FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_trap.c
1 /*-
2 * Copyright (C) 1994, David Greenman
3 * Copyright (c) 1990, 1993
4 * The Regents of the University of California. All rights reserved.
5 *
6 * This code is derived from software contributed to Berkeley by
7 * the University of Utah, and William Jolitz.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 * 3. All advertising materials mentioning features or use of this software
18 * must display the following acknowledgement:
19 * This product includes software developed by the University of
20 * California, Berkeley and its contributors.
21 * 4. Neither the name of the University nor the names of its contributors
22 * may be used to endorse or promote products derived from this software
23 * without specific prior written permission.
24 *
25 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
28 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
35 * SUCH DAMAGE.
36 *
37 * from: @(#)trap.c 7.4 (Berkeley) 5/13/91
38 */
39
40 #include <sys/cdefs.h>
41 __FBSDID("$FreeBSD: releng/6.0/sys/kern/subr_trap.c 144223 2005-03-28 12:52:46Z jeff $");
42
43 #include "opt_ktrace.h"
44 #include "opt_mac.h"
45 #ifdef __i386__
46 #include "opt_npx.h"
47 #endif
48
49 #include <sys/param.h>
50 #include <sys/bus.h>
51 #include <sys/kernel.h>
52 #include <sys/lock.h>
53 #include <sys/mac.h>
54 #include <sys/mutex.h>
55 #include <sys/proc.h>
56 #include <sys/ktr.h>
57 #include <sys/resourcevar.h>
58 #include <sys/sched.h>
59 #include <sys/signalvar.h>
60 #include <sys/systm.h>
61 #include <sys/vmmeter.h>
62 #ifdef KTRACE
63 #include <sys/uio.h>
64 #include <sys/ktrace.h>
65 #endif
66
67 #include <machine/cpu.h>
68 #include <machine/pcb.h>
69
70 /*
71 * Define the code needed before returning to user mode, for
72 * trap and syscall.
73 *
74 * MPSAFE
75 */
76 void
77 userret(td, frame, oticks)
78 struct thread *td;
79 struct trapframe *frame;
80 u_int oticks;
81 {
82 struct proc *p = td->td_proc;
83
84 CTR3(KTR_SYSC, "userret: thread %p (pid %d, %s)", td, p->p_pid,
85 p->p_comm);
86 #ifdef DIAGNOSTIC
87 /* Check that we called signotify() enough. */
88 PROC_LOCK(p);
89 mtx_lock_spin(&sched_lock);
90 if (SIGPENDING(td) && ((td->td_flags & TDF_NEEDSIGCHK) == 0 ||
91 (td->td_flags & TDF_ASTPENDING) == 0))
92 printf("failed to set signal flags properly for ast()\n");
93 mtx_unlock_spin(&sched_lock);
94 PROC_UNLOCK(p);
95 #endif
96
97 /*
98 * If this thread tickled GEOM, we need to wait for the giggling to
99 * stop before we return to userland
100 */
101 if (td->td_pflags & TDP_GEOM)
102 g_waitidle();
103
104 /*
105 * We need to check to see if we have to exit or wait due to a
106 * single threading requirement or some other STOP condition.
107 * Don't bother doing all the work if the stop bits are not set
108 * at this time.. If we miss it, we miss it.. no big deal.
109 */
110 if (P_SHOULDSTOP(p)) {
111 PROC_LOCK(p);
112 thread_suspend_check(0); /* Can suspend or kill */
113 PROC_UNLOCK(p);
114 }
115
116 /*
117 * Do special thread processing, e.g. upcall tweaking and such.
118 */
119 if (p->p_flag & P_SA)
120 thread_userret(td, frame);
121
122 /*
123 * Charge system time if profiling.
124 */
125 if (p->p_flag & P_PROFIL) {
126 quad_t ticks;
127
128 ticks = td->td_sticks - oticks;
129 addupc_task(td, TRAPF_PC(frame), (u_int)ticks * psratio);
130 }
131
132 /*
133 * Let the scheduler adjust our priority etc.
134 */
135 sched_userret(td);
136 KASSERT(td->td_locks == 0,
137 ("userret: Returning with %d locks held.", td->td_locks));
138 }
139
140 /*
141 * Process an asynchronous software trap.
142 * This is relatively easy.
143 * This function will return with preemption disabled.
144 */
145 void
146 ast(struct trapframe *framep)
147 {
148 struct thread *td;
149 struct proc *p;
150 struct ksegrp *kg;
151 struct rlimit rlim;
152 u_int sticks;
153 int sflag;
154 int flags;
155 int sig;
156 #if defined(DEV_NPX) && !defined(SMP)
157 int ucode;
158 #endif
159
160 td = curthread;
161 p = td->td_proc;
162 kg = td->td_ksegrp;
163
164 CTR3(KTR_SYSC, "ast: thread %p (pid %d, %s)", td, p->p_pid,
165 p->p_comm);
166 KASSERT(TRAPF_USERMODE(framep), ("ast in kernel mode"));
167 WITNESS_WARN(WARN_PANIC, NULL, "Returning to user mode");
168 mtx_assert(&Giant, MA_NOTOWNED);
169 mtx_assert(&sched_lock, MA_NOTOWNED);
170 td->td_frame = framep;
171 sticks = td->td_sticks;
172
173 if ((p->p_flag & P_SA) && (td->td_mailbox == NULL))
174 thread_user_enter(td);
175
176 /*
177 * This updates the p_sflag's for the checks below in one
178 * "atomic" operation with turning off the astpending flag.
179 * If another AST is triggered while we are handling the
180 * AST's saved in sflag, the astpending flag will be set and
181 * ast() will be called again.
182 */
183 mtx_lock_spin(&sched_lock);
184 flags = td->td_flags;
185 sflag = p->p_sflag;
186 p->p_sflag &= ~(PS_ALRMPEND | PS_PROFPEND | PS_XCPU);
187 #ifdef MAC
188 p->p_sflag &= ~PS_MACPEND;
189 #endif
190 td->td_flags &= ~(TDF_ASTPENDING | TDF_NEEDSIGCHK |
191 TDF_NEEDRESCHED | TDF_INTERRUPT);
192 cnt.v_soft++;
193 mtx_unlock_spin(&sched_lock);
194
195 /*
196 * XXXKSE While the fact that we owe a user profiling
197 * tick is stored per KSE in this code, the statistics
198 * themselves are still stored per process.
199 * This should probably change, by which I mean that
200 * possibly the location of both might change.
201 */
202 if (td->td_ucred != p->p_ucred)
203 cred_update_thread(td);
204 if (td->td_pflags & TDP_OWEUPC && p->p_flag & P_PROFIL) {
205 addupc_task(td, td->td_profil_addr, td->td_profil_ticks);
206 td->td_profil_ticks = 0;
207 td->td_pflags &= ~TDP_OWEUPC;
208 }
209 if (sflag & PS_ALRMPEND) {
210 PROC_LOCK(p);
211 psignal(p, SIGVTALRM);
212 PROC_UNLOCK(p);
213 }
214 #if defined(DEV_NPX) && !defined(SMP)
215 if (PCPU_GET(curpcb)->pcb_flags & PCB_NPXTRAP) {
216 atomic_clear_int(&PCPU_GET(curpcb)->pcb_flags,
217 PCB_NPXTRAP);
218 ucode = npxtrap();
219 if (ucode != -1) {
220 trapsignal(td, SIGFPE, ucode);
221 }
222 }
223 #endif
224 if (sflag & PS_PROFPEND) {
225 PROC_LOCK(p);
226 psignal(p, SIGPROF);
227 PROC_UNLOCK(p);
228 }
229 if (sflag & PS_XCPU) {
230 PROC_LOCK(p);
231 lim_rlimit(p, RLIMIT_CPU, &rlim);
232 mtx_lock_spin(&sched_lock);
233 if (p->p_rux.rux_runtime.sec >= rlim.rlim_max) {
234 mtx_unlock_spin(&sched_lock);
235 killproc(p, "exceeded maximum CPU limit");
236 } else {
237 if (p->p_cpulimit < rlim.rlim_max)
238 p->p_cpulimit += 5;
239 mtx_unlock_spin(&sched_lock);
240 psignal(p, SIGXCPU);
241 }
242 PROC_UNLOCK(p);
243 }
244 #ifdef MAC
245 if (sflag & PS_MACPEND)
246 mac_thread_userret(td);
247 #endif
248 if (flags & TDF_NEEDRESCHED) {
249 #ifdef KTRACE
250 if (KTRPOINT(td, KTR_CSW))
251 ktrcsw(1, 1);
252 #endif
253 mtx_lock_spin(&sched_lock);
254 sched_prio(td, kg->kg_user_pri);
255 mi_switch(SW_INVOL, NULL);
256 mtx_unlock_spin(&sched_lock);
257 #ifdef KTRACE
258 if (KTRPOINT(td, KTR_CSW))
259 ktrcsw(0, 1);
260 #endif
261 }
262 if (flags & TDF_NEEDSIGCHK) {
263 PROC_LOCK(p);
264 mtx_lock(&p->p_sigacts->ps_mtx);
265 while ((sig = cursig(td)) != 0)
266 postsig(sig);
267 mtx_unlock(&p->p_sigacts->ps_mtx);
268 PROC_UNLOCK(p);
269 }
270
271 userret(td, framep, sticks);
272 mtx_assert(&Giant, MA_NOTOWNED);
273 }
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