gdb/bsd-kvm.c

   1 /* BSD Kernel Data Access Library (libkvm) interface.
   2
   3    Copyright (C) 2004, 2005, 2007, 2008 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.  */
  44 static const char *bsd_kvm_corefile;
  45
  46 /* Kernel memory interface descriptor.  */
  47 static kvm_t *core_kd;
  48
  49 /* Address of process control block.  */
  50 static 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.  */
  54 static int (*bsd_kvm_supply_pcb)(struct regcache *regcache, struct pcb *pcb);
  55
  56 /* Target ops for libkvm interface.  */
  57 static struct target_ops bsd_kvm_ops;
  58
  59 static void
  60 bsd_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
  98 static void
  99 bsd_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
 109 static LONGEST
 110 bsd_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
 122 static LONGEST
 123 bsd_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
 138 static void
 139 bsd_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
 150 static int
 151 bsd_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
 162 static void
 163 bsd_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 \f
 241
 242 /* Kernel memory interface commands.  */
 243 struct cmd_list_element *bsd_kvm_cmdlist;
 244
 245 static void
 246 bsd_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
 253 static void
 254 bsd_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
 282 static void
 283 bsd_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
 304 void
 305 bsd_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\
 313 Optionally 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, _("\
 328 Generic 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 }