tracechild.cc revision 8108 
1/*
2 * Copyright (c) 2010 ARM Limited
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 * Copyright (c) 2006-2009 The Regents of The University of Michigan
15 * All rights reserved.
16 *
17 * Redistribution and use in source and binary forms, with or without
18 * modification, are permitted provided that the following conditions are
19 * met: redistributions of source code must retain the above copyright
20 * notice, this list of conditions and the following disclaimer;
21 * redistributions in binary form must reproduce the above copyright
22 * notice, this list of conditions and the following disclaimer in the
23 * documentation and/or other materials provided with the distribution;
24 * neither the name of the copyright holders nor the names of its
25 * contributors may be used to endorse or promote products derived from
26 * this software without specific prior written permission.
27 *
28 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
29 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
30 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
31 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
32 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
33 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
34 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
35 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
36 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
37 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
38 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
39 *
40 * Authors: Ali Saidi
41 *          Gabe Black
42 */
43
44#include <iostream>
45#include <errno.h>
46#include <stdint.h>
47#include <cstring>
48#include <cstdio>
49
50#include "tracechild_arm.hh"
51
52using namespace std;
53
54const char* ARMTraceChild::regNames[numregs] = {
55    "r0", "r1", "r2", "r3", "r4", "r5", "r6", "r7",
56    "r8", "r9", "r10", "fp", "r12", "sp", "lr", "pc",
57    "cpsr" };
58
59
60ARMTraceChild::ARMTraceChild()
61{
62    foundMvn = false;
63
64    for (int x = 0; x < numregs; x++) {
65        memset(&regs, 0, sizeof(regs));
66        memset(&oldregs, 0, sizeof(regs));
67        regDiffSinceUpdate[x] = false;
68    }
69}
70
71bool
72ARMTraceChild::sendState(int socket)
73{
74    uint32_t regVal = 0;
75    uint32_t message[numregs + 1];
76    int pos = 1;
77    message[0] = 0;
78    for (int x = 0; x < numregs; x++) {
79        if (regDiffSinceUpdate[x]) {
80            message[0] = message[0] | (1 << x);
81            message[pos++] = getRegVal(x);
82        }
83    }
84
85    size_t sent = 0;
86    size_t toSend = pos * sizeof(message[0]);
87    uint8_t *messagePtr = (uint8_t *)message;
88    while (toSend != 0) {
89        sent = write(socket, messagePtr, toSend);
90        if (sent == -1) {
91            cerr << "Write failed! " << strerror(errno) << endl;
92            tracing = false;
93            return false;
94        }
95        toSend -= sent;
96        messagePtr += sent;
97    }
98
99    return true;
100}
101
102uint32_t
103ARMTraceChild::getRegs(user_regs &myregs, int num)
104{
105    assert(num < numregs && num >= 0);
106    return myregs.uregs[num];
107}
108
109bool
110ARMTraceChild::update(int pid)
111{
112    oldregs = regs;
113    if (ptrace(PTRACE_GETREGS, pid, 0, &regs) != 0) {
114        cerr << "update: " << strerror(errno) << endl;
115        return false;
116    }
117
118    for (unsigned int x = 0; x < numregs; x++)
119        regDiffSinceUpdate[x] = (getRegVal(x) != getOldRegVal(x));
120    return true;
121}
122
123int64_t
124ARMTraceChild::getRegVal(int num)
125{
126    return getRegs(regs, num);
127}
128
129int64_t
130ARMTraceChild::getOldRegVal(int num)
131{
132    return getRegs(oldregs,  num);
133}
134
135char *
136ARMTraceChild::printReg(int num)
137{
138    sprintf(printBuffer, "0x%08X", (uint32_t)getRegVal(num));
139    return printBuffer;
140}
141
142ostream &
143ARMTraceChild::outputStartState(ostream & os)
144{
145    uint32_t sp = getSP();
146    uint32_t pc = getPC();
147    uint32_t highestInfo = 0;
148    char obuf[1024];
149    sprintf(obuf, "Initial stack pointer = 0x%08x\n", sp);
150    os << obuf;
151    sprintf(obuf, "Initial program counter = 0x%08x\n", pc);
152    os << obuf;
153
154    //Output the argument count
155    int32_t cargc = ptrace(PTRACE_PEEKDATA, pid, sp, 0);
156    sprintf(obuf, "0x%08x: Argc = 0x%08x\n", sp, cargc);
157    os << obuf;
158    sp += 4;
159
160    //Output argv pointers
161    int argCount = 0;
162    int32_t cargv;
163    do {
164        cargv = ptrace(PTRACE_PEEKDATA, pid, sp, 0);
165        sprintf(obuf, "0x%08x: argv[%d] = 0x%08x\n",
166                sp, argCount++, cargv);
167        if(cargv)
168            if(highestInfo < cargv)
169                highestInfo = cargv;
170        os << obuf;
171        sp += 4;
172    } while(cargv);
173
174    //Output the envp pointers
175    int envCount = 0;
176    uint32_t cenvp;
177    do {
178        cenvp = ptrace(PTRACE_PEEKDATA, pid, sp, 0);
179        sprintf(obuf, "0x%08x: envp[%d] = 0x%08x\n",
180                sp, envCount++, cenvp);
181        os << obuf;
182        sp += 4;
183    } while(cenvp);
184    uint32_t auxType, auxVal;
185    do {
186        auxType = ptrace(PTRACE_PEEKDATA, pid, sp, 0);
187        sp += 4;
188        auxVal = ptrace(PTRACE_PEEKDATA, pid, sp, 0);
189        sp += 4;
190        sprintf(obuf, "0x%08x: Auxiliary vector = {0x%08x, 0x%08x}\n",
191                sp - 8, auxType, auxVal);
192        os << obuf;
193    } while(auxType != 0 || auxVal != 0);
194    //Print out the argument strings, environment strings, and file name.
195    string current;
196    uint32_t buf;
197    uint32_t currentStart = sp;
198    bool clearedInitialPadding = false;
199    do {
200        buf = ptrace(PTRACE_PEEKDATA, pid, sp, 0);
201        char * cbuf = (char *)&buf;
202        for (int x = 0; x < sizeof(uint32_t); x++) {
203            if (cbuf[x])
204                current += cbuf[x];
205            else {
206                sprintf(obuf, "0x%08x: \"%s\"\n",
207                        currentStart, current.c_str());
208                os << obuf;
209                current = "";
210                currentStart = sp + x + 1;
211            }
212        }
213        sp += 4;
214        clearedInitialPadding = clearedInitialPadding || buf != 0;
215    } while(!clearedInitialPadding || buf != 0 || sp <= highestInfo);
216    return os;
217}
218
219bool
220ARMTraceChild::step()
221{
222    const uint32_t bkpt_inst = 0xe7f001f0;
223
224    uint32_t lr = getRegVal(14);
225    uint32_t pc = getPC();
226    uint32_t lrOp, subsOp;
227    char obuf[128];
228    bool patch = false;
229
230    // Since ARM uses software breakpoints behind the scenes, they don't work
231    // in read only areas like the page of routines provided by the kernel. The
232    // link register generally holds the address the process wants to the
233    // kernel to return to after it's done, so we'll install a software
234    // breakpoint there.
235    //
236    // Calls into the kernel user page always follow the form:
237    //  MVN ...
238    //  <possible MOV lr,...>
239    //  SUB PC, ...
240    //
241    //  So we look for this pattern and set a breakpoint on the LR at the SUB
242    //  instruction.
243
244
245    subsOp = ptrace(PTRACE_PEEKDATA, pid, pc, 0);
246    if ((subsOp & 0xFFFF0FFF) == 0xe3e00a0f)
247        foundMvn = true;
248
249    if (foundMvn && ((subsOp & 0xFFF0F000) == 0xe240f000)) {
250        foundMvn = false;
251        lrOp = ptrace(PTRACE_PEEKDATA, pid, lr, 0);
252        ptrace(PTRACE_POKEDATA, pid, lr, bkpt_inst);
253        patch = true;
254    }
255    ptraceSingleStep();
256
257    if (patch)
258        ptrace(PTRACE_POKEDATA, pid, lr, lrOp);
259}
260
261
262TraceChild *
263genTraceChild()
264{
265    return new ARMTraceChild;
266}
267
268