README-instrumentation

To  use instrumentation features in bochs, you must compile in support for it.
You  should  build a custom instrumentation library in a separate directory in
the  "instrument/"  directory. To tell configure which instrumentation library
you  want  to  use,  use  the  "--enable-instrumentation"  option. The default
library consists of a set of stubs, and the following are equivalent:

  ./configure [...] --enable-instrumentation
  ./configure [...] --enable-instrumentation="instrument/stubs"

You  could  make  a  separate  directory with your custom library, for example
"instrument/myinstrument",   copy   the  contents  of  the  "instrument/stubs"
directory to it, then customize it. Use:

 ./configure [...] --enable-instrumentation="instrument/myinstrument"

-----------------------------------------------------------------------------
BOCHS instrumentation callbacks

	void bx_instr_init(unsigned cpu);

The  callback  is  called each time, when Bochs initializes the CPU object. It
can  be  used for initialization of user's data, dynamic memory allocation and
etc.

	void bx_instr_exit(unsigned cpu);

The  callback is called each time, when Bochs destructs the CPU object. It can
be used for destruction of user's data, allocated by bx_instr_init callback.


	void bx_instr_reset(unsigned cpu);

The  callback  is called each time, when Bochs resets the CPU object. It would
be  executed  once  at the start of simulation and each time that user presses
RESET BUTTON on the simulator's control panel.


	void bx_instr_hlt(unsigned cpu);

The  callback  is called  each time,  when Bochs' emulated  CPU enters HALT or
SHUTDOWN state. 


	void bx_instr_mwait(unsigned cpu, bx_phy_address addr, unsigned len, Bit32u flags);

The callback is called each time, when Bochs' emulated CPU enters to the MWAIT
state.  The  callback  receives  monitored  memory  range and MWAIT flags as a
parameters.


	void bx_instr_new_instruction(unsigned cpu);

The  callback  is  called  each  time,  when Bochs completes (commits) already
finished instruction and starts a new one.


	void bx_instr_cnear_branch_taken(unsigned cpu, bx_address new_eip);

The  callback  is  called  each time, when currently executed instruction is a
conditional near branch and it is taken.


	void bx_instr_cnear_branch_not_taken(unsigned cpu);

The  callback  is  called  each time, when currently executed instruction is a
conditional near branch and it is not taken.


	void bx_instr_ucnear_branch(unsigned cpu, unsigned what, bx_address new_eip);

The  callback  is  called each time, when currently executed instruction is an
unconditional near branch (always taken).


	void bx_instr_far_branch(unsigned cpu, unsigned what, Bit16u new_cs, bx_address new_eip);

The  callback  is  called each time, when currently executed instruction is an
unconditional far branch (always taken).


	void bx_instr_opcode(unsigned cpu, const Bit8u *opcode, unsigned len, bx_bool is32, bx_bool is64);

The  callback  is  called  each  time,  when  Bochs  starts  to  decode  a new
instruction.  Through  this callback function Bochs could provide an opcode of
the instruction, opcode length and an execution mode (16/32/64).

Currently the callback is not supported when trace-cache optimization feature
is enabled.


	void bx_instr_fetch_decode_completed(unsigned cpu, bxInstruction_c *i);

The  callback  is  called  each  time,  when  Bochs  finishes  decoding of new
instruction.  Through  this  callback  function  Bochs  could provide decoding
information  of the instruction. The bxInstruction_c argument of the callbacks
it  is  a  Bochs internal structure that holds all necessary information about
currently executed instruction, such as sib/modrm bytes, execution pointer and
etc.

	void bx_instr_prefix(unsigned cpu, Bit8u prefix);

These  callback  functions  are called by Bochs decoding stage each time, when
any prefix byte was decoded.


	void bx_instr_interrupt(unsigned cpu, unsigned vector);

The  callback  is called each time, when Bochs simulator executes an interrupt
(software interrupt, hardware interrupt or an exception).


	void bx_instr_exception(unsigned cpu, unsigned vector);

The callback is called each time, when Bochs simulator executes an exception.


	void bx_instr_hwinterrupt(unsigned cpu, unsigned vector, Bit16u cs, bx_address eip);

The  callback  is  called  each time, when Bochs simulator executes a hardware
interrupt.


	void bx_instr_clflush(unsigned cpu, bx_address laddr, bx_phy_address paddr);

The callback is called each time the CLFLUSH instruction is executed.


	void bx_instr_tlb_cntrl(unsigned cpu, unsigned what, bx_phy_address new_cr3);
	void bx_instr_cache_cntrl(unsigned cpu, unsigned what);

The  callback  is  called each time, when Bochs simulator executes a cache/tlb
control instruction.

Possible instruction types, passed through bx_instr_tlb_cntrl:

	#define BX_INSTR_MOV_CR3      	10
	#define BX_INSTR_INVLPG       	11
	#define BX_INSTR_TASKSWITCH   	12

Possible instruction types, passed through bx_instr_cache_cntrl:

	#define BX_INSTR_INVD         	20
	#define BX_INSTR_WBINVD       	21


	void bx_instr_prefetch_hint(unsigned cpu, unsigned what, unsigned seg, bx_address offset);

The  callback  is  called  each time, when Bochs simulator executes a PREFETCH
instruction.

Possible PREFETCH types:

	#define BX_INSTR_PREFETCH_NTA 	00
	#define BX_INSTR_PREFETCH_T0  	01
	#define BX_INSTR_PREFETCH_T1  	02
	#define BX_INSTR_PREFETCH_T2  	03

The seg/offset arguments indicate the address of the requested prefetch.


        void bx_instr_wrmsr(unsigned cpu, unsigned msr, Bit64u value);

This callback is called each time when WRMSR instruction is executed.
MSR number and written value passed as parameters to the callback function.


	void bx_instr_repeat_iteration(unsigned cpu, bxInstruction_c *i);

The  callback  is  called  each time, when Bochs simulator starts a new repeat
iteration.


	void bx_instr_before_execution(unsigned cpu, bxInstruction_c *i);

The  callback  is  called  each time, when Bochs simulator starts a new
instruction execution. In case of repeat instruction the callback will
be called only once before the first iteration will be started. 


	void bx_instr_after_execution(unsigned cpu, bxInstruction_c *i);

The  callback  is  called  each time, when Bochs simulator finishes any
instruction execution. In case of repeat instruction the callback will
be called only once after all repeat iterations. 


	void bx_instr_lin_access(unsigned cpu, bx_address lin, bx_address phy, unsigned len, unsigned rw);

The  callback  is  called  each  time,  when Bochs simulator executes a linear
memory  access.  Note  that  no  page split accesses will be generated because
Bochs  splits  page split accesses to two different memory accesses during its
execution  flow.  The  callback  also  will not be generated in case of direct
physical memory access like in SMM, VMM or SVM modes.

Possible access types are: BX_READ, BX_WRITE and BX_RW. 

Currently  the  callback is not supported when repeat-speedups optimization is
enabled.


	void bx_instr_mem_data_access(unsigned cpu, unsigned seg, bx_address offset, unsigned len, unsigned rw);

The  callback is called each time, when Bochs simulator executes segment based
linear memory access. In contrast to previous  callback it will be called even
if memory access fails  because of  any reason (for example segment protection
failure or page fault).

The callback will not be called for  system memory accesses like sys desriptor
tables reads/writes or new stack pushes during far call or exception.


	void bx_instr_phy_read(unsigned cpu, bx_address addr, unsigned len);
	void bx_instr_phy_write(unsigned cpu, bx_address addr, unsigned len);

These callback functions are the feedback from external memory system.


	void bx_instr_inp(Bit16u addr, unsigned len);
	void bx_instr_outp(Bit16u addr, unsigned len);
	void bx_instr_inp2(Bit16u addr, unsigned len, unsigned val);
	void bx_instr_outp2(Bit16u addr, unsigned len, unsigned val);

These callback functions are a feedback from various system devices.

-----------------------------------------------------------------------------
Known problems:

1. BX_INSTR_LIN_ACCESS doesn't work when repeat-speedups feature is enabled.

2. BX_INSTR_MEM_DATA doesn't work when repeat-speedups feature is enabled.

3. BX_INSTR_OPCODE doesn't work with trace cache optimization enabled

Feature requests:

1. BX_INSTR_CNEAR_BRANCH_NOT_TAKEN callback should have an additional 
   'not taken' new_EIP parameter.

2. BX_INSTR_SMI, BX_INSTR_NMI, BX_INSTR_SIPI and other external events
   callbacks

3.

While using Bochs as a reference model for simulations, the simulator needs
information about what loads/stores are taking place with each instruction.
Presumably,  that  is  what  the BX_INSTR_MEM_DATA() instrumentation macros
cover (which is the place where our simulator hooks up).

The RETnear_xxx() functions call access_linear() directly, rather than call
read_virtual_xxx()  functions. This is a problem for code making use of the
BX_INSTR_MEM_DATA()   hook  because  it  does  not  get  called  for  these
instructions.  Should  this  be  changed along with some other instructions
that exhibit this?
							Brian Slechta
