[PATCH v2] Add a generic malloc test for MALLOC_ALIGNMENT

["H.J. Lu via Libc-alpha" <libc-alpha@sourceware.org>]

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On Thu, Jul 8, 2021 at 9:07 PM Siddhesh Poyarekar <siddhesh@gotplt.org> wrote:
>
> > diff --git a/malloc/Makefile b/malloc/Makefile
> > index 37a9a4efab..b685ed6d61 100644
> > --- a/malloc/Makefile
> > +++ b/malloc/Makefile
> > @@ -42,6 +42,7 @@ tests := mallocbug tst-malloc tst-valloc tst-calloc tst-obstack \
> >        tst-malloc-stats-cancellation \
> >        tst-tcfree1 tst-tcfree2 tst-tcfree3 \
> >        tst-safe-linking \
> > +      tst-mallocalign1 \
> >
>
> Please remove the trailing '\'.  OK otherwise.
>

Changes in the v2 patch

1. Add a comment in malloc/tst-mallocalign1.c to indicate that it is
used to verify that MALLOC_ALIGNMENT is honored by malloc.
2. Include <malloc-alignment.h> in malloc-size.h after SIZE_SZ is
defined since <malloc-alignment.h> may use SIZE_SZ.

BTW, I kept the trailing '\' since it is used in all other places in
malloc/Makefile.

OK for master?

Thanks.

-- 
H.J.

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From f538de896904ee77c17391af7007a085a40235a1 Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Thu, 8 Jul 2021 20:48:14 -0700
Subject: [PATCH v2] Add a generic malloc test for MALLOC_ALIGNMENT

Changes in the v2 patch

1. Add a comment in malloc/tst-mallocalign1.c to indicate that it is
used to verify that MALLOC_ALIGNMENT is honored by malloc.
2. Include <malloc-alignment.h> in malloc-size.h after SIZE_SZ is
defined since <malloc-alignment.h> may use SIZE_SZ.

BTW, I kept the trailing '\' since it is used all other places in
malloc/Makefile.

H.J.
---
1. Add sysdeps/generic/malloc-size.h to define size related macros for
malloc.
2. Move x86_64/tst-mallocalign1.c malloc and replace ALIGN_MASK with
MALLOC_ALIGN_MASK.
---
 malloc/Makefile                               |  1 +
 malloc/malloc-internal.h                      | 41 +-----------
 {sysdeps/x86_64 => malloc}/tst-mallocalign1.c | 31 +++++----
 sysdeps/generic/malloc-machine.h              |  1 -
 sysdeps/generic/malloc-size.h                 | 64 +++++++++++++++++++
 sysdeps/x86_64/Makefile                       |  4 --
 6 files changed, 81 insertions(+), 61 deletions(-)
 rename {sysdeps/x86_64 => malloc}/tst-mallocalign1.c (65%)
 create mode 100644 sysdeps/generic/malloc-size.h

diff --git a/malloc/Makefile b/malloc/Makefile
index 37a9a4efab..b685ed6d61 100644
--- a/malloc/Makefile
+++ b/malloc/Makefile
@@ -42,6 +42,7 @@ tests := mallocbug tst-malloc tst-valloc tst-calloc tst-obstack \
 	 tst-malloc-stats-cancellation \
 	 tst-tcfree1 tst-tcfree2 tst-tcfree3 \
 	 tst-safe-linking \
+	 tst-mallocalign1 \
 
 tests-static := \
 	 tst-interpose-static-nothread \
diff --git a/malloc/malloc-internal.h b/malloc/malloc-internal.h
index 258f29584e..0c7b5a183c 100644
--- a/malloc/malloc-internal.h
+++ b/malloc/malloc-internal.h
@@ -21,46 +21,7 @@
 
 #include <malloc-machine.h>
 #include <malloc-sysdep.h>
-
-/* INTERNAL_SIZE_T is the word-size used for internal bookkeeping of
-   chunk sizes.
-
-   The default version is the same as size_t.
-
-   While not strictly necessary, it is best to define this as an
-   unsigned type, even if size_t is a signed type. This may avoid some
-   artificial size limitations on some systems.
-
-   On a 64-bit machine, you may be able to reduce malloc overhead by
-   defining INTERNAL_SIZE_T to be a 32 bit `unsigned int' at the
-   expense of not being able to handle more than 2^32 of malloced
-   space. If this limitation is acceptable, you are encouraged to set
-   this unless you are on a platform requiring 16byte alignments. In
-   this case the alignment requirements turn out to negate any
-   potential advantages of decreasing size_t word size.
-
-   Implementors: Beware of the possible combinations of:
-     - INTERNAL_SIZE_T might be signed or unsigned, might be 32 or 64 bits,
-       and might be the same width as int or as long
-     - size_t might have different width and signedness as INTERNAL_SIZE_T
-     - int and long might be 32 or 64 bits, and might be the same width
-
-   To deal with this, most comparisons and difference computations
-   among INTERNAL_SIZE_Ts should cast them to unsigned long, being
-   aware of the fact that casting an unsigned int to a wider long does
-   not sign-extend. (This also makes checking for negative numbers
-   awkward.) Some of these casts result in harmless compiler warnings
-   on some systems.  */
-#ifndef INTERNAL_SIZE_T
-# define INTERNAL_SIZE_T size_t
-#endif
-
-/* The corresponding word size.  */
-#define SIZE_SZ (sizeof (INTERNAL_SIZE_T))
-
-/* The corresponding bit mask value.  */
-#define MALLOC_ALIGN_MASK (MALLOC_ALIGNMENT - 1)
-
+#include <malloc-size.h>
 
 /* Called in the parent process before a fork.  */
 void __malloc_fork_lock_parent (void) attribute_hidden;
diff --git a/sysdeps/x86_64/tst-mallocalign1.c b/malloc/tst-mallocalign1.c
similarity index 65%
rename from sysdeps/x86_64/tst-mallocalign1.c
rename to malloc/tst-mallocalign1.c
index 33a6375777..294e821afe 100644
--- a/sysdeps/x86_64/tst-mallocalign1.c
+++ b/malloc/tst-mallocalign1.c
@@ -1,4 +1,5 @@
-/* Copyright (C) 2012-2021 Free Software Foundation, Inc.
+/* Verify that MALLOC_ALIGNMENT is honored by malloc.
+   Copyright (C) 2012-2021 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
@@ -17,17 +18,16 @@
 
 #include <stdio.h>
 #include <stdlib.h>
+#include <inttypes.h>
+#include <malloc-size.h>
 
-/* Specified by x86-64 psABI.  */
-#define ALIGN_MASK (16 - 1)
-
-void *
+static void *
 test (size_t s)
 {
   void *p = malloc (s);
 
-  printf ("malloc: %ld, %p: %ld\n", (unsigned long) s, p,
-	  ((unsigned long) p) & ALIGN_MASK);
+  printf ("malloc: %zu, %p: %zu\n", s, p,
+	  ((uintptr_t) p) & MALLOC_ALIGN_MASK);
   return p;
 }
 
@@ -38,35 +38,34 @@ do_test (void)
   int ret = 0;
 
   p = test (2);
-  ret |= (unsigned long) p & ALIGN_MASK;
+  ret |= (uintptr_t) p & MALLOC_ALIGN_MASK;
   free (p);
 
   p = test (8);
-  ret |= (unsigned long) p & ALIGN_MASK;
+  ret |= (uintptr_t) p & MALLOC_ALIGN_MASK;
   free (p);
 
   p = test (13);
-  ret |= (unsigned long) p & ALIGN_MASK;
+  ret |= (uintptr_t) p & MALLOC_ALIGN_MASK;
   free (p);
 
   p = test (16);
-  ret |= (unsigned long) p & ALIGN_MASK;
+  ret |= (uintptr_t) p & MALLOC_ALIGN_MASK;
   free (p);
 
   p = test (23);
-  ret |= (unsigned long) p & ALIGN_MASK;
+  ret |= (uintptr_t) p & MALLOC_ALIGN_MASK;
   free (p);
 
   p = test (43);
-  ret |= (unsigned long) p & ALIGN_MASK;
+  ret |= (uintptr_t) p & MALLOC_ALIGN_MASK;
   free (p);
 
   p = test (123);
-  ret |= (unsigned long) p & ALIGN_MASK;
+  ret |= (uintptr_t) p & MALLOC_ALIGN_MASK;
   free (p);
 
   return ret;
 }
 
-#define TEST_FUNCTION do_test ()
-#include "../test-skeleton.c"
+#include <support/test-driver.c>
diff --git a/sysdeps/generic/malloc-machine.h b/sysdeps/generic/malloc-machine.h
index a71f2361f5..121d8ad0c9 100644
--- a/sysdeps/generic/malloc-machine.h
+++ b/sysdeps/generic/malloc-machine.h
@@ -21,7 +21,6 @@
 #define _GENERIC_MALLOC_MACHINE_H
 
 #include <atomic.h>
-#include <malloc-alignment.h>
 
 #ifndef atomic_full_barrier
 # define atomic_full_barrier() __asm ("" ::: "memory")
diff --git a/sysdeps/generic/malloc-size.h b/sysdeps/generic/malloc-size.h
new file mode 100644
index 0000000000..41901b9a44
--- /dev/null
+++ b/sysdeps/generic/malloc-size.h
@@ -0,0 +1,64 @@
+/* Define INTERNAL_SIZE_T, SIZE_SZ, MALLOC_ALIGNMENT and MALLOC_ALIGN_MASK
+   for malloc.
+   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/>.  */
+
+#ifndef _GENERIC_MALLOC_SIZE_H
+#define _GENERIC_MALLOC_SIZE_H
+
+/* INTERNAL_SIZE_T is the word-size used for internal bookkeeping of
+   chunk sizes.
+
+   The default version is the same as size_t.
+
+   While not strictly necessary, it is best to define this as an
+   unsigned type, even if size_t is a signed type. This may avoid some
+   artificial size limitations on some systems.
+
+   On a 64-bit machine, you may be able to reduce malloc overhead by
+   defining INTERNAL_SIZE_T to be a 32 bit `unsigned int' at the
+   expense of not being able to handle more than 2^32 of malloced
+   space. If this limitation is acceptable, you are encouraged to set
+   this unless you are on a platform requiring 16byte alignments. In
+   this case the alignment requirements turn out to negate any
+   potential advantages of decreasing size_t word size.
+
+   Implementors: Beware of the possible combinations of:
+     - INTERNAL_SIZE_T might be signed or unsigned, might be 32 or 64 bits,
+       and might be the same width as int or as long
+     - size_t might have different width and signedness as INTERNAL_SIZE_T
+     - int and long might be 32 or 64 bits, and might be the same width
+
+   To deal with this, most comparisons and difference computations
+   among INTERNAL_SIZE_Ts should cast them to unsigned long, being
+   aware of the fact that casting an unsigned int to a wider long does
+   not sign-extend. (This also makes checking for negative numbers
+   awkward.) Some of these casts result in harmless compiler warnings
+   on some systems.  */
+#ifndef INTERNAL_SIZE_T
+# define INTERNAL_SIZE_T size_t
+#endif
+
+/* The corresponding word size.  */
+#define SIZE_SZ (sizeof (INTERNAL_SIZE_T))
+
+#include <malloc-alignment.h>
+
+/* The corresponding bit mask value.  */
+#define MALLOC_ALIGN_MASK (MALLOC_ALIGNMENT - 1)
+
+#endif /* _GENERIC_MALLOC_SIZE_H */
diff --git a/sysdeps/x86_64/Makefile b/sysdeps/x86_64/Makefile
index 3fc03f4a19..22c5b63ab5 100644
--- a/sysdeps/x86_64/Makefile
+++ b/sysdeps/x86_64/Makefile
@@ -13,10 +13,6 @@ sysdep_routines += _mcount
 sysdep_noprof += _mcount
 endif
 
-ifeq ($(subdir),malloc)
-tests += tst-mallocalign1
-endif
-
 ifeq ($(subdir),string)
 sysdep_routines += strcasecmp_l-nonascii strncase_l-nonascii
 gen-as-const-headers += locale-defines.sym
-- 
2.31.1