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 #include "gdbthread.h"
  29
  30 #include "gdb_assert.h"
  31 #include <fcntl.h>
  32 #include <kvm.h>
  33 #ifdef HAVE_NLIST_H
  34 #include <nlist.h>
  35 #endif
  36 #include <paths.h>
  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 device file.  */
  45 static const char *bsd_kvm_corefile;
  46
  47 /* Kernel memory interface descriptor.  */
  48 static kvm_t *core_kd;
  49
  50 /* Address of process control block.  */
  51 static struct pcb *bsd_kvm_paddr;
  52
  53 /* Pointer to architecture-specific function that reconstructs the
  54    register state from PCB and supplies it to REGCACHE.  */
  55 static int (*bsd_kvm_supply_pcb)(struct regcache *regcache, struct pcb *pcb);
  56
  57 /* Target ops for libkvm interface.  */
  58 static struct target_ops bsd_kvm_ops;
  59
  60 /* This is the ptid we use while we're connected to kvm.  The kvm
  61    target currently doesn't export any view of the running processes,
  62    so this represents the kernel task.  */
  63 static ptid_t bsd_kvm_ptid;
  64
  65 static void
  66 bsd_kvm_open (char *filename, int from_tty)
  67 {
  68   char errbuf[_POSIX2_LINE_MAX];
  69   char *execfile = NULL;
  70   kvm_t *temp_kd;
  71
  72   target_preopen (from_tty);
  73
  74   if (filename)
  75     {
  76       char *temp;
  77
  78       filename = tilde_expand (filename);
  79       if (filename[0] != '/')
  80         {
  81           temp = concat (current_directory, "/", filename, (char *)NULL);
  82           xfree (filename);
  83           filename = temp;
  84         }
  85     }
  86
  87   execfile = get_exec_file (0);
  88   temp_kd = kvm_openfiles (execfile, filename, NULL,
  89                            write_files ? O_RDWR : O_RDONLY, errbuf);
  90   if (temp_kd == NULL)
  91     error (("%s"), errbuf);
  92
  93   bsd_kvm_corefile = filename;
  94   unpush_target (&bsd_kvm_ops);
  95   core_kd = temp_kd;
  96   push_target (&bsd_kvm_ops);
  97
  98   add_thread_silent (bsd_kvm_ptid);
  99   inferior_ptid = bsd_kvm_ptid;
 100
 101   target_fetch_registers (get_current_regcache (), -1);
 102
 103   reinit_frame_cache ();
 104   print_stack_frame (get_selected_frame (NULL), -1, 1);
 105 }
 106
 107 static void
 108 bsd_kvm_close (int quitting)
 109 {
 110   if (core_kd)
 111     {
 112       if (kvm_close (core_kd) == -1)
 113         warning (("%s"), kvm_geterr(core_kd));
 114       core_kd = NULL;
 115     }
 116
 117   inferior_ptid = null_ptid;
 118   delete_thread_silent (bsd_kvm_ptid);
 119 }
 120
 121 static LONGEST
 122 bsd_kvm_xfer_memory (CORE_ADDR addr, ULONGEST len,
 123                      gdb_byte *readbuf, const gdb_byte *writebuf)
 124 {
 125   ssize_t nbytes = len;
 126
 127   if (readbuf)
 128     nbytes = kvm_read (core_kd, addr, readbuf, nbytes);
 129   if (writebuf && nbytes > 0)
 130     nbytes = kvm_write (core_kd, addr, writebuf, nbytes);
 131   return nbytes;
 132 }
 133
 134 static LONGEST
 135 bsd_kvm_xfer_partial (struct target_ops *ops, enum target_object object,
 136                       const char *annex, gdb_byte *readbuf,
 137                       const gdb_byte *writebuf,
 138                       ULONGEST offset, LONGEST len)
 139 {
 140   switch (object)
 141     {
 142     case TARGET_OBJECT_MEMORY:
 143       return bsd_kvm_xfer_memory (offset, len, readbuf, writebuf);
 144
 145     default:
 146       return -1;
 147     }
 148 }
 149
 150 static void
 151 bsd_kvm_files_info (struct target_ops *ops)
 152 {
 153   if (bsd_kvm_corefile && strcmp (bsd_kvm_corefile, _PATH_MEM) != 0)
 154     printf_filtered (_("\tUsing the kernel crash dump %s.\n"),
 155                      bsd_kvm_corefile);
 156   else
 157     printf_filtered (_("\tUsing the currently running kernel.\n"));
 158 }
 159
 160 /* Fetch process control block at address PADDR.  */
 161
 162 static int
 163 bsd_kvm_fetch_pcb (struct regcache *regcache, struct pcb *paddr)
 164 {
 165   struct pcb pcb;
 166
 167   if (kvm_read (core_kd, (unsigned long) paddr, &pcb, sizeof pcb) == -1)
 168     error (("%s"), kvm_geterr (core_kd));
 169
 170   gdb_assert (bsd_kvm_supply_pcb);
 171   return bsd_kvm_supply_pcb (regcache, &pcb);
 172 }
 173
 174 static void
 175 bsd_kvm_fetch_registers (struct regcache *regcache, int regnum)
 176 {
 177   struct nlist nl[2];
 178
 179   if (bsd_kvm_paddr)
 180     {
 181       bsd_kvm_fetch_pcb (regcache, bsd_kvm_paddr);
 182       return;
 183     }
 184
 185   /* On dumping core, BSD kernels store the faulting context (PCB)
 186      in the variable "dumppcb".  */
 187   memset (nl, 0, sizeof nl);
 188   nl[0].n_name = "_dumppcb";
 189
 190   if (kvm_nlist (core_kd, nl) == -1)
 191     error (("%s"), kvm_geterr (core_kd));
 192
 193   if (nl[0].n_value != 0)
 194     {
 195       /* Found dumppcb. If it contains a valid context, return
 196          immediately.  */
 197       if (bsd_kvm_fetch_pcb (regcache, (struct pcb *) nl[0].n_value))
 198         return;
 199     }
 200
 201   /* Traditional BSD kernels have a process proc0 that should always
 202      be present.  The address of proc0's PCB is stored in the variable
 203      "proc0paddr".  */
 204
 205   memset (nl, 0, sizeof nl);
 206   nl[0].n_name = "_proc0paddr";
 207
 208   if (kvm_nlist (core_kd, nl) == -1)
 209     error (("%s"), kvm_geterr (core_kd));
 210
 211   if (nl[0].n_value != 0)
 212     {
 213       struct pcb *paddr;
 214
 215       /* Found proc0paddr.  */
 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 (regcache, paddr);
 220       return;
 221     }
 222
 223 #ifdef HAVE_STRUCT_THREAD_TD_PCB
 224   /* In FreeBSD kernels for 5.0-RELEASE and later, the PCB no longer
 225      lives in `struct proc' but in `struct thread'.  The `struct
 226      thread' for the initial thread for proc0 can be found in the
 227      variable "thread0".  */
 228
 229   memset (nl, 0, sizeof nl);
 230   nl[0].n_name = "_thread0";
 231
 232   if (kvm_nlist (core_kd, nl) == -1)
 233     error (("%s"), kvm_geterr (core_kd));
 234
 235   if (nl[0].n_value != 0)
 236     {
 237       struct pcb *paddr;
 238
 239       /* Found thread0.  */
 240       nl[0].n_value += offsetof (struct thread, td_pcb);
 241       if (kvm_read (core_kd, nl[0].n_value, &paddr, sizeof paddr) == -1)
 242         error (("%s"), kvm_geterr (core_kd));
 243
 244       bsd_kvm_fetch_pcb (regcache, paddr);
 245       return;
 246     }
 247 #endif
 248
 249   /* i18n: PCB == "Process Control Block" */
 250   error (_("Cannot find a valid PCB"));
 251 }
 252 \f
 253
 254 /* Kernel memory interface commands.  */
 255 struct cmd_list_element *bsd_kvm_cmdlist;
 256
 257 static void
 258 bsd_kvm_cmd (char *arg, int fromtty)
 259 {
 260   /* ??? Should this become an alias for "target kvm"?  */
 261 }
 262
 263 #ifndef HAVE_STRUCT_THREAD_TD_PCB
 264
 265 static void
 266 bsd_kvm_proc_cmd (char *arg, int fromtty)
 267 {
 268   CORE_ADDR addr;
 269
 270   if (arg == NULL)
 271     error_no_arg (_("proc address"));
 272
 273   if (core_kd == NULL)
 274     error (_("No kernel memory image."));
 275
 276   addr = parse_and_eval_address (arg);
 277 #ifdef HAVE_STRUCT_LWP
 278   addr += offsetof (struct lwp, l_addr);
 279 #else
 280   addr += offsetof (struct proc, p_addr);
 281 #endif
 282
 283   if (kvm_read (core_kd, addr, &bsd_kvm_paddr, sizeof bsd_kvm_paddr) == -1)
 284     error (("%s"), kvm_geterr (core_kd));
 285
 286   target_fetch_registers (get_current_regcache (), -1);
 287
 288   reinit_frame_cache ();
 289   print_stack_frame (get_selected_frame (NULL), -1, 1);
 290 }
 291
 292 #endif
 293
 294 static void
 295 bsd_kvm_pcb_cmd (char *arg, int fromtty)
 296 {
 297   if (arg == NULL)
 298     /* i18n: PCB == "Process Control Block" */
 299     error_no_arg (_("pcb address"));
 300
 301   if (core_kd == NULL)
 302     error (_("No kernel memory image."));
 303
 304   bsd_kvm_paddr = (struct pcb *)(u_long) parse_and_eval_address (arg);
 305
 306   target_fetch_registers (get_current_regcache (), -1);
 307
 308   reinit_frame_cache ();
 309   print_stack_frame (get_selected_frame (NULL), -1, 1);
 310 }
 311
 312 static int
 313 bsd_kvm_thread_alive (ptid_t ptid)
 314 {
 315   return 1;
 316 }
 317
 318 static char *
 319 bsd_kvm_pid_to_str (ptid_t ptid)
 320 {
 321   static char buf[64];
 322   xsnprintf (buf, sizeof buf, "<kvm>");
 323   return buf;
 324 }
 325
 326 /* Add the libkvm interface to the list of all possible targets and
 327    register CUPPLY_PCB as the architecture-specific process control
 328    block interpreter.  */
 329
 330 void
 331 bsd_kvm_add_target (int (*supply_pcb)(struct regcache *, struct pcb *))
 332 {
 333   gdb_assert (bsd_kvm_supply_pcb == NULL);
 334   bsd_kvm_supply_pcb = supply_pcb;
 335
 336   bsd_kvm_ops.to_shortname = "kvm";
 337   bsd_kvm_ops.to_longname = _("Kernel memory interface");
 338   bsd_kvm_ops.to_doc = _("Use a kernel virtual memory image as a target.\n\
 339 Optionally specify the filename of a core dump.");
 340   bsd_kvm_ops.to_open = bsd_kvm_open;
 341   bsd_kvm_ops.to_close = bsd_kvm_close;
 342   bsd_kvm_ops.to_fetch_registers = bsd_kvm_fetch_registers;
 343   bsd_kvm_ops.to_xfer_partial = bsd_kvm_xfer_partial;
 344   bsd_kvm_ops.to_files_info = bsd_kvm_files_info;
 345   bsd_kvm_ops.to_thread_alive = bsd_kvm_thread_alive;
 346   bsd_kvm_ops.to_pid_to_str = bsd_kvm_pid_to_str;
 347   bsd_kvm_ops.to_stratum = process_stratum;
 348   bsd_kvm_ops.to_has_memory = 1;
 349   bsd_kvm_ops.to_has_stack = 1;
 350   bsd_kvm_ops.to_has_registers = 1;
 351   bsd_kvm_ops.to_magic = OPS_MAGIC;
 352
 353   add_target (&bsd_kvm_ops);
 354
 355   add_prefix_cmd ("kvm", class_obscure, bsd_kvm_cmd, _("\
 356 Generic command for manipulating the kernel memory interface."),
 357                   &bsd_kvm_cmdlist, "kvm ", 0, &cmdlist);
 358
 359 #ifndef HAVE_STRUCT_THREAD_TD_PCB
 360   add_cmd ("proc", class_obscure, bsd_kvm_proc_cmd,
 361            _("Set current context from proc address"), &bsd_kvm_cmdlist);
 362 #endif
 363   add_cmd ("pcb", class_obscure, bsd_kvm_pcb_cmd,
 364            /* i18n: PCB == "Process Control Block" */
 365            _("Set current context from pcb address"), &bsd_kvm_cmdlist);
 366
 367   /* Some notes on the ptid usage on this target.
 368
 369      The pid field represents the kvm inferior instance.  Currently,
 370      we don't support multiple kvm inferiors, but we start at 1
 371      anyway.  The lwp field is set to != 0, in case the core wants to
 372      refer to the whole kvm inferior with ptid(1,0,0).
 373
 374      If kvm is made to export running processes as gdb threads,
 375      the following form can be used:
 376      ptid (1, 1, 0) -> kvm inferior 1, in kernel
 377      ptid (1, 1, 1) -> kvm inferior 1, process 1
 378      ptid (1, 1, 2) -> kvm inferior 1, process 2
 379      ptid (1, 1, n) -> kvm inferior 1, process n
 380   */
 381   bsd_kvm_ptid = ptid_build (1, 1, 0);
 382 }