1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * Normally compiler builtins are used, but sometimes the compiler calls out
4 * of line code. Based on asm-i386/string.h.
5 *
6 * This assembly file is re-written from memmove_64.c file.
7 *	- Copyright 2011 Fenghua Yu <fenghua.yu@intel.com>
8 */
9#include <linux/export.h>
10#include <linux/linkage.h>
11#include <asm/cpufeatures.h>
12#include <asm/alternative.h>
13
14#undef memmove
15
16.section .noinstr.text, "ax"
17
18/*
19 * Implement memmove(). This can handle overlap between src and dst.
20 *
21 * Input:
22 * rdi: dest
23 * rsi: src
24 * rdx: count
25 *
26 * Output:
27 * rax: dest
28 */
29SYM_FUNC_START(__memmove)
30
31	mov %rdi, %rax
32
33	/* Decide forward/backward copy mode */
34	cmp %rdi, %rsi
35	jge .Lmemmove_begin_forward
36	mov %rsi, %r8
37	add %rdx, %r8
38	cmp %rdi, %r8
39	jg 2f
40
41#define CHECK_LEN	cmp $0x20, %rdx; jb 1f
42#define MEMMOVE_BYTES	movq %rdx, %rcx; rep movsb; RET
43.Lmemmove_begin_forward:
44	ALTERNATIVE_2 __stringify(CHECK_LEN), \
45		      __stringify(CHECK_LEN; MEMMOVE_BYTES), X86_FEATURE_ERMS, \
46		      __stringify(MEMMOVE_BYTES), X86_FEATURE_FSRM
47
48	/*
49	 * movsq instruction have many startup latency
50	 * so we handle small size by general register.
51	 */
52	cmp  $680, %rdx
53	jb	3f
54	/*
55	 * movsq instruction is only good for aligned case.
56	 */
57
58	cmpb %dil, %sil
59	je 4f
603:
61	sub $0x20, %rdx
62	/*
63	 * We gobble 32 bytes forward in each loop.
64	 */
655:
66	sub $0x20, %rdx
67	movq 0*8(%rsi), %r11
68	movq 1*8(%rsi), %r10
69	movq 2*8(%rsi), %r9
70	movq 3*8(%rsi), %r8
71	leaq 4*8(%rsi), %rsi
72
73	movq %r11, 0*8(%rdi)
74	movq %r10, 1*8(%rdi)
75	movq %r9, 2*8(%rdi)
76	movq %r8, 3*8(%rdi)
77	leaq 4*8(%rdi), %rdi
78	jae 5b
79	addq $0x20, %rdx
80	jmp 1f
81	/*
82	 * Handle data forward by movsq.
83	 */
84	.p2align 4
854:
86	movq %rdx, %rcx
87	movq -8(%rsi, %rdx), %r11
88	lea -8(%rdi, %rdx), %r10
89	shrq $3, %rcx
90	rep movsq
91	movq %r11, (%r10)
92	jmp 13f
93.Lmemmove_end_forward:
94
95	/*
96	 * Handle data backward by movsq.
97	 */
98	.p2align 4
997:
100	movq %rdx, %rcx
101	movq (%rsi), %r11
102	movq %rdi, %r10
103	leaq -8(%rsi, %rdx), %rsi
104	leaq -8(%rdi, %rdx), %rdi
105	shrq $3, %rcx
106	std
107	rep movsq
108	cld
109	movq %r11, (%r10)
110	jmp 13f
111
112	/*
113	 * Start to prepare for backward copy.
114	 */
115	.p2align 4
1162:
117	cmp $0x20, %rdx
118	jb 1f
119	cmp $680, %rdx
120	jb 6f
121	cmp %dil, %sil
122	je 7b
1236:
124	/*
125	 * Calculate copy position to tail.
126	 */
127	addq %rdx, %rsi
128	addq %rdx, %rdi
129	subq $0x20, %rdx
130	/*
131	 * We gobble 32 bytes backward in each loop.
132	 */
1338:
134	subq $0x20, %rdx
135	movq -1*8(%rsi), %r11
136	movq -2*8(%rsi), %r10
137	movq -3*8(%rsi), %r9
138	movq -4*8(%rsi), %r8
139	leaq -4*8(%rsi), %rsi
140
141	movq %r11, -1*8(%rdi)
142	movq %r10, -2*8(%rdi)
143	movq %r9, -3*8(%rdi)
144	movq %r8, -4*8(%rdi)
145	leaq -4*8(%rdi), %rdi
146	jae 8b
147	/*
148	 * Calculate copy position to head.
149	 */
150	addq $0x20, %rdx
151	subq %rdx, %rsi
152	subq %rdx, %rdi
1531:
154	cmpq $16, %rdx
155	jb 9f
156	/*
157	 * Move data from 16 bytes to 31 bytes.
158	 */
159	movq 0*8(%rsi), %r11
160	movq 1*8(%rsi), %r10
161	movq -2*8(%rsi, %rdx), %r9
162	movq -1*8(%rsi, %rdx), %r8
163	movq %r11, 0*8(%rdi)
164	movq %r10, 1*8(%rdi)
165	movq %r9, -2*8(%rdi, %rdx)
166	movq %r8, -1*8(%rdi, %rdx)
167	jmp 13f
168	.p2align 4
1699:
170	cmpq $8, %rdx
171	jb 10f
172	/*
173	 * Move data from 8 bytes to 15 bytes.
174	 */
175	movq 0*8(%rsi), %r11
176	movq -1*8(%rsi, %rdx), %r10
177	movq %r11, 0*8(%rdi)
178	movq %r10, -1*8(%rdi, %rdx)
179	jmp 13f
18010:
181	cmpq $4, %rdx
182	jb 11f
183	/*
184	 * Move data from 4 bytes to 7 bytes.
185	 */
186	movl (%rsi), %r11d
187	movl -4(%rsi, %rdx), %r10d
188	movl %r11d, (%rdi)
189	movl %r10d, -4(%rdi, %rdx)
190	jmp 13f
19111:
192	cmp $2, %rdx
193	jb 12f
194	/*
195	 * Move data from 2 bytes to 3 bytes.
196	 */
197	movw (%rsi), %r11w
198	movw -2(%rsi, %rdx), %r10w
199	movw %r11w, (%rdi)
200	movw %r10w, -2(%rdi, %rdx)
201	jmp 13f
20212:
203	cmp $1, %rdx
204	jb 13f
205	/*
206	 * Move data for 1 byte.
207	 */
208	movb (%rsi), %r11b
209	movb %r11b, (%rdi)
21013:
211	RET
212SYM_FUNC_END(__memmove)
213EXPORT_SYMBOL(__memmove)
214
215SYM_FUNC_ALIAS_MEMFUNC(memmove, __memmove)
216EXPORT_SYMBOL(memmove)
217