gdb/bsd-kvm.c

   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 2 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, write to the Free Software
  19    Foundation, Inc., 51 Franklin Street, Fifth Floor,
  20    Boston, MA 02110-1301, USA.  */
  21
  22 #include "defs.h"
  23 #include "cli/cli-cmds.h"
  24 #include "command.h"
  25 #include "frame.h"
  26 #include "regcache.h"
  27 #include "target.h"
  28 #include "value.h"
  29 #include "gdbcore.h"            /* for get_exec_file */
  30
  31 #include "gdb_assert.h"
  32 #include <fcntl.h>
  33 #include <kvm.h>
  34 #ifdef HAVE_NLIST_H
  35 #include <nlist.h>
  36 #endif
  37 #include <paths.h>
  38 #include "readline/readline.h"
  39 #include <sys/param.h>
  40 #include <sys/proc.h>
  41 #include <sys/user.h>
  42
  43 #include "bsd-kvm.h"
  44
  45 /* Kernel memory device file.  */
  46 static const char *bsd_kvm_corefile;
  47
  48 /* Kernel memory interface descriptor.  */
  49 static kvm_t *core_kd;
  50
  51 /* Address of process control block.  */
  52 static struct pcb *bsd_kvm_paddr;
  53
  54 /* Pointer to architecture-specific function that reconstructs the
  55    register state from PCB and supplies it to REGCACHE.  */
  56 static int (*bsd_kvm_supply_pcb)(struct regcache *regcache, struct pcb *pcb);
  57
  58 /* Target ops for libkvm interface.  */
  59 static struct target_ops bsd_kvm_ops;
  60
  61 static void
  62 bsd_kvm_open (char *filename, int from_tty)
  63 {
  64   char errbuf[_POSIX2_LINE_MAX];
  65   char *execfile = NULL;
  66   kvm_t *temp_kd;
  67
  68   target_preopen (from_tty);
  69
  70   if (filename)
  71     {
  72       char *temp;
  73
  74       filename = tilde_expand (filename);
  75       if (filename[0] != '/')
  76         {
  77           temp = concat (current_directory, "/", filename, (char *)NULL);
  78           xfree (filename);
  79           filename = temp;
  80         }
  81     }
  82
  83   execfile = get_exec_file (0);
  84   temp_kd = kvm_openfiles (execfile, filename, NULL,
  85                            write_files ? O_RDWR : O_RDONLY, errbuf);
  86   if (temp_kd == NULL)
  87     error (("%s"), errbuf);
  88
  89   bsd_kvm_corefile = filename;
  90   unpush_target (&bsd_kvm_ops);
  91   core_kd = temp_kd;
  92   push_target (&bsd_kvm_ops);
  93
  94   target_fetch_registers (get_current_regcache (), -1);
  95
  96   reinit_frame_cache ();
  97   print_stack_frame (get_selected_frame (NULL), -1, 1);
  98 }
  99
 100 static void
 101 bsd_kvm_close (int quitting)
 102 {
 103   if (core_kd)
 104     {
 105       if (kvm_close (core_kd) == -1)
 106         warning (("%s"), kvm_geterr(core_kd));
 107       core_kd = NULL;
 108     }
 109 }
 110
 111 static LONGEST
 112 bsd_kvm_xfer_memory (CORE_ADDR addr, ULONGEST len,
 113                      gdb_byte *readbuf, const gdb_byte *writebuf)
 114 {
 115   ssize_t nbytes = len;
 116
 117   if (readbuf)
 118     nbytes = kvm_read (core_kd, addr, readbuf, nbytes);
 119   if (writebuf && nbytes > 0)
 120     nbytes = kvm_write (core_kd, addr, writebuf, nbytes);
 121   return nbytes;
 122 }
 123
 124 static LONGEST
 125 bsd_kvm_xfer_partial (struct target_ops *ops, enum target_object object,
 126                       const char *annex, gdb_byte *readbuf,
 127                       const gdb_byte *writebuf,
 128                       ULONGEST offset, LONGEST len)
 129 {
 130   switch (object)
 131     {
 132     case TARGET_OBJECT_MEMORY:
 133       return bsd_kvm_xfer_memory (offset, len, readbuf, writebuf);
 134
 135     default:
 136       return -1;
 137     }
 138 }
 139
 140 static void
 141 bsd_kvm_files_info (struct target_ops *ops)
 142 {
 143   if (bsd_kvm_corefile && strcmp (bsd_kvm_corefile, _PATH_MEM) != 0)
 144     printf_filtered (_("\tUsing the kernel crash dump %s.\n"),
 145                      bsd_kvm_corefile);
 146   else
 147     printf_filtered (_("\tUsing the currently running kernel.\n"));
 148 }
 149
 150 /* Fetch process control block at address PADDR.  */
 151
 152 static int
 153 bsd_kvm_fetch_pcb (struct regcache *regcache, struct pcb *paddr)
 154 {
 155   struct pcb pcb;
 156
 157   if (kvm_read (core_kd, (unsigned long) paddr, &pcb, sizeof pcb) == -1)
 158     error (("%s"), kvm_geterr (core_kd));
 159
 160   gdb_assert (bsd_kvm_supply_pcb);
 161   return bsd_kvm_supply_pcb (regcache, &pcb);
 162 }
 163
 164 static void
 165 bsd_kvm_fetch_registers (struct regcache *regcache, int regnum)
 166 {
 167   struct nlist nl[2];
 168
 169   if (bsd_kvm_paddr)
 170     {
 171       bsd_kvm_fetch_pcb (regcache, bsd_kvm_paddr);
 172       return;
 173     }
 174
 175   /* On dumping core, BSD kernels store the faulting context (PCB)
 176      in the variable "dumppcb".  */
 177   memset (nl, 0, sizeof nl);
 178   nl[0].n_name = "_dumppcb";
 179
 180   if (kvm_nlist (core_kd, nl) == -1)
 181     error (("%s"), kvm_geterr (core_kd));
 182
 183   if (nl[0].n_value != 0)
 184     {
 185       /* Found dumppcb. If it contains a valid context, return
 186          immediately.  */
 187       if (bsd_kvm_fetch_pcb (regcache, (struct pcb *) nl[0].n_value))
 188         return;
 189     }
 190
 191   /* Traditional BSD kernels have a process proc0 that should always
 192      be present.  The address of proc0's PCB is stored in the variable
 193      "proc0paddr".  */
 194
 195   memset (nl, 0, sizeof nl);
 196   nl[0].n_name = "_proc0paddr";
 197
 198   if (kvm_nlist (core_kd, nl) == -1)
 199     error (("%s"), kvm_geterr (core_kd));
 200
 201   if (nl[0].n_value != 0)
 202     {
 203       struct pcb *paddr;
 204
 205       /* Found proc0paddr.  */
 206       if (kvm_read (core_kd, nl[0].n_value, &paddr, sizeof paddr) == -1)
 207         error (("%s"), kvm_geterr (core_kd));
 208
 209       bsd_kvm_fetch_pcb (regcache, paddr);
 210       return;
 211     }
 212
 213 #ifdef HAVE_STRUCT_THREAD_TD_PCB
 214   /* In FreeBSD kernels for 5.0-RELEASE and later, the PCB no longer
 215      lives in `struct proc' but in `struct thread'.  The `struct
 216      thread' for the initial thread for proc0 can be found in the
 217      variable "thread0".  */
 218
 219   memset (nl, 0, sizeof nl);
 220   nl[0].n_name = "_thread0";
 221
 222   if (kvm_nlist (core_kd, nl) == -1)
 223     error (("%s"), kvm_geterr (core_kd));
 224
 225   if (nl[0].n_value != 0)
 226     {
 227       struct pcb *paddr;
 228
 229       /* Found thread0.  */
 230       nl[0].n_value += offsetof (struct thread, td_pcb);
 231       if (kvm_read (core_kd, nl[0].n_value, &paddr, sizeof paddr) == -1)
 232         error (("%s"), kvm_geterr (core_kd));
 233
 234       bsd_kvm_fetch_pcb (regcache, paddr);
 235       return;
 236     }
 237 #endif
 238
 239   /* i18n: PCB == "Process Control Block" */
 240   error (_("Cannot find a valid PCB"));
 241 }
 242 \f
 243
 244 /* Kernel memory interface commands.  */
 245 struct cmd_list_element *bsd_kvm_cmdlist;
 246
 247 static void
 248 bsd_kvm_cmd (char *arg, int fromtty)
 249 {
 250   /* ??? Should this become an alias for "target kvm"?  */
 251 }
 252
 253 #ifndef HAVE_STRUCT_THREAD_TD_PCB
 254
 255 static void
 256 bsd_kvm_proc_cmd (char *arg, int fromtty)
 257 {
 258   CORE_ADDR addr;
 259
 260   if (arg == NULL)
 261     error_no_arg (_("proc address"));
 262
 263   if (core_kd == NULL)
 264     error (_("No kernel memory image."));
 265
 266   addr = parse_and_eval_address (arg);
 267 #ifdef HAVE_STRUCT_LWP
 268   addr += offsetof (struct lwp, l_addr);
 269 #else
 270   addr += offsetof (struct proc, p_addr);
 271 #endif
 272
 273   if (kvm_read (core_kd, addr, &bsd_kvm_paddr, sizeof bsd_kvm_paddr) == -1)
 274     error (("%s"), kvm_geterr (core_kd));
 275
 276   target_fetch_registers (get_current_regcache (), -1);
 277
 278   reinit_frame_cache ();
 279   print_stack_frame (get_selected_frame (NULL), -1, 1);
 280 }
 281
 282 #endif
 283
 284 static void
 285 bsd_kvm_pcb_cmd (char *arg, int fromtty)
 286 {
 287   if (arg == NULL)
 288     /* i18n: PCB == "Process Control Block" */
 289     error_no_arg (_("pcb address"));
 290
 291   if (core_kd == NULL)
 292     error (_("No kernel memory image."));
 293
 294   bsd_kvm_paddr = (struct pcb *)(u_long) parse_and_eval_address (arg);
 295
 296   target_fetch_registers (get_current_regcache (), -1);
 297
 298   reinit_frame_cache ();
 299   print_stack_frame (get_selected_frame (NULL), -1, 1);
 300 }
 301
 302 /* Add the libkvm interface to the list of all possible targets and
 303    register CUPPLY_PCB as the architecture-specific process control
 304    block interpreter.  */
 305
 306 void
 307 bsd_kvm_add_target (int (*supply_pcb)(struct regcache *, struct pcb *))
 308 {
 309   gdb_assert (bsd_kvm_supply_pcb == NULL);
 310   bsd_kvm_supply_pcb = supply_pcb;
 311
 312   bsd_kvm_ops.to_shortname = "kvm";
 313   bsd_kvm_ops.to_longname = _("Kernel memory interface");
 314   bsd_kvm_ops.to_doc = _("Use a kernel virtual memory image as a target.\n\
 315 Optionally specify the filename of a core dump.");
 316   bsd_kvm_ops.to_open = bsd_kvm_open;
 317   bsd_kvm_ops.to_close = bsd_kvm_close;
 318   bsd_kvm_ops.to_fetch_registers = bsd_kvm_fetch_registers;
 319   bsd_kvm_ops.to_xfer_partial = bsd_kvm_xfer_partial;
 320   bsd_kvm_ops.to_files_info = bsd_kvm_files_info;
 321   bsd_kvm_ops.to_stratum = process_stratum;
 322   bsd_kvm_ops.to_has_memory = 1;
 323   bsd_kvm_ops.to_has_stack = 1;
 324   bsd_kvm_ops.to_has_registers = 1;
 325   bsd_kvm_ops.to_magic = OPS_MAGIC;
 326
 327   add_target (&bsd_kvm_ops);
 328
 329   add_prefix_cmd ("kvm", class_obscure, bsd_kvm_cmd, _("\
 330 Generic command for manipulating the kernel memory interface."),
 331                   &bsd_kvm_cmdlist, "kvm ", 0, &cmdlist);
 332
 333 #ifndef HAVE_STRUCT_THREAD_TD_PCB
 334   add_cmd ("proc", class_obscure, bsd_kvm_proc_cmd,
 335            _("Set current context from proc address"), &bsd_kvm_cmdlist);
 336 #endif
 337   add_cmd ("pcb", class_obscure, bsd_kvm_pcb_cmd,
 338            /* i18n: PCB == "Process Control Block" */
 339            _("Set current context from pcb address"), &bsd_kvm_cmdlist);
 340 }