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From a107bd201f836b1d82e1a9086a2a48625ac1c0dd Mon Sep 17 00:00:00 2001
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From: "H.J. Lu" <hjl.tools@gmail.com>
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Date: Wed, 2 Mar 2022 13:52:42 -0800
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Subject: [PATCH] x86-64 memcmp/wmemcmp: Properly handle the length parameter
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 [BZ #24097]
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On x32, the size_t parameter may be passed in the lower 32 bits of a
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64-bit register with the non-zero upper 32 bits.  The string/memory
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functions written in assembly can only use the lower 32 bits of a
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64-bit register as length or must clear the upper 32 bits before using
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the full 64-bit register for length.
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This pach fixes memcmp/wmemcmp for x32.  Tested on x86-64 and x32.  On
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x86-64, libc.so is the same with and withou the fix.
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	[BZ #24097]
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	CVE-2019-6488
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	* sysdeps/x86_64/multiarch/memcmp-avx2-movbe.S: Use RDX_LP for
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	length.  Clear the upper 32 bits of RDX register.
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	* sysdeps/x86_64/multiarch/memcmp-sse4.S: Likewise.
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	* sysdeps/x86_64/multiarch/memcmp-ssse3.S: Likewise.
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	* sysdeps/x86_64/x32/Makefile (tests): Add tst-size_t-memcmp and
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	tst-size_t-wmemcmp.
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	* sysdeps/x86_64/x32/tst-size_t-memcmp.c: New file.
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	* sysdeps/x86_64/x32/tst-size_t-wmemcmp.c: Likewise.
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(cherry picked from commit b304fc201d2f6baf52ea790df8643e99772243cd)
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---
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 sysdeps/x86_64/multiarch/memcmp-avx2-movbe.S |  7 +-
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 sysdeps/x86_64/multiarch/memcmp-sse4.S       |  9 ++-
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 sysdeps/x86_64/multiarch/memcmp-ssse3.S      |  7 +-
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 sysdeps/x86_64/x32/Makefile                  |  4 +-
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 sysdeps/x86_64/x32/tst-size_t-memcmp.c       | 76 ++++++++++++++++++++
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 sysdeps/x86_64/x32/tst-size_t-wmemcmp.c      | 20 ++++++
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 6 files changed, 114 insertions(+), 9 deletions(-)
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 create mode 100644 sysdeps/x86_64/x32/tst-size_t-memcmp.c
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 create mode 100644 sysdeps/x86_64/x32/tst-size_t-wmemcmp.c
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diff --git a/sysdeps/x86_64/multiarch/memcmp-avx2-movbe.S b/sysdeps/x86_64/multiarch/memcmp-avx2-movbe.S
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index 30f764c3..e3a35b89 100644
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--- a/sysdeps/x86_64/multiarch/memcmp-avx2-movbe.S
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+++ b/sysdeps/x86_64/multiarch/memcmp-avx2-movbe.S
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@@ -58,9 +58,12 @@
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 	.section .text.avx,"ax",@progbits
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 ENTRY (MEMCMP)
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 # ifdef USE_AS_WMEMCMP
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-	shl	$2, %rdx
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+	shl	$2, %RDX_LP
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+# elif defined __ILP32__
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+	/* Clear the upper 32 bits.  */
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+	movl	%edx, %edx
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 # endif
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-	cmpq	$VEC_SIZE, %rdx
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+	cmp	$VEC_SIZE, %RDX_LP
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 	jb	L(less_vec)
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 	/* From VEC to 2 * VEC.  No branch when size == VEC_SIZE.  */
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diff --git a/sysdeps/x86_64/multiarch/memcmp-sse4.S b/sysdeps/x86_64/multiarch/memcmp-sse4.S
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index 8e164f2c..302900f5 100644
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--- a/sysdeps/x86_64/multiarch/memcmp-sse4.S
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+++ b/sysdeps/x86_64/multiarch/memcmp-sse4.S
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@@ -42,13 +42,16 @@
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 	.section .text.sse4.1,"ax",@progbits
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 ENTRY (MEMCMP)
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 # ifdef USE_AS_WMEMCMP
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-	shl	$2, %rdx
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+	shl	$2, %RDX_LP
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+# elif defined __ILP32__
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+	/* Clear the upper 32 bits.  */
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+	mov	%edx, %edx
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 # endif
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 	pxor	%xmm0, %xmm0
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-	cmp	$79, %rdx
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+	cmp	$79, %RDX_LP
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 	ja	L(79bytesormore)
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 # ifndef USE_AS_WMEMCMP
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-	cmp	$1, %rdx
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+	cmp	$1, %RDX_LP
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 	je	L(firstbyte)
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 # endif
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 	add	%rdx, %rsi
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diff --git a/sysdeps/x86_64/multiarch/memcmp-ssse3.S b/sysdeps/x86_64/multiarch/memcmp-ssse3.S
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index 6f76c641..69d030fc 100644
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--- a/sysdeps/x86_64/multiarch/memcmp-ssse3.S
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+++ b/sysdeps/x86_64/multiarch/memcmp-ssse3.S
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@@ -33,9 +33,12 @@
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 	atom_text_section
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 ENTRY (MEMCMP)
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 # ifdef USE_AS_WMEMCMP
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-	shl	$2, %rdx
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-	test	%rdx, %rdx
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+	shl	$2, %RDX_LP
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+	test	%RDX_LP, %RDX_LP
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 	jz	L(equal)
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+# elif defined __ILP32__
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+	/* Clear the upper 32 bits.  */
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+	mov	%edx, %edx
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 # endif
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 	mov	%rdx, %rcx
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 	mov	%rdi, %rdx
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diff --git a/sysdeps/x86_64/x32/Makefile b/sysdeps/x86_64/x32/Makefile
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index 7d528889..ddec7f04 100644
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--- a/sysdeps/x86_64/x32/Makefile
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+++ b/sysdeps/x86_64/x32/Makefile
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@@ -6,9 +6,9 @@ CFLAGS-s_llround.c += -fno-builtin-lround
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 endif
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 ifeq ($(subdir),string)
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-tests += tst-size_t-memchr
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+tests += tst-size_t-memchr tst-size_t-memcmp
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 endif
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 ifeq ($(subdir),wcsmbs)
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-tests += tst-size_t-wmemchr
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+tests += tst-size_t-wmemchr tst-size_t-wmemcmp
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 endif
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diff --git a/sysdeps/x86_64/x32/tst-size_t-memcmp.c b/sysdeps/x86_64/x32/tst-size_t-memcmp.c
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new file mode 100644
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index 00000000..9bd6fdb4
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--- /dev/null
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+++ b/sysdeps/x86_64/x32/tst-size_t-memcmp.c
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@@ -0,0 +1,76 @@
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+/* Test memcmp with size_t in the lower 32 bits of 64-bit register.
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+   Copyright (C) 2019 Free Software Foundation, Inc.
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+   This file is part of the GNU C Library.
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+
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+   The GNU C Library is free software; you can redistribute it and/or
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+   modify it under the terms of the GNU Lesser General Public
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+   License as published by the Free Software Foundation; either
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+   version 2.1 of the License, or (at your option) any later version.
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+
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+   The GNU C Library is distributed in the hope that it will be useful,
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+   but WITHOUT ANY WARRANTY; without even the implied warranty of
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+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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+   Lesser General Public License for more details.
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+
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+   You should have received a copy of the GNU Lesser General Public
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+   License along with the GNU C Library; if not, see
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+   <http://www.gnu.org/licenses/>.  */
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+
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+#define TEST_MAIN
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+#ifdef WIDE
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+# define TEST_NAME "wmemcmp"
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+#else
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+# define TEST_NAME "memcmp"
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+#endif
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+
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+#include "test-size_t.h"
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+
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+#ifdef WIDE
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+# include <inttypes.h>
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+# include <wchar.h>
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+
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+# define MEMCMP wmemcmp
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+# define CHAR wchar_t
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+#else
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+# define MEMCMP memcmp
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+# define CHAR char
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+#endif
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+
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+IMPL (MEMCMP, 1)
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+
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+typedef int (*proto_t) (const CHAR *, const CHAR *, size_t);
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+
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+static int
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+__attribute__ ((noinline, noclone))
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+do_memcmp (parameter_t a, parameter_t b)
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+{
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+  return CALL (&b, a.p, b.p, a.len);
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+}
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+
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+static int
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+test_main (void)
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+{
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+  test_init ();
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+
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+  parameter_t dest = { { page_size / sizeof (CHAR) }, buf1 };
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+  parameter_t src = { { 0 }, buf2 };
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+
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+  memcpy (buf1, buf2, page_size);
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+
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+  int ret = 0;
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+  FOR_EACH_IMPL (impl, 0)
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+    {
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+      src.fn = impl->fn;
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+      int res = do_memcmp (dest, src);
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+      if (res)
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+	{
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+	  error (0, 0, "Wrong result in function %s: %i != 0",
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+		 impl->name, res);
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+	  ret = 1;
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+	}
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+    }
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+
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+  return ret ? EXIT_FAILURE : EXIT_SUCCESS;
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+}
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+
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+#include <support/test-driver.c>
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diff --git a/sysdeps/x86_64/x32/tst-size_t-wmemcmp.c b/sysdeps/x86_64/x32/tst-size_t-wmemcmp.c
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new file mode 100644
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index 00000000..e8b5ffd0
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--- /dev/null
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+++ b/sysdeps/x86_64/x32/tst-size_t-wmemcmp.c
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@@ -0,0 +1,20 @@
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+/* Test wmemcmp with size_t in the lower 32 bits of 64-bit register.
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+   Copyright (C) 2019 Free Software Foundation, Inc.
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+   This file is part of the GNU C Library.
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+
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+   The GNU C Library is free software; you can redistribute it and/or
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+   modify it under the terms of the GNU Lesser General Public
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+   License as published by the Free Software Foundation; either
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+   version 2.1 of the License, or (at your option) any later version.
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+
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+   The GNU C Library is distributed in the hope that it will be useful,
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+   but WITHOUT ANY WARRANTY; without even the implied warranty of
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+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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+   Lesser General Public License for more details.
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+
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+   You should have received a copy of the GNU Lesser General Public
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+   License along with the GNU C Library; if not, see
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+   <http://www.gnu.org/licenses/>.  */
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+
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+#define WIDE 1
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+#include "tst-size_t-memcmp.c"
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-- 
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GitLab
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