gdb/bsd-kvm.c

   1 /* BSD Kernel Data Access Library (libkvm) interface.
   2
   3    Copyright 2004 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 int
 107 bsd_kvm_xfer_memory (CORE_ADDR memaddr, char *myaddr, int len,
 108                     int write, struct mem_attrib *attrib,
 109                     struct target_ops *ops)
 110 {
 111   if (write)
 112     return kvm_write (core_kd, memaddr, myaddr, len);
 113   else
 114     return kvm_read (core_kd, memaddr, myaddr, len);
 115
 116   return -1;
 117 }
 118
 119 /* Fetch process control block at address PADDR.  */
 120
 121 static int
 122 bsd_kvm_fetch_pcb (struct pcb *paddr)
 123 {
 124   struct pcb pcb;
 125
 126   if (kvm_read (core_kd, (unsigned long) paddr, &pcb, sizeof pcb) == -1)
 127     error (("%s"), kvm_geterr (core_kd));
 128
 129   gdb_assert (bsd_kvm_supply_pcb);
 130   return bsd_kvm_supply_pcb (current_regcache, &pcb);
 131 }
 132
 133 static void
 134 bsd_kvm_fetch_registers (int regnum)
 135 {
 136   struct nlist nl[2];
 137
 138   if (bsd_kvm_paddr)
 139     {
 140       bsd_kvm_fetch_pcb (bsd_kvm_paddr);
 141       return;
 142     }
 143
 144   /* On dumping core, BSD kernels store the faulting context (PCB)
 145      in the variable "dumppcb".  */
 146   memset (nl, 0, sizeof nl);
 147   nl[0].n_name = "_dumppcb";
 148
 149   if (kvm_nlist (core_kd, nl) == -1)
 150     error (("%s"), kvm_geterr (core_kd));
 151
 152   if (nl[0].n_value != 0)
 153     {
 154       /* Found dumppcb. If it contains a valid context, return
 155          immediately.  */
 156       if (bsd_kvm_fetch_pcb ((struct pcb *) nl[0].n_value))
 157         return;
 158     }
 159
 160   /* Traditional BSD kernels have a process proc0 that should always
 161      be present.  The address of proc0's PCB is stored in the variable
 162      "proc0paddr".  */
 163
 164   memset (nl, 0, sizeof nl);
 165   nl[0].n_name = "_proc0paddr";
 166
 167   if (kvm_nlist (core_kd, nl) == -1)
 168     error (("%s"), kvm_geterr (core_kd));
 169
 170   if (nl[0].n_value != 0)
 171     {
 172       struct pcb *paddr;
 173
 174       /* Found proc0paddr.  */
 175       if (kvm_read (core_kd, nl[0].n_value, &paddr, sizeof paddr) == -1)
 176         error (("%s"), kvm_geterr (core_kd));
 177
 178       bsd_kvm_fetch_pcb (paddr);
 179       return;
 180     }
 181
 182 #ifdef HAVE_STRUCT_THREAD_TD_PCB
 183   /* In FreeBSD kernels for 5.0-RELEASE and later, the PCB no longer
 184      lives in `struct proc' but in `struct thread'.  The `struct
 185      thread' for the initial thread for proc0 can be found in the
 186      variable "thread0".  */
 187
 188   memset (nl, 0, sizeof nl);
 189   nl[0].n_name = "_thread0";
 190
 191   if (kvm_nlist (core_kd, nl) == -1)
 192     error (("%s"), kvm_geterr (core_kd));
 193
 194   if (nl[0].n_value != 0)
 195     {
 196       struct pcb *paddr;
 197
 198       /* Found thread0.  */
 199       nl[0].n_value += offsetof (struct thread, td_pcb);
 200       if (kvm_read (core_kd, nl[0].n_value, &paddr, sizeof paddr) == -1)
 201         error (("%s"), kvm_geterr (core_kd));
 202
 203       bsd_kvm_fetch_pcb (paddr);
 204       return;
 205     }
 206 #endif
 207
 208   /* i18n: PCB == "Process Control Block" */
 209   error (_("Cannot find a valid PCB"));
 210 }
 211 \f
 212
 213 /* Kernel memory interface commands.  */
 214 struct cmd_list_element *bsd_kvm_cmdlist;
 215
 216 static void
 217 bsd_kvm_cmd (char *arg, int fromtty)
 218 {
 219   /* ??? Should this become an alias for "target kvm"?  */
 220 }
 221
 222 #ifndef HAVE_STRUCT_THREAD_TD_PCB
 223
 224 static void
 225 bsd_kvm_proc_cmd (char *arg, int fromtty)
 226 {
 227   CORE_ADDR addr;
 228
 229   if (arg == NULL)
 230     error_no_arg (_("proc address"));
 231
 232   if (core_kd == NULL)
 233     error (_("No kernel memory image."));
 234
 235   addr = parse_and_eval_address (arg);
 236 #ifdef HAVE_STRUCT_LWP
 237   addr += offsetof (struct lwp, l_addr);
 238 #else
 239   addr += offsetof (struct proc, p_addr);
 240 #endif
 241
 242   if (kvm_read (core_kd, addr, &bsd_kvm_paddr, sizeof bsd_kvm_paddr) == -1)
 243     error (("%s"), kvm_geterr (core_kd));
 244
 245   target_fetch_registers (-1);
 246
 247   flush_cached_frames ();
 248   select_frame (get_current_frame ());
 249   print_stack_frame (get_selected_frame (NULL), -1, 1);
 250 }
 251
 252 #endif
 253
 254 static void
 255 bsd_kvm_pcb_cmd (char *arg, int fromtty)
 256 {
 257   if (arg == NULL)
 258     /* i18n: PCB == "Process Control Block" */
 259     error_no_arg (_("pcb address"));
 260
 261   if (core_kd == NULL)
 262     error (_("No kernel memory image."));
 263
 264   bsd_kvm_paddr = (struct pcb *)(u_long) parse_and_eval_address (arg);
 265
 266   target_fetch_registers (-1);
 267
 268   flush_cached_frames ();
 269   select_frame (get_current_frame ());
 270   print_stack_frame (get_selected_frame (NULL), -1, 1);
 271 }
 272
 273 /* Add the libkvm interface to the list of all possible targets and
 274    register CUPPLY_PCB as the architecture-specific process control
 275    block interpreter.  */
 276
 277 void
 278 bsd_kvm_add_target (int (*supply_pcb)(struct regcache *, struct pcb *))
 279 {
 280   gdb_assert (bsd_kvm_supply_pcb == NULL);
 281   bsd_kvm_supply_pcb = supply_pcb;
 282
 283   bsd_kvm_ops.to_shortname = "kvm";
 284   bsd_kvm_ops.to_longname = _("Kernel memory interface");
 285   bsd_kvm_ops.to_doc = _("Use a kernel virtual memory image as a target.\n\
 286 Optionally specify the filename of a core dump.");
 287   bsd_kvm_ops.to_open = bsd_kvm_open;
 288   bsd_kvm_ops.to_close = bsd_kvm_close;
 289   bsd_kvm_ops.to_fetch_registers = bsd_kvm_fetch_registers;
 290   bsd_kvm_ops.deprecated_xfer_memory = bsd_kvm_xfer_memory;
 291   bsd_kvm_ops.to_stratum = process_stratum;
 292   bsd_kvm_ops.to_has_memory = 1;
 293   bsd_kvm_ops.to_has_stack = 1;
 294   bsd_kvm_ops.to_has_registers = 1;
 295   bsd_kvm_ops.to_magic = OPS_MAGIC;
 296
 297   add_target (&bsd_kvm_ops);
 298
 299   add_prefix_cmd ("kvm", class_obscure, bsd_kvm_cmd, _("\
 300 Generic command for manipulating the kernel memory interface."),
 301                   &bsd_kvm_cmdlist, "kvm ", 0, &cmdlist);
 302
 303 #ifndef HAVE_STRUCT_THREAD_TD_PCB
 304   add_cmd ("proc", class_obscure, bsd_kvm_proc_cmd,
 305            _("Set current context from proc address"), &bsd_kvm_cmdlist);
 306 #endif
 307   add_cmd ("pcb", class_obscure, bsd_kvm_pcb_cmd,
 308            /* i18n: PCB == "Process Control Block" */
 309            _("Set current context from pcb address"), &bsd_kvm_cmdlist);
 310 }