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-rw-r--r--malloc/Makefile47
-rw-r--r--malloc/Versions20
-rw-r--r--malloc/arena.c7
-rw-r--r--malloc/hooks.c64
-rw-r--r--malloc/malloc-debug.c189
-rw-r--r--malloc/malloc.c85
-rw-r--r--malloc/mcheck.c1
-rw-r--r--malloc/mtrace.c1
-rw-r--r--malloc/tst-compathooks-off.c145
-rw-r--r--malloc/tst-compathooks-on.c2
-rw-r--r--malloc/tst-malloc-usable-static-tunables.c1
-rw-r--r--malloc/tst-malloc-usable-static.c1
-rwxr-xr-xmalloc/tst-mtrace.sh1
13 files changed, 453 insertions, 111 deletions
diff --git a/malloc/Makefile b/malloc/Makefile
index bbb70f6f87..cafe427097 100644
--- a/malloc/Makefile
+++ b/malloc/Makefile
@@ -46,12 +46,11 @@ tests := mallocbug tst-malloc tst-valloc tst-calloc tst-obstack \
 
 tests-static := \
 	 tst-interpose-static-nothread \
-	 tst-interpose-static-thread \
-	 tst-malloc-usable-static \
+	 tst-interpose-static-thread
 
 # Test for the malloc_set_state symbol removed in glibc 2.25.
-ifeq ($(have-GLIBC_2.24)$(build-shared),yesyes)
-tests += tst-mallocstate
+ifeq ($(have-GLIBC_2.23)$(build-shared),yesyes)
+tests += tst-mallocstate tst-compathooks-off tst-compathooks-on
 endif
 
 tests-internal := tst-scratch_buffer
@@ -64,7 +63,6 @@ tests-internal += \
 
 ifneq (no,$(have-tunables))
 tests += tst-malloc-usable-tunables tst-mxfast
-tests-static += tst-malloc-usable-static-tunables
 endif
 
 tests += $(tests-static)
@@ -73,7 +71,8 @@ test-srcs = tst-mtrace
 # These tests either are run with MALLOC_CHECK_=3 by default or do not work
 # with MALLOC_CHECK_=3 because they expect a specific failure.
 tests-exclude-malloc-check = tst-malloc-check tst-malloc-usable \
-	tst-mxfast tst-safe-linking
+	tst-mxfast tst-safe-linking \
+	tst-compathooks-off tst-compathooks-on
 
 # Run all tests with MALLOC_CHECK_=3
 tests-malloc-check = $(filter-out $(tests-exclude-malloc-check),$(tests))
@@ -91,15 +90,14 @@ tests-exclude-mcheck = tst-mallocstate \
 	tst-malloc-tcache-leak \
 	tst-malloc-thread-exit \
 	tst-malloc-thread-fail \
-	tst-malloc-usable-static \
-	tst-malloc-usable-static-tunables \
 	tst-malloc-usable-tunables \
 	tst-malloc_info \
 	tst-memalign \
 	tst-posix_memalign \
 	tst-realloc \
 	tst-pvalloc-fortify \
-	tst-reallocarray
+	tst-reallocarray \
+	tst-compathooks-off tst-compathooks-on
 
 tests-mcheck = $(filter-out $(tests-exclude-mcheck), $(tests))
 endif
@@ -122,8 +120,8 @@ routines = malloc mcheck mtrace obstack reallocarray \
 install-lib := libmcheck.a
 non-lib.a := libmcheck.a
 
-# Additional library.
-extra-libs = libmemusage
+# Additional libraries.
+extra-libs = libmemusage libc_malloc_debug
 extra-libs-others = $(extra-libs)
 
 # Helper objects for some tests.
@@ -138,6 +136,9 @@ test-extras = \
 libmemusage-routines = memusage
 libmemusage-inhibit-o = $(filter-out .os,$(object-suffixes))
 
+libc_malloc_debug-routines = malloc-debug
+libc_malloc_debug-inhibit-o = $(filter-out .os,$(object-suffixes))
+
 $(objpfx)tst-malloc-backtrace: $(shared-thread-library)
 $(objpfx)tst-malloc-thread-exit: $(shared-thread-library)
 $(objpfx)tst-malloc-thread-fail: $(shared-thread-library)
@@ -244,11 +245,12 @@ endif
 endif
 endif
 
-tst-malloc-check-ENV = MALLOC_CHECK_=3
-tst-malloc-usable-ENV = MALLOC_CHECK_=3
-tst-malloc-usable-static-ENV = $(tst-malloc-usable-ENV)
-tst-malloc-usable-tunables-ENV = GLIBC_TUNABLES=glibc.malloc.check=3
-tst-malloc-usable-static-tunables-ENV = $(tst-malloc-usable-tunables-ENV)
+tst-malloc-check-ENV = MALLOC_CHECK_=3 \
+		       LD_PRELOAD=$(objpfx)/libc_malloc_debug.so
+tst-malloc-usable-ENV = MALLOC_CHECK_=3 \
+		       LD_PRELOAD=$(objpfx)/libc_malloc_debug.so
+tst-malloc-usable-tunables-ENV = GLIBC_TUNABLES=glibc.malloc.check=3 \
+				 LD_PRELOAD=$(objpfx)/libc_malloc_debug.so
 
 tst-mxfast-ENV = GLIBC_TUNABLES=glibc.malloc.tcache_count=0:glibc.malloc.mxfast=0
 
@@ -303,12 +305,14 @@ $(objpfx)tst-interpose-static-thread-mcheck: \
 $(objpfx)tst-interpose-static-thread-malloc-check: \
   $(objpfx)tst-interpose-aux-thread.o $(static-thread-library)
 
-tst-dynarray-ENV = MALLOC_TRACE=$(objpfx)tst-dynarray.mtrace
+tst-dynarray-ENV = MALLOC_TRACE=$(objpfx)tst-dynarray.mtrace \
+		   LD_PRELOAD=$(objpfx)libc_malloc_debug.so
 $(objpfx)tst-dynarray-mem.out: $(objpfx)tst-dynarray.out
 	$(common-objpfx)malloc/mtrace $(objpfx)tst-dynarray.mtrace > $@; \
 	$(evaluate-test)
 
-tst-dynarray-fail-ENV = MALLOC_TRACE=$(objpfx)tst-dynarray-fail.mtrace
+tst-dynarray-fail-ENV = MALLOC_TRACE=$(objpfx)tst-dynarray-fail.mtrace \
+			LD_PRELOAD=$(objpfx)libc_malloc_debug.so
 $(objpfx)tst-dynarray-fail-mem.out: $(objpfx)tst-dynarray-fail.out
 	$(common-objpfx)malloc/mtrace $(objpfx)tst-dynarray-fail.mtrace > $@; \
 	$(evaluate-test)
@@ -322,3 +326,10 @@ $(objpfx)tst-mallocfork2-mcheck: $(shared-thread-library)
 $(objpfx)tst-malloc-tcache-leak-malloc-check: $(shared-thread-library)
 $(objpfx)tst-malloc_info-malloc-check: $(shared-thread-library)
 $(objpfx)tst-mallocfork2-malloc-check: $(shared-thread-library)
+
+tst-compathooks-on-ENV = LD_PRELOAD=$(objpfx)libc_malloc_debug.so
+tst-compathooks-on-mcheck-ENV = LD_PRELOAD=$(objpfx)libc_malloc_debug.so
+tst-compathooks-on-malloc-check-ENV = \
+	LD_PRELOAD=$(objpfx)libc_malloc_debug.so
+tst-mallocstate-ENV = LD_PRELOAD=$(objpfx)libc_malloc_debug.so
+tst-mallocstate-malloc-check-ENV = LD_PRELOAD=$(objpfx)libc_malloc_debug.so
diff --git a/malloc/Versions b/malloc/Versions
index 470a940666..c87f6df8ca 100644
--- a/malloc/Versions
+++ b/malloc/Versions
@@ -98,3 +98,23 @@ libc {
     __libc_alloc_buffer_create_failure;
   }
 }
+
+# Keep in sync with symbols in libc.
+libc_malloc_debug {
+  GLIBC_2.0 {
+    calloc;
+    free;
+    malloc;
+    memalign;
+    pvalloc;
+    realloc;
+    valloc;
+
+  }
+  GLIBC_2.2 {
+    posix_memalign;
+  }
+  GLIBC_2.16 {
+    aligned_alloc;
+  }
+}
diff --git a/malloc/arena.c b/malloc/arena.c
index f1693ed48f..9111b49589 100644
--- a/malloc/arena.c
+++ b/malloc/arena.c
@@ -404,13 +404,6 @@ ptmalloc_init (void)
   if (s && s[0] != '\0' && s[0] != '0')
     __malloc_check_init ();
 #endif
-
-#if HAVE_MALLOC_INIT_HOOK
-  void (*hook) (void) = atomic_forced_read (__malloc_initialize_hook);
-  if (hook != NULL)
-    (*hook)();
-#endif
-  __malloc_initialized = 1;
 }
 
 /* Managing heaps and arenas (for concurrent threads) */
diff --git a/malloc/hooks.c b/malloc/hooks.c
index 4aa6dadcff..3cd44eeb84 100644
--- a/malloc/hooks.c
+++ b/malloc/hooks.c
@@ -1,4 +1,4 @@
-/* Malloc implementation for multiple threads without lock contention.
+/* Compatibility code for malloc debugging and state management.
    Copyright (C) 2001-2021 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
    Contributed by Wolfram Gloger <wg@malloc.de>, 2001.
@@ -17,6 +17,16 @@
    License along with the GNU C Library; see the file COPYING.LIB.  If
    not, see <https://www.gnu.org/licenses/>.  */
 
+#ifndef weak_variable
+# define weak_variable weak_function
+#endif
+
+#if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_24)
+void (*__malloc_initialize_hook) (void);
+compat_symbol (libc, __malloc_initialize_hook,
+	       __malloc_initialize_hook, GLIBC_2_0);
+#endif
+
 #if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_34)
 void weak_variable (*__after_morecore_hook) (void) = NULL;
 compat_symbol (libc, __after_morecore_hook, __after_morecore_hook, GLIBC_2_0);
@@ -24,32 +34,64 @@ void *(*__morecore)(ptrdiff_t);
 compat_symbol (libc, __morecore, __morecore, GLIBC_2_0);
 #endif
 
+static void *malloc_hook_ini (size_t, const void *) __THROW;
+static void *realloc_hook_ini (void *, size_t, const void *) __THROW;
+static void *memalign_hook_ini (size_t, size_t, const void *) __THROW;
+
+void weak_variable (*__free_hook) (void *, const void *) = NULL;
+void *weak_variable (*__malloc_hook)
+  (size_t, const void *) = malloc_hook_ini;
+void *weak_variable (*__realloc_hook)
+  (void *, size_t, const void *) = realloc_hook_ini;
+void *weak_variable (*__memalign_hook)
+  (size_t, size_t, const void *) = memalign_hook_ini;
+
 /* Hooks for debugging versions.  The initial hooks just call the
    initialization routine, then do the normal work. */
 
-static void *
-malloc_hook_ini (size_t sz, const void *caller)
+/* These hooks will get executed only through the interposed allocator
+   functions in libc_malloc_debug.so.  This means that the calls to malloc,
+   realloc, etc. will lead back into the interposed functions, which is what we
+   want.
+
+   These initial hooks are assumed to be called in a single-threaded context,
+   so it is safe to reset all hooks at once upon initialization.  */
+
+static void
+generic_hook_ini (void)
 {
   __malloc_hook = NULL;
+  __realloc_hook = NULL;
+  __memalign_hook = NULL;
   ptmalloc_init ();
-  return __libc_malloc (sz);
+
+#if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_24)
+  void (*hook) (void) = atomic_forced_read (__malloc_initialize_hook);
+  if (hook != NULL)
+    (*hook)();
+#endif
+  __malloc_initialized = 1;
+}
+
+static void *
+malloc_hook_ini (size_t sz, const void *caller)
+{
+  generic_hook_ini ();
+  return malloc (sz);
 }
 
 static void *
 realloc_hook_ini (void *ptr, size_t sz, const void *caller)
 {
-  __malloc_hook = NULL;
-  __realloc_hook = NULL;
-  ptmalloc_init ();
-  return __libc_realloc (ptr, sz);
+  generic_hook_ini ();
+  return realloc (ptr, sz);
 }
 
 static void *
 memalign_hook_ini (size_t alignment, size_t sz, const void *caller)
 {
-  __memalign_hook = NULL;
-  ptmalloc_init ();
-  return __libc_memalign (alignment, sz);
+  generic_hook_ini ();
+  return memalign (alignment, sz);
 }
 
 #include "malloc-check.c"
diff --git a/malloc/malloc-debug.c b/malloc/malloc-debug.c
new file mode 100644
index 0000000000..41dfcd3369
--- /dev/null
+++ b/malloc/malloc-debug.c
@@ -0,0 +1,189 @@
+/* Malloc debug DSO.
+   Copyright (C) 2021 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; see the file COPYING.LIB.  If
+   not, see <https://www.gnu.org/licenses/>.  */
+
+#include <atomic.h>
+#include <libc-symbols.h>
+#include <shlib-compat.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/param.h>
+
+/* Support only the glibc allocators.  */
+extern void *__libc_malloc (size_t);
+extern void __libc_free (void *);
+extern void *__libc_realloc (void *, size_t);
+extern void *__libc_memalign (size_t, size_t);
+extern void *__libc_valloc (size_t);
+extern void *__libc_pvalloc (size_t);
+extern void *__libc_calloc (size_t, size_t);
+
+#define DEBUG_FN(fn) \
+  static __typeof (__libc_ ## fn) __debug_ ## fn
+
+DEBUG_FN(malloc);
+DEBUG_FN(free);
+DEBUG_FN(realloc);
+DEBUG_FN(memalign);
+DEBUG_FN(valloc);
+DEBUG_FN(pvalloc);
+DEBUG_FN(calloc);
+
+extern void (*__free_hook) (void *, const void *);
+compat_symbol_reference (libc, __free_hook, __free_hook, GLIBC_2_0);
+extern void * (*__malloc_hook) (size_t, const void *);
+compat_symbol_reference (libc, __malloc_hook, __malloc_hook, GLIBC_2_0);
+extern void * (*__realloc_hook) (void *, size_t, const void *);
+compat_symbol_reference (libc, __realloc_hook, __realloc_hook, GLIBC_2_0);
+extern void * (*__memalign_hook) (size_t, size_t, const void *);
+compat_symbol_reference (libc, __memalign_hook, __memalign_hook, GLIBC_2_0);
+
+static size_t pagesize;
+
+/* The allocator functions.  */
+
+static void *
+__debug_malloc (size_t bytes)
+{
+  void *(*hook) (size_t, const void *) = atomic_forced_read (__malloc_hook);
+  if (__builtin_expect (hook != NULL, 0))
+    return (*hook)(bytes, RETURN_ADDRESS (0));
+
+  return __libc_malloc (bytes);
+}
+strong_alias (__debug_malloc, malloc)
+
+static void
+__debug_free (void *mem)
+{
+  void (*hook) (void *, const void *) = atomic_forced_read (__free_hook);
+  if (__builtin_expect (hook != NULL, 0))
+    {
+      (*hook)(mem, RETURN_ADDRESS (0));
+      return;
+    }
+  __libc_free (mem);
+}
+strong_alias (__debug_free, free)
+
+static void *
+__debug_realloc (void *oldmem, size_t bytes)
+{
+  void *(*hook) (void *, size_t, const void *) =
+    atomic_forced_read (__realloc_hook);
+  if (__builtin_expect (hook != NULL, 0))
+    return (*hook)(oldmem, bytes, RETURN_ADDRESS (0));
+
+  return __libc_realloc (oldmem, bytes);
+}
+strong_alias (__debug_realloc, realloc)
+
+static void *
+_debug_mid_memalign (size_t alignment, size_t bytes, const void *address)
+{
+  void *(*hook) (size_t, size_t, const void *) =
+    atomic_forced_read (__memalign_hook);
+  if (__builtin_expect (hook != NULL, 0))
+    return (*hook)(alignment, bytes, address);
+
+  return __libc_memalign (alignment, bytes);
+}
+
+static void *
+__debug_memalign (size_t alignment, size_t bytes)
+{
+  return _debug_mid_memalign (alignment, bytes, RETURN_ADDRESS (0));
+}
+strong_alias (__debug_memalign, memalign)
+strong_alias (__debug_memalign, aligned_alloc)
+
+static void *
+__debug_pvalloc (size_t bytes)
+{
+  size_t rounded_bytes;
+
+  if (!pagesize)
+    pagesize = sysconf (_SC_PAGESIZE);
+
+  /* ALIGN_UP with overflow check.  */
+  if (__glibc_unlikely (__builtin_add_overflow (bytes,
+						pagesize - 1,
+						&rounded_bytes)))
+    {
+      errno = ENOMEM;
+      return NULL;
+    }
+  rounded_bytes = rounded_bytes & -(pagesize - 1);
+
+  return _debug_mid_memalign (pagesize, rounded_bytes, RETURN_ADDRESS (0));
+}
+strong_alias (__debug_pvalloc, pvalloc)
+
+static void *
+__debug_valloc (size_t bytes)
+{
+  if (!pagesize)
+    pagesize = sysconf (_SC_PAGESIZE);
+
+  return _debug_mid_memalign (pagesize, bytes, RETURN_ADDRESS (0));
+}
+strong_alias (__debug_valloc, valloc)
+
+static int
+__debug_posix_memalign (void **memptr, size_t alignment, size_t bytes)
+{
+  /* Test whether the SIZE argument is valid.  It must be a power of
+     two multiple of sizeof (void *).  */
+  if (alignment % sizeof (void *) != 0
+      || !powerof2 (alignment / sizeof (void *))
+      || alignment == 0)
+    return EINVAL;
+
+  *memptr = _debug_mid_memalign (alignment, bytes, RETURN_ADDRESS (0));
+
+  if (*memptr == NULL)
+    return ENOMEM;
+
+  return 0;
+}
+strong_alias (__debug_posix_memalign, posix_memalign)
+
+static void *
+__debug_calloc (size_t nmemb, size_t size)
+{
+  void *(*hook) (size_t, const void *) = atomic_forced_read (__malloc_hook);
+  if (__builtin_expect (hook != NULL, 0))
+    {
+      size_t bytes;
+
+      if (__glibc_unlikely (__builtin_mul_overflow (nmemb, size, &bytes)))
+	{
+	  errno = ENOMEM;
+	  return NULL;
+	}
+
+      void *mem = (*hook)(bytes, RETURN_ADDRESS (0));
+
+      if (mem != NULL)
+	memset (mem, 0, bytes);
+
+      return mem;
+    }
+
+  return __libc_calloc (nmemb, size);
+}
+strong_alias (__debug_calloc, calloc)
diff --git a/malloc/malloc.c b/malloc/malloc.c
index 6e8fa9e424..cf71314b2b 100644
--- a/malloc/malloc.c
+++ b/malloc/malloc.c
@@ -573,16 +573,6 @@ tag_at (void *ptr)
 #define HAVE_MREMAP 0
 #endif
 
-/* We may need to support __malloc_initialize_hook for backwards
-   compatibility.  */
-
-#if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_24)
-# define HAVE_MALLOC_INIT_HOOK 1
-#else
-# define HAVE_MALLOC_INIT_HOOK 0
-#endif
-
-
 /*
   This version of malloc supports the standard SVID/XPG mallinfo
   routine that returns a struct containing usage properties and
@@ -2008,38 +1998,6 @@ static void     malloc_consolidate (mstate);
 
 /* -------------- Early definitions for debugging hooks ---------------- */
 
-/* Define and initialize the hook variables.  These weak definitions must
-   appear before any use of the variables in a function (arena.c uses one).  */
-#ifndef weak_variable
-/* In GNU libc we want the hook variables to be weak definitions to
-   avoid a problem with Emacs.  */
-# define weak_variable weak_function
-#endif
-
-/* Forward declarations.  */
-static void *malloc_hook_ini (size_t sz,
-                              const void *caller) __THROW;
-static void *realloc_hook_ini (void *ptr, size_t sz,
-                               const void *caller) __THROW;
-static void *memalign_hook_ini (size_t alignment, size_t sz,
-                                const void *caller) __THROW;
-
-#if HAVE_MALLOC_INIT_HOOK
-void (*__malloc_initialize_hook) (void);
-compat_symbol (libc, __malloc_initialize_hook,
-	       __malloc_initialize_hook, GLIBC_2_0);
-#endif
-
-void weak_variable (*__free_hook) (void *__ptr,
-                                   const void *) = NULL;
-void *weak_variable (*__malloc_hook)
-  (size_t __size, const void *) = malloc_hook_ini;
-void *weak_variable (*__realloc_hook)
-  (void *__ptr, size_t __size, const void *)
-  = realloc_hook_ini;
-void *weak_variable (*__memalign_hook)
-  (size_t __alignment, size_t __size, const void *)
-  = memalign_hook_ini;
 /* This function is called from the arena shutdown hook, to free the
    thread cache (if it exists).  */
 static void tcache_thread_shutdown (void);
@@ -3237,10 +3195,8 @@ __libc_malloc (size_t bytes)
   _Static_assert (PTRDIFF_MAX <= SIZE_MAX / 2,
                   "PTRDIFF_MAX is not more than half of SIZE_MAX");
 
-  void *(*hook) (size_t, const void *)
-    = atomic_forced_read (__malloc_hook);
-  if (__builtin_expect (hook != NULL, 0))
-    return (*hook)(bytes, RETURN_ADDRESS (0));
+  if (__malloc_initialized < 0)
+    ptmalloc_init ();
 #if USE_TCACHE
   /* int_free also calls request2size, be careful to not pad twice.  */
   size_t tbytes;
@@ -3301,14 +3257,6 @@ __libc_free (void *mem)
   mstate ar_ptr;
   mchunkptr p;                          /* chunk corresponding to mem */
 
-  void (*hook) (void *, const void *)
-    = atomic_forced_read (__free_hook);
-  if (__builtin_expect (hook != NULL, 0))
-    {
-      (*hook)(mem, RETURN_ADDRESS (0));
-      return;
-    }
-
   if (mem == 0)                              /* free(0) has no effect */
     return;
 
@@ -3360,10 +3308,8 @@ __libc_realloc (void *oldmem, size_t bytes)
 
   void *newp;             /* chunk to return */
 
-  void *(*hook) (void *, size_t, const void *) =
-    atomic_forced_read (__realloc_hook);
-  if (__builtin_expect (hook != NULL, 0))
-    return (*hook)(oldmem, bytes, RETURN_ADDRESS (0));
+  if (__malloc_initialized < 0)
+    ptmalloc_init ();
 
 #if REALLOC_ZERO_BYTES_FREES
   if (bytes == 0 && oldmem != NULL)
@@ -3498,6 +3444,9 @@ libc_hidden_def (__libc_realloc)
 void *
 __libc_memalign (size_t alignment, size_t bytes)
 {
+  if (__malloc_initialized < 0)
+    ptmalloc_init ();
+
   void *address = RETURN_ADDRESS (0);
   return _mid_memalign (alignment, bytes, address);
 }
@@ -3508,11 +3457,6 @@ _mid_memalign (size_t alignment, size_t bytes, void *address)
   mstate ar_ptr;
   void *p;
 
-  void *(*hook) (size_t, size_t, const void *) =
-    atomic_forced_read (__memalign_hook);
-  if (__builtin_expect (hook != NULL, 0))
-    return (*hook)(alignment, bytes, address);
-
   /* If we need less alignment than we give anyway, just relay to malloc.  */
   if (alignment <= MALLOC_ALIGNMENT)
     return __libc_malloc (bytes);
@@ -3621,16 +3565,8 @@ __libc_calloc (size_t n, size_t elem_size)
 
   sz = bytes;
 
-  void *(*hook) (size_t, const void *) =
-    atomic_forced_read (__malloc_hook);
-  if (__builtin_expect (hook != NULL, 0))
-    {
-      mem = (*hook)(sz, RETURN_ADDRESS (0));
-      if (mem == 0)
-        return 0;
-
-      return memset (mem, 0, sz);
-    }
+  if (__malloc_initialized < 0)
+    ptmalloc_init ();
 
   MAYBE_INIT_TCACHE ();
 
@@ -5659,6 +5595,9 @@ __posix_memalign (void **memptr, size_t alignment, size_t size)
 {
   void *mem;
 
+  if (__malloc_initialized < 0)
+    ptmalloc_init ();
+
   /* Test whether the SIZE argument is valid.  It must be a power of
      two multiple of sizeof (void *).  */
   if (alignment % sizeof (void *) != 0
diff --git a/malloc/mcheck.c b/malloc/mcheck.c
index d2efcfb742..1e68cedbf5 100644
--- a/malloc/mcheck.c
+++ b/malloc/mcheck.c
@@ -26,6 +26,7 @@
 # include <stdio.h>
 # include <libintl.h>
 # include <errno.h>
+# include <malloc-internal.h>
 #endif
 
 /* Old hook values.  */
diff --git a/malloc/mtrace.c b/malloc/mtrace.c
index 6c2c58b706..fb58413d39 100644
--- a/malloc/mtrace.c
+++ b/malloc/mtrace.c
@@ -22,6 +22,7 @@
 # define _MALLOC_INTERNAL
 # include <malloc.h>
 # include <mcheck.h>
+# include <malloc-internal.h>
 # include <libc-lock.h>
 #endif
 
diff --git a/malloc/tst-compathooks-off.c b/malloc/tst-compathooks-off.c
new file mode 100644
index 0000000000..7b3722d8b3
--- /dev/null
+++ b/malloc/tst-compathooks-off.c
@@ -0,0 +1,145 @@
+/* Minimal tests to verify libc_malloc_debug.so functionality.
+   Copyright (C) 2021 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
+   <https://www.gnu.org/licenses/>.  */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <malloc.h>
+#include <shlib-compat.h>
+#include <libc-diag.h>
+
+#include <support/check.h>
+#include <support/support.h>
+
+extern void (*volatile __free_hook) (void *, const void *);
+extern void *(*volatile __malloc_hook)(size_t, const void *);
+extern void *(*volatile __realloc_hook)(void *, size_t, const void *);
+extern void *(*volatile __memalign_hook)(size_t, size_t, const void *);
+
+int hook_count, call_count;
+
+DIAG_PUSH_NEEDS_COMMENT;
+DIAG_IGNORE_NEEDS_COMMENT (4.9, "-Wdeprecated-declarations");
+
+void
+free_called (void *mem, const void *address)
+{
+  hook_count++;
+  __free_hook = NULL;
+  free (mem);
+  __free_hook = free_called;
+}
+
+void *
+malloc_called (size_t bytes, const void *address)
+{
+  hook_count++;
+  __malloc_hook = NULL;
+  void *mem = malloc (bytes);
+  __malloc_hook = malloc_called;
+  return mem;
+}
+
+void *
+realloc_called (void *oldptr, size_t bytes, const void *address)
+{
+  hook_count++;
+  __realloc_hook = NULL;
+  void *mem = realloc (oldptr, bytes);
+  __realloc_hook = realloc_called;
+  return mem;
+}
+
+void *
+calloc_called (size_t n, size_t size, const void *address)
+{
+  hook_count++;
+  __malloc_hook = NULL;
+  void *mem = calloc (n, size);
+  __malloc_hook = malloc_called;
+  return mem;
+}
+
+void *
+memalign_called (size_t align, size_t size, const void *address)
+{
+  hook_count++;
+  __memalign_hook = NULL;
+  void *mem = memalign (align, size);
+  __memalign_hook = memalign_called;
+  return mem;
+}
+
+static void initialize_hooks (void)
+{
+  __free_hook = free_called;
+  __malloc_hook = malloc_called;
+  __realloc_hook = realloc_called;
+  __memalign_hook = memalign_called;
+}
+void (*__malloc_initialize_hook) (void) = initialize_hooks;
+compat_symbol_reference (libc, __malloc_initialize_hook,
+			 __malloc_initialize_hook, GLIBC_2_0);
+compat_symbol_reference (libc, __free_hook,
+			 __free_hook, GLIBC_2_0);
+compat_symbol_reference (libc, __malloc_hook,
+			 __malloc_hook, GLIBC_2_0);
+compat_symbol_reference (libc, __realloc_hook,
+			 __realloc_hook, GLIBC_2_0);
+compat_symbol_reference (libc, __memalign_hook,
+			 __memalign_hook, GLIBC_2_0);
+
+DIAG_POP_NEEDS_COMMENT;
+
+static int
+do_test (void)
+{
+  void *p;
+  p = malloc (0);
+  TEST_VERIFY_EXIT (p != NULL);
+  call_count++;
+
+  p = realloc (p, 0);
+  TEST_VERIFY_EXIT (p == NULL);
+  call_count++;
+
+  p = calloc (512, 1);
+  TEST_VERIFY_EXIT (p != NULL);
+  call_count++;
+
+  free (p);
+  call_count++;
+
+  p = memalign (0x100, 0x100);
+  TEST_VERIFY_EXIT (p != NULL);
+  call_count++;
+
+  free (p);
+  call_count++;
+
+  printf ("call_count: %d, hook_count: %d\n", call_count, hook_count);
+
+#ifdef HOOKS_ENABLED
+  TEST_VERIFY_EXIT (call_count == hook_count);
+#else
+  TEST_VERIFY_EXIT (hook_count == 0);
+#endif
+
+  exit (0);
+}
+
+#include <support/test-driver.c>
diff --git a/malloc/tst-compathooks-on.c b/malloc/tst-compathooks-on.c
new file mode 100644
index 0000000000..4da183687a
--- /dev/null
+++ b/malloc/tst-compathooks-on.c
@@ -0,0 +1,2 @@
+#define HOOKS_ENABLED 1
+#include "tst-compathooks-off.c"
diff --git a/malloc/tst-malloc-usable-static-tunables.c b/malloc/tst-malloc-usable-static-tunables.c
deleted file mode 100644
index 8907db01a5..0000000000
--- a/malloc/tst-malloc-usable-static-tunables.c
+++ /dev/null
@@ -1 +0,0 @@
-#include <malloc/tst-malloc-usable.c>
diff --git a/malloc/tst-malloc-usable-static.c b/malloc/tst-malloc-usable-static.c
deleted file mode 100644
index 8907db01a5..0000000000
--- a/malloc/tst-malloc-usable-static.c
+++ /dev/null
@@ -1 +0,0 @@
-#include <malloc/tst-malloc-usable.c>
diff --git a/malloc/tst-mtrace.sh b/malloc/tst-mtrace.sh
index 9295683aff..a830204d5e 100755
--- a/malloc/tst-mtrace.sh
+++ b/malloc/tst-mtrace.sh
@@ -30,6 +30,7 @@ trap "rm -f ${common_objpfx}malloc/tst-mtrace.leak; exit 1" 1 2 15
 ${test_program_prefix_before_env} \
 ${run_program_env} \
 MALLOC_TRACE=${common_objpfx}malloc/tst-mtrace.leak \
+LD_PRELOAD=${common_objpfx}malloc/libc_malloc_debug.so \
 ${test_program_prefix_after_env} \
   ${common_objpfx}malloc/tst-mtrace || status=1