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 * 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: releng/8.3/sys/kern/subr_trap.c 226206 2011-10-10 13:16:39Z kib $");
46
47 #include "opt_ktrace.h"
48 #include "opt_kdtrace.h"
49 #include "opt_sched.h"
50
51 #include <sys/param.h>
52 #include <sys/bus.h>
53 #include <sys/kernel.h>
54 #include <sys/lock.h>
55 #include <sys/mutex.h>
56 #include <sys/pmckern.h>
57 #include <sys/proc.h>
58 #include <sys/ktr.h>
59 #include <sys/pioctl.h>
60 #include <sys/ptrace.h>
61 #include <sys/resourcevar.h>
62 #include <sys/sched.h>
63 #include <sys/signalvar.h>
64 #include <sys/syscall.h>
65 #include <sys/sysent.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 #include <security/audit/audit.h>
73
74 #include <machine/cpu.h>
75
76 #ifdef VIMAGE
77 #include <net/vnet.h>
78 #endif
79
80 #ifdef XEN
81 #include <vm/vm.h>
82 #include <vm/vm_param.h>
83 #include <vm/pmap.h>
84 #endif
85
86 #include <security/mac/mac_framework.h>
87
88 /*
89 * Define the code needed before returning to user mode, for trap and
90 * syscall.
91 */
92 void
93 userret(struct thread *td, struct trapframe *frame)
94 {
95 struct proc *p = td->td_proc;
96
97 CTR3(KTR_SYSC, "userret: thread %p (pid %d, %s)", td, p->p_pid,
98 td->td_name);
99 KASSERT((p->p_flag & P_WEXIT) == 0,
100 ("Exiting process returns to usermode"));
101 #if 0
102 #ifdef DIAGNOSTIC
103 /* Check that we called signotify() enough. */
104 PROC_LOCK(p);
105 thread_lock(td);
106 if (SIGPENDING(td) && ((td->td_flags & TDF_NEEDSIGCHK) == 0 ||
107 (td->td_flags & TDF_ASTPENDING) == 0))
108 printf("failed to set signal flags properly for ast()\n");
109 thread_unlock(td);
110 PROC_UNLOCK(p);
111 #endif
112 #endif
113 #ifdef KTRACE
114 KTRUSERRET(td);
115 #endif
116 /*
117 * If this thread tickled GEOM, we need to wait for the giggling to
118 * stop before we return to userland
119 */
120 if (td->td_pflags & TDP_GEOM)
121 g_waitidle();
122
123 /*
124 * Charge system time if profiling.
125 */
126 if (p->p_flag & P_PROFIL)
127 addupc_task(td, TRAPF_PC(frame), td->td_pticks * psratio);
128 /*
129 * Let the scheduler adjust our priority etc.
130 */
131 sched_userret(td);
132 KASSERT(td->td_locks == 0,
133 ("userret: Returning with %d locks held.", td->td_locks));
134 #ifdef VIMAGE
135 /* Unfortunately td_vnet_lpush needs VNET_DEBUG. */
136 VNET_ASSERT(curvnet == NULL,
137 ("%s: Returning on td %p (pid %d, %s) with vnet %p set in %s",
138 __func__, td, p->p_pid, td->td_name, curvnet,
139 (td->td_vnet_lpush != NULL) ? td->td_vnet_lpush : "N/A"));
140 #endif
141 #ifdef XEN
142 PT_UPDATES_FLUSH();
143 #endif
144 }
145
146 /*
147 * Process an asynchronous software trap.
148 * This is relatively easy.
149 * This function will return with preemption disabled.
150 */
151 void
152 ast(struct trapframe *framep)
153 {
154 struct thread *td;
155 struct proc *p;
156 int flags;
157 int sig;
158
159 td = curthread;
160 p = td->td_proc;
161
162 CTR3(KTR_SYSC, "ast: thread %p (pid %d, %s)", td, p->p_pid,
163 p->p_comm);
164 KASSERT(TRAPF_USERMODE(framep), ("ast in kernel mode"));
165 WITNESS_WARN(WARN_PANIC, NULL, "Returning to user mode");
166 mtx_assert(&Giant, MA_NOTOWNED);
167 THREAD_LOCK_ASSERT(td, MA_NOTOWNED);
168 td->td_frame = framep;
169 td->td_pticks = 0;
170
171 /*
172 * This updates the td_flag's for the checks below in one
173 * "atomic" operation with turning off the astpending flag.
174 * If another AST is triggered while we are handling the
175 * AST's saved in flags, the astpending flag will be set and
176 * ast() will be called again.
177 */
178 thread_lock(td);
179 flags = td->td_flags;
180 td->td_flags &= ~(TDF_ASTPENDING | TDF_NEEDSIGCHK | TDF_NEEDSUSPCHK |
181 TDF_NEEDRESCHED | TDF_ALRMPEND | TDF_PROFPEND | TDF_MACPEND);
182 thread_unlock(td);
183 PCPU_INC(cnt.v_trap);
184
185 if (td->td_ucred != p->p_ucred)
186 cred_update_thread(td);
187 if (td->td_pflags & TDP_OWEUPC && p->p_flag & P_PROFIL) {
188 addupc_task(td, td->td_profil_addr, td->td_profil_ticks);
189 td->td_profil_ticks = 0;
190 td->td_pflags &= ~TDP_OWEUPC;
191 }
192 if (flags & TDF_ALRMPEND) {
193 PROC_LOCK(p);
194 psignal(p, SIGVTALRM);
195 PROC_UNLOCK(p);
196 }
197 if (flags & TDF_PROFPEND) {
198 PROC_LOCK(p);
199 psignal(p, SIGPROF);
200 PROC_UNLOCK(p);
201 }
202 #ifdef MAC
203 if (flags & TDF_MACPEND)
204 mac_thread_userret(td);
205 #endif
206 if (flags & TDF_NEEDRESCHED) {
207 #ifdef KTRACE
208 if (KTRPOINT(td, KTR_CSW))
209 ktrcsw(1, 1);
210 #endif
211 thread_lock(td);
212 sched_prio(td, td->td_user_pri);
213 mi_switch(SW_INVOL | SWT_NEEDRESCHED, NULL);
214 thread_unlock(td);
215 #ifdef KTRACE
216 if (KTRPOINT(td, KTR_CSW))
217 ktrcsw(0, 1);
218 #endif
219 }
220
221 /*
222 * Check for signals. Unlocked reads of p_pendingcnt or
223 * p_siglist might cause process-directed signal to be handled
224 * later.
225 */
226 if (flags & TDF_NEEDSIGCHK || p->p_pendingcnt > 0 ||
227 !SIGISEMPTY(p->p_siglist)) {
228 PROC_LOCK(p);
229 mtx_lock(&p->p_sigacts->ps_mtx);
230 while ((sig = cursig(td, SIG_STOP_ALLOWED)) != 0)
231 postsig(sig);
232 mtx_unlock(&p->p_sigacts->ps_mtx);
233 PROC_UNLOCK(p);
234 }
235 /*
236 * We need to check to see if we have to exit or wait due to a
237 * single threading requirement or some other STOP condition.
238 */
239 if (flags & TDF_NEEDSUSPCHK) {
240 PROC_LOCK(p);
241 thread_suspend_check(0);
242 PROC_UNLOCK(p);
243 }
244
245 if (td->td_pflags & TDP_OLDMASK) {
246 td->td_pflags &= ~TDP_OLDMASK;
247 kern_sigprocmask(td, SIG_SETMASK, &td->td_oldsigmask, NULL, 0);
248 }
249
250 userret(td, framep);
251 mtx_assert(&Giant, MA_NOTOWNED);
252 }
253
254 const char *
255 syscallname(struct proc *p, u_int code)
256 {
257 static const char unknown[] = "unknown";
258 struct sysentvec *sv;
259
260 sv = p->p_sysent;
261 if (sv->sv_syscallnames == NULL || code >= sv->sv_size)
262 return (unknown);
263 return (sv->sv_syscallnames[code]);
264 }
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