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/******************************************************************************
* x86_emulate.h
*
* Generic x86 (32-bit and 64-bit) instruction decoder and emulator.
*
* Copyright (c) 2005 Keir Fraser
*
* From: xen-unstable 10676:af9809f51f81a3c43f276f00c81a52ef558afda4
*/
#ifndef __X86_EMULATE_H__
#define __X86_EMULATE_H__
struct x86_emulate_ctxt;
/*
* x86_emulate_ops:
*
* These operations represent the instruction emulator's interface to memory.
* There are two categories of operation: those that act on ordinary memory
* regions (*_std), and those that act on memory regions known to require
* special treatment or emulation (*_emulated).
*
* The emulator assumes that an instruction accesses only one 'emulated memory'
* location, that this location is the given linear faulting address (cr2), and
* that this is one of the instruction's data operands. Instruction fetches and
* stack operations are assumed never to access emulated memory. The emulator
* automatically deduces which operand of a string-move operation is accessing
* emulated memory, and assumes that the other operand accesses normal memory.
*
* NOTES:
* 1. The emulator isn't very smart about emulated vs. standard memory.
* 'Emulated memory' access addresses should be checked for sanity.
* 'Normal memory' accesses may fault, and the caller must arrange to
* detect and handle reentrancy into the emulator via recursive faults.
* Accesses may be unaligned and may cross page boundaries.
* 2. If the access fails (cannot emulate, or a standard access faults) then
* it is up to the memop to propagate the fault to the guest VM via
* some out-of-band mechanism, unknown to the emulator. The memop signals
* failure by returning X86EMUL_PROPAGATE_FAULT to the emulator, which will
* then immediately bail.
* 3. Valid access sizes are 1, 2, 4 and 8 bytes. On x86/32 systems only
* cmpxchg8b_emulated need support 8-byte accesses.
* 4. The emulator cannot handle 64-bit mode emulation on an x86/32 system.
*/
/* Access completed successfully: continue emulation as normal. */
#define X86EMUL_CONTINUE 0
/* Access is unhandleable: bail from emulation and return error to caller. */
#define X86EMUL_UNHANDLEABLE 1
/* Terminate emulation but return success to the caller. */
#define X86EMUL_PROPAGATE_FAULT 2 /* propagate a generated fault to guest */
#define X86EMUL_RETRY_INSTR 2 /* retry the instruction for some reason */
#define X86EMUL_CMPXCHG_FAILED 2 /* cmpxchg did not see expected value */
struct x86_emulate_ops {
/*
* read_std: Read bytes of standard (non-emulated/special) memory.
* Used for instruction fetch, stack operations, and others.
* @addr: [IN ] Linear address from which to read.
* @val: [OUT] Value read from memory, zero-extended to 'u_long'.
* @bytes: [IN ] Number of bytes to read from memory.
*/
int (*read_std)(unsigned long addr,
unsigned long *val,
unsigned int bytes, struct x86_emulate_ctxt * ctxt);
/*
* write_std: Write bytes of standard (non-emulated/special) memory.
* Used for stack operations, and others.
* @addr: [IN ] Linear address to which to write.
* @val: [IN ] Value to write to memory (low-order bytes used as
* required).
* @bytes: [IN ] Number of bytes to write to memory.
*/
int (*write_std)(unsigned long addr,
unsigned long val,
unsigned int bytes, struct x86_emulate_ctxt * ctxt);
/*
* read_emulated: Read bytes from emulated/special memory area.
* @addr: [IN ] Linear address from which to read.
* @val: [OUT] Value read from memory, zero-extended to 'u_long'.
* @bytes: [IN ] Number of bytes to read from memory.
*/
int (*read_emulated) (unsigned long addr,
unsigned long *val,
unsigned int bytes,
struct x86_emulate_ctxt * ctxt);
/*
* write_emulated: Read bytes from emulated/special memory area.
* @addr: [IN ] Linear address to which to write.
* @val: [IN ] Value to write to memory (low-order bytes used as
* required).
* @bytes: [IN ] Number of bytes to write to memory.
*/
int (*write_emulated) (unsigned long addr,
unsigned long val,
unsigned int bytes,
struct x86_emulate_ctxt * ctxt);
/*
* cmpxchg_emulated: Emulate an atomic (LOCKed) CMPXCHG operation on an
* emulated/special memory area.
* @addr: [IN ] Linear address to access.
* @old: [IN ] Value expected to be current at @addr.
* @new: [IN ] Value to write to @addr.
* @bytes: [IN ] Number of bytes to access using CMPXCHG.
*/
int (*cmpxchg_emulated) (unsigned long addr,
unsigned long old,
unsigned long new,
unsigned int bytes,
struct x86_emulate_ctxt * ctxt);
/*
* cmpxchg8b_emulated: Emulate an atomic (LOCKed) CMPXCHG8B operation on an
* emulated/special memory area.
* @addr: [IN ] Linear address to access.
* @old: [IN ] Value expected to be current at @addr.
* @new: [IN ] Value to write to @addr.
* NOTES:
* 1. This function is only ever called when emulating a real CMPXCHG8B.
* 2. This function is *never* called on x86/64 systems.
* 2. Not defining this function (i.e., specifying NULL) is equivalent
* to defining a function that always returns X86EMUL_UNHANDLEABLE.
*/
int (*cmpxchg8b_emulated) (unsigned long addr,
unsigned long old_lo,
unsigned long old_hi,
unsigned long new_lo,
unsigned long new_hi,
struct x86_emulate_ctxt * ctxt);
};
struct cpu_user_regs;
struct x86_emulate_ctxt {
/* Register state before/after emulation. */
struct kvm_vcpu *vcpu;
/* Linear faulting address (if emulating a page-faulting instruction). */
unsigned long eflags;
unsigned long cr2;
/* Emulated execution mode, represented by an X86EMUL_MODE value. */
int mode;
unsigned long cs_base;
unsigned long ds_base;
unsigned long es_base;
unsigned long ss_base;
unsigned long gs_base;
unsigned long fs_base;
};
/* Execution mode, passed to the emulator. */
#define X86EMUL_MODE_REAL 0 /* Real mode. */
#define X86EMUL_MODE_PROT16 2 /* 16-bit protected mode. */
#define X86EMUL_MODE_PROT32 4 /* 32-bit protected mode. */
#define X86EMUL_MODE_PROT64 8 /* 64-bit (long) mode. */
/* Host execution mode. */
#if defined(__i386__)
#define X86EMUL_MODE_HOST X86EMUL_MODE_PROT32
#elif defined(__x86_64__)
#define X86EMUL_MODE_HOST X86EMUL_MODE_PROT64
#endif
/*
* x86_emulate_memop: Emulate an instruction that faulted attempting to
* read/write a 'special' memory area.
* Returns -1 on failure, 0 on success.
*/
int x86_emulate_memop(struct x86_emulate_ctxt *ctxt,
struct x86_emulate_ops *ops);
/*
* Given the 'reg' portion of a ModRM byte, and a register block, return a
* pointer into the block that addresses the relevant register.
* @highbyte_regs specifies whether to decode AH,CH,DH,BH.
*/
void *decode_register(u8 modrm_reg, unsigned long *regs,
int highbyte_regs);
#endif /* __X86_EMULATE_H__ */
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