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/8.4/sys/kern/subr_trap.c 249524 2013-04-15 19:45:09Z smh $");
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/syscallsubr.h>
66 #include <sys/sysent.h>
67 #include <sys/systm.h>
68 #include <sys/vmmeter.h>
69 #ifdef KTRACE
70 #include <sys/uio.h>
71 #include <sys/ktrace.h>
72 #endif
73 #include <security/audit/audit.h>
74
75 #include <machine/cpu.h>
76
77 #ifdef VIMAGE
78 #include <net/vnet.h>
79 #endif
80
81 #ifdef XEN
82 #include <vm/vm.h>
83 #include <vm/vm_param.h>
84 #include <vm/pmap.h>
85 #endif
86
87 #include <security/mac/mac_framework.h>
88
89 /*
90 * Define the code needed before returning to user mode, for trap and
91 * syscall.
92 */
93 void
94 userret(struct thread *td, struct trapframe *frame)
95 {
96 struct proc *p = td->td_proc;
97
98 CTR3(KTR_SYSC, "userret: thread %p (pid %d, %s)", td, p->p_pid,
99 td->td_name);
100 KASSERT((p->p_flag & P_WEXIT) == 0,
101 ("Exiting process returns to usermode"));
102 #if 0
103 #ifdef DIAGNOSTIC
104 /* Check that we called signotify() enough. */
105 PROC_LOCK(p);
106 thread_lock(td);
107 if (SIGPENDING(td) && ((td->td_flags & TDF_NEEDSIGCHK) == 0 ||
108 (td->td_flags & TDF_ASTPENDING) == 0))
109 printf("failed to set signal flags properly for ast()\n");
110 thread_unlock(td);
111 PROC_UNLOCK(p);
112 #endif
113 #endif
114 #ifdef KTRACE
115 KTRUSERRET(td);
116 #endif
117 /*
118 * If this thread tickled GEOM, we need to wait for the giggling to
119 * stop before we return to userland
120 */
121 if (td->td_pflags & TDP_GEOM)
122 g_waitidle();
123
124 /*
125 * Charge system time if profiling.
126 */
127 if (p->p_flag & P_PROFIL)
128 addupc_task(td, TRAPF_PC(frame), td->td_pticks * psratio);
129 /*
130 * Let the scheduler adjust our priority etc.
131 */
132 sched_userret(td);
133 KASSERT(td->td_locks == 0,
134 ("userret: Returning with %d locks held.", td->td_locks));
135 KASSERT(td->td_vp_reserv == 0,
136 ("userret: Returning while holding vnode reservation"));
137 #ifdef VIMAGE
138 /* Unfortunately td_vnet_lpush needs VNET_DEBUG. */
139 VNET_ASSERT(curvnet == NULL,
140 ("%s: Returning on td %p (pid %d, %s) with vnet %p set in %s",
141 __func__, td, p->p_pid, td->td_name, curvnet,
142 (td->td_vnet_lpush != NULL) ? td->td_vnet_lpush : "N/A"));
143 #endif
144 #ifdef XEN
145 PT_UPDATES_FLUSH();
146 #endif
147 }
148
149 /*
150 * Process an asynchronous software trap.
151 * This is relatively easy.
152 * This function will return with preemption disabled.
153 */
154 void
155 ast(struct trapframe *framep)
156 {
157 struct thread *td;
158 struct proc *p;
159 int flags;
160 int sig;
161
162 td = curthread;
163 p = td->td_proc;
164
165 CTR3(KTR_SYSC, "ast: thread %p (pid %d, %s)", td, p->p_pid,
166 p->p_comm);
167 KASSERT(TRAPF_USERMODE(framep), ("ast in kernel mode"));
168 WITNESS_WARN(WARN_PANIC, NULL, "Returning to user mode");
169 mtx_assert(&Giant, MA_NOTOWNED);
170 THREAD_LOCK_ASSERT(td, MA_NOTOWNED);
171 td->td_frame = framep;
172 td->td_pticks = 0;
173
174 /*
175 * This updates the td_flag's for the checks below in one
176 * "atomic" operation with turning off the astpending flag.
177 * If another AST is triggered while we are handling the
178 * AST's saved in flags, the astpending flag will be set and
179 * ast() will be called again.
180 */
181 thread_lock(td);
182 flags = td->td_flags;
183 td->td_flags &= ~(TDF_ASTPENDING | TDF_NEEDSIGCHK | TDF_NEEDSUSPCHK |
184 TDF_NEEDRESCHED | TDF_ALRMPEND | TDF_PROFPEND | TDF_MACPEND);
185 thread_unlock(td);
186 PCPU_INC(cnt.v_trap);
187
188 if (td->td_ucred != p->p_ucred)
189 cred_update_thread(td);
190 if (td->td_pflags & TDP_OWEUPC && p->p_flag & P_PROFIL) {
191 addupc_task(td, td->td_profil_addr, td->td_profil_ticks);
192 td->td_profil_ticks = 0;
193 td->td_pflags &= ~TDP_OWEUPC;
194 }
195 if (flags & TDF_ALRMPEND) {
196 PROC_LOCK(p);
197 psignal(p, SIGVTALRM);
198 PROC_UNLOCK(p);
199 }
200 if (flags & TDF_PROFPEND) {
201 PROC_LOCK(p);
202 psignal(p, SIGPROF);
203 PROC_UNLOCK(p);
204 }
205 #ifdef MAC
206 if (flags & TDF_MACPEND)
207 mac_thread_userret(td);
208 #endif
209 if (flags & TDF_NEEDRESCHED) {
210 #ifdef KTRACE
211 if (KTRPOINT(td, KTR_CSW))
212 ktrcsw(1, 1, __func__);
213 #endif
214 thread_lock(td);
215 sched_prio(td, td->td_user_pri);
216 mi_switch(SW_INVOL | SWT_NEEDRESCHED, NULL);
217 thread_unlock(td);
218 #ifdef KTRACE
219 if (KTRPOINT(td, KTR_CSW))
220 ktrcsw(0, 1, __func__);
221 #endif
222 }
223
224 /*
225 * Check for signals. Unlocked reads of p_pendingcnt or
226 * p_siglist might cause process-directed signal to be handled
227 * later.
228 */
229 if (flags & TDF_NEEDSIGCHK || p->p_pendingcnt > 0 ||
230 !SIGISEMPTY(p->p_siglist)) {
231 PROC_LOCK(p);
232 mtx_lock(&p->p_sigacts->ps_mtx);
233 while ((sig = cursig(td, SIG_STOP_ALLOWED)) != 0)
234 postsig(sig);
235 mtx_unlock(&p->p_sigacts->ps_mtx);
236 PROC_UNLOCK(p);
237 }
238 /*
239 * We need to check to see if we have to exit or wait due to a
240 * single threading requirement or some other STOP condition.
241 */
242 if (flags & TDF_NEEDSUSPCHK) {
243 PROC_LOCK(p);
244 thread_suspend_check(0);
245 PROC_UNLOCK(p);
246 }
247
248 if (td->td_pflags & TDP_OLDMASK) {
249 td->td_pflags &= ~TDP_OLDMASK;
250 kern_sigprocmask(td, SIG_SETMASK, &td->td_oldsigmask, NULL, 0);
251 }
252
253 userret(td, framep);
254 mtx_assert(&Giant, MA_NOTOWNED);
255 }
256
257 const char *
258 syscallname(struct proc *p, u_int code)
259 {
260 static const char unknown[] = "unknown";
261 struct sysentvec *sv;
262
263 sv = p->p_sysent;
264 if (sv->sv_syscallnames == NULL || code >= sv->sv_size)
265 return (unknown);
266 return (sv->sv_syscallnames[code]);
267 }
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