gdb/bsd-kvm.c

   1 /* BSD Kernel Data Access Library (libkvm) interface.
   2
   3    Copyright (C) 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., 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 (-1);
  95
  96   flush_cached_frames ();
  97   select_frame (get_current_frame ());
  98   print_stack_frame (get_selected_frame (NULL), -1, 1);
  99 }
 100
 101 static void
 102 bsd_kvm_close (int quitting)
 103 {
 104   if (core_kd)
 105     {
 106       if (kvm_close (core_kd) == -1)
 107         warning (("%s"), kvm_geterr(core_kd));
 108       core_kd = NULL;
 109     }
 110 }
 111
 112 static LONGEST
 113 bsd_kvm_xfer_memory (CORE_ADDR addr, ULONGEST len,
 114                      gdb_byte *readbuf, const gdb_byte *writebuf)
 115 {
 116   ssize_t nbytes = len;
 117
 118   if (readbuf)
 119     nbytes = kvm_read (core_kd, addr, readbuf, nbytes);
 120   if (writebuf && nbytes > 0)
 121     nbytes = kvm_write (core_kd, addr, writebuf, nbytes);
 122   return nbytes;
 123 }
 124
 125 static LONGEST
 126 bsd_kvm_xfer_partial (struct target_ops *ops, enum target_object object,
 127                       const char *annex, gdb_byte *readbuf,
 128                       const gdb_byte *writebuf,
 129                       ULONGEST offset, LONGEST len)
 130 {
 131   switch (object)
 132     {
 133     case TARGET_OBJECT_MEMORY:
 134       return bsd_kvm_xfer_memory (offset, len, readbuf, writebuf);
 135
 136     default:
 137       return -1;
 138     }
 139 }
 140
 141 static void
 142 bsd_kvm_files_info (struct target_ops *ops)
 143 {
 144   if (bsd_kvm_corefile && strcmp (bsd_kvm_corefile, _PATH_MEM) != 0)
 145     printf_filtered (_("\tUsing the kernel crash dump %s.\n"),
 146                      bsd_kvm_corefile);
 147   else
 148     printf_filtered (_("\tUsing the currently running kernel.\n"));
 149 }
 150
 151 /* Fetch process control block at address PADDR.  */
 152
 153 static int
 154 bsd_kvm_fetch_pcb (struct pcb *paddr)
 155 {
 156   struct pcb pcb;
 157
 158   if (kvm_read (core_kd, (unsigned long) paddr, &pcb, sizeof pcb) == -1)
 159     error (("%s"), kvm_geterr (core_kd));
 160
 161   gdb_assert (bsd_kvm_supply_pcb);
 162   return bsd_kvm_supply_pcb (current_regcache, &pcb);
 163 }
 164
 165 static void
 166 bsd_kvm_fetch_registers (int regnum)
 167 {
 168   struct nlist nl[2];
 169
 170   if (bsd_kvm_paddr)
 171     {
 172       bsd_kvm_fetch_pcb (bsd_kvm_paddr);
 173       return;
 174     }
 175
 176   /* On dumping core, BSD kernels store the faulting context (PCB)
 177      in the variable "dumppcb".  */
 178   memset (nl, 0, sizeof nl);
 179   nl[0].n_name = "_dumppcb";
 180
 181   if (kvm_nlist (core_kd, nl) == -1)
 182     error (("%s"), kvm_geterr (core_kd));
 183
 184   if (nl[0].n_value != 0)
 185     {
 186       /* Found dumppcb. If it contains a valid context, return
 187          immediately.  */
 188       if (bsd_kvm_fetch_pcb ((struct pcb *) nl[0].n_value))
 189         return;
 190     }
 191
 192   /* Traditional BSD kernels have a process proc0 that should always
 193      be present.  The address of proc0's PCB is stored in the variable
 194      "proc0paddr".  */
 195
 196   memset (nl, 0, sizeof nl);
 197   nl[0].n_name = "_proc0paddr";
 198
 199   if (kvm_nlist (core_kd, nl) == -1)
 200     error (("%s"), kvm_geterr (core_kd));
 201
 202   if (nl[0].n_value != 0)
 203     {
 204       struct pcb *paddr;
 205
 206       /* Found proc0paddr.  */
 207       if (kvm_read (core_kd, nl[0].n_value, &paddr, sizeof paddr) == -1)
 208         error (("%s"), kvm_geterr (core_kd));
 209
 210       bsd_kvm_fetch_pcb (paddr);
 211       return;
 212     }
 213
 214 #ifdef HAVE_STRUCT_THREAD_TD_PCB
 215   /* In FreeBSD kernels for 5.0-RELEASE and later, the PCB no longer
 216      lives in `struct proc' but in `struct thread'.  The `struct
 217      thread' for the initial thread for proc0 can be found in the
 218      variable "thread0".  */
 219
 220   memset (nl, 0, sizeof nl);
 221   nl[0].n_name = "_thread0";
 222
 223   if (kvm_nlist (core_kd, nl) == -1)
 224     error (("%s"), kvm_geterr (core_kd));
 225
 226   if (nl[0].n_value != 0)
 227     {
 228       struct pcb *paddr;
 229
 230       /* Found thread0.  */
 231       nl[0].n_value += offsetof (struct thread, td_pcb);
 232       if (kvm_read (core_kd, nl[0].n_value, &paddr, sizeof paddr) == -1)
 233         error (("%s"), kvm_geterr (core_kd));
 234
 235       bsd_kvm_fetch_pcb (paddr);
 236       return;
 237     }
 238 #endif
 239
 240   /* i18n: PCB == "Process Control Block" */
 241   error (_("Cannot find a valid PCB"));
 242 }
 243 \f
 244
 245 /* Kernel memory interface commands.  */
 246 struct cmd_list_element *bsd_kvm_cmdlist;
 247
 248 static void
 249 bsd_kvm_cmd (char *arg, int fromtty)
 250 {
 251   /* ??? Should this become an alias for "target kvm"?  */
 252 }
 253
 254 #ifndef HAVE_STRUCT_THREAD_TD_PCB
 255
 256 static void
 257 bsd_kvm_proc_cmd (char *arg, int fromtty)
 258 {
 259   CORE_ADDR addr;
 260
 261   if (arg == NULL)
 262     error_no_arg (_("proc address"));
 263
 264   if (core_kd == NULL)
 265     error (_("No kernel memory image."));
 266
 267   addr = parse_and_eval_address (arg);
 268 #ifdef HAVE_STRUCT_LWP
 269   addr += offsetof (struct lwp, l_addr);
 270 #else
 271   addr += offsetof (struct proc, p_addr);
 272 #endif
 273
 274   if (kvm_read (core_kd, addr, &bsd_kvm_paddr, sizeof bsd_kvm_paddr) == -1)
 275     error (("%s"), kvm_geterr (core_kd));
 276
 277   target_fetch_registers (-1);
 278
 279   flush_cached_frames ();
 280   select_frame (get_current_frame ());
 281   print_stack_frame (get_selected_frame (NULL), -1, 1);
 282 }
 283
 284 #endif
 285
 286 static void
 287 bsd_kvm_pcb_cmd (char *arg, int fromtty)
 288 {
 289   if (arg == NULL)
 290     /* i18n: PCB == "Process Control Block" */
 291     error_no_arg (_("pcb address"));
 292
 293   if (core_kd == NULL)
 294     error (_("No kernel memory image."));
 295
 296   bsd_kvm_paddr = (struct pcb *)(u_long) parse_and_eval_address (arg);
 297
 298   target_fetch_registers (-1);
 299
 300   flush_cached_frames ();
 301   select_frame (get_current_frame ());
 302   print_stack_frame (get_selected_frame (NULL), -1, 1);
 303 }
 304
 305 /* Add the libkvm interface to the list of all possible targets and
 306    register CUPPLY_PCB as the architecture-specific process control
 307    block interpreter.  */
 308
 309 void
 310 bsd_kvm_add_target (int (*supply_pcb)(struct regcache *, struct pcb *))
 311 {
 312   gdb_assert (bsd_kvm_supply_pcb == NULL);
 313   bsd_kvm_supply_pcb = supply_pcb;
 314
 315   bsd_kvm_ops.to_shortname = "kvm";
 316   bsd_kvm_ops.to_longname = _("Kernel memory interface");
 317   bsd_kvm_ops.to_doc = _("Use a kernel virtual memory image as a target.\n\
 318 Optionally specify the filename of a core dump.");
 319   bsd_kvm_ops.to_open = bsd_kvm_open;
 320   bsd_kvm_ops.to_close = bsd_kvm_close;
 321   bsd_kvm_ops.to_fetch_registers = bsd_kvm_fetch_registers;
 322   bsd_kvm_ops.to_xfer_partial = bsd_kvm_xfer_partial;
 323   bsd_kvm_ops.to_files_info = bsd_kvm_files_info;
 324   bsd_kvm_ops.to_stratum = process_stratum;
 325   bsd_kvm_ops.to_has_memory = 1;
 326   bsd_kvm_ops.to_has_stack = 1;
 327   bsd_kvm_ops.to_has_registers = 1;
 328   bsd_kvm_ops.to_magic = OPS_MAGIC;
 329
 330   add_target (&bsd_kvm_ops);
 331
 332   add_prefix_cmd ("kvm", class_obscure, bsd_kvm_cmd, _("\
 333 Generic command for manipulating the kernel memory interface."),
 334                   &bsd_kvm_cmdlist, "kvm ", 0, &cmdlist);
 335
 336 #ifndef HAVE_STRUCT_THREAD_TD_PCB
 337   add_cmd ("proc", class_obscure, bsd_kvm_proc_cmd,
 338            _("Set current context from proc address"), &bsd_kvm_cmdlist);
 339 #endif
 340   add_cmd ("pcb", class_obscure, bsd_kvm_pcb_cmd,
 341            /* i18n: PCB == "Process Control Block" */
 342            _("Set current context from pcb address"), &bsd_kvm_cmdlist);
 343 }