- Always set td_dbg_sc_* when P_TRACED is set on system call entry even if the debugger is not tracing system call entries. This ensures the fields are valid when reporting other stops that occur at system call boundaries such as for PT_FOLLOW_FORKS or when only tracing system call exits. - Set TDB_SCX when reporting the stop for a new child process in fork_return(). This causes the event to be reported as a system call exit. - Report a system call exit event in fork_return() for new threads in a traced process. - Copy td_dbg_sc_* to new threads instead of zeroing. This ensures that td_dbg_sc_code in particular will report the system call that created the new thread or process when it reports a system call exit event in fork_return(). - Add new ptrace tests to verify that new child processes and threads report system call exit events with a valid pl_syscall_code via PT_LWPINFO. Reviewed by: kib Differential Revision: https://reviews.freebsd.org/D3822
253 lines
7.3 KiB
C
253 lines
7.3 KiB
C
/*-
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* Copyright (C) 1994, David Greenman
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* Copyright (c) 1990, 1993
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* The Regents of the University of California. All rights reserved.
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* Copyright (C) 2010 Konstantin Belousov <kib@freebsd.org>
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*
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* This code is derived from software contributed to Berkeley by
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* the University of Utah, and William Jolitz.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* from: @(#)trap.c 7.4 (Berkeley) 5/13/91
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*/
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#include "opt_capsicum.h"
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#include "opt_ktrace.h"
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__FBSDID("$FreeBSD$");
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#include <sys/capsicum.h>
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#include <sys/ktr.h>
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#ifdef KTRACE
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#include <sys/uio.h>
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#include <sys/ktrace.h>
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#endif
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#include <security/audit/audit.h>
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static inline int
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syscallenter(struct thread *td, struct syscall_args *sa)
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{
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struct proc *p;
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int error, traced;
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PCPU_INC(cnt.v_syscall);
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p = td->td_proc;
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td->td_pticks = 0;
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if (td->td_cowgen != p->p_cowgen)
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thread_cow_update(td);
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traced = (p->p_flag & P_TRACED) != 0;
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if (traced || td->td_dbgflags & TDB_USERWR) {
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PROC_LOCK(p);
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td->td_dbgflags &= ~TDB_USERWR;
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if (traced)
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td->td_dbgflags |= TDB_SCE;
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PROC_UNLOCK(p);
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}
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error = (p->p_sysent->sv_fetch_syscall_args)(td, sa);
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#ifdef KTRACE
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if (KTRPOINT(td, KTR_SYSCALL))
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ktrsyscall(sa->code, sa->narg, sa->args);
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#endif
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KTR_START4(KTR_SYSC, "syscall", syscallname(p, sa->code),
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(uintptr_t)td, "pid:%d", td->td_proc->p_pid, "arg0:%p", sa->args[0],
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"arg1:%p", sa->args[1], "arg2:%p", sa->args[2]);
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if (error == 0) {
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STOPEVENT(p, S_SCE, sa->narg);
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if (p->p_flag & P_TRACED) {
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PROC_LOCK(p);
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td->td_dbg_sc_code = sa->code;
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td->td_dbg_sc_narg = sa->narg;
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if (p->p_stops & S_PT_SCE)
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ptracestop((td), SIGTRAP);
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PROC_UNLOCK(p);
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}
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if (td->td_dbgflags & TDB_USERWR) {
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/*
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* Reread syscall number and arguments if
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* debugger modified registers or memory.
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*/
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error = (p->p_sysent->sv_fetch_syscall_args)(td, sa);
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PROC_LOCK(p);
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td->td_dbg_sc_code = sa->code;
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td->td_dbg_sc_narg = sa->narg;
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PROC_UNLOCK(p);
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#ifdef KTRACE
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if (KTRPOINT(td, KTR_SYSCALL))
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ktrsyscall(sa->code, sa->narg, sa->args);
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#endif
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if (error != 0)
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goto retval;
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}
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#ifdef CAPABILITY_MODE
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/*
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* In capability mode, we only allow access to system calls
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* flagged with SYF_CAPENABLED.
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*/
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if (IN_CAPABILITY_MODE(td) &&
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!(sa->callp->sy_flags & SYF_CAPENABLED)) {
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error = ECAPMODE;
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goto retval;
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}
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#endif
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error = syscall_thread_enter(td, sa->callp);
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if (error != 0)
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goto retval;
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#ifdef KDTRACE_HOOKS
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/*
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* If the systrace module has registered it's probe
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* callback and if there is a probe active for the
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* syscall 'entry', process the probe.
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*/
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if (systrace_probe_func != NULL && sa->callp->sy_entry != 0)
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(*systrace_probe_func)(sa->callp->sy_entry, sa->code,
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sa->callp, sa->args, 0);
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#endif
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AUDIT_SYSCALL_ENTER(sa->code, td);
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error = (sa->callp->sy_call)(td, sa->args);
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AUDIT_SYSCALL_EXIT(error, td);
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/* Save the latest error return value. */
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if ((td->td_pflags & TDP_NERRNO) == 0)
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td->td_errno = error;
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#ifdef KDTRACE_HOOKS
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/*
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* If the systrace module has registered it's probe
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* callback and if there is a probe active for the
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* syscall 'return', process the probe.
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*/
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if (systrace_probe_func != NULL && sa->callp->sy_return != 0)
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(*systrace_probe_func)(sa->callp->sy_return, sa->code,
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sa->callp, NULL, (error) ? -1 : td->td_retval[0]);
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#endif
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syscall_thread_exit(td, sa->callp);
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}
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retval:
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KTR_STOP4(KTR_SYSC, "syscall", syscallname(p, sa->code),
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(uintptr_t)td, "pid:%d", td->td_proc->p_pid, "error:%d", error,
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"retval0:%#lx", td->td_retval[0], "retval1:%#lx",
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td->td_retval[1]);
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if (traced) {
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PROC_LOCK(p);
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td->td_dbgflags &= ~TDB_SCE;
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PROC_UNLOCK(p);
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}
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(p->p_sysent->sv_set_syscall_retval)(td, error);
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return (error);
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}
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static inline void
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syscallret(struct thread *td, int error, struct syscall_args *sa)
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{
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struct proc *p, *p2;
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int traced;
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p = td->td_proc;
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/*
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* Handle reschedule and other end-of-syscall issues
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*/
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userret(td, td->td_frame);
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#ifdef KTRACE
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if (KTRPOINT(td, KTR_SYSRET)) {
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ktrsysret(sa->code, (td->td_pflags & TDP_NERRNO) == 0 ?
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error : td->td_errno, td->td_retval[0]);
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}
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#endif
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td->td_pflags &= ~TDP_NERRNO;
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if (p->p_flag & P_TRACED) {
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traced = 1;
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PROC_LOCK(p);
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td->td_dbgflags |= TDB_SCX;
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PROC_UNLOCK(p);
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} else
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traced = 0;
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/*
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* This works because errno is findable through the
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* register set. If we ever support an emulation where this
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* is not the case, this code will need to be revisited.
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*/
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STOPEVENT(p, S_SCX, sa->code);
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if (traced || (td->td_dbgflags & (TDB_EXEC | TDB_FORK)) != 0) {
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PROC_LOCK(p);
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/*
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* If tracing the execed process, trap to the debugger
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* so that breakpoints can be set before the program
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* executes. If debugger requested tracing of syscall
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* returns, do it now too.
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*/
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if (traced &&
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((td->td_dbgflags & (TDB_FORK | TDB_EXEC)) != 0 ||
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(p->p_stops & S_PT_SCX) != 0))
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ptracestop(td, SIGTRAP);
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td->td_dbgflags &= ~(TDB_SCX | TDB_EXEC | TDB_FORK);
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PROC_UNLOCK(p);
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}
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if (td->td_pflags & TDP_RFPPWAIT) {
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/*
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* Preserve synchronization semantics of vfork. If
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* waiting for child to exec or exit, fork set
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* P_PPWAIT on child, and there we sleep on our proc
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* (in case of exit).
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*
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* Do it after the ptracestop() above is finished, to
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* not block our debugger until child execs or exits
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* to finish vfork wait.
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*/
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td->td_pflags &= ~TDP_RFPPWAIT;
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p2 = td->td_rfppwait_p;
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again:
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PROC_LOCK(p2);
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while (p2->p_flag & P_PPWAIT) {
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PROC_LOCK(p);
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if (thread_suspend_check_needed()) {
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PROC_UNLOCK(p2);
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thread_suspend_check(0);
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PROC_UNLOCK(p);
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goto again;
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} else {
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PROC_UNLOCK(p);
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}
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cv_timedwait(&p2->p_pwait, &p2->p_mtx, hz);
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}
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PROC_UNLOCK(p2);
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}
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}
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