ghelpers.c

The Valgrind distribution has multiple tools. The most popular is the memory checking tool (called M

/*---------------------------------------------------------------*/
/*---                                                         ---*/
/*--- This file (guest-x86/ghelpers.c) is                     ---*/
/*--- Copyright (C) OpenWorks LLP.  All rights reserved.      ---*/
/*---                                                         ---*/
/*---------------------------------------------------------------*/

/*
   This file is part of LibVEX, a library for dynamic binary
   instrumentation and translation.

   Copyright (C) 2004-2006 OpenWorks LLP.  All rights reserved.

   This library is made available under a dual licensing scheme.

   If you link LibVEX against other code all of which is itself
   licensed under the GNU General Public License, version 2 dated June
   1991 ("GPL v2"), then you may use LibVEX under the terms of the GPL
   v2, as appearing in the file LICENSE.GPL.  If the file LICENSE.GPL
   is missing, you can obtain a copy of the GPL v2 from the Free
   Software Foundation Inc., 51 Franklin St, Fifth Floor, Boston, MA
   02110-1301, USA.

   For any other uses of LibVEX, you must first obtain a commercial
   license from OpenWorks LLP.  Please contact [e-mail]
   for information about commercial licensing.

   This software is provided by OpenWorks LLP "as is" and any express
   or implied warranties, including, but not limited to, the implied
   warranties of merchantability and fitness for a particular purpose
   are disclaimed.  In no event shall OpenWorks LLP be liable for any
   direct, indirect, incidental, special, exemplary, or consequential
   damages (including, but not limited to, procurement of substitute
   goods or services; loss of use, data, or profits; or business
   interruption) however caused and on any theory of liability,
   whether in contract, strict liability, or tort (including
   negligence or otherwise) arising in any way out of the use of this
   software, even if advised of the possibility of such damage.

   Neither the names of the U.S. Department of Energy nor the
   University of California nor the names of its contributors may be
   used to endorse or promote products derived from this software
   without prior written permission.
*/

#include "libvex_basictypes.h"
#include "libvex_emwarn.h"
#include "libvex_guest_x86.h"
#include "libvex_ir.h"
#include "libvex.h"

#include "main/vex_util.h"
#include "guest-generic/bb_to_IR.h"
#include "guest-x86/gdefs.h"
#include "guest-generic/g_generic_x87.h"


/* This file contains helper functions for x86 guest code.
   Calls to these functions are generated by the back end.
   These calls are of course in the host machine code and 
   this file will be compiled to host machine code, so that
   all makes sense.  

   Only change the signatures of these helper functions very
   carefully.  If you change the signature here, you'll have to change
   the parameters passed to it in the IR calls constructed by
   guest-x86/toIR.c.

   The convention used is that all functions called from generated
   code are named x86g_<something>, and any function whose name lacks
   that prefix is not called from generated code.  Note that some
   LibVEX_* functions can however be called by VEX's client, but that
   is not the same as calling them from VEX-generated code.
*/


/* Set to 1 to get detailed profiling info about use of the flag
   machinery. */
#define PROFILE_EFLAGS 0


/*---------------------------------------------------------------*/
/*--- %eflags run-time helpers.                               ---*/
/*---------------------------------------------------------------*/

static const UChar parity_table[256] = {
    X86G_CC_MASK_P, 0, 0, X86G_CC_MASK_P, 0, X86G_CC_MASK_P, X86G_CC_MASK_P, 0,
    0, X86G_CC_MASK_P, X86G_CC_MASK_P, 0, X86G_CC_MASK_P, 0, 0, X86G_CC_MASK_P,
    0, X86G_CC_MASK_P, X86G_CC_MASK_P, 0, X86G_CC_MASK_P, 0, 0, X86G_CC_MASK_P,
    X86G_CC_MASK_P, 0, 0, X86G_CC_MASK_P, 0, X86G_CC_MASK_P, X86G_CC_MASK_P, 0,
    0, X86G_CC_MASK_P, X86G_CC_MASK_P, 0, X86G_CC_MASK_P, 0, 0, X86G_CC_MASK_P,
    X86G_CC_MASK_P, 0, 0, X86G_CC_MASK_P, 0, X86G_CC_MASK_P, X86G_CC_MASK_P, 0,
    X86G_CC_MASK_P, 0, 0, X86G_CC_MASK_P, 0, X86G_CC_MASK_P, X86G_CC_MASK_P, 0,
    0, X86G_CC_MASK_P, X86G_CC_MASK_P, 0, X86G_CC_MASK_P, 0, 0, X86G_CC_MASK_P,
    0, X86G_CC_MASK_P, X86G_CC_MASK_P, 0, X86G_CC_MASK_P, 0, 0, X86G_CC_MASK_P,
    X86G_CC_MASK_P, 0, 0, X86G_CC_MASK_P, 0, X86G_CC_MASK_P, X86G_CC_MASK_P, 0,
    X86G_CC_MASK_P, 0, 0, X86G_CC_MASK_P, 0, X86G_CC_MASK_P, X86G_CC_MASK_P, 0,
    0, X86G_CC_MASK_P, X86G_CC_MASK_P, 0, X86G_CC_MASK_P, 0, 0, X86G_CC_MASK_P,
    X86G_CC_MASK_P, 0, 0, X86G_CC_MASK_P, 0, X86G_CC_MASK_P, X86G_CC_MASK_P, 0,
    0, X86G_CC_MASK_P, X86G_CC_MASK_P, 0, X86G_CC_MASK_P, 0, 0, X86G_CC_MASK_P,
    0, X86G_CC_MASK_P, X86G_CC_MASK_P, 0, X86G_CC_MASK_P, 0, 0, X86G_CC_MASK_P,
    X86G_CC_MASK_P, 0, 0, X86G_CC_MASK_P, 0, X86G_CC_MASK_P, X86G_CC_MASK_P, 0,
    0, X86G_CC_MASK_P, X86G_CC_MASK_P, 0, X86G_CC_MASK_P, 0, 0, X86G_CC_MASK_P,
    X86G_CC_MASK_P, 0, 0, X86G_CC_MASK_P, 0, X86G_CC_MASK_P, X86G_CC_MASK_P, 0,
    X86G_CC_MASK_P, 0, 0, X86G_CC_MASK_P, 0, X86G_CC_MASK_P, X86G_CC_MASK_P, 0,
    0, X86G_CC_MASK_P, X86G_CC_MASK_P, 0, X86G_CC_MASK_P, 0, 0, X86G_CC_MASK_P,
    X86G_CC_MASK_P, 0, 0, X86G_CC_MASK_P, 0, X86G_CC_MASK_P, X86G_CC_MASK_P, 0,
    0, X86G_CC_MASK_P, X86G_CC_MASK_P, 0, X86G_CC_MASK_P, 0, 0, X86G_CC_MASK_P,
    0, X86G_CC_MASK_P, X86G_CC_MASK_P, 0, X86G_CC_MASK_P, 0, 0, X86G_CC_MASK_P,
    X86G_CC_MASK_P, 0, 0, X86G_CC_MASK_P, 0, X86G_CC_MASK_P, X86G_CC_MASK_P, 0,
    X86G_CC_MASK_P, 0, 0, X86G_CC_MASK_P, 0, X86G_CC_MASK_P, X86G_CC_MASK_P, 0,
    0, X86G_CC_MASK_P, X86G_CC_MASK_P, 0, X86G_CC_MASK_P, 0, 0, X86G_CC_MASK_P,
    0, X86G_CC_MASK_P, X86G_CC_MASK_P, 0, X86G_CC_MASK_P, 0, 0, X86G_CC_MASK_P,
    X86G_CC_MASK_P, 0, 0, X86G_CC_MASK_P, 0, X86G_CC_MASK_P, X86G_CC_MASK_P, 0,
    0, X86G_CC_MASK_P, X86G_CC_MASK_P, 0, X86G_CC_MASK_P, 0, 0, X86G_CC_MASK_P,
    X86G_CC_MASK_P, 0, 0, X86G_CC_MASK_P, 0, X86G_CC_MASK_P, X86G_CC_MASK_P, 0,
    X86G_CC_MASK_P, 0, 0, X86G_CC_MASK_P, 0, X86G_CC_MASK_P, X86G_CC_MASK_P, 0,
    0, X86G_CC_MASK_P, X86G_CC_MASK_P, 0, X86G_CC_MASK_P, 0, 0, X86G_CC_MASK_P,
};

/* generalised left-shifter */
inline static Int lshift ( Int x, Int n )
{
   if (n >= 0)
      return x << n;
   else
      return x >> (-n);
}

/* identity on ULong */
static inline ULong idULong ( ULong x )
{
   return x;
}


#define PREAMBLE(__data_bits)					\
   /* const */ UInt DATA_MASK 					\
      = __data_bits==8 ? 0xFF 					\
                       : (__data_bits==16 ? 0xFFFF 		\
                                          : 0xFFFFFFFF); 	\
   /* const */ UInt SIGN_MASK = 1 << (__data_bits - 1);		\
   /* const */ UInt CC_DEP1 = cc_dep1_formal;			\
   /* const */ UInt CC_DEP2 = cc_dep2_formal;			\
   /* const */ UInt CC_NDEP = cc_ndep_formal;			\
   /* Four bogus assignments, which hopefully gcc can     */	\
   /* optimise away, and which stop it complaining about  */	\
   /* unused variables.                                   */	\
   SIGN_MASK = SIGN_MASK;					\
   DATA_MASK = DATA_MASK;					\
   CC_DEP2 = CC_DEP2;						\
   CC_NDEP = CC_NDEP;


/*-------------------------------------------------------------*/

#define ACTIONS_ADD(DATA_BITS,DATA_UTYPE)			\
{								\
   PREAMBLE(DATA_BITS);						\
   { Int cf, pf, af, zf, sf, of;				\
     Int argL, argR, res;					\
     argL = CC_DEP1;						\
     argR = CC_DEP2;						\
     res  = argL + argR;					\
     cf = (DATA_UTYPE)res < (DATA_UTYPE)argL;			\
     pf = parity_table[(UChar)res];				\
     af = (res ^ argL ^ argR) & 0x10;				\
     zf = ((DATA_UTYPE)res == 0) << 6;				\
     sf = lshift(res, 8 - DATA_BITS) & 0x80;			\
     of = lshift((argL ^ argR ^ -1) & (argL ^ res), 		\
                 12 - DATA_BITS) & X86G_CC_MASK_O;		\
     return cf | pf | af | zf | sf | of;			\
   }								\
}

/*-------------------------------------------------------------*/

#define ACTIONS_SUB(DATA_BITS,DATA_UTYPE)			\
{								\
   PREAMBLE(DATA_BITS);						\
   { Int cf, pf, af, zf, sf, of;				\
     Int argL, argR, res;					\
     argL = CC_DEP1;						\
     argR = CC_DEP2;						\
     res  = argL - argR;					\
     cf = (DATA_UTYPE)argL < (DATA_UTYPE)argR;			\
     pf = parity_table[(UChar)res];				\
     af = (res ^ argL ^ argR) & 0x10;				\
     zf = ((DATA_UTYPE)res == 0) << 6;				\
     sf = lshift(res, 8 - DATA_BITS) & 0x80;			\
     of = lshift((argL ^ argR) & (argL ^ res),	 		\
                 12 - DATA_BITS) & X86G_CC_MASK_O; 		\
     return cf | pf | af | zf | sf | of;			\
   }								\
}

/*-------------------------------------------------------------*/

#define ACTIONS_ADC(DATA_BITS,DATA_UTYPE)			\
{								\
   PREAMBLE(DATA_BITS);						\
   { Int cf, pf, af, zf, sf, of;				\
     Int argL, argR, oldC, res;		       			\
     oldC = CC_NDEP & X86G_CC_MASK_C;				\
     argL = CC_DEP1;						\
     argR = CC_DEP2 ^ oldC;	       				\
     res  = (argL + argR) + oldC;				\
     if (oldC)							\
        cf = (DATA_UTYPE)res <= (DATA_UTYPE)argL;		\
     else							\
        cf = (DATA_UTYPE)res < (DATA_UTYPE)argL;		\
     pf = parity_table[(UChar)res];				\
     af = (res ^ argL ^ argR) & 0x10;				\
     zf = ((DATA_UTYPE)res == 0) << 6;				\
     sf = lshift(res, 8 - DATA_BITS) & 0x80;			\
     of = lshift((argL ^ argR ^ -1) & (argL ^ res), 		\
                  12 - DATA_BITS) & X86G_CC_MASK_O;		\
     return cf | pf | af | zf | sf | of;			\
   }								\
}

/*-------------------------------------------------------------*/

#define ACTIONS_SBB(DATA_BITS,DATA_UTYPE)			\
{								\
   PREAMBLE(DATA_BITS);						\
   { Int cf, pf, af, zf, sf, of;				\
     Int argL, argR, oldC, res;		       			\
     oldC = CC_NDEP & X86G_CC_MASK_C;				\
     argL = CC_DEP1;						\
     argR = CC_DEP2 ^ oldC;	       				\
     res  = (argL - argR) - oldC;				\
     if (oldC)							\
        cf = (DATA_UTYPE)argL <= (DATA_UTYPE)argR;		\
     else							\
        cf = (DATA_UTYPE)argL < (DATA_UTYPE)argR;		\
     pf = parity_table[(UChar)res];				\
     af = (res ^ argL ^ argR) & 0x10;				\
     zf = ((DATA_UTYPE)res == 0) << 6;				\
     sf = lshift(res, 8 - DATA_BITS) & 0x80;			\
     of = lshift((argL ^ argR) & (argL ^ res), 			\
                 12 - DATA_BITS) & X86G_CC_MASK_O;		\
     return cf | pf | af | zf | sf | of;			\
   }								\
}

/*-------------------------------------------------------------*/

#define ACTIONS_LOGIC(DATA_BITS,DATA_UTYPE)			\
{								\
   PREAMBLE(DATA_BITS);						\
   { Int cf, pf, af, zf, sf, of;				\
     cf = 0;							\
     pf = parity_table[(UChar)CC_DEP1];				\
     af = 0;							\
     zf = ((DATA_UTYPE)CC_DEP1 == 0) << 6;			\
     sf = lshift(CC_DEP1, 8 - DATA_BITS) & 0x80;		\
     of = 0;							\
     return cf | pf | af | zf | sf | of;			\
   }								\
}

/*-------------------------------------------------------------*/

#define ACTIONS_INC(DATA_BITS,DATA_UTYPE)			\
{								\
   PREAMBLE(DATA_BITS);						\
   { Int cf, pf, af, zf, sf, of;				\
     Int argL, argR, res;					\
     res  = CC_DEP1;						\
     argL = res - 1;						\
     argR = 1;							\
     cf = CC_NDEP & X86G_CC_MASK_C;				\
     pf = parity_table[(UChar)res];				\
     af = (res ^ argL ^ argR) & 0x10;				\
     zf = ((DATA_UTYPE)res == 0) << 6;				\
     sf = lshift(res, 8 - DATA_BITS) & 0x80;			\
     of = ((res & DATA_MASK) == SIGN_MASK) << 11;		\
     return cf | pf | af | zf | sf | of;			\
   }								\
}

/*-------------------------------------------------------------*/

#define ACTIONS_DEC(DATA_BITS,DATA_UTYPE)			\
{								\
   PREAMBLE(DATA_BITS);						\
   { Int cf, pf, af, zf, sf, of;				\
     Int argL, argR, res;					\
     res  = CC_DEP1;						\
     argL = res + 1;						\
     argR = 1;							\
     cf = CC_NDEP & X86G_CC_MASK_C;				\
     pf = parity_table[(UChar)res];				\
     af = (res ^ argL ^ argR) & 0x10;				\
     zf = ((DATA_UTYPE)res == 0) << 6;				\
     sf = lshift(res, 8 - DATA_BITS) & 0x80;			\
     of = ((res & DATA_MASK) 					\
          == ((UInt)SIGN_MASK - 1)) << 11;			\
     return cf | pf | af | zf | sf | of;			\
   }								\
}

/*-------------------------------------------------------------*/

#define ACTIONS_SHL(DATA_BITS,DATA_UTYPE)			\
{								\
   PREAMBLE(DATA_BITS);						\
   { Int cf, pf, af, zf, sf, of;				\
     cf = (CC_DEP2 >> (DATA_BITS - 1)) & X86G_CC_MASK_C;	\
     pf = parity_table[(UChar)CC_DEP1];				\
     af = 0; /* undefined */					\
     zf = ((DATA_UTYPE)CC_DEP1 == 0) << 6;			\
     sf = lshift(CC_DEP1, 8 - DATA_BITS) & 0x80;		\
     /* of is defined if shift count == 1 */			\
     of = lshift(CC_DEP2 ^ CC_DEP1, 12 - DATA_BITS) 		\
          & X86G_CC_MASK_O;					\
     return cf | pf | af | zf | sf | of;			\
   }								\
}

/*-------------------------------------------------------------*/

#define ACTIONS_SHR(DATA_BITS,DATA_UTYPE)			\
{								\
   PREAMBLE(DATA_BITS);  					\
   { Int cf, pf, af, zf, sf, of;				\
     cf = CC_DEP2 & 1;						\
     pf = parity_table[(UChar)CC_DEP1];				\
     af = 0; /* undefined */					\
     zf = ((DATA_UTYPE)CC_DEP1 == 0) << 6;			\
     sf = lshift(CC_DEP1, 8 - DATA_BITS) & 0x80;		\
     /* of is defined if shift count == 1 */			\
     of = lshift(CC_DEP2 ^ CC_DEP1, 12 - DATA_BITS)		\
          & X86G_CC_MASK_O;					\
     return cf | pf | af | zf | sf | of;			\
   }								\
}

/*-------------------------------------------------------------*/

/* ROL: cf' = lsb(result).  of' = msb(result) ^ lsb(result). */
/* DEP1 = result, NDEP = old flags */
#define ACTIONS_ROL(DATA_BITS,DATA_UTYPE)			\
{								\
   PREAMBLE(DATA_BITS);						\
   { Int fl 							\
        = (CC_NDEP & ~(X86G_CC_MASK_O | X86G_CC_MASK_C))	\
          | (X86G_CC_MASK_C & CC_DEP1)				\
          | (X86G_CC_MASK_O & (lshift(CC_DEP1,  		\
                                      11-(DATA_BITS-1)) 	\
                     ^ lshift(CC_DEP1, 11)));			\
     return fl;							\
   }								\
}

/*-------------------------------------------------------------*/

/* ROR: cf' = msb(result).  of' = msb(result) ^ msb-1(result). */
/* DEP1 = result, NDEP = old flags */
#define ACTIONS_ROR(DATA_BITS,DATA_UTYPE)			\
{								\
   PREAMBLE(DATA_BITS);						\
   { Int fl 							\
        = (CC_NDEP & ~(X86G_CC_MASK_O | X86G_CC_MASK_C))	\
          | (X86G_CC_MASK_C & (CC_DEP1 >> (DATA_BITS-1)))	\
          | (X86G_CC_MASK_O & (lshift(CC_DEP1, 			\
                                      11-(DATA_BITS-1)) 	\
                     ^ lshift(CC_DEP1, 11-(DATA_BITS-1)+1)));	\
     return fl;							\
   }								\
}

/*-------------------------------------------------------------*/

#define ACTIONS_UMUL(DATA_BITS, DATA_UTYPE,  NARROWtoU,         \
                                DATA_U2TYPE, NARROWto2U)        \
{                                                               \
   PREAMBLE(DATA_BITS);                                         \