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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 | */ | |
4c690a1e | 62 | int (*read_std)(unsigned long addr, void *val, |
cebff02b | 63 | unsigned int bytes, struct kvm_vcpu *vcpu); |
6aa8b732 AK |
64 | |
65 | /* | |
66 | * write_std: Write bytes of standard (non-emulated/special) memory. | |
67 | * Used for stack operations, and others. | |
68 | * @addr: [IN ] Linear address to which to write. | |
69 | * @val: [IN ] Value to write to memory (low-order bytes used as | |
70 | * required). | |
71 | * @bytes: [IN ] Number of bytes to write to memory. | |
72 | */ | |
4c690a1e | 73 | int (*write_std)(unsigned long addr, const void *val, |
cebff02b | 74 | unsigned int bytes, struct kvm_vcpu *vcpu); |
6aa8b732 AK |
75 | |
76 | /* | |
77 | * read_emulated: Read bytes from emulated/special memory area. | |
78 | * @addr: [IN ] Linear address from which to read. | |
79 | * @val: [OUT] Value read from memory, zero-extended to 'u_long'. | |
80 | * @bytes: [IN ] Number of bytes to read from memory. | |
81 | */ | |
82 | int (*read_emulated) (unsigned long addr, | |
4c690a1e | 83 | void *val, |
6aa8b732 | 84 | unsigned int bytes, |
cebff02b | 85 | struct kvm_vcpu *vcpu); |
6aa8b732 AK |
86 | |
87 | /* | |
88 | * write_emulated: Read bytes from emulated/special memory area. | |
89 | * @addr: [IN ] Linear address to which to write. | |
90 | * @val: [IN ] Value to write to memory (low-order bytes used as | |
91 | * required). | |
92 | * @bytes: [IN ] Number of bytes to write to memory. | |
93 | */ | |
94 | int (*write_emulated) (unsigned long addr, | |
4c690a1e | 95 | const void *val, |
6aa8b732 | 96 | unsigned int bytes, |
cebff02b | 97 | struct kvm_vcpu *vcpu); |
6aa8b732 AK |
98 | |
99 | /* | |
100 | * cmpxchg_emulated: Emulate an atomic (LOCKed) CMPXCHG operation on an | |
101 | * emulated/special memory area. | |
102 | * @addr: [IN ] Linear address to access. | |
103 | * @old: [IN ] Value expected to be current at @addr. | |
104 | * @new: [IN ] Value to write to @addr. | |
105 | * @bytes: [IN ] Number of bytes to access using CMPXCHG. | |
106 | */ | |
107 | int (*cmpxchg_emulated) (unsigned long addr, | |
4c690a1e AK |
108 | const void *old, |
109 | const void *new, | |
6aa8b732 | 110 | unsigned int bytes, |
cebff02b | 111 | struct kvm_vcpu *vcpu); |
6aa8b732 | 112 | |
6aa8b732 AK |
113 | }; |
114 | ||
6aa8b732 AK |
115 | struct x86_emulate_ctxt { |
116 | /* Register state before/after emulation. */ | |
117 | struct kvm_vcpu *vcpu; | |
118 | ||
119 | /* Linear faulting address (if emulating a page-faulting instruction). */ | |
120 | unsigned long eflags; | |
121 | unsigned long cr2; | |
122 | ||
123 | /* Emulated execution mode, represented by an X86EMUL_MODE value. */ | |
124 | int mode; | |
125 | ||
126 | unsigned long cs_base; | |
127 | unsigned long ds_base; | |
128 | unsigned long es_base; | |
129 | unsigned long ss_base; | |
130 | unsigned long gs_base; | |
131 | unsigned long fs_base; | |
132 | }; | |
133 | ||
134 | /* Execution mode, passed to the emulator. */ | |
135 | #define X86EMUL_MODE_REAL 0 /* Real mode. */ | |
136 | #define X86EMUL_MODE_PROT16 2 /* 16-bit protected mode. */ | |
137 | #define X86EMUL_MODE_PROT32 4 /* 32-bit protected mode. */ | |
138 | #define X86EMUL_MODE_PROT64 8 /* 64-bit (long) mode. */ | |
139 | ||
140 | /* Host execution mode. */ | |
141 | #if defined(__i386__) | |
142 | #define X86EMUL_MODE_HOST X86EMUL_MODE_PROT32 | |
05b3e0c2 | 143 | #elif defined(CONFIG_X86_64) |
6aa8b732 AK |
144 | #define X86EMUL_MODE_HOST X86EMUL_MODE_PROT64 |
145 | #endif | |
146 | ||
147 | /* | |
148 | * x86_emulate_memop: Emulate an instruction that faulted attempting to | |
149 | * read/write a 'special' memory area. | |
150 | * Returns -1 on failure, 0 on success. | |
151 | */ | |
152 | int x86_emulate_memop(struct x86_emulate_ctxt *ctxt, | |
153 | struct x86_emulate_ops *ops); | |
154 | ||
6aa8b732 | 155 | #endif /* __X86_EMULATE_H__ */ |