gdb/bsd-kvm.c

   1 /* BSD Kernel Data Access Library (libkvm) interface.
   2
   3    Copyright 2004, 2005 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., 59 Temple Place - Suite 330,
  20    Boston, MA 02111-1307, 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 "readline/readline.h"
  38 #include <sys/param.h>
  39 #include <sys/proc.h>
  40 #include <sys/user.h>
  41
  42 #include "bsd-kvm.h"
  43
  44 /* Kernel memory interface descriptor.  */
  45 kvm_t *core_kd;
  46
  47 /* Address of process control block.  */
  48 struct pcb *bsd_kvm_paddr;
  49
  50 /* Pointer to architecture-specific function that reconstructs the
  51    register state from PCB and supplies it to REGCACHE.  */
  52 int (*bsd_kvm_supply_pcb)(struct regcache *regcache, struct pcb *pcb);
  53
  54 /* Target ops for libkvm interface.  */
  55 struct target_ops bsd_kvm_ops;
  56
  57 static void
  58 bsd_kvm_open (char *filename, int from_tty)
  59 {
  60   char errbuf[_POSIX2_LINE_MAX];
  61   char *execfile = NULL;
  62   kvm_t *temp_kd;
  63
  64   target_preopen (from_tty);
  65
  66   if (filename)
  67     {
  68       char *temp;
  69
  70       filename = tilde_expand (filename);
  71       if (filename[0] != '/')
  72         {
  73           temp = concat (current_directory, "/", filename, NULL);
  74           xfree (filename);
  75           filename = temp;
  76         }
  77     }
  78
  79   execfile = get_exec_file (0);
  80   temp_kd = kvm_openfiles (execfile, filename, NULL, O_RDONLY, errbuf);
  81   if (temp_kd == NULL)
  82     error (("%s"), errbuf);
  83
  84   unpush_target (&bsd_kvm_ops);
  85   core_kd = temp_kd;
  86   push_target (&bsd_kvm_ops);
  87
  88   target_fetch_registers (-1);
  89
  90   flush_cached_frames ();
  91   select_frame (get_current_frame ());
  92   print_stack_frame (get_selected_frame (NULL), -1, 1);
  93 }
  94
  95 static void
  96 bsd_kvm_close (int quitting)
  97 {
  98   if (core_kd)
  99     {
 100       if (kvm_close (core_kd) == -1)
 101         warning (("%s"), kvm_geterr(core_kd));
 102       core_kd = NULL;
 103     }
 104 }
 105
 106 static LONGEST
 107 bsd_kvm_xfer_memory (CORE_ADDR addr, ULONGEST len,
 108                      gdb_byte *readbuf, const gdb_byte *writebuf)
 109 {
 110   ssize_t nbytes = len;
 111
 112   if (readbuf)
 113     nbytes = kvm_read (core_kd, addr, readbuf, nbytes);
 114   if (writebuf && nbytes > 0)
 115     nbytes = kvm_write (core_kd, addr, writebuf, nbytes);
 116   return nbytes;
 117 }
 118
 119 static LONGEST
 120 bsd_kvm_xfer_partial (struct target_ops *ops, enum target_object object,
 121                       const char *annex, gdb_byte *readbuf,
 122                       const gdb_byte *writebuf,
 123                       ULONGEST offset, LONGEST len)
 124 {
 125   switch (object)
 126     {
 127     case TARGET_OBJECT_MEMORY:
 128       return bsd_kvm_xfer_memory (offset, len, readbuf, writebuf);
 129
 130     default:
 131       return -1;
 132     }
 133 }
 134
 135 /* Fetch process control block at address PADDR.  */
 136
 137 static int
 138 bsd_kvm_fetch_pcb (struct pcb *paddr)
 139 {
 140   struct pcb pcb;
 141
 142   if (kvm_read (core_kd, (unsigned long) paddr, &pcb, sizeof pcb) == -1)
 143     error (("%s"), kvm_geterr (core_kd));
 144
 145   gdb_assert (bsd_kvm_supply_pcb);
 146   return bsd_kvm_supply_pcb (current_regcache, &pcb);
 147 }
 148
 149 static void
 150 bsd_kvm_fetch_registers (int regnum)
 151 {
 152   struct nlist nl[2];
 153
 154   if (bsd_kvm_paddr)
 155     {
 156       bsd_kvm_fetch_pcb (bsd_kvm_paddr);
 157       return;
 158     }
 159
 160   /* On dumping core, BSD kernels store the faulting context (PCB)
 161      in the variable "dumppcb".  */
 162   memset (nl, 0, sizeof nl);
 163   nl[0].n_name = "_dumppcb";
 164
 165   if (kvm_nlist (core_kd, nl) == -1)
 166     error (("%s"), kvm_geterr (core_kd));
 167
 168   if (nl[0].n_value != 0)
 169     {
 170       /* Found dumppcb. If it contains a valid context, return
 171          immediately.  */
 172       if (bsd_kvm_fetch_pcb ((struct pcb *) nl[0].n_value))
 173         return;
 174     }
 175
 176   /* Traditional BSD kernels have a process proc0 that should always
 177      be present.  The address of proc0's PCB is stored in the variable
 178      "proc0paddr".  */
 179
 180   memset (nl, 0, sizeof nl);
 181   nl[0].n_name = "_proc0paddr";
 182
 183   if (kvm_nlist (core_kd, nl) == -1)
 184     error (("%s"), kvm_geterr (core_kd));
 185
 186   if (nl[0].n_value != 0)
 187     {
 188       struct pcb *paddr;
 189
 190       /* Found proc0paddr.  */
 191       if (kvm_read (core_kd, nl[0].n_value, &paddr, sizeof paddr) == -1)
 192         error (("%s"), kvm_geterr (core_kd));
 193
 194       bsd_kvm_fetch_pcb (paddr);
 195       return;
 196     }
 197
 198 #ifdef HAVE_STRUCT_THREAD_TD_PCB
 199   /* In FreeBSD kernels for 5.0-RELEASE and later, the PCB no longer
 200      lives in `struct proc' but in `struct thread'.  The `struct
 201      thread' for the initial thread for proc0 can be found in the
 202      variable "thread0".  */
 203
 204   memset (nl, 0, sizeof nl);
 205   nl[0].n_name = "_thread0";
 206
 207   if (kvm_nlist (core_kd, nl) == -1)
 208     error (("%s"), kvm_geterr (core_kd));
 209
 210   if (nl[0].n_value != 0)
 211     {
 212       struct pcb *paddr;
 213
 214       /* Found thread0.  */
 215       nl[0].n_value += offsetof (struct thread, td_pcb);
 216       if (kvm_read (core_kd, nl[0].n_value, &paddr, sizeof paddr) == -1)
 217         error (("%s"), kvm_geterr (core_kd));
 218
 219       bsd_kvm_fetch_pcb (paddr);
 220       return;
 221     }
 222 #endif
 223
 224   /* i18n: PCB == "Process Control Block" */
 225   error (_("Cannot find a valid PCB"));
 226 }
 227 \f
 228
 229 /* Kernel memory interface commands.  */
 230 struct cmd_list_element *bsd_kvm_cmdlist;
 231
 232 static void
 233 bsd_kvm_cmd (char *arg, int fromtty)
 234 {
 235   /* ??? Should this become an alias for "target kvm"?  */
 236 }
 237
 238 #ifndef HAVE_STRUCT_THREAD_TD_PCB
 239
 240 static void
 241 bsd_kvm_proc_cmd (char *arg, int fromtty)
 242 {
 243   CORE_ADDR addr;
 244
 245   if (arg == NULL)
 246     error_no_arg (_("proc address"));
 247
 248   if (core_kd == NULL)
 249     error (_("No kernel memory image."));
 250
 251   addr = parse_and_eval_address (arg);
 252 #ifdef HAVE_STRUCT_LWP
 253   addr += offsetof (struct lwp, l_addr);
 254 #else
 255   addr += offsetof (struct proc, p_addr);
 256 #endif
 257
 258   if (kvm_read (core_kd, addr, &bsd_kvm_paddr, sizeof bsd_kvm_paddr) == -1)
 259     error (("%s"), kvm_geterr (core_kd));
 260
 261   target_fetch_registers (-1);
 262
 263   flush_cached_frames ();
 264   select_frame (get_current_frame ());
 265   print_stack_frame (get_selected_frame (NULL), -1, 1);
 266 }
 267
 268 #endif
 269
 270 static void
 271 bsd_kvm_pcb_cmd (char *arg, int fromtty)
 272 {
 273   if (arg == NULL)
 274     /* i18n: PCB == "Process Control Block" */
 275     error_no_arg (_("pcb address"));
 276
 277   if (core_kd == NULL)
 278     error (_("No kernel memory image."));
 279
 280   bsd_kvm_paddr = (struct pcb *)(u_long) parse_and_eval_address (arg);
 281
 282   target_fetch_registers (-1);
 283
 284   flush_cached_frames ();
 285   select_frame (get_current_frame ());
 286   print_stack_frame (get_selected_frame (NULL), -1, 1);
 287 }
 288
 289 /* Add the libkvm interface to the list of all possible targets and
 290    register CUPPLY_PCB as the architecture-specific process control
 291    block interpreter.  */
 292
 293 void
 294 bsd_kvm_add_target (int (*supply_pcb)(struct regcache *, struct pcb *))
 295 {
 296   gdb_assert (bsd_kvm_supply_pcb == NULL);
 297   bsd_kvm_supply_pcb = supply_pcb;
 298
 299   bsd_kvm_ops.to_shortname = "kvm";
 300   bsd_kvm_ops.to_longname = _("Kernel memory interface");
 301   bsd_kvm_ops.to_doc = _("Use a kernel virtual memory image as a target.\n\
 302 Optionally specify the filename of a core dump.");
 303   bsd_kvm_ops.to_open = bsd_kvm_open;
 304   bsd_kvm_ops.to_close = bsd_kvm_close;
 305   bsd_kvm_ops.to_fetch_registers = bsd_kvm_fetch_registers;
 306   bsd_kvm_ops.to_xfer_partial = bsd_kvm_xfer_partial;
 307   bsd_kvm_ops.to_stratum = process_stratum;
 308   bsd_kvm_ops.to_has_memory = 1;
 309   bsd_kvm_ops.to_has_stack = 1;
 310   bsd_kvm_ops.to_has_registers = 1;
 311   bsd_kvm_ops.to_magic = OPS_MAGIC;
 312
 313   add_target (&bsd_kvm_ops);
 314
 315   add_prefix_cmd ("kvm", class_obscure, bsd_kvm_cmd, _("\
 316 Generic command for manipulating the kernel memory interface."),
 317                   &bsd_kvm_cmdlist, "kvm ", 0, &cmdlist);
 318
 319 #ifndef HAVE_STRUCT_THREAD_TD_PCB
 320   add_cmd ("proc", class_obscure, bsd_kvm_proc_cmd,
 321            _("Set current context from proc address"), &bsd_kvm_cmdlist);
 322 #endif
 323   add_cmd ("pcb", class_obscure, bsd_kvm_pcb_cmd,
 324            /* i18n: PCB == "Process Control Block" */
 325            _("Set current context from pcb address"), &bsd_kvm_cmdlist);
 326 }