| 1 | /* BSD Kernel Data Access Library (libkvm) interface. |
| 2 | |
| 3 | Copyright (C) 2004-2019 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 | #define _KMEMUSER |
| 21 | #include "defs.h" |
| 22 | #include "cli/cli-cmds.h" |
| 23 | #include "command.h" |
| 24 | #include "frame.h" |
| 25 | #include "regcache.h" |
| 26 | #include "target.h" |
| 27 | #include "process-stratum-target.h" |
| 28 | #include "value.h" |
| 29 | #include "gdbcore.h" |
| 30 | #include "inferior.h" /* for get_exec_file */ |
| 31 | #include "gdbthread.h" |
| 32 | |
| 33 | #include <fcntl.h> |
| 34 | #include <kvm.h> |
| 35 | #ifdef HAVE_NLIST_H |
| 36 | #include <nlist.h> |
| 37 | #endif |
| 38 | #include <paths.h> |
| 39 | #include "readline/readline.h" |
| 40 | #include <sys/param.h> |
| 41 | #include <sys/proc.h> |
| 42 | #ifdef HAVE_SYS_USER_H |
| 43 | #include <sys/user.h> |
| 44 | #endif |
| 45 | |
| 46 | #include "bsd-kvm.h" |
| 47 | |
| 48 | /* Kernel memory device file. */ |
| 49 | static const char *bsd_kvm_corefile; |
| 50 | |
| 51 | /* Kernel memory interface descriptor. */ |
| 52 | static kvm_t *core_kd; |
| 53 | |
| 54 | /* Address of process control block. */ |
| 55 | static struct pcb *bsd_kvm_paddr; |
| 56 | |
| 57 | /* Pointer to architecture-specific function that reconstructs the |
| 58 | register state from PCB and supplies it to REGCACHE. */ |
| 59 | static int (*bsd_kvm_supply_pcb)(struct regcache *regcache, struct pcb *pcb); |
| 60 | |
| 61 | /* This is the ptid we use while we're connected to kvm. The kvm |
| 62 | target currently doesn't export any view of the running processes, |
| 63 | so this represents the kernel task. */ |
| 64 | static ptid_t bsd_kvm_ptid; |
| 65 | |
| 66 | /* The libkvm target. */ |
| 67 | |
| 68 | static const target_info bsd_kvm_target_info = { |
| 69 | "kvm", |
| 70 | N_("Kernel memory interface"), |
| 71 | N_("Use a kernel virtual memory image as a target.\n\ |
| 72 | Optionally specify the filename of a core dump.") |
| 73 | }; |
| 74 | |
| 75 | class bsd_kvm_target final : public process_stratum_target |
| 76 | { |
| 77 | public: |
| 78 | bsd_kvm_target () = default; |
| 79 | |
| 80 | const target_info &info () const override |
| 81 | { return bsd_kvm_target_info; } |
| 82 | |
| 83 | void close () override; |
| 84 | |
| 85 | void fetch_registers (struct regcache *, int) override; |
| 86 | enum target_xfer_status xfer_partial (enum target_object object, |
| 87 | const char *annex, |
| 88 | gdb_byte *readbuf, |
| 89 | const gdb_byte *writebuf, |
| 90 | ULONGEST offset, ULONGEST len, |
| 91 | ULONGEST *xfered_len) override; |
| 92 | |
| 93 | void files_info () override; |
| 94 | bool thread_alive (ptid_t ptid) override; |
| 95 | const char *pid_to_str (ptid_t) override; |
| 96 | |
| 97 | bool has_memory () override { return true; } |
| 98 | bool has_stack () override { return true; } |
| 99 | bool has_registers () override { return true; } |
| 100 | }; |
| 101 | |
| 102 | /* Target ops for libkvm interface. */ |
| 103 | static bsd_kvm_target bsd_kvm_ops; |
| 104 | |
| 105 | static void |
| 106 | bsd_kvm_target_open (const char *arg, int from_tty) |
| 107 | { |
| 108 | char errbuf[_POSIX2_LINE_MAX]; |
| 109 | char *execfile = NULL; |
| 110 | kvm_t *temp_kd; |
| 111 | char *filename = NULL; |
| 112 | |
| 113 | target_preopen (from_tty); |
| 114 | |
| 115 | if (arg) |
| 116 | { |
| 117 | char *temp; |
| 118 | |
| 119 | filename = tilde_expand (arg); |
| 120 | if (filename[0] != '/') |
| 121 | { |
| 122 | temp = concat (current_directory, "/", filename, (char *)NULL); |
| 123 | xfree (filename); |
| 124 | filename = temp; |
| 125 | } |
| 126 | } |
| 127 | |
| 128 | execfile = get_exec_file (0); |
| 129 | temp_kd = kvm_openfiles (execfile, filename, NULL, |
| 130 | write_files ? O_RDWR : O_RDONLY, errbuf); |
| 131 | if (temp_kd == NULL) |
| 132 | error (("%s"), errbuf); |
| 133 | |
| 134 | bsd_kvm_corefile = filename; |
| 135 | unpush_target (&bsd_kvm_ops); |
| 136 | core_kd = temp_kd; |
| 137 | push_target (&bsd_kvm_ops); |
| 138 | |
| 139 | add_thread_silent (bsd_kvm_ptid); |
| 140 | inferior_ptid = bsd_kvm_ptid; |
| 141 | |
| 142 | target_fetch_registers (get_current_regcache (), -1); |
| 143 | |
| 144 | reinit_frame_cache (); |
| 145 | print_stack_frame (get_selected_frame (NULL), 0, SRC_AND_LOC, 1); |
| 146 | } |
| 147 | |
| 148 | void |
| 149 | bsd_kvm_target::close () |
| 150 | { |
| 151 | if (core_kd) |
| 152 | { |
| 153 | if (kvm_close (core_kd) == -1) |
| 154 | warning (("%s"), kvm_geterr(core_kd)); |
| 155 | core_kd = NULL; |
| 156 | } |
| 157 | |
| 158 | inferior_ptid = null_ptid; |
| 159 | discard_all_inferiors (); |
| 160 | } |
| 161 | |
| 162 | static LONGEST |
| 163 | bsd_kvm_xfer_memory (CORE_ADDR addr, ULONGEST len, |
| 164 | gdb_byte *readbuf, const gdb_byte *writebuf) |
| 165 | { |
| 166 | ssize_t nbytes = len; |
| 167 | |
| 168 | if (readbuf) |
| 169 | nbytes = kvm_read (core_kd, addr, readbuf, nbytes); |
| 170 | if (writebuf && nbytes > 0) |
| 171 | nbytes = kvm_write (core_kd, addr, writebuf, nbytes); |
| 172 | return nbytes; |
| 173 | } |
| 174 | |
| 175 | enum target_xfer_status |
| 176 | bsd_kvm_target::xfer_partial (enum target_object object, |
| 177 | const char *annex, gdb_byte *readbuf, |
| 178 | const gdb_byte *writebuf, |
| 179 | ULONGEST offset, ULONGEST len, ULONGEST *xfered_len) |
| 180 | { |
| 181 | switch (object) |
| 182 | { |
| 183 | case TARGET_OBJECT_MEMORY: |
| 184 | { |
| 185 | LONGEST ret = bsd_kvm_xfer_memory (offset, len, readbuf, writebuf); |
| 186 | |
| 187 | if (ret < 0) |
| 188 | return TARGET_XFER_E_IO; |
| 189 | else if (ret == 0) |
| 190 | return TARGET_XFER_EOF; |
| 191 | else |
| 192 | { |
| 193 | *xfered_len = (ULONGEST) ret; |
| 194 | return TARGET_XFER_OK; |
| 195 | } |
| 196 | } |
| 197 | |
| 198 | default: |
| 199 | return TARGET_XFER_E_IO; |
| 200 | } |
| 201 | } |
| 202 | |
| 203 | void |
| 204 | bsd_kvm_target::files_info () |
| 205 | { |
| 206 | if (bsd_kvm_corefile && strcmp (bsd_kvm_corefile, _PATH_MEM) != 0) |
| 207 | printf_filtered (_("\tUsing the kernel crash dump %s.\n"), |
| 208 | bsd_kvm_corefile); |
| 209 | else |
| 210 | printf_filtered (_("\tUsing the currently running kernel.\n")); |
| 211 | } |
| 212 | |
| 213 | /* Fetch process control block at address PADDR. */ |
| 214 | |
| 215 | static int |
| 216 | bsd_kvm_fetch_pcb (struct regcache *regcache, struct pcb *paddr) |
| 217 | { |
| 218 | struct pcb pcb; |
| 219 | |
| 220 | if (kvm_read (core_kd, (unsigned long) paddr, &pcb, sizeof pcb) == -1) |
| 221 | error (("%s"), kvm_geterr (core_kd)); |
| 222 | |
| 223 | gdb_assert (bsd_kvm_supply_pcb); |
| 224 | return bsd_kvm_supply_pcb (regcache, &pcb); |
| 225 | } |
| 226 | |
| 227 | void |
| 228 | bsd_kvm_target::fetch_registers (struct regcache *regcache, int regnum) |
| 229 | { |
| 230 | struct nlist nl[2]; |
| 231 | |
| 232 | if (bsd_kvm_paddr) |
| 233 | { |
| 234 | bsd_kvm_fetch_pcb (regcache, bsd_kvm_paddr); |
| 235 | return; |
| 236 | } |
| 237 | |
| 238 | /* On dumping core, BSD kernels store the faulting context (PCB) |
| 239 | in the variable "dumppcb". */ |
| 240 | memset (nl, 0, sizeof nl); |
| 241 | nl[0].n_name = "_dumppcb"; |
| 242 | |
| 243 | if (kvm_nlist (core_kd, nl) == -1) |
| 244 | error (("%s"), kvm_geterr (core_kd)); |
| 245 | |
| 246 | if (nl[0].n_value != 0) |
| 247 | { |
| 248 | /* Found dumppcb. If it contains a valid context, return |
| 249 | immediately. */ |
| 250 | if (bsd_kvm_fetch_pcb (regcache, (struct pcb *) nl[0].n_value)) |
| 251 | return; |
| 252 | } |
| 253 | |
| 254 | /* Traditional BSD kernels have a process proc0 that should always |
| 255 | be present. The address of proc0's PCB is stored in the variable |
| 256 | "proc0paddr". */ |
| 257 | |
| 258 | memset (nl, 0, sizeof nl); |
| 259 | nl[0].n_name = "_proc0paddr"; |
| 260 | |
| 261 | if (kvm_nlist (core_kd, nl) == -1) |
| 262 | error (("%s"), kvm_geterr (core_kd)); |
| 263 | |
| 264 | if (nl[0].n_value != 0) |
| 265 | { |
| 266 | struct pcb *paddr; |
| 267 | |
| 268 | /* Found proc0paddr. */ |
| 269 | if (kvm_read (core_kd, nl[0].n_value, &paddr, sizeof paddr) == -1) |
| 270 | error (("%s"), kvm_geterr (core_kd)); |
| 271 | |
| 272 | bsd_kvm_fetch_pcb (regcache, paddr); |
| 273 | return; |
| 274 | } |
| 275 | |
| 276 | #ifdef HAVE_STRUCT_THREAD_TD_PCB |
| 277 | /* In FreeBSD kernels for 5.0-RELEASE and later, the PCB no longer |
| 278 | lives in `struct proc' but in `struct thread'. The `struct |
| 279 | thread' for the initial thread for proc0 can be found in the |
| 280 | variable "thread0". */ |
| 281 | |
| 282 | memset (nl, 0, sizeof nl); |
| 283 | nl[0].n_name = "_thread0"; |
| 284 | |
| 285 | if (kvm_nlist (core_kd, nl) == -1) |
| 286 | error (("%s"), kvm_geterr (core_kd)); |
| 287 | |
| 288 | if (nl[0].n_value != 0) |
| 289 | { |
| 290 | struct pcb *paddr; |
| 291 | |
| 292 | /* Found thread0. */ |
| 293 | nl[0].n_value += offsetof (struct thread, td_pcb); |
| 294 | if (kvm_read (core_kd, nl[0].n_value, &paddr, sizeof paddr) == -1) |
| 295 | error (("%s"), kvm_geterr (core_kd)); |
| 296 | |
| 297 | bsd_kvm_fetch_pcb (regcache, paddr); |
| 298 | return; |
| 299 | } |
| 300 | #endif |
| 301 | |
| 302 | /* i18n: PCB == "Process Control Block". */ |
| 303 | error (_("Cannot find a valid PCB")); |
| 304 | } |
| 305 | \f |
| 306 | |
| 307 | /* Kernel memory interface commands. */ |
| 308 | struct cmd_list_element *bsd_kvm_cmdlist; |
| 309 | |
| 310 | static void |
| 311 | bsd_kvm_cmd (const char *arg, int fromtty) |
| 312 | { |
| 313 | /* ??? Should this become an alias for "target kvm"? */ |
| 314 | } |
| 315 | |
| 316 | #ifndef HAVE_STRUCT_THREAD_TD_PCB |
| 317 | |
| 318 | static void |
| 319 | bsd_kvm_proc_cmd (const char *arg, int fromtty) |
| 320 | { |
| 321 | CORE_ADDR addr; |
| 322 | |
| 323 | if (arg == NULL) |
| 324 | error_no_arg (_("proc address")); |
| 325 | |
| 326 | if (core_kd == NULL) |
| 327 | error (_("No kernel memory image.")); |
| 328 | |
| 329 | addr = parse_and_eval_address (arg); |
| 330 | #ifdef HAVE_STRUCT_LWP |
| 331 | addr += offsetof (struct lwp, l_addr); |
| 332 | #else |
| 333 | addr += offsetof (struct proc, p_addr); |
| 334 | #endif |
| 335 | |
| 336 | if (kvm_read (core_kd, addr, &bsd_kvm_paddr, sizeof bsd_kvm_paddr) == -1) |
| 337 | error (("%s"), kvm_geterr (core_kd)); |
| 338 | |
| 339 | target_fetch_registers (get_current_regcache (), -1); |
| 340 | |
| 341 | reinit_frame_cache (); |
| 342 | print_stack_frame (get_selected_frame (NULL), 0, SRC_AND_LOC, 1); |
| 343 | } |
| 344 | |
| 345 | #endif |
| 346 | |
| 347 | static void |
| 348 | bsd_kvm_pcb_cmd (const char *arg, int fromtty) |
| 349 | { |
| 350 | if (arg == NULL) |
| 351 | /* i18n: PCB == "Process Control Block". */ |
| 352 | error_no_arg (_("pcb address")); |
| 353 | |
| 354 | if (core_kd == NULL) |
| 355 | error (_("No kernel memory image.")); |
| 356 | |
| 357 | bsd_kvm_paddr = (struct pcb *)(u_long) parse_and_eval_address (arg); |
| 358 | |
| 359 | target_fetch_registers (get_current_regcache (), -1); |
| 360 | |
| 361 | reinit_frame_cache (); |
| 362 | print_stack_frame (get_selected_frame (NULL), 0, SRC_AND_LOC, 1); |
| 363 | } |
| 364 | |
| 365 | bool |
| 366 | bsd_kvm_target::thread_alive (ptid_t ptid) |
| 367 | { |
| 368 | return true; |
| 369 | } |
| 370 | |
| 371 | const char * |
| 372 | bsd_kvm_target::pid_to_str (ptid_t ptid) |
| 373 | { |
| 374 | static char buf[64]; |
| 375 | xsnprintf (buf, sizeof buf, "<kvm>"); |
| 376 | return buf; |
| 377 | } |
| 378 | |
| 379 | /* Add the libkvm interface to the list of all possible targets and |
| 380 | register CUPPLY_PCB as the architecture-specific process control |
| 381 | block interpreter. */ |
| 382 | |
| 383 | void |
| 384 | bsd_kvm_add_target (int (*supply_pcb)(struct regcache *, struct pcb *)) |
| 385 | { |
| 386 | gdb_assert (bsd_kvm_supply_pcb == NULL); |
| 387 | bsd_kvm_supply_pcb = supply_pcb; |
| 388 | |
| 389 | add_target (bsd_kvm_target_info, bsd_kvm_target_open); |
| 390 | |
| 391 | add_prefix_cmd ("kvm", class_obscure, bsd_kvm_cmd, _("\ |
| 392 | Generic command for manipulating the kernel memory interface."), |
| 393 | &bsd_kvm_cmdlist, "kvm ", 0, &cmdlist); |
| 394 | |
| 395 | #ifndef HAVE_STRUCT_THREAD_TD_PCB |
| 396 | add_cmd ("proc", class_obscure, bsd_kvm_proc_cmd, |
| 397 | _("Set current context from proc address"), &bsd_kvm_cmdlist); |
| 398 | #endif |
| 399 | add_cmd ("pcb", class_obscure, bsd_kvm_pcb_cmd, |
| 400 | /* i18n: PCB == "Process Control Block". */ |
| 401 | _("Set current context from pcb address"), &bsd_kvm_cmdlist); |
| 402 | |
| 403 | /* Some notes on the ptid usage on this target. |
| 404 | |
| 405 | The pid field represents the kvm inferior instance. Currently, |
| 406 | we don't support multiple kvm inferiors, but we start at 1 |
| 407 | anyway. The lwp field is set to != 0, in case the core wants to |
| 408 | refer to the whole kvm inferior with ptid(1,0,0). |
| 409 | |
| 410 | If kvm is made to export running processes as gdb threads, |
| 411 | the following form can be used: |
| 412 | ptid (1, 1, 0) -> kvm inferior 1, in kernel |
| 413 | ptid (1, 1, 1) -> kvm inferior 1, process 1 |
| 414 | ptid (1, 1, 2) -> kvm inferior 1, process 2 |
| 415 | ptid (1, 1, n) -> kvm inferior 1, process n */ |
| 416 | |
| 417 | bsd_kvm_ptid = ptid_t (1, 1, 0); |
| 418 | } |