aboutsummaryrefslogtreecommitdiff
path: root/arch/x86/lib/memmove_64.c
blob: 6d0f0ec41b348ad2a912fdb184303c094ce1a996 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
/* Normally compiler builtins are used, but sometimes the compiler calls out
   of line code. Based on asm-i386/string.h.
 */
#define _STRING_C
#include <linux/string.h>
#include <linux/module.h>

#undef memmove
void *memmove(void *dest, const void *src, size_t count)
{
	unsigned long d0,d1,d2,d3,d4,d5,d6,d7;
	char *ret;

	__asm__ __volatile__(
		/* Handle more 32bytes in loop */
		"mov %2, %3\n\t"
		"cmp $0x20, %0\n\t"
		"jb	1f\n\t"

		/* Decide forward/backward copy mode */
		"cmp %2, %1\n\t"
		"jb	2f\n\t"

		/*
		 * movsq instruction have many startup latency
		 * so we handle small size by general register.
		 */
		"cmp  $680, %0\n\t"
		"jb 3f\n\t"
		/*
		 * movsq instruction is only good for aligned case.
		 */
		"cmpb %%dil, %%sil\n\t"
		"je 4f\n\t"
		"3:\n\t"
		"sub $0x20, %0\n\t"
		/*
		 * We gobble 32byts forward in each loop.
		 */
		"5:\n\t"
		"sub $0x20, %0\n\t"
		"movq 0*8(%1), %4\n\t"
		"movq 1*8(%1), %5\n\t"
		"movq 2*8(%1), %6\n\t"
		"movq 3*8(%1), %7\n\t"
		"leaq 4*8(%1), %1\n\t"

		"movq %4, 0*8(%2)\n\t"
		"movq %5, 1*8(%2)\n\t"
		"movq %6, 2*8(%2)\n\t"
		"movq %7, 3*8(%2)\n\t"
		"leaq 4*8(%2), %2\n\t"
		"jae 5b\n\t"
		"addq $0x20, %0\n\t"
		"jmp 1f\n\t"
		/*
		 * Handle data forward by movsq.
		 */
		".p2align 4\n\t"
		"4:\n\t"
		"movq %0, %8\n\t"
		"movq -8(%1, %0), %4\n\t"
		"lea -8(%2, %0), %5\n\t"
		"shrq $3, %8\n\t"
		"rep movsq\n\t"
		"movq %4, (%5)\n\t"
		"jmp 13f\n\t"
		/*
		 * Handle data backward by movsq.
		 */
		".p2align 4\n\t"
		"7:\n\t"
		"movq %0, %8\n\t"
		"movq (%1), %4\n\t"
		"movq %2, %5\n\t"
		"leaq -8(%1, %0), %1\n\t"
		"leaq -8(%2, %0), %2\n\t"
		"shrq $3, %8\n\t"
		"std\n\t"
		"rep movsq\n\t"
		"cld\n\t"
		"movq %4, (%5)\n\t"
		"jmp 13f\n\t"

		/*
		 * Start to prepare for backward copy.
		 */
		".p2align 4\n\t"
		"2:\n\t"
		"cmp $680, %0\n\t"
		"jb 6f \n\t"
		"cmp %%dil, %%sil\n\t"
		"je 7b \n\t"
		"6:\n\t"
		/*
		 * Calculate copy position to tail.
		 */
		"addq %0, %1\n\t"
		"addq %0, %2\n\t"
		"subq $0x20, %0\n\t"
		/*
		 * We gobble 32byts backward in each loop.
		 */
		"8:\n\t"
		"subq $0x20, %0\n\t"
		"movq -1*8(%1), %4\n\t"
		"movq -2*8(%1), %5\n\t"
		"movq -3*8(%1), %6\n\t"
		"movq -4*8(%1), %7\n\t"
		"leaq -4*8(%1), %1\n\t"

		"movq %4, -1*8(%2)\n\t"
		"movq %5, -2*8(%2)\n\t"
		"movq %6, -3*8(%2)\n\t"
		"movq %7, -4*8(%2)\n\t"
		"leaq -4*8(%2), %2\n\t"
		"jae 8b\n\t"
		/*
		 * Calculate copy position to head.
		 */
		"addq $0x20, %0\n\t"
		"subq %0, %1\n\t"
		"subq %0, %2\n\t"
		"1:\n\t"
		"cmpq $16, %0\n\t"
		"jb 9f\n\t"
		/*
		 * Move data from 16 bytes to 31 bytes.
		 */
		"movq 0*8(%1), %4\n\t"
		"movq 1*8(%1), %5\n\t"
		"movq -2*8(%1, %0), %6\n\t"
		"movq -1*8(%1, %0), %7\n\t"
		"movq %4, 0*8(%2)\n\t"
		"movq %5, 1*8(%2)\n\t"
		"movq %6, -2*8(%2, %0)\n\t"
		"movq %7, -1*8(%2, %0)\n\t"
		"jmp 13f\n\t"
		".p2align 4\n\t"
		"9:\n\t"
		"cmpq $8, %0\n\t"
		"jb 10f\n\t"
		/*
		 * Move data from 8 bytes to 15 bytes.
		 */
		"movq 0*8(%1), %4\n\t"
		"movq -1*8(%1, %0), %5\n\t"
		"movq %4, 0*8(%2)\n\t"
		"movq %5, -1*8(%2, %0)\n\t"
		"jmp 13f\n\t"
		"10:\n\t"
		"cmpq $4, %0\n\t"
		"jb 11f\n\t"
		/*
		 * Move data from 4 bytes to 7 bytes.
		 */
		"movl (%1), %4d\n\t"
		"movl -4(%1, %0), %5d\n\t"
		"movl %4d, (%2)\n\t"
		"movl %5d, -4(%2, %0)\n\t"
		"jmp 13f\n\t"
		"11:\n\t"
		"cmp $2, %0\n\t"
		"jb 12f\n\t"
		/*
		 * Move data from 2 bytes to 3 bytes.
		 */
		"movw (%1), %4w\n\t"
		"movw -2(%1, %0), %5w\n\t"
		"movw %4w, (%2)\n\t"
		"movw %5w, -2(%2, %0)\n\t"
		"jmp 13f\n\t"
		"12:\n\t"
		"cmp $1, %0\n\t"
		"jb 13f\n\t"
		/*
		 * Move data for 1 byte.
		 */
		"movb (%1), %4b\n\t"
		"movb %4b, (%2)\n\t"
		"13:\n\t"
		: "=&d" (d0), "=&S" (d1), "=&D" (d2), "=&a" (ret) ,
		  "=r"(d3), "=r"(d4), "=r"(d5), "=r"(d6), "=&c" (d7)
		:"0" (count),
		 "1" (src),
		 "2" (dest)
		:"memory");

		return ret;

}
EXPORT_SYMBOL(memmove);