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// SPDX-License-Identifier: GPL-2.0
/*
* This provides an optimized implementation of memcpy, and a simplified
* implementation of memset and memmove. These are used here because the
* standard kernel runtime versions are not yet available and we don't
* trust the gcc built-in implementations as they may do unexpected things
* (e.g. FPU ops) in the minimal decompression stub execution environment.
*/
#include "error.h"
#include "../string.c"
#ifdef CONFIG_X86_32
static void *____memcpy(void *dest, const void *src, size_t n)
{
int d0, d1, d2;
asm volatile(
"rep ; movsl\n\t"
"movl %4,%%ecx\n\t"
"rep ; movsb\n\t"
: "=&c" (d0), "=&D" (d1), "=&S" (d2)
: "0" (n >> 2), "g" (n & 3), "1" (dest), "2" (src)
: "memory");
return dest;
}
#else
static void *____memcpy(void *dest, const void *src, size_t n)
{
long d0, d1, d2;
asm volatile(
"rep ; movsq\n\t"
"movq %4,%%rcx\n\t"
"rep ; movsb\n\t"
: "=&c" (d0), "=&D" (d1), "=&S" (d2)
: "0" (n >> 3), "g" (n & 7), "1" (dest), "2" (src)
: "memory");
return dest;
}
#endif
void *memset(void *s, int c, size_t n)
{
int i;
char *ss = s;
for (i = 0; i < n; i++)
ss[i] = c;
return s;
}
void *memmove(void *dest, const void *src, size_t n)
{
unsigned char *d = dest;
const unsigned char *s = src;
if (d <= s || d - s >= n)
return ____memcpy(dest, src, n);
while (n-- > 0)
d[n] = s[n];
return dest;
}
/* Detect and warn about potential overlaps, but handle them with memmove. */
void *memcpy(void *dest, const void *src, size_t n)
{
if (dest > src && dest - src < n) {
warn("Avoiding potentially unsafe overlapping memcpy()!");
return memmove(dest, src, n);
}
return ____memcpy(dest, src, n);
}
#ifdef CONFIG_KASAN
extern void *__memset(void *s, int c, size_t n) __alias(memset);
extern void *__memmove(void *dest, const void *src, size_t n) __alias(memmove);
extern void *__memcpy(void *dest, const void *src, size_t n) __alias(memcpy);
#endif
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