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1/* SPDX-License-Identifier: GPL-2.0-only */
2/* Copyright 2002 Andi Kleen */
3
4#include <linux/export.h>
5#include <linux/linkage.h>
6#include <linux/cfi_types.h>
7#include <asm/errno.h>
8#include <asm/cpufeatures.h>
9#include <asm/alternative.h>
10
11.section .noinstr.text, "ax"
12
13/*
14 * memcpy - Copy a memory block.
15 *
16 * Input:
17 * rdi destination
18 * rsi source
19 * rdx count
20 *
21 * Output:
22 * rax original destination
23 *
24 * The FSRM alternative should be done inline (avoiding the call and
25 * the disgusting return handling), but that would require some help
26 * from the compiler for better calling conventions.
27 *
28 * The 'rep movsb' itself is small enough to replace the call, but the
29 * two register moves blow up the code. And one of them is "needed"
30 * only for the return value that is the same as the source input,
31 * which the compiler could/should do much better anyway.
32 */
33SYM_TYPED_FUNC_START(__memcpy)
34 ALTERNATIVE "jmp memcpy_orig", "", X86_FEATURE_FSRM
35
36 movq %rdi, %rax
37 movq %rdx, %rcx
38 rep movsb
39 RET
40SYM_FUNC_END(__memcpy)
41EXPORT_SYMBOL(__memcpy)
42
43SYM_FUNC_ALIAS_MEMFUNC(memcpy, __memcpy)
44EXPORT_SYMBOL(memcpy)
45
46SYM_FUNC_START_LOCAL(memcpy_orig)
47 movq %rdi, %rax
48
49 cmpq $0x20, %rdx
50 jb .Lhandle_tail
51
52 /*
53 * We check whether memory false dependence could occur,
54 * then jump to corresponding copy mode.
55 */
56 cmp %dil, %sil
57 jl .Lcopy_backward
58 subq $0x20, %rdx
59.Lcopy_forward_loop:
60 subq $0x20, %rdx
61
62 /*
63 * Move in blocks of 4x8 bytes:
64 */
65 movq 0*8(%rsi), %r8
66 movq 1*8(%rsi), %r9
67 movq 2*8(%rsi), %r10
68 movq 3*8(%rsi), %r11
69 leaq 4*8(%rsi), %rsi
70
71 movq %r8, 0*8(%rdi)
72 movq %r9, 1*8(%rdi)
73 movq %r10, 2*8(%rdi)
74 movq %r11, 3*8(%rdi)
75 leaq 4*8(%rdi), %rdi
76 jae .Lcopy_forward_loop
77 addl $0x20, %edx
78 jmp .Lhandle_tail
79
80.Lcopy_backward:
81 /*
82 * Calculate copy position to tail.
83 */
84 addq %rdx, %rsi
85 addq %rdx, %rdi
86 subq $0x20, %rdx
87 /*
88 * At most 3 ALU operations in one cycle,
89 * so append NOPS in the same 16 bytes trunk.
90 */
91 .p2align 4
92.Lcopy_backward_loop:
93 subq $0x20, %rdx
94 movq -1*8(%rsi), %r8
95 movq -2*8(%rsi), %r9
96 movq -3*8(%rsi), %r10
97 movq -4*8(%rsi), %r11
98 leaq -4*8(%rsi), %rsi
99 movq %r8, -1*8(%rdi)
100 movq %r9, -2*8(%rdi)
101 movq %r10, -3*8(%rdi)
102 movq %r11, -4*8(%rdi)
103 leaq -4*8(%rdi), %rdi
104 jae .Lcopy_backward_loop
105
106 /*
107 * Calculate copy position to head.
108 */
109 addl $0x20, %edx
110 subq %rdx, %rsi
111 subq %rdx, %rdi
112.Lhandle_tail:
113 cmpl $16, %edx
114 jb .Lless_16bytes
115
116 /*
117 * Move data from 16 bytes to 31 bytes.
118 */
119 movq 0*8(%rsi), %r8
120 movq 1*8(%rsi), %r9
121 movq -2*8(%rsi, %rdx), %r10
122 movq -1*8(%rsi, %rdx), %r11
123 movq %r8, 0*8(%rdi)
124 movq %r9, 1*8(%rdi)
125 movq %r10, -2*8(%rdi, %rdx)
126 movq %r11, -1*8(%rdi, %rdx)
127 RET
128 .p2align 4
129.Lless_16bytes:
130 cmpl $8, %edx
131 jb .Lless_8bytes
132 /*
133 * Move data from 8 bytes to 15 bytes.
134 */
135 movq 0*8(%rsi), %r8
136 movq -1*8(%rsi, %rdx), %r9
137 movq %r8, 0*8(%rdi)
138 movq %r9, -1*8(%rdi, %rdx)
139 RET
140 .p2align 4
141.Lless_8bytes:
142 cmpl $4, %edx
143 jb .Lless_3bytes
144
145 /*
146 * Move data from 4 bytes to 7 bytes.
147 */
148 movl (%rsi), %ecx
149 movl -4(%rsi, %rdx), %r8d
150 movl %ecx, (%rdi)
151 movl %r8d, -4(%rdi, %rdx)
152 RET
153 .p2align 4
154.Lless_3bytes:
155 subl $1, %edx
156 jb .Lend
157 /*
158 * Move data from 1 bytes to 3 bytes.
159 */
160 movzbl (%rsi), %ecx
161 jz .Lstore_1byte
162 movzbq 1(%rsi), %r8
163 movzbq (%rsi, %rdx), %r9
164 movb %r8b, 1(%rdi)
165 movb %r9b, (%rdi, %rdx)
166.Lstore_1byte:
167 movb %cl, (%rdi)
168
169.Lend:
170 RET
171SYM_FUNC_END(memcpy_orig)
172
1/* SPDX-License-Identifier: GPL-2.0-only */
2/* Copyright 2002 Andi Kleen */
3
4#include <linux/export.h>
5#include <linux/linkage.h>
6#include <linux/cfi_types.h>
7#include <asm/errno.h>
8#include <asm/cpufeatures.h>
9#include <asm/alternative.h>
10
11.section .noinstr.text, "ax"
12
13/*
14 * memcpy - Copy a memory block.
15 *
16 * Input:
17 * rdi destination
18 * rsi source
19 * rdx count
20 *
21 * Output:
22 * rax original destination
23 *
24 * The FSRM alternative should be done inline (avoiding the call and
25 * the disgusting return handling), but that would require some help
26 * from the compiler for better calling conventions.
27 *
28 * The 'rep movsb' itself is small enough to replace the call, but the
29 * two register moves blow up the code. And one of them is "needed"
30 * only for the return value that is the same as the source input,
31 * which the compiler could/should do much better anyway.
32 */
33SYM_TYPED_FUNC_START(__memcpy)
34 ALTERNATIVE "jmp memcpy_orig", "", X86_FEATURE_FSRM
35
36 movq %rdi, %rax
37 movq %rdx, %rcx
38 rep movsb
39 RET
40SYM_FUNC_END(__memcpy)
41EXPORT_SYMBOL(__memcpy)
42
43SYM_FUNC_ALIAS_MEMFUNC(memcpy, __memcpy)
44EXPORT_SYMBOL(memcpy)
45
46SYM_FUNC_START_LOCAL(memcpy_orig)
47 movq %rdi, %rax
48
49 cmpq $0x20, %rdx
50 jb .Lhandle_tail
51
52 /*
53 * We check whether memory false dependence could occur,
54 * then jump to corresponding copy mode.
55 */
56 cmp %dil, %sil
57 jl .Lcopy_backward
58 subq $0x20, %rdx
59.Lcopy_forward_loop:
60 subq $0x20, %rdx
61
62 /*
63 * Move in blocks of 4x8 bytes:
64 */
65 movq 0*8(%rsi), %r8
66 movq 1*8(%rsi), %r9
67 movq 2*8(%rsi), %r10
68 movq 3*8(%rsi), %r11
69 leaq 4*8(%rsi), %rsi
70
71 movq %r8, 0*8(%rdi)
72 movq %r9, 1*8(%rdi)
73 movq %r10, 2*8(%rdi)
74 movq %r11, 3*8(%rdi)
75 leaq 4*8(%rdi), %rdi
76 jae .Lcopy_forward_loop
77 addl $0x20, %edx
78 jmp .Lhandle_tail
79
80.Lcopy_backward:
81 /*
82 * Calculate copy position to tail.
83 */
84 addq %rdx, %rsi
85 addq %rdx, %rdi
86 subq $0x20, %rdx
87 /*
88 * At most 3 ALU operations in one cycle,
89 * so append NOPS in the same 16 bytes trunk.
90 */
91 .p2align 4
92.Lcopy_backward_loop:
93 subq $0x20, %rdx
94 movq -1*8(%rsi), %r8
95 movq -2*8(%rsi), %r9
96 movq -3*8(%rsi), %r10
97 movq -4*8(%rsi), %r11
98 leaq -4*8(%rsi), %rsi
99 movq %r8, -1*8(%rdi)
100 movq %r9, -2*8(%rdi)
101 movq %r10, -3*8(%rdi)
102 movq %r11, -4*8(%rdi)
103 leaq -4*8(%rdi), %rdi
104 jae .Lcopy_backward_loop
105
106 /*
107 * Calculate copy position to head.
108 */
109 addl $0x20, %edx
110 subq %rdx, %rsi
111 subq %rdx, %rdi
112.Lhandle_tail:
113 cmpl $16, %edx
114 jb .Lless_16bytes
115
116 /*
117 * Move data from 16 bytes to 31 bytes.
118 */
119 movq 0*8(%rsi), %r8
120 movq 1*8(%rsi), %r9
121 movq -2*8(%rsi, %rdx), %r10
122 movq -1*8(%rsi, %rdx), %r11
123 movq %r8, 0*8(%rdi)
124 movq %r9, 1*8(%rdi)
125 movq %r10, -2*8(%rdi, %rdx)
126 movq %r11, -1*8(%rdi, %rdx)
127 RET
128 .p2align 4
129.Lless_16bytes:
130 cmpl $8, %edx
131 jb .Lless_8bytes
132 /*
133 * Move data from 8 bytes to 15 bytes.
134 */
135 movq 0*8(%rsi), %r8
136 movq -1*8(%rsi, %rdx), %r9
137 movq %r8, 0*8(%rdi)
138 movq %r9, -1*8(%rdi, %rdx)
139 RET
140 .p2align 4
141.Lless_8bytes:
142 cmpl $4, %edx
143 jb .Lless_3bytes
144
145 /*
146 * Move data from 4 bytes to 7 bytes.
147 */
148 movl (%rsi), %ecx
149 movl -4(%rsi, %rdx), %r8d
150 movl %ecx, (%rdi)
151 movl %r8d, -4(%rdi, %rdx)
152 RET
153 .p2align 4
154.Lless_3bytes:
155 subl $1, %edx
156 jb .Lend
157 /*
158 * Move data from 1 bytes to 3 bytes.
159 */
160 movzbl (%rsi), %ecx
161 jz .Lstore_1byte
162 movzbq 1(%rsi), %r8
163 movzbq (%rsi, %rdx), %r9
164 movb %r8b, 1(%rdi)
165 movb %r9b, (%rdi, %rdx)
166.Lstore_1byte:
167 movb %cl, (%rdi)
168
169.Lend:
170 RET
171SYM_FUNC_END(memcpy_orig)
172