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1/******************************************************************************
2 * x86_emulate.h
3 *
4 * Generic x86 (32-bit and 64-bit) instruction decoder and emulator.
5 *
6 * Copyright (c) 2005 Keir Fraser
7 *
8 * From: xen-unstable 10676:af9809f51f81a3c43f276f00c81a52ef558afda4
9 */
10
11#ifndef __X86_EMULATE_H__
12#define __X86_EMULATE_H__
13
14struct x86_emulate_ctxt;
15
16/*
17 * x86_emulate_ops:
18 *
19 * These operations represent the instruction emulator's interface to memory.
20 * There are two categories of operation: those that act on ordinary memory
21 * regions (*_std), and those that act on memory regions known to require
22 * special treatment or emulation (*_emulated).
23 *
24 * The emulator assumes that an instruction accesses only one 'emulated memory'
25 * location, that this location is the given linear faulting address (cr2), and
26 * that this is one of the instruction's data operands. Instruction fetches and
27 * stack operations are assumed never to access emulated memory. The emulator
28 * automatically deduces which operand of a string-move operation is accessing
29 * emulated memory, and assumes that the other operand accesses normal memory.
30 *
31 * NOTES:
32 * 1. The emulator isn't very smart about emulated vs. standard memory.
33 * 'Emulated memory' access addresses should be checked for sanity.
34 * 'Normal memory' accesses may fault, and the caller must arrange to
35 * detect and handle reentrancy into the emulator via recursive faults.
36 * Accesses may be unaligned and may cross page boundaries.
37 * 2. If the access fails (cannot emulate, or a standard access faults) then
38 * it is up to the memop to propagate the fault to the guest VM via
39 * some out-of-band mechanism, unknown to the emulator. The memop signals
40 * failure by returning X86EMUL_PROPAGATE_FAULT to the emulator, which will
41 * then immediately bail.
42 * 3. Valid access sizes are 1, 2, 4 and 8 bytes. On x86/32 systems only
43 * cmpxchg8b_emulated need support 8-byte accesses.
44 * 4. The emulator cannot handle 64-bit mode emulation on an x86/32 system.
45 */
46/* Access completed successfully: continue emulation as normal. */
47#define X86EMUL_CONTINUE 0
48/* Access is unhandleable: bail from emulation and return error to caller. */
49#define X86EMUL_UNHANDLEABLE 1
50/* Terminate emulation but return success to the caller. */
51#define X86EMUL_PROPAGATE_FAULT 2 /* propagate a generated fault to guest */
52#define X86EMUL_RETRY_INSTR 2 /* retry the instruction for some reason */
53#define X86EMUL_CMPXCHG_FAILED 2 /* cmpxchg did not see expected value */
54struct x86_emulate_ops {
55 /*
56 * read_std: Read bytes of standard (non-emulated/special) memory.
57 * Used for instruction fetch, stack operations, and others.
58 * @addr: [IN ] Linear address from which to read.
59 * @val: [OUT] Value read from memory, zero-extended to 'u_long'.
60 * @bytes: [IN ] Number of bytes to read from memory.
61 */
62 int (*read_std)(unsigned long addr, void *val,
63 unsigned int bytes, struct kvm_vcpu *vcpu);
64
65 /*
66 * read_emulated: Read bytes from emulated/special memory area.
67 * @addr: [IN ] Linear address from which to read.
68 * @val: [OUT] Value read from memory, zero-extended to 'u_long'.
69 * @bytes: [IN ] Number of bytes to read from memory.
70 */
71 int (*read_emulated)(unsigned long addr,
72 void *val,
73 unsigned int bytes,
74 struct kvm_vcpu *vcpu);
75
76 /*
77 * write_emulated: Read bytes from emulated/special memory area.
78 * @addr: [IN ] Linear address to which to write.
79 * @val: [IN ] Value to write to memory (low-order bytes used as
80 * required).
81 * @bytes: [IN ] Number of bytes to write to memory.
82 */
83 int (*write_emulated)(unsigned long addr,
84 const void *val,
85 unsigned int bytes,
86 struct kvm_vcpu *vcpu);
87
88 /*
89 * cmpxchg_emulated: Emulate an atomic (LOCKed) CMPXCHG operation on an
90 * emulated/special memory area.
91 * @addr: [IN ] Linear address to access.
92 * @old: [IN ] Value expected to be current at @addr.
93 * @new: [IN ] Value to write to @addr.
94 * @bytes: [IN ] Number of bytes to access using CMPXCHG.
95 */
96 int (*cmpxchg_emulated)(unsigned long addr,
97 const void *old,
98 const void *new,
99 unsigned int bytes,
100 struct kvm_vcpu *vcpu);
101
102};
103
104/* Type, address-of, and value of an instruction's operand. */
105struct operand {
106 enum { OP_REG, OP_MEM, OP_IMM, OP_NONE } type;
107 unsigned int bytes;
108 unsigned long val, orig_val, *ptr;
109};
110
111struct fetch_cache {
112 u8 data[15];
113 unsigned long start;
114 unsigned long end;
115};
116
117struct decode_cache {
118 u8 twobyte;
119 u8 b;
120 u8 lock_prefix;
121 u8 rep_prefix;
122 u8 op_bytes;
123 u8 ad_bytes;
124 u8 rex_prefix;
125 struct operand src;
126 struct operand dst;
127 bool has_seg_override;
128 u8 seg_override;
129 unsigned int d;
130 unsigned long regs[NR_VCPU_REGS];
131 unsigned long eip;
132 /* modrm */
133 u8 modrm;
134 u8 modrm_mod;
135 u8 modrm_reg;
136 u8 modrm_rm;
137 u8 use_modrm_ea;
138 bool rip_relative;
139 unsigned long modrm_ea;
140 void *modrm_ptr;
141 unsigned long modrm_val;
142 struct fetch_cache fetch;
143};
144
145struct x86_emulate_ctxt {
146 /* Register state before/after emulation. */
147 struct kvm_vcpu *vcpu;
148
149 /* Linear faulting address (if emulating a page-faulting instruction) */
150 unsigned long eflags;
151
152 /* Emulated execution mode, represented by an X86EMUL_MODE value. */
153 int mode;
154
155 u32 cs_base;
156
157 /* decode cache */
158
159 struct decode_cache decode;
160};
161
162/* Repeat String Operation Prefix */
163#define REPE_PREFIX 1
164#define REPNE_PREFIX 2
165
166/* Execution mode, passed to the emulator. */
167#define X86EMUL_MODE_REAL 0 /* Real mode. */
168#define X86EMUL_MODE_PROT16 2 /* 16-bit protected mode. */
169#define X86EMUL_MODE_PROT32 4 /* 32-bit protected mode. */
170#define X86EMUL_MODE_PROT64 8 /* 64-bit (long) mode. */
171
172/* Host execution mode. */
173#if defined(__i386__)
174#define X86EMUL_MODE_HOST X86EMUL_MODE_PROT32
175#elif defined(CONFIG_X86_64)
176#define X86EMUL_MODE_HOST X86EMUL_MODE_PROT64
177#endif
178
179int x86_decode_insn(struct x86_emulate_ctxt *ctxt,
180 struct x86_emulate_ops *ops);
181int x86_emulate_insn(struct x86_emulate_ctxt *ctxt,
182 struct x86_emulate_ops *ops);
183
184#endif /* __X86_EMULATE_H__ */