xref: /gem5/util/statetrace/arch/amd64/tracechild.cc

/*
 * Copyright (c) 2007 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.
 *
 * Authors: Gabe Black
 */

#include <sys/ptrace.h>
#include <stdint.h>

#include <cerrno>
#include <cstring>
#include <iomanip>
#include <iostream>

#include "arch/amd64/tracechild.hh"

using namespace std;

bool
AMD64TraceChild::sendState(int socket)
{
    uint64_t regVal64 = 0;
    uint32_t regVal32 = 0;
    for (int x = 0; x <= R15; x++) {
        regVal64 = getRegVal(x);
        if (write(socket, &regVal64, sizeof(regVal64)) == -1) {
            cerr << "Write failed! " << strerror(errno) << endl;
            tracing = false;
            return false;
        }
    }
    regVal64 = getRegVal(RIP);
    if (write(socket, &regVal64, sizeof(regVal64)) == -1) {
        cerr << "Write failed! " << strerror(errno) << endl;
        tracing = false;
        return false;
    }
    for (int x = MMX0_0; x <= MMX7_1; x++) {
        regVal32 = getRegVal(x);
        if (write(socket, &regVal32, sizeof(regVal32)) == -1) {
            cerr << "Write failed! " << strerror(errno) << endl;
            tracing = false;
            return false;
        }
    }
    for (int x = XMM0_0; x <= XMM15_3; x++) {
        regVal32 = getRegVal(x);
        if (write(socket, &regVal32, sizeof(regVal32)) == -1) {
            cerr << "Write failed! " << strerror(errno) << endl;
            tracing = false;
            return false;
        }
    }
    return true;
}

int64_t
AMD64TraceChild::getRegs(user_regs_struct & myregs,
        user_fpregs_struct & myfpregs, int num)
{
    assert(num < numregs && num >= 0);
    switch (num) {
      //GPRs
      case RAX: return myregs.rax;
      case RBX: return myregs.rbx;
      case RCX: return myregs.rcx;
      case RDX: return myregs.rdx;
      //Index registers
      case RSI: return myregs.rsi;
      case RDI: return myregs.rdi;
      //Base pointer and stack pointer
      case RBP: return myregs.rbp;
      case RSP: return myregs.rsp;
      //New 64 bit mode registers
      case R8: return myregs.r8;
      case R9: return myregs.r9;
      case R10: return myregs.r10;
      case R11: return myregs.r11;
      case R12: return myregs.r12;
      case R13: return myregs.r13;
      case R14: return myregs.r14;
      case R15: return myregs.r15;
      //Segmentation registers
      case CS: return myregs.cs;
      case DS: return myregs.ds;
      case ES: return myregs.es;
      case FS: return myregs.fs;
      case GS: return myregs.gs;
      case SS: return myregs.ss;
      case FS_BASE: return myregs.fs_base;
      case GS_BASE: return myregs.gs_base;
      //PC
      case RIP: return myregs.rip;
      //Flags
      case EFLAGS: return myregs.eflags;
      //MMX
      case MMX0_0: return myfpregs.st_space[0];
      case MMX0_1: return myfpregs.st_space[1];
      case MMX1_0: return myfpregs.st_space[2];
      case MMX1_1: return myfpregs.st_space[3];
      case MMX2_0: return myfpregs.st_space[4];
      case MMX2_1: return myfpregs.st_space[5];
      case MMX3_0: return myfpregs.st_space[6];
      case MMX3_1: return myfpregs.st_space[7];
      case MMX4_0: return myfpregs.st_space[8];
      case MMX4_1: return myfpregs.st_space[9];
      case MMX5_0: return myfpregs.st_space[10];
      case MMX5_1: return myfpregs.st_space[11];
      case MMX6_0: return myfpregs.st_space[12];
      case MMX6_1: return myfpregs.st_space[13];
      case MMX7_0: return myfpregs.st_space[14];
      case MMX7_1: return myfpregs.st_space[15];
      //XMM
      case XMM0_0: return myfpregs.xmm_space[0];
      case XMM0_1: return myfpregs.xmm_space[1];
      case XMM0_2: return myfpregs.xmm_space[2];
      case XMM0_3: return myfpregs.xmm_space[3];
      case XMM1_0: return myfpregs.xmm_space[4];
      case XMM1_1: return myfpregs.xmm_space[5];
      case XMM1_2: return myfpregs.xmm_space[6];
      case XMM1_3: return myfpregs.xmm_space[7];
      case XMM2_0: return myfpregs.xmm_space[8];
      case XMM2_1: return myfpregs.xmm_space[9];
      case XMM2_2: return myfpregs.xmm_space[10];
      case XMM2_3: return myfpregs.xmm_space[11];
      case XMM3_0: return myfpregs.xmm_space[12];
      case XMM3_1: return myfpregs.xmm_space[13];
      case XMM3_2: return myfpregs.xmm_space[14];
      case XMM3_3: return myfpregs.xmm_space[15];
      case XMM4_0: return myfpregs.xmm_space[16];
      case XMM4_1: return myfpregs.xmm_space[17];
      case XMM4_2: return myfpregs.xmm_space[18];
      case XMM4_3: return myfpregs.xmm_space[19];
      case XMM5_0: return myfpregs.xmm_space[20];
      case XMM5_1: return myfpregs.xmm_space[21];
      case XMM5_2: return myfpregs.xmm_space[22];
      case XMM5_3: return myfpregs.xmm_space[23];
      case XMM6_0: return myfpregs.xmm_space[24];
      case XMM6_1: return myfpregs.xmm_space[25];
      case XMM6_2: return myfpregs.xmm_space[26];
      case XMM6_3: return myfpregs.xmm_space[27];
      case XMM7_0: return myfpregs.xmm_space[28];
      case XMM7_1: return myfpregs.xmm_space[29];
      case XMM7_2: return myfpregs.xmm_space[30];
      case XMM7_3: return myfpregs.xmm_space[31];
      case XMM8_0: return myfpregs.xmm_space[32];
      case XMM8_1: return myfpregs.xmm_space[33];
      case XMM8_2: return myfpregs.xmm_space[34];
      case XMM8_3: return myfpregs.xmm_space[35];
      case XMM9_0: return myfpregs.xmm_space[36];
      case XMM9_1: return myfpregs.xmm_space[37];
      case XMM9_2: return myfpregs.xmm_space[38];
      case XMM9_3: return myfpregs.xmm_space[39];
      case XMM10_0: return myfpregs.xmm_space[40];
      case XMM10_1: return myfpregs.xmm_space[41];
      case XMM10_2: return myfpregs.xmm_space[42];
      case XMM10_3: return myfpregs.xmm_space[43];
      case XMM11_0: return myfpregs.xmm_space[44];
      case XMM11_1: return myfpregs.xmm_space[45];
      case XMM11_2: return myfpregs.xmm_space[46];
      case XMM11_3: return myfpregs.xmm_space[47];
      case XMM12_0: return myfpregs.xmm_space[48];
      case XMM12_1: return myfpregs.xmm_space[49];
      case XMM12_2: return myfpregs.xmm_space[50];
      case XMM12_3: return myfpregs.xmm_space[51];
      case XMM13_0: return myfpregs.xmm_space[52];
      case XMM13_1: return myfpregs.xmm_space[53];
      case XMM13_2: return myfpregs.xmm_space[54];
      case XMM13_3: return myfpregs.xmm_space[55];
      case XMM14_0: return myfpregs.xmm_space[56];
      case XMM14_1: return myfpregs.xmm_space[57];
      case XMM14_2: return myfpregs.xmm_space[58];
      case XMM14_3: return myfpregs.xmm_space[59];
      case XMM15_0: return myfpregs.xmm_space[60];
      case XMM15_1: return myfpregs.xmm_space[61];
      case XMM15_2: return myfpregs.xmm_space[62];
      case XMM15_3: return myfpregs.xmm_space[63];
      default:
        assert(0);
        return 0;
    }
}

bool
AMD64TraceChild::update(int pid)
{
    oldregs = regs;
    oldfpregs = fpregs;
    if (ptrace(PTRACE_GETREGS, pid, 0, &regs) != 0) {
        cerr << "update: " << strerror(errno) << endl;
        return false;
    }
    if (ptrace(PTRACE_GETFPREGS, pid, 0, &fpregs) != 0) {
        cerr << "update: " << strerror(errno) << endl;
        return false;
    }
    for (unsigned int x = 0; x < numregs; x++)
        regDiffSinceUpdate[x] = (getRegVal(x) != getOldRegVal(x));
    return true;
}

AMD64TraceChild::AMD64TraceChild()
{
    for (unsigned int x = 0; x < numregs; x++)
        regDiffSinceUpdate[x] = false;
}

int64_t
AMD64TraceChild::getRegVal(int num)
{
    return getRegs(regs, fpregs, num);
}

int64_t
AMD64TraceChild::getOldRegVal(int num)
{
    return getRegs(oldregs, oldfpregs, num);
}

ostream &
AMD64TraceChild::outputStartState(ostream & os)
{
    uint64_t sp = getSP();
    uint64_t pc = getPC();
    uint64_t highestInfo = 0;
    char obuf[1024];
    sprintf(obuf, "Initial stack pointer = 0x%016lx\n", sp);
    os << obuf;
    sprintf(obuf, "Initial program counter = 0x%016lx\n", pc);
    os << obuf;

    //Output the argument count
    uint64_t cargc = ptrace(PTRACE_PEEKDATA, pid, sp, 0);
    sprintf(obuf, "0x%016lx: Argc = 0x%016lx\n", sp, cargc);
    os << obuf;
    sp += 8;

    //Output argv pointers
    int argCount = 0;
    uint64_t cargv;
    do {
        cargv = ptrace(PTRACE_PEEKDATA, pid, sp, 0);
        sprintf(obuf, "0x%016lx: argv[%d] = 0x%016lx\n",
                sp, argCount++, cargv);
        if (cargv)
            if (highestInfo < cargv)
                highestInfo = cargv;
        os << obuf;
        sp += 8;
    } while (cargv);

    //Output the envp pointers
    int envCount = 0;
    uint64_t cenvp;
    do {
        cenvp = ptrace(PTRACE_PEEKDATA, pid, sp, 0);
        sprintf(obuf, "0x%016lx: envp[%d] = 0x%016lx\n",
                sp, envCount++, cenvp);
        os << obuf;
        sp += 8;
    } while (cenvp);
    uint64_t auxType, auxVal;
    do {
        auxType = ptrace(PTRACE_PEEKDATA, pid, sp, 0);
        sp += 8;
        auxVal = ptrace(PTRACE_PEEKDATA, pid, sp, 0);
        sp += 8;
        sprintf(obuf, "0x%016lx: Auxiliary vector = {0x%016lx, 0x%016lx}\n",
                sp - 16, auxType, auxVal);
        os << obuf;
    } while (auxType != 0 || auxVal != 0);
    //Print out the argument strings, environment strings, and file name.
    string current;
    uint64_t buf;
    uint64_t currentStart = sp;
    bool clearedInitialPadding = false;
    do {
        buf = ptrace(PTRACE_PEEKDATA, pid, sp, 0);
        char * cbuf = (char *)&buf;
        for (int x = 0; x < sizeof(uint64_t); x++) {
            if (cbuf[x])
                current += cbuf[x];
            else {
                sprintf(obuf, "0x%016lx: \"%s\"\n",
                        currentStart, current.c_str());
                os << obuf;
                current = "";
                currentStart = sp + x + 1;
            }
        }
        sp += 8;
        clearedInitialPadding = clearedInitialPadding || buf != 0;
    } while (!clearedInitialPadding || buf != 0 || sp <= highestInfo);
    return os;
}

uint64_t
AMD64TraceChild::findSyscall()
{
    uint64_t rip = getPC();
    bool foundOpcode = false;
    bool twoByteOpcode = false;
    for (;;) {
        uint64_t buf = ptrace(PTRACE_PEEKDATA, pid, rip, 0);
        for (int i = 0; i < sizeof(uint64_t); i++) {
            unsigned char byte = buf & 0xFF;
            if (!foundOpcode) {
                if (!(byte == 0x66 || //operand override
                     byte == 0x67 || //address override
                     byte == 0x2E || //cs
                     byte == 0x3E || //ds
                     byte == 0x26 || //es
                     byte == 0x64 || //fs
                     byte == 0x65 || //gs
                     byte == 0x36 || //ss
                     byte == 0xF0 || //lock
                     byte == 0xF2 || //repe
                     byte == 0xF3 || //repne
                     (byte >= 0x40 && byte <= 0x4F) // REX
                    )) {
                    foundOpcode = true;
                }
            }
            if (foundOpcode) {
                if (twoByteOpcode) {
                    //SYSCALL or SYSENTER
                    if (byte == 0x05 || byte == 0x34)
                        return rip + 1;
                    else
                        return 0;
                }
                if (!twoByteOpcode) {
                    if (byte == 0xCC) // INT3
                        return rip + 1;
                    else if (byte == 0xCD) // INT with byte immediate
                        return rip + 2;
                    else if (byte == 0x0F) // two byte opcode prefix
                        twoByteOpcode = true;
                    else
                        return 0;
                }
            }
            buf >>= 8;
            rip++;
        }
    }
}

bool
AMD64TraceChild::step()
{
    uint64_t ripAfterSyscall = findSyscall();
    if (ripAfterSyscall) {
        //Get the original contents of memory
        uint64_t buf = ptrace(PTRACE_PEEKDATA, pid, ripAfterSyscall, 0);
        //Patch the first two bytes of the memory immediately after this with
        //jmp -2. Either single stepping will take over before this
        //instruction, leaving the rip where it should be, or it will take
        //over after this instruction, -still- leaving the rip where it should
        //be.
        uint64_t newBuf = (buf & ~0xFFFF) | 0xFEEB;
        //Write the patched memory to the processes address space
        ptrace(PTRACE_POKEDATA, pid, ripAfterSyscall, newBuf);
        //Step and hit it
        ptraceSingleStep();
        //Put things back to the way they started
        ptrace(PTRACE_POKEDATA, pid, ripAfterSyscall, buf);
    } else {
        //Get all the way past repe and repne string instructions in one shot.
        uint64_t newPC, origPC = getPC();
        do {
            ptraceSingleStep();
            newPC = getPC();
        } while (newPC == origPC);
    }
}

TraceChild * genTraceChild()
{
    return new AMD64TraceChild;
}