debuggerd/mips/machine.cpp

/*
 * Copyright 2012, The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/ptrace.h>

#include <corkscrew/ptrace.h>

#include <sys/user.h>

#include "../utility.h"
#include "../machine.h"

// enable to dump memory pointed to by every register
#define DUMP_MEMORY_FOR_ALL_REGISTERS 1

#define R(x) (static_cast<unsigned int>(x))

static void dump_memory(log_t* log, pid_t tid, uintptr_t addr, int scope_flags) {
  char code_buffer[64];       // actual 8+1+((8+1)*4) + 1 == 45
  char ascii_buffer[32];      // actual 16 + 1 == 17
  uintptr_t p, end;

  p = addr & ~3;
  p -= 32;
  if (p > addr) {
    // catch underflow
    p = 0;
  }
  end = p + 80;
  // catch overflow; 'end - p' has to be multiples of 16
  while (end < p)
    end -= 16;

  // Dump the code around PC as:
  //  addr     contents                             ascii
  //  00008d34 ef000000 e8bd0090 e1b00000 512fff1e  ............../Q
  //  00008d44 ea00b1f9 e92d0090 e3a070fc ef000000  ......-..p......
  while (p < end) {
    char* asc_out = ascii_buffer;

    sprintf(code_buffer, "%08x ", p);

    int i;
    for (i = 0; i < 4; i++) {
      // If we see (data == -1 && errno != 0), we know that the ptrace
      // call failed, probably because we're dumping memory in an
      // unmapped or inaccessible page.  I don't know if there's
      // value in making that explicit in the output -- it likely
      // just complicates parsing and clarifies nothing for the
      // enlightened reader.
      long data = ptrace(PTRACE_PEEKTEXT, tid, (void*)p, NULL);
      sprintf(code_buffer + strlen(code_buffer), "%08lx ", data);

      int j;
      for (j = 0; j < 4; j++) {
        // Our isprint() allows high-ASCII characters that display
        // differently (often badly) in different viewers, so we
        // just use a simpler test.
        char val = (data >> (j*8)) & 0xff;
        if (val >= 0x20 && val < 0x7f) {
          *asc_out++ = val;
        } else {
          *asc_out++ = '.';
        }
      }
      p += 4;
    }
    *asc_out = '\0';
    _LOG(log, scope_flags, "    %s %s\n", code_buffer, ascii_buffer);
  }
}

// If configured to do so, dump memory around *all* registers
// for the crashing thread.
void dump_memory_and_code(log_t* log, pid_t tid, int scope_flags) {
  pt_regs_mips_t r;
  if (ptrace(PTRACE_GETREGS, tid, 0, &r)) {
    return;
  }

  if (IS_AT_FAULT(scope_flags) && DUMP_MEMORY_FOR_ALL_REGISTERS) {
    static const char REG_NAMES[] = "$0atv0v1a0a1a2a3t0t1t2t3t4t5t6t7s0s1s2s3s4s5s6s7t8t9k0k1gpsps8ra";

    for (int reg = 0; reg < 32; reg++) {
      // skip uninteresting registers
      if (reg == 0 // $0
          || reg == 26 // $k0
          || reg == 27 // $k1
          || reg == 31 // $ra (done below)
         )
        continue;

      uintptr_t addr = R(r.regs[reg]);

      // Don't bother if it looks like a small int or ~= null, or if
      // it's in the kernel area.
      if (addr < 4096 || addr >= 0x80000000) {
        continue;
      }

      _LOG(log, scope_flags | SCOPE_SENSITIVE, "\nmemory near %.2s:\n", &REG_NAMES[reg * 2]);
      dump_memory(log, tid, addr, scope_flags | SCOPE_SENSITIVE);
    }
  }

  unsigned int pc = R(r.cp0_epc);
  unsigned int ra = R(r.regs[31]);

  _LOG(log, scope_flags, "\ncode around pc:\n");
  dump_memory(log, tid, (uintptr_t)pc, scope_flags);

  if (pc != ra) {
    _LOG(log, scope_flags, "\ncode around ra:\n");
    dump_memory(log, tid, (uintptr_t)ra, scope_flags);
  }
}

void dump_registers(log_t* log, pid_t tid, int scope_flags) {
  pt_regs_mips_t r;
  if(ptrace(PTRACE_GETREGS, tid, 0, &r)) {
    _LOG(log, scope_flags, "cannot get registers: %s\n", strerror(errno));
    return;
  }

  _LOG(log, scope_flags, " zr %08x  at %08x  v0 %08x  v1 %08x\n",
       R(r.regs[0]), R(r.regs[1]), R(r.regs[2]), R(r.regs[3]));
  _LOG(log, scope_flags, " a0 %08x  a1 %08x  a2 %08x  a3 %08x\n",
       R(r.regs[4]), R(r.regs[5]), R(r.regs[6]), R(r.regs[7]));
  _LOG(log, scope_flags, " t0 %08x  t1 %08x  t2 %08x  t3 %08x\n",
       R(r.regs[8]), R(r.regs[9]), R(r.regs[10]), R(r.regs[11]));
  _LOG(log, scope_flags, " t4 %08x  t5 %08x  t6 %08x  t7 %08x\n",
       R(r.regs[12]), R(r.regs[13]), R(r.regs[14]), R(r.regs[15]));
  _LOG(log, scope_flags, " s0 %08x  s1 %08x  s2 %08x  s3 %08x\n",
       R(r.regs[16]), R(r.regs[17]), R(r.regs[18]), R(r.regs[19]));
  _LOG(log, scope_flags, " s4 %08x  s5 %08x  s6 %08x  s7 %08x\n",
       R(r.regs[20]), R(r.regs[21]), R(r.regs[22]), R(r.regs[23]));
  _LOG(log, scope_flags, " t8 %08x  t9 %08x  k0 %08x  k1 %08x\n",
       R(r.regs[24]), R(r.regs[25]), R(r.regs[26]), R(r.regs[27]));
  _LOG(log, scope_flags, " gp %08x  sp %08x  s8 %08x  ra %08x\n",
       R(r.regs[28]), R(r.regs[29]), R(r.regs[30]), R(r.regs[31]));
  _LOG(log, scope_flags, " hi %08x  lo %08x bva %08x epc %08x\n",
       R(r.hi), R(r.lo), R(r.cp0_badvaddr), R(r.cp0_epc));
}