aboutsummaryrefslogtreecommitdiff
path: root/gdb/bsd-kvm.c
blob: 30434a9e11fd2d2aa8434fb02db3b0b370191c8d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
/* BSD Kernel Data Access Library (libkvm) interface.

   Copyright (C) 2004-2014 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 <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 (const char *arg, int from_tty)
{
  char errbuf[_POSIX2_LINE_MAX];
  char *execfile = NULL;
  kvm_t *temp_kd;
  char *filename = NULL;

  target_preopen (from_tty);

  if (arg)
    {
      char *temp;

      filename = tilde_expand (arg);
      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), 0, SRC_AND_LOC, 1);
}

static void
bsd_kvm_close (struct target_ops *self)
{
  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 enum target_xfer_status
bsd_kvm_xfer_partial (struct target_ops *ops, enum target_object object,
		      const char *annex, gdb_byte *readbuf,
		      const gdb_byte *writebuf,
		      ULONGEST offset, ULONGEST len, ULONGEST *xfered_len)
{
  switch (object)
    {
    case TARGET_OBJECT_MEMORY:
      {
	LONGEST ret = bsd_kvm_xfer_memory (offset, len, readbuf, writebuf);

	if (ret < 0)
	  return TARGET_XFER_E_IO;
	else if (ret == 0)
	  return TARGET_XFER_EOF;
	else
	  {
	    *xfered_len = (ULONGEST) ret;
	    return TARGET_XFER_OK;
	  }
      }

    default:
      return TARGET_XFER_E_IO;
    }
}

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), 0, SRC_AND_LOC, 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), 0, SRC_AND_LOC, 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);
}