usr/src/lib/libtnfctl/prb_rtld.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License, Version 1.0 only
   6  * (the "License").  You may not use this file except in compliance
   7  * with the License.
   8  *
   9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
  10  * or http://www.opensolaris.org/os/licensing.
  11  * See the License for the specific language governing permissions
  12  * and limitations under the License.
  13  *
  14  * When distributing Covered Code, include this CDDL HEADER in each
  15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  16  * If applicable, add the following below this CDDL HEADER, with the
  17  * fields enclosed by brackets "[]" replaced with your own identifying
  18  * information: Portions Copyright [yyyy] [name of copyright owner]
  19  *
  20  * CDDL HEADER END
  21  */
  22 /*
  23  * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27 #pragma ident   "%Z%%M% %I%     %E% SMI"
  28
  29 /*
  30  * Interfaces to sync up with run time linker (rtld) at process start up time
  31  * and at dlopen() and dlclose() time
  32  * In Solaris 2.6, librtld_db.so should replace this functionality.  Issues
  33  * to solve before libtnfctl.so can use librtld_db.so:
  34  * 1. Should libtnfctl.so be usable before Solaris 2.6 - If so, cannot use
  35  *    librtld_db.so
  36  * 2. libtnfctl.so will have to provide <proc_service.h> in order to use
  37  *    librtld_db.so.  If libtnfctl.so is now linked into a debugger that
  38  *    also provides <proc_service.h>, how will the two co-exist - will the
  39  *    linker get confused, or not ?
  40  */
  41
  42 #include <unistd.h>
  43 #include <stdlib.h>
  44 #include <string.h>
  45 #include <errno.h>
  46 #include <sys/types.h>
  47 #include <sys/stat.h>
  48 #include <sys/fcntl.h>
  49 #include <sys/procfs.h>
  50 #include <link.h>
  51
  52 #include "tnfctl.h"
  53 #include "prb_proc_int.h"
  54 #include "dbg.h"
  55
  56
  57 static prb_status_t prb_rtld_setup(prb_proc_ctl_t *proc_p, boolean_t *synced);
  58 static prb_status_t prb_rtld_wait(prb_proc_ctl_t *proc_p);
  59 static prb_status_t bpt(prb_proc_ctl_t *proc_p, uintptr_t addr);
  60 static prb_status_t unbpt(prb_proc_ctl_t *proc_p, uintptr_t addr);
  61
  62
  63 /* ---------------------------------------------------------------- */
  64 /* ----------------------- Public Functions ----------------------- */
  65 /* ---------------------------------------------------------------- */
  66
  67
  68 /*
  69  * prb_rtld_stalk() - setup for a breakpoint when rtld has opened or closed a
  70  * shared object.
  71  */
  72 prb_status_t
  73 prb_rtld_stalk(prb_proc_ctl_t *proc_p)
  74 {
  75         prb_status_t    prbstat = PRB_STATUS_OK;
  76
  77         DBG_TNF_PROBE_0(prb_rtld_stalk_1, "libtnfctl", "sunw%verbosity 2");
  78
  79         if (!proc_p->bptaddr) {
  80                 Elf3264_Dyn        dentry;
  81                 struct r_debug  r_dbg;
  82
  83                 if (proc_p->dbgaddr == 0) {
  84                         DBG((void) fprintf(stderr,
  85                                 "prb_rtld_stalk: dbgaddr not set\n"));
  86                         return (PRB_STATUS_BADARG);
  87                 }
  88
  89                 prbstat = prb_proc_read(proc_p, proc_p->dbgaddr,
  90                         &dentry, sizeof (dentry));
  91                 if (prbstat || !dentry.d_un.d_ptr) {
  92                         DBG((void) fprintf(stderr,
  93                                 "prb_rtld_stalk: error in d_un.d_ptr\n"));
  94                         return (prbstat);
  95                 }
  96                 /* read in the debug struct that it points to */
  97                 prbstat = prb_proc_read(proc_p, dentry.d_un.d_ptr,
  98                         &r_dbg, sizeof (r_dbg));
  99                 if (prbstat)
 100                         return (prbstat);
 101
 102                 proc_p->bptaddr = r_dbg.r_brk;
 103         }
 104         /* plant a breakpoint trap in the pointed to function */
 105         prbstat = bpt(proc_p, proc_p->bptaddr);
 106         if (prbstat)
 107                 return (prbstat);
 108
 109         /* setup process to stop when breakpoint encountered */
 110         prbstat = prb_proc_tracebpt(proc_p, B_TRUE);
 111
 112         return (prbstat);
 113
 114 }
 115
 116
 117 /*
 118  * prb_rtld_unstalk() - remove rtld breakpoint
 119  */
 120 prb_status_t
 121 prb_rtld_unstalk(prb_proc_ctl_t *proc_p)
 122 {
 123         prb_status_t    prbstat;
 124
 125         DBG_TNF_PROBE_0(prb_rtld_unstalk_1, "libtnfctl", "sunw%verbosity 2");
 126
 127         /* turn off BPT tracing while out of the water ... */
 128         prbstat = prb_proc_tracebpt(proc_p, B_FALSE);
 129
 130         prbstat = unbpt(proc_p, proc_p->bptaddr);
 131
 132         return (prbstat);
 133 }
 134
 135
 136 /*
 137  * prb_rtld_advance() - we've hit a breakpoint, replace the original
 138  * instruction, istep, put the breakpoint back ...
 139  */
 140 prb_status_t
 141 prb_rtld_advance(prb_proc_ctl_t *proc_p)
 142 {
 143         prb_status_t    prbstat;
 144
 145         DBG_TNF_PROBE_0(prb_rtld_advance_1, "libtnfctl", "sunw%verbosity 2");
 146
 147         prbstat = prb_proc_clrbptflt(proc_p);
 148         if (prbstat)
 149                 return (prbstat);
 150         prbstat = unbpt(proc_p, proc_p->bptaddr);
 151         if (prbstat)
 152                 return (prbstat);
 153
 154         prbstat = prb_proc_istepbpt(proc_p);
 155         if (prbstat)
 156                 return (prbstat);
 157
 158         prbstat = bpt(proc_p, proc_p->bptaddr);
 159         if (prbstat)
 160                 return (prbstat);
 161
 162         return (PRB_STATUS_OK);
 163 }
 164
 165 /*
 166  * checks if process has reached rtld_sync point or not i.e. has rltld
 167  * loaded in libraries or not ?  If not, it lets process run until
 168  * rtld has mapped in all libraries (no user code would have been
 169  * executed, including .init sections)
 170  */
 171 prb_status_t
 172 prb_rtld_sync_if_needed(prb_proc_ctl_t *proc_p)
 173 {
 174         prb_status_t    prbstat = PRB_STATUS_OK;
 175         boolean_t       synced = B_FALSE;
 176
 177         prbstat = prb_rtld_setup(proc_p, &synced);
 178         if (prbstat)
 179                 return (prbstat);
 180
 181         if (synced == B_FALSE) {
 182                 /* wait on target to sync up after rtld maps in all .so's */
 183                 prbstat = prb_rtld_wait(proc_p);
 184                 if (prbstat)
 185                         return (prbstat);
 186         }
 187
 188         return (prbstat);
 189 }
 190
 191 /* ---------------------------------------------------------------- */
 192 /* ----------------------- Private Functions ---------------------- */
 193 /* ---------------------------------------------------------------- */
 194
 195 /*
 196  * prb_rtld_setup() - turns on the flag in the rtld structure so that rtld
 197  * executes a getpid() stystem call after it done mapping all shared objects
 198  * but before it executes any init code.
 199  */
 200 static prb_status_t
 201 prb_rtld_setup(prb_proc_ctl_t *proc_p, boolean_t *synced)
 202 {
 203         prb_status_t    prbstat = PRB_STATUS_OK;
 204         Elf3264_Dyn     dentry;
 205
 206         DBG_TNF_PROBE_0(prb_rtld_setup_1, "libtnfctl", "sunw%verbosity 2");
 207
 208         if (proc_p->dbgaddr == 0) {
 209                 DBG((void) fprintf(stderr,
 210                         "prb_rtld_setup: dbgaddr not set\n"));
 211                 return (PRB_STATUS_BADARG);
 212         }
 213
 214         prbstat = prb_proc_read(proc_p, proc_p->dbgaddr, &dentry,
 215                                         sizeof (dentry));
 216         if (prbstat) {
 217                 DBG((void) fprintf(stderr,
 218                         "prb_rtld_setup: error in d_un.d_ptr\n"));
 219                 return (prbstat);
 220         }
 221
 222         if ((dentry.d_un.d_ptr == 0) || (dentry.d_un.d_ptr == 1)) {
 223                 *synced = B_FALSE;
 224         } else {
 225                 *synced = B_TRUE;
 226                 return (PRB_STATUS_OK);
 227         }
 228
 229         /* modify it  - i.e. request rtld to do getpid() */
 230         dentry.d_un.d_ptr = 1;
 231         prbstat = prb_proc_write(proc_p, proc_p->dbgaddr, &dentry,
 232                                         sizeof (dentry));
 233
 234         return (prbstat);
 235 }
 236
 237
 238 /*
 239  * prb_rtld_wait() - waits on target to execute getpid()
 240  */
 241 static prb_status_t
 242 prb_rtld_wait(prb_proc_ctl_t *proc_p)
 243 {
 244         prb_proc_state_t pstate;
 245         prb_status_t    prbstat;
 246
 247         DBG_TNF_PROBE_0(prb_rtld_wait_1, "libtnfctl", "sunw%verbosity 2");
 248
 249         /* stop on exit of getpid() */
 250         prbstat = prb_proc_exit(proc_p, SYS_getpid, PRB_SYS_ADD);
 251         if (prbstat) {
 252                 DBG((void) fprintf(stderr,
 253                         "prb_rtld_wait: couldn't set up child to stop on "
 254                         "exit of getpid(): %s\n", prb_status_str(prbstat)));
 255                 return (prbstat);
 256         }
 257         /* stop on entry of exit() - i.e. exec failed */
 258         prbstat = prb_proc_entry(proc_p, SYS_exit, PRB_SYS_ADD);
 259         if (prbstat) {
 260                 DBG((void) fprintf(stderr,
 261                         "prb_rtld_wait: couldn't set up child to stop on "
 262                         "entry of exit(): %s\n", prb_status_str(prbstat)));
 263                 return (prbstat);
 264         }
 265         /* continue target and wait for it to stop */
 266         prbstat = prb_proc_cont(proc_p);
 267         if (prbstat) {
 268                 DBG((void) fprintf(stderr,
 269                         "prb_rtld_wait: couldn't continue target process: %s\n",
 270                                 prb_status_str(prbstat)));
 271                 return (prbstat);
 272         }
 273         /* wait for target to stop */
 274         prbstat = prb_proc_wait(proc_p, B_FALSE, NULL);
 275         if (prbstat) {
 276                 DBG((void) fprintf(stderr,
 277                         "prb_rtld_wait: couldn't wait on target process: %s\n",
 278                         prb_status_str(prbstat)));
 279                 return (prbstat);
 280         }
 281         /* make sure it did stop on getpid() */
 282         prbstat = prb_proc_state(proc_p, &pstate);
 283         if (prbstat) {
 284                 DBG((void) fprintf(stderr,
 285                         "prb_rtld_wait: couldn't get state of target: %s\n",
 286                                 prb_status_str(prbstat)));
 287                 return (prbstat);
 288         }
 289         if (pstate.ps_issysentry && (pstate.ps_syscallnum == SYS_exit)) {
 290                 DBG((void) fprintf(stderr, "prb_rtld_wait: target exited\n"));
 291                 return (prb_status_map(EACCES));
 292         }
 293         /* catch any other errors */
 294         if (!(pstate.ps_issysexit && (pstate.ps_syscallnum == SYS_getpid))) {
 295                 DBG((void) fprintf(stderr,
 296                         "prb_rtld_wait: target didn't stop on getpid\n"));
 297                 return (PRB_STATUS_BADSYNC);
 298         }
 299         /* clear wait on getpid */
 300         prbstat = prb_proc_exit(proc_p, SYS_getpid, PRB_SYS_DEL);
 301         if (prbstat) {
 302                 DBG((void) fprintf(stderr,
 303                         "prb_rtld_wait: couldn't clear child to stop on "
 304                         "exit of getpid(): %s\n", prb_status_str(prbstat)));
 305                 return (prbstat);
 306         }
 307         /* clear wait on exit */
 308         prbstat = prb_proc_entry(proc_p, SYS_exit, PRB_SYS_DEL);
 309         if (prbstat) {
 310                 DBG((void) fprintf(stderr,
 311                         "prb_rtld_wait: couldn't clear child to stop on "
 312                         "entry of exit(): %s\n", prb_status_str(prbstat)));
 313                 return (prbstat);
 314         }
 315         /* start-stop the process to clear it out of the system call */
 316         prbstat = prb_proc_prstop(proc_p);
 317         if (prbstat) {
 318                 DBG((void) fprintf(stderr,
 319                         "prb_rtld_wait: couldn't prstop child: %s\n",
 320                         prb_status_str(prbstat)));
 321                 return (prbstat);
 322         }
 323         return (PRB_STATUS_OK);
 324 }
 325
 326
 327 #if defined(__sparc)
 328 #define INS_BPT 0x91d02001
 329 #elif defined(__i386) || defined(__amd64)
 330 #define INS_BPT 0xcc
 331 #else
 332 #error  What is your breakpoint instruction?
 333 #endif
 334
 335 /*
 336  * plants a breakpoint at the specified location in
 337  * the target process, and saves the existing instruction.
 338  */
 339 static prb_status_t
 340 bpt(prb_proc_ctl_t *proc_p, uintptr_t addr)
 341 {
 342         prb_status_t    prbstat;
 343         bptsave_t       instr;
 344
 345         if (!proc_p->bpt_inserted) {
 346
 347                 DBG_TNF_PROBE_1(bpt_1, "libtnfctl", "sunw%verbosity 2",
 348                         tnf_opaque, bpt_planted_at, addr);
 349
 350                 prbstat = prb_proc_read(proc_p, addr,
 351                         &(proc_p->saveinstr), sizeof (proc_p->saveinstr));
 352                 if (prbstat)
 353                         return (prbstat);
 354
 355                 DBG_TNF_PROBE_1(bpt_2, "libtnfctl", "sunw%verbosity 2",
 356                         tnf_opaque, saved_instr, (unsigned)proc_p->saveinstr);
 357
 358                 instr = INS_BPT;
 359
 360                 prbstat = prb_proc_write(proc_p, addr,
 361                         &instr, sizeof (instr));
 362                 if (prbstat)
 363                         return (prbstat);
 364
 365                 proc_p->bpt_inserted = B_TRUE;
 366         }
 367         return (PRB_STATUS_OK);
 368 }
 369
 370 /*
 371  * removes  a breakpoint at the specified location in
 372  * the target process, and replaces it with the original instruction.
 373  */
 374 prb_status_t
 375 unbpt(prb_proc_ctl_t *proc_p, uintptr_t addr)
 376 {
 377         prb_status_t    prbstat;
 378
 379         if (proc_p->bpt_inserted) {
 380
 381                 DBG_TNF_PROBE_2(unbpt_1, "libtnfctl", "sunw%verbosity 2",
 382                         tnf_opaque, unplanting_at, addr,
 383                         tnf_opaque, saved_instr, (unsigned)proc_p->saveinstr);
 384
 385                 prbstat = prb_proc_write(proc_p, addr, &(proc_p->saveinstr),
 386                         sizeof (proc_p->saveinstr));
 387                 if (prbstat)
 388                         return (prbstat);
 389
 390                 proc_p->bpt_inserted = B_FALSE;
 391         }
 392         return (PRB_STATUS_OK);
 393 }