arch/x86/include/asm/insn.h

   1 /* SPDX-License-Identifier: GPL-2.0-or-later */
   2 #ifndef _ASM_X86_INSN_H
   3 #define _ASM_X86_INSN_H
   4 /*
   5  * x86 instruction analysis
   6  *
   7  * Copyright (C) IBM Corporation, 2009
   8  */
   9
  10 /* insn_attr_t is defined in inat.h */
  11 #include <asm/inat.h>
  12
  13 struct insn_field {
  14         union {
  15                 insn_value_t value;
  16                 insn_byte_t bytes[4];
  17         };
  18         /* !0 if we've run insn_get_xxx() for this field */
  19         unsigned char got;
  20         unsigned char nbytes;
  21 };
  22
  23 struct insn {
  24         struct insn_field prefixes;     /*
  25                                          * Prefixes
  26                                          * prefixes.bytes[3]: last prefix
  27                                          */
  28         struct insn_field rex_prefix;   /* REX prefix */
  29         struct insn_field vex_prefix;   /* VEX prefix */
  30         struct insn_field opcode;       /*
  31                                          * opcode.bytes[0]: opcode1
  32                                          * opcode.bytes[1]: opcode2
  33                                          * opcode.bytes[2]: opcode3
  34                                          */
  35         struct insn_field modrm;
  36         struct insn_field sib;
  37         struct insn_field displacement;
  38         union {
  39                 struct insn_field immediate;
  40                 struct insn_field moffset1;     /* for 64bit MOV */
  41                 struct insn_field immediate1;   /* for 64bit imm or off16/32 */
  42         };
  43         union {
  44                 struct insn_field moffset2;     /* for 64bit MOV */
  45                 struct insn_field immediate2;   /* for 64bit imm or seg16 */
  46         };
  47
  48         int     emulate_prefix_size;
  49         insn_attr_t attr;
  50         unsigned char opnd_bytes;
  51         unsigned char addr_bytes;
  52         unsigned char length;
  53         unsigned char x86_64;
  54
  55         const insn_byte_t *kaddr;       /* kernel address of insn to analyze */
  56         const insn_byte_t *end_kaddr;   /* kernel address of last insn in buffer */
  57         const insn_byte_t *next_byte;
  58 };
  59
  60 #define MAX_INSN_SIZE   15
  61
  62 #define X86_MODRM_MOD(modrm) (((modrm) & 0xc0) >> 6)
  63 #define X86_MODRM_REG(modrm) (((modrm) & 0x38) >> 3)
  64 #define X86_MODRM_RM(modrm) ((modrm) & 0x07)
  65
  66 #define X86_SIB_SCALE(sib) (((sib) & 0xc0) >> 6)
  67 #define X86_SIB_INDEX(sib) (((sib) & 0x38) >> 3)
  68 #define X86_SIB_BASE(sib) ((sib) & 0x07)
  69
  70 #define X86_REX_W(rex) ((rex) & 8)
  71 #define X86_REX_R(rex) ((rex) & 4)
  72 #define X86_REX_X(rex) ((rex) & 2)
  73 #define X86_REX_B(rex) ((rex) & 1)
  74
  75 /* VEX bit flags  */
  76 #define X86_VEX_W(vex)  ((vex) & 0x80)  /* VEX3 Byte2 */
  77 #define X86_VEX_R(vex)  ((vex) & 0x80)  /* VEX2/3 Byte1 */
  78 #define X86_VEX_X(vex)  ((vex) & 0x40)  /* VEX3 Byte1 */
  79 #define X86_VEX_B(vex)  ((vex) & 0x20)  /* VEX3 Byte1 */
  80 #define X86_VEX_L(vex)  ((vex) & 0x04)  /* VEX3 Byte2, VEX2 Byte1 */
  81 /* VEX bit fields */
  82 #define X86_EVEX_M(vex) ((vex) & 0x03)          /* EVEX Byte1 */
  83 #define X86_VEX3_M(vex) ((vex) & 0x1f)          /* VEX3 Byte1 */
  84 #define X86_VEX2_M      1                       /* VEX2.M always 1 */
  85 #define X86_VEX_V(vex)  (((vex) & 0x78) >> 3)   /* VEX3 Byte2, VEX2 Byte1 */
  86 #define X86_VEX_P(vex)  ((vex) & 0x03)          /* VEX3 Byte2, VEX2 Byte1 */
  87 #define X86_VEX_M_MAX   0x1f                    /* VEX3.M Maximum value */
  88
  89 extern void insn_init(struct insn *insn, const void *kaddr, int buf_len, int x86_64);
  90 extern void insn_get_prefixes(struct insn *insn);
  91 extern void insn_get_opcode(struct insn *insn);
  92 extern void insn_get_modrm(struct insn *insn);
  93 extern void insn_get_sib(struct insn *insn);
  94 extern void insn_get_displacement(struct insn *insn);
  95 extern void insn_get_immediate(struct insn *insn);
  96 extern void insn_get_length(struct insn *insn);
  97
  98 /* Attribute will be determined after getting ModRM (for opcode groups) */
  99 static inline void insn_get_attribute(struct insn *insn)
 100 {
 101         insn_get_modrm(insn);
 102 }
 103
 104 /* Instruction uses RIP-relative addressing */
 105 extern int insn_rip_relative(struct insn *insn);
 106
 107 /* Init insn for kernel text */
 108 static inline void kernel_insn_init(struct insn *insn,
 109                                     const void *kaddr, int buf_len)
 110 {
 111 #ifdef CONFIG_X86_64
 112         insn_init(insn, kaddr, buf_len, 1);
 113 #else /* CONFIG_X86_32 */
 114         insn_init(insn, kaddr, buf_len, 0);
 115 #endif
 116 }
 117
 118 static inline int insn_is_avx(struct insn *insn)
 119 {
 120         if (!insn->prefixes.got)
 121                 insn_get_prefixes(insn);
 122         return (insn->vex_prefix.value != 0);
 123 }
 124
 125 static inline int insn_is_evex(struct insn *insn)
 126 {
 127         if (!insn->prefixes.got)
 128                 insn_get_prefixes(insn);
 129         return (insn->vex_prefix.nbytes == 4);
 130 }
 131
 132 static inline int insn_has_emulate_prefix(struct insn *insn)
 133 {
 134         return !!insn->emulate_prefix_size;
 135 }
 136
 137 /* Ensure this instruction is decoded completely */
 138 static inline int insn_complete(struct insn *insn)
 139 {
 140         return insn->opcode.got && insn->modrm.got && insn->sib.got &&
 141                 insn->displacement.got && insn->immediate.got;
 142 }
 143
 144 static inline insn_byte_t insn_vex_m_bits(struct insn *insn)
 145 {
 146         if (insn->vex_prefix.nbytes == 2)       /* 2 bytes VEX */
 147                 return X86_VEX2_M;
 148         else if (insn->vex_prefix.nbytes == 3)  /* 3 bytes VEX */
 149                 return X86_VEX3_M(insn->vex_prefix.bytes[1]);
 150         else                                    /* EVEX */
 151                 return X86_EVEX_M(insn->vex_prefix.bytes[1]);
 152 }
 153
 154 static inline insn_byte_t insn_vex_p_bits(struct insn *insn)
 155 {
 156         if (insn->vex_prefix.nbytes == 2)       /* 2 bytes VEX */
 157                 return X86_VEX_P(insn->vex_prefix.bytes[1]);
 158         else
 159                 return X86_VEX_P(insn->vex_prefix.bytes[2]);
 160 }
 161
 162 /* Get the last prefix id from last prefix or VEX prefix */
 163 static inline int insn_last_prefix_id(struct insn *insn)
 164 {
 165         if (insn_is_avx(insn))
 166                 return insn_vex_p_bits(insn);   /* VEX_p is a SIMD prefix id */
 167
 168         if (insn->prefixes.bytes[3])
 169                 return inat_get_last_prefix_id(insn->prefixes.bytes[3]);
 170
 171         return 0;
 172 }
 173
 174 /* Offset of each field from kaddr */
 175 static inline int insn_offset_rex_prefix(struct insn *insn)
 176 {
 177         return insn->prefixes.nbytes;
 178 }
 179 static inline int insn_offset_vex_prefix(struct insn *insn)
 180 {
 181         return insn_offset_rex_prefix(insn) + insn->rex_prefix.nbytes;
 182 }
 183 static inline int insn_offset_opcode(struct insn *insn)
 184 {
 185         return insn_offset_vex_prefix(insn) + insn->vex_prefix.nbytes;
 186 }
 187 static inline int insn_offset_modrm(struct insn *insn)
 188 {
 189         return insn_offset_opcode(insn) + insn->opcode.nbytes;
 190 }
 191 static inline int insn_offset_sib(struct insn *insn)
 192 {
 193         return insn_offset_modrm(insn) + insn->modrm.nbytes;
 194 }
 195 static inline int insn_offset_displacement(struct insn *insn)
 196 {
 197         return insn_offset_sib(insn) + insn->sib.nbytes;
 198 }
 199 static inline int insn_offset_immediate(struct insn *insn)
 200 {
 201         return insn_offset_displacement(insn) + insn->displacement.nbytes;
 202 }
 203
 204 /**
 205  * for_each_insn_prefix() -- Iterate prefixes in the instruction
 206  * @insn: Pointer to struct insn.
 207  * @idx:  Index storage.
 208  * @prefix: Prefix byte.
 209  *
 210  * Iterate prefix bytes of given @insn. Each prefix byte is stored in @prefix
 211  * and the index is stored in @idx (note that this @idx is just for a cursor,
 212  * do not change it.)
 213  * Since prefixes.nbytes can be bigger than 4 if some prefixes
 214  * are repeated, it cannot be used for looping over the prefixes.
 215  */
 216 #define for_each_insn_prefix(insn, idx, prefix) \
 217         for (idx = 0; idx < ARRAY_SIZE(insn->prefixes.bytes) && (prefix = insn->prefixes.bytes[idx]) != 0; idx++)
 218
 219 #define POP_SS_OPCODE 0x1f
 220 #define MOV_SREG_OPCODE 0x8e
 221
 222 /*
 223  * Intel SDM Vol.3A 6.8.3 states;
 224  * "Any single-step trap that would be delivered following the MOV to SS
 225  * instruction or POP to SS instruction (because EFLAGS.TF is 1) is
 226  * suppressed."
 227  * This function returns true if @insn is MOV SS or POP SS. On these
 228  * instructions, single stepping is suppressed.
 229  */
 230 static inline int insn_masking_exception(struct insn *insn)
 231 {
 232         return insn->opcode.bytes[0] == POP_SS_OPCODE ||
 233                 (insn->opcode.bytes[0] == MOV_SREG_OPCODE &&
 234                  X86_MODRM_REG(insn->modrm.bytes[0]) == 2);
 235 }
 236
 237 #endif /* _ASM_X86_INSN_H */