text: /******************************************************************************
   * 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 _ASM_X86_KVM_X86_EMULATE_H
  #define _ASM_X86_KVM_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, void *val,
  			unsigned int bytes, struct kvm_vcpu *vcpu);
  
  	/*
  	 * 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,
  			     void *val,
  			     unsigned int bytes,
  			     struct kvm_vcpu *vcpu);
  
  	/*
  	 * 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,
  			      const void *val,
  			      unsigned int bytes,
  			      struct kvm_vcpu *vcpu);
  
  	/*
  	 * 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,
  				const void *old,
  				const void *new,
  				unsigned int bytes,
  				struct kvm_vcpu *vcpu);
  
  };
  
  /* Type, address-of, and value of an instruction's operand. */
  struct operand {
  	enum { OP_REG, OP_MEM, OP_IMM, OP_NONE } type;
  	unsigned int bytes;
  	unsigned long val, orig_val, *ptr;
  };
  
  struct fetch_cache {
  	u8 data[15];
  	unsigned long start;
  	unsigned long end;
  };
  
  struct decode_cache {
  	u8 twobyte;
  	u8 b;
  	u8 lock_prefix;
  	u8 rep_prefix;
  	u8 op_bytes;
  	u8 ad_bytes;
  	u8 rex_prefix;
  	struct operand src;
  	struct operand src2;
  	struct operand dst;
  	bool has_seg_override;
  	u8 seg_override;
  	unsigned int d;
  	unsigned long regs[NR_VCPU_REGS];
  	unsigned long eip;
  	/* modrm */
  	u8 modrm;
  	u8 modrm_mod;
  	u8 modrm_reg;
  	u8 modrm_rm;
  	u8 use_modrm_ea;
  	bool rip_relative;
  	unsigned long modrm_ea;
  	void *modrm_ptr;
  	unsigned long modrm_val;
  	struct fetch_cache fetch;
  };
  
  #define X86_SHADOW_INT_MOV_SS  1
  #define X86_SHADOW_INT_STI     2
  
  struct x86_emulate_ctxt {
  	/* Register state before/after emulation. */
  	struct kvm_vcpu *vcpu;
  
  	unsigned long eflags;
  	/* Emulated execution mode, represented by an X86EMUL_MODE value. */
  	int mode;
  	u32 cs_base;
  
  	/* interruptibility state, as a result of execution of STI or MOV SS */
  	int interruptibility;
  
  	/* decode cache */
  	struct decode_cache decode;
  };
  
  /* Repeat String Operation Prefix */
  #define REPE_PREFIX	1
  #define REPNE_PREFIX	2
  
  /* 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(CONFIG_X86_32)
  #define X86EMUL_MODE_HOST X86EMUL_MODE_PROT32
  #elif defined(CONFIG_X86_64)
  #define X86EMUL_MODE_HOST X86EMUL_MODE_PROT64
  #endif
  
  int x86_decode_insn(struct x86_emulate_ctxt *ctxt,
  		    struct x86_emulate_ops *ops);
  int x86_emulate_insn(struct x86_emulate_ctxt *ctxt,
  		     struct x86_emulate_ops *ops);
  
  #endif /* _ASM_X86_KVM_X86_EMULATE_H */
  