S390: Refactor strnlen ifunc handling.

The ifunc handling for strnlen is adjusted in order to omit ifunc
variants if those will never be used as the minimum architecture level
already supports newer CPUs by default.
Glibc internal calls will then also use the "newer" ifunc variant.

ChangeLog:

	* sysdeps/s390/multiarch/Makefile
	(sysdep_routines): Remove strnlen variants.
	* sysdeps/s390/Makefile (sysdep_routines): Add strnlen variants.
	* sysdeps/s390/multiarch/ifunc-impl-list.c
	(__libc_ifunc_impl_list): Refactor ifunc handling for strnlen.
	* sysdeps/s390/multiarch/strnlen-c.c: Move to ...
	* sysdeps/s390/strnlen-c.c: ... here and adjust ifunc handling.
	* sysdeps/s390/multiarch/strnlen-vx.S: Move to ...
	* sysdeps/s390/strnlen-vx.S: ... here and adjust ifunc handling.
	* sysdeps/s390/multiarch/strnlen.c: Move to ...
	* sysdeps/s390/strnlen.c: ... here and adjust ifunc handling.
	* sysdeps/s390/ifunc-strnlen.h: New file.

7 files changed, 113 insertions, 21 deletions

diff --git a/sysdeps/s390/Makefile b/sysdeps/s390/Makefile
index bc21b06825..4390af56b3 100644
--- a/sysdeps/s390/Makefile
+++ b/sysdeps/s390/Makefile
@@ -60,5 +60,6 @@ sysdep_routines += bzero memset memset-z900 \
 		   memmove memmove-c \
 		   strstr strstr-vx strstr-c \
 		   memmem memmem-vx memmem-c \
-		   strlen strlen-vx strlen-c
+		   strlen strlen-vx strlen-c \
+		   strnlen strnlen-vx strnlen-c
 endif
diff --git a/sysdeps/s390/ifunc-strnlen.h b/sysdeps/s390/ifunc-strnlen.h
new file mode 100644
index 0000000000..e923298887
--- /dev/null
+++ b/sysdeps/s390/ifunc-strnlen.h
@@ -0,0 +1,52 @@
+/* strnlen variant information on S/390 version.
+   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/>.  */
+
+#if defined USE_MULTIARCH && IS_IN (libc)		\
+  && ! defined HAVE_S390_MIN_Z13_ZARCH_ASM_SUPPORT
+# define HAVE_STRNLEN_IFUNC	1
+#else
+# define HAVE_STRNLEN_IFUNC	0
+#endif
+
+#ifdef HAVE_S390_VX_ASM_SUPPORT
+# define HAVE_STRNLEN_IFUNC_AND_VX_SUPPORT HAVE_STRNLEN_IFUNC
+#else
+# define HAVE_STRNLEN_IFUNC_AND_VX_SUPPORT 0
+#endif
+
+#if defined HAVE_S390_MIN_Z13_ZARCH_ASM_SUPPORT
+# define STRNLEN_DEFAULT	STRNLEN_Z13
+# define HAVE_STRNLEN_C		0
+# define HAVE_STRNLEN_Z13	1
+#else
+# define STRNLEN_DEFAULT	STRNLEN_C
+# define HAVE_STRNLEN_C		1
+# define HAVE_STRNLEN_Z13	HAVE_STRNLEN_IFUNC_AND_VX_SUPPORT
+#endif
+
+#if HAVE_STRNLEN_C
+# define STRNLEN_C		__strnlen_c
+#else
+# define STRNLEN_C		NULL
+#endif
+
+#if HAVE_STRNLEN_Z13
+# define STRNLEN_Z13		__strnlen_vx
+#else
+# define STRNLEN_Z13		NULL
+#endif
diff --git a/sysdeps/s390/multiarch/Makefile b/sysdeps/s390/multiarch/Makefile
index 601523919c..35ba223c5d 100644
--- a/sysdeps/s390/multiarch/Makefile
+++ b/sysdeps/s390/multiarch/Makefile
@@ -1,6 +1,5 @@
 ifeq ($(subdir),string)
-sysdep_routines += strnlen strnlen-vx strnlen-c \
-		   strcpy strcpy-vx \
+sysdep_routines += strcpy strcpy-vx \
 		   stpcpy stpcpy-vx stpcpy-c \
 		   strncpy strncpy-vx \
 		   stpncpy stpncpy-vx stpncpy-c \
diff --git a/sysdeps/s390/multiarch/ifunc-impl-list.c b/sysdeps/s390/multiarch/ifunc-impl-list.c
index c531be4bc7..680e5b738b 100644
--- a/sysdeps/s390/multiarch/ifunc-impl-list.c
+++ b/sysdeps/s390/multiarch/ifunc-impl-list.c
@@ -27,6 +27,7 @@
 #include <ifunc-strstr.h>
 #include <ifunc-memmem.h>
 #include <ifunc-strlen.h>
+#include <ifunc-strnlen.h>
 
 /* Maximum number of IFUNC implementations.  */
 #define MAX_IFUNC	3
@@ -177,6 +178,18 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
 		)
 #endif /* HAVE_STRLEN_IFUNC  */
 
+#if HAVE_STRNLEN_IFUNC
+    IFUNC_IMPL (i, name, strnlen,
+# if HAVE_STRNLEN_Z13
+		IFUNC_IMPL_ADD (array, i, strnlen,
+				dl_hwcap & HWCAP_S390_VX, STRNLEN_Z13)
+# endif
+# if HAVE_STRNLEN_C
+		IFUNC_IMPL_ADD (array, i, strnlen, 1, STRNLEN_C)
+# endif
+		)
+#endif /* HAVE_STRNLEN_IFUNC  */
+
 #ifdef HAVE_S390_VX_ASM_SUPPORT
 
 # define IFUNC_VX_IMPL(FUNC)						\
@@ -187,7 +200,6 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
 
   IFUNC_VX_IMPL (wcslen);
 
-  IFUNC_VX_IMPL (strnlen);
   IFUNC_VX_IMPL (wcsnlen);
 
   IFUNC_VX_IMPL (strcpy);
diff --git a/sysdeps/s390/multiarch/strnlen-c.c b/sysdeps/s390/strnlen-c.c
index 353e83ed35..c2d887f1e4 100644
--- a/sysdeps/s390/multiarch/strnlen-c.c
+++ b/sysdeps/s390/strnlen-c.c
@@ -16,15 +16,19 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
-#if defined HAVE_S390_VX_ASM_SUPPORT && IS_IN (libc)
-# define STRNLEN  __strnlen_c
-# ifdef SHARED
-#  undef libc_hidden_def
-#  define libc_hidden_def(name)					\
+#include <ifunc-strnlen.h>
+
+#if HAVE_STRNLEN_C
+# if HAVE_STRNLEN_IFUNC
+#  define STRNLEN STRNLEN_C
+#  if defined SHARED && IS_IN (libc)
+#   undef libc_hidden_def
+#   define libc_hidden_def(name)					\
   __hidden_ver1 (__strnlen_c, __GI_strnlen, __strnlen_c);	\
   strong_alias (__strnlen_c, __strnlen_c_1);			\
   __hidden_ver1 (__strnlen_c_1, __GI___strnlen, __strnlen_c_1);
-# endif /* SHARED */
+#  endif
+# endif
 
 # include <string/strnlen.c>
-#endif /* HAVE_S390_VX_ASM_SUPPORT && IS_IN (libc) */
+#endif
diff --git a/sysdeps/s390/multiarch/strnlen-vx.S b/sysdeps/s390/strnlen-vx.S
index fc659a956c..0b8fe3da34 100644
--- a/sysdeps/s390/multiarch/strnlen-vx.S
+++ b/sysdeps/s390/strnlen-vx.S
@@ -16,7 +16,9 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
-#if defined HAVE_S390_VX_ASM_SUPPORT && IS_IN (libc)
+#include <ifunc-strnlen.h>
+
+#if HAVE_STRNLEN_Z13
 
 # include "sysdep.h"
 # include "asm-syntax.h"
@@ -34,7 +36,7 @@
    -r5=current_len and return_value
    -v16=part of s
 */
-ENTRY(__strnlen_vx)
+ENTRY(STRNLEN_Z13)
 	.machine "z13"
 	.machinemode "zarch_nohighgprs"
 
@@ -130,5 +132,16 @@ ENTRY(__strnlen_vx)
 	clgrjl	%r1,%r3,.Lloop64
 
 	j	.Llt64
-END(__strnlen_vx)
-#endif /* HAVE_S390_VX_ASM_SUPPORT && IS_IN (libc) */
+END(STRNLEN_Z13)
+
+# if ! HAVE_STRNLEN_IFUNC
+strong_alias (STRNLEN_Z13, __strnlen)
+weak_alias (__strnlen, strnlen)
+# endif
+
+# if ! HAVE_STRNLEN_C && defined SHARED && IS_IN (libc)
+strong_alias (STRNLEN_Z13, __GI_strnlen)
+strong_alias (STRNLEN_Z13, __GI___strnlen)
+# endif
+
+#endif /* HAVE_STRNLEN_Z13  */
diff --git a/sysdeps/s390/multiarch/strnlen.c b/sysdeps/s390/strnlen.c
index 0f9cff5d69..aa4953d503 100644
--- a/sysdeps/s390/multiarch/strnlen.c
+++ b/sysdeps/s390/strnlen.c
@@ -16,7 +16,9 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
-#if defined HAVE_S390_VX_ASM_SUPPORT && IS_IN (libc)
+#include <ifunc-strnlen.h>
+
+#if HAVE_STRNLEN_IFUNC
 # define strnlen __redirect_strnlen
 # define __strnlen __redirect___strnlen
 # include <string.h>
@@ -24,9 +26,18 @@
 # undef __strnlen
 # include <ifunc-resolve.h>
 
-s390_vx_libc_ifunc_redirected (__redirect___strnlen, __strnlen)
-weak_alias (__strnlen, strnlen)
+# if HAVE_STRNLEN_C
+extern __typeof (__redirect_strnlen) STRNLEN_C attribute_hidden;
+# endif
 
-#else
-# include <string/strnlen.c>
-#endif /* !(defined HAVE_S390_VX_ASM_SUPPORT && IS_IN (libc)) */
+# if HAVE_STRNLEN_Z13
+extern __typeof (__redirect_strnlen) STRNLEN_Z13 attribute_hidden;
+# endif
+
+s390_libc_ifunc_expr (__redirect___strnlen, __strnlen,
+		      (HAVE_STRNLEN_Z13 && (hwcap & HWCAP_S390_VX))
+		      ? STRNLEN_Z13
+		      : STRNLEN_DEFAULT
+		      )
+weak_alias (__strnlen, strnlen)
+#endif /* HAVE_STRNLEN_IFUNC  */