src/arch/x86/utility.hh

   1 /*
   2  * Copyright (c) 2007 The Hewlett-Packard Development Company
   3  * All rights reserved.
   4  *
   5  * The license below extends only to copyright in the software and shall
   6  * not be construed as granting a license to any other intellectual
   7  * property including but not limited to intellectual property relating
   8  * to a hardware implementation of the functionality of the software
   9  * licensed hereunder.  You may use the software subject to the license
  10  * terms below provided that you ensure that this notice is replicated
  11  * unmodified and in its entirety in all distributions of the software,
  12  * modified or unmodified, in source code or in binary form.
  13  *
  14  * Redistribution and use in source and binary forms, with or without
  15  * modification, are permitted provided that the following conditions are
  16  * met: redistributions of source code must retain the above copyright
  17  * notice, this list of conditions and the following disclaimer;
  18  * redistributions in binary form must reproduce the above copyright
  19  * notice, this list of conditions and the following disclaimer in the
  20  * documentation and/or other materials provided with the distribution;
  21  * neither the name of the copyright holders nor the names of its
  22  * contributors may be used to endorse or promote products derived from
  23  * this software without specific prior written permission.
  24  *
  25  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  26  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  27  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  28  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  29  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  30  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  31  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  32  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  33  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  34  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  35  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  36  *
  37  * Authors: Gabe Black
  38  */
  39
  40 #ifndef __ARCH_X86_UTILITY_HH__
  41 #define __ARCH_X86_UTILITY_HH__
  42
  43 #include "cpu/static_inst.hh"
  44 #include "cpu/thread_context.hh"
  45 #include "sim/full_system.hh"
  46
  47 namespace X86ISA
  48 {
  49
  50     inline PCState
  51     buildRetPC(const PCState &curPC, const PCState &callPC)
  52     {
  53         PCState retPC = callPC;
  54         retPC.uEnd();
  55         return retPC;
  56     }
  57
  58     uint64_t
  59     getArgument(ThreadContext *tc, int &number, uint16_t size, bool fp);
  60
  61     static inline bool
  62     inUserMode(ThreadContext *tc)
  63     {
  64         if (!FullSystem) {
  65             return true;
  66         } else {
  67             HandyM5Reg m5reg = tc->readMiscRegNoEffect(MISCREG_M5_REG);
  68             return m5reg.cpl == 3;
  69         }
  70     }
  71
  72     /**
  73      * Function to insure ISA semantics about 0 registers.
  74      * @param tc The thread context.
  75      */
  76     template <class TC>
  77     void zeroRegisters(TC *tc);
  78
  79     void initCPU(ThreadContext *tc, int cpuId);
  80
  81     void startupCPU(ThreadContext *tc, int cpuId);
  82
  83     void copyRegs(ThreadContext *src, ThreadContext *dest);
  84
  85     void copyMiscRegs(ThreadContext *src, ThreadContext *dest);
  86
  87     void skipFunction(ThreadContext *tc);
  88
  89     inline void
  90     advancePC(PCState &pc, const StaticInstPtr &inst)
  91     {
  92         inst->advancePC(pc);
  93     }
  94
  95     inline uint64_t
  96     getExecutingAsid(ThreadContext *tc)
  97     {
  98         return 0;
  99     }
 100
 101
 102     /**
 103      * Reconstruct the rflags register from the internal gem5 register
 104      * state.
 105      *
 106      * gem5 stores rflags in several different registers to avoid
 107      * pipeline dependencies. In order to get the true rflags value,
 108      * we can't simply read the value of MISCREG_RFLAGS. Instead, we
 109      * need to read out various state from microcode registers and
 110      * merge that with MISCREG_RFLAGS.
 111      *
 112      * @param tc Thread context to read rflags from.
 113      * @return rflags as seen by the guest.
 114      */
 115     uint64_t getRFlags(ThreadContext *tc);
 116
 117     /**
 118      * Set update the rflags register and internal gem5 state.
 119      *
 120      * @note This function does not update MISCREG_M5_REG. You might
 121      * need to update this register by writing anything to
 122      * MISCREG_M5_REG with side-effects.
 123      *
 124      * @see X86ISA::getRFlags()
 125      *
 126      * @param tc Thread context to update
 127      * @param val New rflags value to store in TC
 128      */
 129     void setRFlags(ThreadContext *tc, uint64_t val);
 130
 131     /**
 132      * Extract the bit string representing a double value.
 133      */
 134     inline uint64_t getDoubleBits(double val) {
 135         return *(uint64_t *)(&val);
 136     }
 137
 138     /**
 139      * Convert an x87 tag word to abridged tag format.
 140      *
 141      * Convert from the x87 tag representation to the tag abridged
 142      * representation used in the FXSAVE area. The classic format uses
 143      * 2 bits per stack position to indicate if a position is valid,
 144      * zero, special, or empty. The abridged format only stores
 145      * whether a position is empty or not.
 146      *
 147      * @param ftw Tag word in classic x87 format.
 148      * @return Tag word in the abridged format.
 149      */
 150     uint8_t convX87TagsToXTags(uint16_t ftw);
 151
 152     /**
 153      * Convert an x87 xtag word to normal tags format.
 154      *
 155      * Convert from the abridged x87 tag representation used in the
 156      * FXSAVE area to a full x87 tag. The classic format uses 2 bits
 157      * per stack position to indicate if a position is valid, zero,
 158      * special, or empty. The abridged format only stores whether a
 159      * position is empty or not.
 160      *
 161      * @todo Reconstruct the correct state of stack positions instead
 162      * of just valid/invalid.
 163      *
 164      * @param ftwx Tag word in the abridged format.
 165      * @return Tag word in classic x87 format.
 166      */
 167     uint16_t convX87XTagsToTags(uint8_t ftwx);
 168
 169     /**
 170      * Generate and updated x87 tag register after a push/pop
 171      * operation.
 172      *
 173      * @note There is currently no support for setting other tags than
 174      * valid and invalid. A real x87 will set the tag value to zero or
 175      * special for some special floating point values.
 176      *
 177      * @param ftw Current value of the FTW register.
 178      * @param top Current x87 TOP value.
 179      * @param spm Stack displacement.
 180      * @return New value of the FTW register.
 181      */
 182     uint16_t genX87Tags(uint16_t ftw, uint8_t top, int8_t spm);
 183
 184     /**
 185      * Load an 80-bit float from memory and convert it to double.
 186      *
 187      * @param mem Pointer to an 80-bit float.
 188      * @return double representation of the 80-bit float.
 189      */
 190     double loadFloat80(const void *mem);
 191
 192     /**
 193      * Convert and store a double as an 80-bit float.
 194      *
 195      * @param mem Pointer to destination for the 80-bit float.
 196      * @param value Double precision float to store.
 197      */
 198     void storeFloat80(void *mem, double value);
 199 }
 200
 201 #endif // __ARCH_X86_UTILITY_HH__