linux/arch/x86/include/asm/nops.h
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   1#ifndef _ASM_X86_NOPS_H
   2#define _ASM_X86_NOPS_H
   3
   4/*
   5 * Define nops for use with alternative() and for tracing.
   6 *
   7 * *_NOP5_ATOMIC must be a single instruction.
   8 */
   9
  10#define NOP_DS_PREFIX 0x3e
  11
  12/* generic versions from gas
  13   1: nop
  14   the following instructions are NOT nops in 64-bit mode,
  15   for 64-bit mode use K8 or P6 nops instead
  16   2: movl %esi,%esi
  17   3: leal 0x00(%esi),%esi
  18   4: leal 0x00(,%esi,1),%esi
  19   6: leal 0x00000000(%esi),%esi
  20   7: leal 0x00000000(,%esi,1),%esi
  21*/
  22#define GENERIC_NOP1 0x90
  23#define GENERIC_NOP2 0x89,0xf6
  24#define GENERIC_NOP3 0x8d,0x76,0x00
  25#define GENERIC_NOP4 0x8d,0x74,0x26,0x00
  26#define GENERIC_NOP5 GENERIC_NOP1,GENERIC_NOP4
  27#define GENERIC_NOP6 0x8d,0xb6,0x00,0x00,0x00,0x00
  28#define GENERIC_NOP7 0x8d,0xb4,0x26,0x00,0x00,0x00,0x00
  29#define GENERIC_NOP8 GENERIC_NOP1,GENERIC_NOP7
  30#define GENERIC_NOP5_ATOMIC NOP_DS_PREFIX,GENERIC_NOP4
  31
  32/* Opteron 64bit nops
  33   1: nop
  34   2: osp nop
  35   3: osp osp nop
  36   4: osp osp osp nop
  37*/
  38#define K8_NOP1 GENERIC_NOP1
  39#define K8_NOP2 0x66,K8_NOP1
  40#define K8_NOP3 0x66,K8_NOP2
  41#define K8_NOP4 0x66,K8_NOP3
  42#define K8_NOP5 K8_NOP3,K8_NOP2
  43#define K8_NOP6 K8_NOP3,K8_NOP3
  44#define K8_NOP7 K8_NOP4,K8_NOP3
  45#define K8_NOP8 K8_NOP4,K8_NOP4
  46#define K8_NOP5_ATOMIC 0x66,K8_NOP4
  47
  48/* K7 nops
  49   uses eax dependencies (arbitrary choice)
  50   1: nop
  51   2: movl %eax,%eax
  52   3: leal (,%eax,1),%eax
  53   4: leal 0x00(,%eax,1),%eax
  54   6: leal 0x00000000(%eax),%eax
  55   7: leal 0x00000000(,%eax,1),%eax
  56*/
  57#define K7_NOP1 GENERIC_NOP1
  58#define K7_NOP2 0x8b,0xc0
  59#define K7_NOP3 0x8d,0x04,0x20
  60#define K7_NOP4 0x8d,0x44,0x20,0x00
  61#define K7_NOP5 K7_NOP4,K7_NOP1
  62#define K7_NOP6 0x8d,0x80,0,0,0,0
  63#define K7_NOP7 0x8D,0x04,0x05,0,0,0,0
  64#define K7_NOP8 K7_NOP7,K7_NOP1
  65#define K7_NOP5_ATOMIC NOP_DS_PREFIX,K7_NOP4
  66
  67/* P6 nops
  68   uses eax dependencies (Intel-recommended choice)
  69   1: nop
  70   2: osp nop
  71   3: nopl (%eax)
  72   4: nopl 0x00(%eax)
  73   5: nopl 0x00(%eax,%eax,1)
  74   6: osp nopl 0x00(%eax,%eax,1)
  75   7: nopl 0x00000000(%eax)
  76   8: nopl 0x00000000(%eax,%eax,1)
  77   Note: All the above are assumed to be a single instruction.
  78        There is kernel code that depends on this.
  79*/
  80#define P6_NOP1 GENERIC_NOP1
  81#define P6_NOP2 0x66,0x90
  82#define P6_NOP3 0x0f,0x1f,0x00
  83#define P6_NOP4 0x0f,0x1f,0x40,0
  84#define P6_NOP5 0x0f,0x1f,0x44,0x00,0
  85#define P6_NOP6 0x66,0x0f,0x1f,0x44,0x00,0
  86#define P6_NOP7 0x0f,0x1f,0x80,0,0,0,0
  87#define P6_NOP8 0x0f,0x1f,0x84,0x00,0,0,0,0
  88#define P6_NOP5_ATOMIC P6_NOP5
  89
  90#define _ASM_MK_NOP(x) ".byte " __stringify(x) "\n"
  91
  92#if defined(CONFIG_MK7)
  93#define ASM_NOP1 _ASM_MK_NOP(K7_NOP1)
  94#define ASM_NOP2 _ASM_MK_NOP(K7_NOP2)
  95#define ASM_NOP3 _ASM_MK_NOP(K7_NOP3)
  96#define ASM_NOP4 _ASM_MK_NOP(K7_NOP4)
  97#define ASM_NOP5 _ASM_MK_NOP(K7_NOP5)
  98#define ASM_NOP6 _ASM_MK_NOP(K7_NOP6)
  99#define ASM_NOP7 _ASM_MK_NOP(K7_NOP7)
 100#define ASM_NOP8 _ASM_MK_NOP(K7_NOP8)
 101#define ASM_NOP5_ATOMIC _ASM_MK_NOP(K7_NOP5_ATOMIC)
 102#elif defined(CONFIG_X86_P6_NOP)
 103#define ASM_NOP1 _ASM_MK_NOP(P6_NOP1)
 104#define ASM_NOP2 _ASM_MK_NOP(P6_NOP2)
 105#define ASM_NOP3 _ASM_MK_NOP(P6_NOP3)
 106#define ASM_NOP4 _ASM_MK_NOP(P6_NOP4)
 107#define ASM_NOP5 _ASM_MK_NOP(P6_NOP5)
 108#define ASM_NOP6 _ASM_MK_NOP(P6_NOP6)
 109#define ASM_NOP7 _ASM_MK_NOP(P6_NOP7)
 110#define ASM_NOP8 _ASM_MK_NOP(P6_NOP8)
 111#define ASM_NOP5_ATOMIC _ASM_MK_NOP(P6_NOP5_ATOMIC)
 112#elif defined(CONFIG_X86_64)
 113#define ASM_NOP1 _ASM_MK_NOP(K8_NOP1)
 114#define ASM_NOP2 _ASM_MK_NOP(K8_NOP2)
 115#define ASM_NOP3 _ASM_MK_NOP(K8_NOP3)
 116#define ASM_NOP4 _ASM_MK_NOP(K8_NOP4)
 117#define ASM_NOP5 _ASM_MK_NOP(K8_NOP5)
 118#define ASM_NOP6 _ASM_MK_NOP(K8_NOP6)
 119#define ASM_NOP7 _ASM_MK_NOP(K8_NOP7)
 120#define ASM_NOP8 _ASM_MK_NOP(K8_NOP8)
 121#define ASM_NOP5_ATOMIC _ASM_MK_NOP(K8_NOP5_ATOMIC)
 122#else
 123#define ASM_NOP1 _ASM_MK_NOP(GENERIC_NOP1)
 124#define ASM_NOP2 _ASM_MK_NOP(GENERIC_NOP2)
 125#define ASM_NOP3 _ASM_MK_NOP(GENERIC_NOP3)
 126#define ASM_NOP4 _ASM_MK_NOP(GENERIC_NOP4)
 127#define ASM_NOP5 _ASM_MK_NOP(GENERIC_NOP5)
 128#define ASM_NOP6 _ASM_MK_NOP(GENERIC_NOP6)
 129#define ASM_NOP7 _ASM_MK_NOP(GENERIC_NOP7)
 130#define ASM_NOP8 _ASM_MK_NOP(GENERIC_NOP8)
 131#define ASM_NOP5_ATOMIC _ASM_MK_NOP(GENERIC_NOP5_ATOMIC)
 132#endif
 133
 134#define ASM_NOP_MAX 8
 135#define NOP_ATOMIC5 (ASM_NOP_MAX+1)     /* Entry for the 5-byte atomic NOP */
 136
 137#ifndef __ASSEMBLY__
 138extern const unsigned char * const *ideal_nops;
 139extern void arch_init_ideal_nops(void);
 140#endif
 141
 142#endif /* _ASM_X86_NOPS_H */
 143
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