/*
 * Copyright (c) 2009 The Regents of The University of Michigan
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met: redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer;
 * redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution;
 * neither the name of the copyright holders nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "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 THE COPYRIGHT
 * OWNER OR CONTRIBUTORS 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.
 */

#include "arch/x86/isa.hh"

#include "arch/x86/decoder.hh"
#include "arch/x86/mmu.hh"
#include "arch/x86/regs/ccr.hh"
#include "arch/x86/regs/int.hh"
#include "arch/x86/regs/misc.hh"
#include "base/compiler.hh"
#include "cpu/base.hh"
#include "cpu/thread_context.hh"
#include "debug/CCRegs.hh"
#include "debug/FloatRegs.hh"
#include "debug/IntRegs.hh"
#include "debug/MiscRegs.hh"
#include "params/X86ISA.hh"
#include "sim/serialize.hh"

namespace gem5
{

namespace X86ISA
{

void
ISA::updateHandyM5Reg(Efer efer, CR0 cr0,
                      SegAttr csAttr, SegAttr ssAttr, RFLAGS rflags)
{
    HandyM5Reg m5reg = 0;
    if (efer.lma) {
        m5reg.mode = LongMode;
        if (csAttr.longMode)
            m5reg.submode = SixtyFourBitMode;
        else
            m5reg.submode = CompatabilityMode;
    } else {
        m5reg.mode = LegacyMode;
        if (cr0.pe) {
            if (rflags.vm)
                m5reg.submode = Virtual8086Mode;
            else
                m5reg.submode = ProtectedMode;
        } else {
            m5reg.submode = RealMode;
        }
    }
    m5reg.cpl = csAttr.dpl;
    m5reg.paging = cr0.pg;
    m5reg.prot = cr0.pe;

    // Compute the default and alternate operand size.
    if (m5reg.submode == SixtyFourBitMode || csAttr.defaultSize) {
        m5reg.defOp = 2;
        m5reg.altOp = 1;
    } else {
        m5reg.defOp = 1;
        m5reg.altOp = 2;
    }

    // Compute the default and alternate address size.
    if (m5reg.submode == SixtyFourBitMode) {
        m5reg.defAddr = 3;
        m5reg.altAddr = 2;
    } else if (csAttr.defaultSize) {
        m5reg.defAddr = 2;
        m5reg.altAddr = 1;
    } else {
        m5reg.defAddr = 1;
        m5reg.altAddr = 2;
    }

    // Compute the stack size
    if (m5reg.submode == SixtyFourBitMode) {
        m5reg.stack = 3;
    } else if (ssAttr.defaultSize) {
        m5reg.stack = 2;
    } else {
        m5reg.stack = 1;
    }

    regVal[MISCREG_M5_REG] = m5reg;
    if (tc)
        tc->getDecoderPtr()->as<Decoder>().setM5Reg(m5reg);
}

void
ISA::clear()
{
    // Blank everything. 0 might not be an appropriate value for some things,
    // but it is for most.
    memset(regVal, 0, NUM_MISCREGS * sizeof(RegVal));

    // If some state should be non-zero after a reset, set those values here.
    regVal[MISCREG_CR0] = 0x0000000060000010ULL;

    regVal[MISCREG_MTRRCAP] = 0x0508;

    regVal[MISCREG_MCG_CAP] = 0x104;

    regVal[MISCREG_PAT] = 0x0007040600070406ULL;

    regVal[MISCREG_SYSCFG] = 0x20601;

    regVal[MISCREG_TOP_MEM] = 0x4000000;

    regVal[MISCREG_DR6] = (mask(8) << 4) | (mask(16) << 16);
    regVal[MISCREG_DR7] = 1 << 10;

    LocalApicBase lApicBase = 0;
    lApicBase.base = 0xFEE00000 >> 12;
    lApicBase.enable = 1;
    // The "bsp" bit will be set when this register is read, since then we'll
    // have a ThreadContext to check the contextId from.
    regVal[MISCREG_APIC_BASE] = lApicBase;
}

ISA::ISA(const X86ISAParams &p) : BaseISA(p), vendorString(p.vendor_string)
{
    fatal_if(vendorString.size() != 12,
             "CPUID vendor string must be 12 characters\n");

    _regClasses.emplace_back(NumIntRegs, debug::IntRegs);
    _regClasses.emplace_back(NumFloatRegs, debug::FloatRegs);
    _regClasses.emplace_back(1, debug::IntRegs); // Not applicable to X86
    _regClasses.emplace_back(2, debug::IntRegs); // Not applicable to X86
    _regClasses.emplace_back(1, debug::IntRegs); // Not applicable to X86
    _regClasses.emplace_back(NUM_CCREGS, debug::CCRegs);
    _regClasses.emplace_back(NUM_MISCREGS, debug::MiscRegs);

    clear();
}

static void
copyMiscRegs(ThreadContext *src, ThreadContext *dest)
{
    // This function assumes no side effects other than TLB invalidation
    // need to be considered while copying state. That will likely not be
    // true in the future.
    for (int i = 0; i < NUM_MISCREGS; ++i) {
        if (!isValidMiscReg(i))
             continue;

        dest->setMiscRegNoEffect(i, src->readMiscRegNoEffect(i));
    }

    // The TSC has to be updated with side-effects if the CPUs in a
    // CPU switch have different frequencies.
    dest->setMiscReg(MISCREG_TSC, src->readMiscReg(MISCREG_TSC));

    dest->getMMUPtr()->flushAll();
}

void
ISA::copyRegsFrom(ThreadContext *src)
{
    //copy int regs
    for (int i = 0; i < NumIntRegs; ++i)
         tc->setIntRegFlat(i, src->readIntRegFlat(i));
    //copy float regs
    for (int i = 0; i < NumFloatRegs; ++i)
         tc->setFloatRegFlat(i, src->readFloatRegFlat(i));
    //copy condition-code regs
    for (int i = 0; i < NUM_CCREGS; ++i)
         tc->setCCRegFlat(i, src->readCCRegFlat(i));
    copyMiscRegs(src, tc);
    tc->pcState(src->pcState());
}

RegVal
ISA::readMiscRegNoEffect(int miscReg) const
{
    // Make sure we're not dealing with an illegal control register.
    // Instructions should filter out these indexes, and nothing else should
    // attempt to read them directly.
    assert(isValidMiscReg(miscReg));

    return regVal[miscReg];
}

RegVal
ISA::readMiscReg(int miscReg)
{
    if (miscReg == MISCREG_TSC) {
        return regVal[MISCREG_TSC] + tc->getCpuPtr()->curCycle();
    }

    if (miscReg == MISCREG_FSW) {
        RegVal fsw = regVal[MISCREG_FSW];
        RegVal top = regVal[MISCREG_X87_TOP];
        return insertBits(fsw, 13, 11, top);
    }

    if (miscReg == MISCREG_APIC_BASE) {
        LocalApicBase base = regVal[MISCREG_APIC_BASE];
        base.bsp = (tc->contextId() == 0);
        return base;
    }

    return readMiscRegNoEffect(miscReg);
}

void
ISA::setMiscRegNoEffect(int miscReg, RegVal val)
{
    // Make sure we're not dealing with an illegal control register.
    // Instructions should filter out these indexes, and nothing else should
    // attempt to write to them directly.
    assert(isValidMiscReg(miscReg));

    HandyM5Reg m5Reg = regVal[MISCREG_M5_REG];
    int reg_width = 64;
    switch (miscReg) {
      case MISCREG_X87_TOP:
        reg_width = 3;
        break;
      case MISCREG_FTW:
        reg_width = 8;
        break;
      case MISCREG_FSW:
      case MISCREG_FCW:
      case MISCREG_FOP:
        reg_width = 16;
        break;
      case MISCREG_MXCSR:
        reg_width = 32;
        break;
      case MISCREG_FISEG:
      case MISCREG_FOSEG:
        if (m5Reg.submode != SixtyFourBitMode)
            reg_width = 16;
        break;
      case MISCREG_FIOFF:
      case MISCREG_FOOFF:
        if (m5Reg.submode != SixtyFourBitMode)
            reg_width = 32;
        break;
      default:
        break;
    }

    regVal[miscReg] = val & mask(reg_width);
}

void
ISA::setMiscReg(int miscReg, RegVal val)
{
    RegVal newVal = val;
    switch(miscReg)
    {
      case MISCREG_CR0:
        {
            CR0 toggled = regVal[miscReg] ^ val;
            CR0 newCR0 = val;
            Efer efer = regVal[MISCREG_EFER];
            if (toggled.pg && efer.lme) {
                if (newCR0.pg) {
                    //Turning on long mode
                    efer.lma = 1;
                    regVal[MISCREG_EFER] = efer;
                } else {
                    //Turning off long mode
                    efer.lma = 0;
                    regVal[MISCREG_EFER] = efer;
                }
            }
            if (toggled.pg) {
                tc->getMMUPtr()->flushAll();
            }
            //This must always be 1.
            newCR0.et = 1;
            newVal = newCR0;
            updateHandyM5Reg(regVal[MISCREG_EFER],
                             newCR0,
                             regVal[MISCREG_CS_ATTR],
                             regVal[MISCREG_SS_ATTR],
                             regVal[MISCREG_RFLAGS]);
        }
        break;
      case MISCREG_CR2:
        break;
      case MISCREG_CR3:
        static_cast<MMU *>(tc->getMMUPtr())->flushNonGlobal();
        break;
      case MISCREG_CR4:
        {
            CR4 toggled = regVal[miscReg] ^ val;
            if (toggled.pae || toggled.pse || toggled.pge) {
                tc->getMMUPtr()->flushAll();
            }
        }
        break;
      case MISCREG_CR8:
        break;
      case MISCREG_RFLAGS:
        {
            RFLAGS rflags = val;
            panic_if(rflags.vm, "Virtual 8086 mode is not supported.");
            break;
        }
      case MISCREG_CS_ATTR:
        {
            SegAttr toggled = regVal[miscReg] ^ val;
            SegAttr newCSAttr = val;
            if (toggled.longMode) {
                if (newCSAttr.longMode) {
                    regVal[MISCREG_ES_EFF_BASE] = 0;
                    regVal[MISCREG_CS_EFF_BASE] = 0;
                    regVal[MISCREG_SS_EFF_BASE] = 0;
                    regVal[MISCREG_DS_EFF_BASE] = 0;
                } else {
                    regVal[MISCREG_ES_EFF_BASE] = regVal[MISCREG_ES_BASE];
                    regVal[MISCREG_CS_EFF_BASE] = regVal[MISCREG_CS_BASE];
                    regVal[MISCREG_SS_EFF_BASE] = regVal[MISCREG_SS_BASE];
                    regVal[MISCREG_DS_EFF_BASE] = regVal[MISCREG_DS_BASE];
                }
            }
            updateHandyM5Reg(regVal[MISCREG_EFER],
                             regVal[MISCREG_CR0],
                             newCSAttr,
                             regVal[MISCREG_SS_ATTR],
                             regVal[MISCREG_RFLAGS]);
        }
        break;
      case MISCREG_SS_ATTR:
        updateHandyM5Reg(regVal[MISCREG_EFER],
                         regVal[MISCREG_CR0],
                         regVal[MISCREG_CS_ATTR],
                         val,
                         regVal[MISCREG_RFLAGS]);
        break;
      // These segments always actually use their bases, or in other words
      // their effective bases must stay equal to their actual bases.
      case MISCREG_FS_BASE:
      case MISCREG_GS_BASE:
      case MISCREG_HS_BASE:
      case MISCREG_TSL_BASE:
      case MISCREG_TSG_BASE:
      case MISCREG_TR_BASE:
      case MISCREG_IDTR_BASE:
        regVal[MISCREG_SEG_EFF_BASE(miscReg - MISCREG_SEG_BASE_BASE)] = val;
        break;
      // These segments ignore their bases in 64 bit mode.
      // their effective bases must stay equal to their actual bases.
      case MISCREG_ES_BASE:
      case MISCREG_CS_BASE:
      case MISCREG_SS_BASE:
      case MISCREG_DS_BASE:
        {
            Efer efer = regVal[MISCREG_EFER];
            SegAttr csAttr = regVal[MISCREG_CS_ATTR];
            if (!efer.lma || !csAttr.longMode) // Check for non 64 bit mode.
                regVal[MISCREG_SEG_EFF_BASE(miscReg -
                        MISCREG_SEG_BASE_BASE)] = val;
        }
        break;
      case MISCREG_TSC:
        regVal[MISCREG_TSC] = val - tc->getCpuPtr()->curCycle();
        return;
      case MISCREG_DR0:
      case MISCREG_DR1:
      case MISCREG_DR2:
      case MISCREG_DR3:
        /* These should eventually set up breakpoints. */
        break;
      case MISCREG_DR4:
        miscReg = MISCREG_DR6;
        [[fallthrough]];
      case MISCREG_DR6:
        {
            DR6 dr6 = regVal[MISCREG_DR6];
            DR6 newDR6 = val;
            dr6.b0 = newDR6.b0;
            dr6.b1 = newDR6.b1;
            dr6.b2 = newDR6.b2;
            dr6.b3 = newDR6.b3;
            dr6.bd = newDR6.bd;
            dr6.bs = newDR6.bs;
            dr6.bt = newDR6.bt;
            newVal = dr6;
        }
        break;
      case MISCREG_DR5:
        miscReg = MISCREG_DR7;
        [[fallthrough]];
      case MISCREG_DR7:
        {
            DR7 dr7 = regVal[MISCREG_DR7];
            DR7 newDR7 = val;
            dr7.l0 = newDR7.l0;
            dr7.g0 = newDR7.g0;
            if (dr7.l0 || dr7.g0) {
                panic("Debug register breakpoints not implemented.\n");
            } else {
                /* Disable breakpoint 0. */
            }
            dr7.l1 = newDR7.l1;
            dr7.g1 = newDR7.g1;
            if (dr7.l1 || dr7.g1) {
                panic("Debug register breakpoints not implemented.\n");
            } else {
                /* Disable breakpoint 1. */
            }
            dr7.l2 = newDR7.l2;
            dr7.g2 = newDR7.g2;
            if (dr7.l2 || dr7.g2) {
                panic("Debug register breakpoints not implemented.\n");
            } else {
                /* Disable breakpoint 2. */
            }
            dr7.l3 = newDR7.l3;
            dr7.g3 = newDR7.g3;
            if (dr7.l3 || dr7.g3) {
                panic("Debug register breakpoints not implemented.\n");
            } else {
                /* Disable breakpoint 3. */
            }
            dr7.gd = newDR7.gd;
            dr7.rw0 = newDR7.rw0;
            dr7.len0 = newDR7.len0;
            dr7.rw1 = newDR7.rw1;
            dr7.len1 = newDR7.len1;
            dr7.rw2 = newDR7.rw2;
            dr7.len2 = newDR7.len2;
            dr7.rw3 = newDR7.rw3;
            dr7.len3 = newDR7.len3;
        }
        break;
      case MISCREG_M5_REG:
        // Writing anything to the m5reg with side effects makes it update
        // based on the current values of the relevant registers. The actual
        // value written is discarded.
        updateHandyM5Reg(regVal[MISCREG_EFER],
                         regVal[MISCREG_CR0],
                         regVal[MISCREG_CS_ATTR],
                         regVal[MISCREG_SS_ATTR],
                         regVal[MISCREG_RFLAGS]);
        return;
      default:
        break;
    }
    setMiscRegNoEffect(miscReg, newVal);
}

void
ISA::serialize(CheckpointOut &cp) const
{
    SERIALIZE_ARRAY(regVal, NUM_MISCREGS);
}

void
ISA::unserialize(CheckpointIn &cp)
{
    UNSERIALIZE_ARRAY(regVal, NUM_MISCREGS);
    updateHandyM5Reg(regVal[MISCREG_EFER],
                     regVal[MISCREG_CR0],
                     regVal[MISCREG_CS_ATTR],
                     regVal[MISCREG_SS_ATTR],
                     regVal[MISCREG_RFLAGS]);
}

void
ISA::setThreadContext(ThreadContext *_tc)
{
    BaseISA::setThreadContext(_tc);
    tc->getDecoderPtr()->as<Decoder>().setM5Reg(regVal[MISCREG_M5_REG]);
}

std::string
ISA::getVendorString() const
{
    return vendorString;
}

} // namespace X86ISA
} // namespace gem5