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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 | ||
14 | struct 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 */ | |
54 | struct 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, | |
63 | unsigned long *val, | |
64 | unsigned int bytes, struct x86_emulate_ctxt * ctxt); | |
65 | ||
66 | /* | |
67 | * write_std: Write bytes of standard (non-emulated/special) memory. | |
68 | * Used for stack operations, and others. | |
69 | * @addr: [IN ] Linear address to which to write. | |
70 | * @val: [IN ] Value to write to memory (low-order bytes used as | |
71 | * required). | |
72 | * @bytes: [IN ] Number of bytes to write to memory. | |
73 | */ | |
74 | int (*write_std)(unsigned long addr, | |
75 | unsigned long val, | |
76 | unsigned int bytes, struct x86_emulate_ctxt * ctxt); | |
77 | ||
78 | /* | |
79 | * read_emulated: Read bytes from emulated/special memory area. | |
80 | * @addr: [IN ] Linear address from which to read. | |
81 | * @val: [OUT] Value read from memory, zero-extended to 'u_long'. | |
82 | * @bytes: [IN ] Number of bytes to read from memory. | |
83 | */ | |
84 | int (*read_emulated) (unsigned long addr, | |
85 | unsigned long *val, | |
86 | unsigned int bytes, | |
87 | struct x86_emulate_ctxt * ctxt); | |
88 | ||
89 | /* | |
90 | * write_emulated: Read bytes from emulated/special memory area. | |
91 | * @addr: [IN ] Linear address to which to write. | |
92 | * @val: [IN ] Value to write to memory (low-order bytes used as | |
93 | * required). | |
94 | * @bytes: [IN ] Number of bytes to write to memory. | |
95 | */ | |
96 | int (*write_emulated) (unsigned long addr, | |
97 | unsigned long val, | |
98 | unsigned int bytes, | |
99 | struct x86_emulate_ctxt * ctxt); | |
100 | ||
101 | /* | |
102 | * cmpxchg_emulated: Emulate an atomic (LOCKed) CMPXCHG operation on an | |
103 | * emulated/special memory area. | |
104 | * @addr: [IN ] Linear address to access. | |
105 | * @old: [IN ] Value expected to be current at @addr. | |
106 | * @new: [IN ] Value to write to @addr. | |
107 | * @bytes: [IN ] Number of bytes to access using CMPXCHG. | |
108 | */ | |
109 | int (*cmpxchg_emulated) (unsigned long addr, | |
110 | unsigned long old, | |
111 | unsigned long new, | |
112 | unsigned int bytes, | |
113 | struct x86_emulate_ctxt * ctxt); | |
114 | ||
115 | /* | |
116 | * cmpxchg8b_emulated: Emulate an atomic (LOCKed) CMPXCHG8B operation on an | |
117 | * emulated/special memory area. | |
118 | * @addr: [IN ] Linear address to access. | |
119 | * @old: [IN ] Value expected to be current at @addr. | |
120 | * @new: [IN ] Value to write to @addr. | |
121 | * NOTES: | |
122 | * 1. This function is only ever called when emulating a real CMPXCHG8B. | |
123 | * 2. This function is *never* called on x86/64 systems. | |
124 | * 2. Not defining this function (i.e., specifying NULL) is equivalent | |
125 | * to defining a function that always returns X86EMUL_UNHANDLEABLE. | |
126 | */ | |
127 | int (*cmpxchg8b_emulated) (unsigned long addr, | |
128 | unsigned long old_lo, | |
129 | unsigned long old_hi, | |
130 | unsigned long new_lo, | |
131 | unsigned long new_hi, | |
132 | struct x86_emulate_ctxt * ctxt); | |
133 | }; | |
134 | ||
135 | struct cpu_user_regs; | |
136 | ||
137 | struct x86_emulate_ctxt { | |
138 | /* Register state before/after emulation. */ | |
139 | struct kvm_vcpu *vcpu; | |
140 | ||
141 | /* Linear faulting address (if emulating a page-faulting instruction). */ | |
142 | unsigned long eflags; | |
143 | unsigned long cr2; | |
144 | ||
145 | /* Emulated execution mode, represented by an X86EMUL_MODE value. */ | |
146 | int mode; | |
147 | ||
148 | unsigned long cs_base; | |
149 | unsigned long ds_base; | |
150 | unsigned long es_base; | |
151 | unsigned long ss_base; | |
152 | unsigned long gs_base; | |
153 | unsigned long fs_base; | |
154 | }; | |
155 | ||
156 | /* Execution mode, passed to the emulator. */ | |
157 | #define X86EMUL_MODE_REAL 0 /* Real mode. */ | |
158 | #define X86EMUL_MODE_PROT16 2 /* 16-bit protected mode. */ | |
159 | #define X86EMUL_MODE_PROT32 4 /* 32-bit protected mode. */ | |
160 | #define X86EMUL_MODE_PROT64 8 /* 64-bit (long) mode. */ | |
161 | ||
162 | /* Host execution mode. */ | |
163 | #if defined(__i386__) | |
164 | #define X86EMUL_MODE_HOST X86EMUL_MODE_PROT32 | |
165 | #elif defined(__x86_64__) | |
166 | #define X86EMUL_MODE_HOST X86EMUL_MODE_PROT64 | |
167 | #endif | |
168 | ||
169 | /* | |
170 | * x86_emulate_memop: Emulate an instruction that faulted attempting to | |
171 | * read/write a 'special' memory area. | |
172 | * Returns -1 on failure, 0 on success. | |
173 | */ | |
174 | int x86_emulate_memop(struct x86_emulate_ctxt *ctxt, | |
175 | struct x86_emulate_ops *ops); | |
176 | ||
177 | /* | |
178 | * Given the 'reg' portion of a ModRM byte, and a register block, return a | |
179 | * pointer into the block that addresses the relevant register. | |
180 | * @highbyte_regs specifies whether to decode AH,CH,DH,BH. | |
181 | */ | |
182 | void *decode_register(u8 modrm_reg, unsigned long *regs, | |
183 | int highbyte_regs); | |
184 | ||
185 | #endif /* __X86_EMULATE_H__ */ |