/*- * Copyright (c) 1994, Sean Eric Fagan * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by Sean Eric Fagan. * 4. The name of the author may not be used to endorse or promote products * derived from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #include __FBSDID("$FreeBSD$"); #include "opt_compat.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef COMPAT_IA32 #include #include #include extern struct sysentvec ia32_freebsd_sysvec; struct ptrace_io_desc32 { int piod_op; u_int32_t piod_offs; u_int32_t piod_addr; u_int32_t piod_len; }; #endif /* * Functions implemented using PROC_ACTION(): * * proc_read_regs(proc, regs) * Get the current user-visible register set from the process * and copy it into the regs structure (). * The process is stopped at the time read_regs is called. * * proc_write_regs(proc, regs) * Update the current register set from the passed in regs * structure. Take care to avoid clobbering special CPU * registers or privileged bits in the PSL. * Depending on the architecture this may have fix-up work to do, * especially if the IAR or PCW are modified. * The process is stopped at the time write_regs is called. * * proc_read_fpregs, proc_write_fpregs * deal with the floating point register set, otherwise as above. * * proc_read_dbregs, proc_write_dbregs * deal with the processor debug register set, otherwise as above. * * proc_sstep(proc) * Arrange for the process to trap after executing a single instruction. */ #define PROC_ACTION(action) do { \ int error; \ \ PROC_LOCK_ASSERT(td->td_proc, MA_OWNED); \ if ((td->td_proc->p_flag & P_INMEM) == 0) \ error = EIO; \ else \ error = (action); \ return (error); \ } while(0) int proc_read_regs(struct thread *td, struct reg *regs) { PROC_ACTION(fill_regs(td, regs)); } int proc_write_regs(struct thread *td, struct reg *regs) { PROC_ACTION(set_regs(td, regs)); } int proc_read_dbregs(struct thread *td, struct dbreg *dbregs) { PROC_ACTION(fill_dbregs(td, dbregs)); } int proc_write_dbregs(struct thread *td, struct dbreg *dbregs) { PROC_ACTION(set_dbregs(td, dbregs)); } /* * Ptrace doesn't support fpregs at all, and there are no security holes * or translations for fpregs, so we can just copy them. */ int proc_read_fpregs(struct thread *td, struct fpreg *fpregs) { PROC_ACTION(fill_fpregs(td, fpregs)); } int proc_write_fpregs(struct thread *td, struct fpreg *fpregs) { PROC_ACTION(set_fpregs(td, fpregs)); } #ifdef COMPAT_IA32 /* For 32 bit binaries, we need to expose the 32 bit regs layouts. */ int proc_read_regs32(struct thread *td, struct reg32 *regs32) { PROC_ACTION(fill_regs32(td, regs32)); } int proc_write_regs32(struct thread *td, struct reg32 *regs32) { PROC_ACTION(set_regs32(td, regs32)); } int proc_read_dbregs32(struct thread *td, struct dbreg32 *dbregs32) { PROC_ACTION(fill_dbregs32(td, dbregs32)); } int proc_write_dbregs32(struct thread *td, struct dbreg32 *dbregs32) { PROC_ACTION(set_dbregs32(td, dbregs32)); } int proc_read_fpregs32(struct thread *td, struct fpreg32 *fpregs32) { PROC_ACTION(fill_fpregs32(td, fpregs32)); } int proc_write_fpregs32(struct thread *td, struct fpreg32 *fpregs32) { PROC_ACTION(set_fpregs32(td, fpregs32)); } #endif int proc_sstep(struct thread *td) { PROC_ACTION(ptrace_single_step(td)); } int proc_rwmem(struct proc *p, struct uio *uio) { vm_map_t map; vm_object_t backing_object, object = NULL; vm_offset_t pageno = 0; /* page number */ vm_prot_t reqprot; int error, fault_flags, writing; /* * Assert that someone has locked this vmspace. (Should be * curthread but we can't assert that.) This keeps the process * from exiting out from under us until this operation completes. */ KASSERT(p->p_lock >= 1, ("%s: process %p (pid %d) not held", __func__, p, p->p_pid)); /* * The map we want... */ map = &p->p_vmspace->vm_map; writing = uio->uio_rw == UIO_WRITE; reqprot = writing ? (VM_PROT_WRITE | VM_PROT_OVERRIDE_WRITE) : VM_PROT_READ; fault_flags = writing ? VM_FAULT_DIRTY : VM_FAULT_NORMAL; /* * Only map in one page at a time. We don't have to, but it * makes things easier. This way is trivial - right? */ do { vm_map_t tmap; vm_offset_t uva; int page_offset; /* offset into page */ vm_map_entry_t out_entry; vm_prot_t out_prot; boolean_t wired; vm_pindex_t pindex; u_int len; vm_page_t m; object = NULL; uva = (vm_offset_t)uio->uio_offset; /* * Get the page number of this segment. */ pageno = trunc_page(uva); page_offset = uva - pageno; /* * How many bytes to copy */ len = min(PAGE_SIZE - page_offset, uio->uio_resid); /* * Fault the page on behalf of the process */ error = vm_fault(map, pageno, reqprot, fault_flags); if (error) { error = EFAULT; break; } /* * Now we need to get the page. out_entry, out_prot, wired, * and single_use aren't used. One would think the vm code * would be a *bit* nicer... We use tmap because * vm_map_lookup() can change the map argument. */ tmap = map; error = vm_map_lookup(&tmap, pageno, reqprot, &out_entry, &object, &pindex, &out_prot, &wired); if (error) { error = EFAULT; break; } VM_OBJECT_LOCK(object); while ((m = vm_page_lookup(object, pindex)) == NULL && !writing && (backing_object = object->backing_object) != NULL) { /* * Allow fallback to backing objects if we are reading. */ VM_OBJECT_LOCK(backing_object); pindex += OFF_TO_IDX(object->backing_object_offset); VM_OBJECT_UNLOCK(object); object = backing_object; } VM_OBJECT_UNLOCK(object); if (m == NULL) { vm_map_lookup_done(tmap, out_entry); error = EFAULT; break; } /* * Hold the page in memory. */ vm_page_lock_queues(); vm_page_hold(m); vm_page_unlock_queues(); /* * We're done with tmap now. */ vm_map_lookup_done(tmap, out_entry); /* * Now do the i/o move. */ error = uiomove_fromphys(&m, page_offset, len, uio); /* * Release the page. */ vm_page_lock_queues(); vm_page_unhold(m); vm_page_unlock_queues(); } while (error == 0 && uio->uio_resid > 0); return (error); } /* * Process debugging system call. */ #ifndef _SYS_SYSPROTO_H_ struct ptrace_args { int req; pid_t pid; caddr_t addr; int data; }; #endif #ifdef COMPAT_IA32 /* * This CPP subterfuge is to try and reduce the number of ifdefs in * the body of the code. * COPYIN(uap->addr, &r.reg, sizeof r.reg); * becomes either: * copyin(uap->addr, &r.reg, sizeof r.reg); * or * copyin(uap->addr, &r.reg32, sizeof r.reg32); * .. except this is done at runtime. */ #define COPYIN(u, k, s) wrap32 ? \ copyin(u, k ## 32, s ## 32) : \ copyin(u, k, s) #define COPYOUT(k, u, s) wrap32 ? \ copyout(k ## 32, u, s ## 32) : \ copyout(k, u, s) #else #define COPYIN(u, k, s) copyin(u, k, s) #define COPYOUT(k, u, s) copyout(k, u, s) #endif int ptrace(struct thread *td, struct ptrace_args *uap) { /* * XXX this obfuscation is to reduce stack usage, but the register * structs may be too large to put on the stack anyway. */ union { struct ptrace_io_desc piod; struct ptrace_lwpinfo pl; struct dbreg dbreg; struct fpreg fpreg; struct reg reg; #ifdef COMPAT_IA32 struct dbreg32 dbreg32; struct fpreg32 fpreg32; struct reg32 reg32; struct ptrace_io_desc32 piod32; #endif } r; void *addr; int error = 0; #ifdef COMPAT_IA32 int wrap32 = 0; if (td->td_proc->p_sysent == &ia32_freebsd_sysvec) wrap32 = 1; #endif AUDIT_ARG(pid, uap->pid); AUDIT_ARG(cmd, uap->req); AUDIT_ARG(addr, uap->addr); AUDIT_ARG(value, uap->data); addr = &r; switch (uap->req) { case PT_GETREGS: case PT_GETFPREGS: case PT_GETDBREGS: case PT_LWPINFO: break; case PT_SETREGS: error = COPYIN(uap->addr, &r.reg, sizeof r.reg); break; case PT_SETFPREGS: error = COPYIN(uap->addr, &r.fpreg, sizeof r.fpreg); break; case PT_SETDBREGS: error = COPYIN(uap->addr, &r.dbreg, sizeof r.dbreg); break; case PT_IO: error = COPYIN(uap->addr, &r.piod, sizeof r.piod); break; default: addr = uap->addr; break; } if (error) return (error); error = kern_ptrace(td, uap->req, uap->pid, addr, uap->data); if (error) return (error); switch (uap->req) { case PT_IO: error = COPYOUT(&r.piod, uap->addr, sizeof r.piod); break; case PT_GETREGS: error = COPYOUT(&r.reg, uap->addr, sizeof r.reg); break; case PT_GETFPREGS: error = COPYOUT(&r.fpreg, uap->addr, sizeof r.fpreg); break; case PT_GETDBREGS: error = COPYOUT(&r.dbreg, uap->addr, sizeof r.dbreg); break; case PT_LWPINFO: error = copyout(&r.pl, uap->addr, uap->data); break; } return (error); } #undef COPYIN #undef COPYOUT #ifdef COMPAT_IA32 /* * PROC_READ(regs, td2, addr); * becomes either: * proc_read_regs(td2, addr); * or * proc_read_regs32(td2, addr); * .. except this is done at runtime. There is an additional * complication in that PROC_WRITE disallows 32 bit consumers * from writing to 64 bit address space targets. */ #define PROC_READ(w, t, a) wrap32 ? \ proc_read_ ## w ## 32(t, a) : \ proc_read_ ## w (t, a) #define PROC_WRITE(w, t, a) wrap32 ? \ (safe ? proc_write_ ## w ## 32(t, a) : EINVAL ) : \ proc_write_ ## w (t, a) #else #define PROC_READ(w, t, a) proc_read_ ## w (t, a) #define PROC_WRITE(w, t, a) proc_write_ ## w (t, a) #endif int kern_ptrace(struct thread *td, int req, pid_t pid, void *addr, int data) { struct iovec iov; struct uio uio; struct proc *curp, *p, *pp; struct thread *td2 = NULL; struct ptrace_io_desc *piod = NULL; struct ptrace_lwpinfo *pl; int error, write, tmp, num; int proctree_locked = 0; lwpid_t tid = 0, *buf; #ifdef COMPAT_IA32 int wrap32 = 0, safe = 0; struct ptrace_io_desc32 *piod32 = NULL; #endif curp = td->td_proc; /* Lock proctree before locking the process. */ switch (req) { case PT_TRACE_ME: case PT_ATTACH: case PT_STEP: case PT_CONTINUE: case PT_TO_SCE: case PT_TO_SCX: case PT_SYSCALL: case PT_DETACH: sx_xlock(&proctree_lock); proctree_locked = 1; break; default: break; } write = 0; if (req == PT_TRACE_ME) { p = td->td_proc; PROC_LOCK(p); } else { if (pid <= PID_MAX) { if ((p = pfind(pid)) == NULL) { if (proctree_locked) sx_xunlock(&proctree_lock); return (ESRCH); } } else { /* this is slow, should be optimized */ sx_slock(&allproc_lock); FOREACH_PROC_IN_SYSTEM(p) { PROC_LOCK(p); PROC_SLOCK(p); FOREACH_THREAD_IN_PROC(p, td2) { if (td2->td_tid == pid) break; } PROC_SUNLOCK(p); if (td2 != NULL) break; /* proc lock held */ PROC_UNLOCK(p); } sx_sunlock(&allproc_lock); if (p == NULL) { if (proctree_locked) sx_xunlock(&proctree_lock); return (ESRCH); } tid = pid; pid = p->p_pid; } } AUDIT_ARG(process, p); if ((p->p_flag & P_WEXIT) != 0) { error = ESRCH; goto fail; } if ((error = p_cansee(td, p)) != 0) goto fail; if ((error = p_candebug(td, p)) != 0) goto fail; /* * System processes can't be debugged. */ if ((p->p_flag & P_SYSTEM) != 0) { error = EINVAL; goto fail; } if (tid == 0) { if ((p->p_flag & P_STOPPED_TRACE) != 0) { KASSERT(p->p_xthread != NULL, ("NULL p_xthread")); td2 = p->p_xthread; } else { td2 = FIRST_THREAD_IN_PROC(p); } tid = td2->td_tid; } #ifdef COMPAT_IA32 /* * Test if we're a 32 bit client and what the target is. * Set the wrap controls accordingly. */ if (td->td_proc->p_sysent == &ia32_freebsd_sysvec) { if (td2->td_proc->p_sysent == &ia32_freebsd_sysvec) safe = 1; wrap32 = 1; } #endif /* * Permissions check */ switch (req) { case PT_TRACE_ME: /* Always legal. */ break; case PT_ATTACH: /* Self */ if (p->p_pid == td->td_proc->p_pid) { error = EINVAL; goto fail; } /* Already traced */ if (p->p_flag & P_TRACED) { error = EBUSY; goto fail; } /* Can't trace an ancestor if you're being traced. */ if (curp->p_flag & P_TRACED) { for (pp = curp->p_pptr; pp != NULL; pp = pp->p_pptr) { if (pp == p) { error = EINVAL; goto fail; } } } /* OK */ break; case PT_CLEARSTEP: /* Allow thread to clear single step for itself */ if (td->td_tid == tid) break; /* FALLTHROUGH */ default: /* not being traced... */ if ((p->p_flag & P_TRACED) == 0) { error = EPERM; goto fail; } /* not being traced by YOU */ if (p->p_pptr != td->td_proc) { error = EBUSY; goto fail; } /* not currently stopped */ if ((p->p_flag & (P_STOPPED_SIG | P_STOPPED_TRACE)) == 0 || p->p_suspcount != p->p_numthreads || (p->p_flag & P_WAITED) == 0) { error = EBUSY; goto fail; } if ((p->p_flag & P_STOPPED_TRACE) == 0) { static int count = 0; if (count++ == 0) printf("P_STOPPED_TRACE not set.\n"); } /* OK */ break; } /* Keep this process around until we finish this request. */ _PHOLD(p); #ifdef FIX_SSTEP /* * Single step fixup ala procfs */ FIX_SSTEP(td2); #endif /* * Actually do the requests */ td->td_retval[0] = 0; switch (req) { case PT_TRACE_ME: /* set my trace flag and "owner" so it can read/write me */ p->p_flag |= P_TRACED; p->p_oppid = p->p_pptr->p_pid; break; case PT_ATTACH: /* security check done above */ p->p_flag |= P_TRACED; p->p_oppid = p->p_pptr->p_pid; if (p->p_pptr != td->td_proc) proc_reparent(p, td->td_proc); data = SIGSTOP; goto sendsig; /* in PT_CONTINUE below */ case PT_CLEARSTEP: error = ptrace_clear_single_step(td2); break; case PT_SETSTEP: error = ptrace_single_step(td2); break; case PT_SUSPEND: thread_lock(td2); td2->td_flags |= TDF_DBSUSPEND; thread_unlock(td2); break; case PT_RESUME: thread_lock(td2); td2->td_flags &= ~TDF_DBSUSPEND; thread_unlock(td2); break; case PT_STEP: case PT_CONTINUE: case PT_TO_SCE: case PT_TO_SCX: case PT_SYSCALL: case PT_DETACH: /* Zero means do not send any signal */ if (data < 0 || data > _SIG_MAXSIG) { error = EINVAL; break; } switch (req) { case PT_STEP: error = ptrace_single_step(td2); if (error) goto out; break; case PT_TO_SCE: p->p_stops |= S_PT_SCE; break; case PT_TO_SCX: p->p_stops |= S_PT_SCX; break; case PT_SYSCALL: p->p_stops |= S_PT_SCE | S_PT_SCX; break; } if (addr != (void *)1) { error = ptrace_set_pc(td2, (u_long)(uintfptr_t)addr); if (error) break; } if (req == PT_DETACH) { /* reset process parent */ if (p->p_oppid != p->p_pptr->p_pid) { struct proc *pp; PROC_LOCK(p->p_pptr); sigqueue_take(p->p_ksi); PROC_UNLOCK(p->p_pptr); PROC_UNLOCK(p); pp = pfind(p->p_oppid); if (pp == NULL) pp = initproc; else PROC_UNLOCK(pp); PROC_LOCK(p); proc_reparent(p, pp); if (pp == initproc) p->p_sigparent = SIGCHLD; } p->p_flag &= ~(P_TRACED | P_WAITED); p->p_oppid = 0; /* should we send SIGCHLD? */ /* childproc_continued(p); */ } sendsig: if (proctree_locked) { sx_xunlock(&proctree_lock); proctree_locked = 0; } p->p_xstat = data; p->p_xthread = NULL; if ((p->p_flag & (P_STOPPED_SIG | P_STOPPED_TRACE)) != 0) { /* deliver or queue signal */ thread_lock(td2); td2->td_flags &= ~TDF_XSIG; thread_unlock(td2); td2->td_xsig = data; PROC_SLOCK(p); if (req == PT_DETACH) { struct thread *td3; FOREACH_THREAD_IN_PROC(p, td3) { thread_lock(td3); td3->td_flags &= ~TDF_DBSUSPEND; thread_unlock(td3); } } /* * unsuspend all threads, to not let a thread run, * you should use PT_SUSPEND to suspend it before * continuing process. */ p->p_flag &= ~(P_STOPPED_TRACE|P_STOPPED_SIG|P_WAITED); thread_unsuspend(p); PROC_SUNLOCK(p); } else { if (data) psignal(p, data); } break; case PT_WRITE_I: case PT_WRITE_D: write = 1; /* FALLTHROUGH */ case PT_READ_I: case PT_READ_D: PROC_UNLOCK(p); tmp = 0; /* write = 0 set above */ iov.iov_base = write ? (caddr_t)&data : (caddr_t)&tmp; iov.iov_len = sizeof(int); uio.uio_iov = &iov; uio.uio_iovcnt = 1; uio.uio_offset = (off_t)(uintptr_t)addr; uio.uio_resid = sizeof(int); uio.uio_segflg = UIO_SYSSPACE; /* i.e.: the uap */ uio.uio_rw = write ? UIO_WRITE : UIO_READ; uio.uio_td = td; error = proc_rwmem(p, &uio); if (uio.uio_resid != 0) { /* * XXX proc_rwmem() doesn't currently return ENOSPC, * so I think write() can bogusly return 0. * XXX what happens for short writes? We don't want * to write partial data. * XXX proc_rwmem() returns EPERM for other invalid * addresses. Convert this to EINVAL. Does this * clobber returns of EPERM for other reasons? */ if (error == 0 || error == ENOSPC || error == EPERM) error = EINVAL; /* EOF */ } if (!write) td->td_retval[0] = tmp; PROC_LOCK(p); break; case PT_IO: #ifdef COMPAT_IA32 if (wrap32) { piod32 = addr; iov.iov_base = (void *)(uintptr_t)piod32->piod_addr; iov.iov_len = piod32->piod_len; uio.uio_offset = (off_t)(uintptr_t)piod32->piod_offs; uio.uio_resid = piod32->piod_len; } else #endif { piod = addr; iov.iov_base = piod->piod_addr; iov.iov_len = piod->piod_len; uio.uio_offset = (off_t)(uintptr_t)piod->piod_offs; uio.uio_resid = piod->piod_len; } uio.uio_iov = &iov; uio.uio_iovcnt = 1; uio.uio_segflg = UIO_USERSPACE; uio.uio_td = td; #ifdef COMPAT_IA32 tmp = wrap32 ? piod32->piod_op : piod->piod_op; #else tmp = piod->piod_op; #endif switch (tmp) { case PIOD_READ_D: case PIOD_READ_I: uio.uio_rw = UIO_READ; break; case PIOD_WRITE_D: case PIOD_WRITE_I: uio.uio_rw = UIO_WRITE; break; default: error = EINVAL; goto out; } PROC_UNLOCK(p); error = proc_rwmem(p, &uio); #ifdef COMPAT_IA32 if (wrap32) piod32->piod_len -= uio.uio_resid; else #endif piod->piod_len -= uio.uio_resid; PROC_LOCK(p); break; case PT_KILL: data = SIGKILL; goto sendsig; /* in PT_CONTINUE above */ case PT_SETREGS: error = PROC_WRITE(regs, td2, addr); break; case PT_GETREGS: error = PROC_READ(regs, td2, addr); break; case PT_SETFPREGS: error = PROC_WRITE(fpregs, td2, addr); break; case PT_GETFPREGS: error = PROC_READ(fpregs, td2, addr); break; case PT_SETDBREGS: error = PROC_WRITE(dbregs, td2, addr); break; case PT_GETDBREGS: error = PROC_READ(dbregs, td2, addr); break; case PT_LWPINFO: if (data <= 0 || data > sizeof(*pl)) { error = EINVAL; break; } pl = addr; pl->pl_lwpid = td2->td_tid; if (td2->td_flags & TDF_XSIG) pl->pl_event = PL_EVENT_SIGNAL; else pl->pl_event = 0; pl->pl_flags = 0; pl->pl_sigmask = td2->td_sigmask; pl->pl_siglist = td2->td_siglist; break; case PT_GETNUMLWPS: td->td_retval[0] = p->p_numthreads; break; case PT_GETLWPLIST: if (data <= 0) { error = EINVAL; break; } num = imin(p->p_numthreads, data); PROC_UNLOCK(p); buf = malloc(num * sizeof(lwpid_t), M_TEMP, M_WAITOK); tmp = 0; PROC_LOCK(p); PROC_SLOCK(p); FOREACH_THREAD_IN_PROC(p, td2) { if (tmp >= num) break; buf[tmp++] = td2->td_tid; } PROC_SUNLOCK(p); PROC_UNLOCK(p); error = copyout(buf, addr, tmp * sizeof(lwpid_t)); free(buf, M_TEMP); if (!error) td->td_retval[0] = tmp; PROC_LOCK(p); break; default: #ifdef __HAVE_PTRACE_MACHDEP if (req >= PT_FIRSTMACH) { PROC_UNLOCK(p); error = cpu_ptrace(td2, req, addr, data); PROC_LOCK(p); } else #endif /* Unknown request. */ error = EINVAL; break; } out: /* Drop our hold on this process now that the request has completed. */ _PRELE(p); fail: PROC_UNLOCK(p); if (proctree_locked) sx_xunlock(&proctree_lock); return (error); } #undef PROC_READ #undef PROC_WRITE /* * Stop a process because of a debugging event; * stay stopped until p->p_step is cleared * (cleared by PIOCCONT in procfs). */ void stopevent(struct proc *p, unsigned int event, unsigned int val) { PROC_LOCK_ASSERT(p, MA_OWNED); p->p_step = 1; do { p->p_xstat = val; p->p_xthread = NULL; p->p_stype = event; /* Which event caused the stop? */ wakeup(&p->p_stype); /* Wake up any PIOCWAIT'ing procs */ msleep(&p->p_step, &p->p_mtx, PWAIT, "stopevent", 0); } while (p->p_step); }