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 "frame.h"
  24 #include "regcache.h"
  25 #include "target.h"
  26
  27 #include "gdb_assert.h"
  28 #include <fcntl.h>
  29 #include <kvm.h>
  30 #include <nlist.h>
  31 #include "readline/readline.h"
  32 #include <sys/param.h>
  33 #include <sys/user.h>
  34
  35 #include "bsd-kvm.h"
  36
  37 /* Kernel memory interface descriptor.  */
  38 kvm_t *core_kd;
  39
  40 /* Address of process control block.  */
  41 struct pcb *bsd_kvm_paddr;
  42
  43 /* Pointer to architecture-specific function that reconstructs the
  44    register state from PCB and supplies it to REGCACHE.  */
  45 int (*bsd_kvm_supply_pcb)(struct regcache *regcache, struct pcb *pcb);
  46
  47 /* Target ops for libkvm interface.  */
  48 struct target_ops bsd_kvm_ops;
  49
  50 static void
  51 bsd_kvm_open (char *filename, int from_tty)
  52 {
  53   char errbuf[_POSIX2_LINE_MAX];
  54   char *execfile = NULL;
  55   kvm_t *temp_kd;
  56
  57   target_preopen (from_tty);
  58
  59   if (filename)
  60     {
  61       char *temp;
  62
  63       filename = tilde_expand (filename);
  64       if (filename[0] != '/')
  65         {
  66           temp = concat (current_directory, "/", filename, NULL);
  67           xfree (filename);
  68           filename = temp;
  69         }
  70     }
  71
  72   temp_kd = kvm_openfiles (execfile, filename, NULL, O_RDONLY, errbuf);
  73   if (temp_kd == NULL)
  74     error ("%s", errbuf);
  75
  76   unpush_target (&bsd_kvm_ops);
  77   core_kd = temp_kd;
  78   push_target (&bsd_kvm_ops);
  79
  80   target_fetch_registers (-1);
  81
  82   flush_cached_frames ();
  83   select_frame (get_current_frame ());
  84   print_stack_frame (get_selected_frame (), -1, 1);
  85 }
  86
  87 static void
  88 bsd_kvm_close (int quitting)
  89 {
  90   if (core_kd)
  91     {
  92       if (kvm_close (core_kd) == -1)
  93         warning ("%s", kvm_geterr(core_kd));
  94       core_kd = NULL;
  95     }
  96 }
  97
  98 static int
  99 bsd_kvm_xfer_memory (CORE_ADDR memaddr, char *myaddr, int len,
 100                     int write, struct mem_attrib *attrib,
 101                     struct target_ops *ops)
 102 {
 103   if (write)
 104     return kvm_write (core_kd, memaddr, myaddr, len);
 105   else
 106     return kvm_read (core_kd, memaddr, myaddr, len);
 107
 108   return -1;
 109 }
 110
 111 /* Fetch process control block at address PADDR.  */
 112
 113 static int
 114 bsd_kvm_fetch_pcb (struct pcb *paddr)
 115 {
 116   struct pcb pcb;
 117
 118   if (kvm_read (core_kd, (unsigned long) paddr, &pcb, sizeof pcb) == -1)
 119     error ("%s", kvm_geterr (core_kd));
 120
 121   gdb_assert (bsd_kvm_supply_pcb);
 122   return bsd_kvm_supply_pcb (current_regcache, &pcb);
 123 }
 124
 125 static void
 126 bsd_kvm_fetch_registers (int regnum)
 127 {
 128   struct nlist nl[2];
 129
 130   if (bsd_kvm_paddr)
 131     {
 132       bsd_kvm_fetch_pcb (bsd_kvm_paddr);
 133       return;
 134     }
 135
 136   /* On dumping core, BSD kernels store the faulting context (PCB)
 137      in the variable "dumppcb".  */
 138   memset (nl, 0, sizeof nl);
 139   nl[0].n_name = "_dumppcb";
 140
 141   if (kvm_nlist (core_kd, nl) == -1)
 142     error ("%s", kvm_geterr (core_kd));
 143
 144   if (nl[0].n_value != 0)
 145     {
 146       /* Found dumppcb. If it contains a valid context, return
 147          immediately.  */
 148       if (bsd_kvm_fetch_pcb ((struct pcb *) nl[0].n_value))
 149         return;
 150     }
 151
 152   /* Traditional BSD kernels have a process proc0 that should always
 153      be present.  The address of proc0's PCB is stored in the variable
 154      "proc0paddr".  */
 155
 156   memset (nl, 0, sizeof nl);
 157   nl[0].n_name = "_proc0paddr";
 158
 159   if (kvm_nlist (core_kd, nl) == -1)
 160     error ("%s", kvm_geterr (core_kd));
 161
 162   if (nl[0].n_value != 0)
 163     {
 164       struct pcb *paddr;
 165
 166       /* Found proc0paddr.  */
 167       if (kvm_read (core_kd, nl[0].n_value, &paddr, sizeof paddr) == -1)
 168         error ("%s", kvm_geterr (core_kd));
 169
 170       bsd_kvm_fetch_pcb (paddr);
 171       return;
 172     }
 173
 174 #ifdef HAVE_STRUCT_THREAD_TD_PCB
 175   /* In FreeBSD kernels for 5.0-RELEASE and later, the PCB no longer
 176      lives in `struct proc' but in `struct thread'.  The `struct
 177      thread' for the initial thread for proc0 can be found in the
 178      variable "thread0".  */
 179
 180   memset (nl, 0, sizeof nl);
 181   nl[0].n_name = "_thread0";
 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 thread0.  */
 191       nl[0].n_value += offsetof (struct thread, td_pcb);
 192       if (kvm_read (core_kd, nl[0].n_value, &paddr, sizeof paddr) == -1)
 193         error ("%s", kvm_geterr (core_kd));
 194
 195       bsd_kvm_fetch_pcb (paddr);
 196       return;
 197     }
 198 #endif
 199
 200   error ("Cannot find a valid PCB");
 201 }
 202 \f
 203
 204 /* Add the libkvm interface to the list of all possible targets and
 205    register CUPPLY_PCB as the architecture-specific process control
 206    block interpreter.  */
 207
 208 void
 209 bsd_kvm_add_target (int (*supply_pcb)(struct regcache *, struct pcb *))
 210 {
 211   gdb_assert (bsd_kvm_supply_pcb == NULL);
 212   bsd_kvm_supply_pcb = supply_pcb;
 213
 214   bsd_kvm_ops.to_shortname = "kvm";
 215   bsd_kvm_ops.to_longname = "Kernel memory interface";
 216   bsd_kvm_ops.to_doc = "Use a kernel virtual memory image as a target.\n\
 217 Optionally specify the filename of a core dump.";
 218   bsd_kvm_ops.to_open = bsd_kvm_open;
 219   bsd_kvm_ops.to_close = bsd_kvm_close;
 220   bsd_kvm_ops.to_fetch_registers = bsd_kvm_fetch_registers;
 221   bsd_kvm_ops.to_xfer_memory = bsd_kvm_xfer_memory;
 222   bsd_kvm_ops.to_stratum = process_stratum;
 223   bsd_kvm_ops.to_has_memory = 1;
 224   bsd_kvm_ops.to_has_stack = 1;
 225   bsd_kvm_ops.to_has_registers = 1;
 226   bsd_kvm_ops.to_magic = OPS_MAGIC;
 227
 228   add_target (&bsd_kvm_ops);
 229 }