1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0
2*4882a593Smuzhiyun /*
3*4882a593Smuzhiyun * This provides an optimized implementation of memcpy, and a simplified
4*4882a593Smuzhiyun * implementation of memset and memmove. These are used here because the
5*4882a593Smuzhiyun * standard kernel runtime versions are not yet available and we don't
6*4882a593Smuzhiyun * trust the gcc built-in implementations as they may do unexpected things
7*4882a593Smuzhiyun * (e.g. FPU ops) in the minimal decompression stub execution environment.
8*4882a593Smuzhiyun */
9*4882a593Smuzhiyun #include "error.h"
10*4882a593Smuzhiyun
11*4882a593Smuzhiyun #include "../string.c"
12*4882a593Smuzhiyun
13*4882a593Smuzhiyun #ifdef CONFIG_X86_32
____memcpy(void * dest,const void * src,size_t n)14*4882a593Smuzhiyun static void *____memcpy(void *dest, const void *src, size_t n)
15*4882a593Smuzhiyun {
16*4882a593Smuzhiyun int d0, d1, d2;
17*4882a593Smuzhiyun asm volatile(
18*4882a593Smuzhiyun "rep ; movsl\n\t"
19*4882a593Smuzhiyun "movl %4,%%ecx\n\t"
20*4882a593Smuzhiyun "rep ; movsb\n\t"
21*4882a593Smuzhiyun : "=&c" (d0), "=&D" (d1), "=&S" (d2)
22*4882a593Smuzhiyun : "0" (n >> 2), "g" (n & 3), "1" (dest), "2" (src)
23*4882a593Smuzhiyun : "memory");
24*4882a593Smuzhiyun
25*4882a593Smuzhiyun return dest;
26*4882a593Smuzhiyun }
27*4882a593Smuzhiyun #else
____memcpy(void * dest,const void * src,size_t n)28*4882a593Smuzhiyun static void *____memcpy(void *dest, const void *src, size_t n)
29*4882a593Smuzhiyun {
30*4882a593Smuzhiyun long d0, d1, d2;
31*4882a593Smuzhiyun asm volatile(
32*4882a593Smuzhiyun "rep ; movsq\n\t"
33*4882a593Smuzhiyun "movq %4,%%rcx\n\t"
34*4882a593Smuzhiyun "rep ; movsb\n\t"
35*4882a593Smuzhiyun : "=&c" (d0), "=&D" (d1), "=&S" (d2)
36*4882a593Smuzhiyun : "0" (n >> 3), "g" (n & 7), "1" (dest), "2" (src)
37*4882a593Smuzhiyun : "memory");
38*4882a593Smuzhiyun
39*4882a593Smuzhiyun return dest;
40*4882a593Smuzhiyun }
41*4882a593Smuzhiyun #endif
42*4882a593Smuzhiyun
memset(void * s,int c,size_t n)43*4882a593Smuzhiyun void *memset(void *s, int c, size_t n)
44*4882a593Smuzhiyun {
45*4882a593Smuzhiyun int i;
46*4882a593Smuzhiyun char *ss = s;
47*4882a593Smuzhiyun
48*4882a593Smuzhiyun for (i = 0; i < n; i++)
49*4882a593Smuzhiyun ss[i] = c;
50*4882a593Smuzhiyun return s;
51*4882a593Smuzhiyun }
52*4882a593Smuzhiyun
memmove(void * dest,const void * src,size_t n)53*4882a593Smuzhiyun void *memmove(void *dest, const void *src, size_t n)
54*4882a593Smuzhiyun {
55*4882a593Smuzhiyun unsigned char *d = dest;
56*4882a593Smuzhiyun const unsigned char *s = src;
57*4882a593Smuzhiyun
58*4882a593Smuzhiyun if (d <= s || d - s >= n)
59*4882a593Smuzhiyun return ____memcpy(dest, src, n);
60*4882a593Smuzhiyun
61*4882a593Smuzhiyun while (n-- > 0)
62*4882a593Smuzhiyun d[n] = s[n];
63*4882a593Smuzhiyun
64*4882a593Smuzhiyun return dest;
65*4882a593Smuzhiyun }
66*4882a593Smuzhiyun
67*4882a593Smuzhiyun /* Detect and warn about potential overlaps, but handle them with memmove. */
memcpy(void * dest,const void * src,size_t n)68*4882a593Smuzhiyun void *memcpy(void *dest, const void *src, size_t n)
69*4882a593Smuzhiyun {
70*4882a593Smuzhiyun if (dest > src && dest - src < n) {
71*4882a593Smuzhiyun warn("Avoiding potentially unsafe overlapping memcpy()!");
72*4882a593Smuzhiyun return memmove(dest, src, n);
73*4882a593Smuzhiyun }
74*4882a593Smuzhiyun return ____memcpy(dest, src, n);
75*4882a593Smuzhiyun }
76*4882a593Smuzhiyun
77*4882a593Smuzhiyun #ifdef CONFIG_KASAN
78*4882a593Smuzhiyun extern void *__memset(void *s, int c, size_t n) __alias(memset);
79*4882a593Smuzhiyun extern void *__memmove(void *dest, const void *src, size_t n) __alias(memmove);
80*4882a593Smuzhiyun extern void *__memcpy(void *dest, const void *src, size_t n) __alias(memcpy);
81*4882a593Smuzhiyun #endif
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