subr_syscall.c revision 177471
1/*-
2 * Copyright (C) 1994, David Greenman
3 * Copyright (c) 1990, 1993
4 *	The Regents of the University of California.  All rights reserved.
5 * Copyright (c) 2007 The FreeBSD Foundation
6 *
7 * This code is derived from software contributed to Berkeley by
8 * the University of Utah, and William Jolitz.
9 *
10 * Portions of this software were developed by A. Joseph Koshy under
11 * sponsorship from the FreeBSD Foundation and Google, Inc.
12 *
13 * Redistribution and use in source and binary forms, with or without
14 * modification, are permitted provided that the following conditions
15 * are met:
16 * 1. Redistributions of source code must retain the above copyright
17 *    notice, this list of conditions and the following disclaimer.
18 * 2. Redistributions in binary form must reproduce the above copyright
19 *    notice, this list of conditions and the following disclaimer in the
20 *    documentation and/or other materials provided with the distribution.
21 * 3. All advertising materials mentioning features or use of this software
22 *    must display the following acknowledgement:
23 *	This product includes software developed by the University of
24 *	California, Berkeley and its contributors.
25 * 4. Neither the name of the University nor the names of its contributors
26 *    may be used to endorse or promote products derived from this software
27 *    without specific prior written permission.
28 *
29 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
30 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
31 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
32 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
33 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
34 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
35 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
36 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
37 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
38 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
39 * SUCH DAMAGE.
40 *
41 *	from: @(#)trap.c	7.4 (Berkeley) 5/13/91
42 */
43
44#include <sys/cdefs.h>
45__FBSDID("$FreeBSD: head/sys/kern/subr_trap.c 177471 2008-03-21 08:23:25Z jeff $");
46
47#include "opt_hwpmc_hooks.h"
48#include "opt_ktrace.h"
49#include "opt_mac.h"
50#ifdef __i386__
51#include "opt_npx.h"
52#endif
53#include "opt_sched.h"
54
55#include <sys/param.h>
56#include <sys/bus.h>
57#include <sys/kernel.h>
58#include <sys/lock.h>
59#include <sys/mutex.h>
60#include <sys/pmckern.h>
61#include <sys/proc.h>
62#include <sys/ktr.h>
63#include <sys/resourcevar.h>
64#include <sys/sched.h>
65#include <sys/signalvar.h>
66#include <sys/systm.h>
67#include <sys/vmmeter.h>
68#ifdef KTRACE
69#include <sys/uio.h>
70#include <sys/ktrace.h>
71#endif
72
73#include <machine/cpu.h>
74#include <machine/pcb.h>
75
76#include <security/mac/mac_framework.h>
77
78/*
79 * Define the code needed before returning to user mode, for trap and
80 * syscall.
81 */
82void
83userret(struct thread *td, struct trapframe *frame)
84{
85	struct proc *p = td->td_proc;
86
87	CTR3(KTR_SYSC, "userret: thread %p (pid %d, %s)", td, p->p_pid,
88            td->td_name);
89#ifdef DIAGNOSTIC
90	/* Check that we called signotify() enough. */
91	PROC_LOCK(p);
92	thread_lock(td);
93	if (SIGPENDING(td) && ((td->td_flags & TDF_NEEDSIGCHK) == 0 ||
94	    (td->td_flags & TDF_ASTPENDING) == 0))
95		printf("failed to set signal flags properly for ast()\n");
96	thread_unlock(td);
97	PROC_UNLOCK(p);
98#endif
99#ifdef KTRACE
100	KTRUSERRET(td);
101#endif
102	/*
103	 * If this thread tickled GEOM, we need to wait for the giggling to
104	 * stop before we return to userland
105	 */
106	if (td->td_pflags & TDP_GEOM)
107		g_waitidle();
108
109	/*
110	 * Charge system time if profiling.
111	 */
112	if (p->p_flag & P_PROFIL) {
113		addupc_task(td, TRAPF_PC(frame), td->td_pticks * psratio);
114	}
115	/*
116	 * Let the scheduler adjust our priority etc.
117	 */
118	sched_userret(td);
119	KASSERT(td->td_locks == 0,
120	    ("userret: Returning with %d locks held.", td->td_locks));
121}
122
123/*
124 * Process an asynchronous software trap.
125 * This is relatively easy.
126 * This function will return with preemption disabled.
127 */
128void
129ast(struct trapframe *framep)
130{
131	struct thread *td;
132	struct proc *p;
133	int flags;
134	int sig;
135#if defined(DEV_NPX) && !defined(SMP)
136	int ucode;
137	ksiginfo_t ksi;
138#endif
139
140	td = curthread;
141	p = td->td_proc;
142
143	CTR3(KTR_SYSC, "ast: thread %p (pid %d, %s)", td, p->p_pid,
144            p->p_comm);
145	KASSERT(TRAPF_USERMODE(framep), ("ast in kernel mode"));
146	WITNESS_WARN(WARN_PANIC, NULL, "Returning to user mode");
147	mtx_assert(&Giant, MA_NOTOWNED);
148	THREAD_LOCK_ASSERT(td, MA_NOTOWNED);
149	td->td_frame = framep;
150	td->td_pticks = 0;
151
152	/*
153	 * This updates the td_flag's for the checks below in one
154	 * "atomic" operation with turning off the astpending flag.
155	 * If another AST is triggered while we are handling the
156	 * AST's saved in flags, the astpending flag will be set and
157	 * ast() will be called again.
158	 */
159	thread_lock(td);
160	flags = td->td_flags;
161	td->td_flags &= ~(TDF_ASTPENDING | TDF_NEEDSIGCHK | TDF_NEEDSUSPCHK |
162	    TDF_NEEDRESCHED | TDF_ALRMPEND | TDF_PROFPEND | TDF_MACPEND);
163	thread_unlock(td);
164	PCPU_INC(cnt.v_trap);
165
166	if (td->td_ucred != p->p_ucred)
167		cred_update_thread(td);
168	if (td->td_pflags & TDP_OWEUPC && p->p_flag & P_PROFIL) {
169		addupc_task(td, td->td_profil_addr, td->td_profil_ticks);
170		td->td_profil_ticks = 0;
171		td->td_pflags &= ~TDP_OWEUPC;
172	}
173#if defined(HWPMC_HOOKS)
174	if (td->td_pflags & TDP_CALLCHAIN) {
175		PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_USER_CALLCHAIN,
176		    (void *) framep);
177		td->td_pflags &= ~TDP_CALLCHAIN;
178	}
179#endif
180	if (flags & TDF_ALRMPEND) {
181		PROC_LOCK(p);
182		psignal(p, SIGVTALRM);
183		PROC_UNLOCK(p);
184	}
185#if defined(DEV_NPX) && !defined(SMP)
186	if (PCPU_GET(curpcb)->pcb_flags & PCB_NPXTRAP) {
187		atomic_clear_int(&PCPU_GET(curpcb)->pcb_flags,
188		    PCB_NPXTRAP);
189		ucode = npxtrap();
190		if (ucode != -1) {
191			ksiginfo_init_trap(&ksi);
192			ksi.ksi_signo = SIGFPE;
193			ksi.ksi_code = ucode;
194			trapsignal(td, &ksi);
195		}
196	}
197#endif
198	if (flags & TDF_PROFPEND) {
199		PROC_LOCK(p);
200		psignal(p, SIGPROF);
201		PROC_UNLOCK(p);
202	}
203#ifdef MAC
204	if (flags & TDF_MACPEND)
205		mac_thread_userret(td);
206#endif
207	if (flags & TDF_NEEDRESCHED) {
208#ifdef KTRACE
209		if (KTRPOINT(td, KTR_CSW))
210			ktrcsw(1, 1);
211#endif
212		thread_lock(td);
213		sched_prio(td, td->td_user_pri);
214		SCHED_STAT_INC(switch_needresched);
215		mi_switch(SW_INVOL, NULL);
216		thread_unlock(td);
217#ifdef KTRACE
218		if (KTRPOINT(td, KTR_CSW))
219			ktrcsw(0, 1);
220#endif
221	}
222	if (flags & TDF_NEEDSIGCHK) {
223		PROC_LOCK(p);
224		mtx_lock(&p->p_sigacts->ps_mtx);
225		while ((sig = cursig(td)) != 0)
226			postsig(sig);
227		mtx_unlock(&p->p_sigacts->ps_mtx);
228		PROC_UNLOCK(p);
229	}
230	/*
231	 * We need to check to see if we have to exit or wait due to a
232	 * single threading requirement or some other STOP condition.
233	 */
234	if (flags & TDF_NEEDSUSPCHK) {
235		PROC_LOCK(p);
236		thread_suspend_check(0);
237		PROC_UNLOCK(p);
238	}
239
240	userret(td, framep);
241	mtx_assert(&Giant, MA_NOTOWNED);
242}
243