android_system_core/debuggerd/arm/machine.cpp

/*
 *
 * Copyright 2006, 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 <errno.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ptrace.h>
#include <sys/types.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

#ifdef WITH_VFP
#ifdef WITH_VFP_D32
#define NUM_VFP_REGS 32
#else
#define NUM_VFP_REGS 16
#endif
#endif

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;
  }
  // Dump more memory content for the crashing thread.
  end = p + 256;
  // 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, reinterpret_cast<void*>(p), NULL);
      sprintf(code_buffer + strlen(code_buffer), "%08lx ", data);

      // Enable the following code blob to dump ASCII values
#if 0
      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++ = '.';
        }
      }
#endif
      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) {
  struct pt_regs regs;
  if (ptrace(PTRACE_GETREGS, tid, 0, &regs)) {
    return;
  }

  if (IS_AT_FAULT(scope_flags) && DUMP_MEMORY_FOR_ALL_REGISTERS) {
    static const char REG_NAMES[] = "r0r1r2r3r4r5r6r7r8r9slfpipsp";

    for (int reg = 0; reg < 14; reg++) {
      // this may not be a valid way to access, but it'll do for now
      uintptr_t addr = regs.uregs[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 >= 0xc0000000) {
        continue;
      }

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

  // explicitly allow upload of code dump logging
  _LOG(log, scope_flags, "\ncode around pc:\n");
  dump_memory(log, tid, static_cast<uintptr_t>(regs.ARM_pc), scope_flags);

  if (regs.ARM_pc != regs.ARM_lr) {
    _LOG(log, scope_flags, "\ncode around lr:\n");
    dump_memory(log, tid, static_cast<uintptr_t>(regs.ARM_lr), scope_flags);
  }
}

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

  _LOG(log, scope_flags, "    r0 %08x  r1 %08x  r2 %08x  r3 %08x\n",
       static_cast<uint32_t>(r.ARM_r0), static_cast<uint32_t>(r.ARM_r1),
       static_cast<uint32_t>(r.ARM_r2), static_cast<uint32_t>(r.ARM_r3));
  _LOG(log, scope_flags, "    r4 %08x  r5 %08x  r6 %08x  r7 %08x\n",
       static_cast<uint32_t>(r.ARM_r4), static_cast<uint32_t>(r.ARM_r5),
       static_cast<uint32_t>(r.ARM_r6), static_cast<uint32_t>(r.ARM_r7));
  _LOG(log, scope_flags, "    r8 %08x  r9 %08x  sl %08x  fp %08x\n",
       static_cast<uint32_t>(r.ARM_r8), static_cast<uint32_t>(r.ARM_r9),
       static_cast<uint32_t>(r.ARM_r10), static_cast<uint32_t>(r.ARM_fp));
  _LOG(log, scope_flags, "    ip %08x  sp %08x  lr %08x  pc %08x  cpsr %08x\n",
       static_cast<uint32_t>(r.ARM_ip), static_cast<uint32_t>(r.ARM_sp),
       static_cast<uint32_t>(r.ARM_lr), static_cast<uint32_t>(r.ARM_pc),
       static_cast<uint32_t>(r.ARM_cpsr));

#ifdef WITH_VFP
  struct user_vfp vfp_regs;
  int i;

  if (ptrace(PTRACE_GETVFPREGS, tid, 0, &vfp_regs)) {
    _LOG(log, scope_flags, "cannot get registers: %s\n", strerror(errno));
    return;
  }

  for (i = 0; i < NUM_VFP_REGS; i += 2) {
    _LOG(log, scope_flags, "    d%-2d %016llx  d%-2d %016llx\n",
         i, vfp_regs.fpregs[i], i+1, vfp_regs.fpregs[i+1]);
  }
  _LOG(log, scope_flags, "    scr %08lx\n", vfp_regs.fpscr);
#endif
}