Linux中访问另一个进程虚拟内存（调试）

Linux上gdb如何访问另一个进程的虚拟内存？都是通过/proc完成的吗？

Linux上gdb如何访问另一个进程的虚拟内存？都是通过/proc完成的吗？

在Linux上读取内存:

1) 如果要读取的字节数小于3 * sizeof (long)或文件系统/proc不可用或正在读取/proc/PID/mem那么不成功ptrace与使用PTRACE_PEEKTEXT读取数据。

这些是函数中的条件linux_proc_xfer_partial():

  /* Don't bother for one word.  */
  if (len < 3 * sizeof (long))
    return 0;

  /* We could keep this file open and cache it - possibly one per
     thread.  That requires some juggling, but is even faster.  */
  xsnprintf (filename, sizeof filename, "/proc/%d/mem",
         ptid_get_pid (inferior_ptid));
  fd = gdb_open_cloexec (filename, O_RDONLY | O_LARGEFILE, 0);
  if (fd == -1)
    return 0;

2) 如果要读取的字节数大于或等于 3 * sizeof (long) 且/proc那么可用pread64 or (lseek() and read()使用：

static LONGEST
linux_proc_xfer_partial (struct target_ops *ops, enum target_object object,
             const char *annex, gdb_byte *readbuf,
             const gdb_byte *writebuf,
             ULONGEST offset, LONGEST len)
{
  .....

  /* If pread64 is available, use it.  It's faster if the kernel
     supports it (only one syscall), and it's 64-bit safe even on
     32-bit platforms (for instance, SPARC debugging a SPARC64
     application).  */
#ifdef HAVE_PREAD64
  if (pread64 (fd, readbuf, len, offset) != len)
#else
  if (lseek (fd, offset, SEEK_SET) == -1 || read (fd, readbuf, len) != len)
#endif
    ret = 0;
  else
    ret = len;

  close (fd);
  return ret;
}

在Linux上写入内存:

1) ptrace with PTRACE_POKETEXT or PTRACE_POKEDATA用来。

我在哪里可以找到有关...设置硬件观察点的信息

gdb，内部观察点：shttp://sourceware.org/gdb/wiki/Internals%20Watchpoints http://sourceware.org/gdb/wiki/Internals%20Watchpoints

参考：

• http://linux.die.net/man/2/ptrace http://linux.die.net/man/2/ptrace
• http://www.alexonlinux.com/how-debugger-works http://www.alexonlinux.com/how-debugger-works