1/* BSD Kernel Data Access Library (libkvm) interface.
2
3   Copyright (C) 2004, 2005, 2007 Free Software Foundation, Inc.
4
5   This file is part of GDB.
6
7   This program is free software; you can redistribute it and/or modify
8   it under the terms of the GNU General Public License as published by
9   the Free Software Foundation; either version 3 of the License, or
10   (at your option) any later version.
11
12   This program is distributed in the hope that it will be useful,
13   but WITHOUT ANY WARRANTY; without even the implied warranty of
14   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15   GNU General Public License for more details.
16
17   You should have received a copy of the GNU General Public License
18   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
19
20#include "defs.h"
21#include "cli/cli-cmds.h"
22#include "command.h"
23#include "frame.h"
24#include "regcache.h"
25#include "target.h"
26#include "value.h"
27#include "gdbcore.h"		/* for get_exec_file */
28
29#include "gdb_assert.h"
30#include <fcntl.h>
31#include <kvm.h>
32#ifdef HAVE_NLIST_H
33#include <nlist.h>
34#endif
35#include <paths.h>
36#include "readline/readline.h"
37#include <sys/param.h>
38#include <sys/proc.h>
39#include <sys/user.h>
40
41#include "bsd-kvm.h"
42
43/* Kernel memory device file.  */
44static const char *bsd_kvm_corefile;
45
46/* Kernel memory interface descriptor.  */
47static kvm_t *core_kd;
48
49/* Address of process control block.  */
50static struct pcb *bsd_kvm_paddr;
51
52/* Pointer to architecture-specific function that reconstructs the
53   register state from PCB and supplies it to REGCACHE.  */
54static int (*bsd_kvm_supply_pcb)(struct regcache *regcache, struct pcb *pcb);
55
56/* Target ops for libkvm interface.  */
57static struct target_ops bsd_kvm_ops;
58
59static void
60bsd_kvm_open (char *filename, int from_tty)
61{
62  char errbuf[_POSIX2_LINE_MAX];
63  char *execfile = NULL;
64  kvm_t *temp_kd;
65
66  target_preopen (from_tty);
67
68  if (filename)
69    {
70      char *temp;
71
72      filename = tilde_expand (filename);
73      if (filename[0] != '/')
74	{
75	  temp = concat (current_directory, "/", filename, (char *)NULL);
76	  xfree (filename);
77	  filename = temp;
78	}
79    }
80
81  execfile = get_exec_file (0);
82  temp_kd = kvm_openfiles (execfile, filename, NULL,
83			   write_files ? O_RDWR : O_RDONLY, errbuf);
84  if (temp_kd == NULL)
85    error (("%s"), errbuf);
86
87  bsd_kvm_corefile = filename;
88  unpush_target (&bsd_kvm_ops);
89  core_kd = temp_kd;
90  push_target (&bsd_kvm_ops);
91
92  target_fetch_registers (get_current_regcache (), -1);
93
94  reinit_frame_cache ();
95  print_stack_frame (get_selected_frame (NULL), -1, 1);
96}
97
98static void
99bsd_kvm_close (int quitting)
100{
101  if (core_kd)
102    {
103      if (kvm_close (core_kd) == -1)
104	warning (("%s"), kvm_geterr(core_kd));
105      core_kd = NULL;
106    }
107}
108
109static LONGEST
110bsd_kvm_xfer_memory (CORE_ADDR addr, ULONGEST len,
111		     gdb_byte *readbuf, const gdb_byte *writebuf)
112{
113  ssize_t nbytes = len;
114
115  if (readbuf)
116    nbytes = kvm_read (core_kd, addr, readbuf, nbytes);
117  if (writebuf && nbytes > 0)
118    nbytes = kvm_write (core_kd, addr, writebuf, nbytes);
119  return nbytes;
120}
121
122static LONGEST
123bsd_kvm_xfer_partial (struct target_ops *ops, enum target_object object,
124		      const char *annex, gdb_byte *readbuf,
125		      const gdb_byte *writebuf,
126		      ULONGEST offset, LONGEST len)
127{
128  switch (object)
129    {
130    case TARGET_OBJECT_MEMORY:
131      return bsd_kvm_xfer_memory (offset, len, readbuf, writebuf);
132
133    default:
134      return -1;
135    }
136}
137
138static void
139bsd_kvm_files_info (struct target_ops *ops)
140{
141  if (bsd_kvm_corefile && strcmp (bsd_kvm_corefile, _PATH_MEM) != 0)
142    printf_filtered (_("\tUsing the kernel crash dump %s.\n"),
143		     bsd_kvm_corefile);
144  else
145    printf_filtered (_("\tUsing the currently running kernel.\n"));
146}
147
148/* Fetch process control block at address PADDR.  */
149
150static int
151bsd_kvm_fetch_pcb (struct regcache *regcache, struct pcb *paddr)
152{
153  struct pcb pcb;
154
155  if (kvm_read (core_kd, (unsigned long) paddr, &pcb, sizeof pcb) == -1)
156    error (("%s"), kvm_geterr (core_kd));
157
158  gdb_assert (bsd_kvm_supply_pcb);
159  return bsd_kvm_supply_pcb (regcache, &pcb);
160}
161
162static void
163bsd_kvm_fetch_registers (struct regcache *regcache, int regnum)
164{
165  struct nlist nl[2];
166
167  if (bsd_kvm_paddr)
168    {
169      bsd_kvm_fetch_pcb (regcache, bsd_kvm_paddr);
170      return;
171    }
172
173  /* On dumping core, BSD kernels store the faulting context (PCB)
174     in the variable "dumppcb".  */
175  memset (nl, 0, sizeof nl);
176  nl[0].n_name = "_dumppcb";
177
178  if (kvm_nlist (core_kd, nl) == -1)
179    error (("%s"), kvm_geterr (core_kd));
180
181  if (nl[0].n_value != 0)
182    {
183      /* Found dumppcb. If it contains a valid context, return
184	 immediately.  */
185      if (bsd_kvm_fetch_pcb (regcache, (struct pcb *) nl[0].n_value))
186	return;
187    }
188
189  /* Traditional BSD kernels have a process proc0 that should always
190     be present.  The address of proc0's PCB is stored in the variable
191     "proc0paddr".  */
192
193  memset (nl, 0, sizeof nl);
194  nl[0].n_name = "_proc0paddr";
195
196  if (kvm_nlist (core_kd, nl) == -1)
197    error (("%s"), kvm_geterr (core_kd));
198
199  if (nl[0].n_value != 0)
200    {
201      struct pcb *paddr;
202
203      /* Found proc0paddr.  */
204      if (kvm_read (core_kd, nl[0].n_value, &paddr, sizeof paddr) == -1)
205	error (("%s"), kvm_geterr (core_kd));
206
207      bsd_kvm_fetch_pcb (regcache, paddr);
208      return;
209    }
210
211#ifdef HAVE_STRUCT_THREAD_TD_PCB
212  /* In FreeBSD kernels for 5.0-RELEASE and later, the PCB no longer
213     lives in `struct proc' but in `struct thread'.  The `struct
214     thread' for the initial thread for proc0 can be found in the
215     variable "thread0".  */
216
217  memset (nl, 0, sizeof nl);
218  nl[0].n_name = "_thread0";
219
220  if (kvm_nlist (core_kd, nl) == -1)
221    error (("%s"), kvm_geterr (core_kd));
222
223  if (nl[0].n_value != 0)
224    {
225      struct pcb *paddr;
226
227      /* Found thread0.  */
228      nl[0].n_value += offsetof (struct thread, td_pcb);
229      if (kvm_read (core_kd, nl[0].n_value, &paddr, sizeof paddr) == -1)
230	error (("%s"), kvm_geterr (core_kd));
231
232      bsd_kvm_fetch_pcb (regcache, paddr);
233      return;
234    }
235#endif
236
237  /* i18n: PCB == "Process Control Block" */
238  error (_("Cannot find a valid PCB"));
239}
240
241
242/* Kernel memory interface commands.  */
243struct cmd_list_element *bsd_kvm_cmdlist;
244
245static void
246bsd_kvm_cmd (char *arg, int fromtty)
247{
248  /* ??? Should this become an alias for "target kvm"?  */
249}
250
251#ifndef HAVE_STRUCT_THREAD_TD_PCB
252
253static void
254bsd_kvm_proc_cmd (char *arg, int fromtty)
255{
256  CORE_ADDR addr;
257
258  if (arg == NULL)
259    error_no_arg (_("proc address"));
260
261  if (core_kd == NULL)
262    error (_("No kernel memory image."));
263
264  addr = parse_and_eval_address (arg);
265#ifdef HAVE_STRUCT_LWP
266  addr += offsetof (struct lwp, l_addr);
267#else
268  addr += offsetof (struct proc, p_addr);
269#endif
270
271  if (kvm_read (core_kd, addr, &bsd_kvm_paddr, sizeof bsd_kvm_paddr) == -1)
272    error (("%s"), kvm_geterr (core_kd));
273
274  target_fetch_registers (get_current_regcache (), -1);
275
276  reinit_frame_cache ();
277  print_stack_frame (get_selected_frame (NULL), -1, 1);
278}
279
280#endif
281
282static void
283bsd_kvm_pcb_cmd (char *arg, int fromtty)
284{
285  if (arg == NULL)
286    /* i18n: PCB == "Process Control Block" */
287    error_no_arg (_("pcb address"));
288
289  if (core_kd == NULL)
290    error (_("No kernel memory image."));
291
292  bsd_kvm_paddr = (struct pcb *)(u_long) parse_and_eval_address (arg);
293
294  target_fetch_registers (get_current_regcache (), -1);
295
296  reinit_frame_cache ();
297  print_stack_frame (get_selected_frame (NULL), -1, 1);
298}
299
300/* Add the libkvm interface to the list of all possible targets and
301   register CUPPLY_PCB as the architecture-specific process control
302   block interpreter.  */
303
304void
305bsd_kvm_add_target (int (*supply_pcb)(struct regcache *, struct pcb *))
306{
307  gdb_assert (bsd_kvm_supply_pcb == NULL);
308  bsd_kvm_supply_pcb = supply_pcb;
309
310  bsd_kvm_ops.to_shortname = "kvm";
311  bsd_kvm_ops.to_longname = _("Kernel memory interface");
312  bsd_kvm_ops.to_doc = _("Use a kernel virtual memory image as a target.\n\
313Optionally specify the filename of a core dump.");
314  bsd_kvm_ops.to_open = bsd_kvm_open;
315  bsd_kvm_ops.to_close = bsd_kvm_close;
316  bsd_kvm_ops.to_fetch_registers = bsd_kvm_fetch_registers;
317  bsd_kvm_ops.to_xfer_partial = bsd_kvm_xfer_partial;
318  bsd_kvm_ops.to_files_info = bsd_kvm_files_info;
319  bsd_kvm_ops.to_stratum = process_stratum;
320  bsd_kvm_ops.to_has_memory = 1;
321  bsd_kvm_ops.to_has_stack = 1;
322  bsd_kvm_ops.to_has_registers = 1;
323  bsd_kvm_ops.to_magic = OPS_MAGIC;
324
325  add_target (&bsd_kvm_ops);
326
327  add_prefix_cmd ("kvm", class_obscure, bsd_kvm_cmd, _("\
328Generic command for manipulating the kernel memory interface."),
329		  &bsd_kvm_cmdlist, "kvm ", 0, &cmdlist);
330
331#ifndef HAVE_STRUCT_THREAD_TD_PCB
332  add_cmd ("proc", class_obscure, bsd_kvm_proc_cmd,
333	   _("Set current context from proc address"), &bsd_kvm_cmdlist);
334#endif
335  add_cmd ("pcb", class_obscure, bsd_kvm_pcb_cmd,
336	   /* i18n: PCB == "Process Control Block" */
337	   _("Set current context from pcb address"), &bsd_kvm_cmdlist);
338}
339