Merge branch release/2.30/master into ibm/2.30/masteribm/2.30/master

21 files changed, 681 insertions, 284 deletions

diff --git a/NEWS b/NEWS
index f7501ac415..64fa988e42 100644
--- a/NEWS
+++ b/NEWS
@@ -74,7 +74,10 @@ The following bugs are resolved with this release:
   [27130] "rep movsb" performance issue
   [27177] GLIBC_TUNABLES=glibc.cpu.x86_ibt=on:glibc.cpu.x86_shstk=on doesn't work
   [27457] vzeroupper use in AVX2 multiarch string functions cause HTM aborts
+  [27974] Overflow bug in some implementation of wcsnlen, wmemchr, and wcsncat
   [28755] overflow bug in wcsncmp_avx2 and wcsncmp_evex
+  [28896] strncmp-avx2-rtm and wcsncmp-avx2-rtm fallback on non-rtm
+    variants when avoiding overflow
 
 
 Version 2.30
diff --git a/string/test-memchr.c b/string/test-memchr.c
index 58bb54efbc..32582fde7c 100644
--- a/string/test-memchr.c
+++ b/string/test-memchr.c
@@ -65,8 +65,8 @@ do_one_test (impl_t *impl, const CHAR *s, int c, size_t n, CHAR *exp_res)
   CHAR *res = CALL (impl, s, c, n);
   if (res != exp_res)
     {
-      error (0, 0, "Wrong result in function %s %p %p", impl->name,
-	     res, exp_res);
+      error (0, 0, "Wrong result in function %s (%p, %d, %zu) -> %p != %p",
+             impl->name, s, c, n, res, exp_res);
       ret = 1;
       return;
     }
@@ -91,7 +91,7 @@ do_test (size_t align, size_t pos, size_t len, size_t n, int seek_char)
     }
   buf[align + len] = 0;
 
-  if (pos < len)
+  if (pos < MIN(n, len))
     {
       buf[align + pos] = seek_char;
       buf[align + len] = -seek_char;
@@ -108,6 +108,38 @@ do_test (size_t align, size_t pos, size_t len, size_t n, int seek_char)
 }
 
 static void
+do_overflow_tests (void)
+{
+  size_t i, j, len;
+  const size_t one = 1;
+  uintptr_t buf_addr = (uintptr_t) buf1;
+
+  for (i = 0; i < 750; ++i)
+    {
+        do_test (0, i, 751, SIZE_MAX - i, BIG_CHAR);
+        do_test (0, i, 751, i - buf_addr, BIG_CHAR);
+        do_test (0, i, 751, -buf_addr - i, BIG_CHAR);
+        do_test (0, i, 751, SIZE_MAX - buf_addr - i, BIG_CHAR);
+        do_test (0, i, 751, SIZE_MAX - buf_addr + i, BIG_CHAR);
+
+      len = 0;
+      for (j = 8 * sizeof(size_t) - 1; j ; --j)
+        {
+          len |= one << j;
+          do_test (0, i, 751, len - i, BIG_CHAR);
+          do_test (0, i, 751, len + i, BIG_CHAR);
+          do_test (0, i, 751, len - buf_addr - i, BIG_CHAR);
+          do_test (0, i, 751, len - buf_addr + i, BIG_CHAR);
+
+          do_test (0, i, 751, ~len - i, BIG_CHAR);
+          do_test (0, i, 751, ~len + i, BIG_CHAR);
+          do_test (0, i, 751, ~len - buf_addr - i, BIG_CHAR);
+          do_test (0, i, 751, ~len - buf_addr + i, BIG_CHAR);
+        }
+    }
+}
+
+static void
 do_random_tests (void)
 {
   size_t i, j, n, align, pos, len;
@@ -221,6 +253,7 @@ test_main (void)
     do_test (page_size / 2 - i, i, i, 1, 0x9B);
 
   do_random_tests ();
+  do_overflow_tests ();
   return ret;
 }
 
diff --git a/string/test-strncat.c b/string/test-strncat.c
index 4b71f4a5b7..b9c8c57333 100644
--- a/string/test-strncat.c
+++ b/string/test-strncat.c
@@ -135,6 +135,66 @@ do_test (size_t align1, size_t align2, size_t len1, size_t len2,
 }
 
 static void
+do_overflow_tests (void)
+{
+  size_t i, j, len;
+  const size_t one = 1;
+  CHAR *s1, *s2;
+  uintptr_t s1_addr;
+  s1 = (CHAR *) buf1;
+  s2 = (CHAR *) buf2;
+  s1_addr = (uintptr_t)s1;
+ for (j = 0; j < 200; ++j)
+      s2[j] = 32 + 23 * j % (BIG_CHAR - 32);
+ s2[200] = 0;
+  for (i = 0; i < 750; ++i) {
+    for (j = 0; j < i; ++j)
+      s1[j] = 32 + 23 * j % (BIG_CHAR - 32);
+    s1[i] = '\0';
+
+       FOR_EACH_IMPL (impl, 0)
+    {
+      s2[200] = '\0';
+      do_one_test (impl, s2, s1, SIZE_MAX - i);
+      s2[200] = '\0';
+      do_one_test (impl, s2, s1, i - s1_addr);
+      s2[200] = '\0';
+      do_one_test (impl, s2, s1, -s1_addr - i);
+      s2[200] = '\0';
+      do_one_test (impl, s2, s1, SIZE_MAX - s1_addr - i);
+      s2[200] = '\0';
+      do_one_test (impl, s2, s1, SIZE_MAX - s1_addr + i);
+    }
+
+    len = 0;
+    for (j = 8 * sizeof(size_t) - 1; j ; --j)
+      {
+        len |= one << j;
+        FOR_EACH_IMPL (impl, 0)
+          {
+            s2[200] = '\0';
+            do_one_test (impl, s2, s1, len - i);
+            s2[200] = '\0';
+            do_one_test (impl, s2, s1, len + i);
+            s2[200] = '\0';
+            do_one_test (impl, s2, s1, len - s1_addr - i);
+            s2[200] = '\0';
+            do_one_test (impl, s2, s1, len - s1_addr + i);
+
+            s2[200] = '\0';
+            do_one_test (impl, s2, s1, ~len - i);
+            s2[200] = '\0';
+            do_one_test (impl, s2, s1, ~len + i);
+            s2[200] = '\0';
+            do_one_test (impl, s2, s1, ~len - s1_addr - i);
+            s2[200] = '\0';
+            do_one_test (impl, s2, s1, ~len - s1_addr + i);
+          }
+      }
+  }
+}
+
+static void
 do_random_tests (void)
 {
   size_t i, j, n, align1, align2, len1, len2, N;
@@ -316,6 +376,7 @@ test_main (void)
     }
 
   do_random_tests ();
+  do_overflow_tests ();
   return ret;
 }
 
diff --git a/string/test-strncmp.c b/string/test-strncmp.c
index 042e85e399..af071bd847 100644
--- a/string/test-strncmp.c
+++ b/string/test-strncmp.c
@@ -403,6 +403,18 @@ check2 (void)
   free (s2);
 }
 
+static void
+check3 (void)
+{
+  const CHAR *s1 = L ("abc");
+  CHAR *s2 = STRDUP (s1);
+
+  FOR_EACH_IMPL (impl, 0)
+    check_result (impl, s1, s2, SIZE_MAX, 0);
+
+  free (s2);
+}
+
 int
 test_main (void)
 {
@@ -412,6 +424,7 @@ test_main (void)
 
   check1 ();
   check2 ();
+  check3 ();
 
   printf ("%23s", "");
   FOR_EACH_IMPL (impl, 0)
diff --git a/string/test-strnlen.c b/string/test-strnlen.c
index f7d0896f47..027b9adca6 100644
--- a/string/test-strnlen.c
+++ b/string/test-strnlen.c
@@ -90,6 +90,38 @@ do_test (size_t align, size_t len, size_t maxlen, int max_char)
 }
 
 static void
+do_overflow_tests (void)
+{
+  size_t i, j, len;
+  const size_t one = 1;
+  uintptr_t buf_addr = (uintptr_t) buf1;
+
+  for (i = 0; i < 750; ++i)
+    {
+      do_test (0, i, SIZE_MAX - i, BIG_CHAR);
+      do_test (0, i, i - buf_addr, BIG_CHAR);
+      do_test (0, i, -buf_addr - i, BIG_CHAR);
+      do_test (0, i, SIZE_MAX - buf_addr - i, BIG_CHAR);
+      do_test (0, i, SIZE_MAX - buf_addr + i, BIG_CHAR);
+
+      len = 0;
+      for (j = 8 * sizeof(size_t) - 1; j ; --j)
+        {
+          len |= one << j;
+          do_test (0, i, len - i, BIG_CHAR);
+          do_test (0, i, len + i, BIG_CHAR);
+          do_test (0, i, len - buf_addr - i, BIG_CHAR);
+          do_test (0, i, len - buf_addr + i, BIG_CHAR);
+
+          do_test (0, i, ~len - i, BIG_CHAR);
+          do_test (0, i, ~len + i, BIG_CHAR);
+          do_test (0, i, ~len - buf_addr - i, BIG_CHAR);
+          do_test (0, i, ~len - buf_addr + i, BIG_CHAR);
+        }
+    }
+}
+
+static void
 do_random_tests (void)
 {
   size_t i, j, n, align, len;
@@ -274,6 +306,7 @@ test_main (void)
   do_random_tests ();
   do_page_tests ();
   do_page_2_tests ();
+  do_overflow_tests ();
   return ret;
 }
 
diff --git a/sysdeps/x86/Makefile b/sysdeps/x86/Makefile
index a93139b790..b7aec5df2b 100644
--- a/sysdeps/x86/Makefile
+++ b/sysdeps/x86/Makefile
@@ -33,7 +33,9 @@ tests += \
   tst-strcpy-rtm \
   tst-strlen-rtm \
   tst-strncmp-rtm \
-  tst-strrchr-rtm
+  tst-strrchr-rtm \
+  tst-wcsncmp-rtm \
+# tests
 
 CFLAGS-tst-memchr-rtm.c += -mrtm
 CFLAGS-tst-memcmp-rtm.c += -mrtm
@@ -43,8 +45,9 @@ CFLAGS-tst-memset-rtm.c += -mrtm
 CFLAGS-tst-strchr-rtm.c += -mrtm
 CFLAGS-tst-strcpy-rtm.c += -mrtm
 CFLAGS-tst-strlen-rtm.c += -mrtm
-CFLAGS-tst-strncmp-rtm.c += -mrtm
+CFLAGS-tst-strncmp-rtm.c += -mrtm -Wno-error
 CFLAGS-tst-strrchr-rtm.c += -mrtm
+CFLAGS-tst-wcsncmp-rtm.c += -mrtm -Wno-error
 endif
 
 ifeq ($(enable-cet),yes)
diff --git a/sysdeps/x86/cpu-features.c b/sysdeps/x86/cpu-features.c
index a4d1eacbe7..91215f8e23 100644
--- a/sysdeps/x86/cpu-features.c
+++ b/sysdeps/x86/cpu-features.c
@@ -333,6 +333,9 @@ init_cpu_features (struct cpu_features *cpu_features)
 
       get_extended_indices (cpu_features);
 
+      if (CPU_FEATURES_CPU_P (cpu_features, RTM_ALWAYS_ABORT))
+	cpu_features->cpuid[index_cpu_RTM].reg_RTM &= ~bit_cpu_RTM;
+
       if (family == 0x06)
 	{
 	  model += extended_model;
@@ -394,11 +397,42 @@ init_cpu_features (struct cpu_features *cpu_features)
 	      break;
 	    }
 
-	 /* Disable TSX on some Haswell processors to avoid TSX on kernels that
-	    weren't updated with the latest microcode package (which disables
-	    broken feature by default).  */
+	 /* Disable TSX on some processors to avoid TSX on kernels that
+	    weren't updated with the latest microcode package (which
+	    disables broken feature by default).  */
 	 switch (model)
 	    {
+	    case 0x55:
+	      if (stepping <= 5)
+		goto disable_tsx;
+	      break;
+	    case 0x8e:
+	      /* NB: Although the errata documents that for model == 0x8e,
+		 only 0xb stepping or lower are impacted, the intention of
+		 the errata was to disable TSX on all client processors on
+		 all steppings.  Include 0xc stepping which is an Intel
+		 Core i7-8665U, a client mobile processor.  */
+	    case 0x9e:
+	      if (stepping > 0xc)
+		break;
+	      /* Fall through.  */
+	    case 0x4e:
+	    case 0x5e:
+	      {
+		/* Disable Intel TSX and enable RTM_ALWAYS_ABORT for
+		   processors listed in:
+
+https://www.intel.com/content/www/us/en/support/articles/000059422/processors.html
+		 */
+disable_tsx:
+		cpu_features->cpuid[index_cpu_HLE].reg_HLE
+		  &= ~bit_cpu_HLE;
+		cpu_features->cpuid[index_cpu_RTM].reg_RTM
+		  &= ~bit_cpu_RTM;
+		cpu_features->cpuid[index_cpu_RTM_ALWAYS_ABORT].reg_RTM_ALWAYS_ABORT
+		  |= bit_cpu_RTM_ALWAYS_ABORT;
+	      }
+	      break;
 	    case 0x3f:
 	      /* Xeon E7 v3 with stepping >= 4 has working TSX.  */
 	      if (stepping >= 4)
diff --git a/sysdeps/x86/cpu-features.h b/sysdeps/x86/cpu-features.h
index ca2924bd95..3599dd89d0 100644
--- a/sysdeps/x86/cpu-features.h
+++ b/sysdeps/x86/cpu-features.h
@@ -499,6 +499,7 @@ extern const struct cpu_features *__get_cpu_features (void)
 #define bit_cpu_AVX512_4VNNIW	(1u << 2)
 #define bit_cpu_AVX512_4FMAPS	(1u << 3)
 #define bit_cpu_FSRM		(1u << 4)
+#define bit_cpu_RTM_ALWAYS_ABORT (1u << 11)
 #define bit_cpu_PCONFIG		(1u << 18)
 #define bit_cpu_IBT		(1u << 20)
 #define bit_cpu_IBRS_IBPB	(1u << 26)
@@ -667,6 +668,7 @@ extern const struct cpu_features *__get_cpu_features (void)
 #define index_cpu_AVX512_4VNNIW COMMON_CPUID_INDEX_7
 #define index_cpu_AVX512_4FMAPS	COMMON_CPUID_INDEX_7
 #define index_cpu_FSRM		COMMON_CPUID_INDEX_7
+#define index_cpu_RTM_ALWAYS_ABORT COMMON_CPUID_INDEX_7
 #define index_cpu_PCONFIG	COMMON_CPUID_INDEX_7
 #define index_cpu_IBT		COMMON_CPUID_INDEX_7
 #define index_cpu_IBRS_IBPB	COMMON_CPUID_INDEX_7
@@ -835,6 +837,7 @@ extern const struct cpu_features *__get_cpu_features (void)
 #define reg_AVX512_4VNNIW	edx
 #define reg_AVX512_4FMAPS	edx
 #define reg_FSRM		edx
+#define reg_RTM_ALWAYS_ABORT	edx
 #define reg_PCONFIG		edx
 #define reg_IBT			edx
 #define reg_IBRS_IBPB		edx
diff --git a/sysdeps/x86/tst-get-cpu-features.c b/sysdeps/x86/tst-get-cpu-features.c
index bf2b9b22e7..08aa421fe9 100644
--- a/sysdeps/x86/tst-get-cpu-features.c
+++ b/sysdeps/x86/tst-get-cpu-features.c
@@ -176,6 +176,7 @@ do_test (void)
   CHECK_CPU_FEATURE (AVX512_4VNNIW);
   CHECK_CPU_FEATURE (AVX512_4FMAPS);
   CHECK_CPU_FEATURE (FSRM);
+  CHECK_CPU_FEATURE (RTM_ALWAYS_ABORT);
   CHECK_CPU_FEATURE (PCONFIG);
   CHECK_CPU_FEATURE (IBT);
   CHECK_CPU_FEATURE (IBRS_IBPB);
diff --git a/sysdeps/x86/tst-strncmp-rtm.c b/sysdeps/x86/tst-strncmp-rtm.c
index 236ad951b5..aef9866cf2 100644
--- a/sysdeps/x86/tst-strncmp-rtm.c
+++ b/sysdeps/x86/tst-strncmp-rtm.c
@@ -16,20 +16,35 @@
    License along with the GNU C Library; if not, see
    <https://www.gnu.org/licenses/>.  */
 
+#include <stdint.h>
 #include <tst-string-rtm.h>
 
+#ifdef WIDE
+# define CHAR wchar_t
+# define MEMSET wmemset
+# define STRNCMP wcsncmp
+# define TEST_NAME "wcsncmp"
+#else /* !WIDE */
+# define CHAR char
+# define MEMSET memset
+# define STRNCMP strncmp
+# define TEST_NAME "strncmp"
+#endif /* !WIDE */
+
+
+
 #define LOOP 3000
 #define STRING_SIZE 1024
-char string1[STRING_SIZE];
-char string2[STRING_SIZE];
+CHAR string1[STRING_SIZE];
+CHAR string2[STRING_SIZE];
 
 __attribute__ ((noinline, noclone))
 static int
 prepare (void)
 {
-  memset (string1, 'a', STRING_SIZE - 1);
-  memset (string2, 'a', STRING_SIZE - 1);
-  if (strncmp (string1, string2, STRING_SIZE) == 0)
+  MEMSET (string1, 'a', STRING_SIZE - 1);
+  MEMSET (string2, 'a', STRING_SIZE - 1);
+  if (STRNCMP (string1, string2, STRING_SIZE) == 0)
     return EXIT_SUCCESS;
   else
     return EXIT_FAILURE;
@@ -39,7 +54,17 @@ __attribute__ ((noinline, noclone))
 static int
 function (void)
 {
-  if (strncmp (string1, string2, STRING_SIZE) == 0)
+  if (STRNCMP (string1, string2, STRING_SIZE) == 0)
+    return 0;
+  else
+    return 1;
+}
+
+__attribute__ ((noinline, noclone))
+static int
+function_overflow (void)
+{
+  if (STRNCMP (string1, string2, SIZE_MAX) == 0)
     return 0;
   else
     return 1;
@@ -48,5 +73,9 @@ function (void)
 static int
 do_test (void)
 {
-  return do_test_1 ("strncmp", LOOP, prepare, function);
+  int status = do_test_1 (TEST_NAME, LOOP, prepare, function);
+  if (status != EXIT_SUCCESS)
+    return status;
+  status = do_test_1 (TEST_NAME, LOOP, prepare, function_overflow);
+  return status;
 }
diff --git a/sysdeps/x86/tst-wcsncmp-rtm.c b/sysdeps/x86/tst-wcsncmp-rtm.c
new file mode 100644
index 0000000000..bad3b86378
--- /dev/null
+++ b/sysdeps/x86/tst-wcsncmp-rtm.c
@@ -0,0 +1,21 @@
+/* Test case for wcsncmp inside a transactionally executing RTM region.
+   Copyright (C) 2022 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/>.  */
+
+#define WIDE 1
+#include <wchar.h>
+#include "tst-strncmp-rtm.c"
diff --git a/sysdeps/x86_64/Makefile b/sysdeps/x86_64/Makefile
index d51cf03ac9..b1951adce9 100644
--- a/sysdeps/x86_64/Makefile
+++ b/sysdeps/x86_64/Makefile
@@ -20,6 +20,8 @@ endif
 ifeq ($(subdir),string)
 sysdep_routines += cacheinfo strcasecmp_l-nonascii strncase_l-nonascii
 gen-as-const-headers += locale-defines.sym
+tests += \
+  tst-rsi-strlen
 endif
 
 ifeq ($(subdir),elf)
@@ -150,6 +152,11 @@ ifeq ($(subdir),csu)
 gen-as-const-headers += tlsdesc.sym rtld-offsets.sym
 endif
 
+ifeq ($(subdir),wcsmbs)
+tests += \
+  tst-rsi-wcslen
+endif
+
 $(objpfx)x86_64/tst-x86_64mod-1.os: $(objpfx)tst-x86_64mod-1.os
 	$(make-target-directory)
 	rm -f $@
diff --git a/sysdeps/x86_64/multiarch/ifunc-impl-list.c b/sysdeps/x86_64/multiarch/ifunc-impl-list.c
index e57fb42af3..28971a6b90 100644
--- a/sysdeps/x86_64/multiarch/ifunc-impl-list.c
+++ b/sysdeps/x86_64/multiarch/ifunc-impl-list.c
@@ -657,9 +657,9 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
 			       && HAS_ARCH_FEATURE (AVX512BW_Usable)
 			       && HAS_CPU_FEATURE (BMI2)),
 			      __wcslen_evex)
-	      IFUNC_IMPL_ADD (array, i, wcsnlen,
+	      IFUNC_IMPL_ADD (array, i, wcslen,
 			      CPU_FEATURE_USABLE (SSE4_1),
-			      __wcsnlen_sse4_1)
+			      __wcslen_sse4_1)
 	      IFUNC_IMPL_ADD (array, i, wcslen, 1, __wcslen_sse2))
 
   /* Support sysdeps/x86_64/multiarch/wcsnlen.c.  */
diff --git a/sysdeps/x86_64/multiarch/strcmp-avx2.S b/sysdeps/x86_64/multiarch/strcmp-avx2.S
index f199c91f7f..5c41ba678a 100644
--- a/sysdeps/x86_64/multiarch/strcmp-avx2.S
+++ b/sysdeps/x86_64/multiarch/strcmp-avx2.S
@@ -95,7 +95,7 @@ ENTRY (STRCMP)
 	   length to bound a valid memory region. In these cases just use
 	   'wcscmp'.  */
 	shrq	$56, %rcx
-	jnz	__wcscmp_avx2
+	jnz	OVERFLOW_STRCMP
 #  endif
 	/* Convert units: from wide to byte char.  */
 	shl	$2, %RDX_LP
diff --git a/sysdeps/x86_64/multiarch/strlen-evex.S b/sysdeps/x86_64/multiarch/strlen-evex.S
index 0583819078..4bf6874b82 100644
--- a/sysdeps/x86_64/multiarch/strlen-evex.S
+++ b/sysdeps/x86_64/multiarch/strlen-evex.S
@@ -29,11 +29,13 @@
 # ifdef USE_AS_WCSLEN
 #  define VPCMP		vpcmpd
 #  define VPMINU	vpminud
-#  define SHIFT_REG	r9d
+#  define SHIFT_REG ecx
+#  define CHAR_SIZE	4
 # else
 #  define VPCMP		vpcmpb
 #  define VPMINU	vpminub
-#  define SHIFT_REG	ecx
+#  define SHIFT_REG edx
+#  define CHAR_SIZE	1
 # endif
 
 # define XMMZERO	xmm16
@@ -46,132 +48,165 @@
 # define YMM6		ymm22
 
 # define VEC_SIZE 32
+# define PAGE_SIZE 4096
+# define CHAR_PER_VEC (VEC_SIZE / CHAR_SIZE)
 
 	.section .text.evex,"ax",@progbits
 ENTRY (STRLEN)
 # ifdef USE_AS_STRNLEN
-	/* Check for zero length.  */
+	/* Check zero length.  */
 	test	%RSI_LP, %RSI_LP
 	jz	L(zero)
-#  ifdef USE_AS_WCSLEN
-	shl	$2, %RSI_LP
-#  elif defined __ILP32__
+#  ifdef __ILP32__
 	/* Clear the upper 32 bits.  */
 	movl	%esi, %esi
 #  endif
 	mov	%RSI_LP, %R8_LP
 # endif
-	movl	%edi, %ecx
-	movq	%rdi, %rdx
+	movl	%edi, %eax
 	vpxorq	%XMMZERO, %XMMZERO, %XMMZERO
-
+	/* Clear high bits from edi. Only keeping bits relevant to page
+	   cross check.  */
+	andl	$(PAGE_SIZE - 1), %eax
 	/* Check if we may cross page boundary with one vector load.  */
-	andl	$(2 * VEC_SIZE - 1), %ecx
-	cmpl	$VEC_SIZE, %ecx
-	ja	L(cros_page_boundary)
+	cmpl	$(PAGE_SIZE - VEC_SIZE), %eax
+	ja	L(cross_page_boundary)
 
 	/* Check the first VEC_SIZE bytes.  Each bit in K0 represents a
 	   null byte.  */
 	VPCMP	$0, (%rdi), %YMMZERO, %k0
 	kmovd	%k0, %eax
-	testl	%eax, %eax
-
 # ifdef USE_AS_STRNLEN
-	jnz	L(first_vec_x0_check)
-	/* Adjust length and check the end of data.  */
-	subq	$VEC_SIZE, %rsi
-	jbe	L(max)
-# else
-	jnz	L(first_vec_x0)
+	/* If length < CHAR_PER_VEC handle special.  */
+	cmpq	$CHAR_PER_VEC, %rsi
+	jbe	L(first_vec_x0)
 # endif
-
-	/* Align data for aligned loads in the loop.  */
-	addq	$VEC_SIZE, %rdi
-	andl	$(VEC_SIZE - 1), %ecx
-	andq	$-VEC_SIZE, %rdi
-
+	testl	%eax, %eax
+	jz	L(aligned_more)
+	tzcntl	%eax, %eax
+	ret
 # ifdef USE_AS_STRNLEN
-	/* Adjust length.  */
-	addq	%rcx, %rsi
+L(zero):
+	xorl	%eax, %eax
+	ret
 
-	subq	$(VEC_SIZE * 4), %rsi
-	jbe	L(last_4x_vec_or_less)
+	.p2align 4
+L(first_vec_x0):
+	/* Set bit for max len so that tzcnt will return min of max len
+	   and position of first match.  */
+	btsq	%rsi, %rax
+	tzcntl	%eax, %eax
+	ret
 # endif
-	jmp	L(more_4x_vec)
 
 	.p2align 4
-L(cros_page_boundary):
-	andl	$(VEC_SIZE - 1), %ecx
-	andq	$-VEC_SIZE, %rdi
-
-# ifdef USE_AS_WCSLEN
-	/* NB: Divide shift count by 4 since each bit in K0 represent 4
-	   bytes.  */
-	movl	%ecx, %SHIFT_REG
-	sarl	$2, %SHIFT_REG
+L(first_vec_x1):
+	tzcntl	%eax, %eax
+	/* Safe to use 32 bit instructions as these are only called for
+	   size = [1, 159].  */
+# ifdef USE_AS_STRNLEN
+	/* Use ecx which was computed earlier to compute correct value.
+	 */
+	leal	-(CHAR_PER_VEC * 4 + 1)(%rcx, %rax), %eax
+# else
+	subl	%edx, %edi
+#  ifdef USE_AS_WCSLEN
+	/* NB: Divide bytes by 4 to get the wchar_t count.  */
+	sarl	$2, %edi
+#  endif
+	leal	CHAR_PER_VEC(%rdi, %rax), %eax
 # endif
-	VPCMP	$0, (%rdi), %YMMZERO, %k0
-	kmovd	%k0, %eax
+	ret
 
-	/* Remove the leading bytes.  */
-	sarxl	%SHIFT_REG, %eax, %eax
-	testl	%eax, %eax
-	jz	L(aligned_more)
+	.p2align 4
+L(first_vec_x2):
 	tzcntl	%eax, %eax
-# ifdef USE_AS_WCSLEN
-	/* NB: Multiply wchar_t count by 4 to get the number of bytes.  */
-	sall	$2, %eax
-# endif
+	/* Safe to use 32 bit instructions as these are only called for
+	   size = [1, 159].  */
 # ifdef USE_AS_STRNLEN
-	/* Check the end of data.  */
-	cmpq	%rax, %rsi
-	jbe	L(max)
-# endif
-	addq	%rdi, %rax
-	addq	%rcx, %rax
-	subq	%rdx, %rax
-# ifdef USE_AS_WCSLEN
-	shrq	$2, %rax
+	/* Use ecx which was computed earlier to compute correct value.
+	 */
+	leal	-(CHAR_PER_VEC * 3 + 1)(%rcx, %rax), %eax
+# else
+	subl	%edx, %edi
+#  ifdef USE_AS_WCSLEN
+	/* NB: Divide bytes by 4 to get the wchar_t count.  */
+	sarl	$2, %edi
+#  endif
+	leal	(CHAR_PER_VEC * 2)(%rdi, %rax), %eax
 # endif
 	ret
 
 	.p2align 4
-L(aligned_more):
+L(first_vec_x3):
+	tzcntl	%eax, %eax
+	/* Safe to use 32 bit instructions as these are only called for
+	   size = [1, 159].  */
 # ifdef USE_AS_STRNLEN
-        /* "rcx" is less than VEC_SIZE.  Calculate "rdx + rcx - VEC_SIZE"
-	    with "rdx - (VEC_SIZE - rcx)" instead of "(rdx + rcx) - VEC_SIZE"
-	    to void possible addition overflow.  */
-	negq	%rcx
-	addq	$VEC_SIZE, %rcx
-
-	/* Check the end of data.  */
-	subq	%rcx, %rsi
-	jbe	L(max)
+	/* Use ecx which was computed earlier to compute correct value.
+	 */
+	leal	-(CHAR_PER_VEC * 2 + 1)(%rcx, %rax), %eax
+# else
+	subl	%edx, %edi
+#  ifdef USE_AS_WCSLEN
+	/* NB: Divide bytes by 4 to get the wchar_t count.  */
+	sarl	$2, %edi
+#  endif
+	leal	(CHAR_PER_VEC * 3)(%rdi, %rax), %eax
 # endif
+	ret
 
-	addq	$VEC_SIZE, %rdi
-
+	.p2align 4
+L(first_vec_x4):
+	tzcntl	%eax, %eax
+	/* Safe to use 32 bit instructions as these are only called for
+	   size = [1, 159].  */
 # ifdef USE_AS_STRNLEN
-	subq	$(VEC_SIZE * 4), %rsi
-	jbe	L(last_4x_vec_or_less)
+	/* Use ecx which was computed earlier to compute correct value.
+	 */
+	leal	-(CHAR_PER_VEC + 1)(%rcx, %rax), %eax
+# else
+	subl	%edx, %edi
+#  ifdef USE_AS_WCSLEN
+	/* NB: Divide bytes by 4 to get the wchar_t count.  */
+	sarl	$2, %edi
+#  endif
+	leal	(CHAR_PER_VEC * 4)(%rdi, %rax), %eax
 # endif
+	ret
 
-L(more_4x_vec):
+	.p2align 5
+L(aligned_more):
+	movq	%rdi, %rdx
+	/* Align data to VEC_SIZE.  */
+	andq	$-(VEC_SIZE), %rdi
+L(cross_page_continue):
 	/* Check the first 4 * VEC_SIZE.  Only one VEC_SIZE at a time
 	   since data is only aligned to VEC_SIZE.  */
-	VPCMP	$0, (%rdi), %YMMZERO, %k0
-	kmovd	%k0, %eax
-	testl	%eax, %eax
-	jnz	L(first_vec_x0)
-
+# ifdef USE_AS_STRNLEN
+	/* + CHAR_SIZE because it simplies the logic in
+	   last_4x_vec_or_less.  */
+	leaq	(VEC_SIZE * 5 + CHAR_SIZE)(%rdi), %rcx
+	subq	%rdx, %rcx
+#  ifdef USE_AS_WCSLEN
+	/* NB: Divide bytes by 4 to get the wchar_t count.  */
+	sarl	$2, %ecx
+#  endif
+# endif
+	/* Load first VEC regardless.  */
 	VPCMP	$0, VEC_SIZE(%rdi), %YMMZERO, %k0
+# ifdef USE_AS_STRNLEN
+	/* Adjust length. If near end handle specially.  */
+	subq	%rcx, %rsi
+	jb	L(last_4x_vec_or_less)
+# endif
 	kmovd	%k0, %eax
 	testl	%eax, %eax
 	jnz	L(first_vec_x1)
 
 	VPCMP	$0, (VEC_SIZE * 2)(%rdi), %YMMZERO, %k0
 	kmovd	%k0, %eax
-	testl	%eax, %eax
+	test	%eax, %eax
 	jnz	L(first_vec_x2)
 
 	VPCMP	$0, (VEC_SIZE * 3)(%rdi), %YMMZERO, %k0
@@ -179,258 +214,276 @@ L(more_4x_vec):
 	testl	%eax, %eax
 	jnz	L(first_vec_x3)
 
-	addq	$(VEC_SIZE * 4), %rdi
-
-# ifdef USE_AS_STRNLEN
-	subq	$(VEC_SIZE * 4), %rsi
-	jbe	L(last_4x_vec_or_less)
-# endif
-
-	/* Align data to 4 * VEC_SIZE.  */
-	movq	%rdi, %rcx
-	andl	$(4 * VEC_SIZE - 1), %ecx
-	andq	$-(4 * VEC_SIZE), %rdi
+	VPCMP	$0, (VEC_SIZE * 4)(%rdi), %YMMZERO, %k0
+	kmovd	%k0, %eax
+	testl	%eax, %eax
+	jnz	L(first_vec_x4)
 
+	addq	$VEC_SIZE, %rdi
 # ifdef USE_AS_STRNLEN
-	/* Adjust length.  */
+	/* Check if at last VEC_SIZE * 4 length.  */
+	cmpq	$(CHAR_PER_VEC * 4 - 1), %rsi
+	jbe	L(last_4x_vec_or_less_load)
+	movl	%edi, %ecx
+	andl	$(VEC_SIZE * 4 - 1), %ecx
+#  ifdef USE_AS_WCSLEN
+	/* NB: Divide bytes by 4 to get the wchar_t count.  */
+	sarl	$2, %ecx
+#  endif
+	/* Readjust length.  */
 	addq	%rcx, %rsi
 # endif
+	/* Align data to VEC_SIZE * 4.  */
+	andq	$-(VEC_SIZE * 4), %rdi
 
+	/* Compare 4 * VEC at a time forward.  */
 	.p2align 4
 L(loop_4x_vec):
-	/* Compare 4 * VEC at a time forward.  */
-	VMOVA	(%rdi), %YMM1
-	VMOVA	VEC_SIZE(%rdi), %YMM2
-	VMOVA	(VEC_SIZE * 2)(%rdi), %YMM3
-	VMOVA	(VEC_SIZE * 3)(%rdi), %YMM4
-
-	VPMINU	%YMM1, %YMM2, %YMM5
-	VPMINU	%YMM3, %YMM4, %YMM6
+	/* Load first VEC regardless.  */
+	VMOVA	(VEC_SIZE * 4)(%rdi), %YMM1
+# ifdef USE_AS_STRNLEN
+	/* Break if at end of length.  */
+	subq	$(CHAR_PER_VEC * 4), %rsi
+	jb	L(last_4x_vec_or_less_cmpeq)
+# endif
+	/* Save some code size by microfusing VPMINU with the load. Since
+	   the matches in ymm2/ymm4 can only be returned if there where no
+	   matches in ymm1/ymm3 respectively there is no issue with overlap.
+	 */
+	VPMINU	(VEC_SIZE * 5)(%rdi), %YMM1, %YMM2
+	VMOVA	(VEC_SIZE * 6)(%rdi), %YMM3
+	VPMINU	(VEC_SIZE * 7)(%rdi), %YMM3, %YMM4
+
+	VPCMP	$0, %YMM2, %YMMZERO, %k0
+	VPCMP	$0, %YMM4, %YMMZERO, %k1
+	subq	$-(VEC_SIZE * 4), %rdi
+	kortestd	%k0, %k1
+	jz	L(loop_4x_vec)
+
+	/* Check if end was in first half.  */
+	kmovd	%k0, %eax
+	subq	%rdx, %rdi
+# ifdef USE_AS_WCSLEN
+	shrq	$2, %rdi
+# endif
+	testl	%eax, %eax
+	jz	L(second_vec_return)
 
-	VPMINU	%YMM5, %YMM6, %YMM5
-	VPCMP	$0, %YMM5, %YMMZERO, %k0
-	ktestd	%k0, %k0
-	jnz	L(4x_vec_end)
+	VPCMP	$0, %YMM1, %YMMZERO, %k2
+	kmovd	%k2, %edx
+	/* Combine VEC1 matches (edx) with VEC2 matches (eax).  */
+# ifdef USE_AS_WCSLEN
+	sall	$CHAR_PER_VEC, %eax
+	orl	%edx, %eax
+	tzcntl	%eax, %eax
+# else
+	salq	$CHAR_PER_VEC, %rax
+	orq	%rdx, %rax
+	tzcntq	%rax, %rax
+# endif
+	addq	%rdi, %rax
+	ret
 
-	addq	$(VEC_SIZE * 4), %rdi
 
-# ifndef USE_AS_STRNLEN
-	jmp	L(loop_4x_vec)
-# else
-	subq	$(VEC_SIZE * 4), %rsi
-	ja	L(loop_4x_vec)
+# ifdef USE_AS_STRNLEN
 
+L(last_4x_vec_or_less_load):
+	/* Depending on entry adjust rdi / prepare first VEC in YMM1.  */
+	VMOVA	(VEC_SIZE * 4)(%rdi), %YMM1
+L(last_4x_vec_or_less_cmpeq):
+	VPCMP	$0, %YMM1, %YMMZERO, %k0
+	addq	$(VEC_SIZE * 3), %rdi
 L(last_4x_vec_or_less):
-	/* Less than 4 * VEC and aligned to VEC_SIZE.  */
-	addl	$(VEC_SIZE * 2), %esi
-	jle	L(last_2x_vec)
-
-	VPCMP	$0, (%rdi), %YMMZERO, %k0
 	kmovd	%k0, %eax
+	/* If remaining length > VEC_SIZE * 2. This works if esi is off by
+	   VEC_SIZE * 4.  */
+	testl	$(CHAR_PER_VEC * 2), %esi
+	jnz	L(last_4x_vec)
+
+	/* length may have been negative or positive by an offset of
+	   CHAR_PER_VEC * 4 depending on where this was called from. This
+	   fixes that.  */
+	andl	$(CHAR_PER_VEC * 4 - 1), %esi
 	testl	%eax, %eax
-	jnz	L(first_vec_x0)
+	jnz	L(last_vec_x1_check)
 
-	VPCMP	$0, VEC_SIZE(%rdi), %YMMZERO, %k0
-	kmovd	%k0, %eax
-	testl	%eax, %eax
-	jnz	L(first_vec_x1)
+	/* Check the end of data.  */
+	subl	$CHAR_PER_VEC, %esi
+	jb	L(max)
 
 	VPCMP	$0, (VEC_SIZE * 2)(%rdi), %YMMZERO, %k0
 	kmovd	%k0, %eax
-	testl	%eax, %eax
-	jnz	L(first_vec_x2_check)
-	subl	$VEC_SIZE, %esi
-	jle	L(max)
+	tzcntl	%eax, %eax
+	/* Check the end of data.  */
+	cmpl	%eax, %esi
+	jb	L(max)
 
-	VPCMP	$0, (VEC_SIZE * 3)(%rdi), %YMMZERO, %k0
-	kmovd	%k0, %eax
-	testl	%eax, %eax
-	jnz	L(first_vec_x3_check)
+	subq	%rdx, %rdi
+#  ifdef USE_AS_WCSLEN
+	/* NB: Divide bytes by 4 to get the wchar_t count.  */
+	sarq	$2, %rdi
+#  endif
+	leaq	(CHAR_PER_VEC * 2)(%rdi, %rax), %rax
+	ret
+L(max):
 	movq	%r8, %rax
+	ret
+# endif
+
+	/* Placed here in strnlen so that the jcc L(last_4x_vec_or_less)
+	   in the 4x VEC loop can use 2 byte encoding.  */
+	.p2align 4
+L(second_vec_return):
+	VPCMP	$0, %YMM3, %YMMZERO, %k0
+	/* Combine YMM3 matches (k0) with YMM4 matches (k1).  */
+# ifdef USE_AS_WCSLEN
+	kunpckbw	%k0, %k1, %k0
+	kmovd	%k0, %eax
+	tzcntl	%eax, %eax
+# else
+	kunpckdq	%k0, %k1, %k0
+	kmovq	%k0, %rax
+	tzcntq	%rax, %rax
+# endif
+	leaq	(CHAR_PER_VEC * 2)(%rdi, %rax), %rax
+	ret
+
+
+# ifdef USE_AS_STRNLEN
+L(last_vec_x1_check):
+	tzcntl	%eax, %eax
+	/* Check the end of data.  */
+	cmpl	%eax, %esi
+	jb	L(max)
+	subq	%rdx, %rdi
 #  ifdef USE_AS_WCSLEN
-	shrq	$2, %rax
+	/* NB: Divide bytes by 4 to get the wchar_t count.  */
+	sarq	$2, %rdi
 #  endif
+	leaq	(CHAR_PER_VEC)(%rdi, %rax), %rax
 	ret
 
 	.p2align 4
-L(last_2x_vec):
-	addl	$(VEC_SIZE * 2), %esi
+L(last_4x_vec):
+	/* Test first 2x VEC normally.  */
+	testl	%eax, %eax
+	jnz	L(last_vec_x1)
 
-	VPCMP	$0, (%rdi), %YMMZERO, %k0
+	VPCMP	$0, (VEC_SIZE * 2)(%rdi), %YMMZERO, %k0
 	kmovd	%k0, %eax
 	testl	%eax, %eax
-	jnz	L(first_vec_x0_check)
-	subl	$VEC_SIZE, %esi
-	jle	L(max)
+	jnz	L(last_vec_x2)
 
-	VPCMP	$0, VEC_SIZE(%rdi), %YMMZERO, %k0
+	/* Normalize length.  */
+	andl	$(CHAR_PER_VEC * 4 - 1), %esi
+	VPCMP	$0, (VEC_SIZE * 3)(%rdi), %YMMZERO, %k0
 	kmovd	%k0, %eax
 	testl	%eax, %eax
-	jnz	L(first_vec_x1_check)
-	movq	%r8, %rax
-#  ifdef USE_AS_WCSLEN
-	shrq	$2, %rax
-#  endif
-	ret
+	jnz	L(last_vec_x3)
 
-	.p2align 4
-L(first_vec_x0_check):
+	/* Check the end of data.  */
+	subl	$(CHAR_PER_VEC * 3), %esi
+	jb	L(max)
+
+	VPCMP	$0, (VEC_SIZE * 4)(%rdi), %YMMZERO, %k0
+	kmovd	%k0, %eax
 	tzcntl	%eax, %eax
-#  ifdef USE_AS_WCSLEN
-	/* NB: Multiply wchar_t count by 4 to get the number of bytes.  */
-	sall	$2, %eax
-#  endif
 	/* Check the end of data.  */
-	cmpq	%rax, %rsi
-	jbe	L(max)
-	addq	%rdi, %rax
-	subq	%rdx, %rax
+	cmpl	%eax, %esi
+	jb	L(max_end)
+
+	subq	%rdx, %rdi
 #  ifdef USE_AS_WCSLEN
-	shrq	$2, %rax
+	/* NB: Divide bytes by 4 to get the wchar_t count.  */
+	sarq	$2, %rdi
 #  endif
+	leaq	(CHAR_PER_VEC * 4)(%rdi, %rax), %rax
 	ret
 
 	.p2align 4
-L(first_vec_x1_check):
+L(last_vec_x1):
 	tzcntl	%eax, %eax
+	subq	%rdx, %rdi
 #  ifdef USE_AS_WCSLEN
-	/* NB: Multiply wchar_t count by 4 to get the number of bytes.  */
-	sall	$2, %eax
-#  endif
-	/* Check the end of data.  */
-	cmpq	%rax, %rsi
-	jbe	L(max)
-	addq	$VEC_SIZE, %rax
-	addq	%rdi, %rax
-	subq	%rdx, %rax
-#  ifdef USE_AS_WCSLEN
-	shrq	$2, %rax
+	/* NB: Divide bytes by 4 to get the wchar_t count.  */
+	sarq	$2, %rdi
 #  endif
+	leaq	(CHAR_PER_VEC)(%rdi, %rax), %rax
 	ret
 
 	.p2align 4
-L(first_vec_x2_check):
+L(last_vec_x2):
 	tzcntl	%eax, %eax
+	subq	%rdx, %rdi
 #  ifdef USE_AS_WCSLEN
-	/* NB: Multiply wchar_t count by 4 to get the number of bytes.  */
-	sall	$2, %eax
-#  endif
-	/* Check the end of data.  */
-	cmpq	%rax, %rsi
-	jbe	L(max)
-	addq	$(VEC_SIZE * 2), %rax
-	addq	%rdi, %rax
-	subq	%rdx, %rax
-#  ifdef USE_AS_WCSLEN
-	shrq	$2, %rax
+	/* NB: Divide bytes by 4 to get the wchar_t count.  */
+	sarq	$2, %rdi
 #  endif
+	leaq	(CHAR_PER_VEC * 2)(%rdi, %rax), %rax
 	ret
 
 	.p2align 4
-L(first_vec_x3_check):
+L(last_vec_x3):
 	tzcntl	%eax, %eax
-#  ifdef USE_AS_WCSLEN
-	/* NB: Multiply wchar_t count by 4 to get the number of bytes.  */
-	sall	$2, %eax
-#  endif
+	subl	$(CHAR_PER_VEC * 2), %esi
 	/* Check the end of data.  */
-	cmpq	%rax, %rsi
-	jbe	L(max)
-	addq	$(VEC_SIZE * 3), %rax
-	addq	%rdi, %rax
-	subq	%rdx, %rax
+	cmpl	%eax, %esi
+	jb	L(max_end)
+	subq	%rdx, %rdi
 #  ifdef USE_AS_WCSLEN
-	shrq	$2, %rax
+	/* NB: Divide bytes by 4 to get the wchar_t count.  */
+	sarq	$2, %rdi
 #  endif
+	leaq	(CHAR_PER_VEC * 3)(%rdi, %rax), %rax
 	ret
-
-	.p2align 4
-L(max):
+L(max_end):
 	movq	%r8, %rax
-#  ifdef USE_AS_WCSLEN
-	shrq	$2, %rax
-#  endif
-	ret
-
-	.p2align 4
-L(zero):
-	xorl	%eax, %eax
 	ret
 # endif
 
+	/* Cold case for crossing page with first load.	 */
 	.p2align 4
-L(first_vec_x0):
-	tzcntl	%eax, %eax
-# ifdef USE_AS_WCSLEN
-	/* NB: Multiply wchar_t count by 4 to get the number of bytes.  */
-	sall	$2, %eax
-# endif
-	addq	%rdi, %rax
-	subq	%rdx, %rax
+L(cross_page_boundary):
+	movq	%rdi, %rdx
+	/* Align data to VEC_SIZE.  */
+	andq	$-VEC_SIZE, %rdi
+	VPCMP	$0, (%rdi), %YMMZERO, %k0
+	kmovd	%k0, %eax
+	/* Remove the leading bytes.  */
 # ifdef USE_AS_WCSLEN
-	shrq	$2, %rax
+	/* NB: Divide shift count by 4 since each bit in K0 represent 4
+	   bytes.  */
+	movl	%edx, %ecx
+	shrl	$2, %ecx
+	andl	$(CHAR_PER_VEC - 1), %ecx
 # endif
-	ret
-
-	.p2align 4
-L(first_vec_x1):
+	/* SHIFT_REG is ecx for USE_AS_WCSLEN and edx otherwise.  */
+	sarxl	%SHIFT_REG, %eax, %eax
+	testl	%eax, %eax
+# ifndef USE_AS_STRNLEN
+	jz	L(cross_page_continue)
 	tzcntl	%eax, %eax
-# ifdef USE_AS_WCSLEN
-	/* NB: Multiply wchar_t count by 4 to get the number of bytes.  */
-	sall	$2, %eax
-# endif
-	addq	$VEC_SIZE, %rax
-	addq	%rdi, %rax
-	subq	%rdx, %rax
-# ifdef USE_AS_WCSLEN
-	shrq	$2, %rax
-# endif
 	ret
-
-	.p2align 4
-L(first_vec_x2):
-	tzcntl	%eax, %eax
-# ifdef USE_AS_WCSLEN
-	/* NB: Multiply wchar_t count by 4 to get the number of bytes.  */
-	sall	$2, %eax
-# endif
-	addq	$(VEC_SIZE * 2), %rax
-	addq	%rdi, %rax
-	subq	%rdx, %rax
-# ifdef USE_AS_WCSLEN
-	shrq	$2, %rax
-# endif
+# else
+	jnz	L(cross_page_less_vec)
+#  ifndef USE_AS_WCSLEN
+	movl	%edx, %ecx
+	andl	$(CHAR_PER_VEC - 1), %ecx
+#  endif
+	movl	$CHAR_PER_VEC, %eax
+	subl	%ecx, %eax
+	/* Check the end of data.  */
+	cmpq	%rax, %rsi
+	ja	L(cross_page_continue)
+	movl	%esi, %eax
 	ret
-
-	.p2align 4
-L(4x_vec_end):
-	VPCMP	$0, %YMM1, %YMMZERO, %k0
-	kmovd	%k0, %eax
-	testl	%eax, %eax
-	jnz	L(first_vec_x0)
-	VPCMP	$0, %YMM2, %YMMZERO, %k1
-	kmovd	%k1, %eax
-	testl	%eax, %eax
-	jnz	L(first_vec_x1)
-	VPCMP	$0, %YMM3, %YMMZERO, %k2
-	kmovd	%k2, %eax
-	testl	%eax, %eax
-	jnz	L(first_vec_x2)
-	VPCMP	$0, %YMM4, %YMMZERO, %k3
-	kmovd	%k3, %eax
-L(first_vec_x3):
+L(cross_page_less_vec):
 	tzcntl	%eax, %eax
-# ifdef USE_AS_WCSLEN
-	/* NB: Multiply wchar_t count by 4 to get the number of bytes.  */
-	sall	$2, %eax
-# endif
-	addq	$(VEC_SIZE * 3), %rax
-	addq	%rdi, %rax
-	subq	%rdx, %rax
-# ifdef USE_AS_WCSLEN
-	shrq	$2, %rax
-# endif
+	/* Select min of length and position of first null.  */
+	cmpq	%rax, %rsi
+	cmovb	%esi, %eax
 	ret
+# endif
 
 END (STRLEN)
 #endif
diff --git a/sysdeps/x86_64/multiarch/strncmp-avx2-rtm.S b/sysdeps/x86_64/multiarch/strncmp-avx2-rtm.S
index 37d1224bb9..68bad365ba 100644
--- a/sysdeps/x86_64/multiarch/strncmp-avx2-rtm.S
+++ b/sysdeps/x86_64/multiarch/strncmp-avx2-rtm.S
@@ -1,3 +1,4 @@
 #define STRCMP	__strncmp_avx2_rtm
 #define USE_AS_STRNCMP 1
+#define OVERFLOW_STRCMP	__strcmp_avx2_rtm
 #include "strcmp-avx2-rtm.S"
diff --git a/sysdeps/x86_64/multiarch/strncmp-avx2.S b/sysdeps/x86_64/multiarch/strncmp-avx2.S
index 1678bcc235..f138e9f1fd 100644
--- a/sysdeps/x86_64/multiarch/strncmp-avx2.S
+++ b/sysdeps/x86_64/multiarch/strncmp-avx2.S
@@ -1,3 +1,4 @@
 #define STRCMP	__strncmp_avx2
 #define USE_AS_STRNCMP 1
+#define OVERFLOW_STRCMP __strcmp_avx2
 #include "strcmp-avx2.S"
diff --git a/sysdeps/x86_64/multiarch/wcsncmp-avx2-rtm.S b/sysdeps/x86_64/multiarch/wcsncmp-avx2-rtm.S
index 4e88c70cc6..f467582cbe 100644
--- a/sysdeps/x86_64/multiarch/wcsncmp-avx2-rtm.S
+++ b/sysdeps/x86_64/multiarch/wcsncmp-avx2-rtm.S
@@ -1,5 +1,5 @@
 #define STRCMP __wcsncmp_avx2_rtm
 #define USE_AS_STRNCMP 1
 #define USE_AS_WCSCMP 1
-
+#define OVERFLOW_STRCMP	__wcscmp_avx2_rtm
 #include "strcmp-avx2-rtm.S"
diff --git a/sysdeps/x86_64/multiarch/wcsncmp-avx2.S b/sysdeps/x86_64/multiarch/wcsncmp-avx2.S
index 4fa1de4d3f..e9ede522b8 100644
--- a/sysdeps/x86_64/multiarch/wcsncmp-avx2.S
+++ b/sysdeps/x86_64/multiarch/wcsncmp-avx2.S
@@ -1,5 +1,5 @@
 #define STRCMP __wcsncmp_avx2
 #define USE_AS_STRNCMP 1
 #define USE_AS_WCSCMP 1
-
+#define OVERFLOW_STRCMP	__wcscmp_avx2
 #include "strcmp-avx2.S"
diff --git a/sysdeps/x86_64/tst-rsi-strlen.c b/sysdeps/x86_64/tst-rsi-strlen.c
new file mode 100644
index 0000000000..a80c4f85c2
--- /dev/null
+++ b/sysdeps/x86_64/tst-rsi-strlen.c
@@ -0,0 +1,81 @@
+/* Test strlen with 0 in the RSI register.
+   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/>.  */
+
+#ifdef WIDE
+# define TEST_NAME "wcslen"
+#else
+# define TEST_NAME "strlen"
+#endif /* WIDE */
+
+#define TEST_MAIN
+#include <string/test-string.h>
+
+#ifdef WIDE
+# include <wchar.h>
+# define STRLEN wcslen
+# define CHAR wchar_t
+#else
+# define STRLEN strlen
+# define CHAR char
+#endif /* WIDE */
+
+IMPL (STRLEN, 1)
+
+typedef size_t (*proto_t) (const CHAR *);
+
+typedef struct
+{
+  void (*fn) (void);
+} parameter_t;
+
+size_t
+__attribute__ ((weak, noinline, noclone))
+do_strlen (parameter_t *a, int zero, const CHAR *str)
+{
+  return CALL (a, str);
+}
+
+static int
+test_main (void)
+{
+  test_init ();
+
+  size_t size = page_size / sizeof (CHAR) - 1;
+  CHAR *buf = (CHAR *) buf2;
+  buf[size] = 0;
+
+  parameter_t a;
+
+  int ret = 0;
+  FOR_EACH_IMPL (impl, 0)
+    {
+      a.fn = impl->fn;
+      /* NB: Pass 0 in RSI.  */
+      size_t res = do_strlen (&a, 0, buf);
+      if (res != size)
+	{
+	  error (0, 0, "Wrong result in function %s: %zu != %zu",
+		 impl->name, res, size);
+	  ret = 1;
+	}
+    }
+
+  return ret ? EXIT_FAILURE : EXIT_SUCCESS;
+}
+
+#include <support/test-driver.c>
diff --git a/sysdeps/x86_64/tst-rsi-wcslen.c b/sysdeps/x86_64/tst-rsi-wcslen.c
new file mode 100644
index 0000000000..f45a7dfb51
--- /dev/null
+++ b/sysdeps/x86_64/tst-rsi-wcslen.c
@@ -0,0 +1,20 @@
+/* Test wcslen with 0 in the RSI register.
+   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/>.  */
+
+#define WIDE 1
+#include "tst-rsi-strlen.c"