// SPDX-License-Identifier: GPL-2.0
/*
* Optimized string functions
*
* S390 version
* Copyright IBM Corp. 2004
* Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
*/
#define IN_ARCH_STRING_C 1
#ifndef __NO_FORTIFY
# define __NO_FORTIFY
#endif
#include <linux/types.h>
#include <linux/string.h>
#include <linux/export.h>
/*
* Helper functions to find the end of a string
*/
static inline char *__strend(const char *s)
{
unsigned long e = 0;
asm volatile(
" lghi 0,0\n"
"0: srst %[e],%[s]\n"
" jo 0b\n"
: [e] "+&a" (e), [s] "+&a" (s)
:
: "cc", "memory", "0");
return (char *)e;
}
static inline char *__strnend(const char *s, size_t n)
{
const char *p = s + n;
asm volatile(
" lghi 0,0\n"
"0: srst %[p],%[s]\n"
" jo 0b\n"
: [p] "+&d" (p), [s] "+&a" (s)
:
: "cc", "memory", "0");
return (char *)p;
}
/**
* strlen - Find the length of a string
* @s: The string to be sized
*
* returns the length of @s
*/
#ifdef __HAVE_ARCH_STRLEN
size_t strlen(const char *s)
{
return __strend(s) - s;
}
EXPORT_SYMBOL(strlen);
#endif
/**
* strnlen - Find the length of a length-limited string
* @s: The string to be sized
* @n: The maximum number of bytes to search
*
* returns the minimum of the length of @s and @n
*/
#ifdef __HAVE_ARCH_STRNLEN
size_t strnlen(const char *s, size_t n)
{
return __strnend(s, n) - s;
}
EXPORT_SYMBOL(strnlen);
#endif
/**
* strcpy - Copy a %NUL terminated string
* @dest: Where to copy the string to
* @src: Where to copy the string from
*
* returns a pointer to @dest
*/
#ifdef __HAVE_ARCH_STRCPY
char *strcpy(char *dest, const char *src)
{
char *ret = dest;
asm volatile(
" lghi 0,0\n"
"0: mvst %[dest],%[src]\n"
" jo 0b\n"
: [dest] "+&a" (dest), [src] "+&a" (src)
:
: "cc", "memory", "0");
return ret;
}
EXPORT_SYMBOL(strcpy);
#endif
/**
* strncpy - Copy a length-limited, %NUL-terminated string
* @dest: Where to copy the string to
* @src: Where to copy the string from
* @n: The maximum number of bytes to copy
*
* The result is not %NUL-terminated if the source exceeds
* @n bytes.
*/
#ifdef __HAVE_ARCH_STRNCPY
char *strncpy(char *dest, const char *src, size_t n)
{
size_t len = __strnend(src, n) - src;
memset(dest + len, 0, n - len);
memcpy(dest, src, len);
return dest;
}
EXPORT_SYMBOL(strncpy);
#endif
/**
* strcat - Append one %NUL-terminated string to another
* @dest: The string to be appended to
* @src: The string to append to it
*
* returns a pointer to @dest
*/
#ifdef __HAVE_ARCH_STRCAT
char *strcat(char *dest, const char *src)
{
unsigned long dummy = 0;
char *ret = dest;
asm volatile(
" lghi 0,0\n"
"0: srst %[dummy],%[dest]\n"
" jo 0b\n"
"1: mvst %[dummy],%[src]\n"
" jo 1b\n"
: [dummy] "+&a" (dummy), [dest] "+&a" (dest), [src] "+&a" (src)
:
: "cc", "memory", "0");
return ret;
}
EXPORT_SYMBOL(strcat);
#endif
/**
* strlcat - Append a length-limited, %NUL-terminated string to another
* @dest: The string to be appended to
* @src: The string to append to it
* @n: The size of the destination buffer.
*/
#ifdef __HAVE_ARCH_STRLCAT
size_t strlcat(char *dest, const char *src, size_t n)
{
size_t dsize = __strend(dest) - dest;
size_t len = __strend(src) - src;
size_t res = dsize + len;
if (dsize < n) {
dest += dsize;
n -= dsize;
if (len >= n)
len = n - 1;
dest[len] = '\0';
memcpy(dest, src, len);
}
return res;
}
EXPORT_SYMBOL(strlcat);
#endif
/**
* strncat - Append a length-limited, %NUL-terminated string to another
* @dest: The string to be appended to
* @src: The string to append to it
* @n: The maximum numbers of bytes to copy
*
* returns a pointer to @dest
*
* Note that in contrast to strncpy, strncat ensures the result is
* terminated.
*/
#ifdef __HAVE_ARCH_STRNCAT
char *strncat(char *dest, const char *src, size_t n)
{
size_t len = __strnend(src, n) - src;
char *p = __strend(dest);
p[len] = '\0';
memcpy(p, src, len);
return dest;
}
EXPORT_SYMBOL(strncat);
#endif
/**
* strcmp - Compare two strings
* @s1: One string
* @s2: Another string
*
* returns 0 if @s1 and @s2 are equal,
* < 0 if @s1 is less than @s2
* > 0 if @s1 is greater than @s2
*/
#ifdef __HAVE_ARCH_STRCMP
int strcmp(const char *s1, const char *s2)
{
int ret = 0;
asm volatile(
" lghi 0,0\n"
"0: clst %[s1],%[s2]\n"
" jo 0b\n"
" je 1f\n"
" ic %[ret],0(%[s1])\n"
" ic 0,0(%[s2])\n"
" sr %[ret],0\n"
"1:"
: [ret] "+&d" (ret), [s1] "+&a" (s1), [s2] "+&a" (s2)
:
: "cc", "memory", "0");
return ret;
}
EXPORT_SYMBOL(strcmp);
#endif
static inline int clcle(const char *s1, unsigned long l1,
const char *s2, unsigned long l2)
{
union register_pair r1 = { .even = (unsigned long)s1, .odd = l1, };
union register_pair r3 = { .even = (unsigned long)s2, .odd = l2, };
int cc;
asm volatile(
"0: clcle %[r1],%[r3],0\n"
" jo 0b\n"
" ipm %[cc]\n"
" srl %[cc],28\n"
: [cc] "=&d" (cc), [r1] "+&d" (r1.pair), [r3] "+&d" (r3.pair)
:
: "cc", "memory");
return cc;
}
/**
* strstr - Find the first substring in a %NUL terminated string
* @s1: The string to be searched
* @s2: The string to search for
*/
#ifdef __HAVE_ARCH_STRSTR
char *strstr(const char *s1, const char *s2)
{
int l1, l2;
l2 = __strend(s2) - s2;
if (!l2)
return (char *) s1;
l1 = __strend(s1) - s1;
while (l1-- >= l2) {
int cc;
cc = clcle(s1, l2, s2, l2);
if (!cc)
return (char *) s1;
s1++;
}
return NULL;
}
EXPORT_SYMBOL(strstr);
#endif
/**
* 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
*/
#ifdef __HAVE_ARCH_MEMCHR
void *memchr(const void *s, int c, size_t n)
{
const void *ret = s + n;
asm volatile(
" lgr 0,%[c]\n"
"0: srst %[ret],%[s]\n"
" jo 0b\n"
" jl 1f\n"
" la %[ret],0\n"
"1:"
: [ret] "+&a" (ret), [s] "+&a" (s)
: [c] "d" (c)
: "cc", "memory", "0");
return (void *) ret;
}
EXPORT_SYMBOL(memchr);
#endif
/**
* memcmp - Compare two areas of memory
* @s1: One area of memory
* @s2: Another area of memory
* @n: The size of the area.
*/
#ifdef __HAVE_ARCH_MEMCMP
int memcmp(const void *s1, const void *s2, size_t n)
{
int ret;
ret = clcle(s1, n, s2, n);
if (ret)
ret = ret == 1 ? -1 : 1;
return ret;
}
EXPORT_SYMBOL(memcmp);
#endif
/**
* memscan - 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 1 byte past
* the area if @c is not found
*/
#ifdef __HAVE_ARCH_MEMSCAN
void *memscan(void *s, int c, size_t n)
{
const void *ret = s + n;
asm volatile(
" lgr 0,%[c]\n"
"0: srst %[ret],%[s]\n"
" jo 0b\n"
: [ret] "+&a" (ret), [s] "+&a" (s)
: [c] "d" (c)
: "cc", "memory", "0");
return (void *)ret;
}
EXPORT_SYMBOL(memscan);
#endif