Commit | Line | Data |
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1da177e4 | 1 | /* Copyright 2002 Andi Kleen, SuSE Labs */ |
8d379dad | 2 | |
8d379dad | 3 | #include <linux/linkage.h> |
cd4d09ec | 4 | #include <asm/cpufeatures.h> |
2f19e06a | 5 | #include <asm/alternative-asm.h> |
784d5699 | 6 | #include <asm/export.h> |
8d379dad | 7 | |
84d95ad4 BP |
8 | .weak memset |
9 | ||
1da177e4 | 10 | /* |
2f19e06a FY |
11 | * ISO C memset - set a memory block to a byte value. This function uses fast |
12 | * string to get better performance than the original function. The code is | |
6a6256f9 | 13 | * simpler and shorter than the original function as well. |
84d95ad4 | 14 | * |
1da177e4 | 15 | * rdi destination |
84d95ad4 BP |
16 | * rsi value (char) |
17 | * rdx count (bytes) | |
18 | * | |
1da177e4 | 19 | * rax original destination |
84d95ad4 BP |
20 | */ |
21 | ENTRY(memset) | |
22 | ENTRY(__memset) | |
23 | /* | |
24 | * Some CPUs support enhanced REP MOVSB/STOSB feature. It is recommended | |
25 | * to use it when possible. If not available, use fast string instructions. | |
26 | * | |
27 | * Otherwise, use original memset function. | |
28 | */ | |
29 | ALTERNATIVE_2 "jmp memset_orig", "", X86_FEATURE_REP_GOOD, \ | |
30 | "jmp memset_erms", X86_FEATURE_ERMS | |
31 | ||
8d379dad | 32 | movq %rdi,%r9 |
5d7244e7 JB |
33 | movq %rdx,%rcx |
34 | andl $7,%edx | |
35 | shrq $3,%rcx | |
8d379dad JB |
36 | /* expand byte value */ |
37 | movzbl %sil,%esi | |
38 | movabs $0x0101010101010101,%rax | |
5d7244e7 | 39 | imulq %rsi,%rax |
8d379dad | 40 | rep stosq |
5d7244e7 | 41 | movl %edx,%ecx |
8d379dad JB |
42 | rep stosb |
43 | movq %r9,%rax | |
44 | ret | |
84d95ad4 BP |
45 | ENDPROC(memset) |
46 | ENDPROC(__memset) | |
784d5699 AV |
47 | EXPORT_SYMBOL(memset) |
48 | EXPORT_SYMBOL(__memset) | |
8d379dad | 49 | |
2f19e06a FY |
50 | /* |
51 | * ISO C memset - set a memory block to a byte value. This function uses | |
52 | * enhanced rep stosb to override the fast string function. | |
53 | * The code is simpler and shorter than the fast string function as well. | |
54 | * | |
55 | * rdi destination | |
56 | * rsi value (char) | |
57 | * rdx count (bytes) | |
58 | * | |
59 | * rax original destination | |
60 | */ | |
84d95ad4 | 61 | ENTRY(memset_erms) |
2f19e06a FY |
62 | movq %rdi,%r9 |
63 | movb %sil,%al | |
5d7244e7 | 64 | movq %rdx,%rcx |
2f19e06a FY |
65 | rep stosb |
66 | movq %r9,%rax | |
67 | ret | |
84d95ad4 | 68 | ENDPROC(memset_erms) |
393f203f | 69 | |
84d95ad4 | 70 | ENTRY(memset_orig) |
7bcd3f34 | 71 | movq %rdi,%r10 |
7bcd3f34 AK |
72 | |
73 | /* expand byte value */ | |
74 | movzbl %sil,%ecx | |
75 | movabs $0x0101010101010101,%rax | |
5d7244e7 | 76 | imulq %rcx,%rax |
7bcd3f34 AK |
77 | |
78 | /* align dst */ | |
79 | movl %edi,%r9d | |
80 | andl $7,%r9d | |
81 | jnz .Lbad_alignment | |
82 | .Lafter_bad_alignment: | |
83 | ||
5d7244e7 JB |
84 | movq %rdx,%rcx |
85 | shrq $6,%rcx | |
7bcd3f34 AK |
86 | jz .Lhandle_tail |
87 | ||
88 | .p2align 4 | |
89 | .Lloop_64: | |
5d7244e7 | 90 | decq %rcx |
7bcd3f34 AK |
91 | movq %rax,(%rdi) |
92 | movq %rax,8(%rdi) | |
93 | movq %rax,16(%rdi) | |
94 | movq %rax,24(%rdi) | |
95 | movq %rax,32(%rdi) | |
96 | movq %rax,40(%rdi) | |
97 | movq %rax,48(%rdi) | |
98 | movq %rax,56(%rdi) | |
99 | leaq 64(%rdi),%rdi | |
100 | jnz .Lloop_64 | |
101 | ||
102 | /* Handle tail in loops. The loops should be faster than hard | |
103 | to predict jump tables. */ | |
104 | .p2align 4 | |
105 | .Lhandle_tail: | |
5d7244e7 | 106 | movl %edx,%ecx |
7bcd3f34 AK |
107 | andl $63&(~7),%ecx |
108 | jz .Lhandle_7 | |
109 | shrl $3,%ecx | |
110 | .p2align 4 | |
111 | .Lloop_8: | |
112 | decl %ecx | |
113 | movq %rax,(%rdi) | |
114 | leaq 8(%rdi),%rdi | |
115 | jnz .Lloop_8 | |
116 | ||
117 | .Lhandle_7: | |
5d7244e7 | 118 | andl $7,%edx |
7bcd3f34 AK |
119 | jz .Lende |
120 | .p2align 4 | |
121 | .Lloop_1: | |
5d7244e7 | 122 | decl %edx |
7bcd3f34 AK |
123 | movb %al,(%rdi) |
124 | leaq 1(%rdi),%rdi | |
125 | jnz .Lloop_1 | |
126 | ||
127 | .Lende: | |
128 | movq %r10,%rax | |
129 | ret | |
130 | ||
131 | .Lbad_alignment: | |
5d7244e7 | 132 | cmpq $7,%rdx |
7bcd3f34 AK |
133 | jbe .Lhandle_7 |
134 | movq %rax,(%rdi) /* unaligned store */ | |
135 | movq $8,%r8 | |
136 | subq %r9,%r8 | |
137 | addq %r8,%rdi | |
5d7244e7 | 138 | subq %r8,%rdx |
7bcd3f34 | 139 | jmp .Lafter_bad_alignment |
8d379dad | 140 | .Lfinal: |
84d95ad4 | 141 | ENDPROC(memset_orig) |