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__
143extern const unsigned char * const *ideal_nops;
144extern void arch_init_ideal_nops(void);
145#endif
146
147#endif /* _ASM_X86_NOPS_H */
148