166 lines
6.2 KiB
C
166 lines
6.2 KiB
C
/******************************************************************************
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* x86_emulate.h
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*
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* Generic x86 (32-bit and 64-bit) instruction decoder and emulator.
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*
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* Copyright (c) 2005 Keir Fraser
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*
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* From: xen-unstable 10676:af9809f51f81a3c43f276f00c81a52ef558afda4
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*/
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#ifndef __X86_EMULATE_H__
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#define __X86_EMULATE_H__
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struct x86_emulate_ctxt;
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/*
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* x86_emulate_ops:
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*
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* These operations represent the instruction emulator's interface to memory.
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* There are two categories of operation: those that act on ordinary memory
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* regions (*_std), and those that act on memory regions known to require
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* special treatment or emulation (*_emulated).
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*
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* The emulator assumes that an instruction accesses only one 'emulated memory'
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* location, that this location is the given linear faulting address (cr2), and
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* that this is one of the instruction's data operands. Instruction fetches and
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* stack operations are assumed never to access emulated memory. The emulator
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* automatically deduces which operand of a string-move operation is accessing
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* emulated memory, and assumes that the other operand accesses normal memory.
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*
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* NOTES:
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* 1. The emulator isn't very smart about emulated vs. standard memory.
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* 'Emulated memory' access addresses should be checked for sanity.
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* 'Normal memory' accesses may fault, and the caller must arrange to
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* detect and handle reentrancy into the emulator via recursive faults.
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* Accesses may be unaligned and may cross page boundaries.
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* 2. If the access fails (cannot emulate, or a standard access faults) then
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* it is up to the memop to propagate the fault to the guest VM via
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* some out-of-band mechanism, unknown to the emulator. The memop signals
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* failure by returning X86EMUL_PROPAGATE_FAULT to the emulator, which will
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* then immediately bail.
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* 3. Valid access sizes are 1, 2, 4 and 8 bytes. On x86/32 systems only
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* cmpxchg8b_emulated need support 8-byte accesses.
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* 4. The emulator cannot handle 64-bit mode emulation on an x86/32 system.
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*/
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/* Access completed successfully: continue emulation as normal. */
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#define X86EMUL_CONTINUE 0
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/* Access is unhandleable: bail from emulation and return error to caller. */
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#define X86EMUL_UNHANDLEABLE 1
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/* Terminate emulation but return success to the caller. */
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#define X86EMUL_PROPAGATE_FAULT 2 /* propagate a generated fault to guest */
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#define X86EMUL_RETRY_INSTR 2 /* retry the instruction for some reason */
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#define X86EMUL_CMPXCHG_FAILED 2 /* cmpxchg did not see expected value */
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struct x86_emulate_ops {
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/*
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* read_std: Read bytes of standard (non-emulated/special) memory.
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* Used for instruction fetch, stack operations, and others.
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* @addr: [IN ] Linear address from which to read.
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* @val: [OUT] Value read from memory, zero-extended to 'u_long'.
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* @bytes: [IN ] Number of bytes to read from memory.
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*/
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int (*read_std)(unsigned long addr, void *val,
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unsigned int bytes, struct x86_emulate_ctxt * ctxt);
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/*
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* write_std: Write bytes of standard (non-emulated/special) memory.
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* Used for stack operations, and others.
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* @addr: [IN ] Linear address to which to write.
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* @val: [IN ] Value to write to memory (low-order bytes used as
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* required).
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* @bytes: [IN ] Number of bytes to write to memory.
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*/
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int (*write_std)(unsigned long addr, const void *val,
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unsigned int bytes, struct x86_emulate_ctxt * ctxt);
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/*
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* read_emulated: Read bytes from emulated/special memory area.
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* @addr: [IN ] Linear address from which to read.
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* @val: [OUT] Value read from memory, zero-extended to 'u_long'.
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* @bytes: [IN ] Number of bytes to read from memory.
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*/
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int (*read_emulated) (unsigned long addr,
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void *val,
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unsigned int bytes,
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struct x86_emulate_ctxt * ctxt);
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/*
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* write_emulated: Read bytes from emulated/special memory area.
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* @addr: [IN ] Linear address to which to write.
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* @val: [IN ] Value to write to memory (low-order bytes used as
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* required).
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* @bytes: [IN ] Number of bytes to write to memory.
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*/
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int (*write_emulated) (unsigned long addr,
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const void *val,
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unsigned int bytes,
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struct x86_emulate_ctxt * ctxt);
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/*
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* cmpxchg_emulated: Emulate an atomic (LOCKed) CMPXCHG operation on an
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* emulated/special memory area.
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* @addr: [IN ] Linear address to access.
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* @old: [IN ] Value expected to be current at @addr.
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* @new: [IN ] Value to write to @addr.
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* @bytes: [IN ] Number of bytes to access using CMPXCHG.
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*/
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int (*cmpxchg_emulated) (unsigned long addr,
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const void *old,
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const void *new,
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unsigned int bytes,
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struct x86_emulate_ctxt * ctxt);
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};
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struct cpu_user_regs;
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struct x86_emulate_ctxt {
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/* Register state before/after emulation. */
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struct kvm_vcpu *vcpu;
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/* Linear faulting address (if emulating a page-faulting instruction). */
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unsigned long eflags;
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unsigned long cr2;
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/* Emulated execution mode, represented by an X86EMUL_MODE value. */
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int mode;
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unsigned long cs_base;
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unsigned long ds_base;
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unsigned long es_base;
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unsigned long ss_base;
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unsigned long gs_base;
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unsigned long fs_base;
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};
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/* Execution mode, passed to the emulator. */
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#define X86EMUL_MODE_REAL 0 /* Real mode. */
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#define X86EMUL_MODE_PROT16 2 /* 16-bit protected mode. */
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#define X86EMUL_MODE_PROT32 4 /* 32-bit protected mode. */
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#define X86EMUL_MODE_PROT64 8 /* 64-bit (long) mode. */
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/* Host execution mode. */
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#if defined(__i386__)
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#define X86EMUL_MODE_HOST X86EMUL_MODE_PROT32
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#elif defined(CONFIG_X86_64)
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#define X86EMUL_MODE_HOST X86EMUL_MODE_PROT64
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#endif
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/*
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* x86_emulate_memop: Emulate an instruction that faulted attempting to
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* read/write a 'special' memory area.
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* Returns -1 on failure, 0 on success.
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*/
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int x86_emulate_memop(struct x86_emulate_ctxt *ctxt,
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struct x86_emulate_ops *ops);
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/*
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* Given the 'reg' portion of a ModRM byte, and a register block, return a
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* pointer into the block that addresses the relevant register.
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* @highbyte_regs specifies whether to decode AH,CH,DH,BH.
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*/
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void *decode_register(u8 modrm_reg, unsigned long *regs,
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int highbyte_regs);
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#endif /* __X86_EMULATE_H__ */
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