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 "opt_compat.h"
  36
  37 #include <sys/param.h>
  38 #include <sys/systm.h>
  39 #include <sys/lock.h>
  40 #include <sys/mutex.h>
  41 #include <sys/syscallsubr.h>
  42 #include <sys/sysent.h>
  43 #include <sys/sysproto.h>
  44 #include <sys/priv.h>
  45 #include <sys/proc.h>
  46 #include <sys/vnode.h>
  47 #include <sys/ptrace.h>
  48 #include <sys/rwlock.h>
  49 #include <sys/sx.h>
  50 #include <sys/malloc.h>
  51 #include <sys/signalvar.h>
  52
  53 #include <machine/reg.h>
  54
  55 #include <security/audit/audit.h>
  56
  57 #include <vm/vm.h>
  58 #include <vm/pmap.h>
  59 #include <vm/vm_extern.h>
  60 #include <vm/vm_map.h>
  61 #include <vm/vm_kern.h>
  62 #include <vm/vm_object.h>
  63 #include <vm/vm_page.h>
  64 #include <vm/vm_param.h>
  65
  66 #ifdef COMPAT_FREEBSD32
  67 #include <sys/procfs.h>
  68 #include <compat/freebsd32/freebsd32_signal.h>
  69
  70 struct ptrace_io_desc32 {
  71         int             piod_op;
  72         uint32_t        piod_offs;
  73         uint32_t        piod_addr;
  74         uint32_t        piod_len;
  75 };
  76
  77 struct ptrace_vm_entry32 {
  78         int             pve_entry;
  79         int             pve_timestamp;
  80         uint32_t        pve_start;
  81         uint32_t        pve_end;
  82         uint32_t        pve_offset;
  83         u_int           pve_prot;
  84         u_int           pve_pathlen;
  85         int32_t         pve_fileid;
  86         u_int           pve_fsid;
  87         uint32_t        pve_path;
  88 };
  89
  90 struct ptrace_lwpinfo32 {
  91         lwpid_t pl_lwpid;       /* LWP described. */
  92         int     pl_event;       /* Event that stopped the LWP. */
  93         int     pl_flags;       /* LWP flags. */
  94         sigset_t        pl_sigmask;     /* LWP signal mask */
  95         sigset_t        pl_siglist;     /* LWP pending signal */
  96         struct siginfo32 pl_siginfo;    /* siginfo for signal */
  97         char    pl_tdname[MAXCOMLEN + 1];       /* LWP name. */
  98         pid_t   pl_child_pid;           /* New child pid */
  99         u_int           pl_syscall_code;
 100         u_int           pl_syscall_narg;
 101 };
 102
 103 #endif
 104
 105 /*
 106  * Functions implemented using PROC_ACTION():
 107  *
 108  * proc_read_regs(proc, regs)
 109  *      Get the current user-visible register set from the process
 110  *      and copy it into the regs structure (<machine/reg.h>).
 111  *      The process is stopped at the time read_regs is called.
 112  *
 113  * proc_write_regs(proc, regs)
 114  *      Update the current register set from the passed in regs
 115  *      structure.  Take care to avoid clobbering special CPU
 116  *      registers or privileged bits in the PSL.
 117  *      Depending on the architecture this may have fix-up work to do,
 118  *      especially if the IAR or PCW are modified.
 119  *      The process is stopped at the time write_regs is called.
 120  *
 121  * proc_read_fpregs, proc_write_fpregs
 122  *      deal with the floating point register set, otherwise as above.
 123  *
 124  * proc_read_dbregs, proc_write_dbregs
 125  *      deal with the processor debug register set, otherwise as above.
 126  *
 127  * proc_sstep(proc)
 128  *      Arrange for the process to trap after executing a single instruction.
 129  */
 130
 131 #define PROC_ACTION(action) do {                                        \
 132         int error;                                                      \
 133                                                                         \
 134         PROC_LOCK_ASSERT(td->td_proc, MA_OWNED);                        \
 135         if ((td->td_proc->p_flag & P_INMEM) == 0)                       \
 136                 error = EIO;                                            \
 137         else                                                            \
 138                 error = (action);                                       \
 139         return (error);                                                 \
 140 } while(0)
 141
 142 int
 143 proc_read_regs(struct thread *td, struct reg *regs)
 144 {
 145
 146         PROC_ACTION(fill_regs(td, regs));
 147 }
 148
 149 int
 150 proc_write_regs(struct thread *td, struct reg *regs)
 151 {
 152
 153         PROC_ACTION(set_regs(td, regs));
 154 }
 155
 156 int
 157 proc_read_dbregs(struct thread *td, struct dbreg *dbregs)
 158 {
 159
 160         PROC_ACTION(fill_dbregs(td, dbregs));
 161 }
 162
 163 int
 164 proc_write_dbregs(struct thread *td, struct dbreg *dbregs)
 165 {
 166
 167         PROC_ACTION(set_dbregs(td, dbregs));
 168 }
 169
 170 /*
 171  * Ptrace doesn't support fpregs at all, and there are no security holes
 172  * or translations for fpregs, so we can just copy them.
 173  */
 174 int
 175 proc_read_fpregs(struct thread *td, struct fpreg *fpregs)
 176 {
 177
 178         PROC_ACTION(fill_fpregs(td, fpregs));
 179 }
 180
 181 int
 182 proc_write_fpregs(struct thread *td, struct fpreg *fpregs)
 183 {
 184
 185         PROC_ACTION(set_fpregs(td, fpregs));
 186 }
 187
 188 #ifdef COMPAT_FREEBSD32
 189 /* For 32 bit binaries, we need to expose the 32 bit regs layouts. */
 190 int
 191 proc_read_regs32(struct thread *td, struct reg32 *regs32)
 192 {
 193
 194         PROC_ACTION(fill_regs32(td, regs32));
 195 }
 196
 197 int
 198 proc_write_regs32(struct thread *td, struct reg32 *regs32)
 199 {
 200
 201         PROC_ACTION(set_regs32(td, regs32));
 202 }
 203
 204 int
 205 proc_read_dbregs32(struct thread *td, struct dbreg32 *dbregs32)
 206 {
 207
 208         PROC_ACTION(fill_dbregs32(td, dbregs32));
 209 }
 210
 211 int
 212 proc_write_dbregs32(struct thread *td, struct dbreg32 *dbregs32)
 213 {
 214
 215         PROC_ACTION(set_dbregs32(td, dbregs32));
 216 }
 217
 218 int
 219 proc_read_fpregs32(struct thread *td, struct fpreg32 *fpregs32)
 220 {
 221
 222         PROC_ACTION(fill_fpregs32(td, fpregs32));
 223 }
 224
 225 int
 226 proc_write_fpregs32(struct thread *td, struct fpreg32 *fpregs32)
 227 {
 228
 229         PROC_ACTION(set_fpregs32(td, fpregs32));
 230 }
 231 #endif
 232
 233 int
 234 proc_sstep(struct thread *td)
 235 {
 236
 237         PROC_ACTION(ptrace_single_step(td));
 238 }
 239
 240 int
 241 proc_rwmem(struct proc *p, struct uio *uio)
 242 {
 243         vm_map_t map;
 244         vm_offset_t pageno;             /* page number */
 245         vm_prot_t reqprot;
 246         int error, fault_flags, page_offset, writing;
 247
 248         /*
 249          * Assert that someone has locked this vmspace.  (Should be
 250          * curthread but we can't assert that.)  This keeps the process
 251          * from exiting out from under us until this operation completes.
 252          */
 253         KASSERT(p->p_lock >= 1, ("%s: process %p (pid %d) not held", __func__,
 254             p, p->p_pid));
 255
 256         /*
 257          * The map we want...
 258          */
 259         map = &p->p_vmspace->vm_map;
 260
 261         /*
 262          * If we are writing, then we request vm_fault() to create a private
 263          * copy of each page.  Since these copies will not be writeable by the
 264          * process, we must explicity request that they be dirtied.
 265          */
 266         writing = uio->uio_rw == UIO_WRITE;
 267         reqprot = writing ? VM_PROT_COPY | VM_PROT_READ : VM_PROT_READ;
 268         fault_flags = writing ? VM_FAULT_DIRTY : VM_FAULT_NORMAL;
 269
 270         /*
 271          * Only map in one page at a time.  We don't have to, but it
 272          * makes things easier.  This way is trivial - right?
 273          */
 274         do {
 275                 vm_offset_t uva;
 276                 u_int len;
 277                 vm_page_t m;
 278
 279                 uva = (vm_offset_t)uio->uio_offset;
 280
 281                 /*
 282                  * Get the page number of this segment.
 283                  */
 284                 pageno = trunc_page(uva);
 285                 page_offset = uva - pageno;
 286
 287                 /*
 288                  * How many bytes to copy
 289                  */
 290                 len = min(PAGE_SIZE - page_offset, uio->uio_resid);
 291
 292                 /*
 293                  * Fault and hold the page on behalf of the process.
 294                  */
 295                 error = vm_fault_hold(map, pageno, reqprot, fault_flags, &m);
 296                 if (error != KERN_SUCCESS) {
 297                         if (error == KERN_RESOURCE_SHORTAGE)
 298                                 error = ENOMEM;
 299                         else
 300                                 error = EFAULT;
 301                         break;
 302                 }
 303
 304                 /*
 305                  * Now do the i/o move.
 306                  */
 307                 error = uiomove_fromphys(&m, page_offset, len, uio);
 308
 309                 /* Make the I-cache coherent for breakpoints. */
 310                 if (writing && error == 0) {
 311                         vm_map_lock_read(map);
 312                         if (vm_map_check_protection(map, pageno, pageno +
 313                             PAGE_SIZE, VM_PROT_EXECUTE))
 314                                 vm_sync_icache(map, uva, len);
 315                         vm_map_unlock_read(map);
 316                 }
 317
 318                 /*
 319                  * Release the page.
 320                  */
 321                 vm_page_lock(m);
 322                 vm_page_unhold(m);
 323                 vm_page_unlock(m);
 324
 325         } while (error == 0 && uio->uio_resid > 0);
 326
 327         return (error);
 328 }
 329
 330 static int
 331 ptrace_vm_entry(struct thread *td, struct proc *p, struct ptrace_vm_entry *pve)
 332 {
 333         struct vattr vattr;
 334         vm_map_t map;
 335         vm_map_entry_t entry;
 336         vm_object_t obj, tobj, lobj;
 337         struct vmspace *vm;
 338         struct vnode *vp;
 339         char *freepath, *fullpath;
 340         u_int pathlen;
 341         int error, index;
 342
 343         error = 0;
 344         obj = NULL;
 345
 346         vm = vmspace_acquire_ref(p);
 347         map = &vm->vm_map;
 348         vm_map_lock_read(map);
 349
 350         do {
 351                 entry = map->header.next;
 352                 index = 0;
 353                 while (index < pve->pve_entry && entry != &map->header) {
 354                         entry = entry->next;
 355                         index++;
 356                 }
 357                 if (index != pve->pve_entry) {
 358                         error = EINVAL;
 359                         break;
 360                 }
 361                 while (entry != &map->header &&
 362                     (entry->eflags & MAP_ENTRY_IS_SUB_MAP) != 0) {
 363                         entry = entry->next;
 364                         index++;
 365                 }
 366                 if (entry == &map->header) {
 367                         error = ENOENT;
 368                         break;
 369                 }
 370
 371                 /* We got an entry. */
 372                 pve->pve_entry = index + 1;
 373                 pve->pve_timestamp = map->timestamp;
 374                 pve->pve_start = entry->start;
 375                 pve->pve_end = entry->end - 1;
 376                 pve->pve_offset = entry->offset;
 377                 pve->pve_prot = entry->protection;
 378
 379                 /* Backing object's path needed? */
 380                 if (pve->pve_pathlen == 0)
 381                         break;
 382
 383                 pathlen = pve->pve_pathlen;
 384                 pve->pve_pathlen = 0;
 385
 386                 obj = entry->object.vm_object;
 387                 if (obj != NULL)
 388                         VM_OBJECT_RLOCK(obj);
 389         } while (0);
 390
 391         vm_map_unlock_read(map);
 392         vmspace_free(vm);
 393
 394         pve->pve_fsid = VNOVAL;
 395         pve->pve_fileid = VNOVAL;
 396
 397         if (error == 0 && obj != NULL) {
 398                 lobj = obj;
 399                 for (tobj = obj; tobj != NULL; tobj = tobj->backing_object) {
 400                         if (tobj != obj)
 401                                 VM_OBJECT_RLOCK(tobj);
 402                         if (lobj != obj)
 403                                 VM_OBJECT_RUNLOCK(lobj);
 404                         lobj = tobj;
 405                         pve->pve_offset += tobj->backing_object_offset;
 406                 }
 407                 vp = vm_object_vnode(lobj);
 408                 if (vp != NULL)
 409                         vref(vp);
 410                 if (lobj != obj)
 411                         VM_OBJECT_RUNLOCK(lobj);
 412                 VM_OBJECT_RUNLOCK(obj);
 413
 414                 if (vp != NULL) {
 415                         freepath = NULL;
 416                         fullpath = NULL;
 417                         vn_fullpath(td, vp, &fullpath, &freepath);
 418                         vn_lock(vp, LK_SHARED | LK_RETRY);
 419                         if (VOP_GETATTR(vp, &vattr, td->td_ucred) == 0) {
 420                                 pve->pve_fileid = vattr.va_fileid;
 421                                 pve->pve_fsid = vattr.va_fsid;
 422                         }
 423                         vput(vp);
 424
 425                         if (fullpath != NULL) {
 426                                 pve->pve_pathlen = strlen(fullpath) + 1;
 427                                 if (pve->pve_pathlen <= pathlen) {
 428                                         error = copyout(fullpath, pve->pve_path,
 429                                             pve->pve_pathlen);
 430                                 } else
 431                                         error = ENAMETOOLONG;
 432                         }
 433                         if (freepath != NULL)
 434                                 free(freepath, M_TEMP);
 435                 }
 436         }
 437         if (error == 0)
 438                 CTR3(KTR_PTRACE, "PT_VM_ENTRY: pid %d, entry %d, start %p",
 439                     p->p_pid, pve->pve_entry, pve->pve_start);
 440
 441         return (error);
 442 }
 443
 444 #ifdef COMPAT_FREEBSD32
 445 static int
 446 ptrace_vm_entry32(struct thread *td, struct proc *p,
 447     struct ptrace_vm_entry32 *pve32)
 448 {
 449         struct ptrace_vm_entry pve;
 450         int error;
 451
 452         pve.pve_entry = pve32->pve_entry;
 453         pve.pve_pathlen = pve32->pve_pathlen;
 454         pve.pve_path = (void *)(uintptr_t)pve32->pve_path;
 455
 456         error = ptrace_vm_entry(td, p, &pve);
 457         if (error == 0) {
 458                 pve32->pve_entry = pve.pve_entry;
 459                 pve32->pve_timestamp = pve.pve_timestamp;
 460                 pve32->pve_start = pve.pve_start;
 461                 pve32->pve_end = pve.pve_end;
 462                 pve32->pve_offset = pve.pve_offset;
 463                 pve32->pve_prot = pve.pve_prot;
 464                 pve32->pve_fileid = pve.pve_fileid;
 465                 pve32->pve_fsid = pve.pve_fsid;
 466         }
 467
 468         pve32->pve_pathlen = pve.pve_pathlen;
 469         return (error);
 470 }
 471
 472 static void
 473 ptrace_lwpinfo_to32(const struct ptrace_lwpinfo *pl,
 474     struct ptrace_lwpinfo32 *pl32)
 475 {
 476
 477         bzero(pl32, sizeof(*pl32));
 478         pl32->pl_lwpid = pl->pl_lwpid;
 479         pl32->pl_event = pl->pl_event;
 480         pl32->pl_flags = pl->pl_flags;
 481         pl32->pl_sigmask = pl->pl_sigmask;
 482         pl32->pl_siglist = pl->pl_siglist;
 483         siginfo_to_siginfo32(&pl->pl_siginfo, &pl32->pl_siginfo);
 484         strcpy(pl32->pl_tdname, pl->pl_tdname);
 485         pl32->pl_child_pid = pl->pl_child_pid;
 486         pl32->pl_syscall_code = pl->pl_syscall_code;
 487         pl32->pl_syscall_narg = pl->pl_syscall_narg;
 488 }
 489 #endif /* COMPAT_FREEBSD32 */
 490
 491 /*
 492  * Process debugging system call.
 493  */
 494 #ifndef _SYS_SYSPROTO_H_
 495 struct ptrace_args {
 496         int     req;
 497         pid_t   pid;
 498         caddr_t addr;
 499         int     data;
 500 };
 501 #endif
 502
 503 #ifdef COMPAT_FREEBSD32
 504 /*
 505  * This CPP subterfuge is to try and reduce the number of ifdefs in
 506  * the body of the code.
 507  *   COPYIN(uap->addr, &r.reg, sizeof r.reg);
 508  * becomes either:
 509  *   copyin(uap->addr, &r.reg, sizeof r.reg);
 510  * or
 511  *   copyin(uap->addr, &r.reg32, sizeof r.reg32);
 512  * .. except this is done at runtime.
 513  */
 514 #define COPYIN(u, k, s)         wrap32 ? \
 515         copyin(u, k ## 32, s ## 32) : \
 516         copyin(u, k, s)
 517 #define COPYOUT(k, u, s)        wrap32 ? \
 518         copyout(k ## 32, u, s ## 32) : \
 519         copyout(k, u, s)
 520 #else
 521 #define COPYIN(u, k, s)         copyin(u, k, s)
 522 #define COPYOUT(k, u, s)        copyout(k, u, s)
 523 #endif
 524 int
 525 sys_ptrace(struct thread *td, struct ptrace_args *uap)
 526 {
 527         /*
 528          * XXX this obfuscation is to reduce stack usage, but the register
 529          * structs may be too large to put on the stack anyway.
 530          */
 531         union {
 532                 struct ptrace_io_desc piod;
 533                 struct ptrace_lwpinfo pl;
 534                 struct ptrace_vm_entry pve;
 535                 struct dbreg dbreg;
 536                 struct fpreg fpreg;
 537                 struct reg reg;
 538 #ifdef COMPAT_FREEBSD32
 539                 struct dbreg32 dbreg32;
 540                 struct fpreg32 fpreg32;
 541                 struct reg32 reg32;
 542                 struct ptrace_io_desc32 piod32;
 543                 struct ptrace_lwpinfo32 pl32;
 544                 struct ptrace_vm_entry32 pve32;
 545 #endif
 546         } r;
 547         void *addr;
 548         int error = 0;
 549 #ifdef COMPAT_FREEBSD32
 550         int wrap32 = 0;
 551
 552         if (SV_CURPROC_FLAG(SV_ILP32))
 553                 wrap32 = 1;
 554 #endif
 555         AUDIT_ARG_PID(uap->pid);
 556         AUDIT_ARG_CMD(uap->req);
 557         AUDIT_ARG_VALUE(uap->data);
 558         addr = &r;
 559         switch (uap->req) {
 560         case PT_GETREGS:
 561         case PT_GETFPREGS:
 562         case PT_GETDBREGS:
 563         case PT_LWPINFO:
 564                 break;
 565         case PT_SETREGS:
 566                 error = COPYIN(uap->addr, &r.reg, sizeof r.reg);
 567                 break;
 568         case PT_SETFPREGS:
 569                 error = COPYIN(uap->addr, &r.fpreg, sizeof r.fpreg);
 570                 break;
 571         case PT_SETDBREGS:
 572                 error = COPYIN(uap->addr, &r.dbreg, sizeof r.dbreg);
 573                 break;
 574         case PT_IO:
 575                 error = COPYIN(uap->addr, &r.piod, sizeof r.piod);
 576                 break;
 577         case PT_VM_ENTRY:
 578                 error = COPYIN(uap->addr, &r.pve, sizeof r.pve);
 579                 break;
 580         default:
 581                 addr = uap->addr;
 582                 break;
 583         }
 584         if (error)
 585                 return (error);
 586
 587         error = kern_ptrace(td, uap->req, uap->pid, addr, uap->data);
 588         if (error)
 589                 return (error);
 590
 591         switch (uap->req) {
 592         case PT_VM_ENTRY:
 593                 error = COPYOUT(&r.pve, uap->addr, sizeof r.pve);
 594                 break;
 595         case PT_IO:
 596                 error = COPYOUT(&r.piod, uap->addr, sizeof r.piod);
 597                 break;
 598         case PT_GETREGS:
 599                 error = COPYOUT(&r.reg, uap->addr, sizeof r.reg);
 600                 break;
 601         case PT_GETFPREGS:
 602                 error = COPYOUT(&r.fpreg, uap->addr, sizeof r.fpreg);
 603                 break;
 604         case PT_GETDBREGS:
 605                 error = COPYOUT(&r.dbreg, uap->addr, sizeof r.dbreg);
 606                 break;
 607         case PT_LWPINFO:
 608                 error = copyout(&r.pl, uap->addr, uap->data);
 609                 break;
 610         }
 611
 612         return (error);
 613 }
 614 #undef COPYIN
 615 #undef COPYOUT
 616
 617 #ifdef COMPAT_FREEBSD32
 618 /*
 619  *   PROC_READ(regs, td2, addr);
 620  * becomes either:
 621  *   proc_read_regs(td2, addr);
 622  * or
 623  *   proc_read_regs32(td2, addr);
 624  * .. except this is done at runtime.  There is an additional
 625  * complication in that PROC_WRITE disallows 32 bit consumers
 626  * from writing to 64 bit address space targets.
 627  */
 628 #define PROC_READ(w, t, a)      wrap32 ? \
 629         proc_read_ ## w ## 32(t, a) : \
 630         proc_read_ ## w (t, a)
 631 #define PROC_WRITE(w, t, a)     wrap32 ? \
 632         (safe ? proc_write_ ## w ## 32(t, a) : EINVAL ) : \
 633         proc_write_ ## w (t, a)
 634 #else
 635 #define PROC_READ(w, t, a)      proc_read_ ## w (t, a)
 636 #define PROC_WRITE(w, t, a)     proc_write_ ## w (t, a)
 637 #endif
 638
 639 int
 640 kern_ptrace(struct thread *td, int req, pid_t pid, void *addr, int data)
 641 {
 642         struct iovec iov;
 643         struct uio uio;
 644         struct proc *curp, *p, *pp;
 645         struct thread *td2 = NULL, *td3;
 646         struct ptrace_io_desc *piod = NULL;
 647         struct ptrace_lwpinfo *pl;
 648         int error, write, tmp, num;
 649         int proctree_locked = 0;
 650         lwpid_t tid = 0, *buf;
 651 #ifdef COMPAT_FREEBSD32
 652         int wrap32 = 0, safe = 0;
 653         struct ptrace_io_desc32 *piod32 = NULL;
 654         struct ptrace_lwpinfo32 *pl32 = NULL;
 655         struct ptrace_lwpinfo plr;
 656 #endif
 657
 658         curp = td->td_proc;
 659
 660         /* Lock proctree before locking the process. */
 661         switch (req) {
 662         case PT_TRACE_ME:
 663         case PT_ATTACH:
 664         case PT_STEP:
 665         case PT_CONTINUE:
 666         case PT_TO_SCE:
 667         case PT_TO_SCX:
 668         case PT_SYSCALL:
 669         case PT_FOLLOW_FORK:
 670         case PT_DETACH:
 671                 sx_xlock(&proctree_lock);
 672                 proctree_locked = 1;
 673                 break;
 674         default:
 675                 break;
 676         }
 677
 678         write = 0;
 679         if (req == PT_TRACE_ME) {
 680                 p = td->td_proc;
 681                 PROC_LOCK(p);
 682         } else {
 683                 if (pid <= PID_MAX) {
 684                         if ((p = pfind(pid)) == NULL) {
 685                                 if (proctree_locked)
 686                                         sx_xunlock(&proctree_lock);
 687                                 return (ESRCH);
 688                         }
 689                 } else {
 690                         td2 = tdfind(pid, -1);
 691                         if (td2 == NULL) {
 692                                 if (proctree_locked)
 693                                         sx_xunlock(&proctree_lock);
 694                                 return (ESRCH);
 695                         }
 696                         p = td2->td_proc;
 697                         tid = pid;
 698                         pid = p->p_pid;
 699                 }
 700         }
 701         AUDIT_ARG_PROCESS(p);
 702
 703         if ((p->p_flag & P_WEXIT) != 0) {
 704                 error = ESRCH;
 705                 goto fail;
 706         }
 707         if ((error = p_cansee(td, p)) != 0)
 708                 goto fail;
 709
 710         if ((error = p_candebug(td, p)) != 0)
 711                 goto fail;
 712
 713         /*
 714          * System processes can't be debugged.
 715          */
 716         if ((p->p_flag & P_SYSTEM) != 0) {
 717                 error = EINVAL;
 718                 goto fail;
 719         }
 720
 721         if (tid == 0) {
 722                 if ((p->p_flag & P_STOPPED_TRACE) != 0) {
 723                         KASSERT(p->p_xthread != NULL, ("NULL p_xthread"));
 724                         td2 = p->p_xthread;
 725                 } else {
 726                         td2 = FIRST_THREAD_IN_PROC(p);
 727                 }
 728                 tid = td2->td_tid;
 729         }
 730
 731 #ifdef COMPAT_FREEBSD32
 732         /*
 733          * Test if we're a 32 bit client and what the target is.
 734          * Set the wrap controls accordingly.
 735          */
 736         if (SV_CURPROC_FLAG(SV_ILP32)) {
 737                 if (SV_PROC_FLAG(td2->td_proc, SV_ILP32))
 738                         safe = 1;
 739                 wrap32 = 1;
 740         }
 741 #endif
 742         /*
 743          * Permissions check
 744          */
 745         switch (req) {
 746         case PT_TRACE_ME:
 747                 /*
 748                  * Always legal, when there is a parent process which
 749                  * could trace us.  Otherwise, reject.
 750                  */
 751                 if ((p->p_flag & P_TRACED) != 0) {
 752                         error = EBUSY;
 753                         goto fail;
 754                 }
 755                 if (p->p_pptr == initproc) {
 756                         error = EPERM;
 757                         goto fail;
 758                 }
 759                 break;
 760
 761         case PT_ATTACH:
 762                 /* Self */
 763                 if (p == td->td_proc) {
 764                         error = EINVAL;
 765                         goto fail;
 766                 }
 767
 768                 /* Already traced */
 769                 if (p->p_flag & P_TRACED) {
 770                         error = EBUSY;
 771                         goto fail;
 772                 }
 773
 774                 /* Can't trace an ancestor if you're being traced. */
 775                 if (curp->p_flag & P_TRACED) {
 776                         for (pp = curp->p_pptr; pp != NULL; pp = pp->p_pptr) {
 777                                 if (pp == p) {
 778                                         error = EINVAL;
 779                                         goto fail;
 780                                 }
 781                         }
 782                 }
 783
 784
 785                 /* OK */
 786                 break;
 787
 788         case PT_CLEARSTEP:
 789                 /* Allow thread to clear single step for itself */
 790                 if (td->td_tid == tid)
 791                         break;
 792
 793                 /* FALLTHROUGH */
 794         default:
 795                 /* not being traced... */
 796                 if ((p->p_flag & P_TRACED) == 0) {
 797                         error = EPERM;
 798                         goto fail;
 799                 }
 800
 801                 /* not being traced by YOU */
 802                 if (p->p_pptr != td->td_proc) {
 803                         error = EBUSY;
 804                         goto fail;
 805                 }
 806
 807                 /* not currently stopped */
 808                 if ((p->p_flag & (P_STOPPED_SIG | P_STOPPED_TRACE)) == 0 ||
 809                     p->p_suspcount != p->p_numthreads  ||
 810                     (p->p_flag & P_WAITED) == 0) {
 811                         error = EBUSY;
 812                         goto fail;
 813                 }
 814
 815                 if ((p->p_flag & P_STOPPED_TRACE) == 0) {
 816                         static int count = 0;
 817                         if (count++ == 0)
 818                                 printf("P_STOPPED_TRACE not set.\n");
 819                 }
 820
 821                 /* OK */
 822                 break;
 823         }
 824
 825         /* Keep this process around until we finish this request. */
 826         _PHOLD(p);
 827
 828 #ifdef FIX_SSTEP
 829         /*
 830          * Single step fixup ala procfs
 831          */
 832         FIX_SSTEP(td2);
 833 #endif
 834
 835         /*
 836          * Actually do the requests
 837          */
 838
 839         td->td_retval[0] = 0;
 840
 841         switch (req) {
 842         case PT_TRACE_ME:
 843                 /* set my trace flag and "owner" so it can read/write me */
 844                 p->p_flag |= P_TRACED;
 845                 if (p->p_flag & P_PPWAIT)
 846                         p->p_flag |= P_PPTRACE;
 847                 p->p_oppid = p->p_pptr->p_pid;
 848                 CTR1(KTR_PTRACE, "PT_TRACE_ME: pid %d", p->p_pid);
 849                 break;
 850
 851         case PT_ATTACH:
 852                 /* security check done above */
 853                 /*
 854                  * It would be nice if the tracing relationship was separate
 855                  * from the parent relationship but that would require
 856                  * another set of links in the proc struct or for "wait"
 857                  * to scan the entire proc table.  To make life easier,
 858                  * we just re-parent the process we're trying to trace.
 859                  * The old parent is remembered so we can put things back
 860                  * on a "detach".
 861                  */
 862                 p->p_flag |= P_TRACED;
 863                 p->p_oppid = p->p_pptr->p_pid;
 864                 if (p->p_pptr != td->td_proc) {
 865                         proc_reparent(p, td->td_proc);
 866                 }
 867                 data = SIGSTOP;
 868                 CTR2(KTR_PTRACE, "PT_ATTACH: pid %d, oppid %d", p->p_pid,
 869                     p->p_oppid);
 870                 goto sendsig;   /* in PT_CONTINUE below */
 871
 872         case PT_CLEARSTEP:
 873                 CTR2(KTR_PTRACE, "PT_CLEARSTEP: tid %d (pid %d)", td2->td_tid,
 874                     p->p_pid);
 875                 error = ptrace_clear_single_step(td2);
 876                 break;
 877
 878         case PT_SETSTEP:
 879                 CTR2(KTR_PTRACE, "PT_SETSTEP: tid %d (pid %d)", td2->td_tid,
 880                     p->p_pid);
 881                 error = ptrace_single_step(td2);
 882                 break;
 883
 884         case PT_SUSPEND:
 885                 CTR2(KTR_PTRACE, "PT_SUSPEND: tid %d (pid %d)", td2->td_tid,
 886                     p->p_pid);
 887                 td2->td_dbgflags |= TDB_SUSPEND;
 888                 thread_lock(td2);
 889                 td2->td_flags |= TDF_NEEDSUSPCHK;
 890                 thread_unlock(td2);
 891                 break;
 892
 893         case PT_RESUME:
 894                 CTR2(KTR_PTRACE, "PT_RESUME: tid %d (pid %d)", td2->td_tid,
 895                     p->p_pid);
 896                 td2->td_dbgflags &= ~TDB_SUSPEND;
 897                 break;
 898
 899         case PT_FOLLOW_FORK:
 900                 CTR3(KTR_PTRACE, "PT_FOLLOW_FORK: pid %d %s -> %s", p->p_pid,
 901                     p->p_flag & P_FOLLOWFORK ? "enabled" : "disabled",
 902                     data ? "enabled" : "disabled");
 903                 if (data)
 904                         p->p_flag |= P_FOLLOWFORK;
 905                 else
 906                         p->p_flag &= ~P_FOLLOWFORK;
 907                 break;
 908
 909         case PT_STEP:
 910         case PT_CONTINUE:
 911         case PT_TO_SCE:
 912         case PT_TO_SCX:
 913         case PT_SYSCALL:
 914         case PT_DETACH:
 915                 /* Zero means do not send any signal */
 916                 if (data < 0 || data > _SIG_MAXSIG) {
 917                         error = EINVAL;
 918                         break;
 919                 }
 920
 921                 switch (req) {
 922                 case PT_STEP:
 923                         CTR2(KTR_PTRACE, "PT_STEP: tid %d (pid %d)",
 924                             td2->td_tid, p->p_pid);
 925                         error = ptrace_single_step(td2);
 926                         if (error)
 927                                 goto out;
 928                         break;
 929                 case PT_CONTINUE:
 930                 case PT_TO_SCE:
 931                 case PT_TO_SCX:
 932                 case PT_SYSCALL:
 933                         if (addr != (void *)1) {
 934                                 error = ptrace_set_pc(td2,
 935                                     (u_long)(uintfptr_t)addr);
 936                                 if (error)
 937                                         goto out;
 938                         }
 939                         switch (req) {
 940                         case PT_TO_SCE:
 941                                 p->p_stops |= S_PT_SCE;
 942                                 CTR4(KTR_PTRACE,
 943                     "PT_TO_SCE: pid %d, stops = %#x, PC = %#lx, sig = %d",
 944                                     p->p_pid, p->p_stops,
 945                                     (u_long)(uintfptr_t)addr, data);
 946                                 break;
 947                         case PT_TO_SCX:
 948                                 p->p_stops |= S_PT_SCX;
 949                                 CTR4(KTR_PTRACE,
 950                     "PT_TO_SCX: pid %d, stops = %#x, PC = %#lx, sig = %d",
 951                                     p->p_pid, p->p_stops,
 952                                     (u_long)(uintfptr_t)addr, data);
 953                                 break;
 954                         case PT_SYSCALL:
 955                                 p->p_stops |= S_PT_SCE | S_PT_SCX;
 956                                 CTR4(KTR_PTRACE,
 957                     "PT_SYSCALL: pid %d, stops = %#x, PC = %#lx, sig = %d",
 958                                     p->p_pid, p->p_stops,
 959                                     (u_long)(uintfptr_t)addr, data);
 960                                 break;
 961                         case PT_CONTINUE:
 962                                 CTR3(KTR_PTRACE,
 963                                     "PT_CONTINUE: pid %d, PC = %#lx, sig = %d",
 964                                     p->p_pid, (u_long)(uintfptr_t)addr, data);
 965                                 break;
 966                         }
 967                         break;
 968                 case PT_DETACH:
 969                         /*
 970                          * Reset the process parent.
 971                          *
 972                          * NB: This clears P_TRACED before reparenting
 973                          * a detached process back to its original
 974                          * parent.  Otherwise the debugee will be set
 975                          * as an orphan of the debugger.
 976                          */
 977                         p->p_flag &= ~(P_TRACED | P_WAITED | P_FOLLOWFORK);
 978                         if (p->p_oppid != p->p_pptr->p_pid) {
 979                                 PROC_LOCK(p->p_pptr);
 980                                 sigqueue_take(p->p_ksi);
 981                                 PROC_UNLOCK(p->p_pptr);
 982
 983                                 pp = proc_realparent(p);
 984                                 proc_reparent(p, pp);
 985                                 if (pp == initproc)
 986                                         p->p_sigparent = SIGCHLD;
 987                                 CTR3(KTR_PTRACE,
 988                             "PT_DETACH: pid %d reparented to pid %d, sig %d",
 989                                     p->p_pid, pp->p_pid, data);
 990                         } else
 991                                 CTR2(KTR_PTRACE, "PT_DETACH: pid %d, sig %d",
 992                                     p->p_pid, data);
 993                         p->p_oppid = 0;
 994                         p->p_stops = 0;
 995
 996                         /* should we send SIGCHLD? */
 997                         /* childproc_continued(p); */
 998                         break;
 999                 }
1000
1001         sendsig:
1002                 if (proctree_locked) {
1003                         sx_xunlock(&proctree_lock);
1004                         proctree_locked = 0;
1005                 }
1006                 p->p_xstat = data;
1007                 p->p_xthread = NULL;
1008                 if ((p->p_flag & (P_STOPPED_SIG | P_STOPPED_TRACE)) != 0) {
1009                         /* deliver or queue signal */
1010                         td2->td_dbgflags &= ~TDB_XSIG;
1011                         td2->td_xsig = data;
1012
1013                         if (req == PT_DETACH) {
1014                                 FOREACH_THREAD_IN_PROC(p, td3)
1015                                         td3->td_dbgflags &= ~TDB_SUSPEND;
1016                         }
1017                         /*
1018                          * unsuspend all threads, to not let a thread run,
1019                          * you should use PT_SUSPEND to suspend it before
1020                          * continuing process.
1021                          */
1022                         PROC_SLOCK(p);
1023                         p->p_flag &= ~(P_STOPPED_TRACE|P_STOPPED_SIG|P_WAITED);
1024                         thread_unsuspend(p);
1025                         PROC_SUNLOCK(p);
1026                         if (req == PT_ATTACH)
1027                                 kern_psignal(p, data);
1028                 } else {
1029                         if (data)
1030                                 kern_psignal(p, data);
1031                 }
1032                 break;
1033
1034         case PT_WRITE_I:
1035         case PT_WRITE_D:
1036                 td2->td_dbgflags |= TDB_USERWR;
1037                 write = 1;
1038                 /* FALLTHROUGH */
1039         case PT_READ_I:
1040         case PT_READ_D:
1041                 PROC_UNLOCK(p);
1042                 tmp = 0;
1043                 /* write = 0 set above */
1044                 iov.iov_base = write ? (caddr_t)&data : (caddr_t)&tmp;
1045                 iov.iov_len = sizeof(int);
1046                 uio.uio_iov = &iov;
1047                 uio.uio_iovcnt = 1;
1048                 uio.uio_offset = (off_t)(uintptr_t)addr;
1049                 uio.uio_resid = sizeof(int);
1050                 uio.uio_segflg = UIO_SYSSPACE;  /* i.e.: the uap */
1051                 uio.uio_rw = write ? UIO_WRITE : UIO_READ;
1052                 uio.uio_td = td;
1053                 error = proc_rwmem(p, &uio);
1054                 if (uio.uio_resid != 0) {
1055                         /*
1056                          * XXX proc_rwmem() doesn't currently return ENOSPC,
1057                          * so I think write() can bogusly return 0.
1058                          * XXX what happens for short writes?  We don't want
1059                          * to write partial data.
1060                          * XXX proc_rwmem() returns EPERM for other invalid
1061                          * addresses.  Convert this to EINVAL.  Does this
1062                          * clobber returns of EPERM for other reasons?
1063                          */
1064                         if (error == 0 || error == ENOSPC || error == EPERM)
1065                                 error = EINVAL; /* EOF */
1066                 }
1067                 if (!write)
1068                         td->td_retval[0] = tmp;
1069                 if (error == 0) {
1070                         if (write)
1071                                 CTR3(KTR_PTRACE, "PT_WRITE: pid %d: %p <= %#x",
1072                                     p->p_pid, addr, data);
1073                         else
1074                                 CTR3(KTR_PTRACE, "PT_READ: pid %d: %p >= %#x",
1075                                     p->p_pid, addr, tmp);
1076                 }
1077                 PROC_LOCK(p);
1078                 break;
1079
1080         case PT_IO:
1081 #ifdef COMPAT_FREEBSD32
1082                 if (wrap32) {
1083                         piod32 = addr;
1084                         iov.iov_base = (void *)(uintptr_t)piod32->piod_addr;
1085                         iov.iov_len = piod32->piod_len;
1086                         uio.uio_offset = (off_t)(uintptr_t)piod32->piod_offs;
1087                         uio.uio_resid = piod32->piod_len;
1088                 } else
1089 #endif
1090                 {
1091                         piod = addr;
1092                         iov.iov_base = piod->piod_addr;
1093                         iov.iov_len = piod->piod_len;
1094                         uio.uio_offset = (off_t)(uintptr_t)piod->piod_offs;
1095                         uio.uio_resid = piod->piod_len;
1096                 }
1097                 uio.uio_iov = &iov;
1098                 uio.uio_iovcnt = 1;
1099                 uio.uio_segflg = UIO_USERSPACE;
1100                 uio.uio_td = td;
1101 #ifdef COMPAT_FREEBSD32
1102                 tmp = wrap32 ? piod32->piod_op : piod->piod_op;
1103 #else
1104                 tmp = piod->piod_op;
1105 #endif
1106                 switch (tmp) {
1107                 case PIOD_READ_D:
1108                 case PIOD_READ_I:
1109                         CTR3(KTR_PTRACE, "PT_IO: pid %d: READ (%p, %#x)",
1110                             p->p_pid, (uintptr_t)uio.uio_offset, uio.uio_resid);
1111                         uio.uio_rw = UIO_READ;
1112                         break;
1113                 case PIOD_WRITE_D:
1114                 case PIOD_WRITE_I:
1115                         CTR3(KTR_PTRACE, "PT_IO: pid %d: WRITE (%p, %#x)",
1116                             p->p_pid, (uintptr_t)uio.uio_offset, uio.uio_resid);
1117                         td2->td_dbgflags |= TDB_USERWR;
1118                         uio.uio_rw = UIO_WRITE;
1119                         break;
1120                 default:
1121                         error = EINVAL;
1122                         goto out;
1123                 }
1124                 PROC_UNLOCK(p);
1125                 error = proc_rwmem(p, &uio);
1126 #ifdef COMPAT_FREEBSD32
1127                 if (wrap32)
1128                         piod32->piod_len -= uio.uio_resid;
1129                 else
1130 #endif
1131                         piod->piod_len -= uio.uio_resid;
1132                 PROC_LOCK(p);
1133                 break;
1134
1135         case PT_KILL:
1136                 CTR1(KTR_PTRACE, "PT_KILL: pid %d", p->p_pid);
1137                 data = SIGKILL;
1138                 goto sendsig;   /* in PT_CONTINUE above */
1139
1140         case PT_SETREGS:
1141                 CTR2(KTR_PTRACE, "PT_SETREGS: tid %d (pid %d)", td2->td_tid,
1142                     p->p_pid);
1143                 td2->td_dbgflags |= TDB_USERWR;
1144                 error = PROC_WRITE(regs, td2, addr);
1145                 break;
1146
1147         case PT_GETREGS:
1148                 CTR2(KTR_PTRACE, "PT_GETREGS: tid %d (pid %d)", td2->td_tid,
1149                     p->p_pid);
1150                 error = PROC_READ(regs, td2, addr);
1151                 break;
1152
1153         case PT_SETFPREGS:
1154                 CTR2(KTR_PTRACE, "PT_SETFPREGS: tid %d (pid %d)", td2->td_tid,
1155                     p->p_pid);
1156                 td2->td_dbgflags |= TDB_USERWR;
1157                 error = PROC_WRITE(fpregs, td2, addr);
1158                 break;
1159
1160         case PT_GETFPREGS:
1161                 CTR2(KTR_PTRACE, "PT_GETFPREGS: tid %d (pid %d)", td2->td_tid,
1162                     p->p_pid);
1163                 error = PROC_READ(fpregs, td2, addr);
1164                 break;
1165
1166         case PT_SETDBREGS:
1167                 CTR2(KTR_PTRACE, "PT_SETDBREGS: tid %d (pid %d)", td2->td_tid,
1168                     p->p_pid);
1169                 td2->td_dbgflags |= TDB_USERWR;
1170                 error = PROC_WRITE(dbregs, td2, addr);
1171                 break;
1172
1173         case PT_GETDBREGS:
1174                 CTR2(KTR_PTRACE, "PT_GETDBREGS: tid %d (pid %d)", td2->td_tid,
1175                     p->p_pid);
1176                 error = PROC_READ(dbregs, td2, addr);
1177                 break;
1178
1179         case PT_LWPINFO:
1180                 if (data <= 0 ||
1181 #ifdef COMPAT_FREEBSD32
1182                     (!wrap32 && data > sizeof(*pl)) ||
1183                     (wrap32 && data > sizeof(*pl32))) {
1184 #else
1185                     data > sizeof(*pl)) {
1186 #endif
1187                         error = EINVAL;
1188                         break;
1189                 }
1190 #ifdef COMPAT_FREEBSD32
1191                 if (wrap32) {
1192                         pl = &plr;
1193                         pl32 = addr;
1194                 } else
1195 #endif
1196                 pl = addr;
1197                 bzero(pl, sizeof(*pl));
1198                 pl->pl_lwpid = td2->td_tid;
1199                 pl->pl_event = PL_EVENT_NONE;
1200                 pl->pl_flags = 0;
1201                 if (td2->td_dbgflags & TDB_XSIG) {
1202                         pl->pl_event = PL_EVENT_SIGNAL;
1203                         if (td2->td_dbgksi.ksi_signo != 0 &&
1204 #ifdef COMPAT_FREEBSD32
1205                             ((!wrap32 && data >= offsetof(struct ptrace_lwpinfo,
1206                             pl_siginfo) + sizeof(pl->pl_siginfo)) ||
1207                             (wrap32 && data >= offsetof(struct ptrace_lwpinfo32,
1208                             pl_siginfo) + sizeof(struct siginfo32)))
1209 #else
1210                             data >= offsetof(struct ptrace_lwpinfo, pl_siginfo)
1211                             + sizeof(pl->pl_siginfo)
1212 #endif
1213                         ){
1214                                 pl->pl_flags |= PL_FLAG_SI;
1215                                 pl->pl_siginfo = td2->td_dbgksi.ksi_info;
1216                         }
1217                 }
1218                 if (td2->td_dbgflags & TDB_SCE)
1219                         pl->pl_flags |= PL_FLAG_SCE;
1220                 else if (td2->td_dbgflags & TDB_SCX)
1221                         pl->pl_flags |= PL_FLAG_SCX;
1222                 if (td2->td_dbgflags & TDB_EXEC)
1223                         pl->pl_flags |= PL_FLAG_EXEC;
1224                 if (td2->td_dbgflags & TDB_FORK) {
1225                         pl->pl_flags |= PL_FLAG_FORKED;
1226                         pl->pl_child_pid = td2->td_dbg_forked;
1227                 }
1228                 if (td2->td_dbgflags & TDB_CHILD)
1229                         pl->pl_flags |= PL_FLAG_CHILD;
1230                 pl->pl_sigmask = td2->td_sigmask;
1231                 pl->pl_siglist = td2->td_siglist;
1232                 strcpy(pl->pl_tdname, td2->td_name);
1233                 if ((td2->td_dbgflags & (TDB_SCE | TDB_SCX)) != 0) {
1234                         pl->pl_syscall_code = td2->td_dbg_sc_code;
1235                         pl->pl_syscall_narg = td2->td_dbg_sc_narg;
1236                 } else {
1237                         pl->pl_syscall_code = 0;
1238                         pl->pl_syscall_narg = 0;
1239                 }
1240 #ifdef COMPAT_FREEBSD32
1241                 if (wrap32)
1242                         ptrace_lwpinfo_to32(pl, pl32);
1243 #endif
1244                 CTR6(KTR_PTRACE,
1245     "PT_LWPINFO: tid %d (pid %d) event %d flags %#x child pid %d syscall %d",
1246                     td2->td_tid, p->p_pid, pl->pl_event, pl->pl_flags,
1247                     pl->pl_child_pid, pl->pl_syscall_code);
1248                 break;
1249
1250         case PT_GETNUMLWPS:
1251                 CTR2(KTR_PTRACE, "PT_GETNUMLWPS: pid %d: %d threads", p->p_pid,
1252                     p->p_numthreads);
1253                 td->td_retval[0] = p->p_numthreads;
1254                 break;
1255
1256         case PT_GETLWPLIST:
1257                 CTR3(KTR_PTRACE, "PT_GETLWPLIST: pid %d: data %d, actual %d",
1258                     p->p_pid, data, p->p_numthreads);
1259                 if (data <= 0) {
1260                         error = EINVAL;
1261                         break;
1262                 }
1263                 num = imin(p->p_numthreads, data);
1264                 PROC_UNLOCK(p);
1265                 buf = malloc(num * sizeof(lwpid_t), M_TEMP, M_WAITOK);
1266                 tmp = 0;
1267                 PROC_LOCK(p);
1268                 FOREACH_THREAD_IN_PROC(p, td2) {
1269                         if (tmp >= num)
1270                                 break;
1271                         buf[tmp++] = td2->td_tid;
1272                 }
1273                 PROC_UNLOCK(p);
1274                 error = copyout(buf, addr, tmp * sizeof(lwpid_t));
1275                 free(buf, M_TEMP);
1276                 if (!error)
1277                         td->td_retval[0] = tmp;
1278                 PROC_LOCK(p);
1279                 break;
1280
1281         case PT_VM_TIMESTAMP:
1282                 CTR2(KTR_PTRACE, "PT_VM_TIMESTAMP: pid %d: timestamp %d",
1283                     p->p_pid, p->p_vmspace->vm_map.timestamp);
1284                 td->td_retval[0] = p->p_vmspace->vm_map.timestamp;
1285                 break;
1286
1287         case PT_VM_ENTRY:
1288                 PROC_UNLOCK(p);
1289 #ifdef COMPAT_FREEBSD32
1290                 if (wrap32)
1291                         error = ptrace_vm_entry32(td, p, addr);
1292                 else
1293 #endif
1294                 error = ptrace_vm_entry(td, p, addr);
1295                 PROC_LOCK(p);
1296                 break;
1297
1298         default:
1299 #ifdef __HAVE_PTRACE_MACHDEP
1300                 if (req >= PT_FIRSTMACH) {
1301                         PROC_UNLOCK(p);
1302                         error = cpu_ptrace(td2, req, addr, data);
1303                         PROC_LOCK(p);
1304                 } else
1305 #endif
1306                         /* Unknown request. */
1307                         error = EINVAL;
1308                 break;
1309         }
1310
1311 out:
1312         /* Drop our hold on this process now that the request has completed. */
1313         _PRELE(p);
1314 fail:
1315         PROC_UNLOCK(p);
1316         if (proctree_locked)
1317                 sx_xunlock(&proctree_lock);
1318         return (error);
1319 }
1320 #undef PROC_READ
1321 #undef PROC_WRITE
1322
1323 /*
1324  * Stop a process because of a debugging event;
1325  * stay stopped until p->p_step is cleared
1326  * (cleared by PIOCCONT in procfs).
1327  */
1328 void
1329 stopevent(struct proc *p, unsigned int event, unsigned int val)
1330 {
1331
1332         PROC_LOCK_ASSERT(p, MA_OWNED);
1333         p->p_step = 1;
1334         CTR3(KTR_PTRACE, "stopevent: pid %d event %u val %u", p->p_pid, event,
1335             val);
1336         do {
1337                 p->p_xstat = val;
1338                 p->p_xthread = NULL;
1339                 p->p_stype = event;     /* Which event caused the stop? */
1340                 wakeup(&p->p_stype);    /* Wake up any PIOCWAIT'ing procs */
1341                 msleep(&p->p_step, &p->p_mtx, PWAIT, "stopevent", 0);
1342         } while (p->p_step);
1343 }