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/* BSD Kernel Data Access Library (libkvm) interface.

   Copyright (C) 2004, 2005, 2007, 2008, 2009, 2010

   Free Software Foundation, Inc.

   This file is part of GDB.

   This program is free software; you can redistribute it and/or modify

   it under the terms of the GNU General Public License as published by

   the Free Software Foundation; either version 3 of the License, or

   (at your option) any later version.

   This program is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License

   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

#include "defs.h"

#include "cli/cli-cmds.h"

#include "command.h"

#include "frame.h"

#include "regcache.h"

#include "target.h"

#include "value.h"

#include "gdbcore.h"            /* for get_exec_file */

#include "gdbthread.h"

#include "gdb_assert.h"

#include <fcntl.h>

#include <kvm.h>

#ifdef HAVE_NLIST_H

#include <nlist.h>

#endif

#include <paths.h>

#include "readline/readline.h"

#include <sys/param.h>

#include <sys/proc.h>

#include <sys/user.h>

#include "bsd-kvm.h"

/* Kernel memory device file.  */

static const char *bsd_kvm_corefile;

/* Kernel memory interface descriptor.  */

static kvm_t *core_kd;

/* Address of process control block.  */

static struct pcb *bsd_kvm_paddr;

/* Pointer to architecture-specific function that reconstructs the

   register state from PCB and supplies it to REGCACHE.  */

static int (*bsd_kvm_supply_pcb)(struct regcache *regcache, struct pcb *pcb);

/* Target ops for libkvm interface.  */

static struct target_ops bsd_kvm_ops;

/* This is the ptid we use while we're connected to kvm.  The kvm

   target currently doesn't export any view of the running processes,

   so this represents the kernel task.  */

static ptid_t bsd_kvm_ptid;

static void

bsd_kvm_open (char *filename, int from_tty)

{

  char errbuf[_POSIX2_LINE_MAX];

  char *execfile = NULL;

  kvm_t *temp_kd;

  target_preopen (from_tty);

  if (filename)

    {

      char *temp;

      filename = tilde_expand (filename);

      if (filename[0] != '/')

        {

          temp = concat (current_directory, "/", filename, (char *)NULL);

          xfree (filename);

          filename = temp;

        }

    }

  execfile = get_exec_file (0);

  temp_kd = kvm_openfiles (execfile, filename, NULL,

                           write_files ? O_RDWR : O_RDONLY, errbuf);

  if (temp_kd == NULL)

    error (("%s"), errbuf);

  bsd_kvm_corefile = filename;

  unpush_target (&bsd_kvm_ops);

  core_kd = temp_kd;

  push_target (&bsd_kvm_ops);

  add_thread_silent (bsd_kvm_ptid);

  inferior_ptid = bsd_kvm_ptid;

  target_fetch_registers (get_current_regcache (), -1);

  reinit_frame_cache ();

  print_stack_frame (get_selected_frame (NULL), -1, 1);

}

static void

bsd_kvm_close (int quitting)

{

  if (core_kd)

    {

      if (kvm_close (core_kd) == -1)

        warning (("%s"), kvm_geterr(core_kd));

      core_kd = NULL;

    }

  inferior_ptid = null_ptid;

  delete_thread_silent (bsd_kvm_ptid);

}

static LONGEST

bsd_kvm_xfer_memory (CORE_ADDR addr, ULONGEST len,

                     gdb_byte *readbuf, const gdb_byte *writebuf)

{

  ssize_t nbytes = len;

  if (readbuf)

    nbytes = kvm_read (core_kd, addr, readbuf, nbytes);

  if (writebuf && nbytes > 0)

    nbytes = kvm_write (core_kd, addr, writebuf, nbytes);

  return nbytes;

}

static LONGEST

bsd_kvm_xfer_partial (struct target_ops *ops, enum target_object object,

                      const char *annex, gdb_byte *readbuf,

                      const gdb_byte *writebuf,

                      ULONGEST offset, LONGEST len)

{

  switch (object)

    {

    case TARGET_OBJECT_MEMORY:

      return bsd_kvm_xfer_memory (offset, len, readbuf, writebuf);

    default:

      return -1;

    }

}

static void

bsd_kvm_files_info (struct target_ops *ops)

{

  if (bsd_kvm_corefile && strcmp (bsd_kvm_corefile, _PATH_MEM) != 0)

    printf_filtered (_("\tUsing the kernel crash dump %s.\n"),

                     bsd_kvm_corefile);

  else

    printf_filtered (_("\tUsing the currently running kernel.\n"));

}

/* Fetch process control block at address PADDR.  */

static int

bsd_kvm_fetch_pcb (struct regcache *regcache, struct pcb *paddr)

{

  struct pcb pcb;

  if (kvm_read (core_kd, (unsigned long) paddr, &pcb, sizeof pcb) == -1)

    error (("%s"), kvm_geterr (core_kd));

  gdb_assert (bsd_kvm_supply_pcb);

  return bsd_kvm_supply_pcb (regcache, &pcb);

}

static void

bsd_kvm_fetch_registers (struct target_ops *ops,

                         struct regcache *regcache, int regnum)

{

  struct nlist nl[2];

  if (bsd_kvm_paddr)

    {

      bsd_kvm_fetch_pcb (regcache, bsd_kvm_paddr);

      return;

    }

  /* On dumping core, BSD kernels store the faulting context (PCB)

     in the variable "dumppcb".  */

  memset (nl, 0, sizeof nl);

  nl[0].n_name = "_dumppcb";

  if (kvm_nlist (core_kd, nl) == -1)

    error (("%s"), kvm_geterr (core_kd));

  if (nl[0].n_value != 0)

    {

      /* Found dumppcb. If it contains a valid context, return

         immediately.  */

      if (bsd_kvm_fetch_pcb (regcache, (struct pcb *) nl[0].n_value))

        return;

    }

  /* Traditional BSD kernels have a process proc0 that should always

     be present.  The address of proc0's PCB is stored in the variable

     "proc0paddr".  */

  memset (nl, 0, sizeof nl);

  nl[0].n_name = "_proc0paddr";

  if (kvm_nlist (core_kd, nl) == -1)

    error (("%s"), kvm_geterr (core_kd));

  if (nl[0].n_value != 0)

    {

      struct pcb *paddr;

      /* Found proc0paddr.  */

      if (kvm_read (core_kd, nl[0].n_value, &paddr, sizeof paddr) == -1)

        error (("%s"), kvm_geterr (core_kd));

      bsd_kvm_fetch_pcb (regcache, paddr);

      return;

    }

#ifdef HAVE_STRUCT_THREAD_TD_PCB

  /* In FreeBSD kernels for 5.0-RELEASE and later, the PCB no longer

     lives in `struct proc' but in `struct thread'.  The `struct

     thread' for the initial thread for proc0 can be found in the

     variable "thread0".  */

  memset (nl, 0, sizeof nl);

  nl[0].n_name = "_thread0";

  if (kvm_nlist (core_kd, nl) == -1)

    error (("%s"), kvm_geterr (core_kd));

  if (nl[0].n_value != 0)

    {

      struct pcb *paddr;

      /* Found thread0.  */

      nl[0].n_value += offsetof (struct thread, td_pcb);

      if (kvm_read (core_kd, nl[0].n_value, &paddr, sizeof paddr) == -1)

        error (("%s"), kvm_geterr (core_kd));

      bsd_kvm_fetch_pcb (regcache, paddr);

      return;

    }

#endif

  /* i18n: PCB == "Process Control Block" */

  error (_("Cannot find a valid PCB"));

}

/* Kernel memory interface commands.  */

struct cmd_list_element *bsd_kvm_cmdlist;

static void

bsd_kvm_cmd (char *arg, int fromtty)

{

  /* ??? Should this become an alias for "target kvm"?  */

}

#ifndef HAVE_STRUCT_THREAD_TD_PCB

static void

bsd_kvm_proc_cmd (char *arg, int fromtty)

{

  CORE_ADDR addr;

  if (arg == NULL)

    error_no_arg (_("proc address"));

  if (core_kd == NULL)

    error (_("No kernel memory image."));

  addr = parse_and_eval_address (arg);

#ifdef HAVE_STRUCT_LWP

  addr += offsetof (struct lwp, l_addr);

#else

  addr += offsetof (struct proc, p_addr);

#endif

  if (kvm_read (core_kd, addr, &bsd_kvm_paddr, sizeof bsd_kvm_paddr) == -1)

    error (("%s"), kvm_geterr (core_kd));

  target_fetch_registers (get_current_regcache (), -1);

  reinit_frame_cache ();

  print_stack_frame (get_selected_frame (NULL), -1, 1);

}

#endif

static void

bsd_kvm_pcb_cmd (char *arg, int fromtty)

{

  if (arg == NULL)

    /* i18n: PCB == "Process Control Block" */

    error_no_arg (_("pcb address"));

  if (core_kd == NULL)

    error (_("No kernel memory image."));

  bsd_kvm_paddr = (struct pcb *)(u_long) parse_and_eval_address (arg);

  target_fetch_registers (get_current_regcache (), -1);

  reinit_frame_cache ();

  print_stack_frame (get_selected_frame (NULL), -1, 1);

}

static int

bsd_kvm_thread_alive (struct target_ops *ops,

                      ptid_t ptid)

{

  return 1;

}

static char *

bsd_kvm_pid_to_str (struct target_ops *ops, ptid_t ptid)

{

  static char buf[64];

  xsnprintf (buf, sizeof buf, "<kvm>");

  return buf;

}

static int

bsd_kvm_return_one (struct target_ops *ops)

{

  return 1;

}

/* Add the libkvm interface to the list of all possible targets and

   register CUPPLY_PCB as the architecture-specific process control

   block interpreter.  */

void

bsd_kvm_add_target (int (*supply_pcb)(struct regcache *, struct pcb *))

{

  gdb_assert (bsd_kvm_supply_pcb == NULL);

  bsd_kvm_supply_pcb = supply_pcb;

  bsd_kvm_ops.to_shortname = "kvm";

  bsd_kvm_ops.to_longname = _("Kernel memory interface");

  bsd_kvm_ops.to_doc = _("Use a kernel virtual memory image as a target.\n\

Optionally specify the filename of a core dump.");

  bsd_kvm_ops.to_open = bsd_kvm_open;

  bsd_kvm_ops.to_close = bsd_kvm_close;

  bsd_kvm_ops.to_fetch_registers = bsd_kvm_fetch_registers;

  bsd_kvm_ops.to_xfer_partial = bsd_kvm_xfer_partial;

  bsd_kvm_ops.to_files_info = bsd_kvm_files_info;

  bsd_kvm_ops.to_thread_alive = bsd_kvm_thread_alive;

  bsd_kvm_ops.to_pid_to_str = bsd_kvm_pid_to_str;

  bsd_kvm_ops.to_stratum = process_stratum;

  bsd_kvm_ops.to_has_memory = bsd_kvm_return_one;

  bsd_kvm_ops.to_has_stack = bsd_kvm_return_one;

  bsd_kvm_ops.to_has_registers = bsd_kvm_return_one;

  bsd_kvm_ops.to_magic = OPS_MAGIC;

  add_target (&bsd_kvm_ops);

  add_prefix_cmd ("kvm", class_obscure, bsd_kvm_cmd, _("\

Generic command for manipulating the kernel memory interface."),

                  &bsd_kvm_cmdlist, "kvm ", 0, &cmdlist);

#ifndef HAVE_STRUCT_THREAD_TD_PCB

  add_cmd ("proc", class_obscure, bsd_kvm_proc_cmd,

           _("Set current context from proc address"), &bsd_kvm_cmdlist);

#endif

  add_cmd ("pcb", class_obscure, bsd_kvm_pcb_cmd,

           /* i18n: PCB == "Process Control Block" */

           _("Set current context from pcb address"), &bsd_kvm_cmdlist);

  /* Some notes on the ptid usage on this target.

     The pid field represents the kvm inferior instance.  Currently,

     we don't support multiple kvm inferiors, but we start at 1

     anyway.  The lwp field is set to != 0, in case the core wants to

     refer to the whole kvm inferior with ptid(1,0,0).

     If kvm is made to export running processes as gdb threads,

     the following form can be used:

     ptid (1, 1, 0) -> kvm inferior 1, in kernel

     ptid (1, 1, 1) -> kvm inferior 1, process 1

     ptid (1, 1, 2) -> kvm inferior 1, process 2

     ptid (1, 1, n) -> kvm inferior 1, process n

  */

  bsd_kvm_ptid = ptid_build (1, 1, 0);

}