intrinsics.c

 1// SPDX-License-Identifier: GPL-2.0
 2
 3#include <linux/efi.h>
 4#include <asm/efi.h>
 5#include <asm/string.h>
 6
 7#include "efistub.h"
 8
 9#ifdef CONFIG_KASAN
10#undef memcpy
11#undef memmove
12#undef memset
13void *__memcpy(void *__dest, const void *__src, size_t __n) __alias(memcpy);
14void *__memmove(void *__dest, const void *__src, size_t count) __alias(memmove);
15void *__memset(void *s, int c, size_t count) __alias(memset);
16#endif
17
18static void *efistub_memmove(u8 *dst, const u8 *src, size_t len)
19{
20	if (src > dst || dst >= (src + len))
21		for (size_t i = 0; i < len; i++)
22			dst[i] = src[i];
23	else
24		for (ssize_t i = len - 1; i >= 0; i--)
25			dst[i] = src[i];
26
27	return dst;
28}
29
30static void *efistub_memset(void *dst, int c, size_t len)
31{
32	for (u8 *d = dst; len--; d++)
33		*d = c;
34
35	return dst;
36}
37
38void *memcpy(void *dst, const void *src, size_t len)
39{
40	if (efi_table_attr(efi_system_table, boottime) == NULL)
41		return efistub_memmove(dst, src, len);
42
43	efi_bs_call(copy_mem, dst, src, len);
44	return dst;
45}
46
47extern void *memmove(void *dst, const void *src, size_t len) __alias(memcpy);
48
49void *memset(void *dst, int c, size_t len)
50{
51	if (efi_table_attr(efi_system_table, boottime) == NULL)
52		return efistub_memset(dst, c, len);
53
54	efi_bs_call(set_mem, dst, len, c & U8_MAX);
55	return dst;
56}
57
58/**
59 * memcmp - Compare two areas of memory
60 * @cs: One area of memory
61 * @ct: Another area of memory
62 * @count: The size of the area.
63 */
64#undef memcmp
65int memcmp(const void *cs, const void *ct, size_t count)
66{
67	const unsigned char *su1, *su2;
68	int res = 0;
69
70	for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
71		if ((res = *su1 - *su2) != 0)
72			break;
73	return res;
74}