sys/kern/sys_process.c

   1 /*-
   2  * SPDX-License-Identifier: BSD-4-Clause
   3  *
   4  * Copyright (c) 1994, Sean Eric Fagan
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 3. All advertising materials mentioning features or use of this software
  16  *    must display the following acknowledgement:
  17  *      This product includes software developed by Sean Eric Fagan.
  18  * 4. The name of the author may not be used to endorse or promote products
  19  *    derived from this software without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33
  34 #include <sys/cdefs.h>
  35 __FBSDID("$FreeBSD$");
  36
  37 #include <sys/param.h>
  38 #include <sys/systm.h>
  39 #include <sys/ktr.h>
  40 #include <sys/limits.h>
  41 #include <sys/lock.h>
  42 #include <sys/mutex.h>
  43 #include <sys/syscallsubr.h>
  44 #include <sys/sysent.h>
  45 #include <sys/sysproto.h>
  46 #include <sys/priv.h>
  47 #include <sys/proc.h>
  48 #include <sys/vnode.h>
  49 #include <sys/ptrace.h>
  50 #include <sys/rwlock.h>
  51 #include <sys/sx.h>
  52 #include <sys/malloc.h>
  53 #include <sys/signalvar.h>
  54
  55 #include <machine/reg.h>
  56
  57 #include <security/audit/audit.h>
  58
  59 #include <vm/vm.h>
  60 #include <vm/pmap.h>
  61 #include <vm/vm_extern.h>
  62 #include <vm/vm_map.h>
  63 #include <vm/vm_kern.h>
  64 #include <vm/vm_object.h>
  65 #include <vm/vm_page.h>
  66 #include <vm/vm_param.h>
  67
  68 #ifdef COMPAT_FREEBSD32
  69 #include <sys/procfs.h>
  70 #endif
  71
  72 /*
  73  * Functions implemented using PROC_ACTION():
  74  *
  75  * proc_read_regs(proc, regs)
  76  *      Get the current user-visible register set from the process
  77  *      and copy it into the regs structure (<machine/reg.h>).
  78  *      The process is stopped at the time read_regs is called.
  79  *
  80  * proc_write_regs(proc, regs)
  81  *      Update the current register set from the passed in regs
  82  *      structure.  Take care to avoid clobbering special CPU
  83  *      registers or privileged bits in the PSL.
  84  *      Depending on the architecture this may have fix-up work to do,
  85  *      especially if the IAR or PCW are modified.
  86  *      The process is stopped at the time write_regs is called.
  87  *
  88  * proc_read_fpregs, proc_write_fpregs
  89  *      deal with the floating point register set, otherwise as above.
  90  *
  91  * proc_read_dbregs, proc_write_dbregs
  92  *      deal with the processor debug register set, otherwise as above.
  93  *
  94  * proc_sstep(proc)
  95  *      Arrange for the process to trap after executing a single instruction.
  96  */
  97
  98 #define PROC_ACTION(action) do {                                        \
  99         int error;                                                      \
 100                                                                         \
 101         PROC_LOCK_ASSERT(td->td_proc, MA_OWNED);                        \
 102         if ((td->td_proc->p_flag & P_INMEM) == 0)                       \
 103                 error = EIO;                                            \
 104         else                                                            \
 105                 error = (action);                                       \
 106         return (error);                                                 \
 107 } while(0)
 108
 109 int
 110 proc_read_regs(struct thread *td, struct reg *regs)
 111 {
 112
 113         PROC_ACTION(fill_regs(td, regs));
 114 }
 115
 116 int
 117 proc_write_regs(struct thread *td, struct reg *regs)
 118 {
 119
 120         PROC_ACTION(set_regs(td, regs));
 121 }
 122
 123 int
 124 proc_read_dbregs(struct thread *td, struct dbreg *dbregs)
 125 {
 126
 127         PROC_ACTION(fill_dbregs(td, dbregs));
 128 }
 129
 130 int
 131 proc_write_dbregs(struct thread *td, struct dbreg *dbregs)
 132 {
 133
 134         PROC_ACTION(set_dbregs(td, dbregs));
 135 }
 136
 137 /*
 138  * Ptrace doesn't support fpregs at all, and there are no security holes
 139  * or translations for fpregs, so we can just copy them.
 140  */
 141 int
 142 proc_read_fpregs(struct thread *td, struct fpreg *fpregs)
 143 {
 144
 145         PROC_ACTION(fill_fpregs(td, fpregs));
 146 }
 147
 148 int
 149 proc_write_fpregs(struct thread *td, struct fpreg *fpregs)
 150 {
 151
 152         PROC_ACTION(set_fpregs(td, fpregs));
 153 }
 154
 155 #ifdef COMPAT_FREEBSD32
 156 /* For 32 bit binaries, we need to expose the 32 bit regs layouts. */
 157 int
 158 proc_read_regs32(struct thread *td, struct reg32 *regs32)
 159 {
 160
 161         PROC_ACTION(fill_regs32(td, regs32));
 162 }
 163
 164 int
 165 proc_write_regs32(struct thread *td, struct reg32 *regs32)
 166 {
 167
 168         PROC_ACTION(set_regs32(td, regs32));
 169 }
 170
 171 int
 172 proc_read_dbregs32(struct thread *td, struct dbreg32 *dbregs32)
 173 {
 174
 175         PROC_ACTION(fill_dbregs32(td, dbregs32));
 176 }
 177
 178 int
 179 proc_write_dbregs32(struct thread *td, struct dbreg32 *dbregs32)
 180 {
 181
 182         PROC_ACTION(set_dbregs32(td, dbregs32));
 183 }
 184
 185 int
 186 proc_read_fpregs32(struct thread *td, struct fpreg32 *fpregs32)
 187 {
 188
 189         PROC_ACTION(fill_fpregs32(td, fpregs32));
 190 }
 191
 192 int
 193 proc_write_fpregs32(struct thread *td, struct fpreg32 *fpregs32)
 194 {
 195
 196         PROC_ACTION(set_fpregs32(td, fpregs32));
 197 }
 198 #endif
 199
 200 int
 201 proc_sstep(struct thread *td)
 202 {
 203
 204         PROC_ACTION(ptrace_single_step(td));
 205 }
 206
 207 int
 208 proc_rwmem(struct proc *p, struct uio *uio)
 209 {
 210         vm_map_t map;
 211         vm_offset_t pageno;             /* page number */
 212         vm_prot_t reqprot;
 213         int error, fault_flags, page_offset, writing;
 214
 215         /*
 216          * Assert that someone has locked this vmspace.  (Should be
 217          * curthread but we can't assert that.)  This keeps the process
 218          * from exiting out from under us until this operation completes.
 219          */
 220         PROC_ASSERT_HELD(p);
 221         PROC_LOCK_ASSERT(p, MA_NOTOWNED);
 222
 223         /*
 224          * The map we want...
 225          */
 226         map = &p->p_vmspace->vm_map;
 227
 228         /*
 229          * If we are writing, then we request vm_fault() to create a private
 230          * copy of each page.  Since these copies will not be writeable by the
 231          * process, we must explicity request that they be dirtied.
 232          */
 233         writing = uio->uio_rw == UIO_WRITE;
 234         reqprot = writing ? VM_PROT_COPY | VM_PROT_READ : VM_PROT_READ;
 235         fault_flags = writing ? VM_FAULT_DIRTY : VM_FAULT_NORMAL;
 236
 237         /*
 238          * Only map in one page at a time.  We don't have to, but it
 239          * makes things easier.  This way is trivial - right?
 240          */
 241         do {
 242                 vm_offset_t uva;
 243                 u_int len;
 244                 vm_page_t m;
 245
 246                 uva = (vm_offset_t)uio->uio_offset;
 247
 248                 /*
 249                  * Get the page number of this segment.
 250                  */
 251                 pageno = trunc_page(uva);
 252                 page_offset = uva - pageno;
 253
 254                 /*
 255                  * How many bytes to copy
 256                  */
 257                 len = min(PAGE_SIZE - page_offset, uio->uio_resid);
 258
 259                 /*
 260                  * Fault and hold the page on behalf of the process.
 261                  */
 262                 error = vm_fault(map, pageno, reqprot, fault_flags, &m);
 263                 if (error != KERN_SUCCESS) {
 264                         if (error == KERN_RESOURCE_SHORTAGE)
 265                                 error = ENOMEM;
 266                         else
 267                                 error = EFAULT;
 268                         break;
 269                 }
 270
 271                 /*
 272                  * Now do the i/o move.
 273                  */
 274                 error = uiomove_fromphys(&m, page_offset, len, uio);
 275
 276                 /* Make the I-cache coherent for breakpoints. */
 277                 if (writing && error == 0) {
 278                         vm_map_lock_read(map);
 279                         if (vm_map_check_protection(map, pageno, pageno +
 280                             PAGE_SIZE, VM_PROT_EXECUTE))
 281                                 vm_sync_icache(map, uva, len);
 282                         vm_map_unlock_read(map);
 283                 }
 284
 285                 /*
 286                  * Release the page.
 287                  */
 288                 vm_page_unwire(m, PQ_ACTIVE);
 289
 290         } while (error == 0 && uio->uio_resid > 0);
 291
 292         return (error);
 293 }
 294
 295 static ssize_t
 296 proc_iop(struct thread *td, struct proc *p, vm_offset_t va, void *buf,
 297     size_t len, enum uio_rw rw)
 298 {
 299         struct iovec iov;
 300         struct uio uio;
 301         ssize_t slen;
 302
 303         MPASS(len < SSIZE_MAX);
 304         slen = (ssize_t)len;
 305
 306         iov.iov_base = (caddr_t)buf;
 307         iov.iov_len = len;
 308         uio.uio_iov = &iov;
 309         uio.uio_iovcnt = 1;
 310         uio.uio_offset = va;
 311         uio.uio_resid = slen;
 312         uio.uio_segflg = UIO_SYSSPACE;
 313         uio.uio_rw = rw;
 314         uio.uio_td = td;
 315         proc_rwmem(p, &uio);
 316         if (uio.uio_resid == slen)
 317                 return (-1);
 318         return (slen - uio.uio_resid);
 319 }
 320
 321 ssize_t
 322 proc_readmem(struct thread *td, struct proc *p, vm_offset_t va, void *buf,
 323     size_t len)
 324 {
 325
 326         return (proc_iop(td, p, va, buf, len, UIO_READ));
 327 }
 328
 329 ssize_t
 330 proc_writemem(struct thread *td, struct proc *p, vm_offset_t va, void *buf,
 331     size_t len)
 332 {
 333
 334         return (proc_iop(td, p, va, buf, len, UIO_WRITE));
 335 }
 336
 337 static int
 338 ptrace_vm_entry(struct thread *td, struct proc *p, struct ptrace_vm_entry *pve)
 339 {
 340         struct vattr vattr;
 341         vm_map_t map;
 342         vm_map_entry_t entry;
 343         vm_object_t obj, tobj, lobj;
 344         struct vmspace *vm;
 345         struct vnode *vp;
 346         char *freepath, *fullpath;
 347         u_int pathlen;
 348         int error, index;
 349
 350         error = 0;
 351         obj = NULL;
 352
 353         vm = vmspace_acquire_ref(p);
 354         map = &vm->vm_map;
 355         vm_map_lock_read(map);
 356
 357         do {
 358                 KASSERT((map->header.eflags & MAP_ENTRY_IS_SUB_MAP) == 0,
 359                     ("Submap in map header"));
 360                 index = 0;
 361                 VM_MAP_ENTRY_FOREACH(entry, map) {
 362                         if (index >= pve->pve_entry &&
 363                             (entry->eflags & MAP_ENTRY_IS_SUB_MAP) == 0)
 364                                 break;
 365                         index++;
 366                 }
 367                 if (index < pve->pve_entry) {
 368                         error = EINVAL;
 369                         break;
 370                 }
 371                 if (entry == &map->header) {
 372                         error = ENOENT;
 373                         break;
 374                 }
 375
 376                 /* We got an entry. */
 377                 pve->pve_entry = index + 1;
 378                 pve->pve_timestamp = map->timestamp;
 379                 pve->pve_start = entry->start;
 380                 pve->pve_end = entry->end - 1;
 381                 pve->pve_offset = entry->offset;
 382                 pve->pve_prot = entry->protection;
 383
 384                 /* Backing object's path needed? */
 385                 if (pve->pve_pathlen == 0)
 386                         break;
 387
 388                 pathlen = pve->pve_pathlen;
 389                 pve->pve_pathlen = 0;
 390
 391                 obj = entry->object.vm_object;
 392                 if (obj != NULL)
 393                         VM_OBJECT_RLOCK(obj);
 394         } while (0);
 395
 396         vm_map_unlock_read(map);
 397
 398         pve->pve_fsid = VNOVAL;
 399         pve->pve_fileid = VNOVAL;
 400
 401         if (error == 0 && obj != NULL) {
 402                 lobj = obj;
 403                 for (tobj = obj; tobj != NULL; tobj = tobj->backing_object) {
 404                         if (tobj != obj)
 405                                 VM_OBJECT_RLOCK(tobj);
 406                         if (lobj != obj)
 407                                 VM_OBJECT_RUNLOCK(lobj);
 408                         lobj = tobj;
 409                         pve->pve_offset += tobj->backing_object_offset;
 410                 }
 411                 vp = vm_object_vnode(lobj);
 412                 if (vp != NULL)
 413                         vref(vp);
 414                 if (lobj != obj)
 415                         VM_OBJECT_RUNLOCK(lobj);
 416                 VM_OBJECT_RUNLOCK(obj);
 417
 418                 if (vp != NULL) {
 419                         freepath = NULL;
 420                         fullpath = NULL;
 421                         vn_fullpath(vp, &fullpath, &freepath);
 422                         vn_lock(vp, LK_SHARED | LK_RETRY);
 423                         if (VOP_GETATTR(vp, &vattr, td->td_ucred) == 0) {
 424                                 pve->pve_fileid = vattr.va_fileid;
 425                                 pve->pve_fsid = vattr.va_fsid;
 426                         }
 427                         vput(vp);
 428
 429                         if (fullpath != NULL) {
 430                                 pve->pve_pathlen = strlen(fullpath) + 1;
 431                                 if (pve->pve_pathlen <= pathlen) {
 432                                         error = copyout(fullpath, pve->pve_path,
 433                                             pve->pve_pathlen);
 434                                 } else
 435                                         error = ENAMETOOLONG;
 436                         }
 437                         if (freepath != NULL)
 438                                 free(freepath, M_TEMP);
 439                 }
 440         }
 441         vmspace_free(vm);
 442         if (error == 0)
 443                 CTR3(KTR_PTRACE, "PT_VM_ENTRY: pid %d, entry %d, start %p",
 444                     p->p_pid, pve->pve_entry, pve->pve_start);
 445
 446         return (error);
 447 }
 448
 449 /*
 450  * Process debugging system call.
 451  */
 452 #ifndef _SYS_SYSPROTO_H_
 453 struct ptrace_args {
 454         int     req;
 455         pid_t   pid;
 456         caddr_t addr;
 457         int     data;
 458 };
 459 #endif
 460
 461 int
 462 sys_ptrace(struct thread *td, struct ptrace_args *uap)
 463 {
 464         /*
 465          * XXX this obfuscation is to reduce stack usage, but the register
 466          * structs may be too large to put on the stack anyway.
 467          */
 468         union {
 469                 struct ptrace_io_desc piod;
 470                 struct ptrace_lwpinfo pl;
 471                 struct ptrace_vm_entry pve;
 472                 struct dbreg dbreg;
 473                 struct fpreg fpreg;
 474                 struct reg reg;
 475                 char args[sizeof(td->td_sa.args)];
 476                 struct ptrace_sc_ret psr;
 477                 int ptevents;
 478         } r;
 479         void *addr;
 480         int error = 0;
 481
 482         AUDIT_ARG_PID(uap->pid);
 483         AUDIT_ARG_CMD(uap->req);
 484         AUDIT_ARG_VALUE(uap->data);
 485         addr = &r;
 486         switch (uap->req) {
 487         case PT_GET_EVENT_MASK:
 488         case PT_LWPINFO:
 489         case PT_GET_SC_ARGS:
 490         case PT_GET_SC_RET:
 491                 break;
 492         case PT_GETREGS:
 493                 bzero(&r.reg, sizeof(r.reg));
 494                 break;
 495         case PT_GETFPREGS:
 496                 bzero(&r.fpreg, sizeof(r.fpreg));
 497                 break;
 498         case PT_GETDBREGS:
 499                 bzero(&r.dbreg, sizeof(r.dbreg));
 500                 break;
 501         case PT_SETREGS:
 502                 error = copyin(uap->addr, &r.reg, sizeof(r.reg));
 503                 break;
 504         case PT_SETFPREGS:
 505                 error = copyin(uap->addr, &r.fpreg, sizeof(r.fpreg));
 506                 break;
 507         case PT_SETDBREGS:
 508                 error = copyin(uap->addr, &r.dbreg, sizeof(r.dbreg));
 509                 break;
 510         case PT_SET_EVENT_MASK:
 511                 if (uap->data != sizeof(r.ptevents))
 512                         error = EINVAL;
 513                 else
 514                         error = copyin(uap->addr, &r.ptevents, uap->data);
 515                 break;
 516         case PT_IO:
 517                 error = copyin(uap->addr, &r.piod, sizeof(r.piod));
 518                 break;
 519         case PT_VM_ENTRY:
 520                 error = copyin(uap->addr, &r.pve, sizeof(r.pve));
 521                 break;
 522         default:
 523                 addr = uap->addr;
 524                 break;
 525         }
 526         if (error)
 527                 return (error);
 528
 529         error = kern_ptrace(td, uap->req, uap->pid, addr, uap->data);
 530         if (error)
 531                 return (error);
 532
 533         switch (uap->req) {
 534         case PT_VM_ENTRY:
 535                 error = copyout(&r.pve, uap->addr, sizeof(r.pve));
 536                 break;
 537         case PT_IO:
 538                 error = copyout(&r.piod, uap->addr, sizeof(r.piod));
 539                 break;
 540         case PT_GETREGS:
 541                 error = copyout(&r.reg, uap->addr, sizeof(r.reg));
 542                 break;
 543         case PT_GETFPREGS:
 544                 error = copyout(&r.fpreg, uap->addr, sizeof(r.fpreg));
 545                 break;
 546         case PT_GETDBREGS:
 547                 error = copyout(&r.dbreg, uap->addr, sizeof(r.dbreg));
 548                 break;
 549         case PT_GET_EVENT_MASK:
 550                 /* NB: The size in uap->data is validated in kern_ptrace(). */
 551                 error = copyout(&r.ptevents, uap->addr, uap->data);
 552                 break;
 553         case PT_LWPINFO:
 554                 /* NB: The size in uap->data is validated in kern_ptrace(). */
 555                 error = copyout(&r.pl, uap->addr, uap->data);
 556                 break;
 557         case PT_GET_SC_ARGS:
 558                 error = copyout(r.args, uap->addr, MIN(uap->data,
 559                     sizeof(r.args)));
 560                 break;
 561         case PT_GET_SC_RET:
 562                 error = copyout(&r.psr, uap->addr, MIN(uap->data,
 563                     sizeof(r.psr)));
 564                 break;
 565         }
 566
 567         return (error);
 568 }
 569
 570 #ifdef COMPAT_FREEBSD32
 571 /*
 572  *   PROC_READ(regs, td2, addr);
 573  * becomes either:
 574  *   proc_read_regs(td2, addr);
 575  * or
 576  *   proc_read_regs32(td2, addr);
 577  * .. except this is done at runtime.  There is an additional
 578  * complication in that PROC_WRITE disallows 32 bit consumers
 579  * from writing to 64 bit address space targets.
 580  */
 581 #define PROC_READ(w, t, a)      wrap32 ? \
 582         proc_read_ ## w ## 32(t, a) : \
 583         proc_read_ ## w (t, a)
 584 #define PROC_WRITE(w, t, a)     wrap32 ? \
 585         (safe ? proc_write_ ## w ## 32(t, a) : EINVAL ) : \
 586         proc_write_ ## w (t, a)
 587 #else
 588 #define PROC_READ(w, t, a)      proc_read_ ## w (t, a)
 589 #define PROC_WRITE(w, t, a)     proc_write_ ## w (t, a)
 590 #endif
 591
 592 void
 593 proc_set_traced(struct proc *p, bool stop)
 594 {
 595
 596         sx_assert(&proctree_lock, SX_XLOCKED);
 597         PROC_LOCK_ASSERT(p, MA_OWNED);
 598         p->p_flag |= P_TRACED;
 599         if (stop)
 600                 p->p_flag2 |= P2_PTRACE_FSTP;
 601         p->p_ptevents = PTRACE_DEFAULT;
 602 }
 603
 604 int
 605 kern_ptrace(struct thread *td, int req, pid_t pid, void *addr, int data)
 606 {
 607         struct iovec iov;
 608         struct uio uio;
 609         struct proc *curp, *p, *pp;
 610         struct thread *td2 = NULL, *td3;
 611         struct ptrace_io_desc *piod = NULL;
 612         struct ptrace_lwpinfo *pl;
 613         struct ptrace_sc_ret *psr;
 614         int error, num, tmp;
 615         int proctree_locked = 0;
 616         lwpid_t tid = 0, *buf;
 617 #ifdef COMPAT_FREEBSD32
 618         int wrap32 = 0, safe = 0;
 619 #endif
 620
 621         curp = td->td_proc;
 622
 623         /* Lock proctree before locking the process. */
 624         switch (req) {
 625         case PT_TRACE_ME:
 626         case PT_ATTACH:
 627         case PT_STEP:
 628         case PT_CONTINUE:
 629         case PT_TO_SCE:
 630         case PT_TO_SCX:
 631         case PT_SYSCALL:
 632         case PT_FOLLOW_FORK:
 633         case PT_LWP_EVENTS:
 634         case PT_GET_EVENT_MASK:
 635         case PT_SET_EVENT_MASK:
 636         case PT_DETACH:
 637         case PT_GET_SC_ARGS:
 638                 sx_xlock(&proctree_lock);
 639                 proctree_locked = 1;
 640                 break;
 641         default:
 642                 break;
 643         }
 644
 645         if (req == PT_TRACE_ME) {
 646                 p = td->td_proc;
 647                 PROC_LOCK(p);
 648         } else {
 649                 if (pid <= PID_MAX) {
 650                         if ((p = pfind(pid)) == NULL) {
 651                                 if (proctree_locked)
 652                                         sx_xunlock(&proctree_lock);
 653                                 return (ESRCH);
 654                         }
 655                 } else {
 656                         td2 = tdfind(pid, -1);
 657                         if (td2 == NULL) {
 658                                 if (proctree_locked)
 659                                         sx_xunlock(&proctree_lock);
 660                                 return (ESRCH);
 661                         }
 662                         p = td2->td_proc;
 663                         tid = pid;
 664                         pid = p->p_pid;
 665                 }
 666         }
 667         AUDIT_ARG_PROCESS(p);
 668
 669         if ((p->p_flag & P_WEXIT) != 0) {
 670                 error = ESRCH;
 671                 goto fail;
 672         }
 673         if ((error = p_cansee(td, p)) != 0)
 674                 goto fail;
 675
 676         if ((error = p_candebug(td, p)) != 0)
 677                 goto fail;
 678
 679         /*
 680          * System processes can't be debugged.
 681          */
 682         if ((p->p_flag & P_SYSTEM) != 0) {
 683                 error = EINVAL;
 684                 goto fail;
 685         }
 686
 687         if (tid == 0) {
 688                 if ((p->p_flag & P_STOPPED_TRACE) != 0) {
 689                         KASSERT(p->p_xthread != NULL, ("NULL p_xthread"));
 690                         td2 = p->p_xthread;
 691                 } else {
 692                         td2 = FIRST_THREAD_IN_PROC(p);
 693                 }
 694                 tid = td2->td_tid;
 695         }
 696
 697 #ifdef COMPAT_FREEBSD32
 698         /*
 699          * Test if we're a 32 bit client and what the target is.
 700          * Set the wrap controls accordingly.
 701          */
 702         if (SV_CURPROC_FLAG(SV_ILP32)) {
 703                 if (SV_PROC_FLAG(td2->td_proc, SV_ILP32))
 704                         safe = 1;
 705                 wrap32 = 1;
 706         }
 707 #endif
 708         /*
 709          * Permissions check
 710          */
 711         switch (req) {
 712         case PT_TRACE_ME:
 713                 /*
 714                  * Always legal, when there is a parent process which
 715                  * could trace us.  Otherwise, reject.
 716                  */
 717                 if ((p->p_flag & P_TRACED) != 0) {
 718                         error = EBUSY;
 719                         goto fail;
 720                 }
 721                 if (p->p_pptr == initproc) {
 722                         error = EPERM;
 723                         goto fail;
 724                 }
 725                 break;
 726
 727         case PT_ATTACH:
 728                 /* Self */
 729                 if (p == td->td_proc) {
 730                         error = EINVAL;
 731                         goto fail;
 732                 }
 733
 734                 /* Already traced */
 735                 if (p->p_flag & P_TRACED) {
 736                         error = EBUSY;
 737                         goto fail;
 738                 }
 739
 740                 /* Can't trace an ancestor if you're being traced. */
 741                 if (curp->p_flag & P_TRACED) {
 742                         for (pp = curp->p_pptr; pp != NULL; pp = pp->p_pptr) {
 743                                 if (pp == p) {
 744                                         error = EINVAL;
 745                                         goto fail;
 746                                 }
 747                         }
 748                 }
 749
 750                 /* OK */
 751                 break;
 752
 753         case PT_CLEARSTEP:
 754                 /* Allow thread to clear single step for itself */
 755                 if (td->td_tid == tid)
 756                         break;
 757
 758                 /* FALLTHROUGH */
 759         default:
 760                 /* not being traced... */
 761                 if ((p->p_flag & P_TRACED) == 0) {
 762                         error = EPERM;
 763                         goto fail;
 764                 }
 765
 766                 /* not being traced by YOU */
 767                 if (p->p_pptr != td->td_proc) {
 768                         error = EBUSY;
 769                         goto fail;
 770                 }
 771
 772                 /* not currently stopped */
 773                 if ((p->p_flag & P_STOPPED_TRACE) == 0 ||
 774                     p->p_suspcount != p->p_numthreads  ||
 775                     (p->p_flag & P_WAITED) == 0) {
 776                         error = EBUSY;
 777                         goto fail;
 778                 }
 779
 780                 /* OK */
 781                 break;
 782         }
 783
 784         /* Keep this process around until we finish this request. */
 785         _PHOLD(p);
 786
 787 #ifdef FIX_SSTEP
 788         /*
 789          * Single step fixup ala procfs
 790          */
 791         FIX_SSTEP(td2);
 792 #endif
 793
 794         /*
 795          * Actually do the requests
 796          */
 797
 798         td->td_retval[0] = 0;
 799
 800         switch (req) {
 801         case PT_TRACE_ME:
 802                 /* set my trace flag and "owner" so it can read/write me */
 803                 proc_set_traced(p, false);
 804                 if (p->p_flag & P_PPWAIT)
 805                         p->p_flag |= P_PPTRACE;
 806                 CTR1(KTR_PTRACE, "PT_TRACE_ME: pid %d", p->p_pid);
 807                 break;
 808
 809         case PT_ATTACH:
 810                 /* security check done above */
 811                 /*
 812                  * It would be nice if the tracing relationship was separate
 813                  * from the parent relationship but that would require
 814                  * another set of links in the proc struct or for "wait"
 815                  * to scan the entire proc table.  To make life easier,
 816                  * we just re-parent the process we're trying to trace.
 817                  * The old parent is remembered so we can put things back
 818                  * on a "detach".
 819                  */
 820                 proc_set_traced(p, true);
 821                 proc_reparent(p, td->td_proc, false);
 822                 CTR2(KTR_PTRACE, "PT_ATTACH: pid %d, oppid %d", p->p_pid,
 823                     p->p_oppid);
 824
 825                 sx_xunlock(&proctree_lock);
 826                 proctree_locked = 0;
 827                 MPASS(p->p_xthread == NULL);
 828                 MPASS((p->p_flag & P_STOPPED_TRACE) == 0);
 829
 830                 /*
 831                  * If already stopped due to a stop signal, clear the
 832                  * existing stop before triggering a traced SIGSTOP.
 833                  */
 834                 if ((p->p_flag & P_STOPPED_SIG) != 0) {
 835                         PROC_SLOCK(p);
 836                         p->p_flag &= ~(P_STOPPED_SIG | P_WAITED);
 837                         thread_unsuspend(p);
 838                         PROC_SUNLOCK(p);
 839                 }
 840
 841                 kern_psignal(p, SIGSTOP);
 842                 break;
 843
 844         case PT_CLEARSTEP:
 845                 CTR2(KTR_PTRACE, "PT_CLEARSTEP: tid %d (pid %d)", td2->td_tid,
 846                     p->p_pid);
 847                 error = ptrace_clear_single_step(td2);
 848                 break;
 849
 850         case PT_SETSTEP:
 851                 CTR2(KTR_PTRACE, "PT_SETSTEP: tid %d (pid %d)", td2->td_tid,
 852                     p->p_pid);
 853                 error = ptrace_single_step(td2);
 854                 break;
 855
 856         case PT_SUSPEND:
 857                 CTR2(KTR_PTRACE, "PT_SUSPEND: tid %d (pid %d)", td2->td_tid,
 858                     p->p_pid);
 859                 td2->td_dbgflags |= TDB_SUSPEND;
 860                 thread_lock(td2);
 861                 td2->td_flags |= TDF_NEEDSUSPCHK;
 862                 thread_unlock(td2);
 863                 break;
 864
 865         case PT_RESUME:
 866                 CTR2(KTR_PTRACE, "PT_RESUME: tid %d (pid %d)", td2->td_tid,
 867                     p->p_pid);
 868                 td2->td_dbgflags &= ~TDB_SUSPEND;
 869                 break;
 870
 871         case PT_FOLLOW_FORK:
 872                 CTR3(KTR_PTRACE, "PT_FOLLOW_FORK: pid %d %s -> %s", p->p_pid,
 873                     p->p_ptevents & PTRACE_FORK ? "enabled" : "disabled",
 874                     data ? "enabled" : "disabled");
 875                 if (data)
 876                         p->p_ptevents |= PTRACE_FORK;
 877                 else
 878                         p->p_ptevents &= ~PTRACE_FORK;
 879                 break;
 880
 881         case PT_LWP_EVENTS:
 882                 CTR3(KTR_PTRACE, "PT_LWP_EVENTS: pid %d %s -> %s", p->p_pid,
 883                     p->p_ptevents & PTRACE_LWP ? "enabled" : "disabled",
 884                     data ? "enabled" : "disabled");
 885                 if (data)
 886                         p->p_ptevents |= PTRACE_LWP;
 887                 else
 888                         p->p_ptevents &= ~PTRACE_LWP;
 889                 break;
 890
 891         case PT_GET_EVENT_MASK:
 892                 if (data != sizeof(p->p_ptevents)) {
 893                         error = EINVAL;
 894                         break;
 895                 }
 896                 CTR2(KTR_PTRACE, "PT_GET_EVENT_MASK: pid %d mask %#x", p->p_pid,
 897                     p->p_ptevents);
 898                 *(int *)addr = p->p_ptevents;
 899                 break;
 900
 901         case PT_SET_EVENT_MASK:
 902                 if (data != sizeof(p->p_ptevents)) {
 903                         error = EINVAL;
 904                         break;
 905                 }
 906                 tmp = *(int *)addr;
 907                 if ((tmp & ~(PTRACE_EXEC | PTRACE_SCE | PTRACE_SCX |
 908                     PTRACE_FORK | PTRACE_LWP | PTRACE_VFORK)) != 0) {
 909                         error = EINVAL;
 910                         break;
 911                 }
 912                 CTR3(KTR_PTRACE, "PT_SET_EVENT_MASK: pid %d mask %#x -> %#x",
 913                     p->p_pid, p->p_ptevents, tmp);
 914                 p->p_ptevents = tmp;
 915                 break;
 916
 917         case PT_GET_SC_ARGS:
 918                 CTR1(KTR_PTRACE, "PT_GET_SC_ARGS: pid %d", p->p_pid);
 919                 if ((td2->td_dbgflags & (TDB_SCE | TDB_SCX)) == 0
 920 #ifdef COMPAT_FREEBSD32
 921                     || (wrap32 && !safe)
 922 #endif
 923                     ) {
 924                         error = EINVAL;
 925                         break;
 926                 }
 927                 bzero(addr, sizeof(td2->td_sa.args));
 928                 bcopy(td2->td_sa.args, addr, td2->td_sa.callp->sy_narg *
 929                     sizeof(register_t));
 930                 break;
 931
 932         case PT_GET_SC_RET:
 933                 if ((td2->td_dbgflags & (TDB_SCX)) == 0
 934 #ifdef COMPAT_FREEBSD32
 935                     || (wrap32 && !safe)
 936 #endif
 937                     ) {
 938                         error = EINVAL;
 939                         break;
 940                 }
 941                 psr = addr;
 942                 bzero(psr, sizeof(*psr));
 943                 psr->sr_error = td2->td_errno;
 944                 if (psr->sr_error == 0) {
 945                         psr->sr_retval[0] = td2->td_retval[0];
 946                         psr->sr_retval[1] = td2->td_retval[1];
 947                 }
 948                 CTR4(KTR_PTRACE,
 949                     "PT_GET_SC_RET: pid %d error %d retval %#lx,%#lx",
 950                     p->p_pid, psr->sr_error, psr->sr_retval[0],
 951                     psr->sr_retval[1]);
 952                 break;
 953
 954         case PT_STEP:
 955         case PT_CONTINUE:
 956         case PT_TO_SCE:
 957         case PT_TO_SCX:
 958         case PT_SYSCALL:
 959         case PT_DETACH:
 960                 /* Zero means do not send any signal */
 961                 if (data < 0 || data > _SIG_MAXSIG) {
 962                         error = EINVAL;
 963                         break;
 964                 }
 965
 966                 switch (req) {
 967                 case PT_STEP:
 968                         CTR3(KTR_PTRACE, "PT_STEP: tid %d (pid %d), sig = %d",
 969                             td2->td_tid, p->p_pid, data);
 970                         error = ptrace_single_step(td2);
 971                         if (error)
 972                                 goto out;
 973                         break;
 974                 case PT_CONTINUE:
 975                 case PT_TO_SCE:
 976                 case PT_TO_SCX:
 977                 case PT_SYSCALL:
 978                         if (addr != (void *)1) {
 979                                 error = ptrace_set_pc(td2,
 980                                     (u_long)(uintfptr_t)addr);
 981                                 if (error)
 982                                         goto out;
 983                         }
 984                         switch (req) {
 985                         case PT_TO_SCE:
 986                                 p->p_ptevents |= PTRACE_SCE;
 987                                 CTR4(KTR_PTRACE,
 988                     "PT_TO_SCE: pid %d, events = %#x, PC = %#lx, sig = %d",
 989                                     p->p_pid, p->p_ptevents,
 990                                     (u_long)(uintfptr_t)addr, data);
 991                                 break;
 992                         case PT_TO_SCX:
 993                                 p->p_ptevents |= PTRACE_SCX;
 994                                 CTR4(KTR_PTRACE,
 995                     "PT_TO_SCX: pid %d, events = %#x, PC = %#lx, sig = %d",
 996                                     p->p_pid, p->p_ptevents,
 997                                     (u_long)(uintfptr_t)addr, data);
 998                                 break;
 999                         case PT_SYSCALL:
1000                                 p->p_ptevents |= PTRACE_SYSCALL;
1001                                 CTR4(KTR_PTRACE,
1002                     "PT_SYSCALL: pid %d, events = %#x, PC = %#lx, sig = %d",
1003                                     p->p_pid, p->p_ptevents,
1004                                     (u_long)(uintfptr_t)addr, data);
1005                                 break;
1006                         case PT_CONTINUE:
1007                                 CTR3(KTR_PTRACE,
1008                                     "PT_CONTINUE: pid %d, PC = %#lx, sig = %d",
1009                                     p->p_pid, (u_long)(uintfptr_t)addr, data);
1010                                 break;
1011                         }
1012                         break;
1013                 case PT_DETACH:
1014                         /*
1015                          * Reset the process parent.
1016                          *
1017                          * NB: This clears P_TRACED before reparenting
1018                          * a detached process back to its original
1019                          * parent.  Otherwise the debugee will be set
1020                          * as an orphan of the debugger.
1021                          */
1022                         p->p_flag &= ~(P_TRACED | P_WAITED);
1023                         if (p->p_oppid != p->p_pptr->p_pid) {
1024                                 PROC_LOCK(p->p_pptr);
1025                                 sigqueue_take(p->p_ksi);
1026                                 PROC_UNLOCK(p->p_pptr);
1027
1028                                 pp = proc_realparent(p);
1029                                 proc_reparent(p, pp, false);
1030                                 if (pp == initproc)
1031                                         p->p_sigparent = SIGCHLD;
1032                                 CTR3(KTR_PTRACE,
1033                             "PT_DETACH: pid %d reparented to pid %d, sig %d",
1034                                     p->p_pid, pp->p_pid, data);
1035                         } else
1036                                 CTR2(KTR_PTRACE, "PT_DETACH: pid %d, sig %d",
1037                                     p->p_pid, data);
1038                         p->p_ptevents = 0;
1039                         FOREACH_THREAD_IN_PROC(p, td3) {
1040                                 if ((td3->td_dbgflags & TDB_FSTP) != 0) {
1041                                         sigqueue_delete(&td3->td_sigqueue,
1042                                             SIGSTOP);
1043                                 }
1044                                 td3->td_dbgflags &= ~(TDB_XSIG | TDB_FSTP |
1045                                     TDB_SUSPEND);
1046                         }
1047
1048                         if ((p->p_flag2 & P2_PTRACE_FSTP) != 0) {
1049                                 sigqueue_delete(&p->p_sigqueue, SIGSTOP);
1050                                 p->p_flag2 &= ~P2_PTRACE_FSTP;
1051                         }
1052
1053                         /* should we send SIGCHLD? */
1054                         /* childproc_continued(p); */
1055                         break;
1056                 }
1057
1058                 sx_xunlock(&proctree_lock);
1059                 proctree_locked = 0;
1060
1061         sendsig:
1062                 MPASS(proctree_locked == 0);
1063
1064                 /*
1065                  * Clear the pending event for the thread that just
1066                  * reported its event (p_xthread).  This may not be
1067                  * the thread passed to PT_CONTINUE, PT_STEP, etc. if
1068                  * the debugger is resuming a different thread.
1069                  *
1070                  * Deliver any pending signal via the reporting thread.
1071                  */
1072                 MPASS(p->p_xthread != NULL);
1073                 p->p_xthread->td_dbgflags &= ~TDB_XSIG;
1074                 p->p_xthread->td_xsig = data;
1075                 p->p_xthread = NULL;
1076                 p->p_xsig = data;
1077
1078                 /*
1079                  * P_WKILLED is insurance that a PT_KILL/SIGKILL
1080                  * always works immediately, even if another thread is
1081                  * unsuspended first and attempts to handle a
1082                  * different signal or if the POSIX.1b style signal
1083                  * queue cannot accommodate any new signals.
1084                  */
1085                 if (data == SIGKILL)
1086                         proc_wkilled(p);
1087
1088                 /*
1089                  * Unsuspend all threads.  To leave a thread
1090                  * suspended, use PT_SUSPEND to suspend it before
1091                  * continuing the process.
1092                  */
1093                 PROC_SLOCK(p);
1094                 p->p_flag &= ~(P_STOPPED_TRACE | P_STOPPED_SIG | P_WAITED);
1095                 thread_unsuspend(p);
1096                 PROC_SUNLOCK(p);
1097                 break;
1098
1099         case PT_WRITE_I:
1100         case PT_WRITE_D:
1101                 td2->td_dbgflags |= TDB_USERWR;
1102                 PROC_UNLOCK(p);
1103                 error = 0;
1104                 if (proc_writemem(td, p, (off_t)(uintptr_t)addr, &data,
1105                     sizeof(int)) != sizeof(int))
1106                         error = ENOMEM;
1107                 else
1108                         CTR3(KTR_PTRACE, "PT_WRITE: pid %d: %p <= %#x",
1109                             p->p_pid, addr, data);
1110                 PROC_LOCK(p);
1111                 break;
1112
1113         case PT_READ_I:
1114         case PT_READ_D:
1115                 PROC_UNLOCK(p);
1116                 error = tmp = 0;
1117                 if (proc_readmem(td, p, (off_t)(uintptr_t)addr, &tmp,
1118                     sizeof(int)) != sizeof(int))
1119                         error = ENOMEM;
1120                 else
1121                         CTR3(KTR_PTRACE, "PT_READ: pid %d: %p >= %#x",
1122                             p->p_pid, addr, tmp);
1123                 td->td_retval[0] = tmp;
1124                 PROC_LOCK(p);
1125                 break;
1126
1127         case PT_IO:
1128                 piod = addr;
1129                 iov.iov_base = piod->piod_addr;
1130                 iov.iov_len = piod->piod_len;
1131                 uio.uio_offset = (off_t)(uintptr_t)piod->piod_offs;
1132                 uio.uio_resid = piod->piod_len;
1133                 uio.uio_iov = &iov;
1134                 uio.uio_iovcnt = 1;
1135                 uio.uio_segflg = UIO_USERSPACE;
1136                 uio.uio_td = td;
1137                 switch (piod->piod_op) {
1138                 case PIOD_READ_D:
1139                 case PIOD_READ_I:
1140                         CTR3(KTR_PTRACE, "PT_IO: pid %d: READ (%p, %#x)",
1141                             p->p_pid, (uintptr_t)uio.uio_offset, uio.uio_resid);
1142                         uio.uio_rw = UIO_READ;
1143                         break;
1144                 case PIOD_WRITE_D:
1145                 case PIOD_WRITE_I:
1146                         CTR3(KTR_PTRACE, "PT_IO: pid %d: WRITE (%p, %#x)",
1147                             p->p_pid, (uintptr_t)uio.uio_offset, uio.uio_resid);
1148                         td2->td_dbgflags |= TDB_USERWR;
1149                         uio.uio_rw = UIO_WRITE;
1150                         break;
1151                 default:
1152                         error = EINVAL;
1153                         goto out;
1154                 }
1155                 PROC_UNLOCK(p);
1156                 error = proc_rwmem(p, &uio);
1157                 piod->piod_len -= uio.uio_resid;
1158                 PROC_LOCK(p);
1159                 break;
1160
1161         case PT_KILL:
1162                 CTR1(KTR_PTRACE, "PT_KILL: pid %d", p->p_pid);
1163                 data = SIGKILL;
1164                 goto sendsig;   /* in PT_CONTINUE above */
1165
1166         case PT_SETREGS:
1167                 CTR2(KTR_PTRACE, "PT_SETREGS: tid %d (pid %d)", td2->td_tid,
1168                     p->p_pid);
1169                 td2->td_dbgflags |= TDB_USERWR;
1170                 error = PROC_WRITE(regs, td2, addr);
1171                 break;
1172
1173         case PT_GETREGS:
1174                 CTR2(KTR_PTRACE, "PT_GETREGS: tid %d (pid %d)", td2->td_tid,
1175                     p->p_pid);
1176                 error = PROC_READ(regs, td2, addr);
1177                 break;
1178
1179         case PT_SETFPREGS:
1180                 CTR2(KTR_PTRACE, "PT_SETFPREGS: tid %d (pid %d)", td2->td_tid,
1181                     p->p_pid);
1182                 td2->td_dbgflags |= TDB_USERWR;
1183                 error = PROC_WRITE(fpregs, td2, addr);
1184                 break;
1185
1186         case PT_GETFPREGS:
1187                 CTR2(KTR_PTRACE, "PT_GETFPREGS: tid %d (pid %d)", td2->td_tid,
1188                     p->p_pid);
1189                 error = PROC_READ(fpregs, td2, addr);
1190                 break;
1191
1192         case PT_SETDBREGS:
1193                 CTR2(KTR_PTRACE, "PT_SETDBREGS: tid %d (pid %d)", td2->td_tid,
1194                     p->p_pid);
1195                 td2->td_dbgflags |= TDB_USERWR;
1196                 error = PROC_WRITE(dbregs, td2, addr);
1197                 break;
1198
1199         case PT_GETDBREGS:
1200                 CTR2(KTR_PTRACE, "PT_GETDBREGS: tid %d (pid %d)", td2->td_tid,
1201                     p->p_pid);
1202                 error = PROC_READ(dbregs, td2, addr);
1203                 break;
1204
1205         case PT_LWPINFO:
1206                 if (data <= 0 || data > sizeof(*pl)) {
1207                         error = EINVAL;
1208                         break;
1209                 }
1210                 pl = addr;
1211                 bzero(pl, sizeof(*pl));
1212                 pl->pl_lwpid = td2->td_tid;
1213                 pl->pl_event = PL_EVENT_NONE;
1214                 pl->pl_flags = 0;
1215                 if (td2->td_dbgflags & TDB_XSIG) {
1216                         pl->pl_event = PL_EVENT_SIGNAL;
1217                         if (td2->td_si.si_signo != 0 &&
1218                             data >= offsetof(struct ptrace_lwpinfo, pl_siginfo)
1219                             + sizeof(pl->pl_siginfo)){
1220                                 pl->pl_flags |= PL_FLAG_SI;
1221                                 pl->pl_siginfo = td2->td_si;
1222                         }
1223                 }
1224                 if (td2->td_dbgflags & TDB_SCE)
1225                         pl->pl_flags |= PL_FLAG_SCE;
1226                 else if (td2->td_dbgflags & TDB_SCX)
1227                         pl->pl_flags |= PL_FLAG_SCX;
1228                 if (td2->td_dbgflags & TDB_EXEC)
1229                         pl->pl_flags |= PL_FLAG_EXEC;
1230                 if (td2->td_dbgflags & TDB_FORK) {
1231                         pl->pl_flags |= PL_FLAG_FORKED;
1232                         pl->pl_child_pid = td2->td_dbg_forked;
1233                         if (td2->td_dbgflags & TDB_VFORK)
1234                                 pl->pl_flags |= PL_FLAG_VFORKED;
1235                 } else if ((td2->td_dbgflags & (TDB_SCX | TDB_VFORK)) ==
1236                     TDB_VFORK)
1237                         pl->pl_flags |= PL_FLAG_VFORK_DONE;
1238                 if (td2->td_dbgflags & TDB_CHILD)
1239                         pl->pl_flags |= PL_FLAG_CHILD;
1240                 if (td2->td_dbgflags & TDB_BORN)
1241                         pl->pl_flags |= PL_FLAG_BORN;
1242                 if (td2->td_dbgflags & TDB_EXIT)
1243                         pl->pl_flags |= PL_FLAG_EXITED;
1244                 pl->pl_sigmask = td2->td_sigmask;
1245                 pl->pl_siglist = td2->td_siglist;
1246                 strcpy(pl->pl_tdname, td2->td_name);
1247                 if ((td2->td_dbgflags & (TDB_SCE | TDB_SCX)) != 0) {
1248                         pl->pl_syscall_code = td2->td_sa.code;
1249                         pl->pl_syscall_narg = td2->td_sa.callp->sy_narg;
1250                 } else {
1251                         pl->pl_syscall_code = 0;
1252                         pl->pl_syscall_narg = 0;
1253                 }
1254                 CTR6(KTR_PTRACE,
1255     "PT_LWPINFO: tid %d (pid %d) event %d flags %#x child pid %d syscall %d",
1256                     td2->td_tid, p->p_pid, pl->pl_event, pl->pl_flags,
1257                     pl->pl_child_pid, pl->pl_syscall_code);
1258                 break;
1259
1260         case PT_GETNUMLWPS:
1261                 CTR2(KTR_PTRACE, "PT_GETNUMLWPS: pid %d: %d threads", p->p_pid,
1262                     p->p_numthreads);
1263                 td->td_retval[0] = p->p_numthreads;
1264                 break;
1265
1266         case PT_GETLWPLIST:
1267                 CTR3(KTR_PTRACE, "PT_GETLWPLIST: pid %d: data %d, actual %d",
1268                     p->p_pid, data, p->p_numthreads);
1269                 if (data <= 0) {
1270                         error = EINVAL;
1271                         break;
1272                 }
1273                 num = imin(p->p_numthreads, data);
1274                 PROC_UNLOCK(p);
1275                 buf = malloc(num * sizeof(lwpid_t), M_TEMP, M_WAITOK);
1276                 tmp = 0;
1277                 PROC_LOCK(p);
1278                 FOREACH_THREAD_IN_PROC(p, td2) {
1279                         if (tmp >= num)
1280                                 break;
1281                         buf[tmp++] = td2->td_tid;
1282                 }
1283                 PROC_UNLOCK(p);
1284                 error = copyout(buf, addr, tmp * sizeof(lwpid_t));
1285                 free(buf, M_TEMP);
1286                 if (!error)
1287                         td->td_retval[0] = tmp;
1288                 PROC_LOCK(p);
1289                 break;
1290
1291         case PT_VM_TIMESTAMP:
1292                 CTR2(KTR_PTRACE, "PT_VM_TIMESTAMP: pid %d: timestamp %d",
1293                     p->p_pid, p->p_vmspace->vm_map.timestamp);
1294                 td->td_retval[0] = p->p_vmspace->vm_map.timestamp;
1295                 break;
1296
1297         case PT_VM_ENTRY:
1298                 PROC_UNLOCK(p);
1299                 error = ptrace_vm_entry(td, p, addr);
1300                 PROC_LOCK(p);
1301                 break;
1302
1303         default:
1304 #ifdef __HAVE_PTRACE_MACHDEP
1305                 if (req >= PT_FIRSTMACH) {
1306                         PROC_UNLOCK(p);
1307                         error = cpu_ptrace(td2, req, addr, data);
1308                         PROC_LOCK(p);
1309                 } else
1310 #endif
1311                         /* Unknown request. */
1312                         error = EINVAL;
1313                 break;
1314         }
1315
1316 out:
1317         /* Drop our hold on this process now that the request has completed. */
1318         _PRELE(p);
1319 fail:
1320         PROC_UNLOCK(p);
1321         if (proctree_locked)
1322                 sx_xunlock(&proctree_lock);
1323         return (error);
1324 }
1325 #undef PROC_READ
1326 #undef PROC_WRITE