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
bsd_kvm_open(char * filename,int from_tty)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 (), -1, 1);
93 }
94
95 static void
bsd_kvm_close(int quitting)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
bsd_kvm_xfer_memory(CORE_ADDR memaddr,char * myaddr,int len,int write,struct mem_attrib * attrib,struct target_ops * ops)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
bsd_kvm_fetch_pcb(struct pcb * paddr)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
bsd_kvm_fetch_registers(int regnum)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 error ("Cannot find a valid PCB");
209 }
210
211
212 /* Kernel memory interface commands. */
213 struct cmd_list_element *bsd_kvm_cmdlist;
214
215 static void
bsd_kvm_cmd(char * arg,int fromtty)216 bsd_kvm_cmd (char *arg, int fromtty)
217 {
218 /* ??? Should this become an alias for "target kvm"? */
219 }
220
221 #ifndef HAVE_STRUCT_THREAD_TD_PCB
222
223 static void
bsd_kvm_proc_cmd(char * arg,int fromtty)224 bsd_kvm_proc_cmd (char *arg, int fromtty)
225 {
226 CORE_ADDR addr;
227
228 if (arg == NULL)
229 error_no_arg ("proc address");
230
231 if (core_kd == NULL)
232 error ("No kernel memory image.");
233
234 addr = parse_and_eval_address (arg);
235 #ifdef HAVE_STRUCT_LWP
236 addr += offsetof (struct lwp, l_addr);
237 #else
238 addr += offsetof (struct proc, p_addr);
239 #endif
240
241 if (kvm_read (core_kd, addr, &bsd_kvm_paddr, sizeof bsd_kvm_paddr) == -1)
242 error ("%s", kvm_geterr (core_kd));
243
244 target_fetch_registers (-1);
245
246 flush_cached_frames ();
247 select_frame (get_current_frame ());
248 print_stack_frame (get_selected_frame (), -1, 1);
249 }
250
251 #endif
252
253 static void
bsd_kvm_pcb_cmd(char * arg,int fromtty)254 bsd_kvm_pcb_cmd (char *arg, int fromtty)
255 {
256 if (arg == NULL)
257 error_no_arg ("pcb address");
258
259 if (core_kd == NULL)
260 error ("No kernel memory image.");
261
262 bsd_kvm_paddr = (struct pcb *) parse_and_eval_address (arg);
263
264 target_fetch_registers (-1);
265
266 flush_cached_frames ();
267 select_frame (get_current_frame ());
268 print_stack_frame (get_selected_frame (), -1, 1);
269 }
270
271 /* Add the libkvm interface to the list of all possible targets and
272 register CUPPLY_PCB as the architecture-specific process control
273 block interpreter. */
274
275 void
bsd_kvm_add_target(int (* supply_pcb)(struct regcache *,struct pcb *))276 bsd_kvm_add_target (int (*supply_pcb)(struct regcache *, struct pcb *))
277 {
278 gdb_assert (bsd_kvm_supply_pcb == NULL);
279 bsd_kvm_supply_pcb = supply_pcb;
280
281 bsd_kvm_ops.to_shortname = "kvm";
282 bsd_kvm_ops.to_longname = "Kernel memory interface";
283 bsd_kvm_ops.to_doc = "Use a kernel virtual memory image as a target.\n\
284 Optionally specify the filename of a core dump.";
285 bsd_kvm_ops.to_open = bsd_kvm_open;
286 bsd_kvm_ops.to_close = bsd_kvm_close;
287 bsd_kvm_ops.to_fetch_registers = bsd_kvm_fetch_registers;
288 bsd_kvm_ops.deprecated_xfer_memory = bsd_kvm_xfer_memory;
289 bsd_kvm_ops.to_stratum = process_stratum;
290 bsd_kvm_ops.to_has_memory = 1;
291 bsd_kvm_ops.to_has_stack = 1;
292 bsd_kvm_ops.to_has_registers = 1;
293 bsd_kvm_ops.to_magic = OPS_MAGIC;
294
295 add_target (&bsd_kvm_ops);
296
297 add_prefix_cmd ("kvm", class_obscure, bsd_kvm_cmd, "\
298 Generic command for manipulating the kernel memory interface.",
299 &bsd_kvm_cmdlist, "kvm ", 0, &cmdlist);
300
301 #ifndef HAVE_STRUCT_THREAD_TD_PCB
302 add_cmd ("proc", class_obscure, bsd_kvm_proc_cmd,
303 "Set current context from proc address", &bsd_kvm_cmdlist);
304 #endif
305 add_cmd ("pcb", class_obscure, bsd_kvm_pcb_cmd,
306 "Set current context from pcb address", &bsd_kvm_cmdlist);
307 }
308