h>
+
+/* Free libpthread.so resources.
+   Note: Caller ensures we are called only once.  */
+void
+__libpthread_freeres (void)
+{
+  call_function_static_weak (__nptl_stacks_freeres);
+  call_function_static_weak (__shm_directory_freeres);
+  call_function_static_weak (__nptl_unwind_freeres);
+}

nptl/pthreadP.h

@@ -279,8 +279,8 @@ hidden_proto (__pthread_register_cancel)
 hidden_proto (__pthread_unregister_cancel)
 # ifdef SHARED
 extern void attribute_hidden pthread_cancel_init (void);
-extern void __unwind_freeres (void);
 # endif
+extern void __nptl_unwind_freeres (void) attribute_hidden;
 #endif
 
 
@@ -597,7 +597,8 @@ extern int __nptl_setxid (struct xid_command *cmdp) attribute_hidden;
 extern void __nptl_set_robust (struct pthread *self);
 #endif
 
-extern void __free_stacks (size_t limit) attribute_hidden;
+extern void __nptl_stacks_freeres (void) attribute_hidden;
+extern void __shm_directory_freeres (void) attribute_hidden;
 
 extern void __wait_lookup_done (void) attribute_hidden;
 

resolv/res-close.c

@@ -140,4 +140,5 @@ __res_thread_freeres (void)
   /* Make sure we do a full re-initialization the next time.  */
   _res.options = 0;
 }
+/* Also must be called when the main thread exits.  */
 text_set_element (__libc_subfreeres, __res_thread_freeres);

resolv/resolv_conf.c

@@ -23,6 +23,7 @@
 #include <libc-lock.h>
 #include <resolv-internal.h>
 #include <sys/stat.h>
+#include <libc-symbols.h>
 
 /* _res._u._ext.__glibc_extension_index is used as an index into a
    struct resolv_conf_array object.  The intent of this construction

string/strerror_l.c

@@ -21,7 +21,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <sys/param.h>
-
+#include <libc-symbols.h>
 
 static __thread char *last_value;
 
@@ -56,7 +56,6 @@ strerror_l (int errnum, locale_t loc)
   return (char *) translate (_sys_errlist_internal[errnum], loc);
 }
 
-
 void
 __strerror_thread_freeres (void)
 {

sunrpc/rpc_thread.c

@@ -5,6 +5,7 @@
 #include <libc-lock.h>
 #include <libc-tsd.h>
 #include <shlib-compat.h>
+#include <libc-symbols.h>
 
 
 /* Variable used in non-threaded applications or for the first thread.  */

sysdeps/mach/strerror_l.c

@@ -24,6 +24,7 @@
 #include <mach/error.h>
 #include <errorlib.h>
 #include <sys/param.h>
+#include <libc-symbols.h>
 
 
 static __thread char *last_value;
@@ -86,7 +87,7 @@ strerror_l (int errnum, locale_t loc)
   return (char *) translate (es->subsystem[sub].codes[code], loc);
 }
 
-
+/* This is called when a thread is exiting to free the last_value string.  */
 void
 __strerror_thread_freeres (void)
 {

sysdeps/nptl/pthread-functions.h

@@ -94,7 +94,6 @@ struct pthread_functions
        __attribute ((noreturn)) __cleanup_fct_attribute;
   void (*ptr__nptl_deallocate_tsd) (void);
   int (*ptr__nptl_setxid) (struct xid_command *);
-  void (*ptr_freeres) (void);
   void (*ptr_set_robust) (struct pthread *);
 };
 

sysdeps/nptl/unwind-forcedunwind.c

@@ -79,9 +79,9 @@ pthread_cancel_init (void)
   libgcc_s_handle = handle;
 }
 
+/* Register for cleanup in libpthread.so.  */
 void
-__libc_freeres_fn_section
+__nptl_unwind_freeres (void)
-__unwind_freeres (void)
 {
   void *handle = libgcc_s_handle;
   if (handle != NULL)

sysdeps/unix/sysv/linux/shm-directory.c

@@ -135,13 +135,13 @@ __shm_directory (size_t *len)
 }
 #if IS_IN (libpthread)
 hidden_def (__shm_directory)
-#endif
-
 
 /* Make sure the table is freed if we want to free everything before
    exiting.  */
-libc_freeres_fn (freeit)
+void
+__shm_directory_freeres (void)
 {
   if (mountpoint.dir != defaultdir)
     free (mountpoint.dir);
 }
+#endif