Adding upstream version 6.1.76.upstream/6.1.76upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 964 insertions, 0 deletions

diff --git a/lib/string.c b/lib/string.c
new file mode 100644
index 000000000..3371d26a0
--- /dev/null
+++ b/lib/string.c
@@ -0,0 +1,964 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  linux/lib/string.c
+ *
+ *  Copyright (C) 1991, 1992  Linus Torvalds
+ */
+
+/*
+ * This file should be used only for "library" routines that may have
+ * alternative implementations on specific architectures (generally
+ * found in <asm-xx/string.h>), or get overloaded by FORTIFY_SOURCE.
+ * (Specifically, this file is built with __NO_FORTIFY.)
+ *
+ * Other helper functions should live in string_helpers.c.
+ */
+
+#define __NO_FORTIFY
+#include <linux/types.h>
+#include <linux/string.h>
+#include <linux/ctype.h>
+#include <linux/kernel.h>
+#include <linux/export.h>
+#include <linux/bug.h>
+#include <linux/errno.h>
+#include <linux/slab.h>
+
+#include <asm/unaligned.h>
+#include <asm/byteorder.h>
+#include <asm/word-at-a-time.h>
+#include <asm/page.h>
+
+#ifndef __HAVE_ARCH_STRNCASECMP
+/**
+ * strncasecmp - Case insensitive, length-limited string comparison
+ * @s1: One string
+ * @s2: The other string
+ * @len: the maximum number of characters to compare
+ */
+int strncasecmp(const char *s1, const char *s2, size_t len)
+{
+	/* Yes, Virginia, it had better be unsigned */
+	unsigned char c1, c2;
+
+	if (!len)
+		return 0;
+
+	do {
+		c1 = *s1++;
+		c2 = *s2++;
+		if (!c1 || !c2)
+			break;
+		if (c1 == c2)
+			continue;
+		c1 = tolower(c1);
+		c2 = tolower(c2);
+		if (c1 != c2)
+			break;
+	} while (--len);
+	return (int)c1 - (int)c2;
+}
+EXPORT_SYMBOL(strncasecmp);
+#endif
+
+#ifndef __HAVE_ARCH_STRCASECMP
+int strcasecmp(const char *s1, const char *s2)
+{
+	int c1, c2;
+
+	do {
+		c1 = tolower(*s1++);
+		c2 = tolower(*s2++);
+	} while (c1 == c2 && c1 != 0);
+	return c1 - c2;
+}
+EXPORT_SYMBOL(strcasecmp);
+#endif
+
+#ifndef __HAVE_ARCH_STRCPY
+/**
+ * strcpy - Copy a %NUL terminated string
+ * @dest: Where to copy the string to
+ * @src: Where to copy the string from
+ */
+char *strcpy(char *dest, const char *src)
+{
+	char *tmp = dest;
+
+	while ((*dest++ = *src++) != '\0')
+		/* nothing */;
+	return tmp;
+}
+EXPORT_SYMBOL(strcpy);
+#endif
+
+#ifndef __HAVE_ARCH_STRNCPY
+/**
+ * strncpy - Copy a length-limited, C-string
+ * @dest: Where to copy the string to
+ * @src: Where to copy the string from
+ * @count: The maximum number of bytes to copy
+ *
+ * The result is not %NUL-terminated if the source exceeds
+ * @count bytes.
+ *
+ * In the case where the length of @src is less than  that  of
+ * count, the remainder of @dest will be padded with %NUL.
+ *
+ */
+char *strncpy(char *dest, const char *src, size_t count)
+{
+	char *tmp = dest;
+
+	while (count) {
+		if ((*tmp = *src) != 0)
+			src++;
+		tmp++;
+		count--;
+	}
+	return dest;
+}
+EXPORT_SYMBOL(strncpy);
+#endif
+
+#ifndef __HAVE_ARCH_STRLCPY
+/**
+ * strlcpy - Copy a C-string into a sized buffer
+ * @dest: Where to copy the string to
+ * @src: Where to copy the string from
+ * @size: size of destination buffer
+ *
+ * Compatible with ``*BSD``: the result is always a valid
+ * NUL-terminated string that fits in the buffer (unless,
+ * of course, the buffer size is zero). It does not pad
+ * out the result like strncpy() does.
+ */
+size_t strlcpy(char *dest, const char *src, size_t size)
+{
+	size_t ret = strlen(src);
+
+	if (size) {
+		size_t len = (ret >= size) ? size - 1 : ret;
+		memcpy(dest, src, len);
+		dest[len] = '\0';
+	}
+	return ret;
+}
+EXPORT_SYMBOL(strlcpy);
+#endif
+
+#ifndef __HAVE_ARCH_STRSCPY
+/**
+ * strscpy - Copy a C-string into a sized buffer
+ * @dest: Where to copy the string to
+ * @src: Where to copy the string from
+ * @count: Size of destination buffer
+ *
+ * Copy the string, or as much of it as fits, into the dest buffer.  The
+ * behavior is undefined if the string buffers overlap.  The destination
+ * buffer is always NUL terminated, unless it's zero-sized.
+ *
+ * Preferred to strlcpy() since the API doesn't require reading memory
+ * from the src string beyond the specified "count" bytes, and since
+ * the return value is easier to error-check than strlcpy()'s.
+ * In addition, the implementation is robust to the string changing out
+ * from underneath it, unlike the current strlcpy() implementation.
+ *
+ * Preferred to strncpy() since it always returns a valid string, and
+ * doesn't unnecessarily force the tail of the destination buffer to be
+ * zeroed.  If zeroing is desired please use strscpy_pad().
+ *
+ * Returns:
+ * * The number of characters copied (not including the trailing %NUL)
+ * * -E2BIG if count is 0 or @src was truncated.
+ */
+ssize_t strscpy(char *dest, const char *src, size_t count)
+{
+	const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS;
+	size_t max = count;
+	long res = 0;
+
+	if (count == 0 || WARN_ON_ONCE(count > INT_MAX))
+		return -E2BIG;
+
+#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
+	/*
+	 * If src is unaligned, don't cross a page boundary,
+	 * since we don't know if the next page is mapped.
+	 */
+	if ((long)src & (sizeof(long) - 1)) {
+		size_t limit = PAGE_SIZE - ((long)src & (PAGE_SIZE - 1));
+		if (limit < max)
+			max = limit;
+	}
+#else
+	/* If src or dest is unaligned, don't do word-at-a-time. */
+	if (((long) dest | (long) src) & (sizeof(long) - 1))
+		max = 0;
+#endif
+
+	/*
+	 * read_word_at_a_time() below may read uninitialized bytes after the
+	 * trailing zero and use them in comparisons. Disable this optimization
+	 * under KMSAN to prevent false positive reports.
+	 */
+	if (IS_ENABLED(CONFIG_KMSAN))
+		max = 0;
+
+	while (max >= sizeof(unsigned long)) {
+		unsigned long c, data;
+
+		c = read_word_at_a_time(src+res);
+		if (has_zero(c, &data, &constants)) {
+			data = prep_zero_mask(c, data, &constants);
+			data = create_zero_mask(data);
+			*(unsigned long *)(dest+res) = c & zero_bytemask(data);
+			return res + find_zero(data);
+		}
+		*(unsigned long *)(dest+res) = c;
+		res += sizeof(unsigned long);
+		count -= sizeof(unsigned long);
+		max -= sizeof(unsigned long);
+	}
+
+	while (count) {
+		char c;
+
+		c = src[res];
+		dest[res] = c;
+		if (!c)
+			return res;
+		res++;
+		count--;
+	}
+
+	/* Hit buffer length without finding a NUL; force NUL-termination. */
+	if (res)
+		dest[res-1] = '\0';
+
+	return -E2BIG;
+}
+EXPORT_SYMBOL(strscpy);
+#endif
+
+/**
+ * stpcpy - copy a string from src to dest returning a pointer to the new end
+ *          of dest, including src's %NUL-terminator. May overrun dest.
+ * @dest: pointer to end of string being copied into. Must be large enough
+ *        to receive copy.
+ * @src: pointer to the beginning of string being copied from. Must not overlap
+ *       dest.
+ *
+ * stpcpy differs from strcpy in a key way: the return value is a pointer
+ * to the new %NUL-terminating character in @dest. (For strcpy, the return
+ * value is a pointer to the start of @dest). This interface is considered
+ * unsafe as it doesn't perform bounds checking of the inputs. As such it's
+ * not recommended for usage. Instead, its definition is provided in case
+ * the compiler lowers other libcalls to stpcpy.
+ */
+char *stpcpy(char *__restrict__ dest, const char *__restrict__ src);
+char *stpcpy(char *__restrict__ dest, const char *__restrict__ src)
+{
+	while ((*dest++ = *src++) != '\0')
+		/* nothing */;
+	return --dest;
+}
+EXPORT_SYMBOL(stpcpy);
+
+#ifndef __HAVE_ARCH_STRCAT
+/**
+ * strcat - Append one %NUL-terminated string to another
+ * @dest: The string to be appended to
+ * @src: The string to append to it
+ */
+char *strcat(char *dest, const char *src)
+{
+	char *tmp = dest;
+
+	while (*dest)
+		dest++;
+	while ((*dest++ = *src++) != '\0')
+		;
+	return tmp;
+}
+EXPORT_SYMBOL(strcat);
+#endif
+
+#ifndef __HAVE_ARCH_STRNCAT
+/**
+ * strncat - Append a length-limited, C-string to another
+ * @dest: The string to be appended to
+ * @src: The string to append to it
+ * @count: The maximum numbers of bytes to copy
+ *
+ * Note that in contrast to strncpy(), strncat() ensures the result is
+ * terminated.
+ */
+char *strncat(char *dest, const char *src, size_t count)
+{
+	char *tmp = dest;
+
+	if (count) {
+		while (*dest)
+			dest++;
+		while ((*dest++ = *src++) != 0) {
+			if (--count == 0) {
+				*dest = '\0';
+				break;
+			}
+		}
+	}
+	return tmp;
+}
+EXPORT_SYMBOL(strncat);
+#endif
+
+#ifndef __HAVE_ARCH_STRLCAT
+/**
+ * strlcat - Append a length-limited, C-string to another
+ * @dest: The string to be appended to
+ * @src: The string to append to it
+ * @count: The size of the destination buffer.
+ */
+size_t strlcat(char *dest, const char *src, size_t count)
+{
+	size_t dsize = strlen(dest);
+	size_t len = strlen(src);
+	size_t res = dsize + len;
+
+	/* This would be a bug */
+	BUG_ON(dsize >= count);
+
+	dest += dsize;
+	count -= dsize;
+	if (len >= count)
+		len = count-1;
+	memcpy(dest, src, len);
+	dest[len] = 0;
+	return res;
+}
+EXPORT_SYMBOL(strlcat);
+#endif
+
+#ifndef __HAVE_ARCH_STRCMP
+/**
+ * strcmp - Compare two strings
+ * @cs: One string
+ * @ct: Another string
+ */
+int strcmp(const char *cs, const char *ct)
+{
+	unsigned char c1, c2;
+
+	while (1) {
+		c1 = *cs++;
+		c2 = *ct++;
+		if (c1 != c2)
+			return c1 < c2 ? -1 : 1;
+		if (!c1)
+			break;
+	}
+	return 0;
+}
+EXPORT_SYMBOL(strcmp);
+#endif
+
+#ifndef __HAVE_ARCH_STRNCMP
+/**
+ * strncmp - Compare two length-limited strings
+ * @cs: One string
+ * @ct: Another string
+ * @count: The maximum number of bytes to compare
+ */
+int strncmp(const char *cs, const char *ct, size_t count)
+{
+	unsigned char c1, c2;
+
+	while (count) {
+		c1 = *cs++;
+		c2 = *ct++;
+		if (c1 != c2)
+			return c1 < c2 ? -1 : 1;
+		if (!c1)
+			break;
+		count--;
+	}
+	return 0;
+}
+EXPORT_SYMBOL(strncmp);
+#endif
+
+#ifndef __HAVE_ARCH_STRCHR
+/**
+ * strchr - Find the first occurrence of a character in a string
+ * @s: The string to be searched
+ * @c: The character to search for
+ *
+ * Note that the %NUL-terminator is considered part of the string, and can
+ * be searched for.
+ */
+char *strchr(const char *s, int c)
+{
+	for (; *s != (char)c; ++s)
+		if (*s == '\0')
+			return NULL;
+	return (char *)s;
+}
+EXPORT_SYMBOL(strchr);
+#endif
+
+#ifndef __HAVE_ARCH_STRCHRNUL
+/**
+ * strchrnul - Find and return a character in a string, or end of string
+ * @s: The string to be searched
+ * @c: The character to search for
+ *
+ * Returns pointer to first occurrence of 'c' in s. If c is not found, then
+ * return a pointer to the null byte at the end of s.
+ */
+char *strchrnul(const char *s, int c)
+{
+	while (*s && *s != (char)c)
+		s++;
+	return (char *)s;
+}
+EXPORT_SYMBOL(strchrnul);
+#endif
+
+/**
+ * strnchrnul - Find and return a character in a length limited string,
+ * or end of string
+ * @s: The string to be searched
+ * @count: The number of characters to be searched
+ * @c: The character to search for
+ *
+ * Returns pointer to the first occurrence of 'c' in s. If c is not found,
+ * then return a pointer to the last character of the string.
+ */
+char *strnchrnul(const char *s, size_t count, int c)
+{
+	while (count-- && *s && *s != (char)c)
+		s++;
+	return (char *)s;
+}
+
+#ifndef __HAVE_ARCH_STRRCHR
+/**
+ * strrchr - Find the last occurrence of a character in a string
+ * @s: The string to be searched
+ * @c: The character to search for
+ */
+char *strrchr(const char *s, int c)
+{
+	const char *last = NULL;
+	do {
+		if (*s == (char)c)
+			last = s;
+	} while (*s++);
+	return (char *)last;
+}
+EXPORT_SYMBOL(strrchr);
+#endif
+
+#ifndef __HAVE_ARCH_STRNCHR
+/**
+ * strnchr - Find a character in a length limited string
+ * @s: The string to be searched
+ * @count: The number of characters to be searched
+ * @c: The character to search for
+ *
+ * Note that the %NUL-terminator is considered part of the string, and can
+ * be searched for.
+ */
+char *strnchr(const char *s, size_t count, int c)
+{
+	while (count--) {
+		if (*s == (char)c)
+			return (char *)s;
+		if (*s++ == '\0')
+			break;
+	}
+	return NULL;
+}
+EXPORT_SYMBOL(strnchr);
+#endif
+
+#ifndef __HAVE_ARCH_STRLEN
+/**
+ * strlen - Find the length of a string
+ * @s: The string to be sized
+ */
+size_t strlen(const char *s)
+{
+	const char *sc;
+
+	for (sc = s; *sc != '\0'; ++sc)
+		/* nothing */;
+	return sc - s;
+}
+EXPORT_SYMBOL(strlen);
+#endif
+
+#ifndef __HAVE_ARCH_STRNLEN
+/**
+ * strnlen - Find the length of a length-limited string
+ * @s: The string to be sized
+ * @count: The maximum number of bytes to search
+ */
+size_t strnlen(const char *s, size_t count)
+{
+	const char *sc;
+
+	for (sc = s; count-- && *sc != '\0'; ++sc)
+		/* nothing */;
+	return sc - s;
+}
+EXPORT_SYMBOL(strnlen);
+#endif
+
+#ifndef __HAVE_ARCH_STRSPN
+/**
+ * strspn - Calculate the length of the initial substring of @s which only contain letters in @accept
+ * @s: The string to be searched
+ * @accept: The string to search for
+ */
+size_t strspn(const char *s, const char *accept)
+{
+	const char *p;
+
+	for (p = s; *p != '\0'; ++p) {
+		if (!strchr(accept, *p))
+			break;
+	}
+	return p - s;
+}
+EXPORT_SYMBOL(strspn);
+#endif
+
+#ifndef __HAVE_ARCH_STRCSPN
+/**
+ * strcspn - Calculate the length of the initial substring of @s which does not contain letters in @reject
+ * @s: The string to be searched
+ * @reject: The string to avoid
+ */
+size_t strcspn(const char *s, const char *reject)
+{
+	const char *p;
+
+	for (p = s; *p != '\0'; ++p) {
+		if (strchr(reject, *p))
+			break;
+	}
+	return p - s;
+}
+EXPORT_SYMBOL(strcspn);
+#endif
+
+#ifndef __HAVE_ARCH_STRPBRK
+/**
+ * strpbrk - Find the first occurrence of a set of characters
+ * @cs: The string to be searched
+ * @ct: The characters to search for
+ */
+char *strpbrk(const char *cs, const char *ct)
+{
+	const char *sc1, *sc2;
+
+	for (sc1 = cs; *sc1 != '\0'; ++sc1) {
+		for (sc2 = ct; *sc2 != '\0'; ++sc2) {
+			if (*sc1 == *sc2)
+				return (char *)sc1;
+		}
+	}
+	return NULL;
+}
+EXPORT_SYMBOL(strpbrk);
+#endif
+
+#ifndef __HAVE_ARCH_STRSEP
+/**
+ * strsep - Split a string into tokens
+ * @s: The string to be searched
+ * @ct: The characters to search for
+ *
+ * strsep() updates @s to point after the token, ready for the next call.
+ *
+ * It returns empty tokens, too, behaving exactly like the libc function
+ * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
+ * Same semantics, slimmer shape. ;)
+ */
+char *strsep(char **s, const char *ct)
+{
+	char *sbegin = *s;
+	char *end;
+
+	if (sbegin == NULL)
+		return NULL;
+
+	end = strpbrk(sbegin, ct);
+	if (end)
+		*end++ = '\0';
+	*s = end;
+	return sbegin;
+}
+EXPORT_SYMBOL(strsep);
+#endif
+
+#ifndef __HAVE_ARCH_MEMSET
+/**
+ * memset - Fill a region of memory with the given value
+ * @s: Pointer to the start of the area.
+ * @c: The byte to fill the area with
+ * @count: The size of the area.
+ *
+ * Do not use memset() to access IO space, use memset_io() instead.
+ */
+void *memset(void *s, int c, size_t count)
+{
+	char *xs = s;
+
+	while (count--)
+		*xs++ = c;
+	return s;
+}
+EXPORT_SYMBOL(memset);
+#endif
+
+#ifndef __HAVE_ARCH_MEMSET16
+/**
+ * memset16() - Fill a memory area with a uint16_t
+ * @s: Pointer to the start of the area.
+ * @v: The value to fill the area with
+ * @count: The number of values to store
+ *
+ * Differs from memset() in that it fills with a uint16_t instead
+ * of a byte.  Remember that @count is the number of uint16_ts to
+ * store, not the number of bytes.
+ */
+void *memset16(uint16_t *s, uint16_t v, size_t count)
+{
+	uint16_t *xs = s;
+
+	while (count--)
+		*xs++ = v;
+	return s;
+}
+EXPORT_SYMBOL(memset16);
+#endif
+
+#ifndef __HAVE_ARCH_MEMSET32
+/**
+ * memset32() - Fill a memory area with a uint32_t
+ * @s: Pointer to the start of the area.
+ * @v: The value to fill the area with
+ * @count: The number of values to store
+ *
+ * Differs from memset() in that it fills with a uint32_t instead
+ * of a byte.  Remember that @count is the number of uint32_ts to
+ * store, not the number of bytes.
+ */
+void *memset32(uint32_t *s, uint32_t v, size_t count)
+{
+	uint32_t *xs = s;
+
+	while (count--)
+		*xs++ = v;
+	return s;
+}
+EXPORT_SYMBOL(memset32);
+#endif
+
+#ifndef __HAVE_ARCH_MEMSET64
+/**
+ * memset64() - Fill a memory area with a uint64_t
+ * @s: Pointer to the start of the area.
+ * @v: The value to fill the area with
+ * @count: The number of values to store
+ *
+ * Differs from memset() in that it fills with a uint64_t instead
+ * of a byte.  Remember that @count is the number of uint64_ts to
+ * store, not the number of bytes.
+ */
+void *memset64(uint64_t *s, uint64_t v, size_t count)
+{
+	uint64_t *xs = s;
+
+	while (count--)
+		*xs++ = v;
+	return s;
+}
+EXPORT_SYMBOL(memset64);
+#endif
+
+#ifndef __HAVE_ARCH_MEMCPY
+/**
+ * memcpy - Copy one area of memory to another
+ * @dest: Where to copy to
+ * @src: Where to copy from
+ * @count: The size of the area.
+ *
+ * You should not use this function to access IO space, use memcpy_toio()
+ * or memcpy_fromio() instead.
+ */
+void *memcpy(void *dest, const void *src, size_t count)
+{
+	char *tmp = dest;
+	const char *s = src;
+
+	while (count--)
+		*tmp++ = *s++;
+	return dest;
+}
+EXPORT_SYMBOL(memcpy);
+#endif
+
+#ifndef __HAVE_ARCH_MEMMOVE
+/**
+ * memmove - Copy one area of memory to another
+ * @dest: Where to copy to
+ * @src: Where to copy from
+ * @count: The size of the area.
+ *
+ * Unlike memcpy(), memmove() copes with overlapping areas.
+ */
+void *memmove(void *dest, const void *src, size_t count)
+{
+	char *tmp;
+	const char *s;
+
+	if (dest <= src) {
+		tmp = dest;
+		s = src;
+		while (count--)
+			*tmp++ = *s++;
+	} else {
+		tmp = dest;
+		tmp += count;
+		s = src;
+		s += count;
+		while (count--)
+			*--tmp = *--s;
+	}
+	return dest;
+}
+EXPORT_SYMBOL(memmove);
+#endif
+
+#ifndef __HAVE_ARCH_MEMCMP
+/**
+ * memcmp - Compare two areas of memory
+ * @cs: One area of memory
+ * @ct: Another area of memory
+ * @count: The size of the area.
+ */
+#undef memcmp
+__visible int memcmp(const void *cs, const void *ct, size_t count)
+{
+	const unsigned char *su1, *su2;
+	int res = 0;
+
+#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
+	if (count >= sizeof(unsigned long)) {
+		const unsigned long *u1 = cs;
+		const unsigned long *u2 = ct;
+		do {
+			if (get_unaligned(u1) != get_unaligned(u2))
+				break;
+			u1++;
+			u2++;
+			count -= sizeof(unsigned long);
+		} while (count >= sizeof(unsigned long));
+		cs = u1;
+		ct = u2;
+	}
+#endif
+	for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
+		if ((res = *su1 - *su2) != 0)
+			break;
+	return res;
+}
+EXPORT_SYMBOL(memcmp);
+#endif
+
+#ifndef __HAVE_ARCH_BCMP
+/**
+ * bcmp - returns 0 if and only if the buffers have identical contents.
+ * @a: pointer to first buffer.
+ * @b: pointer to second buffer.
+ * @len: size of buffers.
+ *
+ * The sign or magnitude of a non-zero return value has no particular
+ * meaning, and architectures may implement their own more efficient bcmp(). So
+ * while this particular implementation is a simple (tail) call to memcmp, do
+ * not rely on anything but whether the return value is zero or non-zero.
+ */
+int bcmp(const void *a, const void *b, size_t len)
+{
+	return memcmp(a, b, len);
+}
+EXPORT_SYMBOL(bcmp);
+#endif
+
+#ifndef __HAVE_ARCH_MEMSCAN
+/**
+ * memscan - Find a character in an area of memory.
+ * @addr: The memory area
+ * @c: The byte to search for
+ * @size: The size of the area.
+ *
+ * returns the address of the first occurrence of @c, or 1 byte past
+ * the area if @c is not found
+ */
+void *memscan(void *addr, int c, size_t size)
+{
+	unsigned char *p = addr;
+
+	while (size) {
+		if (*p == (unsigned char)c)
+			return (void *)p;
+		p++;
+		size--;
+	}
+  	return (void *)p;
+}
+EXPORT_SYMBOL(memscan);
+#endif
+
+#ifndef __HAVE_ARCH_STRSTR
+/**
+ * strstr - Find the first substring in a %NUL terminated string
+ * @s1: The string to be searched
+ * @s2: The string to search for
+ */
+char *strstr(const char *s1, const char *s2)
+{
+	size_t l1, l2;
+
+	l2 = strlen(s2);
+	if (!l2)
+		return (char *)s1;
+	l1 = strlen(s1);
+	while (l1 >= l2) {
+		l1--;
+		if (!memcmp(s1, s2, l2))
+			return (char *)s1;
+		s1++;
+	}
+	return NULL;
+}
+EXPORT_SYMBOL(strstr);
+#endif
+
+#ifndef __HAVE_ARCH_STRNSTR
+/**
+ * strnstr - Find the first substring in a length-limited string
+ * @s1: The string to be searched
+ * @s2: The string to search for
+ * @len: the maximum number of characters to search
+ */
+char *strnstr(const char *s1, const char *s2, size_t len)
+{
+	size_t l2;
+
+	l2 = strlen(s2);
+	if (!l2)
+		return (char *)s1;
+	while (len >= l2) {
+		len--;
+		if (!memcmp(s1, s2, l2))
+			return (char *)s1;
+		s1++;
+	}
+	return NULL;
+}
+EXPORT_SYMBOL(strnstr);
+#endif
+
+#ifndef __HAVE_ARCH_MEMCHR
+/**
+ * memchr - Find a character in an area of memory.
+ * @s: The memory area
+ * @c: The byte to search for
+ * @n: The size of the area.
+ *
+ * returns the address of the first occurrence of @c, or %NULL
+ * if @c is not found
+ */
+void *memchr(const void *s, int c, size_t n)
+{
+	const unsigned char *p = s;
+	while (n-- != 0) {
+        	if ((unsigned char)c == *p++) {
+			return (void *)(p - 1);
+		}
+	}
+	return NULL;
+}
+EXPORT_SYMBOL(memchr);
+#endif
+
+static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes)
+{
+	while (bytes) {
+		if (*start != value)
+			return (void *)start;
+		start++;
+		bytes--;
+	}
+	return NULL;
+}
+
+/**
+ * memchr_inv - Find an unmatching character in an area of memory.
+ * @start: The memory area
+ * @c: Find a character other than c
+ * @bytes: The size of the area.
+ *
+ * returns the address of the first character other than @c, or %NULL
+ * if the whole buffer contains just @c.
+ */
+void *memchr_inv(const void *start, int c, size_t bytes)
+{
+	u8 value = c;
+	u64 value64;
+	unsigned int words, prefix;
+
+	if (bytes <= 16)
+		return check_bytes8(start, value, bytes);
+
+	value64 = value;
+#if defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER) && BITS_PER_LONG == 64
+	value64 *= 0x0101010101010101ULL;
+#elif defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER)
+	value64 *= 0x01010101;
+	value64 |= value64 << 32;
+#else
+	value64 |= value64 << 8;
+	value64 |= value64 << 16;
+	value64 |= value64 << 32;
+#endif
+
+	prefix = (unsigned long)start % 8;
+	if (prefix) {
+		u8 *r;
+
+		prefix = 8 - prefix;
+		r = check_bytes8(start, value, prefix);
+		if (r)
+			return r;
+		start += prefix;
+		bytes -= prefix;
+	}
+
+	words = bytes / 8;
+
+	while (words) {
+		if (*(u64 *)start != value64)
+			return check_bytes8(start, value, 8);
+		start += 8;
+		words--;
+	}
+
+	return check_bytes8(start, value, bytes % 8);
+}
+EXPORT_SYMBOL(memchr_inv);