sys/kern/sys_process.c

   1 /*-
   2  * Copyright (c) 1994, Sean Eric Fagan
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by Sean Eric Fagan.
  16  * 4. The name of the author may not be used to endorse or promote products
  17  *    derived from this software without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  29  * SUCH DAMAGE.
  30  */
  31
  32 #include <sys/cdefs.h>
  33 __FBSDID("$FreeBSD$");
  34
  35 #include <sys/param.h>
  36 #include <sys/systm.h>
  37 #include <sys/lock.h>
  38 #include <sys/mutex.h>
  39 #include <sys/syscallsubr.h>
  40 #include <sys/sysproto.h>
  41 #include <sys/proc.h>
  42 #include <sys/vnode.h>
  43 #include <sys/ptrace.h>
  44 #include <sys/sx.h>
  45 #include <sys/malloc.h>
  46 #include <sys/signalvar.h>
  47
  48 #include <machine/reg.h>
  49
  50 #include <vm/vm.h>
  51 #include <vm/pmap.h>
  52 #include <vm/vm_extern.h>
  53 #include <vm/vm_map.h>
  54 #include <vm/vm_kern.h>
  55 #include <vm/vm_object.h>
  56 #include <vm/vm_page.h>
  57
  58 /*
  59  * Functions implemented using PROC_ACTION():
  60  *
  61  * proc_read_regs(proc, regs)
  62  *      Get the current user-visible register set from the process
  63  *      and copy it into the regs structure (<machine/reg.h>).
  64  *      The process is stopped at the time read_regs is called.
  65  *
  66  * proc_write_regs(proc, regs)
  67  *      Update the current register set from the passed in regs
  68  *      structure.  Take care to avoid clobbering special CPU
  69  *      registers or privileged bits in the PSL.
  70  *      Depending on the architecture this may have fix-up work to do,
  71  *      especially if the IAR or PCW are modified.
  72  *      The process is stopped at the time write_regs is called.
  73  *
  74  * proc_read_fpregs, proc_write_fpregs
  75  *      deal with the floating point register set, otherwise as above.
  76  *
  77  * proc_read_dbregs, proc_write_dbregs
  78  *      deal with the processor debug register set, otherwise as above.
  79  *
  80  * proc_sstep(proc)
  81  *      Arrange for the process to trap after executing a single instruction.
  82  */
  83
  84 #define PROC_ACTION(action) do {                                        \
  85         int error;                                                      \
  86                                                                         \
  87         PROC_LOCK_ASSERT(td->td_proc, MA_OWNED);                        \
  88         if ((td->td_proc->p_sflag & PS_INMEM) == 0)                     \
  89                 error = EIO;                                            \
  90         else                                                            \
  91                 error = (action);                                       \
  92         return (error);                                                 \
  93 } while(0)
  94
  95 int
  96 proc_read_regs(struct thread *td, struct reg *regs)
  97 {
  98
  99         PROC_ACTION(fill_regs(td, regs));
 100 }
 101
 102 int
 103 proc_write_regs(struct thread *td, struct reg *regs)
 104 {
 105
 106         PROC_ACTION(set_regs(td, regs));
 107 }
 108
 109 int
 110 proc_read_dbregs(struct thread *td, struct dbreg *dbregs)
 111 {
 112
 113         PROC_ACTION(fill_dbregs(td, dbregs));
 114 }
 115
 116 int
 117 proc_write_dbregs(struct thread *td, struct dbreg *dbregs)
 118 {
 119
 120         PROC_ACTION(set_dbregs(td, dbregs));
 121 }
 122
 123 /*
 124  * Ptrace doesn't support fpregs at all, and there are no security holes
 125  * or translations for fpregs, so we can just copy them.
 126  */
 127 int
 128 proc_read_fpregs(struct thread *td, struct fpreg *fpregs)
 129 {
 130
 131         PROC_ACTION(fill_fpregs(td, fpregs));
 132 }
 133
 134 int
 135 proc_write_fpregs(struct thread *td, struct fpreg *fpregs)
 136 {
 137
 138         PROC_ACTION(set_fpregs(td, fpregs));
 139 }
 140
 141 int
 142 proc_sstep(struct thread *td)
 143 {
 144
 145         PROC_ACTION(ptrace_single_step(td));
 146 }
 147
 148 int
 149 proc_rwmem(struct proc *p, struct uio *uio)
 150 {
 151         struct vmspace *vm;
 152         vm_map_t map;
 153         vm_object_t backing_object, object = NULL;
 154         vm_offset_t pageno = 0;         /* page number */
 155         vm_prot_t reqprot;
 156         int error, refcnt, writing;
 157
 158         /*
 159          * if the vmspace is in the midst of being deallocated or the
 160          * process is exiting, don't try to grab anything.  The page table
 161          * usage in that process can be messed up.
 162          */
 163         vm = p->p_vmspace;
 164         if ((p->p_flag & P_WEXIT))
 165                 return (EFAULT);
 166         do {
 167                 if ((refcnt = vm->vm_refcnt) < 1)
 168                         return (EFAULT);
 169         } while (!atomic_cmpset_int(&vm->vm_refcnt, refcnt, refcnt + 1));
 170
 171         /*
 172          * The map we want...
 173          */
 174         map = &vm->vm_map;
 175
 176         writing = uio->uio_rw == UIO_WRITE;
 177         reqprot = writing ? (VM_PROT_WRITE | VM_PROT_OVERRIDE_WRITE) :
 178             VM_PROT_READ;
 179
 180         /*
 181          * Only map in one page at a time.  We don't have to, but it
 182          * makes things easier.  This way is trivial - right?
 183          */
 184         do {
 185                 vm_map_t tmap;
 186                 vm_offset_t uva;
 187                 int page_offset;                /* offset into page */
 188                 vm_map_entry_t out_entry;
 189                 vm_prot_t out_prot;
 190                 boolean_t wired;
 191                 vm_pindex_t pindex;
 192                 u_int len;
 193                 vm_page_t m;
 194
 195                 object = NULL;
 196
 197                 uva = (vm_offset_t)uio->uio_offset;
 198
 199                 /*
 200                  * Get the page number of this segment.
 201                  */
 202                 pageno = trunc_page(uva);
 203                 page_offset = uva - pageno;
 204
 205                 /*
 206                  * How many bytes to copy
 207                  */
 208                 len = min(PAGE_SIZE - page_offset, uio->uio_resid);
 209
 210                 /*
 211                  * Fault the page on behalf of the process
 212                  */
 213                 error = vm_fault(map, pageno, reqprot, VM_FAULT_NORMAL);
 214                 if (error) {
 215                         error = EFAULT;
 216                         break;
 217                 }
 218
 219                 /*
 220                  * Now we need to get the page.  out_entry, out_prot, wired,
 221                  * and single_use aren't used.  One would think the vm code
 222                  * would be a *bit* nicer...  We use tmap because
 223                  * vm_map_lookup() can change the map argument.
 224                  */
 225                 tmap = map;
 226                 error = vm_map_lookup(&tmap, pageno, reqprot, &out_entry,
 227                     &object, &pindex, &out_prot, &wired);
 228                 if (error) {
 229                         error = EFAULT;
 230                         break;
 231                 }
 232                 VM_OBJECT_LOCK(object);
 233                 while ((m = vm_page_lookup(object, pindex)) == NULL &&
 234                     !writing &&
 235                     (backing_object = object->backing_object) != NULL) {
 236                         /*
 237                          * Allow fallback to backing objects if we are reading.
 238                          */
 239                         VM_OBJECT_LOCK(backing_object);
 240                         pindex += OFF_TO_IDX(object->backing_object_offset);
 241                         VM_OBJECT_UNLOCK(object);
 242                         object = backing_object;
 243                 }
 244                 VM_OBJECT_UNLOCK(object);
 245                 if (m == NULL) {
 246                         vm_map_lookup_done(tmap, out_entry);
 247                         error = EFAULT;
 248                         break;
 249                 }
 250
 251                 /*
 252                  * Hold the page in memory.
 253                  */
 254                 vm_page_lock_queues();
 255                 vm_page_hold(m);
 256                 vm_page_unlock_queues();
 257
 258                 /*
 259                  * We're done with tmap now.
 260                  */
 261                 vm_map_lookup_done(tmap, out_entry);
 262
 263                 /*
 264                  * Now do the i/o move.
 265                  */
 266                 error = uiomove_fromphys(&m, page_offset, len, uio);
 267
 268                 /*
 269                  * Release the page.
 270                  */
 271                 vm_page_lock_queues();
 272                 vm_page_unhold(m);
 273                 vm_page_unlock_queues();
 274
 275         } while (error == 0 && uio->uio_resid > 0);
 276
 277         vmspace_free(vm);
 278         return (error);
 279 }
 280
 281 /*
 282  * Process debugging system call.
 283  */
 284 #ifndef _SYS_SYSPROTO_H_
 285 struct ptrace_args {
 286         int     req;
 287         pid_t   pid;
 288         caddr_t addr;
 289         int     data;
 290 };
 291 #endif
 292
 293 /*
 294  * MPSAFE
 295  */
 296 int
 297 ptrace(struct thread *td, struct ptrace_args *uap)
 298 {
 299         /*
 300          * XXX this obfuscation is to reduce stack usage, but the register
 301          * structs may be too large to put on the stack anyway.
 302          */
 303         union {
 304                 struct ptrace_io_desc piod;
 305                 struct ptrace_lwpinfo pl;
 306                 struct dbreg dbreg;
 307                 struct fpreg fpreg;
 308                 struct reg reg;
 309         } r;
 310         void *addr;
 311         int error = 0;
 312
 313         addr = &r;
 314         switch (uap->req) {
 315         case PT_GETREGS:
 316         case PT_GETFPREGS:
 317         case PT_GETDBREGS:
 318         case PT_LWPINFO:
 319                 break;
 320         case PT_SETREGS:
 321                 error = copyin(uap->addr, &r.reg, sizeof r.reg);
 322                 break;
 323         case PT_SETFPREGS:
 324                 error = copyin(uap->addr, &r.fpreg, sizeof r.fpreg);
 325                 break;
 326         case PT_SETDBREGS:
 327                 error = copyin(uap->addr, &r.dbreg, sizeof r.dbreg);
 328                 break;
 329         case PT_IO:
 330                 error = copyin(uap->addr, &r.piod, sizeof r.piod);
 331                 break;
 332         default:
 333                 addr = uap->addr;
 334                 break;
 335         }
 336         if (error)
 337                 return (error);
 338
 339         error = kern_ptrace(td, uap->req, uap->pid, addr, uap->data);
 340         if (error)
 341                 return (error);
 342
 343         switch (uap->req) {
 344         case PT_IO:
 345                 (void)copyout(&r.piod, uap->addr, sizeof r.piod);
 346                 break;
 347         case PT_GETREGS:
 348                 error = copyout(&r.reg, uap->addr, sizeof r.reg);
 349                 break;
 350         case PT_GETFPREGS:
 351                 error = copyout(&r.fpreg, uap->addr, sizeof r.fpreg);
 352                 break;
 353         case PT_GETDBREGS:
 354                 error = copyout(&r.dbreg, uap->addr, sizeof r.dbreg);
 355                 break;
 356         case PT_LWPINFO:
 357                 error = copyout(&r.pl, uap->addr, uap->data);
 358                 break;
 359         }
 360
 361         return (error);
 362 }
 363
 364 int
 365 kern_ptrace(struct thread *td, int req, pid_t pid, void *addr, int data)
 366 {
 367         struct iovec iov;
 368         struct uio uio;
 369         struct proc *curp, *p, *pp;
 370         struct thread *td2 = NULL;
 371         struct ptrace_io_desc *piod;
 372         struct ptrace_lwpinfo *pl;
 373         int error, write, tmp, num;
 374         int proctree_locked = 0;
 375         lwpid_t tid = 0, *buf;
 376         pid_t saved_pid = pid;
 377
 378         curp = td->td_proc;
 379
 380         /* Lock proctree before locking the process. */
 381         switch (req) {
 382         case PT_TRACE_ME:
 383         case PT_ATTACH:
 384         case PT_STEP:
 385         case PT_CONTINUE:
 386         case PT_TO_SCE:
 387         case PT_TO_SCX:
 388         case PT_SYSCALL:
 389         case PT_DETACH:
 390                 sx_xlock(&proctree_lock);
 391                 proctree_locked = 1;
 392                 break;
 393         default:
 394                 break;
 395         }
 396
 397         write = 0;
 398         if (req == PT_TRACE_ME) {
 399                 p = td->td_proc;
 400                 PROC_LOCK(p);
 401         } else {
 402                 if (pid <= PID_MAX) {
 403                         if ((p = pfind(pid)) == NULL) {
 404                                 if (proctree_locked)
 405                                         sx_xunlock(&proctree_lock);
 406                                 return (ESRCH);
 407                         }
 408                 } else {
 409                         /* this is slow, should be optimized */
 410                         sx_slock(&allproc_lock);
 411                         FOREACH_PROC_IN_SYSTEM(p) {
 412                                 PROC_LOCK(p);
 413                                 mtx_lock_spin(&sched_lock);
 414                                 FOREACH_THREAD_IN_PROC(p, td2) {
 415                                         if (td2->td_tid == pid)
 416                                                 break;
 417                                 }
 418                                 mtx_unlock_spin(&sched_lock);
 419                                 if (td2 != NULL)
 420                                         break; /* proc lock held */
 421                                 PROC_UNLOCK(p);
 422                         }
 423                         sx_sunlock(&allproc_lock);
 424                         if (p == NULL) {
 425                                 if (proctree_locked)
 426                                         sx_xunlock(&proctree_lock);
 427                                 return (ESRCH);
 428                         }
 429                         tid = pid;
 430                         pid = p->p_pid;
 431                 }
 432         }
 433         if ((error = p_cansee(td, p)) != 0)
 434                 goto fail;
 435
 436         if ((error = p_candebug(td, p)) != 0)
 437                 goto fail;
 438
 439         /*
 440          * System processes can't be debugged.
 441          */
 442         if ((p->p_flag & P_SYSTEM) != 0) {
 443                 error = EINVAL;
 444                 goto fail;
 445         }
 446
 447         if (tid == 0) {
 448                 td2 = FIRST_THREAD_IN_PROC(p);
 449                 tid = td2->td_tid;
 450         }
 451
 452         /*
 453          * Permissions check
 454          */
 455         switch (req) {
 456         case PT_TRACE_ME:
 457                 /* Always legal. */
 458                 break;
 459
 460         case PT_ATTACH:
 461                 /* Self */
 462                 if (p->p_pid == td->td_proc->p_pid) {
 463                         error = EINVAL;
 464                         goto fail;
 465                 }
 466
 467                 /* Already traced */
 468                 if (p->p_flag & P_TRACED) {
 469                         error = EBUSY;
 470                         goto fail;
 471                 }
 472
 473                 /* Can't trace an ancestor if you're being traced. */
 474                 if (curp->p_flag & P_TRACED) {
 475                         for (pp = curp->p_pptr; pp != NULL; pp = pp->p_pptr) {
 476                                 if (pp == p) {
 477                                         error = EINVAL;
 478                                         goto fail;
 479                                 }
 480                         }
 481                 }
 482
 483
 484                 /* OK */
 485                 break;
 486
 487         case PT_CLEARSTEP:
 488                 /* Allow thread to clear single step for itself */
 489                 if (td->td_tid == tid)
 490                         break;
 491
 492                 /* FALLTHROUGH */
 493         default:
 494                 /* not being traced... */
 495                 if ((p->p_flag & P_TRACED) == 0) {
 496                         error = EPERM;
 497                         goto fail;
 498                 }
 499
 500                 /* not being traced by YOU */
 501                 if (p->p_pptr != td->td_proc) {
 502                         error = EBUSY;
 503                         goto fail;
 504                 }
 505
 506                 /* not currently stopped */
 507                 if (!P_SHOULDSTOP(p) || p->p_suspcount != p->p_numthreads ||
 508                     (p->p_flag & P_WAITED) == 0) {
 509                         error = EBUSY;
 510                         goto fail;
 511                 }
 512
 513                 /* OK */
 514                 break;
 515         }
 516
 517 #ifdef FIX_SSTEP
 518         /*
 519          * Single step fixup ala procfs
 520          */
 521         FIX_SSTEP(td2);                 /* XXXKSE */
 522 #endif
 523
 524         /*
 525          * Actually do the requests
 526          */
 527
 528         td->td_retval[0] = 0;
 529
 530         switch (req) {
 531         case PT_TRACE_ME:
 532                 /* set my trace flag and "owner" so it can read/write me */
 533                 p->p_flag |= P_TRACED;
 534                 p->p_oppid = p->p_pptr->p_pid;
 535                 PROC_UNLOCK(p);
 536                 sx_xunlock(&proctree_lock);
 537                 return (0);
 538
 539         case PT_ATTACH:
 540                 /* security check done above */
 541                 p->p_flag |= P_TRACED;
 542                 p->p_oppid = p->p_pptr->p_pid;
 543                 if (p->p_pptr != td->td_proc)
 544                         proc_reparent(p, td->td_proc);
 545                 data = SIGSTOP;
 546                 goto sendsig;   /* in PT_CONTINUE below */
 547
 548         case PT_CLEARSTEP:
 549                 _PHOLD(p);
 550                 error = ptrace_clear_single_step(td2);
 551                 _PRELE(p);
 552                 if (error)
 553                         goto fail;
 554                 PROC_UNLOCK(p);
 555                 return (0);
 556
 557         case PT_SETSTEP:
 558                 _PHOLD(p);
 559                 error = ptrace_single_step(td2);
 560                 _PRELE(p);
 561                 if (error)
 562                         goto fail;
 563                 PROC_UNLOCK(p);
 564                 return (0);
 565
 566         case PT_SUSPEND:
 567                 _PHOLD(p);
 568                 mtx_lock_spin(&sched_lock);
 569                 td2->td_flags |= TDF_DBSUSPEND;
 570                 mtx_unlock_spin(&sched_lock);
 571                 _PRELE(p);
 572                 PROC_UNLOCK(p);
 573                 return (0);
 574
 575         case PT_RESUME:
 576                 _PHOLD(p);
 577                 mtx_lock_spin(&sched_lock);
 578                 td2->td_flags &= ~TDF_DBSUSPEND;
 579                 mtx_unlock_spin(&sched_lock);
 580                 _PRELE(p);
 581                 PROC_UNLOCK(p);
 582                 return (0);
 583
 584         case PT_STEP:
 585         case PT_CONTINUE:
 586         case PT_TO_SCE:
 587         case PT_TO_SCX:
 588         case PT_SYSCALL:
 589         case PT_DETACH:
 590                 /* Zero means do not send any signal */
 591                 if (data < 0 || data > _SIG_MAXSIG) {
 592                         error = EINVAL;
 593                         goto fail;
 594                 }
 595
 596                 _PHOLD(p);
 597
 598                 switch (req) {
 599                 case PT_STEP:
 600                         PROC_UNLOCK(p);
 601                         error = ptrace_single_step(td2);
 602                         if (error) {
 603                                 PRELE(p);
 604                                 goto fail_noproc;
 605                         }
 606                         PROC_LOCK(p);
 607                         break;
 608                 case PT_TO_SCE:
 609                         p->p_stops |= S_PT_SCE;
 610                         break;
 611                 case PT_TO_SCX:
 612                         p->p_stops |= S_PT_SCX;
 613                         break;
 614                 case PT_SYSCALL:
 615                         p->p_stops |= S_PT_SCE | S_PT_SCX;
 616                         break;
 617                 }
 618
 619                 if (addr != (void *)1) {
 620                         PROC_UNLOCK(p);
 621                         error = ptrace_set_pc(td2, (u_long)(uintfptr_t)addr);
 622                         if (error) {
 623                                 PRELE(p);
 624                                 goto fail_noproc;
 625                         }
 626                         PROC_LOCK(p);
 627                 }
 628                 _PRELE(p);
 629
 630                 if (req == PT_DETACH) {
 631                         /* reset process parent */
 632                         if (p->p_oppid != p->p_pptr->p_pid) {
 633                                 struct proc *pp;
 634
 635                                 PROC_UNLOCK(p);
 636                                 pp = pfind(p->p_oppid);
 637                                 if (pp == NULL)
 638                                         pp = initproc;
 639                                 else
 640                                         PROC_UNLOCK(pp);
 641                                 PROC_LOCK(p);
 642                                 proc_reparent(p, pp);
 643                                 if (pp == initproc)
 644                                         p->p_sigparent = SIGCHLD;
 645                         }
 646                         p->p_flag &= ~(P_TRACED | P_WAITED);
 647                         p->p_oppid = 0;
 648
 649                         /* should we send SIGCHLD? */
 650                 }
 651
 652         sendsig:
 653                 if (proctree_locked)
 654                         sx_xunlock(&proctree_lock);
 655                 /* deliver or queue signal */
 656                 if (P_SHOULDSTOP(p)) {
 657                         p->p_xstat = data;
 658                         p->p_flag &= ~(P_STOPPED_TRACE|P_STOPPED_SIG);
 659                         mtx_lock_spin(&sched_lock);
 660                         if (saved_pid <= PID_MAX) {
 661                                 p->p_xthread->td_flags &= ~TDF_XSIG;
 662                                 p->p_xthread->td_xsig = data;
 663                         } else {
 664                                 td2->td_flags &= ~TDF_XSIG;
 665                                 td2->td_xsig = data;
 666                         }
 667                         p->p_xthread = NULL;
 668                         if (req == PT_DETACH) {
 669                                 struct thread *td3;
 670                                 FOREACH_THREAD_IN_PROC(p, td3)
 671                                         td3->td_flags &= ~TDF_DBSUSPEND;
 672                         }
 673                         /*
 674                          * unsuspend all threads, to not let a thread run,
 675                          * you should use PT_SUSPEND to suspend it before
 676                          * continuing process.
 677                          */
 678                         thread_unsuspend(p);
 679                         thread_continued(p);
 680                         mtx_unlock_spin(&sched_lock);
 681                 } else if (data) {
 682                         psignal(p, data);
 683                 }
 684                 PROC_UNLOCK(p);
 685
 686                 return (0);
 687
 688         case PT_WRITE_I:
 689         case PT_WRITE_D:
 690                 write = 1;
 691                 /* FALLTHROUGH */
 692         case PT_READ_I:
 693         case PT_READ_D:
 694                 PROC_UNLOCK(p);
 695                 tmp = 0;
 696                 /* write = 0 set above */
 697                 iov.iov_base = write ? (caddr_t)&data : (caddr_t)&tmp;
 698                 iov.iov_len = sizeof(int);
 699                 uio.uio_iov = &iov;
 700                 uio.uio_iovcnt = 1;
 701                 uio.uio_offset = (off_t)(uintptr_t)addr;
 702                 uio.uio_resid = sizeof(int);
 703                 uio.uio_segflg = UIO_SYSSPACE;  /* i.e.: the uap */
 704                 uio.uio_rw = write ? UIO_WRITE : UIO_READ;
 705                 uio.uio_td = td;
 706                 error = proc_rwmem(p, &uio);
 707                 if (uio.uio_resid != 0) {
 708                         /*
 709                          * XXX proc_rwmem() doesn't currently return ENOSPC,
 710                          * so I think write() can bogusly return 0.
 711                          * XXX what happens for short writes?  We don't want
 712                          * to write partial data.
 713                          * XXX proc_rwmem() returns EPERM for other invalid
 714                          * addresses.  Convert this to EINVAL.  Does this
 715                          * clobber returns of EPERM for other reasons?
 716                          */
 717                         if (error == 0 || error == ENOSPC || error == EPERM)
 718                                 error = EINVAL; /* EOF */
 719                 }
 720                 if (!write)
 721                         td->td_retval[0] = tmp;
 722                 return (error);
 723
 724         case PT_IO:
 725                 PROC_UNLOCK(p);
 726                 piod = addr;
 727                 iov.iov_base = piod->piod_addr;
 728                 iov.iov_len = piod->piod_len;
 729                 uio.uio_iov = &iov;
 730                 uio.uio_iovcnt = 1;
 731                 uio.uio_offset = (off_t)(uintptr_t)piod->piod_offs;
 732                 uio.uio_resid = piod->piod_len;
 733                 uio.uio_segflg = UIO_USERSPACE;
 734                 uio.uio_td = td;
 735                 switch (piod->piod_op) {
 736                 case PIOD_READ_D:
 737                 case PIOD_READ_I:
 738                         uio.uio_rw = UIO_READ;
 739                         break;
 740                 case PIOD_WRITE_D:
 741                 case PIOD_WRITE_I:
 742                         uio.uio_rw = UIO_WRITE;
 743                         break;
 744                 default:
 745                         return (EINVAL);
 746                 }
 747                 error = proc_rwmem(p, &uio);
 748                 piod->piod_len -= uio.uio_resid;
 749                 return (error);
 750
 751         case PT_KILL:
 752                 data = SIGKILL;
 753                 goto sendsig;   /* in PT_CONTINUE above */
 754
 755         case PT_SETREGS:
 756                 _PHOLD(p);
 757                 error = proc_write_regs(td2, addr);
 758                 _PRELE(p);
 759                 PROC_UNLOCK(p);
 760                 return (error);
 761
 762         case PT_GETREGS:
 763                 _PHOLD(p);
 764                 error = proc_read_regs(td2, addr);
 765                 _PRELE(p);
 766                 PROC_UNLOCK(p);
 767                 return (error);
 768
 769         case PT_SETFPREGS:
 770                 _PHOLD(p);
 771                 error = proc_write_fpregs(td2, addr);
 772                 _PRELE(p);
 773                 PROC_UNLOCK(p);
 774                 return (error);
 775
 776         case PT_GETFPREGS:
 777                 _PHOLD(p);
 778                 error = proc_read_fpregs(td2, addr);
 779                 _PRELE(p);
 780                 PROC_UNLOCK(p);
 781                 return (error);
 782
 783         case PT_SETDBREGS:
 784                 _PHOLD(p);
 785                 error = proc_write_dbregs(td2, addr);
 786                 _PRELE(p);
 787                 PROC_UNLOCK(p);
 788                 return (error);
 789
 790         case PT_GETDBREGS:
 791                 _PHOLD(p);
 792                 error = proc_read_dbregs(td2, addr);
 793                 _PRELE(p);
 794                 PROC_UNLOCK(p);
 795                 return (error);
 796
 797         case PT_LWPINFO:
 798                 if (data == 0 || data > sizeof(*pl))
 799                         return (EINVAL);
 800                 pl = addr;
 801                 _PHOLD(p);
 802                 if (saved_pid <= PID_MAX) {
 803                         pl->pl_lwpid = p->p_xthread->td_tid;
 804                         pl->pl_event = PL_EVENT_SIGNAL;
 805                 } else {
 806                         pl->pl_lwpid = td2->td_tid;
 807                         if (td2->td_flags & TDF_XSIG)
 808                                 pl->pl_event = PL_EVENT_SIGNAL;
 809                         else
 810                                 pl->pl_event = 0;
 811                 }
 812                 if (td2->td_pflags & TDP_SA) {
 813                         pl->pl_flags = PL_FLAG_SA;
 814                         if (td2->td_upcall && !TD_CAN_UNBIND(td2))
 815                                 pl->pl_flags |= PL_FLAG_BOUND;
 816                 } else {
 817                         pl->pl_flags = 0;
 818                 }
 819                 _PRELE(p);
 820                 PROC_UNLOCK(p);
 821                 return (0);
 822
 823         case PT_GETNUMLWPS:
 824                 td->td_retval[0] = p->p_numthreads;
 825                 PROC_UNLOCK(p);
 826                 return (0);
 827
 828         case PT_GETLWPLIST:
 829                 if (data <= 0) {
 830                         PROC_UNLOCK(p);
 831                         return (EINVAL);
 832                 }
 833                 num = imin(p->p_numthreads, data);
 834                 PROC_UNLOCK(p);
 835                 buf = malloc(num * sizeof(lwpid_t), M_TEMP, M_WAITOK);
 836                 tmp = 0;
 837                 PROC_LOCK(p);
 838                 mtx_lock_spin(&sched_lock);
 839                 FOREACH_THREAD_IN_PROC(p, td2) {
 840                         if (tmp >= num)
 841                                 break;
 842                         buf[tmp++] = td2->td_tid;
 843                 }
 844                 mtx_unlock_spin(&sched_lock);
 845                 PROC_UNLOCK(p);
 846                 error = copyout(buf, addr, tmp * sizeof(lwpid_t));
 847                 free(buf, M_TEMP);
 848                 if (!error)
 849                         td->td_retval[0] = num;
 850                 return (error);
 851
 852         default:
 853 #ifdef __HAVE_PTRACE_MACHDEP
 854                 if (req >= PT_FIRSTMACH) {
 855                         _PHOLD(p);
 856                         PROC_UNLOCK(p);
 857                         error = cpu_ptrace(td2, req, addr, data);
 858                         PRELE(p);
 859                         return (error);
 860                 }
 861 #endif
 862                 break;
 863         }
 864
 865         /* Unknown request. */
 866         error = EINVAL;
 867
 868 fail:
 869         PROC_UNLOCK(p);
 870 fail_noproc:
 871         if (proctree_locked)
 872                 sx_xunlock(&proctree_lock);
 873         return (error);
 874 }
 875
 876 /*
 877  * Stop a process because of a debugging event;
 878  * stay stopped until p->p_step is cleared
 879  * (cleared by PIOCCONT in procfs).
 880  */
 881 void
 882 stopevent(struct proc *p, unsigned int event, unsigned int val)
 883 {
 884
 885         PROC_LOCK_ASSERT(p, MA_OWNED);
 886         p->p_step = 1;
 887         do {
 888                 p->p_xstat = val;
 889                 p->p_xthread = NULL;
 890                 p->p_stype = event;     /* Which event caused the stop? */
 891                 wakeup(&p->p_stype);    /* Wake up any PIOCWAIT'ing procs */
 892                 msleep(&p->p_step, &p->p_mtx, PWAIT, "stopevent", 0);
 893         } while (p->p_step);
 894 }