1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _ASM_X86_NOPS_H
3 #define _ASM_X86_NOPS_H
4 
5 /*
6  * Define nops for use with alternative() and for tracing.
7  *
8  * *_NOP5_ATOMIC must be a single instruction.
9  */
10 
11 #define NOP_DS_PREFIX 0x3e
12 
13 /* generic versions from gas
14    1: nop
15    the following instructions are NOT nops in 64-bit mode,
16    for 64-bit mode use K8 or P6 nops instead
17    2: movl %esi,%esi
18    3: leal 0x00(%esi),%esi
19    4: leal 0x00(,%esi,1),%esi
20    6: leal 0x00000000(%esi),%esi
21    7: leal 0x00000000(,%esi,1),%esi
22 */
23 #define GENERIC_NOP1 0x90
24 #define GENERIC_NOP2 0x89,0xf6
25 #define GENERIC_NOP3 0x8d,0x76,0x00
26 #define GENERIC_NOP4 0x8d,0x74,0x26,0x00
27 #define GENERIC_NOP5 GENERIC_NOP1,GENERIC_NOP4
28 #define GENERIC_NOP6 0x8d,0xb6,0x00,0x00,0x00,0x00
29 #define GENERIC_NOP7 0x8d,0xb4,0x26,0x00,0x00,0x00,0x00
30 #define GENERIC_NOP8 GENERIC_NOP1,GENERIC_NOP7
31 #define GENERIC_NOP5_ATOMIC NOP_DS_PREFIX,GENERIC_NOP4
32 
33 /* Opteron 64bit nops
34    1: nop
35    2: osp nop
36    3: osp osp nop
37    4: osp osp osp nop
38 */
39 #define K8_NOP1 GENERIC_NOP1
40 #define K8_NOP2	0x66,K8_NOP1
41 #define K8_NOP3	0x66,K8_NOP2
42 #define K8_NOP4	0x66,K8_NOP3
43 #define K8_NOP5	K8_NOP3,K8_NOP2
44 #define K8_NOP6	K8_NOP3,K8_NOP3
45 #define K8_NOP7	K8_NOP4,K8_NOP3
46 #define K8_NOP8	K8_NOP4,K8_NOP4
47 #define K8_NOP5_ATOMIC 0x66,K8_NOP4
48 
49 /* K7 nops
50    uses eax dependencies (arbitrary choice)
51    1: nop
52    2: movl %eax,%eax
53    3: leal (,%eax,1),%eax
54    4: leal 0x00(,%eax,1),%eax
55    6: leal 0x00000000(%eax),%eax
56    7: leal 0x00000000(,%eax,1),%eax
57 */
58 #define K7_NOP1	GENERIC_NOP1
59 #define K7_NOP2	0x8b,0xc0
60 #define K7_NOP3	0x8d,0x04,0x20
61 #define K7_NOP4	0x8d,0x44,0x20,0x00
62 #define K7_NOP5	K7_NOP4,K7_NOP1
63 #define K7_NOP6	0x8d,0x80,0,0,0,0
64 #define K7_NOP7	0x8D,0x04,0x05,0,0,0,0
65 #define K7_NOP8	K7_NOP7,K7_NOP1
66 #define K7_NOP5_ATOMIC NOP_DS_PREFIX,K7_NOP4
67 
68 /* P6 nops
69    uses eax dependencies (Intel-recommended choice)
70    1: nop
71    2: osp nop
72    3: nopl (%eax)
73    4: nopl 0x00(%eax)
74    5: nopl 0x00(%eax,%eax,1)
75    6: osp nopl 0x00(%eax,%eax,1)
76    7: nopl 0x00000000(%eax)
77    8: nopl 0x00000000(%eax,%eax,1)
78    Note: All the above are assumed to be a single instruction.
79 	There is kernel code that depends on this.
80 */
81 #define P6_NOP1	GENERIC_NOP1
82 #define P6_NOP2	0x66,0x90
83 #define P6_NOP3	0x0f,0x1f,0x00
84 #define P6_NOP4	0x0f,0x1f,0x40,0
85 #define P6_NOP5	0x0f,0x1f,0x44,0x00,0
86 #define P6_NOP6	0x66,0x0f,0x1f,0x44,0x00,0
87 #define P6_NOP7	0x0f,0x1f,0x80,0,0,0,0
88 #define P6_NOP8	0x0f,0x1f,0x84,0x00,0,0,0,0
89 #define P6_NOP5_ATOMIC P6_NOP5
90 
91 #ifdef __ASSEMBLY__
92 #define _ASM_MK_NOP(x) .byte x
93 #else
94 #define _ASM_MK_NOP(x) ".byte " __stringify(x) "\n"
95 #endif
96 
97 #if defined(CONFIG_MK7)
98 #define ASM_NOP1 _ASM_MK_NOP(K7_NOP1)
99 #define ASM_NOP2 _ASM_MK_NOP(K7_NOP2)
100 #define ASM_NOP3 _ASM_MK_NOP(K7_NOP3)
101 #define ASM_NOP4 _ASM_MK_NOP(K7_NOP4)
102 #define ASM_NOP5 _ASM_MK_NOP(K7_NOP5)
103 #define ASM_NOP6 _ASM_MK_NOP(K7_NOP6)
104 #define ASM_NOP7 _ASM_MK_NOP(K7_NOP7)
105 #define ASM_NOP8 _ASM_MK_NOP(K7_NOP8)
106 #define ASM_NOP5_ATOMIC _ASM_MK_NOP(K7_NOP5_ATOMIC)
107 #elif defined(CONFIG_X86_P6_NOP)
108 #define ASM_NOP1 _ASM_MK_NOP(P6_NOP1)
109 #define ASM_NOP2 _ASM_MK_NOP(P6_NOP2)
110 #define ASM_NOP3 _ASM_MK_NOP(P6_NOP3)
111 #define ASM_NOP4 _ASM_MK_NOP(P6_NOP4)
112 #define ASM_NOP5 _ASM_MK_NOP(P6_NOP5)
113 #define ASM_NOP6 _ASM_MK_NOP(P6_NOP6)
114 #define ASM_NOP7 _ASM_MK_NOP(P6_NOP7)
115 #define ASM_NOP8 _ASM_MK_NOP(P6_NOP8)
116 #define ASM_NOP5_ATOMIC _ASM_MK_NOP(P6_NOP5_ATOMIC)
117 #elif defined(CONFIG_X86_64)
118 #define ASM_NOP1 _ASM_MK_NOP(K8_NOP1)
119 #define ASM_NOP2 _ASM_MK_NOP(K8_NOP2)
120 #define ASM_NOP3 _ASM_MK_NOP(K8_NOP3)
121 #define ASM_NOP4 _ASM_MK_NOP(K8_NOP4)
122 #define ASM_NOP5 _ASM_MK_NOP(K8_NOP5)
123 #define ASM_NOP6 _ASM_MK_NOP(K8_NOP6)
124 #define ASM_NOP7 _ASM_MK_NOP(K8_NOP7)
125 #define ASM_NOP8 _ASM_MK_NOP(K8_NOP8)
126 #define ASM_NOP5_ATOMIC _ASM_MK_NOP(K8_NOP5_ATOMIC)
127 #else
128 #define ASM_NOP1 _ASM_MK_NOP(GENERIC_NOP1)
129 #define ASM_NOP2 _ASM_MK_NOP(GENERIC_NOP2)
130 #define ASM_NOP3 _ASM_MK_NOP(GENERIC_NOP3)
131 #define ASM_NOP4 _ASM_MK_NOP(GENERIC_NOP4)
132 #define ASM_NOP5 _ASM_MK_NOP(GENERIC_NOP5)
133 #define ASM_NOP6 _ASM_MK_NOP(GENERIC_NOP6)
134 #define ASM_NOP7 _ASM_MK_NOP(GENERIC_NOP7)
135 #define ASM_NOP8 _ASM_MK_NOP(GENERIC_NOP8)
136 #define ASM_NOP5_ATOMIC _ASM_MK_NOP(GENERIC_NOP5_ATOMIC)
137 #endif
138 
139 #define ASM_NOP_MAX 8
140 #define NOP_ATOMIC5 (ASM_NOP_MAX+1)	/* Entry for the 5-byte atomic NOP */
141 
142 #ifndef __ASSEMBLY__
143 extern const unsigned char * const *ideal_nops;
144 extern void arch_init_ideal_nops(void);
145 #endif
146 
147 #endif /* _ASM_X86_NOPS_H */
148